The present invention provides a carbon dioxide absorbent comprising a primary amine and a dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether. The carbon dioxide absorbent according to the present invention has an excellent carbon dioxide absorptivity, absorption rate and regeneration property.

A compound of the general formula (I)

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in which R.sub.1, R.sub.2 and R.sub.3 are independently selected from C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; each R.sub.4 is independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; each R.sub.5 is independently selected from hydrogen, C.sub.1-4-alkyl and C.sub.1-4-hydroxyalkyl; m is 2, 3, 4 or 5; n is 2, 3, 4 or 5; and o is an integer from 0 to 10. A preferred compound of the formula (I) is 2-(2-tert-butylaminoethoxy)ethylamine. Absorbents comprising a compound of the formula (I) have rapid absorption of carbon dioxide from fluid streams and are also suitable for processes for the simultaneous removal of H.sub.2S and CO.sub.2, where given H.sub.2S limits have to be observed but complete removal of CO.sub.2 is not required.

A process for removal of mercury in a gas dehydration system comprising (a) adding a complexing agent to a recirculated glycol solvent as part of the glycol solution feed prior to or at the dehydration liquid contactor and recirculating continuously with the glycol solvent, (b) selectively reacting the complexing agent with mercury in the wet natural gas to remove the mercury from the dry natural gas product, (c) and feeding the rich glycol with the complexing agent to a regenerator and continuously regenerating.

The present invention relates to a dehydration composition and method of use thereof for drying gas streams, in particular natural gas streams, wherein the dehydration composition comprises a (a) glycol and (b) an additive selected so as to increase the viscosity, surface tension, and/or specific gravity of the dehydration composition. Said dehydration composition and method results in the reduction of solvent loss during the dehydration step in a gas dehydration unit.

A method for cleaning a contaminated solvent used to treat a gas stream, for example a contaminated glycol or a contaminated amine stream, by vacuum evaporation using a mechanically-maintained horizontally-orientated thin film evaporator, where the contaminant material is recovered from the thin film in solvent-free form, as either a heavy organic material or as free flowing salts.

A plant comprises a feed gas source, H2S removal unit, first absorber and a second, pressure reduction stages, first and second heat exchangers, stripping unit, and a conduit. The H2S removal unit selectively removes H2S from a feed gas from the feed gas source to produce an H2S depleted feed gas. The first absorber and the second absorber remove CO2 from the H2S depleted feed gas using a semi-lean and an ultralean solvent to produce a product gas and a rich solvent. The plurality of pressure reduction stages generates a cooled flashed solvent. The first heat exchanger and the second heat exchanger use the cooled flashed solvent to cool the H2S depleted feed gas and the semi-lean solvent. The stripping unit strips the flashed solvent with dried air to produce the ultralean solvent, and the conduit combines a portion of the ultralean solvent with the H2S depleted feed gas.

A plant includes a pretreatment unit for H2S removal and air dehydration, and at least two absorbers that receive a feed gas at a pressure of at least 300 psig with variable CO2 content (e.g., between 5 to 60 mol %), wherein the feed gas is scrubbed in the absorbers with an ultralean and a semi-lean physical solvent, respectively, at low temperatures to at least partially remove the CO2 from the feed gas. Such configurations produces a low CO2 dry treated gas and a H2S-free CO2 for sequestration while advantageously providing cooling by expansion of the rich solvent that cools the semi-lean solvent and the feed gas, wherein an ultralean solvent is produced by stripping using dry air.

There is provided herein a method for processing a gas comprising one or more impurity, the method comprising a) treating the gas with an impurity lean gas treating composition comprising i) a foam control agent comprising a polyalkylene glycol made by the polymerization of one or more alkylene oxide monomer initiated by a polyhydric compound having a functionality equal to or greater than 3 and ii) a gas treating agent and b) forming an impurity loaded gas treating composition. Preferably the gas is refinery gas or natural gas.

A carbon dioxide absorbent composition is described, including (i) a liquid, nonaqueous silicon-based material, functionalized with one or more groups that either reversibly react with CO.sub.2 or have a high-affinity for CO.sub.2, and (ii) a hydroxy-containing solvent that is capable of dissolving both the silicon-based material and a reaction product of the silicon-based material and CO.sub.2. The absorbent may be utilized in methods to reduce carbon dioxide in an exhaust gas, and finds particular utility in power plants.

Methods of reducing the water content of a wet gas are presented. In one case, the method includes exposing the gas to an amine-terminated branched polymer solvent to remove a substantial portion of the water from the wet gas, exposing the diluted solvent to carbon dioxide to phase separate the solvent from the water, and regenerating the solvent for reuse by desorbing the carbon dioxide by the application of heat. In another case, the method includes exposing the gas to a cloud-point glycol solvent to remove a substantial portion of the water from the wet gas, heating the diluted solvent to above a cloud point temperature for the solvent so as to create a phase separation of the solvent from the water so as to regenerate the solvent for reuse, and directing the regenerated solvent to a new supply of wet gas for water reduction.