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 method for regenerating carbon dioxide and hydrogen sulfide from acid gas using a catalyst containing a group 2 element is provided. The method reduces the energy required for the regeneration process and allows for an efficient and cost-effective way to regenerate acid gas.

An integrated amine and redox gas treatment system is configured to treat an influent hydrocarbon containing stream. The system includes a reduction oxidation unit connected directly downstream of an amine unit. The amine unit is configured to separate the influent fluid stream into a first amine effluent stream including hydrocarbons and a second amine effluent stream including a connection pressure and comprising CO.sub.2. The reduction oxidation unit is configured to receive the second amine effluent stream from the amine unit and operate at the connection pressure while releasing a reduction oxidation effluent stream including purified CO.sub.2. The connection pressure includes a single pressure or a plurality of pressures at which both the amine unit and the reduction oxidation unit are configured to operate.

A treatment process for remediating contaminants in a mixture of contaminated fluids, including at least one liquid fluid and at least one gaseous fluid, includes the steps of: preparing a liquid treatment composition containing at least 80 volume % of an aqueous solution containing at least one hydroxide compound at a collective concentration of 35-55 weight percent, and at least one of fulvic acid and humic acid at a collective concentration of 0.1-5 wt % of the treatment composition; adding a dosage of the treatment composition to a mixture of contaminated fluids including a liquid portion and a gaseous portion; and allowing the treatment composition to react with the mixture of contaminated fluids for at least 10 minutes, wherein a pH of the treatment composition is at least 13.0 and the aqueous solution contains at least one of NaOH and KOH.

A composite amine absorbent to absorb at least one of CO.sub.2 and H.sub.2S in a gas includes: a chain monoamine; a diamine; a cyclic compound represented by the following chemical formula:

##STR00001##

where R.sup.1: any one of hydrogen, a hydrocarbon group having a carbon number of 1 to 4, and a hydroxyalkyl group, R.sup.2: oxygen or NR.sup.3, and R.sup.3: any one of hydrogen, a hydrocarbon group having a carbon number of 1 to 4, and a hydroxyalkyl group; and water.

The disclosure includes a method, comprising passing a fluid into a co-current contactor, passing a solvent into the co-current contactor, dividing the solvent into solvent droplets having a first average droplet size, placing the fluid in contact with the solvent droplets to create a combined stream, coalescing at least a portion of the solvent droplets to create solvent droplets having a second average droplet size, wherein the second average droplet size is greater than the first average droplet size, and separating the fluid and the solvent.

The disclosure includes a method, comprising passing a fluid into a co-current contactor, passing a solvent into the co-current contactor, dividing the solvent into solvent droplets having a first average droplet size, placing the fluid in contact with the solvent droplets to create a combined stream, coalescing at least a portion of the solvent droplets to create solvent droplets having a second average droplet size, wherein the second average droplet size is greater than the first average droplet size, and separating the fluid and the solvent.

The present disclosure includes systems and methods that integrate a flare gas recovery process with a gas sweetening process used in oil and gas refining. A flare gas recovery system includes a primary gas sweetening unit and a liquid-driven ejector in continuous fluid communication with the primary gas sweetening unit. The ejector includes an inlet configured to receive a motive fluid including a regenerable amine solvent in a lean state from the primary gas sweetening unit, a gas inlet configured to receive a suction fluid including a gas, and a fluid outlet configured to either directly or indirectly discharge to the primary gas sweetening unit a two-phase fluid including a mixture of the suction fluid and the amine solvent in a rich state.

An absorbent for selective removal of hydrogen sulfide 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 flare gas recovery system includes a primary gas sweetening unit; and a liquid-driven ejector in continuous fluid communication with the primary gas sweetening unit. The ejector includes an inlet configured to receive a motive fluid including a regenerable amine solvent in a rich state from the primary gas sweetening unit; a gas inlet configured to receive a suction fluid including a gas; and a fluid outlet configured to either directly or indirectly discharge to the primary gas sweetening unit a two-phase fluid including a mixture of the suction fluid and the amine solvent in a rich state.