HYDROCONVERSION IN AN EBULLATED OR HYBRID EBULLATED/ENTRAINED BED OF A FEEDSTOCK COMPRISING A PLASTIC FRACTION
The present invention relates to a process for the hydroconversion of a feedstock including a plastic fraction (102), notably derived from plastic waste, and a heavy hydrocarbon fraction (101), notably a heavy hydrocarbon fraction containing a portion of at least 50% by weight, preferably at least 80% by weight, having a boiling temperature of at least 300° C. Hydroconversion involves one or more ebullated bed or hybrid ebullated-entrained bed reactors (20), and preferably two successive hydroconversion steps, in order to produce higher-quality, lower-boiling materials, for example for fuel production purposes, while at the same time allowing waste plastics to be upgraded.
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The present invention relates to the field of hydroconversion of feedstocks including a plastic fraction, notably from plastic waste, and a heavy hydrocarbon fraction, notably a heavy hydrocarbon fraction containing a portion of at least 50% by weight, preferably at least 80% by weight, having a boiling temperature of at least 300° C.
The heavy hydrocarbon fraction may be a crude oil or may result from the distillation and/or refining of a crude oil, typically a topped crude oil, a residue from the atmospheric and/or vacuum distillation of a crude oil. This heavy hydrocarbon fraction is associated with a fraction of plastic(s).
In particular, the present invention relates to a process for the hydroconversion of such a mixed feedstock, including at least one hydroconversion step using one or more reactors operating in an ebullated bed or a hybrid ebullated-entrained bed, and preferably two successive hydroconversion steps, with a view to producing higher-quality, lower-boiling materials, for example for fuel production purposes, while at the same time enabling the upgrading of plastic waste.
PRIOR ARTOver the past few years, the fuel and chemical industries have seen the emergence of processes incorporating products other than conventional petroleum products, for example products of renewable origin such as lignocellulosic biomass, or else products such as plastic waste, as a complement or in replacement for products of fossil origin.
For example, U.S. Pat. No. 8,623,102 is known, which relates to a process for liquefying biomass chosen from algae, lignocellulosic biomass or one or more lignocellulosic biomass constituents chosen from the group formed by cellulose, hemicellulose and/or lignin to produce fuel bases, said process including two successive hydroconversion steps under high hydrogen pressure in ebullated bed reactors using a supported catalyst of the petroleum residue hydroconversion type and a suspension composed of the biomass and a solvent.
In particular, in a context of circular economy and of waste reduction, special attention is paid to plastics, which are conventionally petroleum-derived products, in order to upgrade them.
The upgrading of plastic waste can consist in transforming said plastics, by mechanical and/or chemical means, in order to make possible again the production of plastics or of plastic-based objects. This is then the recycling of plastic waste.
This upgrading of plastic waste can also follow the path of energy upgrading, in particular as regards plastic waste which is non-recyclable or difficult to recycle, as an alternative, in certain cases, to landfilling.
Typically, the energy upgrading of plastic waste consists in producing energy, in the form of electricity and/or of heat. For example, it is known to subject the plastics resulting from the collection and sorting channels to a pyrolysis step in order to produce, inter alia, plastic pyrolysis oils, which are typically incinerated to generate electricity and/or used as fuel in industrial boilers or for urban heating.
In the field of hydroconversion, i.e. the conversion of hydrocarbon feedstocks under high hydrogen pressure into products with lower boiling point ranges than those of the original feedstock, patent application WO 2020/129020 describes a process for the hydroconversion of a polymer mixture based on the use of an entrained catalyst, also known as the “slurry” hydroconversion process. The very small catalyst is dispersed in the reaction medium, uniformly distributed in the reactor, and entrained with the products leaving the reactor. According to said process, a mixture of plastics is processed using slurry technology, based on the use of a reactor operating with an entrained catalyst, and is converted into hydrocarbons with a boiling point ranging from 65° C. to 175° C., corresponding to a naphtha cut. Ultimately, this is a process for the chemical recycling of plastic waste, allowing used plastics to be converted into a naphtha cut, which is one of the main reagents for plastics production. The feedstock in the slurry hydroconversion process according to patent application WO 2020/129020 is a solid polymer mixture, which may be mixed with a residue under vacuum, and which is introduced as a slurry (solid suspension) into a reactor operating as an entrained bed. Although slurry processes are known to handle heavy feedstocks and to achieve higher degrees of conversion than other processes, for example hydroconversion processes using ebullated bed reactors employing a supported catalyst maintained in the reactor, a major drawback of slurry processes lies in the complex and costly management of the catalyst entrained with the conversion products, notably its separation from the end products.
OBJECTS AND SUMMARY OF THE INVENTIONThe present invention falls within the field of upgrading heavy feedstocks which are difficult to upgrade, such as petroleum residues, which generally contain high levels of impurities such as metals, sulfur, nitrogen, Conradson carbon and asphaltenes, in order to convert them into lighter products that can be upgraded as fuels, for example to produce gasolines or diesel fuels, or as raw materials for the petrochemical industry.
The inventors have demonstrated, surprisingly, that it is possible to incorporate a fraction of plastics derived from waste, in a variety of ways, into a heavy hydrocarbon feedstock conventionally treated in an ebullated bed or hybrid ebullated-entrained bed hydroconversion process, without significantly deteriorating the overall conversion of the feedstock.
The present invention thus proposes a process for the hydroconversion of a heavy hydrocarbon feedstock in an ebullated or hybrid ebullated-entrained bed, said feedstock including a fraction of plastics derived from waste, thus allowing the production of fuel bases and other upgradable hydrocarbons (light hydrocarbons, distillates destined for a steam cracker notably for the production of recycled polyolefins, bases for the production of bitumens, lubricants, etc.) while ensuring the upgrading of plastic waste which might otherwise be intended for landfill or incineration. More generally, the invention contributes toward increasing the proportion of plastic waste sent for recycling, while at the same time treating plastic impurities.
Thus, to achieve at least one of the abovementioned objectives, among others, the present invention proposes, according to a first aspect, a process for the hydroconversion of a feedstock, comprising the following successive steps:
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- (a) conditioning and introducing said feedstock into a first hydroconversion section including at least a first ebullated-bed or hybrid ebullated-entrained hydroconversion reactor comprising a first porous supported hydroconversion catalyst, said feedstock including between 1% and 50% by weight of a plastic fraction and 50% and 99% by weight of a heavy hydrocarbon fraction containing a portion of at least 50% by weight having a boiling point of at least 300° C., and containing sulfur, and nitrogen;
- (b) a first step of hydroconversion of said feedstock in the presence of hydrogen in said first hydroconversion section to obtain a first hydroconverted effluent;
- (c) optionally, a step of separating part or all of said first effluent resulting from step (b), to form at least one heavy cut boiling predominantly at a temperature greater than or equal to 350° C.; (d) optionally, a second hydroconversion step in a second hydroconversion section including at least a second ebullated bed or hybrid ebullated-entrained bed hydroconversion reactor of part or all of said first effluent resulting from step (b) or optionally of said heavy cut resulting from step (c), said second hydroconversion reactor comprising a second porous supported catalyst and operating in the presence of hydrogen, to produce a second hydroconverted effluent;
- step (b) and optional step (d) being performed at an absolute pressure of between 2 MPa and 38 MPa, at a temperature of between 300° C. and 550° C., at an hourly space velocity relative to the volume of each hydroconversion reactor of between 0.05 h−1 and 10 h−1, and with an amount of hydrogen of between 50 Nm3/m3 and 5000 Nm3/m3,
- (e) a step of fractionating all or some of said first hydroconverted effluent from step (b) or said second hydroconverted effluent from step (d), in a fractionation section, to produce at least one heavy liquid product boiling predominantly at a temperature greater than or equal to 350° C., said heavy liquid product containing a residual fraction boiling at a temperature greater than or equal to 540° C.
According to one or more implementations of the invention, in step (a), the plastic fraction and the heavy hydrocarbon fraction of the feedstock are introduced mixed into said at least one first hydroconversion reactor of the first hydroconversion section.
According to one or more implementations of the invention, in step (a), the plastic fraction in the form of solid particles is mixed with the heavy hydrocarbon fraction in such a way as to form a suspension, said suspension being heated to a temperature above the melting point of said plastic fraction to form the feedstock introduced into the first hydroconversion reactor.
According to one or more implementations of the invention, in step (a), the plastic fraction in the form of solid particles is premixed with a plastic diluent to form a first suspension, and said first suspension is then mixed with the heavy hydrocarbon fraction to form a second suspension, said second suspension being heated to a temperature above the melting temperature of said plastic fraction to form the feedstock introduced into the first hydroconversion reactor.
According to one or more embodiments of the invention, in step (a), the plastic fraction in the form of solid particles, preferably premixed with a plastic diluent to form a suspension, is heated to a temperature above the melting point of said plastic fraction to form a molten plastic fraction, and said molten plastic fraction is then mixed with the heavy hydrocarbon fraction in such a manner as to form the feedstock introduced into the first hydroconversion reactor.
According to one or more implementations of the invention, in step (a), the plastic fraction in solid particle form is heated to a temperature above the melting point of said plastic fraction to form a molten plastic fraction, and said molten plastic fraction is then mixed with a plastic diluent to form a dilute molten plastic fraction mixed with the heavy hydrocarbon fraction to form the feedstock introduced into the first hydroconversion reactor.
According to one or more implementations of the invention, in step (a), the plastic fraction and the heavy hydrocarbon fraction of the feedstock are introduced separately into said at least one first hydroconversion reactor of the first hydroconversion section.
According to one or more implementations of the invention, in step (a), the plastic fraction in the form of solid particles is fed into an extruder, preferably with a plastic diluent, in which it is progressively heated to a temperature above the melting point of said plastic fraction, and pressurized in said first hydroconversion reactor during conveying preferably for less than 15 minutes, and said extruded plastic fraction is introduced into the first hydroconversion reactor.
According to one or more implementations of the invention, in step (a), the plastic fraction in the form of solid particles is mixed with a plastic diluent in a mixing section and heated in a heating section to a temperature above the melting point of said plastic fraction, preferably between 60° C. and 295° C., prior to its introduction into the first hydroconversion reactor, the heating step possibly being performed before or after mixing with the plastic diluent, and preferably after mixing with the plastic diluent.
According to one or more implementations of the invention, in step (a), the plastic fraction in the form of solid particles is previously sent to a mixer to be mixed with a plastic diluent and form a suspension, preferably at a temperature greater than or equal to room temperature and less than the melting temperature of said plastic fraction, and said plastic fraction in the form of a suspension is introduced into the first hydroconversion reactor.
According to one or more implementations of the invention, in step (a), the plastic fraction in the form of solid particles is premixed with a plastic diluent and with the first porous supported hydroconversion catalyst in a distribution and mixing box to form a suspension, and said suspension is then introduced into the first hydroconversion reactor via the means for injecting the catalyst into the first hydroconversion reactor.
According to one or more implementations of the invention, the feedstock includes between 5% and 30% by weight, preferably between 5% and 20% by weight, of said plastic feedstock, and between 70% and 95% by weight, preferably between 80% and 95% by weight, of said heavy hydrocarbon feedstock.
According to one or more implementations of the invention, the process includes separation step (c) which separates part, or all, of the first hydroconverted effluent from step (b) to produce at least the heavy cut boiling predominantly at a temperature greater than or equal to 350° C., and includes the second step (d) of hydroconverting said heavy cut.
According to one or more implementations of the invention, the hydroconversion reactor(s) of the first hydroconversion section in step (b), and optionally in hydroconversion step (d), are hybrid ebullated-entrained bed reactors, said process also including a step of introducing a catalyst precursor, preferably molybdenum 2-ethylhexanoate, prior to injection of said feedstock into said at least one first ebullated-entrained hybrid bed reactor of the first hydroconversion section, in such a way that a colloidal or molecular catalyst, preferably including molybdenum disulfide, is formed when said feedstock reacts with sulfur.
According to one or more implementations of the invention, the first hydroconversion catalyst, and optionally the second hydroconversion catalyst, contains at least one non-noble Group VIII metal chosen from nickel and cobalt, preferably nickel, and at least one Group VIB metal chosen from molybdenum and tungsten, preferably molybdenum, and including an amorphous support, preferably alumina.
According to one or more implementations of the invention, the heavy hydrocarbon fraction of the feedstock comprises, and may consist of, at least one of the following feedstocks, alone or as a mixture: a crude oil, a topped crude oil, an atmospheric residue or vacuum residue from the atmospheric or vacuum distillation of a crude oil (preferably from the primary fractionation of crude oil), an atmospheric residue or vacuum residue from the atmospheric or vacuum distillation obtained via a direct coal liquefaction process, and preferably is a vacuum residue from the vacuum distillation of a crude oil (preferably from the primary fractionation of crude oil).
According to one or more implementations of the invention, the heavy hydrocarbon fraction of the feedstock comprises sulfur in a content of greater than 0.5% by weight and nitrogen in a content of between 1 ppm and 8000 ppm by weight, and preferably a Conradson carbon content of at least 3% by weight, and/or a C7 asphaltenes content of at least 1% by weight, and/or a metal content of at least 20 ppm by weight.
According to one or more implementations of the invention, the plastic fraction of the feedstock comprises one or more polymers chosen from the list consisting of alkene polymers, diene polymers, vinyl polymers and styrene polymers.
According to one or more implementations of the invention, the plastic fraction of the feedstock comprises at least 50% by weight, preferably at least 80% by weight, preferably at least 90% by weight, and very preferably at least 94% by weight, of polyolefins relative to the total weight of the plastic fraction of the feedstock.
According to one or more implementations of the invention, the polyolefins of the plastic fraction of the feedstock are chosen from the list consisting of polyethylene (PE), polypropylene (PP) and/or copolymers of ethylene and propylene.
According to one or more embodiments of the invention, the plastic diluent is a hydrocarbon or a mixture of liquid hydrocarbons, and preferably the plastic diluent is a hydrocarbon oil consisting of hydrocarbons of which at least 50% by weight, relative to the total weight of the hydrocarbon oil, have a boiling temperature of between 180° C. and 540° C., preferably chosen from the list consisting of a vacuum gas oil (VGO), a settling oil or a cycle oil such as an FCC fluidized bed catalytic cracking effluent such as a heavy cycle oil (HCO) or a light cycle oil (LCO), a pyrolysis oil from a hydrocracker, a light gas oil, an atmospheric residue, a vacuum residue, a deasphalted oil, and a resin, and more preferentially the plastic diluent is an LCO, an HCO or a VGO.
According to one or more embodiments of the invention, the plastic diluent is a hydrocarbon or a mixture of liquid hydrocarbons comprising, e.g. being constituted by, xylene, toluene, a gasoline, or mixtures thereof.
Other subjects and advantages of the invention will become apparent on reading the description which follows of particular exemplary embodiments of the invention, which are given as nonlimiting examples, the description being made with reference to the appended figures described below.
In the figures, the same references denote identical or analogous elements.
DESCRIPTION OF THE EMBODIMENTSEmbodiments of the process according to the invention will now be described in detail. In the following detailed description, many specific details are disclosed in order to provide a deeper understanding of the process. However, it will be apparent to a person skilled in the art that the process can be performed without these specific details. In other cases, well-known characteristics have not been described in detail in order to avoid unnecessarily complicating the description.
A few definitions are given below for better understanding of the invention.
In the present description, the term “to comprise” is synonymous with (means the same thing as) “to include” and “to contain”, and is inclusive or open-ended and does not exclude other elements that are not mentioned. It is understood that the term “to comprise” includes the exclusive and closed term “to consist of”.
In the present description, the expression “between . . . and . . . ” means that the limiting values of the interval are included in the described range of values, unless otherwise specified.
In the present invention, the different ranges of values of given parameters can be used alone or in combination. For example, a preferred range of pressure values can be combined with a more preferred range of temperature values, or a preferred range of values of a chemical compound or element can be combined with a more preferred range of values of another chemical compound or element.
In the present description, a mixture of substances in the form of a suspension, also called a slurry, corresponds, usually, to a system formed of solid particles dispersed in a liquid (liquid dispersion). More specifically, a plastic fraction of the feedstock in the form of a suspension corresponds to a system including solid plastic particles dispersed in a liquid, for example a system including between 1% by weight and 50% by weight of solid plastic particles dispersed in a liquid, or even between 1% by weight and 30% by weight or else between 5% by weight and 20% by weight. The liquid continuous phase in which the solid plastic particles are dispersed may be a diluent and/or the liquid heavy fraction of the feedstock. According to the definition given, it does not comprise the polymer(s) of the plastic fraction, which would be melted.
The term “hydroconversion” refers to a process, the main aim of which is to reduce the boiling point range of a feedstock including at least 50% of a heavy hydrocarbon fraction, and in which a substantial part of the feedstock is converted into products having lower boiling point ranges than those of the starting feedstock. Hydroconversion generally involves the fragmentation of larger hydrocarbon molecules to give smaller molecular fragments having a smaller number of carbon atoms and a higher hydrogen-to-carbon ratio. The reactions performed during hydroconversion make it possible to reduce the size of molecules of hydrocarbons, mainly by cleaving carbon-carbon bonds, in the presence of hydrogen in order to saturate the severed bonds and the aromatic rings. The mechanism by which the hydroconversion takes place typically involves the formation of hydrocarbon free radicals during the fragmentation, mainly by thermal cracking, followed by the capping of the endings or fragments of free radicals with hydrogen in the presence of active catalyst sites. Needless to say, during a hydroconversion process, other reactions typically associated with hydrotreating may take place, such as, inter alia, the removal of sulfur or nitrogen from the feedstock, or the saturation of olefins, and as defined more broadly below.
The term “hydrotreating”, commonly known as “HDT”, refers to a milder operation, the main aim of which is to remove impurities, such as sulfur, nitrogen, oxygen, halides and traces of metals, from the feedstock and to saturate olefins and/or to stabilize free radicals of hydrocarbons by reacting them with hydrogen rather than by leaving them to react with themselves. The main aim is not to change the boiling point range of the feedstock. Thus, the hydrotreating notably comprises hydrodesulfurization (commonly known as “HDS”) reactions, hydrodenitrogenation (commonly known as “HDN”) reactions and hydrodemetallization (commonly known as “HDM”) reactions, accompanied by hydrogenation, hydrodeoxygenation, hydrodearomatization, hydroisomerization, hydrodealkylation, hydrocracking or hydrodeasphalting reactions and by the reduction of Conradson carbon. Hydrotreating is most often performed using a fixed bed reactor, although other reactors can also be used for hydrotreating, for example an ebullated bed hydrotreating reactor.
The term “hydroconversion reactor” refers to any vessel in which the hydroconversion of a feedstock is the main aim, e.g. the cracking of the feedstock (that is to say, the reduction of the boiling point range), in the presence of hydrogen and of a hydroconversion catalyst. Hydroconversion reactors typically comprise at least one inlet orifice through which the feedstock and hydrogen can be introduced and at least one outlet orifice from which an upgraded material can be withdrawn. Specifically, hydroconversion reactors are also characterized in that they have sufficient thermal energy to bring about the fragmentation of larger hydrocarbon molecules to give smaller molecules by thermal decomposition. Examples of hydroconversion reactors comprise, without being limited thereto, entrained bed reactors, also called slurry reactors (reactors having three phases—liquid, gas, solid—in which the solid and liquid phases can behave as a homogeneous phase), ebullated bed reactors (fluidized reactors having three phases), moving bed reactors (reactors having three phases with downward movement of the solid catalyst and upward or downward flow of liquid and of gas) and fixed bed reactors (reactors having three phases with downward runoff of liquid feedstock onto a fixed bed of supported catalyst with hydrogen flowing typically simultaneously with the liquid, but possibly countercurrentwise in some cases).
The terms “hybrid bed” and “hybrid ebullated bed” and “hybrid ebullated-entrained bed” for a hydroconversion reactor refer to an ebullated-bed hydroconversion reactor comprising an entrained catalyst in addition to the porous supported catalyst maintained in the ebullated-bed reactor. In a similar manner, for a hydroconversion process, these terms thus refer to a process comprising hybrid operation of an ebullated bed and an entrained bed in at least one and the same hydroconversion reactor. The hybrid bed is a mixed bed of two types of catalyst of necessarily different particle size and/or density, one type of catalyst—the “porous supported catalyst”—being maintained in the reactor and the other type of catalyst—the “entrained catalyst”, also commonly referred to as the “slurry catalyst”—being entrained out of the reactor with the effluent (upgraded feedstock). In the present invention, the entrained catalyst is a colloidal catalyst or a molecular catalyst, as defined below.
The terms “colloidal catalyst” and “colloidally dispersed catalyst” refer to catalyst particles having a particle size that is colloidal, e.g. less than 1 μm in size (diameter), preferably less than 500 nm in size, more preferably less than 250 nm in size, or less than 100 nm in size, or less than 50 nm in size, or less than 25 nm in size, or less than 10 nm in size, or less than 5 nm in size. The term “colloidal catalyst” comprises, but is not limited to, molecular or molecularly dispersed catalyst compounds.
The terms “molecular catalyst” and “molecularly dispersed catalyst” refer to catalyst compounds which are essentially “dissolved” or completely dissociated from other catalyst compounds or molecules in a feedstock, nonvolatile liquid fraction, bottom fraction, residue, or other feedstock or product in which the catalyst may be found. They also refer to very small catalyst particles or sheets which contain only a few catalyst molecules joined together (e.g. 15 molecules or less).
The terms “porous supported catalyst”, “solid supported catalyst” and “supported catalyst” refer to catalysts which are typically used in conventional ebullated bed and fixed bed hydroconversion systems, including catalysts designed primarily for hydrocracking or hydrodemetallization and catalysts designed primarily for hydrotreating. Such catalysts typically comprise (i) a catalyst support having a large surface area and numerous interconnected channels or pores and (ii) fine particles of an active catalyst, such as cobalt, nickel, tungsten or molybdenum sulfides, or mixed sulfides of these elements (for example NiMo, CoMo, and the like), which are dispersed in the pores. Supported catalysts are commonly produced in the form of cylindrical extrudates (pellets) or of spherical solids, although other forms are possible.
The process according to the invention and its functioning are described in greater detail below, with reference to
In all the variants illustrated, certain steps of the hydroconversion process are similar. The sections of the hydroconversion facility implementing these similar steps are denoted by the same reference in the figures, for example the sections for hydroconversion 20, fractionation 30 and further treatment(s) 40 described below.
The object of the invention is to propose a process for hydroconverting a feedstock including between 1% and 50% by weight of a plastic fraction and between 50% and 99% by weight of a heavy hydrocarbon fraction containing a portion of at least 50% by weight having a boiling point of at least 300° C., and containing sulfur, metals, and nitrogen, or even metals, Conradson carbon and asphaltenes, comprising the following successive steps:
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- (a) conditioning and introducing the feedstock into a first hydroconversion section 20 including at least a first ebullated bed or hybrid bed reactor comprising a first porous supported hydroconversion catalyst;
- (b) a first step of hydroconverting said feedstock in the presence of hydrogen in said first hydroconversion section 20 to obtain a first hydroconverted effluent 105;
- (c) optionally, a step of separating part or all of said first effluent resulting from step (b), to recover at least one heavy cut boiling predominantly at a temperature greater than or equal to 350° C.;
- (d) optionally, a second hydroconversion step in a second hydroconversion section (not shown in the figures) including at least one second ebullated bed or hybrid bed reactor of some or all of said first effluent resulting from step (b) or optionally of said heavy cut from step (c), said second reactor comprising a second porous supported catalyst and operating in the presence of hydrogen, to produce a second hydroconverted effluent;
- step (b) and optional step (d) being performed at an absolute pressure of between 2 MPa and 38 MPa, at a temperature of between 300° C. and 550° C., at an hourly space velocity relative to the volume of each reactor of between 0.05 h−1 and 10 h−1, and with an amount of hydrogen of between 50 Nm3/m3 and 5000 Nm3/m3,
- (e) a step of fractionating all or some of said first hydroconverted effluent 105 from step (b) or said second hydroconverted effluent from step (d), in a fractionation section (30), to produce at least one heavy product boiling predominantly at a temperature greater than or equal to 350° C., said heavy product containing a residual fraction boiling at a temperature greater than or equal to 540° C.
According to a key aspect of the invention, the feedstock comprises a plastic fraction and a heavy hydrocarbon fraction.
The plastic fraction consists of between 1% and 50% by weight of the feedstock (total feedstock weight), preferably between 5% and 30% by weight of the feedstock, and more preferentially between 5% and 20% by weight of the feedstock.
The heavy hydrocarbon feedstock containing a portion of at least 50% by weight having a boiling point of at least 300° C., and containing sulfur, Conradson carbon, metals, nitrogen and asphaltenes, constitutes between 50% and 95% by weight of the feedstock, preferably between 70% and 95% by weight of the feedstock, and more preferentially between 80% and 95% by weight of the feedstock.
The sum of the plastic fraction and the heavy hydrocarbon fraction is equal to 100% by weight of the feedstock to be converted and sent to the first hydroconversion step. In other words, the feedstock to be converted consists of said plastic fraction and said heavy hydrocarbon fraction.
The plastic fraction of the feedstock of the process according to the invention comprises plastics which themselves more particularly comprise polymers. Thus, the term “plastic fraction” means a solid fraction of plastics including one or more polymers, and which may contain other compounds, such as additives of organic or inorganic origin and/or customary impurities, in particular resulting from the life cycle of plastic materials and articles, and/or resulting from the waste collection and sorting circuit. For example, the customary impurities may be metallic, organic or mineral; they may be packaging residues, food residues or compostable residues (biomass). Customary impurities may also comprise glass, wood, cardboard, paper, aluminum, iron, metals, tires, rubber, silicones, rigid polymers, thermosetting polymers, household, chemical or cosmetic products, waste oils or water.
In the present description, the term “impurities of the plastics” denotes all the compounds of the plastic fraction which are not polymers and which are not capable of being converted during the hydroconversion step(s) of the process. For example, some organic additives can be, at least in part, converted during the hydroconversion, in the same way as the polymers. These are thus not regarded as impurities of the plastics. On the other hand, some of the inorganic additives can be removed during the hydroconversion, for example those containing metals, and/or sulfur, and/or nitrogen, and/or oxygen, and/or other heteroatoms (Cl, Br, and the like). They are for their part regarded as impurities of the plastics.
The plastics included in the plastic fraction of the feedstock of the process according to the invention are generally production rejects and/or waste, notably household waste, building waste or electrical and electronic equipment waste. Preferably, the plastic waste is derived from collection and sorting channels. Plastics or plastic materials are generally polymers which are usually mixed with additives, for the purpose of constituting, after forming into shape, various materials and objects (injection-moulded parts, tubes, films, fibres, fabrics, mastics, coatings, etc.). The additives used in plastics may be organic compounds or inorganic compounds. They are, for example, fillers, colorants, pigments, plasticizers, property modifiers, combustion retardants, etc.
The plastic fraction of the feedstock of the process according to the invention thus comprises polymers and in particular thermoplastics. The polymers included in the plastic fraction of the feedstock can be alkene polymers, diene polymers, vinyl polymers, styrene polymers (for example: polystyrene “PS”), polyesters and/or polyamides. Preferentially, the polymers included in the plastic fraction of the feedstock are alkene polymers, diene polymers, vinyl polymers and/or styrene polymers (for example: polystyrene “PS”). Preferably, the polymers included in the plastic feedstock are polyolefins, such as polyethylene (PE), polypropylene (PP) and/or copolymers of ethylene and of propylene. For example, the plastic fraction of the feedstock comprises at least 50% by weight, preferably at least 80% by weight, in a preferred way at least 90% by weight and very preferably at least 94% by weight of polyolefins, relative to the total weight of the plastic fraction of the feedstock.
The plastic fraction of the feedstock may comprise mixtures of polymers, especially mixtures of thermoplastics and/or mixtures of thermoplastics and other polymers, and compounds other than these thermoplastics and polymers, in particular the additives advantageously used to formulate the plastic material and generally customary impurities originating from the life cycle of the plastic materials and objects, and/or originating from the waste collection and sorting channels. The plastic fraction of the feedstock of the process according to the invention generally comprises less than 50% by weight of these additives and customary impurities, preferably less than 20% by weight and in a preferred manner less than 10% by weight.
Said plastic fraction of the feedstock may advantageously be pretreated upstream of the process so as to at least remove all or part of the “coarse” customary impurities, that is to say customary impurities in the form of particles with a size of greater than or equal to 10 mm, preferably of greater than or equal to 5 mm, or even of greater than or equal to 1 mm, for example customary impurities of the type of wood, paper, biomass, iron, aluminum, glass, and the like, and to put it into form, generally into the form of particles (divided solids), so as to facilitate the treatment in the process. This pretreatment may comprise a milling step, a step of washing at atmospheric pressure and/or a drying step. This pretreatment may be performed at a different site, for example in a waste collection and sorting centre, or at the same site where the treatment process according to the invention is performed. Preferably, this pretreatment makes it possible to reduce the content of customary impurities to less than 6% by weight. On conclusion of the pretreatment, the feedstock is generally stored in the form of particles, for example in the form of ground material or of powder, so as to facilitate the handling and transportation up to the process.
The heavy hydrocarbon fraction of the feedstock of the process according to the invention is a heavy hydrocarbon fraction containing a portion of at least 50% having a boiling temperature of at least 300° C., preferably at least 350° C., and even more preferably at least 375° C.
This heavy hydrocarbon fraction of the feedstock may be a crude oil, or originate from the refining of a crude oil or the processing of another hydrocarbon source in a refinery.
Preferably, the heavy hydrocarbon fraction of the feedstock is a crude oil, a topped crude oil or consists of atmospheric residues and/or vacuum residues from the atmospheric and/or vacuum distillation of a crude oil.
The heavy hydrocarbon fraction of the feedstock may also consist of atmospheric and/or vacuum residues from the atmospheric and/or vacuum distillation of effluents from thermal conversion, hydrotreating, hydrocracking and/or hydroconversion units.
Preferably, the heavy hydrocarbon fraction of the feedstock consists of vacuum residues. These vacuum residues generally contain a portion of at least 50% having a boiling temperature of at least 450° C., and more often of at least 500° C., or even at least 540° C. Vacuum residues may come directly from crude oil, or from other refining units, such as, inter alia, residue hydrotreating, residue hydrocracking, and residue visbreaking. Preferably, the vacuum residues are vacuum residues from the vacuum distillation column of the primary crude fractionation (referred to as the “straight run”, or abbreviated as “SR”).
The heavy hydrocarbon fraction of the feedstock may also consist of vacuum distillates, originating either directly from the crude oil, or from cuts from other refining units, such as, inter alia, cracking units, like FCC (Fluid Catalytic Cracking) and hydrocracking, and thermal conversion units, like cokers or visbreakers.
The heavy hydrocarbon fraction of the feedstock may also consist of aromatic cuts extracted from a lubricant production unit, deasphalted oils from a deasphalting unit, also known as DAO (deasphalting unit raffinates), asphalts from a deasphalting unit (deasphalting unit residues).
The heavy hydrocarbon fraction of the feedstock may also be a residual fraction derived from the direct liquefaction of coal (an atmospheric residue and/or a vacuum residue resulting, for example from the H-Coal™ process), a vacuum distillate derived from the direct liquefaction of coal (for instance the H-Coal™ process), or else a residual fraction derived from the direct liquefaction of lignocellulosic biomass, alone or as a mixture with coal and/or a petroleum fraction.
All these fractions may be used to constitute the heavy hydrocarbon fraction of the feedstock treated according to the invention, alone or as a mixture.
According to one or more implementations, the heavy hydrocarbon fraction comprises, and may consist of, at least one of the following feedstocks, alone or as mixtures: a crude oil, a topped crude oil, an atmospheric residue or a vacuum residue from the atmospheric or vacuum distillation of a crude oil (preferably from the primary fractionation of crude oil), an atmospheric residue or a vacuum residue from the atmospheric or vacuum distillation obtained via a direct coal liquefaction process, and preferably is a vacuum residue from the vacuum distillation of a crude oil (preferably from the primary fractionation of crude oil).
The heavy hydrocarbon fraction of the feedstock treated according to the invention contains impurities, such as sulfur and nitrogen. It may also contain impurities such as metals, Conradson carbon and asphaltenes, in particular C7 asphaltenes which are insoluble in heptane.
The metal contents may be greater than or equal to 20 ppm by weight, preferably greater than or equal to 100 ppm by weight.
The sulfur content may be greater than or equal to 0.1% by weight, or even greater than or equal to 0.5% or 1%, and may be greater than or equal to 2% by weight.
The nitrogen content is usually between 1 ppm and 8000 ppm by weight, more generally between 200 ppm and 8000 ppm by weight, for example between 2000 ppm and 8000 ppm by weight.
The content of C7 asphaltenes (compounds insoluble in heptane according to the standard ASTM D 6560, also corresponding to the standard NF T60-115) is at least 1% by weight and is often greater than or equal to 3% by weight. C7 asphaltenes are compounds known to inhibit the conversion of residual cuts, both by their ability to form heavy hydrocarbon residues, commonly known as coke, and by their tendency to produce sediments which severely limit the operability of hydrotreating and hydroconversion units.
The Conradson carbon content may be greater than or equal to 3% by weight, or even at least 5% by weight. The content of Conradson carbon is defined by the standard ASTM D 482 and represents, for a person skilled in the art, a well-known evaluation of the amount of carbon residue produced after a pyrolysis under standard temperature and pressure conditions.
These contents are expressed as weight percentages relative to the total weight of the heavy hydrocarbon fraction of the feedstock.
(a) Step of Conditioning and Injecting the Feedstock into the First Hydroconversion Reactor
The process according to the invention comprises a step (a) of conditioning and introducing the feedstock into a first hydroconversion section 20 including at least a first ebullated bed or hybrid bed reactor comprising a first porous supported hydroconversion catalyst.
The term “conditioning of the feedstock” means its conditioning for step (b) which follows of hydroconversion of the feedstock once it has been introduced into the first hydroconversion reactor, that is to say, putting it in a state and at temperature and pressure conditions suitable for the hydroconversion in the first hydroconversion reactor.
The plastic fraction of the feedstock may be introduced as a suspension into the first hydroconversion reactor, or in an essentially liquid form, previously mixed or not with the heavy hydrocarbon fraction of the feedstock.
The term “plastic fraction in a substantially liquid form” means that at least 80% by weight of the polymer(s) of the plastic fraction are in a liquid form, preferably at least 90% by weight, more preferably at least 95% by weight and even more preferably at least 98% by weight. The term “polymers of the plastic fraction in a liquid form” means polymers which are not in a solid form, the latter generally being regarded as corresponding to the crystalline, semicrystalline and amorphous states of a polymer.
The plastic fraction, in solid particle or essentially liquid form, is preferably mixed with a diluent prior to its introduction into the first hydroconversion reactor, and where appropriate prior to its mixture with the heavy hydrocarbon fraction of the feedstock. Said diluent, which is denoted by the term “plastic diluent” in the present description, referenced 107 in the figures, is formed by a hydrocarbon or a mixture of liquid hydrocarbons. For example, the plastic diluent is a hydrocarbon oil composed of hydrocarbons of which at least 50% by weight, relative to the total weight of the hydrocarbon oil, have a boiling temperature of between 180° C. and 540° C. Examples of suitable hydrocarbon diluents include, but are not limited to, vacuum gas oil known as “VGO” (which typically has a boiling range of 360° C. to 524° C.), settling oil or recycle oil (which typically has a boiling range of 360° C. to 550° C.), for example, FCC fluidized-bed catalytic cracking effluent, such as heavy cycle oil (HCO) or light cycle oil (LCO), or pyrolysis oil from a hydrocracker, light gas oil (which typically has a boiling range of 200° C. to 360° C.), atmospheric residues, vacuum residues (which typically have a boiling range of equal to or greater than 524° C.), deasphalted oils, and resins. The plastic diluent may also comprise, e.g. consist of, lighter liquid hydrocarbons (typically C5+ hydrocarbons, i.e. hydrocarbons which may contain 5 or more carbon atoms per molecule), for example xylene, toluene, gasoline, mixtures thereof, etc. According to one or more embodiments, the plastic diluent is an LCO, an HCO or a VGO. The plastic diluent 107 may serve as a solvent for the plastic fraction, in particular for the polymer(s) of the plastic fraction.
Different implementations of step (a) are possible, distinguished at a first level by the manner in which the feedstock is introduced into the first hydroconversion reactor:
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- according to a first embodiment of the invention, referred to as “direct injection” in the present description, the plastic fraction and the heavy hydrocarbon fraction are injected separately into the first hydroconversion reactor (i.e. without being mixed prior to their introduction into the hydroconversion reactor). This first embodiment notably makes it possible to limit the risk of incompatibility between the heavy hydrocarbon and plastic fractions of the feedstock, which could lead to demixing or precipitation of asphaltenes, for example. According to this first embodiment, different variants may be performed, which are better described below in relation to
FIGS. 1A, 1B, 1C and 1D . These variants are distinguished at a second level by the fact that the plastic fraction is introduced into the hydroconversion reactor in a predominantly liquid form (FIGS. 1A and 1B ) or in the form of a slurry (FIGS. 1C and 1D ). - according to a second embodiment of the invention, referred to as “indirect injection” in the present description, the plastic fraction and the heavy hydrocarbon fraction are mixed before being introduced into the hydroconversion reactor. The advantage of this second embodiment is notably better dispersion/dissolution of the plastic fraction in the feedstock, and such a more homogeneous feedstock introduced into the reactor is favorable, for example, for good fluidization of the catalyst, and for good hydrodynamic functioning of the reactor in general. It may also allow the use of common equipment, such as furnaces, feedstock distributors, mixers of hydrogen with the feedstock, for example of the T-mixer type, which may contribute toward reducing the investment costs. Once again, according to this second embodiment, different variants may be performed, described below in relation to
FIGS. 2A, 2B, 2C, 2D and 2E . These variants are distinguished at a second level by the fact that the plastic fraction is in solid or slurry form (FIGS. 2A and 2B ), or alternatively in essentially liquid form (FIGS. 2C, 2D and 2E ) when mixed with the heavy hydrocarbon fraction.
- according to a first embodiment of the invention, referred to as “direct injection” in the present description, the plastic fraction and the heavy hydrocarbon fraction are injected separately into the first hydroconversion reactor (i.e. without being mixed prior to their introduction into the hydroconversion reactor). This first embodiment notably makes it possible to limit the risk of incompatibility between the heavy hydrocarbon and plastic fractions of the feedstock, which could lead to demixing or precipitation of asphaltenes, for example. According to this first embodiment, different variants may be performed, which are better described below in relation to
In the figures, the bold arrows represent a stream in which the plastic fraction is in substantially liquid form (i.e. at least 90% by weight, preferably at least 95% by weight, and more preferentially at least 98% by weight of the plastic fraction is in liquid form), and the shaded rectangles represent devices in which the plastic fraction is heated so as to melt.
Direct Injection: Fractions Injected Separately into the Hydroconversion Reactor
Step (a1)Associated steps and devices other than step (a) in
The extrusion is conventionally a process which allows the injection or the forming of a polymer which is initially in the solid state. According to one extrusion process, the material is transported via one or more screws, kneaded and heated, which makes it possible to melt it. At the same time, the screw(s) convey the material and cause it to rise in pressure, which makes it possible to inject it into a die or into a mold.
According to this first variant of the first embodiment of the invention, the extrusion of the plastic fraction is a means of introducing the plastic fraction, which is solid at room temperature, into the hydroconversion reactor operating under high pressure and temperature. The extrusion thus makes it possible to heat, with a view to liquefying, and to pressurize the plastic fraction to the operating conditions of the first hydroconversion reactor as operated in step (b).
The material is not injected into a die or a mold as in a conventional extrusion process, thus not constituting a forming process, but it is injected directly into the first hydroconversion reactor of the first hydroconversion section 20.
According to this first variant of the first embodiment of the invention, the plastic fraction in the form of solid particles 102 is sent into an extruder 10, preferably with a plastic diluent 107 as described above, in which it is gradually heated to a temperature greater than the melting point of said plastic fraction, and placed at the pressure of said first hydroconversion reactor, during a conveying, preferably for a period of time of less than 15 minutes, and the plastic fraction thus extruded 103 is introduced into the first hydroconversion reactor of the first hydroconversion section 20.
During the extrusion, the plastic fraction is preferably gradually heated to a temperature greater than its melting point, so as to melt. Advantageously, at least 80% by weight of the plastic fraction is in the liquid form (molten), very advantageously at least 90% by weight, preferentially at least 95% by weight, or even 98% by weight, on conclusion of the extrusion. As described above, the plastic fraction generally contains compounds other than polymers, notably impurities of the plastics. Some of these non-polymeric compounds, including the impurities of the plastics, may be insoluble and/or have a higher melting point than the polymer(s) of the plastic fraction. Even if all of the polymer(s) melt, a portion of the liquid fraction, taking into account the non-polymeric compounds, may thus remain in a solid form. This is true for all the steps described below in which heating results in the total or virtually total liquefaction of the plastic fraction.
The extrusion temperature depends on the polymer composition of the plastic fraction (nature and proportion(s) of the polymer(s)). It may also depend on a plastic diluent 107 added to the plastic fraction during extrusion.
Preferably, the extruder 10 is operated at a temperature between a temperature 25° C. below the melting point of the plastic fraction and a temperature 25° C. above the melting point of the plastic fraction.
In the case where the plastic fraction comprises a mixture of polymers, the extruder 10 is operated at a temperature between 25° C. below the melting point of the least refractory polymer (i.e., which has the lowest melting point) of the plastic fraction and a temperature 25° C. above the melting point of the most refractory polymer (i.e., which has the highest melting point) of the plastic fraction.
Advantageously, the plastic fraction is preferably gradually heated in the extruder 10 to a temperature greater than the melting point of the polymer which has the highest melting point.
By way of indication, the melting point of polypropylene (PP) is approximately 170° C., the melting point of polyethylene (PE) is between approximately 85° C. and 140° C., and the melting point of polystyrene is between approximately 240° C. and 270° C.
The extrusion temperature is preferably such that it limits thermal degradation of the polymer(s), which may lead to the formation of undesirable solids. For example, the extrusion temperature is advantageously less than 200° C., notably in the case where the plastic fraction comprises mainly PE. It may advantageously be less than 300° C. in the case where the plastic fraction mainly comprises PS.
Preferably, the extruder 10 is operated at a temperature of between 60° C. and 295° C., more preferentially between 60° C. and 195° C.
Advantageously, the extruder 10 is operated at a temperature of between 60° C. and 165° C., so as to melt a plastic fraction mainly including PE as polymer.
Advantageously, the extruder 10 is operated at a temperature of between 145° C. and 195° C., so as to melt a plastic fraction mainly including PP as polymer.
Advantageously, the extruder 10 is operated at a temperature of between 215° C. and 295° C., so as to melt a plastic fraction mainly including PS as polymer.
The operating temperature of the extruder is advantageously adjusted according to the composition of the plastic fraction.
Advantageously, the extruder 10 comprises at least one screw conveying section, referred to as the extrusion section, fed with the plastic fraction.
The residence time in this extrusion section (volume of said section divided by the flow rate by volume of plastic fraction) is advantageously less than 15 minutes, preferably less than 10 minutes and in a preferred way less than 2 minutes.
Said extrusion section is advantageously connected to a vacuum extraction system so as to remove impurities, such as dissolved gases, light organic compounds and/or moisture, which can be present in the plastic fraction.
Said extrusion section can also advantageously comprise a filtration system for removing solid particles of undesirable size, for example with a size of greater than 200 μm and preferably with a size of greater than 40 μm, such as sand particles. If a diluent is used, the viscosity being able to decrease, it is possible to filter particles of smaller size, for example with a size of greater than 3 μm.
The plastic fraction is advantageously placed in contact with a hydrocarbon-based plastic diluent 107, derived from the hydroconversion process according to the invention or not, preferably derived from the hydroconversion process, within said extrusion section of extruder 10.
The use of a plastic diluent has the following advantages:
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- reducing the viscosity of the plastic fraction, notably allowing the diluted plastic fraction to be readily transported over greater distances;
- reducing the operating temperature of extruder 10, and optionally limiting thermal degradation of the polymer(s) in the plastic fraction. For example, it is possible to extrude, at least after the point(s) of placing in contact with the plastic diluent 107, from a temperature not more than 25° C. below the melting temperature of the plastic fraction;
- initiating dispersion of the polymer(s) of the plastic fraction in a low-viscosity phase so that they mix more readily with the heavy hydrocarbon fraction within the first hydroconversion reactor of the first hydroconversion section 20.
Separately to the introduction of the extruded plastic fraction, diluted or not, the heavy hydrocarbon fraction 101 is introduced into the first hydroconversion reactor, and the hydroconversion step (b) as described below is performed.
Prior to its introduction into the first hydroconversion reactor, the heavy hydrocarbon fraction 101 may be mixed with an entrained catalyst precursor 104, such that, upon formation of the entrained catalyst, notably by reaction with sulfur, the entrained catalyst will comprise a colloidal or molecular catalyst dispersed in the feedstock.
The entrained catalyst precursor may be chosen from any metal catalyst precursor known to those skilled in the art, which is capable of forming a colloidally or molecularly dispersed catalyst (i.e. the entrained catalyst) in the presence of hydrogen and/or H2S and/or any other source of sulfur, and which allows hydroconversion of the feedstock after injection into the first hydroconversion reactor.
The catalyst precursor is advantageously an oil-soluble catalyst precursor containing at least one transition metal.
The catalyst precursor preferably comprises an oil-soluble organometallic compound or complex.
The catalyst precursor may comprise an oil-soluble organometallic or bimetallic compound or complex comprising one or two of the following metals: Mo, Ni, V, Fe, Co or W, or mixtures of such compounds/complexes.
The oil-soluble catalyst precursor preferably has a decomposition temperature (temperature below which the catalyst precursor is substantially chemically stable) in a range from 100° C. to 350° C., more preferably in a range from 150° C. to 300° C., and most preferably in a range from 175° C. to 250° C.
The oil-soluble organometallic compound or complex is preferably chosen from the group consisting of molybdenum 2-ethylhexanoate, molybdenum naphthanate, vanadium naphthanate, vanadium octoate, molybdenum hexacarbonyl, vanadium hexacarbonyl, and iron pentacarbonyl. These compounds are nonlimiting examples of oil-soluble catalyst precursors.
More preferably, the catalyst precursor comprises Mo and, for example, comprises a compound chosen from the group consisting of molybdenum 2-ethylhexanoate, molybdenum naphthanate and molybdenum hexacarbonyl.
A currently preferred catalyst precursor comprises, or consists of, molybdenum 2-ethylhexanoate (also commonly known as molybdenum octoate).
Typically, molybdenum 2-ethylhexanoate contains 15% by weight of molybdenum and has a sufficiently high decomposition temperature or decomposition temperature range to avoid substantial thermal decomposition when mixed with a heavy hydrocarbon fraction at a temperature below 250° C.
A person skilled in the art may choose a mixing temperature profile that results in mixing of the chosen precursor without substantial thermal decomposition prior to colloidal or molecular catalyst formation.
Catalyst precursor 104, preferably an oil-soluble catalyst precursor, may be premixed with a hydrocarbon stream of diluent to form a dilute precursor mixture, as described in US2005/0241991, U.S. Ser. No. 10/822,553 or U.S. Ser. No. 10/941,353 and recalled below.
Catalyst precursor 104 may be premixed with a diluent to form a diluted precursor mixture, said premixing preferably being performed at a temperature below a temperature at which a substantial portion of the catalyst precursor begins to decompose, preferably between room temperature, e.g. 15° C., and 300° C., more preferably between 15° C. and 200° C., even more preferably between 50° C. and 200° C., even more preferably between 75° C. and 150° C., and even more preferably between 75° C. and 100° C., and advantageously for a period of time from 1 second to 30 minutes.
Typically, the catalyst precursor diluent may be a hydrocarbon-based oil composed of hydrocarbons of which at least 50% by weight, relative to the total weight of the hydrocarbon-based oil, have a boiling temperature of between 180° C. and 540° C. Examples of hydrocarbon-based diluents that are suitable for precursor dilution include, but are not limited to, vacuum gas oil known as “VGO” (which typically has a boiling range of 360° C. to 524° C.), settling oil or recycle oil (which typically has a boiling range of 360° C. to 550° C.), for example, FCC fluidized-bed catalytic cracking effluent, such as heavy cycle oil (HCO) or light cycle oil (LCO), pyrolysis oil from a hydrocracker, light diesel oil (which typically has a boiling range of 200° C. to 360° C.), atmospheric residues, vacuum residues (which typically have a boiling range of equal to or greater than 524° C.), deasphalted oils, and resins. The catalyst precursor diluent is preferably atmospheric residue, vacuum residue or VGO.
Next, the diluted precursor may be mixed with the heavy hydrocarbon fraction 101, preferably at a temperature between room temperature, e.g. 15° C., and 300° C., and advantageously for a period of time from 1 second to 30 minutes, preferably from 1 second to 10 minutes, and even more preferably in the range from 2 seconds to 3 minutes. In the present description, a mixing time (or residence time for mixing) of 1 second means instantaneous mixing.
The mass ratio of catalyst precursor 104 to hydrocarbon-based oil diluent is preferably in a range from about 1:500 to about 1:1, more preferably in the range from about 1:150 to about 1:2, and even more preferably in a range from about 1:100 to about 1:5 (e.g. 1:100, 1:50, 1:30, or 1:10).
Without mixing with a diluent, it is preferable to ensure that the components are mixed for a sufficient time to completely/intimately mix the catalyst precursor into the heavy hydrocarbon fraction before the entrained catalyst is formed. However, a long mixing time, for example 24 hours, may be prohibitively expensive for certain industrial operations.
Premixing the catalyst precursor 104 with a hydrocarbon-based diluent greatly facilitates thorough and intimate mixing of the precursor into the heavy hydrocarbon fraction, particularly in the relatively short period of time required for large-scale industrial operations to be economically viable.
The diluted precursor is preferably combined with the heavy hydrocarbon fraction and mixed for a sufficient time and in such a manner as to disperse the catalyst precursor throughout the heavy fraction so that the catalyst precursor is completely/intimately mixed with the heavy hydrocarbon fraction. In order to obtain sufficient mixing prior to colloidal or molecular catalyst formation, the diluted precursor and the heavy fraction are more preferably mixed for a period of time in the range from 1 second to 10 minutes, and even more preferably in the range from 2 seconds to 3 minutes. Increasing the vigor and/or shear energy of the mixing process generally reduces the time required to achieve complete/intimate mixture. Examples of mixing appliances that may be used for performing complete/intimate mixture of catalyst precursor 104 and heavy hydrocarbon fraction 101 comprise, without being limited thereto, high shear mixing, such as a mixture created in a pump with a rotor agitator or propeller, multiple static in-line mixers, multiple static in-line mixers in combination with high shear in-line mixers, multiple static in-line mixers in combination with high shear in-line mixers, multiple static in-line mixers in combination with high shear in-line mixers followed by recirculation pumping in the holding tank, combinations of the above appliances followed by one or more multi-stage centrifugal pumps.
The heavy hydrocarbon fraction 101 and the diluted precursor are preferably mixed and conditioned at a temperature in the range from 50° C. to 200° C., more preferably in the range from 75° C. to 175° C., prior to introduction of the heavy hydrocarbon fraction into the first hydroconversion reactor. Preferably, the gauge pressure is between 0 MPa and 25 MPa, more preferably between 0.01 MPa and 5 MPa.
The heavy hydrocarbon fraction 101, which may contain the entrained catalyst precursor, diluted or not, may be heated in at least one preheating device before being introduced into the hydroconversion reactor. This preheating may help to achieve a target temperature in the first hydroconversion reactor in the subsequent step (b). Preheating is preferably performed at a temperature of between 280° C. and 450° C., even more preferably between 300° C. and 400° C., and even more preferably between 320° C. and 365° C. This preheating may be performed at a temperature which is 100° C. lower, preferably 50° C. lower, than the hydroconversion temperature in the hydroconversion reactor. The absolute pressure during this preheating may be between atmospheric pressure (e.g. 0.101325 MPa) and 38 MPa, preferably between 5 MPa and 25 MPa, and preferably between 6 MPa and 20 MPa. Preheating advantageously causes the release of the sulfur contained in the heavy hydrocarbon fraction, which may combine with the metal of the catalyst precursor. The colloidal or molecular catalyst may form, or at least start to form, in situ in the heavy hydrocarbon fraction during this preheating step. In order to form the colloidal or molecular catalyst, sulfur must be available (e.g. as H2S) to combine with the metal of the dispersed catalyst precursor composition. The entrained catalyst may also be formed in the hydroconversion step (b).
In the case where the heavy hydrocarbon fraction comprises sulfur in sufficient amounts or in excess, the final activated catalyst may be formed in situ by heating said heavy fraction to a temperature sufficient to release the sulfur therefrom. A source of sulfur may thus be H2S dissolved in the heavy hydrocarbon fraction, or H2S contained in hydrogen recycled to the hydroconversion reactor, or H2S originating from sulfur-containing organic molecules present in the heavy hydrocarbon fraction or optionally previously introduced into said heavy fraction (e.g.: injection of dimethyl disulfide, thioacetamide, any sulfur-containing hydrocarbon feedstock of the type such as mercaptans, sulfides, sulfur-containing petroleum, sulfur-containing diesel oil, sulfur-containing vacuum distillate, sulfur-containing residue).
Thus, a source of sulfur may be sulfur compounds in the heavy hydrocarbon fraction or a sulfur compound added to said heavy fraction.
The temperature during the preheating of the heavy hydrocarbon fraction and/or in step (b) allows the formation of the metal sulfide catalyst.
The metal concentration of the catalyst, preferably Mo, in the feedstock (i.e. heavy hydrocarbon fraction and plastic fraction together) is preferably between 5 ppm and 500 ppm by weight of the feedstock, more preferably between 10 ppm and 300 ppm by weight, more preferably between 10 ppm and 175 ppm by weight, even more preferably between 10 ppm and 75 ppm by weight, and even more preferably between 10 ppm and 50 ppm by weight. Preferably, the colloidal or molecular catalyst comprises molybdenum disulfide.
Step (a2)Alternatively, in step (a) the plastic fraction in solid particulate form may be mixed with a plastic diluent in a mixing section and heated in a heating section so as to obtain an essentially liquid plastic fraction (e.g. at a temperature above the melting temperature of said plastic fraction, preferably between 60° C. and 295° C.), prior to its introduction into the first hydroconversion reactor, the heating step possibly being performed before or after mixing with the plastic diluent, and preferably after mixing with the plastic diluent.
Thus, step (a) may be a step (a2) of direct injection of the plastic fraction in essentially liquid form after said plastic fraction has been mixed with a plastic diluent 107 to form a slurry which is then heated so as to obtain an essentially liquid plastic fraction.
This variant notably has the advantage of using simple, low-cost equipment.
The plastic fraction in the form of solid particles 102 is first mixed with a plastic diluent 107 in a mixing section 11 to form a suspension 108, and said suspension 108 is then sent to a heating section 12 to be heated to a temperature higher than the melting temperature of said plastic fraction, so that the solid particles of the plastic fraction in suspension melt, and said heated plastic fraction 109 is introduced into the first hydroconversion reactor of the first hydroconversion section 20. Mixing of the plastic diluent 107 and the particulate plastic fraction 102 in the mixing section 11 is preferably performed at or close to atmospheric pressure.
Preferably, during the mixing step in the mixing section 11, the temperature is such that the suspension 108 has a kinematic viscosity of less than 0.3×10−3 m2/s, corresponding to the viscosity of a pumpable fluid. The temperature at this step is preferably lower than the temperature operated in the heating step described below, in the case where the mixing step is dissociated and precedes the heating step.
The mixing section 11 may comprise a mixing tank including dynamic blending means for placing in suspension, for example a stirrer and/or a recirculation pump.
On conclusion of the heating of the suspension 108, at least 90% by weight of the heated plastic fraction 109 is advantageously in liquid form, very advantageously at least 95% by weight, preferentially at least 98% by weight.
That which has been described for the temperature conditions of extruder 10 in step (a1) applies for the heating of the suspension in step (a2), and is thus not repeated here.
However, it is again pointed out that the heating temperature may also depend on the plastic diluent 107 used, such a plastic diluent in particular being able, depending on its nature, to allow the plastic fraction in suspension to melt at a lower temperature.
The heating section 12 comprises any heating means known to those skilled in the art which is capable of heating a suspended plastic fraction 108. Heating section 12 may comprise an oven comprising at least one heating compartment, and/or tubes in which suspension 108 flows, any type of suitable heat exchanger, etc.
According to one configuration, the mixing section 11 and the heating section 12 may form part of the same device configured to consecutively perform the mixing and then heating of step (a2).
Before it is introduced into the first hydroconversion reactor, the heated plastic fraction 109 is subjected to a pressurization step in order to be suited to the pressure operated in the first hydroconversion reactor, for example by means of a suitable pump. It may also be subjected to a filtration step directed, for example, toward removing solid particles from the plastic fraction which can form part of the impurities of the plastics, such as sand, glass, metals, certain additives known as fillers, and the like.
Separately to the introduction of the heated plastic fraction 109, the heavy hydrocarbon fraction 101 is introduced into the first hydroconversion reactor of the first hydroconversion section 20, and the hydroconversion step (b) as described below is performed.
Prior to its introduction into the first hydroconversion reactor, the heavy hydrocarbon fraction 101 may be mixed with an entrained catalyst precursor 104, such that, upon formation of the entrained catalyst, notably by reaction with sulfur, the entrained catalyst will comprise a colloidal or molecular catalyst dispersed in the feedstock. That which has been described on this subject in step (a1) similarly applies here and is not repeated.
According to another variant of the first embodiment of the process according to the invention, not shown, step (a) may be a step (a′2) of direct injection of the plastic fraction in essentially liquid form after said plastic fraction has been heated so as to obtain an essentially liquid plastic fraction, then mixed with a plastic diluent 107 to form a diluted plastic fraction introduced into the first hydroconversion reactor.
According to yet another variant, the mixing step and the heating step are performed simultaneously, the mixing and heating sections then forming part of one and the same device configured to simultaneously perform the mixing and the heating.
Step (a3)Alternatively, step (a) may be a step (a3) of direct injection of the suspended plastic fraction into the first hydroconversion reactor.
This variant notably has the advantage of using simple, low-cost equipment.
According to step (a3), the plastic fraction in the form of solid particles 102 is first sent to a mixer 13 to be mixed with a plastic diluent 107 to form a suspension 110, and said plastic fraction in the form of suspension 110 is then introduced into the first hydroconversion reactor of the first hydroconversion section 20.
The mixing of the plastic diluent 107 and of the plastic fraction 102 in the mixer is preferably performed at a temperature greater than or equal to room temperature, e.g. 15° C., and lower than the melting point of said plastic fraction (or lower than the melting point of the polymer which has the lowest melting point, if said plastic fraction includes a blend of polymers). A temperature slightly lower than the melting point of the plastic fraction may constitute the high limit for the mixing temperature, because the plastic diluent 107 used, depending on its nature, has an influence on the temperature at which the plastic fraction can be dissolved (in the case where the plastic diluent acts as a solvent).
According to one configuration, the mixing may be performed at a temperature of greater than or equal to 50° C. or even 75° C. and less than 170° C., for example well suited to the use of a VGO as plastic diluent and to a plastic fraction mainly including PP as polymer, or also at a temperature of greater than or equal to 150° C. and less than 170° C., for example well suited to the use of a vacuum residue as plastic diluent and to a plastic fraction mainly including PP as polymer.
According to one configuration, the mixing can be performed at a temperature of greater than or equal to 50° C. or even 75° C. and less than 140° C., or also performed at a temperature of greater than or equal to 50° C. or even 75° C. and less than 85° C., for example well suited to the use of a VGO as plastic diluent and to a plastic fraction mainly including PE as polymer.
According to one configuration, the mixing can be performed at a temperature of greater than or equal to 50° C. or even 75° C. and less than 270° C., or also performed at a temperature of greater than or equal to 50° C. or even 75° C. and less than 240° C., for example well suited to the use of a VGO as plastic diluent and to a plastic fraction mainly including PS as polymer, or else at a temperature of greater than or equal to 150° C. and less than 270° C., or even less than 240° C., for example well suited to the use of a vacuum residue as plastic diluent and to a plastic fraction mainly including PS as polymer.
The mixing may or may not be active. Examples of active mixing appliances that may be used comprise, without being limited thereto, high shear mixing, such as a mixture created in a pump with a rotor agitator or propeller, multiple static in-line mixers, multiple static in-line mixers in combination with high shear in-line mixers, multiple static in-line mixers in combination with high shear in-line mixers, multiple static in-line mixers in combination with high shear in-line mixers followed by recirculation pumping in the holding tank, combinations of the above appliances followed by one or more multi-stage centrifugal pumps.
Separately to the introduction of the plastic fraction in suspension 110, the heavy hydrocarbon fraction 101 is introduced into the first hydroconversion reactor of the first hydroconversion section 20, and the hydroconversion step (b) as described below is performed.
Prior to its introduction into the first hydroconversion reactor, the heavy hydrocarbon fraction 101 may be mixed with an entrained catalyst precursor 104, such that, upon formation of the entrained catalyst, notably by reaction with sulfur, the entrained catalyst will comprise a colloidal or molecular catalyst dispersed in the feedstock. That which has been described on this subject in step (a1) similarly applies here and is not repeated.
Prior to their introduction into the first hydroconversion reactor, the suspended plastic fraction 110 and the heavy hydrocarbon fraction 101 may undergo a pressurization step to be suitable for the pressure operated in the first hydroconversion reactor.
Step (a4)Alternatively, step (a) may be a step (a4) of directly injecting the plastic fraction into the hydroconversion reactor in the form of a suspension via the means for injecting the porous supported hydroconversion catalyst into said hydroconversion reactor.
This variant notably has the advantage of using existing particle injection means (the supported catalyst) in the reactor to inject the plastic fraction of the feedstock.
According to step (a4), the plastic fraction in the form of solid particles 102 is premixed with a plastic diluent 107 and with the first porous supported hydroconversion catalyst in a distribution and mixing box 14 to form a suspension 112, and said suspension 112 is then introduced into the first hydroconversion reactor of the first hydroconversion section 20 via means for injecting the catalyst into said reactor.
The distribution and mixing box 14 forms part of a device for withdrawing and injecting porous supported catalyst in the first hydroconversion reactor.
Preferably, the plastic fraction in the form of solid particles 102 is fed into the distribution and mixing box 14 intermittently.
The first hydroconversion reactor, like each ebullated bed or hybrid hydroconversion reactor used in the process according to the invention, comprises means for injecting and withdrawing the supported catalyst in said reactor.
Specifically, an essential aspect of the functioning of ebullated bed or hybrid reactors is the continuous replacement of the supported catalyst. Catalyst replacement is generally required in all hydrocarbon hydroconversion processes, as the supported catalyst deactivates mainly by deposition of metals contained in the feedstock, in the form of vanadium sulfide and nickel sulfide, and by coke deposition. Specifically, although ebullated bed technology allows the time between two conversion process stoppages to be increased by continuous catalyst renewal, compared with other technologies such as fixed-bed technology, it requires the implementation of a system for continuous catalyst renewal, with catalyst withdrawal and replenishment, for example on a daily basis. The spent catalyst, withdrawn from the reactor, can be sent to a regeneration zone in which the carbon and sulfur it contains are removed. It is also possible to send the spent catalyst withdrawn from the reactor to a rejuvenation zone, in which most of the metals deposited are removed, before sending the spent and rejuvenated catalyst to a regeneration zone, in which the carbon and sulfur it contains are removed. The regenerated or rejuvenated catalyst can subsequently be reintroduced into the reactor, optionally in combination with fresh catalyst, by the means for injecting the catalyst.
Typically, the means for injection and withdrawal of the supported catalyst include at least one pipe emerging in the expansion zone of the supported catalyst of the reactor for the introduction of the fresh (and/or regenerated and/or rejuvenated) supported catalyst into the expansion zone of the supported catalyst of the reactor and the withdrawal of spent catalyst from said zone. The introduction and withdrawal may be performed with the same pipe, or by means of separate pipes, then requiring at least two pipes, an injection pipe for the injection of supported catalyst into the reactor and a pipe for the withdrawal of the spent catalyst.
According to step (a3), the suspension 112, formed by the mixing of the particulate plastic fraction 102, the supported catalyst 111 and the plastic diluent 107 in the distribution and mixing box 14, is injected into the reactor via the supported catalyst injection means, in particular via a pipe connected at one end to said distribution and mixing box 14 and opening at its other end into the supported catalyst expansion zone of the first hydroconversion reactor.
Said pipe may comprise means for controlling the circulation of the injected slurry, for example valves and/or other elements such as pumps, storage tanks, etc. The means for injecting the supported catalyst into the first hydroconversion reactor are thus also means for injecting the plastic fraction as a suspension into said first reactor.
In a manner separate from the introduction of the suspension 112 including the plastic fraction and the first supported hydroconversion catalyst, the heavy hydrocarbon fraction 101 is introduced into the first hydroconversion reactor of the first hydroconversion section 20, and the hydroconversion step (b) as described below is performed.
Prior to its introduction into the first hydroconversion reactor, the heavy hydrocarbon fraction 101 may be mixed with an entrained catalyst precursor 104, such that, upon formation of the entrained catalyst, notably by reaction with sulfur, the entrained catalyst will comprise a colloidal or molecular catalyst dispersed in the feedstock. That which has been described on this subject in step (a1) similarly applies here and is not repeated.
Indirect injection: fractions mixed before injection into the hydroconversion reactor According to a second embodiment of the invention, alternative to the first embodiment, in step (a), the plastic fraction and the heavy hydrocarbon fraction of the feedstock (114, 117, 120, 122, 125) are introduced mixed into said at least one first hydroconversion reactor of the first hydroconversion section 20. Different variants may be performed, according to the alternative steps (a5) to (a9) described below in relation to
These variants are distinguished at a second level by the fact that the plastic fraction is in solid or slurry form (
This variant notably has the advantage of injecting into the first hydroconversion reactor a mixture including a plastic fraction already dispersed in the feedstock, allowing good suspension of the plastic fraction by means of the heavy hydrocarbon fraction for suspension, and increasing the rate of dissolution of the plastic fraction, where appropriate.
According to step (a5), the plastic fraction in the form of solid particles 102 is first mixed with the heavy hydrocarbon fraction 101 in a mixing device 15, forming a suspension 113.
Said mixing in mixing device 15 is preferably performed at a temperature greater than or equal to room temperature, e.g. 15° C., and lower than the melting point of said plastic fraction (or lower than the melting point of the polymer which has the lowest melting point, if said plastic fraction includes a blend of polymers).
Advantageously, the mixing may be performed at a temperature greater than or equal to 50° C. or even 75° C., and even greater than or equal to 150° C. and less than 170° C., or at a temperature greater than or equal to 150° C. and less than 170° C., for example well suited for the use of a plastic fraction including mainly PP as polymer.
Advantageously, the mixing may be performed at a temperature greater than or equal to 50° C. or even 75° C. and less than 140° C., or performed at a temperature greater than or equal to 50° C. or even 75° C. and less than 85° C., for example well suited for the use of a plastic fraction including mainly PE as polymer.
According to one configuration, the mixing may be performed at a temperature greater than or equal to 50° C. or even 75° C., or even greater than or equal to 150° C. and less than 270° C. or even less than 240° C., for example well suited for the use of a plastic fraction including mainly PS as polymer.
The mixing may or may not be active. The same examples of active mixing appliances, without limitation, that may be used are those already described in connection with step (a3) for mixing the plastic fraction with the plastic diluent.
Prior to its introduction into the mixing device 15, the heavy hydrocarbon fraction 101 may be mixed with an entrained catalyst precursor 104, so that upon formation of the entrained catalyst, notably by reaction with sulfur, the entrained catalyst will comprise a colloidal or molecular catalyst dispersed in the feedstock. That which has been described on this subject in step (a1) similarly applies here and is not repeated.
The suspension 113 is then heated in a heating device 16, so that the solid particles of the plastic fraction melt. Said suspension 113 is thus heated to a temperature above the melting point of said plastic fraction. On conclusion of the heating of suspension 113, at least 90% by weight of the plastic fraction of the feedstock 114 is advantageously in liquid form, very advantageously at least 95% by weight, preferentially at least 98% by weight.
Preferably, suspension 113 is heated so as to reach a target temperature in the first reactor. Heating is preferably performed at a temperature of between 280° C. and 450° C., even more preferably between 300° C. and 400° C., and even more preferably between 320° C. and 365° C. This preheating may be performed at a temperature which is 100° C. lower, preferably 50° C. lower, than the hydroconversion temperature in the hydroconversion reactor.
The heating section 16 comprises any heating means known to those skilled in the art which is capable of heating a suspended plastic fraction 113. The heating section 16 may comprise an oven comprising, for example, at least one heating compartment, and/or tubes in which the suspension flows, a mixer for mixing the feedstock with H2, any suitable type of heat exchanger, for example tubular or spiral heat exchangers in which the suspension flows, etc.
According to one configuration, the mixing section 15 and the heating section 16 may form part of a similarly configured device for consecutively performing the mixing and then heating of step (a5).
The feedstock 114, in essentially liquid form and including the plastic fraction and the heavy hydrocarbon fraction as a mixture, is then introduced into the first hydroconversion reactor of the first hydroconversion section 20, and the hydroconversion step (b) as described below is performed.
Preferably, a pressurization step is performed after the heavy hydrocarbon fraction has been mixed with the plastic fraction and before the heating section, so that feedstock 114 is suitable for the pressure operated in the first hydroconversion reactor.
Step (a6)Alternatively, step (a) may be an indirect injection step (a6), in which the plastic fraction is first mixed in solid form with a diluent before being blended with the heavy fraction. Said final mixture then forms a suspension, and constitutes the feedstock, which is heated so as to obtain an essentially liquid plastic fraction before the feedstock is introduced into the first hydroconversion reactor of the first hydroconversion section 20.
This second variant of the second embodiment of the process according to the invention, illustrated in
This variant notably offers the advantages mentioned for step (a5), and also better dissolution of the liquid fraction, where appropriate.
The operating conditions for this premixing in the first mixer 17, and also the type of mixture and associated device, are identical to those already described in relation to step (a3) in connection with mixing the plastic fraction and the plastic diluent, and are not repeated here.
The first suspension 115 is then mixed with the heavy hydrocarbon fraction 101 in a second mixer 18 to form a second suspension 116, in the same manner as that described in step (a5) above, and is not repeated here.
Prior to its introduction into the mixing device 15, the heavy hydrocarbon fraction 101 may be mixed with an entrained catalyst precursor 104, so that upon formation of the entrained catalyst, notably by reaction with sulfur, the entrained catalyst will comprise a colloidal or molecular catalyst dispersed in the feedstock. That which has been described on this subject in step (a1) similarly applies here and is not repeated.
Heating of the second suspension 116 in heating device 19 is also performed in the same manner as that described in step (a5) for heating of suspension 113, and allows the solid particles of the plastic fraction to melt. On conclusion of heating of the second suspension 116, at least 90% by weight of the plastic fraction of the feedstock is advantageously in liquid form, very advantageously at least 95% by weight, preferentially at least 98% by weight.
The feedstock 117, resulting from the heating of the second suspension 116 in the heating device 19, including the essentially liquid plastic fraction and the heavy hydrocarbon fraction as a mixture, is then introduced into the first hydroconversion reactor of the first hydroconversion section 20, and the hydroconversion step (b) as described below is performed.
Step (a7)Alternatively, step (a) may be an indirect injection step (a7), in which the plastic fraction is heated so as to be in a substantially liquid form before being mixed with the heavy hydrocarbon fraction.
The advantage of this variant is notably that it avoids the management of suspension of the plastic fraction, and notably dispenses with the need for the associated mixing equipment.
According to step (a7), the plastic fraction in the form of solid particles 102 is first heated in a melting device 21 for the purpose of melting said plastic fraction. To do this, the plastic fraction is heated to a temperature above the melting temperature of said plastic fraction.
Advantageously, at least 80% by weight of the plastic fraction is in liquid form on conclusion of this heating, very advantageously at least 90% by weight, preferentially at least 95% by weight, or even 98% by weight.
That which has been described for the temperature conditions of extruder 10 in step (a1) applies for the heating of the plastic fraction in liquefaction device 21 in this step (a7), and is thus not repeated here.
Melting device 21 comprises any heating means known to those skilled in the art that is capable of melting a solid plastic fraction. Melting device 21 may comprise an oven, a heated pot, etc. Melting device 21 may comprise mixing means for blending existing phases during melting.
The melting device may be an extruder as described in step (a1).
The molten plastic fraction 118 is then mixed with the heavy hydrocarbon fraction 101 in a mixer 22, to form a feedstock 119 which is then introduced into the first hydroconversion reactor of the first hydroconversion section 20, and the hydroconversion step (b) as described later is performed.
Said mixing in mixer 22 is preferably performed at a temperature of between 85° C., or even 100° C., and 350° C., preferably between 150° C. and 250° C. The temperature is advantageously adjusted according to the viscosity of the mixture.
Prior to its introduction into the mixing device 22, the heavy hydrocarbon fraction 101 may be mixed with an entrained catalyst precursor 104, so that upon formation of the entrained catalyst, notably by reaction with sulfur, the entrained catalyst will comprise a colloidal or molecular catalyst dispersed in the feedstock. That which has been described on this subject in step (a1) similarly applies here and is not repeated.
The entrained catalyst precursor 104 may also be mixed with the feedstock 119 coming from the mixer 22, prior to its introduction into the first hydroconversion reactor, in addition to or alternatively to mixing with the heavy hydrocarbon fraction 101. In this case, the mixing will be similar to that which has been described for mixing with the heavy hydrocarbon fraction 101.
Step (a8)Alternatively, step (a) may be an indirect injection step (a8), in which the plastic fraction is premixed in solid form with a plastic diluent and then heated so as to be in substantially liquid form before being mixed with the heavy hydrocarbon fraction.
This fourth variant of the second embodiment of the process according to the invention, illustrated in
This variant notably has the advantage of good dispersion and/or good dissolution of the plastic fraction, and provides greater flexibility for the mixing with the heavy hydrocarbon fraction, notably with regard to a targeted viscosity.
The operating conditions for this premixing in premixer 17, and also the type of mixture and associated device, are identical to those already described in connection with step (a3) and (a6) in relation to the mixing of the plastic fraction and the plastic diluent, and are not repeated here.
The suspension 120 is then heated in a heating device 23, to a temperature above the melting temperature of said plastic fraction, so that the solid particles of the plastic fraction in suspension melt.
On conclusion of the heating of suspension 120, at least 90% by weight of the plastic fraction is advantageously in liquid form, very advantageously at least 95% by weight, preferentially at least 98% by weight.
That which has been described for the temperature conditions of extruder 10 in step (a1) applies for the heating of suspension 120 in step (a8), and is thus not repeated here.
However, it is again pointed out that the heating temperature may also depend on the plastic diluent 107 used, such a diluent in particular being able, depending on its nature, to allow the plastic fraction in suspension to melt at a lower temperature.
The heating section 23 comprises any heating means known to those skilled in the art which is capable of heating a suspended plastic fraction 120. Heating section 23 may comprise an oven comprising at least one heating compartment, and/or tubes in which suspension 120 flows, any type of suitable heat exchanger, etc.
According to one configuration, the mixing section 17 and the heating section 23 may form part of the same device configured to consecutively perform the mixing and then heating of step (a8).
The molten diluted plastic fraction 121 is then mixed with the heavy hydrocarbon fraction 101 in a mixer 22 in the same manner as described in step (a7) for mixer 22, to form a feedstock 122 which is then introduced into the first hydroconversion reactor of the first hydroconversion section 20, and the hydroconversion step (b) as described later is performed.
Prior to its introduction into the mixer 22, the heavy hydrocarbon fraction 101 may be mixed with an entrained catalyst precursor 104, so that upon formation of the entrained catalyst, notably by reaction with sulfur, the entrained catalyst will comprise a colloidal or molecular catalyst dispersed in the feedstock. That which has been described on this subject in step (a1) similarly applies here and is not repeated.
The entrained catalyst precursor 104 may also be mixed with the feedstock 122 coming from the mixer 22, prior to its introduction into the first hydroconversion reactor, in addition to or alternatively to mixing with the heavy hydrocarbon fraction 101. In this case, the mixing will be similar to that which has been described for mixing with the heavy hydrocarbon fraction 101.
The entrained catalyst precursor 104 may also be mixed with the liquid plastic fraction 121 prior to its mixing with the heavy hydrocarbon fraction in the mixer 22, in addition to or alternatively to mixing of the precursor with the heavy hydrocarbon fraction 101 or with the feedstock 122. In this case, the mixing will be similar to that which has been described for mixing with the heavy hydrocarbon fraction 101.
Step (a9)Alternatively, step (a) may be an indirect injection step (a9), in which the plastic fraction is heated so as to be in a substantially liquid form and then mixed with a diluent before being mixed with the heavy hydrocarbon fraction.
This variant notably offers the advantage of good dispersion and/or good dissolution of the plastic fraction.
According to step (a9), the plastic fraction in the form of solid particles 102 is first heated in a melting device 24 so as to melt said plastic fraction, in the same manner as described in step (a7). Thus, to do this, the plastic fraction is heated to a temperature above the melting temperature of said plastic fraction. Advantageously, at least 80% by weight of the plastic fraction is in liquid form on conclusion of this heating, very advantageously at least 90% by weight, preferentially at least 95% by weight, or even 98% by weight.
That which has been described for the temperature conditions of extruder 10 in step (a1) applies for the heating of the plastic fraction in melting device 24 in this step (a9), and is thus not repeated here.
Melting device 24 is identical to that which has been described in step (a7) for melting device 21, and is not repeated here.
The molten plastic fraction 123 is then mixed with a plastic diluent 107 in a first mixer 25, to form a diluted molten plastic fraction 124.
Said mixing in the first mixer 25 is preferably performed at a temperature above the melting point of the plastic fraction (for example above 85° C., or even above 100° C.) and below or equal to 350° C., and preferably between 150° C. and 250° C.
The first mixer may comprise a static mixer or a dynamic mixer such as a stirred tank, and preferably comprises a static mixer.
The diluted molten plastic fraction 124 is then mixed with the heavy hydrocarbon fraction 101 in a second mixer 26, to form a feedstock 125 which is then introduced into the first hydroconversion reactor of the first hydroconversion section 20, and the hydroconversion step (b) as described below is performed.
Said mixing in mixer 26 is preferably similar to that described in step (a7) for mixer 22.
Prior to its introduction into the mixing device 26, the heavy hydrocarbon fraction 101 may be mixed with an entrained catalyst precursor 104, so that upon formation of the entrained catalyst, notably by reaction with sulfur, the entrained catalyst will comprise a colloidal or molecular catalyst dispersed in the feedstock. That which has been described on this subject in step (a1) similarly applies here and is not repeated.
The entrained catalyst precursor 104 may also be mixed with the diluted molten plastic fraction 124 prior to its mixing with the heavy hydrocarbon fraction in the mixer 26, in addition to or alternatively to mixing of the precursor with the heavy hydrocarbon fraction 101. In this case, the mixing will be similar to that which has been described for mixing with the heavy hydrocarbon fraction 101.
The entrained catalyst precursor 104 may also be mixed with the hydrocarbon-based diluent, as already described above in connection with step (a1) and
The feedstock (101, 102, 114, 117, 119, 122, 125) is introduced, whether its component fractions are separated or mixed, into the first hydroconversion reactor of the first hydroconversion section 20, together with hydrogen. Said first reactor comprises a first porous supported hydroconversion catalyst.
The first hydroconversion step (b) is performed under conditions affording a first hydroconverted effluent 105. Said first hydroconverted effluent 105 contains the conversion products; notably, said first effluent has a reduced content of hydrocarbons with a boiling point of at least 300° C. Said first hydroconverted effluent 105 may also have a reduced content of sulfur, and/or metals, and/or nitrogen, and/or Conradson carbon, and/or asphaltenes, depending on the reactions performed in the first hydroconversion reactor.
Step (b) is preferably performed at an absolute pressure of between 2 MPa and 38 MPa, more preferably between 5 MPa and 25 MPa, and even more preferably between 6 MPa and 20 MPa, at a temperature of between 300° C. and 550° C., more preferentially between 350° C. and 500° C., and preferably between 370° C. and 450° C.
The hourly space velocity (HSV) relative to the volume of each reactor is preferably between 0.05 h−1 and 10 h−1. According to a preferred embodiment, the HSV is between 0.1 h−1 and 10 h−1, more preferentially between 0.1 h−1 and 5 h−1, even more preferentially between 0.15 h−1 and 2 h−1, and even more preferably between 0.15 h−1 and 1 h−1. According to another embodiment, the HSV is between 0.05 h−1 and 0.09 h−1.
The amount of hydrogen mixed with the feedstock is preferably between 50 and 5000 normal cubic meters (Nm3) per cubic meter (m3) of liquid feedstock, preferably between 100 Nm3/m3 and 2000 Nm3/m3 and very preferably between 200 Nm3/m3 and 1000 Nm3/m3. The first hydroconversion section 20 comprises one or more ebullated or hybrid bed reactors, containing at least one first supported hydroconversion catalyst, the reactors possibly being arranged in series and/or in parallel. In this step, at least one first supported hydroconversion catalyst is thus maintained in the reactor(s). According to one or more embodiments of the invention, the first hydroconversion section 20 includes one or more hydroconversion reactors, which can be in series and/or in parallel, operating as an ebullated bed, as used for the H-Oil™ process, as described, for example, in patents U.S. Pat. No. 4,521,295 or U.S. Pat. No. 4,495,060 or U.S. Pat. No. 4,457,831 or U.S. Pat. No. 4,354,852, in the paper Aiche, Mar. 19-23, 1995, Houston, Texas, paper number 46d, “Second generation ebullated bed technology”, or in chapter 3.5, “Hydroprocessing and Hydroconversion of Residue Fractions”, of the work “Catalysis by Transition Metal Sulfides”, published by Technip in 2013. According to this or these embodiments, each reactor is operated as a fluidized bed known as an ebullated bed. Each reactor advantageously includes a recirculation pump which makes it possible to maintain the porous supported solid catalyst as an ebullated bed by continuous recycling of at least a part of a liquid fraction withdrawn at the upper part of the reactor and reinjected at the lower part of the reactor.
The ebullated bed reactor preferably includes at least one inlet orifice located at or near the lower part of the reactor through which the feedstock is introduced together with the hydrogen, and in particular two inlet orifices in the case where the plastic fraction of the feedstock is introduced separately from the heavy hydrocarbon fraction, and an outlet orifice at or near the upper part of the reactor through which the first hydroconverted effluent 105 is withdrawn. The reactor also preferably comprises an inlet and an outlet for the supported catalyst as already described previously in connection with the means for injection and withdrawal of the supported catalyst. The ebullated bed reactor also includes an expanded catalyst zone comprising the porous supported catalyst. The ebullated bed reactor also comprises a lower zone devoid of supported catalyst located below the expanded catalyst zone, and an upper zone devoid of supported catalyst located above the expanded catalyst zone. The feedstock in the ebullated bed reactor is continuously recirculated from the upper zone free of supported catalyst to the lower zone free of supported catalyst by means of a recycle pipe in communication with an ebullition pump. Preferably, a funnel-shaped recycle pan is located at the upper part of the recycle pipe, through which pan the feedstock is sucked from the upper zone free of supported catalyst. The internal recycled feedstock is mixed with “fresh” feedstock and additional hydrogen gas.
The first supported hydroconversion catalyst used in the first hydroconversion step (b) may contain one or more elements from groups 4 to 12 of the Periodic Table of the Elements, which may or may not be deposited on a support. Use may advantageously be made of a catalyst comprising an amorphous support, such as silica, alumina, silica-alumina, titanium dioxide or combinations of these structures, and very preferably alumina.
The first supported catalyst may contain at least one non-noble group VIII metal chosen from nickel and cobalt, preferably nickel, said group VIII element preferably being used in combination with at least one group VIB metal chosen from molybdenum and tungsten; preferably, the group VIB metal is molybdenum.
In the present description, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, Editor in Chief D. R. Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification.
Advantageously, the first supported hydroconversion catalyst used in the first hydroconversion step (b) comprises an alumina support and at least one group VIII metal chosen from nickel and cobalt, preferably nickel, and at least one group VIB metal chosen from molybdenum and tungsten, preferably molybdenum. Preferably, the first supported hydroconversion catalyst comprises nickel as group VIII element and molybdenum as group VIB element.
The content of non-noble group VIII metal, in particular of nickel, is advantageously between 0.5% and 10%, expressed as weight of metal oxide (in particular NiO), and preferably between 1% and 6% by weight, and the content of group VIB metal, in particular molybdenum, is advantageously between 1% and 30%, expressed as weight of oxide of the metal (in particular molybdenum trioxide MoO3), and preferably between 4% and 20% by weight. The contents of metals are expressed as weight percentages of metal oxide relative to the weight of the catalyst.
This first supported catalyst is advantageously used in the form of extrudates or beads. The beads have, for example, a diameter of between 0.4 mm and 4.0 mm. The extrudates have, for example, a cylindrical shape with a diameter of between 0.5 mm and 4.0 mm and with a length of between 1 mm and 5 mm. The extrudates may also be objects with a different shape, such as trilobes, tetralobes, which are regular or irregular, or other multilobes. Porous supported catalysts of other forms may also be used. The size of these various forms of porous supported catalysts can be characterized by means of the equivalent diameter. The equivalent diameter is defined as six times the ratio of the volume of the particle to the external surface area of the particle. The porous supported, catalyst used in the form of extrudates, beads or other forms, thus has an equivalent diameter of between 0.4 mm and 4.4 mm. These catalysts are well known to those skilled in the art.
According to one or more embodiments of the invention, the first hydroconversion section 20 includes one or more hybrid bed reactors (i.e. hybrid ebullated-entrained beds), simultaneously including at least one first supported hydroconversion catalyst which is maintained in the reactor and at least one entrained catalyst which enters the reactor with the feedstock and is entrained out of the reactor with the effluents. In this case, as already described above in connection with step (a), an entrained catalyst precursor has been introduced before the feedstock is injected into the first hydroconversion reactor, and a colloidal or molecular catalyst, also known as a dispersed, entrained or slurry catalyst, may have formed upstream or in situ in the hybrid bed hydroconversion reactor. These entrained catalysts are well known to those skilled in the art.
The hybrid bed reactor comprises a solid phase which includes a porous supported catalyst in the form of an expanded bed, a liquid hydrocarbon-based phase including the colloidal or molecular catalyst-containing feedstock dispersed therein, and a gaseous phase comprising hydrogen.
The hybrid bed reactor is an ebullated bed hydroconversion reactor as described above, but comprising, in addition to the porous supported catalyst in the form of an expanded bed held in the reactor, the molecular or colloidal catalyst entrained out of the reactor with the hydroconverted liquid effluent 105.
According to one or more embodiments, the functioning of the hybrid bed hydroconversion reactor is based on that of the ebullated bed reactor already described, and additionally involves the colloidal or molecular catalyst being dispersed throughout the feedstock into the hybrid bed reactor, including both in the expanded catalyst zone and in the supported catalyst-free zones, and thus available to stimulate upgrading reactions in what constitute catalyst-free zones in conventional ebullated bed reactors.
The presence of colloidal or molecular catalyst in the hybrid bed reactor provides additional catalytic hydrogenation activity, both in the expanded catalyst zone, in the recycle pipe, and in the lower and upper supported catalyst-free zones. The capping of free radicals outside the porous supported catalyst minimizes the formation of sediments and coke precursors, which are often responsible for the deactivation of the supported catalyst. This may allow a reduction in the amount of porous supported catalyst that would otherwise be required to perform a desired hydroconversion reaction. This may also reduce the rate at which the porous supported catalyst needs to be withdrawn and replenished.
In one of the embodiments of the process according to the invention, a different first hydroconversion supported catalyst may be used in each reactor of the first hydroconversion section, the supported catalyst specific to each reactor being suitable for the feedstock sent to that reactor. In one of the embodiments of the process according to the invention, several types of first supported catalyst are used in each reactor.
As is known, and for example described in patent FR3033797, the first hydroconversion supported catalyst, when spent, may be partly replaced with fresh supported catalyst, and/or spent supported catalyst but of higher catalytic activity than the spent supported catalyst to be replaced, and/or regenerated supported catalyst, and/or rejuvenated supported catalyst (catalyst coming from a rejuvenation zone in which most of the deposited metals are removed, before sending the spent and rejuvenated catalyst to a regeneration zone in which the carbon and sulfur it contains are removed, thus increasing the activity of the catalyst), by removing the spent supported catalyst preferably at the bottom of the reactor, and by introducing the replacement supported catalyst either at the top or at the bottom of the reactor. This replacement of spent catalyst is preferably performed at regular time intervals, and preferably in bursts or virtually continuously. This withdrawal and replacement is performed using a withdrawal and injection device advantageously allowing continuous functioning of this hydroconversion step. An example of such a device has already been described in connection with step (a), which may also allow the plastic fraction to be introduced according to a specific implementation (see step (a4)).
By means of this supported catalyst withdrawal/injection operating mode, it is thus not necessary to stop the unit to change the spent catalyst, nor to increase reaction temperatures along the cycle to compensate for deactivation. Furthermore, working under constant operating conditions makes it possible to obtain constant product yields and qualities along the cycle. Thus, due to the fact that the supported catalyst is kept stirring by a significant recycling of liquid, the pressure drop over the reactor remains low and constant, and the reaction exotherms are rapidly averaged over the catalytic bed, which is thus virtually isothermal and does not require the injection of cooling streams (quenches).
According to one or more embodiments, when step (b) is performed in one or more hybrid bed reactors, the feedstock or entrained catalyst precursor may be premixed with an organic additive, before the feedstock is introduced into the first hydroconversion reactor of the first hydroconversion section 20, so as notably to minimize fouling of the facilities prior to hydroconversion in the hybrid bed reactor(s). Without being bound by any theory, the organic additive, as a mixture with the feedstock, allows improved solubility of the catalyst precursor entrained in the feedstock, avoiding or reducing fouling in particular due to metal deposits in the facilities upstream of the hydroconversion reactor, such as in heating devices, and thus improving the dispersion of the entrained catalyst, thus generating increased availability of metal active sites, promoting the hydrogenation of free radicals which are precursors of coke and sediments, and generating a substantial reduction in fouling of the facilities. Said organic additive, which is neither a catalyst nor a catalyst precursor (e.g. it contains no metal), has at least one carboxylic acid function and/or at least one ester function and/or at least one acid anhydride function. It preferably comprises at least 6, or even at least 8 carbon atoms, and more preferably at least 8 carbon atoms. For example, the organic additive may be 2-ethylhexanoic acid, naphthenic acid, caprylic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, ethyl octanoate, ethyl 2-ethylhexanoate, 2-ethylhexyl 2-ethylhexanoate, benzyl 2-ethylhexanoate, diethyl adipate, dimethyl adipate, bis(2-ethylhexyl) adipate, dimethyl pimelate, dimethyl suberate, monomethyl suberate, hexanoic anhydride, caprylic anhydride, and mixtures thereof. The organic additive is preferably added during the mixing step so that the mole ratio of organic additive to active metal(s) of the catalyst precursor composition (e.g. Mo) is between 0.1:1 and 20:1, more preferably between 0.75:1 and 7:1, and even more preferably between 1:1 and 5:1.
(c) Optional Intermediate Separation StepAccording to one or more preferred embodiments, the process also comprises a separation step (c), which separates some or all of the first hydroconverted effluent 105, to produce at least two cuts, one of which is a heavy cut boiling predominantly at a temperature greater than or equal to 350° C.
The other cut(s) are one or more light and intermediate cuts. The light cut thus separated contains mainly gases (H2, H2S, NH3 and C1-C4), naphtha (cut boiling at a temperature below 150° C.), kerosene (cut boiling between 150° C. and 250° C.), and at least some diesel (fraction boiling between 250° C. and 375° C.). The light cut may then be sent at least in part to a fractionation unit (not represented in the figures) where the light gases are extracted from said light cut, for example by passing through an expansion vessel. The hydrogen gas thus recovered, which may have been sent to a purification and compression facility, may advantageously be recycled into the first hydroconversion step (b), and/or the second hydroconversion step (d) if performed. The recovered hydrogen gas may also be used in other refinery facilities.
The optional separation step (c) is performed in a separation section (not represented in the figures), which comprises any separation means known to those skilled in the art. Said separation section may comprise one or more expansion vessels arranged in series, and/or one or more steam and/or hydrogen stripping columns, and/or an atmospheric distillation column, and/or a vacuum distillation column, and preferably consists of a single expansion vessel, commonly referred to as a “hot separator”.
(d) Optional Second Hydroconversion StepAccording to one or more preferred embodiments (not shown in the figures), the process also comprises a second hydroconversion step, in at least one second ebullated bed or hybrid bed reactor comprising a second porous supported catalyst, in the presence of hydrogen, of some or all of the first effluent 105 resulting from step (b), or optionally of the heavy cut from step (c). This second hydroconversion step is performed so as to produce a second hydroconverted effluent. Said second hydroconverted effluent advantageously contains a larger amount of conversion products than the first hydroconverted effluent, and notably a notably lower content of hydrocarbons with a boiling point of at least 300° C. The second hydroconverted effluent may have a reduced Conradson carbon residue, and optionally a reduced amount of sulfur, and/or nitrogen, and/or metals, and/or asphaltenes.
The second hydroconversion step is performed in a similar manner to that described for the first hydroconversion step (b), and is not repeated here. This applies notably to the operating conditions, the equipment used and the porous supported hydroconversion catalysts used, with the exception of the details mentioned below.
As with the first hydroconversion step (b), the second hydroconversion step is performed in at least a second ebullated or hybrid bed reactor. It is preferably performed in one or more ebullated bed reactors if the first hydroconversion step is also performed in one or more ebullated bed reactors, and it is preferably performed in one or more hybrid bed reactors if the first hydroconversion step is performed in one or more hybrid bed reactors.
In this second hydroconversion step, the operating conditions may be similar to or different from those in hydroconversion step (d), with the temperature remaining in the range between 300° C. and 550° C., preferably between 350° C. and 500° C., more preferably between 370° C. and 450° C., more preferably between 400° C. and 440° C., and even more preferably between 410° C. and 435° C., and the amount of hydrogen introduced into the reactor remains in the range between 50 Nm3/m3 and 5000 Nm3/m3 of liquid feedstock, preferably between 100 Nm3/m3 and 3000 Nm3/m3, and even more preferably between 200 Nm3/m3 and 2000 Nm3/m3. The other pressure and HSV parameters are in identical ranges to those described for the hydroconversion step (d).
The operating temperature in the second hydroconversion step (d) may be higher than the operating temperature in the first hydroconversion step (b). This may allow more complete conversion of the as yet unconverted feedstock. Hydroconversion of liquid products from the first hydroconversion step and feedstock conversion are enhanced, as are the hydrotreating reactions such as hydrodesulfurization and hydrodeazotization, interalia. Operating conditions are chosen to minimize the formation of solids (e.g. coke).
The second porous supported hydroconversion catalyst used in the second hydroconversion reactor may be the same as that used in the first hydroconversion reactor(s) of the first hydroconversion section 20, or may be another porous supported catalyst also suitable for hydroconversion of the treated feedstock, as defined for the first supported catalyst used in the first hydroconversion step (b).
(e) Fractionation StepThe first hydroconverted effluent 105 from the hydroconversion step (b), or from the second hydroconversion step (d) if such a step is performed, then undergoes at least in part a fractionation step (e) in a fractionation section 30.
This fractionation step (e) separates some or all of said hydroconverted effluent into several fractions, including at least one heavy liquid product 106b boiling predominantly at a temperature above 350° C., preferably above 500° C. and more preferably above 540° C. The heavy liquid product 106b contains a part boiling at a temperature above 540° C., called the residual fraction (or vacuum residue), which is the unconverted part. The heavy liquid product 106b may contain a portion of the gas oil fraction boiling between 250° C. and 375° C. and a portion boiling between 375° C. and 540° C. (also known as vacuum distillate).
This fractionation step thus produces at least two products including the heavy liquid product 106b as described above, the other product(s) 106a being light and intermediate cut(s).
The fractionation section 30 comprises any separation means known to those skilled in the art.
Fractionation section 30 may thus comprise one or more of the following separation units: one or more flash vessels arranged in series, preferably a sequence of at least two successive flash vessels, one or more vapor and/or hydrogen stripping columns, an atmospheric distillation column, a vacuum distillation column.
According to one or more embodiments, this fractionation step (e) is performed by a sequence of at least two successive flash vessels.
According to one or more other embodiments, this fractionation step (e) is performed by one or more steam and/or hydrogen stripping columns.
According to one or more preferred embodiments, this fractionation step (e) is performed by an atmospheric distillation column, and more preferentially by an atmospheric distillation column and a vacuum column receiving the atmospheric residue.
According to the most preferred embodiment(s), this fractionation step (e) is performed by one or more flash vessels, an atmospheric distillation column and a vacuum column receiving the atmospheric residue. This configuration allows the size of any downstream deasphalter to be reduced, thus minimizing investment and operating costs.
The fractionation section 30 may also receive, in addition to some or all of the hydroconverted liquid effluent, one or more additional effluents, such as one or more hydrocarbon feedstocks external to the process (e.g. atmospheric and/or vacuum distillates). (e.g. atmospheric and/or vacuum distillates, atmospheric and/or vacuum residues), part of the heavy cut from the separation step (c) if performed, part of one or more of the intermediate cuts from the fractionation step (e), part of a DAO or a light or heavy fraction of a DAO if a deasphalting step (f1) is performed.
(f) Subsequent Treatment Step(s)One or more subsequent steps (f) of treatment of the heavy liquid product 106b and/or of the other product(s) resulting from the fractionation step (e) may be performed.
The various hydrocarbon-based products that may result from fractionation step (e) in fractionation means 30 may be sent to various processes in the refinery, illustrated in the figures under general reference 40, and the details of these post-treatments are not described here as they are generally known to those skilled in the art. For example, gas fractions, naphtha, middle distillates, VGO, DAO may be sent to hydrotreating, steam cracking, fluidized bed catalytic cracking (FCC), hydrocracking, lubricant oil extraction, etc. processes. Residues (atmospheric or vacuum residues) may also be post-treated, or used for other applications such as gasification, production of bitumen, heavy fuel oils, etc. Heavy fractions, including residues, can also be recycled into the hydroconversion process, for example into a hydroconversion reactor in step (b) or (d).
According to one or more embodiments, the hydroconversion process includes a step (f1) of deasphalting, in a deasphalter, part or all of said heavy liquid product 106b obtained in fractionation step (e), with at least one hydrocarbon-based solvent, to produce a deasphalted oil DAO and a residual asphalt (“SDA” Solvent DeAsphalting step).
Such a deasphalting step (f1) is performed under conditions well known to those skilled in the art. Reference may thus be made to the article by Billon et al. published in 1994 in Volume 49, No. 5 of the Revue de l'Institut Français du Pétrole, pages 495 to 507, to the book “Raffinage et conversion des produits lourds du pétrole” by J. F. Le Page, S. G. Chatila and M. Davidson, Edition Technip, pages 17-32 or to U.S. Pat. Nos. 4,239,616, 4,354,922, 4,354,928, 4,440,633, 4,536,283, and 4,715,946. Deasphalting may be performed in one or more mixer-settlers or in one or more extraction columns. The deasphalter thus comprises at least one mixer-settler or at least one extraction column. Deasphalting is a liquid-liquid extraction generally performed at an average temperature of between 60° C. and 250° C. with at least one low-boiling hydrocarbon-based solvent, preferably a paraffinic solvent, preferentially heavier than propane, preferably containing from 3 to 7 carbon atoms. Preferred solvents include propane, butane, isobutane, pentane, isopentane, neopentane, hexane, isohexanes, C6 hydrocarbons, heptane, C7 hydrocarbons, more or less apolar light gasolines, and also mixtures obtained from the abovementioned solvents. Preferably, the solvent is butane, pentane or hexane, and also mixtures thereof. The solvent/feedstock (volume/volume) ratios entering the deasphalter are in general between 3/1 and 16/1, and preferably between 4/1 and 8/1. Preferably, the deasphalter comprises at least one extraction column, and preferably only one (e.g. as employed in the Solvahl™ process) in which the solvent/feedstock (volume/volume) ratios entering the deasphalter are preferably low, typically between 4/1 and 8/1, or even between 4/1 and 6/1. The deasphalter produces a DAO practically free of C7 asphaltenes, said C7 asphaltene content preferably being less than 2% by weight, more preferentially less than 0.5% by weight, even more preferentially less than 0.05% by weight, and a residual asphalt concentrating the majority of the impurities in the residue, said residual asphalt being drawn off. The DAO yield is generally between 40% and 95% by weight, depending on the operating conditions and solvent used, and on the feedstock sent to the deasphalter, notably the quality of the heavy liquid product 106b.
When it is desired to recycle part of the heavy residue fraction (e.g. part of the heavy liquid product 106b and/or part of the residual asphalt, or part of the DAO) into the hydroconversion system (e.g. into the first hydroconversion reactor or upstream), it may be advantageous, in the case of hybrid bed reactor functioning, to leave the entrained catalyst in the residues, and/or the residual asphalt fraction. A purge on the recycled stream may be performed, in general to prevent certain compounds from accumulating to excessive levels.
EXAMPLESThe examples below are intended to demonstrate certain performances of the process according to the invention.
These examples illustrate the possibility of chemically recycling plastics in an H-Oil™ type ebullated bed hydroconversion process, which converts them into lighter hydrocarbons, which may in turn serve as raw materials for new plastics or as bases for manufacturing fuels, lubricants or any other product derived from petroleum refining. The method of insertion of these plastics, initially in the form of solid particles which are dispersed, melted and dissolved in a mixer prior to the reaction, is also illustrated. The experiments in this example were performed in a closed (“batch”) reactor, representative of the H-Oil™ process.
Example 1 is a comparative example illustrating the performance of the hydroconversion process for a plastic-free feedstock.
Example 2 illustrates the performance of an H-Oil™ process with a feedstock including the plastic and heavy fractions as defined below, with implementation of a dispersion/dissolution pre-step allowing conversion of said plastic into lighter hydrocarbons of the light, middle or vacuum distillate type, which may be upgraded in the refinery.
Feedstock:The heavy fraction (I) of the feedstock is a “straight-run” vacuum residue (RSV-SR) derived directly from the distillation of a petroleum crude. The plastic fraction (II) of the feedstock is a polyethylene from conventional sorting channels, which has been pretreated and contains less than 0.5% of mineral additives. It is in the form of solid particles ranging in size from 500 μm to a maximum of 5 mm.
The main characteristics of these two fractions of the feedstock are shown in Table 1 below.
The operating conditions for these two examples are summarized in Table 2 below.
The batch reactor is charged with 100% RSV-SR (fraction I of the feedstock), previously heated to 50° C.-100° C. to make it less viscous. The reactor is closed, purged with nitrogen and purged with hydrogen, then pressurized with hydrogen up to a pressure of about 3 MPa. The reactor is then heated to 100° C. At this temperature, stirring is started at 500 rpm. Gradually, the temperature is raised from 100° C. to the reaction temperature and, in parallel, stirring is gradually increased from 500 to 1000 rpm. When the reaction temperature is reached, the pressure in the reactor is instantly adjusted to the target value by adding H2. At this point, the reaction time is counted down. At the end of the experiment time, the reactor is rapidly cooled to stop the reaction, stirring is stopped when the reactor is at room temperature, and the liquid effluent and gases are collected for analysis.
Procedure of Example 2The batch reactor is first charged with the 90% RSV-SR (fraction I of the feedstock), then the 10% plastics (fraction II of the feedstock) are added and manually dispersed for a few seconds in the RSV-SR, previously heated to 50° C.-100° C. to make it less viscous. In order to ensure perfect homogeneity of the mixture, the reactor is closed, purged with nitrogen, purged with hydrogen, and then pressurized with hydrogen to a pressure of about 3 MPa. The reactor is then heated to 100° C. At this temperature, stirring is started at 500 rpm. Gradually, the temperature is raised from 100° C. to 200° C. and, in parallel, stirring is gradually increased from 500 to 1000 rpm. At 200° C., the pressure in the reactor is then 4 MPa. A one-hour steady stage at this temperature is observed, so as to ensure proper dissolution and dispersion of the plastic (feedstock fraction II) in the RSV-SR (feedstock I). Following this steady stage, the batch reactor is heated to the reaction temperature, at which point the pressure in the reactor is instantly adjusted to the target value by adding H2. At this point, the reaction time is counted down. At the end of the experiment time, the reactor is rapidly cooled to stop the reaction, stirring is stopped when the reactor is at room temperature, and the liquid effluent and gases are collected for analysis.
Overall Results and Performance:The results relating to the total liquid effluent quality and hydroconversion performance of these two examples are detailed in Table 3 below.
The conversion of the 540° C.+ cut is calculated by the difference in mass between the feedstock and the total liquid effluent, as follows:
There is a slight reduction in yields of C1-C4 cuts by 0.7 points, of light distillates (PI-180° C.) by 3.2 points, of middle distillates (180-350° C.) by 1.9 points, and a significant increase in the yield of vacuum distillates (350-540° C.) by 4.3 points compared with Example 1. The main gain is thus in the production of vacuum distillates, which can be upgraded in other refinery processes. It is also seen that the hydroconversion performance for the test with plastic is substantially identical to that obtained with the reference Example 1 at 430° C. for 300 minutes residence time, indicating conversion of the plastic fraction.
Claims
1. A process for the hydroconversion of a feedstock, comprising:
- (a) conditioning and introducing said feedstock into a first hydroconversion section (20) including at least a first ebullated-bed or hybrid ebullated-entrained hydroconversion reactor comprising a first porous supported hydroconversion catalyst, said feedstock including between 1% and 50% by weight of a plastic fraction and 50% and 99% by weight of a heavy hydrocarbon fraction containing a portion of at least 50% by weight having a boiling point of at least 300° C., and containing sulfur, and nitrogen;
- (b) hydroconverting said feedstock in the presence of hydrogen in said first hydroconversion section (20) to obtain a first hydroconverted effluent (105);
- (c) optionally, separating part or all of said first effluent resulting from (b), to form at least one heavy cut boiling predominantly at a temperature greater than or equal to 350° C.;
- (d) optionally, hydroconverting in a second hydroconversion section including at least a second ebullated bed or hybrid ebullated-entrained bed hydroconversion reactor of part or all of said first effluent resulting from (b) or optionally of said heavy cut resulting from (c), said second hydroconversion reactor comprising a second porous supported catalyst and operating in the presence of hydrogen, to produce a second hydroconverted effluent;
- wherein (b) and optionally (d) are performed at an absolute pressure of between 2 MPa and 38 MPa, at a temperature of between 300° C. and 550° C., at an hourly space velocity relative to the volume of each hydroconversion reactor of between 0.05 h-1 and 10 h-1, and with an amount of hydrogen of between 50 Nm3/m3 and 5000 Nm3/m3, and
- (e) fractionating all or some of said first hydroconverted effluent from (b) or said second hydroconverted effluent from (d), in a fractionation section (30), to produce at least one heavy liquid product (106b) boiling predominantly at a temperature greater than or equal to 350° C., said heavy liquid product containing a residual fraction boiling at a temperature greater than or equal to 540° C.
2. The process as claimed in claim 1, in which, in (a), the plastic fraction and the heavy hydrocarbon fraction of the feedstock (114, 117, 120, 122, 125) are introduced mixed into said at least one first hydroconversion reactor of the first hydroconversion section (20).
3. The process as claimed in claim 2, in which, in (a), the plastic fraction in the form of solid particles (102) is mixed with the heavy hydrocarbon fraction (101) in such a way as to form a suspension (113), said suspension (113) being heated to a temperature above the melting point of said plastic fraction to form the feedstock (114) introduced into the first hydroconversion reactor.
4. The process as claimed in claim 2, in which, in (a), the plastic fraction in the form of solid particles (102) is premixed with a plastic diluent (107) to form a first suspension (115), and said first suspension (115) is then mixed with the heavy hydrocarbon fraction (101) to form a second suspension (116), said second suspension (116) being heated to a temperature above the melting temperature of said plastic fraction to form the feedstock (117) introduced into the first hydroconversion reactor.
5. The process as claimed in claim 2, in which, in (a), the plastic fraction in the form of solid particles (102) is heated to a temperature above the melting point of said plastic fraction to form a molten plastic fraction (118, 121), and said molten plastic fraction (118, 121) is then mixed with the heavy hydrocarbon fraction (101) in such a manner as to form the feedstock (119, 122) introduced into the first hydroconversion reactor.
6. The process as claimed in claim 2, in which, in (a), the plastic fraction in the form of solid particles (102) is heated to a temperature above the melting point of said plastic fraction to form a molten plastic fraction (123), and said molten plastic fraction (123) is then mixed with a plastic diluent (107) to form a dilute molten plastic fraction (124) mixed with the heavy hydrocarbon fraction (101) to form the feedstock (125) introduced into the first hydroconversion reactor.
7. The process as claimed in claim 1, in which, in (a), the plastic fraction (103, 109, 110, 112) and the heavy hydrocarbon fraction (101) of the feedstock are introduced separately into said at least one first hydroconversion reactor of the first hydroconversion section (20).
8. The process as claimed in claim 7, in which, in (a), the plastic feedstock in the form of solid particles (102) is sent into an extruder (10) in which it is gradually heated to a temperature greater than the melting point of said plastic fraction, and placed at the pressure of the first hydroconversion reactor, during a conveying, and said extruded plastic fraction (103) is introduced into the first hydroconversion reactor.
9. The process as claimed in claim 7, in which, in (a), the plastic fraction in the form of solid particles is mixed with a plastic diluent (107) in a mixing section (11) and heated in a heating section (12) to a temperature greater than the melting point of said plastic fraction before its introduction into the first hydroconversion reactor, it being possible for the heating to be performed before or after the mixing with the plastic diluent.
10. The process as claimed in claim 7, in which, in (a), the plastic fraction in the form of solid particles is previously sent to a mixer (13) to be mixed with a plastic diluent (107) and form a suspension (110) and said plastic fraction in the form of a suspension (110) is introduced into the first hydroconversion reactor.
11. The process as claimed in claim 7, in which, in (a), the plastic fraction in the form of solid particles is premixed with a plastic diluent (107) and with the first porous supported hydroconversion catalyst in a distribution and mixing box (14) to form a suspension (112), and said suspension (112) is then introduced into the first hydroconversion reactor via the means for injecting the catalyst into said first hydroconversion reactor.
12. The process as claimed in claim 1, in which the feedstock includes between 5% and 30% by weight of said plastic fraction, and between 70% and 95% by weight of said heavy hydrocarbon fraction.
13. The process as claimed in claim 1, including the separation (c) of separating part, or all, of the first hydroconverted effluent (105) from (b) to produce at least the heavy cut boiling predominantly at a temperature greater than or equal to 350° C., and including (d) the hydroconverting of said heavy cut.
14. The process as claimed in claim 1, in which the hydroconversion reactor(s) of the first hydroconversion section (20) in (b), and optionally in hydroconversion (d), are hybrid ebullated-entrained bed reactors, said process also including introducing a catalyst precursor (104), preferably molybdenum 2-ethylhexanoate, prior to injection of said feedstock into said at least one first ebullated-entrained hybrid bed reactor of the first hydroconversion section (20), in such a way that a colloidal or molecular catalyst, preferably including molybdenum disulfide, is formed when said feedstock reacts with sulfur.
15. The process as claimed in claim 1, in which the first hydroconversion catalyst, and optionally the second hydroconversion catalyst, contains at least one non-noble Group VIII metal chosen from nickel and cobalt, preferably nickel, and at least one Group VIB metal chosen from molybdenum and tungsten, preferably molybdenum, and including an amorphous support, preferably alumina.
16. The process as claimed in claim 2, in which, in (a), the plastic fraction in the form of solid particles (102), premixed with a plastic diluent (107) to form a suspension (120), is heated to a temperature above the melting point of said plastic fraction to form a molten plastic fraction (118, 121), and said molten plastic fraction (118, 121) is then mixed with the heavy hydrocarbon fraction (101) in such a manner as to form the feedstock (119, 122) introduced into the first hydroconversion reactor.
17. The process as claimed in claim 7, in which, in (a), the plastic feedstock in the form of solid particles (102) is sent into an extruder (10), with a plastic diluent (107), in which it is gradually heated to a temperature greater than the melting point of said plastic fraction, and placed at the pressure of the first hydroconversion reactor, during a conveying for a period of time of less than 15 minutes, and said extruded plastic fraction (103) is introduced into the first hydroconversion reactor.
18. The process as claimed in claim 7, in which, in (a), the plastic fraction in the form of solid particles is mixed with a plastic diluent (107) in a mixing section (11) and heated in a heating section (12) to a temperature of between 60° C. and 295° C., before its introduction into the first hydroconversion reactor, it being possible for the heating to be performed before or after the mixing with the plastic diluent and after the mixing with the plastic diluent.
19. The process as claimed in claim 7, in which, in (a), the plastic fraction in the form of solid particles is previously sent to a mixer (13) to be mixed with a plastic diluent (107) and form a suspension (110), at a temperature greater than or equal to room temperature and less than the melting temperature of said plastic fraction, and said plastic fraction in the form of a suspension (110) is introduced into the first hydroconversion reactor.
20. The process as claimed in claim 1, in which the feedstock includes between 5% and 20% by weight of said plastic fraction, and between 80% and 95% by weight of said heavy hydrocarbon fraction.
Type: Application
Filed: Dec 13, 2022
Publication Date: Feb 13, 2025
Applicant: IFP Energies nouvelles (Rueil-Malmaison Cedex)
Inventors: Jean-Patrick BARBÉ (Rueil-Malmaison Cedex), Charles BONNIN (Rueil-Malmaison Cedex), Wilfried WEISS (Rueil-Malmaison Cedex), Joao MARQUES (Rueil-Malmaison Cedex), Duc NGUYEN-HONG (Rueil-Malmaison)
Application Number: 18/721,818
