A carbon dioxide recovery system for collecting carbon dioxide from an exhaust gas generated in a facility including a combustion device includes: a first exhaust gas passage through which the exhaust gas containing carbon dioxide flows; a fuel cell including an anode, a cathode disposed on the first exhaust gas passage so that the exhaust gas from the first exhaust gas passage is supplied to the cathode, and an electrolyte transferring, from the cathode to the anode, a carbonate ion derived from carbon dioxide contained in the exhaust gas from the first exhaust gas passage; and a second exhaust gas passage diverging from the first exhaust gas passage upstream of the cathode so as to bypass the cathode. A part of the exhaust gas is introduced to the second exhaust gas passage.

A process for absorbing carbon dioxide from a gas stream containing carbon dioxide, including contacting the gas stream with an aqueous composition having a substituted heteroaromatic compound including a six-membered heteroaromatic ring comprising from 1 to 3 nitrogen atoms in the heteroaromatic ring and at least one substituent wherein at least one of the substituents is of formula —R.sup.1NH.sub.2 wherein R.sup.1 is selected from C.sub.1 to C.sub.6 alkylene and ethers of formula —R.sup.2—O—R.sup.3— wherein R.sup.2 and R.sup.3 are C.sub.1 to C.sub.3 alkylene.

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.

CO.sub.2 capture processes and systems can be improved by recovering thermal energy from particular streams for reuse in the stripping stage. Thermal energy can be recovered from the overhead gas stream of a stripper operated under vacuum pressure conditions, and thermal energy can also be recovered from a flue gas. A heat transfer circuit can be implemented for recovering thermal energy by indirect heat transfer from the overhead gas stream, a flue gas stream, and/or other streams to a heat transfer fluid. The heat transfer circuit can include multiple heat recovery loops arranged in parallel and the heated fluid can be supplied through a reboiler of the stripper to heat the solution in the reboiler.

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.

An absorption liquid regeneration apparatus includes: a regeneration tower for regenerating a CO.sub.2 absorption liquid; a reflux water drum configured to separate released gas from the regeneration tower into CO.sub.2 gas and condensed water, and return the condensed water to the regeneration tower; and a cleaning part installed in a gas-phase part of the reflux water drum or in a CO.sub.2 flow passage through which the CO.sub.2 gas having flowed from the gas-phase part flows, and configured to remove a CO.sub.2 absorption agent contained in the CO.sub.2 gas by using a cleaning liquid. The cleaning liquid has a lower concentration of the CO.sub.2 absorption agent than the condensed water stored in a liquid-phase part of the reflux water drum.

A hybrid post-combustion carbon dioxide capture system for capturing carbon dioxide from a flue gas includes a compressor adapted to produce a compressed flue gas stream, a membrane-based carbon dioxide separation unit configured to receive a first portion of the compressed flue gas stream from the compressor, and an aqueous-based carbon dioxide capture unit configured to receive a second portion of the compressed flue gas stream from the compressor whereby the compressed flue gas stream is processed in parallel by the membrane-based carbon dioxide separation unit and the aqueous-based carbon dioxide capture unit.

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.

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An apparatus for enhancing a yield and a transfer rate of a packed bed includes a packed bed, a vessel having a reaction chamber, a support frame and acoustic attenuator for holding the packed bed in the reaction chamber, at least one acoustic transducer adapted to transmit acoustic energy into the packed bed and an acoustic generator. The acoustic generator has impedance matching functionality.

The use of the combination of (a) an amino compound and (b) a compound including a soft electrophilic centre to scavenge and retain acidic sulfide species at a higher temperature and/or scavenge acidic sulfide species at an increased rate compared to that achieved using the amino compound alone.