The embodiments provide an acidic gas absorbent having low diffusibility, an acidic gas removal method employing the acidic gas absorbent, and also an acidic gas removal apparatus employing the absorbent. The acidic gas absorbent according to the embodiment comprises: a particular tertiary amine compound, such as, an alkyl dialkanol amine or a hydroxyalkyl piperazine; a halogen-free ionic surfactant; and an aqueous solvent. The embodiments provide not only the acidic gas absorbent but also an acidic gas removal method and apparatus employing the acidic gas absorbent.

The combined acid gas removal and water filtration system (10) removes sour gases, such as hydrogen sulfide (H2S) and carbon dioxide (CO2), from an input gaseous hydrocarbon stream (FG), as well as producing purified water (TW). The acid gas removal system (10) has a contactor (12) for contacting the input gaseous stream (FG) with an absorption liquid solvent (ALS), and a stripper (24) for recycling the absorption liquid solvent (ALS) and removing acidic gases (AG) therefrom. A first heat exchanger (22) heats used absorption liquid solvent (UALS) output from the contactor (12) prior to injection into the stripper (24). A second heat exchanger (26) cools recycled absorption liquid solvent (RALS) using a refrigerant (R) before injection back into the contactor (12). The refrigerant (R) is coupled with an absorber (84), which receives a dilute ethanolic draw solution (DDS) from a forward osmosis filtration system (72), producing purified water (TW).

A system and a process for capturing Carbon Dioxide (CO.sub.2) from flue gases are disclosed. The process comprises feeding a flue gas comprising CO.sub.2 to at least one Rotary Packed Bed (RPB) absorber rotating circularly. A solvent may be provided through an inner radius of the RPB absorber. The solvent may move towards an outer radius of the RPB absorber. The solvent may react with the flue gas in a counter-current flow. The process further includes passing the flue gas through at least one of a water wash and an acid wash to remove traces of the solvent present in the flue gas. Finally, the solvent reacted with the CO.sub.2 may be thermally regenerated for re-utilizing the solvent back in the process.

A system and a process for capturing Carbon Dioxide (CO.sub.2) from flue gases are disclosed. The process comprises feeding a flue gas comprising CO.sub.2 to at least one Rotary Packed Bed (RPB) absorber rotating circularly. A solvent may be provided through an inner radius of the RPB absorber. The solvent may move towards an outer radius of the RPB absorber. The solvent may react with the flue gas in a counter-current flow. The process further includes passing the flue gas through at least one of a water wash and an acid wash to remove traces of the solvent present in the flue gas. Finally, the solvent reacted with the CO.sub.2 may be thermally regenerated for re-utilizing the solvent back in the process.

The present invention relates to an absorption solvent and, more particularly, to an absorption solvent for removing carbon dioxide from a gaseous mixture having high carbon dioxide partial pressure.

The embodiments provide an acidic gas absorbent, an acidic gas removal method using the absorbent, and an acidic gas removal apparatus using the absorbent. The absorbent absorbs an acidic gas in a large amount and is hardly diffused. The acidic gas absorbent according to the embodiment comprises an amine compound represented by the following formula (1): ##STR00001##

A carbon dioxide absorbent of an embodiment includes a heterocyclic amine expressed by Formula (1), and the heterocyclic amine having a pKa of any one amino group included in a heterocyclic ring in Formula (1) in a range of 7.0 or more to 8.6 or less and an organic solvent having a boiling point of 150° C. or more at 1 atm. A total mass of the heterocyclic amine and the organic solvent is 70 mass % or more to 100 mass % or less of the carbon dioxide absorbent. Each of R.sup.1 to R.sup.4 in Formula (1) is H, oxygen double-bonded with carbon of the heterocyclic ring, CH.sub.3, OH, or an alkyl chain optionally including a functional group. X.sup.1 in Formula (1) is H, CH.sub.3, CO, C(O)OC.sub.2H.sub.5, C(O)OC.sub.3H.sub.7, C(O)OCH(CH.sub.3).sub.2, C(O)OC(CH.sub.3).sub.3, C(O)OCH.sub.3, C(O)CH.sub.3, or C(O)C.sub.2H.sub.5.

Methods and compositions useful, for example, for physical solvent carbon capture. The solvents may include an aqueous mixture of 2-amino-2-methylproponol, 2-piperazine-1-ethylamine, diethylenetriamine, 2-methylamino-2-methyl-1-propanol, and potassium carbonate or potassium carbonate buffer salt. The solvent may also contain less than about 75% by weight of dissolving medium (i.e., water) and may have a single liquid phase. The solvents and methods have favourable regeneration energies, chemical stability, vapour pressure, total heat consumption, net cyclic capacity, and reaction kinetics.

A plant for removing CO.sub.2 from a fluid stream via an aqueous absorption medium contains a) a first absorption zone for treating the fluid stream with a partially regenerated absorption medium, b) a second absorption zone for treating the treated fluid stream with a regenerated absorption medium, c) a first flash vessel for depressurizing the loaded absorption medium, d) a second flash vessel for depressurizing the sub-partially regenerated absorption medium, e) a stripper for thermally regenerating the partially regenerated absorption medium, f) a conduit for feeding a substream of the partially regenerated absorption medium into the first absorption zone and a conduit for feeding a further substream of the partially regenerated absorption medium into a stripper, g) a conduit for recirculating the regenerated absorption medium to the second absorption zone, and h) a jet pump for compressing the water vapor-comprising, second CO.sub.2-comprising gas stream.

An acidic gas absorbent contains an amine compound of formula (1) and a cyclic amino compound of formula (2) or (3): ##STR00001## ##STR00002## ##STR00003##
where in the formulas, each R.sup.1 is independently a straight-chain hydroxyalkyl having a hydroxy at the terminal, R.sup.2 is a branched-chain secondary alkyl group, R.sup.3 and R.sup.4 are hydrogen, hydroxy, a hydroxyalkyl or aminoalkyl, provided that at least one of R.sup.3 and R.sup.4s is a hydroxyalkyl or aminoalkyl, each p is independently an integer of 2 to 4, each R.sup.5 is independently hydrogen, hydroxy, or a hydroxyalkyl or aminoalkyl, provided that at least one of R.sup.5s is a hydroxyalkyl or aminoalkyl, and q is an integer of 3 to 8.