Processes and apparatuses for treating a sour synthesis gas are provided. The process comprises passing the sour synthesis gas stream to an acid gas removal unit to provide a treated synthesis gas stream and a CO.sub.2 rich stream. At least a portion of the CO.sub.2 rich stream is passed to a thermal oxidizer unit to provide a treated CO.sub.2 gas stream. At least a portion of the treated synthesis gas stream is passed to a pressure swing adsorption unit to obtain a purified hydrogen stream and a tail gas stream. At least a portion of the tail gas stream is passed to the thermal oxidizer unit.

Disclosed herein are acid gas absorbents that afford high acid gas (CO2) absorption amount per unit volume and high absorption speed and can prevent the absorbent components from diffusing. Also disclosed herein is a method and device for removing an acid gas, in which the energy required for separating the acid gas and regenerating the absorbent is reduced, are provided.

Disclosed is a process comprising: step a) contacting a feed stream comprising a contaminant with an absorbent stream in a counter-current flow to produce a contaminant depleted product stream depleted in the molar quantity of the contaminant relative to the molar quantity of said contaminant in the feed stream, and a contaminant enriched absorbent stream enriched in the molar quantity of the contaminant relative to the molar quantity of said contaminant in the absorbent stream; and step b) treating the contaminant enriched absorbent stream to form a gaseous stream comprising said contaminant and a regenerated absorbent stream lean in the molar quantity of said contaminant relative to the molar quantity of said contaminant in the contaminant enriched absorbent stream; herein said absorbent stream comprises at least 15 wt. % of at least one compound (A) of general formula (I) or a mixture (M) comprising at least one compound (B) of general formula (II) and at least one compound (C) of general formula (III).

Solvent absorption processes for separating components of an impure feed gas are disclosed. The processes involve two stages of gas purification. The acid gases including hydrogen sulfide, carbon dioxide and other sulfur compounds are simultaneously removed from the feed gas by contact with a physical solvent in two stages. The subject matter disclosed provides improved processes to reduce the operating costs of the system.

An absorbent mixture for the removal of acid gases from gas mixtures includes: A) at least one alcohol of general formula R(OH).sub.n, wherein R is an optionally substituted linear or branched alkyl or alkylaromatic group, with 2-20 carbon atoms and n is an integer that varies between 1-20; B) at least one organic base with a pK.sub.b (in water) less than or equal to 3; C) a solvent based on one or more heterocyclic compounds selected from cyclic ureas with a 5 or 6 atom ring of formula (IV) and/or (V); cyclic lactams with a 5 or 6 atom ring of formula (VI) and/or (VII); or combinations thereof:

##STR00001##

Where R1, R2, R3, R4 are independently selected from H, alkyl groups, linear or branched, with 1-10 carbon atoms;

##STR00002##

Where R1 and R3 are independently selected from H, alkyl, linear or branched groups with 1-10 carbon atoms.

A plant comprises a feed gas source, H2S removal unit, first absorber and a second, pressure reduction stages, first and second heat exchangers, stripping unit, and a conduit. The H2S removal unit selectively removes H2S from a feed gas from the feed gas source to produce an H2S depleted feed gas. The first absorber and the second absorber remove CO2 from the H2S depleted feed gas using a semi-lean and an ultralean solvent to produce a product gas and a rich solvent. The plurality of pressure reduction stages generates a cooled flashed solvent. The first heat exchanger and the second heat exchanger use the cooled flashed solvent to cool the H2S depleted feed gas and the semi-lean solvent. The stripping unit strips the flashed solvent with dried air to produce the ultralean solvent, and the conduit combines a portion of the ultralean solvent with the H2S depleted feed gas.

Solvent absorption processes for separating components of an impure feed gas are disclosed. The processes involve two stages of gas purification. The acid gases including hydrogen sulfide, carbon dioxide and other sulfur compounds are simultaneously removed from the feed gas by contact with a physical solvent in two stages. The subject matter disclosed provide improved processes and apparatus to reduce the operating costs of the system.

Processes and apparatuses for treating a sour synthesis gas are provided. The process comprises passing the sour synthesis gas stream to an acid gas removal unit to provide a treated synthesis gas stream and a CO.sub.2 rich stream. At least a portion of the CO.sub.2 rich stream is passed to a thermal oxidizer unit to provide a treated CO.sub.2 gas stream. At least a portion of the treated synthesis gas stream is passed to a pressure swing adsorption unit to obtain a purified hydrogen stream and a tail gas stream. At least a portion of the tail gas stream is passed to the thermal oxidizer unit.

The present invention relates to a process for producing hydrogen and for separating carbon dioxide from synthesis gas using a physical absorption medium. The process comprises the steps where the synthesis gas and the absorption medium are cooled; carbon dioxide is removed from the cooled synthesis gas via the cooled absorption medium in a physical absorption step at elevated pressure; laden absorption medium is treated in a plurality of flash stages, wherein co-absorbed carbon monoxide, hydrogen and carbon dioxide are separately removed from the laden absorption medium; hydrogen is separated from synthesis gas freed of carbon dioxide in a physical separation step, wherein hydrogen as product gas and an offgas comprising hydrogen, carbon monoxide and carbon dioxide are obtained; product gas hydrogen and carbon dioxide are discharged from the process. The invention further relates to a plant for performing the process.

A plant comprises a feed gas source, H2S removal unit, first absorber and a second, pressure reduction stages, first and second heat exchangers, stripping unit, and a conduit. The H2S removal unit selectively removes H2S from a feed gas from the feed gas source to produce an H2S depleted feed gas. The first absorber and the second absorber remove CO2 from the H2S depleted feed gas using a semi-lean and an ultralean solvent to produce a product gas and a rich solvent. The plurality of pressure reduction stages generates a cooled flashed solvent. The first heat exchanger and the second heat exchanger use the cooled flashed solvent to cool the H2S depleted feed gas and the semi-lean solvent. The stripping unit strips the flashed solvent with dried air to produce the ultralean solvent, and the conduit combines a portion of the ultralean solvent with the H2S depleted feed gas.