Embodiments of the invention are directed to methods, processes, and systems for safely and reliably purifying hydrogen from a gas mixture containing hydrogen and oxygen.

Described and represented is a glycol drying system with at least one wet glycol collection container and/or at least one glycol collection line to collect moist glycol, with at least one heating device to heat the moist glycol in the at least one wet glycol collection container and/or in the at least one glycol collection line and with a membrane separation system to separate the water from the heated, moist glycol. In order to reduce the operating costs, without having to accept disproportionate investment costs, it is provided that at least one flash gas vent is provided to remove flash gas driven out when the moist glycol is heated before separating the water in the membrane separation system and in that at least one combustion chamber provided to combust the flash gas and to provide heat for the heating device.

Solvent absorption processes for separating components of an impure feed gas are disclosed. The processes involve two stages of gas purification. The acid gases including hydrogen sulfide, carbon dioxide and other sulfur compounds are simultaneously removed from the feed gas by contact with a physical solvent in two stages. The subject matter disclosed provides improved processes to reduce the operating costs of the system.

The invention pertains to processes for separating water from air. The processes may employ using an LCST solution with or without subsequent reverse osmosis, nanofiltration, or ultrafiltration.

An absorbent for the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide, wherein the absorbent contains an aqueous solution, comprising: a) an amine or a mixture of amines of the general formula (I) wherein R.sup.1 is C.sub.1-C.sub.5-alkyl; R.sup.2 is C.sub.1-C.sub.5-alkyl; R.sup.3 is selected from hydrogen and C.sub.1-C.sub.5-alkyl; x is an integer from 2 to 10; and b) an ether or a mixture of ethers of the general formula (II): R.sup.4[OCH.sub.2CH.sub.2].sub.yOH; wherein R.sup.4 is C.sub.1-C.sub.5-alkyl; and y is an integer from 2 to 10; wherein R.sup.1 and R.sup.4 are identical; wherein the mass ratio of b) to a) is from 0.08 to 0.5. The absorbent is suitable for the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide. The absorbent has a reduced tendency for phase separation at temperatures falling within the usual range of regeneration temperatures for the aqueous amine mixtures and is easily obtainable.

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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.

Disclosed is a carbon dioxide absorbent and a carbon dioxide separation method using the same that greatly reduces energy consumption due to a small amount of latent heat required in regeneration of absorbents, enhances CO.sub.2 absorption rate, undergoes almost no thermal denaturation even at high temperatures while absorbing carbon dioxide, and results in a considerable reduction of the cost associated with absorption of carbon dioxide.

Treatment of streams containing hydrogen and/or hydrocarbons, and in one non-limiting embodiment refinery distillates, with alkyl carbonates, such as dimethylcarbonate, alone or together with at least one solvent results in reduction or removal of hydrogen sulfide (H.sub.2S) that is present to give easily removed alkyl sulfides and/or mercaptans. In one non-limiting embodiment, the treatment converts the original hydrogen sulfide into alkyl sulfides and/or mercaptans that can be extracted from the stream with caustic solutions, mercaptan scavengers, solid absorbents such as clay or activated carbon or liquid absorbents such as amine-aldehyde condensates and/or aqueous aldehydes.

A process is provided for treating a hydrocarbon gas stream comprising sending the hydrocarbon gas stream to a membrane unit to be separated into a residue stream and a permeate gas stream; then sending the permeate gas stream with or without undergoing compression to a solvent absorption unit to remove carbon dioxide and other impurities; and recovering a treated gas.

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 (i) a glycol, (ii) a borate compound, (iii) an alkali metal carboxylate, and (iv) an additional glycol different than (i), and/or (v) an additional additive selected from an alkanolamine, a phosphate acid or salt compound, a sweetening agent, a low temperature viscosity improver, a corrosion inhibitor, an antifoaming agent, or mixtures thereof.