Abstract: Organic solvents are removed from air by adsorption on fixed beds of activated carbon. Each carbon bed is periodically regenerated by heating it in two distinct steps and then by cooling it in two steps with a circulated inert gas stream. During the first step of heating a portion of the water is removed from the inert gas by molecular sieves or preferably by chilling the inert gas to below 10.degree. C. In a second step of heating the essentially water-free liquid solvent is recovered by chilling the inert gas. The first step of cooling of a bed is overlapping with the first step of heating of another bed. The hot gas leaving the cooled bed is used to heat the other bed. Between the two stages of heating the bed is put on "hold" till the final cooling step of another bed is completed.

Abstract: The process for making phthalic anhydride by catalytic gas phase oxidation of o-xylene or naphthalene includes feeding a gas containing oxygen and the reactant to a first reactor; operating the first reactor to oxidize the reactant and obtain an effluent gas including the reactant, phthalic anhydride and/or maleic anhydride; adding the reactant or a gas containing the reactant to the effluent so that a molar ratio of moles of free oxygen to a sum of moles of the organic compounds in the effluent is less than 7, preferably from 3 to 6; after that, feeding the effluent into a second reactor; and operating the fixed bed reactor to at least partially convert the reactant in the effluent to phthalic anhydride.

Abstract: A method of and an apparatus for producing an air-ammonia mixture for use in production of nitric acid and for producing refrigeration wherein liquid ammonia is evaporated in a heat exchanger to obtain ammonia vapor and accompanying refrigeration, the ammonia vapor is absorbed by a lean ammonia solution to obtain a rich ammonia solution, ammonia from the rich ammonia solution is stripped with air whereby an air-ammonia mixture, a lean ammonia solution, and additional refrigeration is obtained, and the lean ammonia solution obtained as a result of stripping ammonia from the rich ammonia solution with air is used for absorbing further ammonia vapor for producing a further rich ammonia solution.

Abstract: Integrated primary-secondary reforming operations are carried out with the partly reformed product effluent from the reformer tubes of the primary reforming zone passing to a catalyst-free reaction space at the feed end of a catalyst bed in the secondary reforming zone. The exothermic heat of reaction generated in said reaction space supplies the necessary heat for the endothermic reforming reaction that occurs in the catalyst bed of the secondary reforming zone, and the still hot secondary product effluent leaving the secondary reforming zone is passed in the shell side of the primary reformer zone to supply the endothermic heat of reaction required in said primary reforming zone. Essentially autothermal operating conditions are thereby achieved so as to essentially eliminate the necessity for employing an external fuel-fired primary reformer and/or for consuming a portion of the hyrocarbon feed material for fuel purposes.

Abstract: An apparatus for the production of ammonia synthesis gas comprises a hydrocarbon convertor for converting a hydrocarbon feed to an effluent containing hydrogen and carbon monoxide by reaction with air which hydrocarbon convertor includes means to provide air in excess of the stoichiometric amount of nitrogen required for ammonia synthesis. The effluent from the hydrocarbon convertor is in communication with a water gas shift convertor for converting the carbon monoxide in the effluent to carbon dioxide. The water gas shift convertor is in communication with a pressure-swing adsorption system capable of selectively adsorbing carbon dioxide, carbon monoxide, methane and other impurities from hydrogen and a portion of the nitrogen fed in the gas mixture to the pressure swing adsorption system. The pressure swing adsorption system is provided with a conduit for discharging a partially purified ammonia synthesis gas mixture of hydrogen and nitrogen and a conduit for discharging purge gas.

Abstract: Carbon monoxide is recovered as the intermediate component of a reformer effluent containing hydrogen, carbon monoxide and carbon dioxide in a pressure swing adsorption system by the introduction of a gas displacement step before, simultaneous with or subsequent to pressure equalization between beds of a multi-bed adsorption system, with a cocurrent depressurization step being employed to recover said CO product. The carbon dioxide-rich countercurrent depressurization and/or purge effluent is recycled to the reformer for reaction with natural gas or other feed gas, with no carbon dioxide scrubbing step being employed before passage of the reformer effluent to the pressure swing adsorption system.

Abstract: A pressure swing adsorption process is disclosed wherein binary gas purification is effected from a single adsorbent bed. An adsorbent bed is charged under pressure with a gas mixture having some components that are more adsorbable than others. The process causes the bed to be polarized with one end of the bed containing the more adsorbable components and the other end containing the less adsorbable components. Once charged, the bed is depressurized simultaneously from both ends, thus removing the separated components from their respective ends.

Abstract: Integrated primary-secondary reforming operations are carried out with the partly reformed product effluent from the reformer tubes of the primary reforming zone passing to a catalyst-free reaction space at the feed end of a catalyst bed in the secondary reforming zone. The exothermic heat of reaction generated in said reaction space supplies the necessary heat for the endothermic reforming reaction that occurs in the catalyst bed of the secondary reforming zone, and the still hot secondary product effluent leaving the secondary reforming zone is passed in the shell side of the primary reformer zone to supply the endothermic heat of reaction required in said primary reforming zone. Essentially autothermal operating conditions are thereby achieved so as to essentially eliminate the necessity for employing an external fuel-fired primary reformer and/or for consuming a portion of the hydrocarbon feed material for fuel purposes.

Abstract: A fluid hydrocarbon feed stream is converted with excess air to a mixture of hydrogen and carbon monoxide, also containing the nitrogen content of said air. Following high temperature shift conversion to convert said carbon monoxide to hydrogen and carbon dioxide, the gas mixture is passed to a pressure saving adsorption system used to produce an impure ammonia synthesis gas mixture of hydrogen and nitrogen, with excess nitrogen being separated and removed therefrom with the impurities discharged from the system at high operating pressures, the purge gas effluent from the pressure swing adsorption system can be passed to an expansion turbine for desirable power energy. The ammonia synthesis gas, which can be passed to a methanator for final purification, is thus produced without the need for employing an air separation plant or a nitrogen plant.

Abstract: The reformed gas mixture to be employed for ammonia synthesis is purified, following shift conversion, by the selective catalytic oxidation of residual carbon monoxide and the selective adsorption of carbon dioxide and water so as to render unnecessary the methanation of carbon oxides.

Abstract: Effluent gas streams for steam reforming, partial oxidation or coal gasification operations are advantageously treated in shift conversion, scrubbing and pressure swing adsorption units for recovery of a purified, hydrogen-containing product gas stream. By recycling a portion of the waste gas removed from the pressure swing adsorption system to the shift conversion unit and/or to the effluent gas generation operation, enhanced product recovery is achieved without the necessity for employing low temperature shift or for achieving essentially complete removal of the carbon dioxide content of the gas being treated prior to its passage to said pressure swing adsorption system.

Abstract: A pressure swing adsorption process is used to achieve intermediate product recovery by the introduction of a gas displacement step before, simultaneous with or subsequent to pressure equalization between beds of a multi-bed adsorption system. A cocurrent depressurization step is then employed to achieve intermediate product recovery. A portion of said intermediate product or of the more readily adsorbable component recovered from a bed advantageously being employed to provide displacement gas for another bed in the adsorption system.

Abstract: The heat capacity of activated carbon adsorbent pellets is enhanced by the mixing of activated carbon powder with a higher heat capacity, inert inorganic material, such as dense alumina, prior to pelletizing. The resulting doped adsorbent enhances the operation of adiabatic pressure swing adsorption processes by decreasing the cyclic temperature change in the adsorbent bed during each processing cycle of the process.

Abstract: In pressure swing adsorption processing including higher pressure adsorption, cocurrent depressurization to intermediate pressure, countercurrent depressurization and/or lower pressure purge and repressurization, a cocurrent purge step is employed at adsorption pressure prior to cocurrent depressurization. Methane or natural gas is advantageously employed as the cocurrent purge gas. The cocurrent purge step reduces the storage of product gas, such as hydrogen, in the bed, enhances product recovery and correspondingly reduces the amount of desired product gas discharged with the waste gas discharged the countercurrent depressurization and/or purge steps used for bed regeneration. The value of the waste gas as a fuel is likewise enhanced by the presence of said methane or natural gas therein.

Abstract: In pressure swing adsorption systems having at least five adsorbent beds, three or more cocurrent depressurization-pressure equalization steps are employed in each processing cycle. At least one indirect equalization step is employed between two direct pressure equalizations in which void space gas released from the product end of a bed is passed directly to another bed initially at lower pressure so as to equalize the pressure therebetween. In such indirect pressure equalization step, said void space gas is introduced into an external storage tank from which it is passed to a bed being repressurized for indirect pressure equalization between two direct equalization steps in the repressurization of said bed. Sequential direct-indirect-direct-indirect or indirect-direct-indirect-direct processing steps are preferred.

Abstract: The hot effluent from the catalytic steam reforming of a major portion of a fluid hydrocarbon feed stream in the reformer tubes of a primary reformer, or said effluent after secondary reforming thereof, is mixed with the hot effluent from the catalytic steam reforming of the remaining portion of the feed discharged from the reformer tubes of a primary reformer-exchanger. The combined gas stream is passed on the shell side of the reformer-exchanger countercurrently to the passage of feed in the reformer tubes thereof, thus supplying the heat for the reforming of the portion of the feed passed through the reformer tubes of the reformer-exchanger. At least about 2/3 of the hydrocarbon feed stream is passed to the reformer tubes of said primary reformer, heated by radiant heat transfer and/or by contact with combustion gases, at a steam/hydrocarbon mole ratio of about 2-4/1.

Abstract: In a pressure swing adsorption system for the purification of hydrogen to be used in an ammonia synthesis gas, nitrogen is employed as a purge gas at an elevated purge pressure. The hydrogen recovered at adsorption pressure contains about 20-25% nitrogen and is advantageous for use as said ammonia synthesis gas. The purge gas is expanded to generate power that can be used to compress air being passed to an air separation system. The nitrogen recovered therein can be employed as said purge gas, while the oxygen recovered can conveniently be employed in a hydrogen generation system used to form said hydrogen passed to the pressure swing adsorption system.

Abstract: Bed utilization and product recovery are enhanced in pressure swing adsorption operations, especially for high pressure applications, by terminating cocurrent depressurization at a relatively high intermediate pressure level. Additional void space gas is released from each main adsorption bed by partial countercurrent depressurization prior to conventional countercurrent blowdown. Such additional gas is passed to a satellite bed adapted for simultaneous release of gas from its discharge end, thereby cocurrently depressurizing said satellite bed from said intermediate pressure level, with the thus-released gas being passed to the discharge end of another satellite bed or beds and/or another main bed or beds for pressure equalization and/or purging purposes. The satellite bed is one of a satellite group of adsorption beds containing a lesser number and smaller beds than in said main bed system, the satellite beds not being operated above said intermediate pressure level.

Abstract: A process for forming a gas mixture containing hydrogen and nitrogen for ammonia synthesis, wherein a feed gas mixture containing hydrogen and adsorbable impurities is separated by selective adsorption of the impurities in each of multiple adsorbent beds and discharge of unadsorbed hydrogen-rich gas.

Abstract: Normal paraffins are separated from a hydrocarbon vapor feedstream having 10 to 25 carbon atoms per molecule in a constant pressure process employing a molecular sieve adsorbent and n-hexane for purging and for dilution of gas oil - containing feedstocks. A portion of the countercurrent, desorption purge effluent is employed as a hexane - containing cocurrent purge stream, thereby significantly reducing the required amount of n-hexane purge recycle material, and the size of the equipment and the energy consumed in the processing of said recycle stream. A portion of said countercurrent purge effluent can also be used to provide a source of n-hexane diluent for the gas oil - containing feedstocks, as can the cocurrent purge effluent, resulting in further reduction in required equipment and energy costs, and increasing adsorption efficiency and adsorbent utilization.