PROCESS AND APPARATUS FOR PRODUCING METALLURGICAL COKE FROM PETROLEUM COKE OBTAINED IN MINERAL OIL REFINERIES BY COKING IN "NON-RECOVERY" OR "HEAT-RECOVERY" COKING OVENS

Abstract

The invention relates to a process for producing metallurgical coke from petroleum coke generated in crude oil refineries, by coking in “heat-recovery” coking ovens, starting from petroleum coke obtained or generated in crude oil refineries and possessing from the outset a volatiles content of 15 to 19 weight percent and an ash fraction of up to 2 Weight percent, this petroleum coke being introduced in densified form into a coking oven of “non-recovery” or “hat-recovery” construction for the purpose of cyclical coking, said oven being equipped with at least one externally heated burner, so that the primary healing space or the secondary heating space below the coking oven chamber, or both, are heated to a temperature of between 1000° C. to 1550° C., and within a time period of less than 120 h, the volatiles fraction present in the petroleum coke is completely outgassed, giving a metallurgical coke having a CSR strength of at least 44% and a CRI reactivity of less than 33%, being suitable for use as iron- and steelmaking coke The invention also relates to a coking oven which is constructed according to the “non-recovery” or “heat-recovery” coking ovens principle and which comprises a primary heating space, and which is equipped with burners which heat the primary heating space.

Description

The invention relates to a process for producing metallurgical coke from petroleum coke generated in crude oil refineries, by coking in “non-recovery” or “heat-recovery” coking ovens, starting from petroleum coke obtained or generated in crude oil refineries and possessing from the outset a volatiles content of 15 to 19 weight percent and an ash fraction of up to 2 weight percent, this petroleum coke being introduced in densified form into a coking oven of “non-recovery” or “heat-recovery” construction for the purpose of cyclical coking, said oven being equipped with at least one externally heated burner, so that the primary heating space or the secondary heating space below the coking oven chamber, or both, are heated to a temperature of between 1000° C. to 1550° C., and within a time period of less than 120 h, the volatiles fraction present in the petroleum coke is completely outgassed, giving a metallurgical coke having a CSR strength of at least 44% and a CRI reactivity of less than 33%, being suitable for use as metallurgical coke. The invention also relates to a coking oven which is constructed according to the “non-recovery” or “heat-recovery” coking ovens principle and which comprises a primary heating space which is equipped with burners which heat the primary heating space.

The products of the processing of mineral oil and crude oil in refineries to form crude oil products include not only the desired products but also one known as petroleum coke, which is formed from high-boiling residues in distillation operations, reforming steps, hydrogenation processes, and purifying operations in a crude oil refinery. This petroleum coke consists typically of more than 88 weight percent carbon, with a volatile constituents (VOC) content of 8 to 12 weight percent. This petroleum coke is only of minor economic interest, possessing properties which are unwanted in relation to numerous value-raising operations, such as a low CSR strength and a high CRI reactivity, for example, and for that reason finding no suitable consumer markets.

Petroleum coke is used frequently in niche applications such as, for example, metallurgy for producing electrodes. The use of petroleum coke in iron and steel technology, i.e., for example, as a reducing agent in a blast furnace operation for producing pig iron, is not possible, since the strength of the petroleum coke is insufficient for use in a blast furnace, Additionally) known is the admixing of fractions of petroleum coke to bituminous coal mixtures, but the admixed fraction of the petroleum coke is limited to orders of magnitude of less than 10 weight percent, owing to the low quality of the blast furnace coke produced from it.

A further problem with petroleum coke are impurities which come from the processing of the crude oil, and which have accumulated in the petroleum coke in the course of its removal.

Impurities frequently encountered in the petroleum coke are, for example, vanadium, nickel, sulfur, silicon, iron, or titanium. For instance the vanadium content of petroleum coke fractions can be up to 0.17 wt %, the nickel content up to 0.04 wt %, and the sulfur content up to 5 wt %. A consequence of these impurities is that the petroleum coke also cannot be used directly for heating purposes, since to do so would pollute the environment. Another characteristic of petroleum coke is that of having a lower flame temperature than blast furnace coke or coal. hi relation to its use :as a fuel, and its handling, this is an undesirable feature, ruling out the possibility of using it for numerous further-processing Operations. Possibilities are therefore sought fur providing an economic possibility for use of petroleum coke.

A substantial barrier to obtaining metallurgical coke by adapting the coking process in line with the properties of the petcoke, besides the impurities and the lack of strength of the product, lies, in turn, in a fluctuating proportion of volatile constituents. The consequence of the fluctuating proportion of volatile constituents is that the use in a coking oven is difficult to control, owing to the substantially incalculable heating properties arising from the volatile constituents. Generally speaking, the main fraction of the petroleum coke generated in refineries has a very low fraction of volatile constituents, of less than 19 weight percent, with the consequence that, if used in a “non-recovery” or “heat-recovery” coking oven, the coke is unsuitable for maintaining a self-supporting combustion—and hence coking—process. Given exclusive use of petcoke as the starting material in this coking oven, the coking operation would then conic virtually to standstill after a number of coking cycles, since the heat generated by combustion of the volatile constituents during coking, and stored in the refractory material of the oven, is no longer sufficient to keep the oven temperature at the required high figure of more than 1000° C. during the subsequent batches.

A further difficulty affecting its coking is that petcoke exhibits very high swelling pressures in the course of the coking procedure, attributable to the presence therein of low-boiling volatile constituents. These constituents lead during the coking procedure to a substantial increase in the volume of the cake of coke, amounting virtually to an inflation. It is therefore not possible to coke petroleum coke in a conventional coking oven, since the walls of a coking oven chamber would be damaged in the course of the coking procedure, as a result of the increase in volume of the petroleum coke cake. The increase in volume of the petroleum coke cake, arising from the stated properties of the petroleum coke cake, has the consequence, moreover, that the coke product generated using petcoke fractions in the bituminous coal mixture is very difficult to force out from a conventional coking oven chamber.

One possibility for the workup and further use of petcoke is given by WO0010914 A1. The teaching provides a process for subjecting petcoke from crude oil refineries, which is obtained from a petcoke precursor material from mineral oil, to a thermal cracking operation, at sufficiently high temperature, and for a sufficiently long time period at a sufficient pressure, to furnish a petcoke which contains a diminished and precision-adjustable volatiles content of 13 to 50 weight percent. The process, moreover, discloses a possibility for desalting the petcoke, to remove the metallic impurities it contains. Lastly, the teaching also discloses a possibility for taking back the sulfur impurities in the petcoke to a lowered and environmentally acceptable fraction, by means, for example, of adding desulfurizing agents to a fluidized bed. The process provides an opportunity to provide petcoke fractions having a. very precision-determinable content of volatile constituents and of impurities. Petcoke fractions having a volatiles fraction of 15 to 25 weight percent are referred to here as petroleum coke but have also been dubbed “petroleum coal”, since their properties resemble those of conventional bituminous fat or forge coals.

The availability of petroleum coke with a precision-determinable fraction of volatile constituents and of impurities is opening up new opportunities for utilizing the resulting petroleum coke for the production of metallurgical coke. Crude oil processing generates a particularly high fraction of petroleum coke having a volatile constituent of 15 to 19 weight percent. This product has to date not been processed further on an industrial scale, since the conventional coking processes do not allow a solution to the problems associated with this product: low energy content, low economics, dangerous swelling pressure during coking, substantial contamination, and high firing losses. Laboratory studies of the metallurgical coke produced from this specific petcoke fraction, however, attest to its high quality. Examples of these studies are taught in the article by Stukov et al., “Increasing the Strength of Metallurgical Petroleum Coke to the Coking Batch”, Coke and Chemistry. 2009, Vol. 52, No. 8, pp. 349-352. Since technical feasibility has so far not been ensured in the production of metallurgical coke from petroleum coke, a need exists to obtain a feasible process for producing metallurgical coke through coking of petroleum coke in a coking oven.

The object, therefore, is to provide a process which affords petroleum coke with a fraction of 15 to 19 weight percent of volatile constituents and of an increased fraction of impurities, utilizes it for coking on an industrial scale, and provides therefrom a coke which possesses an increased strength and a low reactivity, and which is suitable for use as metallurgical coke.

The present invention achieves this object by means of a process which presents petroleum coke having a known volatile constituents content of 15 to 19 weight percent and a known ash fraction of up to 2 weight percent, and then carries out coking of this petroleum coke, in densified form, under regular conditions, with temperatures in the heating chambers between 1000° C. to 1550° C., within a time period of 120 hours, in a “non-recovery” or “heat-recovery” coking oven, to give metallurgical coke, the oven being equipped with at least one burner for heating the primary heating space, formed by the has space present in operation above the petroleum coke cake, or for heating the secondary heating space, below the coking oven chamber, or both.

The volatiles content and the ash content of the petcoke are determined by analysis prior to coking, it being immaterial whether the analysis is carried out on the coking oven plant site or on the site of the petroleum coke supplier. All that is important for performance of the process of the invention is that a petroleum coke is presented that has a known volatile constituents content, the range to be complied with being at least 15 weight percent and not more than 19 weight percent.

In order to compensate for the reduced energy content, arising from the lower fraction of volatile constituents, in the petroleum coke having the slated properties, it is necessary to use an external heating gas to heat the primary heating space or the secondary heating space, since the desire is to subject only this low-energy petroleum coke fraction to further processing to give metallurgical coke in a non-recovery or heat-recovery coking reactor. The consequence otherwise would he a disproportionately long and uneconomic coking time, since the low energy content of the feedstock. is not enough to keep the temperatures consistently at the requisite level at more than 1000° C. and so to compensate the high offgas losses and radiant losses associated with the operation.

Through the use of a coking oven of non-recovery or heat-recovery construction it is nevertheless possible to coke a charge mixture consisting primarily of petroleum coke and possessing the stated characteristics, since a construction of this kind for the coking oven leaves a gas space free above the petroleum coke cake in the operating state, this gas space capturing the high swelling pressures produced by petroleum coke. In the context of the invention it has been ascertained that the coke grades thus obtained have strengths of more than 44% CSR and reactivities of less than 33% CRI, thereby allowing them to be employed for use as metallurgical coke, in iron and steel operations or blast furnace operations, for example. The stated figures for a coke are beneficial for a blast furnace operation if this coke is used in a blast furnace operation.

Claimed in particular is a process for producing metallurgical coke from petroleum coke obtained in the crude oil processing industry, where

• • petcoke from petrochemical processes is subjected to analysis of the volatiles content and the ash content, so that it can be sorted into batches with a known content of volatile constituents and ash content, and
  • a petroleum coke batch with a volatiles content of 15 to 19 weight percent and an ash fraction of less than 2 weight percent, based on the water-free and ash-free petroleum coke batch, is obtained by sorting, and is placed into a coke reservoir bunker or coke storage container, and
  • this petroleum coke fraction from the coke reservoir bunker or coke storage container is placed by filling machines first into a compacting means for densification and then into a coking oven with the dimensions of the “non-recovery” or “heat-recovery” design for cyclical coking,
    and which is characterized in that
  • the coking oven is equipped with at least one externally heated burner for heating the primary heating space above the petroleum coke cake or for heating the secondary heating space below the coking oven chamber, or both, by which the petroleum coke in the coking oven chamber is heated with a hot heating gas to a temperature of 1000° C. to 1550° C. within a time period of less than 120 h, to give a metallurgical coke having a CSR strength of at least 44% and a CRI reactivity of less than 33%.

Coking ovens of the non-recovery or heat-recovery type with primary and secondary heating spaces are known to the person skilled in the art of coking technology. This type of construction is described comprehensively by way of example in the article by Walter Buss et al., “Thyssen Still Otto/PACTI Non-recovery coke making system”. Iron and Steel Engineer, Association of Iron and Steel Engineers, Pittsburgh, USA, Volume 76, No. 1. January 1999, pages 33-38. A coking oven battery of coking ovens suitable for the coking of carbonaceous feedstocks with high swelling pressures is exemplified by WO2011107198A1. In the course of the heating procedure, the cake of petroleum coke reaches an estimated temperature of 900 to 1100° C.

As a result of the heating taking place above the densified cake of petroleum coke, the petroleum coke is heated in such a way as to produce a coke of the desired quality, with the fraction of volatile constituents in the petroleum coke ascending from the batch in the form of crude coking gas. Part of these outgassed constituents is combusted substoichiometrically for heat generation at least occasionally in the primary heating space, initially with addition of air. The partly combusted offgas mixture is then taken off via the lateral gas channels of the coking oven chamber, and combusted completely by further combustion in the secondary heating space. As a result of the volatiles fraction present in the petroleum coke, therefore, the petroleum coke is heated from below as well with the consequence that. with the exception of the side door regions, the cake of petroleum coke is heated from all sides and a uniform quality of coking is obtained.

The quality of the coke obtained can he determined as described, giving CSR strengths of at least 44% and a CRI reactivity of less than 33%. The prerequisite is the use of a petroleum coke batch which possesses a volatiles content of 15 to 19 weight percent and an ash fraction of less than 2 weight percent, based on the water-free and ash-free petroleum coke batch.

Also possible is the use of a petroleum coke whose volatile constituents content is determined with greater precision. In one embodiment of the invention, the volatiles content of the petroleum coke is 16 to 18 weight percent. As a result, the operation can be controlled more effectively.

In order to implement the invention, the petroleum coke cake can in principle be heated from all sides, thereby attaining the desired temperature. In one advantageous embodiment of the invention, the heating is performed in the coking oven such that the burner flame is introduced horizontally into the gas space over the petroleum coke batch, referred to as the primary heating space. For this purpose, in one advantageous embodiment, at least one burner pipe is situated in the wall above the coking oven chamber door, this pipe being fed with a hot gas or combustion gas by a burner and opening out through an opening in the gas space above the petroleum coke, thereby heating this space with hot gas. The horizontal arrangement of the burner pipes above the batch ensures that the inflowing gas flows into the primary heating chamber above the petroleum coke cake and, as a result, direct contact between the coke surface and the combustion air, and hence unwanted burnoff of feed coke or product coke, is lessened. At the same time, a vertical distance of more than 100 mm is established between the burner pipe introduced and the top edge of the batch, so that the top layers of petroleum coke are not combusted.

In the context of the invention it is also possible, for example, to heat the petroleum coke by means of further burners, arranged in the secondary heating space below the petroleum coke. In a further embodiment, the sole or simultaneous arrangement of at least one burner at the lateral end-fare openings of the secondary heating space is claimed, thereby raising the temperature of this heating space as well and so intensifying the heating of the batch from below. It is also possible, lastly, to utilize the ceiling openings in the coking oven chamber for heating. A wall-heated construction of a coking oven, as disclosed in U.S. Pat. No. 4,045,299, for example, is also conceivable for implementation, although it has not been tried out for the present invention,

The heating may be adjusted with the aeration and pressure regulation of the coking oven chamber, for example, in such a way an overpressure of 0.01 to 20 mbar is established in the coking oven chamber. This can be achieved by corresponding regulation of the burner and of the aeration shutters. In one preferred embodiment of the invention, the heating is adjusted with the aeration and pressure regulation in such a way that an overpressure of 0.1 to 10 mbar is established in the coking oven chamber.

The coking oven chamber can be heated using natural gas as heating gas, for example. To heat the coking oven chamber it is also possible, however, to use liquid gas, coking oven gas, blast furnace top gas, or converter gas as heating gas. To implement the process of the invention it is also possible to use a mixture of at least two gases from the gases group—natural gas, liquid gas, coking oven gas, blast furnace top gas, or converter gas—in any proportion for the heating. The choice of an appropriate heating gas is dependent on a variety of factors, such as on availability, for example.

Setting the content of volatile constituents in the petroleum coke introduced is important in order to achieve the desired CSR strength and CRI reactivity of the coke product, and in order to ensure a desired heatability with the heating performance through the outgassing constituents. In one embodiment of the invention, prior to grinding, the petroleum coke mixture is mixed with bituminous coal as adjuvant, so that the volatiles content is between 19 and 25 weight percent, based on the dry charge mixture. In a further embodiment, prior to grinding, the petroleum coke mixture is mixed with bitumen as adjuvant, so that the volatiles content is between 19 and 25 weight percent, based on the dry charge mixture. In a further embodiment, prior to grinding, the petroleum coke mixture is mixed with an oil grade as adjuvant, so that the volatiles content is between 19 and 25 weight percent, based on the dry charge mixture. The coke product obtained as a consequence possesses a CSR strength of more than 44% and a CRI reactivity of less than 33%.

As a result of the process steps in which it is obtained, moreover, the petroleum coke employed possesses an ash fraction which is below 2 weight percent, In general this is just enough to protect the petroleum coke from excessive burnoff by combustion in the course of coking. In order to ensure sufficient economics of the process. however, it is frequently necessary to take additional measures against unwanted burnoff of the petcoke. For this purpose it is also possible to select a somewhat higher volatile constituents content if the petroleum coke is admixed with adjuvants which possess an inhibiting effect on the combustion of the petroleum coke.

The ash fraction as well may be selected at a higher level if the petroleum coke is admixed with an adjuvant which exerts an influence on the turnoff behavior of the petroleum coke. The function of the ash fraction is to prevent unwanted combustion of the petroleum coke. in one embodiment of the invention, the petroleum coke mixture is admixed with ash as adjuvant, so that the ash fraction is set at between 2 and 12 weight percent, preferably 2 to 6 weight percent, based on the dry total mixture, and this mixture is ground and classified, giving a fraction having a particle size distribution d of 0.5<d<3 mm, and the classified mixture for further coking is placed into the coke reservoir bunker or coke storage container. Grinding and classifying are necessary to ensure that the ash is distributed within the product in such a way as not to deleteriously alter the CSR strength and CRI reactivity attained.

In a further embodiment, the petroleum coke mixture is admixed with ash-containing coal as adjuvant, so that the ash fraction is set at between 2 and 12 weight percent. preferably 2 to 6 weight percent, based on the dry total mixture, and this mixture is ground and classified, giving a fraction having a particle size distribution d of 0.5<d<3 min, and the classified mixture for further coking is placed into the coke reservoir bunker or coke storage container. The petroleum coke mixture as well before the admixing of the adjuvants or after the admixing of the adjuvants, can be wholly or partly ground in a grinding device, to give an average particle size for the residue fraction of less than 3 mm. The grinding operation may also be carried out for a partial fraction of the total mixture. Preferred partial fractions in that case are from 70 to 95 weight fraction and more preferably from 80 to 90 weight fraction.

In the context of the invention it is also possible to modify the water content of the petroleum coke employed by addition of water. The addition of water may improve the stability of the petroleum coke cake. In one embodiment of the invention, the total water content of the charge mixture is adjusted by addition of liquid water to 7 to 11.5 weight percent, and this mixture for further coking is placed into the coke reservoir bunker or coke storage container. The water may be added directly, or alternatively by spraying or immersing.

In the context of the invention, the charge mixture, prior to charging, can be compacted with a densifying device of whatever kind, so that the density of the charge mixture is 0.8 t/m³ to 1.225 t/m³. The densifying operation may take place in general by steps of press, ram, hammering or vibrating processes, which may also be performed in combination. Preferably, prior to charging, the charge mixture is compacted with a ram device such that the density of the charge mixture is 1.0 t/m³ to 1.150 t/m³.

In order to influence the coking operation, it is possible, before the heating is commenced, to apply a combustion-inert parting layer to the surface a the oven load. This layer consists exemplarily of coke. In a further embodiment, this combustion-inert parting layer consists of coal. Lastly, this combustion-inert parting layer may also consist of ash or sand. Finally, this combustion-inert parting layer may consist of carbon-containing lumps in the form, for example, of lump coal or lump coke having a grain size of less than 25 mm.

In one embodiment of the invention, the thickness of the parting layer is 0.2 cm to 25 cm. The parting layer can be applied in any way. Thus, for example, it is possible to apply the parting layer to the compacted coke with a coke compacting machine which includes an addition opening arranged on or between the rams. This requires a coke compacting means which comprises at least one ram with an addition means above the batch. Coke compacting machines which are provided with rams or with hammering, vibrating, and pressing devices for compacting are pan of the prior art and are described by way of example in WO2010102714A2.

In a further embodiment, the adjuvant is stored in the coke reservoir bunker in a special shaft from which, during loading of the compacts, the adjuvant is introduced into the opening intended for that purpose in the coke compacting machine. The adjuvant may be added into the opening intended for that purpose in the coke compacting machine by means of a screw conveyor. The adjuvant may therefore also be added into the opening intended for that purpose in the coke compacting machine by means of a slider system, a chain conveying system, a free-fall means or a slide means. The parting layer may also be tipped onto the surface of the hatch subsequently, outside the compacting means.

In a further embodiment of the invention, the charge mixture is mixed with the adjuvants in four successive mixing bunkers, in which grinding and mixing of the ground material takes place. The grinding and mixing may also take place in a plurality of stages. The charge mixture may also be preheated. Thus, for example, it is possible to adjust the temperature of the charge mixture, before it is filled into the coking oven, to 120 to 250° C. by preheating in a heatable container.

The metallurgical coke obtained from the petroleum coke may be put to any further use In particular it may be employed as blast furnace coke. Alternatively, it can he used in nonferrous metallurgy for producing metals or for producing electrodes.

Also claimed is an apparatus with which the process of the invention can be implemented. Claimed more particularly is a coking oven for coke generation from petroleum coke obtained in the crude oil processing industry, which oven

• • is constructed on the principle of a “non-recovery” or “heat recovery” coking oven battery, which possesses a coking oven chamber width of 2 to 6 meters and a coking oven chamber length of 10 to 20 m, so that, for a height of 2 m, the volume of the coking oven chamber is 40 to 240 m³, and
  • the coking oven possesses a brick-lined roof apex, which is able, with the underlying coking oven chamber, to form a gas space which is present over the coke cake in the filled state, as primary heating space, and
  • the coking oven is equipped with lateral off-gas channels and a secondary heating space situated under the coke, and
  • the coking oven chamber is furnished with a coke reservoir bunker or coke storage container and with a filling machine which is able to fill the coking oven chamber from the coke reservoir hunker or coke storage container,
    and which is characterized in that
  • the coking oven chamber is heated with external burners which heat the primary heating space, and the burners are supplied with a heating gas and an oxygen-containing gas via collecting mains along the coking oven chamber front and regulatable branch lines into the burners.

The external burners can be arranged arbitrarily on the coking oven chamber in order to permit heating of the primary heating space. They may be arranged individually or plurally per coking oven chamber. In one preferred embodiment, however, the burner or burners are located on at least one side of the coking oven chamber, in the wall comprising the coking oven chamber door, over the coking oven chamber door, and heat the primary heating space through an opening located in the wall comprising the coking oven chamber door. Through this opening, the mouthpiece segment of the burner pipe is guided into the gas space.

For this purpose, the burner or burners are located on at least one side of the coking oven chamber, in the wall comprising the coking oven chamber door, over the coking oven chamber door, and heat the primary heating space through an opening located in the wall comprising the coking oven chamber door, and in one advantageous embodiment a vertical distance of more than 100 mm is established between the burner pipe outlet and the top edge of the petroleum coke batch, Arranging the burners on the ceiling of the coking oven chamber, in turn, is space-saving.

In one embodiment of the invention, the burner pipe outlet or burner pipe outlets are made from a heat-resistant steel. In another embodiment, the burner pipe outlet or burner pipe outlets are made from a refractory ceramic material. This may he present on one burner or on a plurality of burners, if a plurality of burners is installed.

In one preferred embodiment of the invention, the coking oven of the invention is associated with a further plurality of coking ovens to form a coking oven battery, and the collecting main extends along the coking oven chamber front of the coking oven battery. The aggregation of coking ovens of the non-recovery or heat-recovery type into coking oven batteries is something familiar to the person skilled in the art of coking plant technology.

The secondary heating space as well may be heated with one or more external burners, which are supplied with a heating gas and an oxygen-containing gas via a collecting main along the coking oven chamber front, with regulatable branch lines opening out into _the burners. In one embodiment of the invention, the burner or burners are in the form of blower burners. For implementation, the collecting main may be located by way of example on the coking oven chamber ceiling. The collecting main may also be located in mounted form below the platform for the coking oven service machine or along the anchor stands. Lastly, the collecting main may be arranged arbitrarily, in order to ensure the supply to the burner or burners.

The branch line or branch lines may be regulated, by way of example, via a tap, a slider, a nozzle, a flap, or a shutter. In one embodiment of the invention, the coking oven battery comprises a pressure regulating station in which the heating gas is constricted to the required pressure, and so is passed from the pressure regulating station via the collecting main into the burners, and is provided directly for the burners with the correct pressure.

Also claimed is a compacting means for compacting coal, which is suitable for applying a parting layer to coke compacts during the production of compacts. A suitable compacting means which can be utilized for producing this device is described by the teaching of WO2010102714A2. Said means consists of six rams, which are used as side faces during the formation of compacts by a pressing device. In one embodiment of the invention, the rams are operated hydraulically. A suitable compacting means may also be formed from a vibrating device. To form the compacting means of the invention, the upper ram or the upper plate of the vibrating device of the compacting means from WO2010102714A2 is provided with a dumping means by which an adjuvant can be placed onto the surface of the compact, so that, on compacting, a further layer of an adjuvant added by the dumping means is formed on the surface of the compacted charge mixture.

Also claimed is a coking oven battery which is composed of the coking ovens of the invention, and which is equipped with this compacting means.

The Process of the invention is employed primarily in coking oven batteries which are formed from the coking oven chambers of the invention with ancillary means from the prior art. These include, for example, 1 to 10 type bunkers, in which the different petroleum coke charge mixtures are stored. Also included, for example, are 1 to 4 grinding devices, 1 to 4 screening devices, or 1 to 4 mixing bunkers, in which the petroleum coke, the adjuvants, or the total charge mixture is or are stored, classified, or mixed. The coking oven batteries may also have been provided with a compacting means.

The invention possesses the advantage of providing an economic means of use for a petroleum coke obtained in crude oil refineries and in the mineral oil processing industry, and representing a petcoke fraction having a volatiles content of 15 to 19 weight percent. by producing therefrom a coke which possesses a CSR strength of more than 44% and a CRI reactivity of less than 33%, thereby allowing it, unlike coked petcoke, to be used in a blast furnace operation or in smelting operations for producing metals.

EXAMPLES

Described below are analytical methods for petcoke, serving to provide a petroleum coke which functions as a starting petroleum coke for the process of the invention,

1. Volatiles content. The volatiles content of the petcoke is determined by way of example in accordance with DIN 51720. The quantity measured is the fraction of the residue which remains after heating of the coke under reduced pressure to 900° C. within 7 minutes. A method for rapid determination of the volatiles content of coke is given by U.S. Pat. No. 6,074,205.

2. Ash content. The ash content is determined by way of example in accordance with DIN 51719. The quantity measured is the fraction of the residue which remains after combustion of the coke in an oven at 815° C. A method for rapid determination of the ash content in coke is given by DE3120064A1.

3. Coke strength. The strength of coke is determined by the test known as the CSR test. CSR here stands for “Coke Strength after Reaction”. The quantity measured is the percentage eight of the residue obtained from a 200 g test block of coke after heating under 1 bar of carbon dioxide (CO₂) at 1100° C. for 2 hours with subsequent treatment in a rotary drum at 600 revolutions per minute (min⁻¹) for 30 minutes. This test method is nowadays generally recognized, has been standardized, and is described by way of example in EP0738780B2.

4. Coke reactivity. The reactivity of coke is determined by the test known as the CRI test. CRI here stands for “Coke Reactivity Index” and describes the chemical reactivity of the coke. The quantity measured is the percentage weight of the residue obtained from a 200 g test block of coke after heating under 1 bar of carbon dioxide (CO₂) at 1100° C. for 2 hours. The resulting value is called the CRI reactivity. The smaller the value obtained, the lower the reactivity. This method is simple and quick to carry out, and the characteristic CRI value permits good correlation with the behavior of the coke in a blast furnace operation. This test method is nowadays generally recognized, has been standardized by ISO 18894, and is described by way of example in EP1142978A1.

Claims

1. A process for producing metallurgical coke from petroleum coke obtained in the crude oil processing industry, where characterized in that

petcoke from petrochemical processes is subjected to analysis of the volatiles content and the ash content, so that it can be sorted into hatches with a known content of volatile constituents and ash content, and

a petroleum coke batch with a volatiles content of 15 to 19 weight percent and an ash fraction of less than 2 weight percent, based on the water-free and ash-free petroleum coke batch, is obtained by sorting, and is placed into a coke reservoir bunker or coke storage container, and

this petroleum coke fraction from the coke reservoir bunker or coke storage container is placed by filling machines first into a compacting means for densification and then into a coking oven with the dimensions of the “non-recovery” or “heat-recovery” design for cyclical coking,

the coking oven is equipped with at least one externally heated burner for heating the primary heating space above the petroleum coke cake or tot heating the secondary heating space below the coking oven chamber, or both, by which the petroleum coke in the coking oven chamber is heated with a heating gas to a temperature of 1000° C. to 1550° C. within a time period of less than 120 h, to give a metallurgical coke having a CSR strength of at least 44% and a CRI reactivity of less than 33%.

2. The process as claimed in claim 1, characterized in that the volatiles content of the petroleum coke prior to coking is 16 to 18 weight percent.

3. The process as claimed in either of claims 1 and 2, characterized in that the heating is performed in the coking oven, by the burner flame being introduced into the gas space over the petroleum coke batch.

4. The process as claimed in any of claims 1 to 3, characterized in that the coking oven is equipped with at least one externally heated burner for heating the secondary heating space below the petroleum coke cake, by which the petroleum coke cake is heated.

5. The process as claimed in claim 4, characterized in that the heating is performed in the coking oven by the burner flame being introduced into the gas space below the petroleum coke batch.

6. The process as claimed in any of claims 1 to 5, characterized in that the heating is adjusted with the aeration and pressure regulation in such a way that an overpressure of 0.01 to 20 mbar is established in the coking oven chamber.

7. The process as claimed in any of claims 1 to 5, characterized in that the heating is adjusted with the aeration and pressure regulation in such a way that an overpressure of 0.1 to 10 mbar is established in the coking Oven chamber.

8. The process as claimed in any of claims 1 to 7, characterized in that natural gas is used as heating gas for the heating.

9. The process as claimed in any of claims 1 to 7, characterized in that liquid gas is used as heating gas for the heating.

10. The process as claimed in any of claims 1 to 7, characterized in that coking oven gas is used as heating gas for the heating.

11. The process as claimed in any of claims 1 to 7, characterized in that blast furnace top gas is used as heating gas for the heating,

12. The process as claimed in any of claims 1 to 7, characterized in that converter gas is used as heating gas for the heating.

13. The process as claimed in any of claims 8 to 12, characterized in that a mixture of at least two gases from the gases group—natural gas, liquid gas, coking oven gas, blast furnace top gas, or converter gas—in any proportion is used for the heating.

14. The process as claimed in any of claims 1 to 13, characterized in that prior to grinding, the petroleum coke mixture is mixed with bituminous coal as adjuvant, so that the volatiles content is between 19 and 25 weight percent, based on the dry charge mixture.

15. The process as claimed in any of claims 1 to 13, characterized in that prior to grinding, the petroleum coke mixture is mixed with bitumen as adjuvant, so that the volatiles content is between 19 and 25 weight percent, based on the dry charge mixture.

16. The process as claimed in any of claims 1 to 13, characterized in that prior to grinding, the petroleum coke mixture is mixed with an oil grade as adjuvant, so that the volatiles content is between 19 and 25 weight percent, based on the dry charge mixture.

17. The process as claimed in any of claims 1 to 16, characterized in that the petroleum coke mixture is admixed with ash as adjuvant, so that the ash fraction is set at between 2 and 12 weight percent, based on the dry total mixture, and this mixture, prior to coking, is ground and classified, giving a fraction haying a particle size distribution d of 0.5<d<3 mm, and the classified mixture for further coking is placed into the coke reservoir bunker or coke storage container.

18. The process as claimed in any of claims I to 16. characterized in that the petroleum coke mixture is admixed with ash-containing coal as adjuvant, so that the ash fraction is set at between 2 and 12 weight percent, based on the dry total mixture, and this mixture, prior to coking, is ground and classified, giving a fraction baying a particle size distribution d of 0.5<d<3 mm, and the classified mixture for further coking is placed into the coke reservoir bunker or coke storage container.

19. The process as claimed in claim 18, characterized in that the petroleum coke mixture is admixed with ash-containing coal as adjuvant, so that the ash fraction is set at between 2 and 6 weight percent, based on the dry total mixture, and this mixture, prior to coking, is ground and classified, giving a fraction having a particle size distribution d of 0.5<d<3 mm, and the classified mixture for further coking is placed into the coke reservoir bunker or coke storage container.

20. The process as claimed in any of claims 14 to 19, characterized in that the petroleum coke mixture as well, before or after the admixing of the adjuvants, is wholly or partly ground in a grinding device, to give an average particle size of the residue fraction of less than 3 mm.

21. The process as claimed in any of claims 1 to 20, characterized in that the total water content of the charge mixture is adjusted by addition of liquid water to 7 to 11.5 weight percent, and this mixture for thither coking is placed into the coke reservoir hunker or coke storage container.

22. The process as claimed in any of claims 1 to 21, characterized in that the charge mixture, prior to charging, is compacted with a densifying device, so that the density of the charge mixture is 0.8 t/m3 to 1.225 t/m3.

23. The process as claimed in any of claims 1 to 21, characterized in that the charge mixture, prior to charging, is compacted with a ram device, so that the density of the charge mixture is 1.0 t/m3 to 1.150 t/m3.

24. The process as claimed in any of claims 1 to 23, characterized in that before the heating is commenced, a combustion-inert parting layer is applied to the surface of the oven load.

25. The process as claimed in claim 24, characterized in that this combustion-inert parting layer consists of coke.

26. The process as claimed in claim 24, characterized in that this combustion-inert parting layer consists of coal.

27. The process as claimed in claim 24, characterized in that this combustion-inert parting layer consists of carbon-containing lumps having a grain size of less than 25 mm.

28. The process as claimed in claim 24, characterized in that this combustion-inert parting layer consists of ash or sand.

29. The process as claimed in any of claims 24 to 28, characterized h that the thickness of the parting layer is 0.2 cm to 25 cm.

30. The process as claimed in any of claims 24 to 29, characterized in that the parting layer is applied to the compacted coke with a coke compacting machine which includes an addition opening intended for that purpose on the upper die or upper plate.

31. The process as claimed in any of claims 24 to 30, characterized in that the adjuvant is stored in the coke reservoir bunker in a special shaft from which, during loading, the adjuvant is placed into the opening intended for that purpose in the coke compacting machine.

32. The process as claimed in claim 31, characterized in that the adjuvant is added into the opening intended for that purpose in the coke compacting machine by means of a screw conveyor.

33. The process as claimed in claim 31, characterized in that the adjuvant is added into the opening intended for that purpose in the coke compacting machine by means of a slider system.

34. The process as claimed in claim 31, characterized in that the adjuvant is added into the opening intended for that purpose in the coke compacting machine by means of a chain conveying system.

35. The process as claimed in any of claims 24 to 34, characterized in that the charge mixture is mixed with the adjuvants in up to four successive mixing hunkers, in which multistage grinding and mixing of the ground material takes place.

36. The process as claimed in any of claims 1 to 35, characterized in that the temperature of the charge mixture, before it is filled into the coking oven, is preheated to 120° C. to 250° C. in a heatable container.

37. A coking oven for coke generation from petroleum coke obtained in the crude oil processing industry, which oven characterized in that

is constructed on the principle of a “heat-recovery” coking oven battery, which possesses a coking oven chamber width of 2 to 6 meters and a coking oven chamber length of 10 to 20 m, so that, for a height of 2 m, the volume of the coking oven chamber is 40 to 240 m3, and

the coking oven possesses a brick-lined roof apex, which is able, with the underlying coking oven chamber, to form a gas space which is present over the coke cake in the filled state, as primary heating space, and

the coking oven is equipped with lateral off-gas channels and an underlying secondary heating space, and

the coking oven chamber is furnished with a coke reservoir bunker or coke storage container and a filling machine which is able to fill the coking oven chamber from the coke reservoir hunker or coke storage container,

the coking oven chamber is heated with external burners which heat the primary heating space, and the burners are supplied with a heating gas and an oxygen containing gas via collecting mains along the coking oven chamber front and regulatable branch lines into the burners.

38. The coking oven as claimed in claim 37, characterized in that the burner or burners are located on at least one side of the coking oven chamber, in the wall comprising the coking oven chamber door, over the coking oven chamber door, and heat the primary heating space through an opening located in the wall comprising the coking oven chamber door, with a vertical distance of more than 100 mm being established between the burner pipe outlet and the top edge of the batch.

39. The coking oven as claimed in either of claims 37 and 38, characterized in that the burner pipe outlet is made from a heat-resistant steel.

40. The coking oven as claimed in either of claims 37 and 38, characterized in that the burner pipe outlet is made from a refractory ceramic material.

41. The coking oven as claimed in any of claims 37 to 40, characterized in that the coking oven is associated with a further plurality of coking ovens to form a coking oven battery, and the collecting main extends along the coking oven chamber front of the coking oven battery.

42. The coking oven as claimed in any of claims 37 to 41, characterized in that the secondary beating space as well is heated with an external burner, which is supplied with a heating gas and an oxygen-containing gas via a collecting main along the coking oven chamber front, said main opening out into the burner via a regulatable branch line.

43. The coking oven as claimed in any of claims 37 to 42, characterized in that the burner or burners are in the form of blower burners.

44. The coking oven as claimed in any of claims 37 to 43, characterized in that the collecting main is located on the coking oven chamber ceiling.

45. The coking oven as claimed in any of claims 37 to 44, characterized in that the collecting main is located below the platform for the coking oven service machine.

46. The coking oven as claimed in any of claims 37 to 45, characterized in that the branch line or branch lines is or are regulated is as tap, a slider, a flap, as nozzle or a shutter.

47. The coking oven as claimed in any of claims 37 to 45, characterized in that the coking oven battery comprises a pressure regulating station in which the heating gas is restricted to the required pressure, and is passed thus from the pressure regulating station via the collecting main into the burners.

48. A compacting means for compacting coal, which consists of up to eight rams, the rams being used to form compacts by means of a densifying device, characterized in that the compacting means comprises a dumping means by which an adjuvant can he placed onto the surface of the compact, so that on compacting, a further layer of an adjuvant added by the dumping means is formed on the surface of the compacted charge mixture.

49. The compacting means for compacting coal as claimed in claim 48, characterized in that the compacting means comprises a hydraulic pressing device fur the formation of compacts.

50. The compacting means for compacting, coal as claimed in claim 48, characterized in that the compacting means, which is used to form compacts, is formed by a vibrating device.

51. A coking oven battery as claimed in any of claims 37 to 50, characterized in that it is equipped with a compacting means as claimed in any of claims 48 to 50.