A plant and process for producing a hydrogen rich gas are provided, said process comprising the steps of: reforming a hydrocarbon feed in a reforming step thereby obtaining a synthesis gas comprising CH.sub.4, CO, CO.sub.2, H.sub.2 and H.sub.2O; shifting said synthesis gas in a shift configuration including a high temperature shift step; removal of CO.sub.2 upstream hydrogen purification unit, such as a pressure swing adsorption unit (PSA), and recycling off-gas from hydrogen purification unit and mix it with natural gas upstream prereformer feed preheater, prereformer, reformer feed preheater or ATR or shift as feed for the process.

Provided are a process and a system for treating both a high-pressure (HP) and a low-pressure (LP) acid gas-containing gas streams. The system includes a HP absorber unit, a flash drum coupled downstream of the HP absorber unit, and a LP absorber unit coupled downstream of the flash drum. The process includes introducing a HP rich amine solution from a HP absorber unit into a flash drum, operating the flash drum such that a flashed sour gas and a flash drum rich amine solution are produced, and introducing the flashed sour gas and the LP acid gas-containing gas stream into a LP absorber unit.

Provided are a process and a system for treating both a high-pressure (HP) and a low-pressure (LP) acid gas-containing gas streams. The system includes a HP absorber unit, a flash drum coupled downstream of the HP absorber unit, and a LP absorber unit coupled downstream of the flash drum. The process includes introducing a HP rich amine solution from a HP absorber unit into a flash drum, operating the flash drum such that a flashed sour gas and a flash drum rich amine solution are produced, and introducing the flashed sour gas and the LP acid gas-containing gas stream into a LP absorber unit.

A process and plant for producing a high purity CO.sub.2 product, comprising: providing a CO.sub.2-rich stream containing hydrocarbons, hydrogen and/or CO, combining it with a stream rich in methane (CH.sub.4), and mixing it with oxygen, thereby forming a CO.sub.2/O.sub.2- mixture; subjecting the CO.sub.2/O.sub.2- mixture to a catalytic oxidation step, thereby producing a purified stream having a higher CO.sub.2 and/or H.sub.2O concentration; removing H.sub.2O from said purified stream, for producing said high purity CO.sub.2 product stream. The CO.sub.2-rich stream is for instance derived from the CO.sub.2-removal section of a plant for producing hydrogen.

A process and plant for producing a high purity CO.sub.2 product, comprising: providing a CO.sub.2-rich stream containing hydrocarbons, hydrogen and/or CO, combining it with a stream rich in methane (CH.sub.4), and mixing it with oxygen, thereby forming a CO.sub.2/O.sub.2- mixture; subjecting the CO.sub.2/O.sub.2- mixture to a catalytic oxidation step, thereby producing a purified stream having a higher CO.sub.2 and/or H.sub.2O concentration; removing H.sub.2O from said purified stream, for producing said high purity CO.sub.2 product stream. The CO.sub.2-rich stream is for instance derived from the CO.sub.2-removal section of a plant for producing hydrogen.

The present invention relates to a process for removing carbon dioxide from synthesis gas using a hygroscopic, physical absorption medium. The process includes cooling the absorption medium and the synthesis gas; water is at least partially removed from the synthesis gas by condensation; 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 serially arranged flash stages, wherein co-absorbed carbon monoxide and hydrogen are removed from the laden absorption medium in at least one first flash stage, and carbon dioxide is removed from the laden absorption medium in a flash stage arranged downstream of the first flash stage. The process features a high rate of separated carbon dioxide and a pure and dry (anhydrous) carbon dioxide product. The invention further relates to a plant for performing the process.

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.

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.

It has been discovered that mixed-alcohol production can utilize the waste tail gas stream from the pressure-swing adsorption section of an industrial hydrogen plant. Some variations provide a process for producing mixed alcohols, comprising: obtaining a tail-gas stream from a methane-to-syngas unit (e.g., a steam methane reforming reactor); compressing the tail-gas stream; separating the tail-gas stream into at least a syngas stream, a CO.sub.2-rich stream, and a CH.sub.4-rich stream; introducing the syngas stream into a mixed-alcohol reactor operated at effective alcohol synthesis conditions in the presence of an alcohol-synthesis catalyst, thereby generated mixed alcohols; and purifying the mixed alcohols to generate a mixed-alcohol product. Other variations provide a process for producing clean syngas, comprising: obtaining a tail-gas stream from a methane-to-syngas unit; compressing the tail-gas stream; separating the tail-gas stream into at least a syngas stream, a CO.sub.2-rich stream, and a CH.sub.4-rich stream; and recovering a clean syngas product.

A hydrogen feed stream comprising one or more impurities selected from the group consisting of nitrogen, argon, methane, carbon monoxide, carbon dioxide, oxygen, and water, is contacted with liquid hydrogen in a cryogenic wash column (CWC) process that produces pure hydrogen with high overall recovery. The waste liquid stream leaving the CWC may be used to improve the performance of upstream hydrogen processing steps.