A solution including at least one mixed acetal compound is used to remove hydrogen sulfide and/or mercaptans from a fluid stream, preferably a fluid gas stream. A mixed acetal compound, as provided in the general structure below, includes an N-glycosidic type bond. The mixed acetal includes nitrogen and oxygen as provided below. ##STR00001##

Disclosed is a system and method of separating and collecting acid gas such as carbon dioxide in which the energy consumption in a stripping column for regenerating an absorbent may be reduced. In the system and method, the energy consumption may be reduced using heat generated during the acidic gas separation and collection processes. In the system and method, a low-temperature condensate from a condenser may be preheated by heat exchange with a high-temperature processed gas, and then supplied into the stripping column, thereby to reduce the heat duty of a reboiler and the energy consumption in the condenser for cooling. A partial flow of a carbon diode-absorbed absorbent from an absorber column may be preheated by heat exchange with high-temperature processed gas from an upper portion of the stripping column, and then supplied into the stripping column, thereby to further reduce the heat duty of the reboiler.

A process and a plant for purifying a crude gas stream containing sulfur components and hydrocarbons by gas scrubbing using a scrubbing medium which is selective for sulfur components in an absorption column. Heavy hydrocarbons and heavy mercaptans are removed from the crude gas in a lower section of the absorption column and the resulting, loaded scrubbing medium stream is fed separately from the other loaded scrubbing medium streams to a hot regeneration column. A vapor stream enriched in water, hydrocarbons and sulfur components is obtained as overhead product from the hot regeneration column and this stream is cooled to below its dew point and is separated in a gas-liquid-liquid phase separation apparatus. The resulting, organic liquid phase contains heavy hydrocarbons and heavy mercaptans and can thus be discharged from the process or the plant, as a result of which accumulation thereof in the scrubbing medium is prevented.

A gas exchange system, said system comprising: a plurality of cartridges, each having a casing, said casing having a cartridge inlet adjacent to a first end and a cartridge outlet adjacent to an opposed second end; each casing having a bore in which is placed a gas permeable, liquid impermeable, hollow membrane; each hollow membrane having a membrane inlet arranged to receive a gas from an inlet chamber and a membrane outlet for venting said gas; each cartridge inlet in communication with a concentration zone, and arranged to receive a solvent from said concentration zone, so as to exit said solvent through said cartridge outlet; wherein said bore is arranged to flow said solvent adjacent to said hollow membrane so as to permit the exchange of gas through said gas permeable, liquid impermeable membrane.

Disclosed is an adsorbent containing a metal oxide for adsorption of hydrogen sulfide in biogas, and a biogas purification system using the same.

An absorbent for selective removal of hydrogen sulfide over carbon dioxide from a fluid stream comprises an aqueous solution of a) a tertiary amine, b) a sterically hindered secondary amine of the general formula (I) ##STR00001##
in which R.sub.1 and R.sub.2 are each independently selected from C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are each independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl, with the proviso that at least one R.sub.4 and/or R.sub.5 radical on the carbon atom bonded directly to the nitrogen atom is C.sub.1-4-alkyl or C.sub.1-4-hydroxyalkyl when R.sub.3 is hydrogen; x and y are integers from 2 to 4 and z is an integer from 1 to 4; where the molar ratio of b) to a) is in the range from 0.05 to 1.0, and c) an acid in an amount, calculated as neutralization equivalent relative to the protonatable nitrogen atoms in a) and b), of 0.05 to 15.0%. One preferred amine of the formula I is 2-(2-tert-butylaminoethoxy)ethanol. The absorbent allows a defined H.sub.2S selectivity to be set at pressures of the kind typical in natural gas processing.

A process and apparatus for managing hydrogen sulfide in a refinery is provided. In the process, a hydrogen sulfide stream from said refinery is fed to a sulfur recovery unit to produce sulfur and a sulfur compound stream or to a thermal oxidizer. The sulfur compound stream and the hydrogen sulfide stream are then thermally oxidized to produce a sulfur oxide stream. The sulfur oxide stream is then reacted with an ammonia stream. In aspect, the product of the reaction can be a fertilizer. The ammonia stream can be obtained from stripping the hydrogen sulfide stream.

Methods and systems for treating an olefin-containing stream are disclosed. The disclosed methods and systems are particularly suitable for treating an off-gas stream in a refining or petrochemical process, such as from a fluid catalytic cracker (FCC), coker, steam cracker, and the like. The stream is treated in an absorber column to reject lighter stream components and to absorb ethylene and/or propylene into a solvent. The solvent is typically isobutane. The enriched solvent stream from the absorber column is fed to an alkylation reactor, which reacts the dissolved olefin with the isobutane solvent to produce an alkylate product.

The embodiments provide an acidic gas absorbent kept from deterioration, an acidic gas removal method using the absorbent, and an acidic gas removal apparatus using the same. The acidic gas absorbent contains an amine compound and water, and further contains superfine bubble containing inert gas wherein an average diameter of said superfine bubble is 150 nm or less. The acidic gas removal method provided here employs that absorbent. The acidic gas removal apparatus is equipped with a unit for introducing the superfine bubbles into the absorbent.

The invention relates to a process and a plant for removing thiols from synthesis gas. Thiols and optionally thiophene and carbon disulfide are absorbed in a dedicated absorption stage with methanol as physical absorption medium. Methanol laden with at least thiols is freed of thiols in a stripping stage with methanol vapours as stripping gas and the methanol vapours-containing thiols are freed of methanol in a scrubbing stage. The process according to the invention minimizes methanol losses and the amounts of coolant required for the process.