Abstract: Disclosed are methods and systems for removing submicron particles from a gas stream, in particular from urea prilling off-gas, wherein a Venturi ejector is used. A method comprises contacting a gas stream containing submicron particles in a Venturi ejector with an injected high velocity scrubbing liquid to provide a pumping action, wherein the scrubbing liquid has an initial velocity of at least 2 m/s and wherein the ratio of scrubbing liquid and gas flow is between 0.0005 and 0.0015 (m3/h)/(m3/h). The disclosure also pertains to a prilling tower having a gas stream treatment system comprising a Venturi ejector at the top of the prilling tower, and to a method of modifying an existing prilling tower.

Abstract: Disclosed is an integrated process for the production of urea and melamine, as well as a system for carrying out the process. The invention thereby pertains to an integrated process of the type wherein off-gas obtained from the production of melamine is entered into the process for the production of melamine, by condensation in the presence of water. A typical embodiment thereof is the condensation in the presence of an aqueous carbamate solution obtained from urea recovery. In accordance with the invention, said condensation takes place at a substantially lower pressure than the pressure at which the melamine off-gas is obtained. To this end, the pressure of the off-gas is reduced typically by 2-10 bar. In connection herewith, the system of the invention comprises a pressure reducing unit downstream of an outlet for the melamine off-gas, and upstream of a section for the condensation of the off-gas.

Abstract: Disclosed is a dual pressure plant for the production of nitric acid on the basis of the oxidation of ammonia. The plant comprises a reactor configured to produce a burner gas stream; a gas cooling section configured to form a cooled burner gas; a condensation section configured to form an aqueous nitric acid condensate and an uncondensed nitrogen oxides gas stream; an absorption section configured to produce raw nitric acid and a tail gas; and a tail gas treatment system configured to form a purified tail gas. In a tail gas heating section a further heat exchanger configured to receive heat from the burner gas stream, said further heat exchanger being positioned relatively close to the reactor.

Abstract: Disclosed is a novel method of controlling the formation of biuret in urea production. This is accomplished by reducing or preventing the formation of biuret in a concentration section, particularly in one or more concentrators or evaporators. The method comprises controlling the residence time of a urea aqueous stream treated in such concentration section in a manner independently of the volume flow per time interval of said stream into said concentration section. The residence time can be controlled, e.g., by providing the concentration section with an adjustable volume or by adding a gas to the urea stream to be treated. A combination of such measures can also be applied.

Abstract: Disclosed is a novel method of controlling the formation of biuret in urea production, and particularly reducing, preventing or reversing such formation. This is accomplished by adding liquid ammonia to a urea aqueous stream. This addition is done at one or more positions downstream of a recovery section in a urea plant. The addition of liquid ammonia serves to shift the equilibrium of biuret formation from urea, to the side of the formation of urea from biuret and ammonia. The invention can be accomplished also in pre-existing urea plant, by the simple measure of providing an appropriate inlet for liquid ammonia, in fluid communication with a source of such liquid ammonia.

Abstract: Processes and plants for the production of purified urea solution are described. In a described urea production process, urea is produced in a synthesis section without a high pressure stripper and the urea solution is subjected to purification after the recovery section, to give purified urea solution and off-gas. The purification comprises e.g. steam stripping.

Abstract: The invention provides a method and a plant for producing urea ammonium nitrate (UAN). The method involves the use of a condensation section, optionally in combination with a medium pressure decomposition section, between the dissociation and neutralization sections. The invention further provides a method of modifying an existing UAN plant. The advantages of the process of the invention are that the emission of CO2 can be reduced, the plant capacity can be increased and the high capital expenditure needed for CO2 compression equipment is reduced.

Abstract: Disclosed is a method for the removal of urea dust from the off-gas of a finishing section of a urea production plant. the method comprises subjecting the off-gas to quenching with water so as to produce quenched off-gas, and subjecting the quenched off-gas to scrubbing using at least one venturi scrubber. As a result, a lower pressure drop over the scrubber is attained, and a more efficient growth of urea particles, facilitating the removal thereof.

Abstract: A method to start up and manage a combined cycle thermal plant for energy production comprising the execution according to a set sequence of a plurality of functional groups.

Abstract: Disclosed is a method of making a granulate of a urea product comprising urea and a salt, such as urea ammonium sulfate, having a high content of the salt. The high content is such as to provide an amount of the salt above the limit of solubility of the salt in urea. The granulate of the invention is characterized by having a smooth surface, which, e.g. in the event of urea ammonium sulfate, is not normally the case for granulate having the aforementioned high ammonium sulfate content. According to the invention this is realized by dividing the feed liquids to granulation. This division is based on non-final granulation liquids of a sufficiently high content of the salt, and a final granulation liquid (determining the surface) having a salt content of below the solubility limit of the salt, or no salt at all. E.g. in the event of urea ammonium sulfate, the non-final granulation liquids possibly are a slurry of urea and more than 20 wt. % of ammonium sulfate. The final granulation liquid then has 0-20 wt.

Abstract: Disclosed is a method for the removal of urea dust from the off-gas of a finishing section (1) of a urea production plant, the method comprises subjecting the off-gas to quenching with water (06) so as to produce quenched off-gas, and subjecting the quenched off-gas to scrubbing using at least one venturi scrubber (11). As a result, a lower pressure drop over the scrubber is attained, and a more efficient growth of urea particles, facilitating the removal thereof.

Abstract: The present invention provides a method for increasing the capacity of a urea production complex, the method comprising a step of adding to an existing urea production complex a CO2 production unit, which unit employs a CO2 production method comprising: i) subjecting a hydrocarbon feed to short contact time catalytic partial oxidation (SCT-CPO) to produce a first gas mixture comprising H2, CO and CO2, ii) subjecting said first gas mixture to a water gas shift reaction yielding a second gas mixture, iii) separating CO2 from said second gas mixture yielding a purified CO2 stream and a hydrogen containing stream and subsequently iv) reacting said purified CO2 stream with ammonia from the ammonia production unit to produce urea. The invention also provides a urea production complex realized by the application of this method and a urea production method.

Abstract: Disclosed is a urea plant wherein, in deviation from conventional plants, a high-pressure synthesis section is operated with two different pressures. The synthesis section comprises a reactor, which is operated under a first high pressure. The synthesis section also comprises a stripper and a condenser, both operated at substantially the same second high pressure. In accordance with the invention, the first pressure is substantially higher than the second pressure. The disclosed plant particularly comprises a compression unit capable of converting a pressure difference into work, or more specifically, mechanical energy for compression. This compression unit is positioned between a liquid outlet of the condenser and a liquid inlet of the reactor, and in fluid communication therewith. In order to make use of a pressure drop (expansion as a result of a liquid being depressurized), said compression unit is configured to obtain compression energy from one or more events in the urea production process (i.e.

Abstract: The invention relates to a process for the production of urea ammonium nitrate, a system and a method of modifying a plant. The process comprises subjecting ammonia-containing off-gas resulting from the production of ammonium nitrate (AN off-gas) to condensation under acidic conditions so as to form an acidic condensate, and using at least part of the acidic condensate as an acidic scrubbing liquid in a finishing treatment section having a gas inlet in fluid communication with a gas outlet of a finishing section of a urea production unit, wherein the finishing section is adapted to solidify urea liquid, and wherein said finishing treatment section is adapted to subject ammonia-containing off-gas of the finishing section to treatment with an acidic scrubbing liquid.

Abstract: Disclosed is a method for the removal of urea dust from the off-gas of a finishing section of a urea production plant. the method comprises subjecting the off-gas to quenching with water so as to produce quenched off-gas. The quenched off-gas is subjected to humidification by mixing said quenched gas stream with a humidification fluid selected from (a) saturated steam and (b) superheated steam mixed with a second aqueous stream, so as to produce a humidified gas stream, subjecting said humidified gas stream to particle separation (i.e., dust removal) by means of a scrubbing liquid in which at least part of the particles in the gas stream are soluble.

Abstract: Disclosed is a Hot Isostatic Pressed ferritic-austenitic steel alloy, as well objects thereof. The elementary composition of the alloy comprises, in percentages by weight: C ?0-0.05; Si 0-0.8; Mn 0-4.0; Cr more than 29-35; Ni 3.0-10;? Mo 0-4.0; N 0.30-0.55:? Cu 0-0.8; W 0-3.0; S ?0-0.03; Ce 0-0.2; the balance being Fe and unavoidable impurities. The objects can be particularly useful in making components for a urea production plant that require processing such as machining or drilling. A preferred use is in making, or replacing, liquid distributors as used in a stripper as is typically present in the high-pressure synthesis section of a urea plant.

Abstract: The invention relates to a process for the production of urea ammonium nitrate, a system and a method of modifying a plant. The process comprises treating ammonia-containing off-gas resulting from the production of ammonium nitrate (AN off-gas) with acidic scrubbing liquid in a finishing treatment section having a gas inlet in fluid communication with a gas outlet of a finishing section of a urea production unit, wherein the finishing section is adapted to solidify urea liquid, and wherein said finishing treatment section is adapted to subject ammonia-containing off-gas of the finishing section to treatment with an acidic scrubbing liquid.

Abstract: Disclosed is a method for the production of hydrogen from a H2S-containing gas stream also containing ammonia, comprising subjecting both gas stream to catalytic oxidative cracking of both the H2S and the NH3, so as to form H2, S2 and N2. In this method, preferably, an additional amount of oxygen is added as compared to the amount used for H2S catalytic oxidative cracking. Also, preferably, the contact time of the gas stream with the catalyst is increased. The catalyst preferably is provided as a single bed, and then preferably comprises iron and molybdenum supported by a carrier comprising aluminum. The preferred carrier is alumina. The iron and molybdenum preferably are in the form of sulfides.

Abstract: Disclosed is a Hot Isostatic Pressed ferritic-austenitic steel alloy, as well objects thereof. The elementary composition of the alloy comprises, in percentages by weight: C 0-0.05; Si 0-0.8; Mn 0-4.0; Cr more than 29-35; Ni 3.0-10; Mo 0-4.0; N 0.30-0.55; Cu 0-0.8; W 0-3.0; S 0-0.03; Ce 0-0.2; the balance being Fe and unavoidable impurities. The objects can be particularly useful in making components for a urea production plant that require processing such as machining or drilling. A preferred use is in making, or replacing, liquid distributors as used in a stripper as is typically present in the high-pressure synthesis section of a urea plant.

Abstract: In the present invention a method for treating algae is disclosed, which method comprises the steps of (a) providing an ionic liquid, which is a conjugate of an organic base with pKa at least 6 and an acid, (b) providing algae, (c) subjecting algae to cell lysis with the ionic liquid, whereby at least two phases are formed, including a hydrophobic phase and a hydrophilic phase, and (d) separating the hydrophobic phase containing lipids.