An absorbent composition that is useful in the selective removal of hydrogen sulfide relative to carbon dioxide from gaseous mixtures that comprise both hydrogen sulfide and carbon dioxide and the use thereof. The absorbent composition includes an amine mixture of an amination reaction product of tert-butylamine with a polydispersed polyethylene glycol (PEG) mixture having an average molecular weight within a certain specified range of molecular weights. The amination reaction product may also comprise a first sterically hindered amine and a second sterically hindered amine. The absorbent composition, preferably, includes an organic co-solvent, such as a sulfone compound. A method is also provided for improving the operation of certain gas absorption processes by utilizing the absorbent composition.

An alkaline aqueous ferric iron salt solution is disclosed. Generally, the alkaline aqueous ferric iron salt solution comprises ferric ions (Fe.sup.3+), potassium ions (K.sup.+), carbonate ions (CO.sub.3.sup.2−), bicarbonate ions (HCO.sub.3.sup.−), hydroxide ions (OH.sup.−), optionally nitrate ions (NO.sub.3.sup.−). Further, a molar ratio of the potassium ions to the ferric ions is generally at least 5.0. The ferric iron is complexed with carbonate, bicarbonate or both to form a water-soluble complex that is anionic in nature and highly soluble in the alkaline aqueous ferric iron salt solution at pH above 8.5, and a pH of the alkaline aqueous ferric iron salt solution is at least 8.5.

A method and apparatus for processing a hydrocarbon gas stream including sulfurous components and carbon dioxide. The hydrocarbon gas stream is separated into a sweetened gas stream and an acid gas stream. The acid gas stream and an air stream, enriched with oxygen such that the air stream comprises between 22% and 100% oxygen, are combusted in a sulfur recovery unit to separate the acid gas stream into a liquid stream of elemental sulfur and a tail gas stream comprising acid gas impurities. The tail gas stream and an air flow are sub-stoichiometrically combusted to produce an outlet stream comprising hydrogen sulfide and carbon monoxide. The outlet stream is hydrogenated to convert sulfur species to a gaseous catalytic output stream comprising hydrogen sulfide. Water is removed from the gaseous catalytic output stream to produce a partially-dehydrated acid gas stream, which is pressurized and injected into a subsurface reservoir.

Processes and systems for oxygen-enhanced Claus carbon dioxide recovery are disclosed. Oxygen is fed to a sulfur recovery unit instead of air. The tail gas is fed to a tail gas treatment unit which produces a treated tail gas, and the treated tail gas is processed in a carbon dioxide recovery unit to produce a carbon dioxide product. A method for retrofitting an existing sulfur recovery unit and tail gas treatment unit so as to recover the carbon dioxide product is also disclosed.

The present disclosure relates to processes for desulfurizing hydrocarbon feedstocks. The processes may include introducing a feedstock comprising hydrogen sulfide to an absorber comprising a metal chelate to form a reduced metal chelate. The processes may further include introducing the reduced metal chelate to a photobioreactor comprising a phototrophic bacterium. The present disclosure also relates to apparatuses for desulfurizing hydrocarbon feedstock. An apparatus may include and absorber and a photobioreactor fluidly connected to the absorber. The photobioreactor may be an anaerobic vessel with a light source.

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.

A method for providing a fuel includes providing biogas from a plurality of biogas sources, the biogas from each biogas source produced in a process comprising filling a vessel with raw biogas or partially purified biogas to a pressure of at least 1500 psig and transporting the filled vessel to a centralized processing facility by vehicle. A fuel is produced in a fuel production process that includes feeding the biogas transported to the centralized processing facility to a biogas upgrading system that is configured to provide a carbon dioxide removed from the biogas. The removed carbon dioxide is provided for transport by vehicle and/or pipeline and/or sequestered to offset greenhouse gas emissions attributed to compressing the biogas for transport.

Methods for removing reduced sulfur compounds, such as hydrogen sulfide, from fluids employing a ferric iron salt that exhibits unusually high solubility in aqueous, alkaline solutions and has strong affinity for capture and oxidation of reduced sulfur compounds. Alkaline aqueous ferric iron salt and solutions thereof useful for removing reduced sulfur compounds from fluids and various methods of production of such salts and solutions. In addition, methods of regenerating the alkaline aqueous ferric iron salt solutions after capture of hydrogen sulfide or other reduced sulfur compounds, generally by exposure to oxygen in air. The alkali metal carbonate salt preferably comprises potassium carbonate and/or potassium bicarbonate. The alkaline aqueous ferric iron salt solutions generally comprise ferric ions, potassium ions, carbonate ions, and bicarbonate ions, optionally with one or more organic additives. In addition, aqueous-soluble, ferric iron salts and ferric iron containing solids prepared by removal of aqueous medium from solutions herein.

Disclosed is a process for regenerating a hybrid solvent used to remove contaminants from a fluid stream and to provide an improved yield of purified fluid. Said process comprises a purification unit (12) and at least one regeneration unit (40) wherein make-up water (72) is added to the regenerated lean hybrid solvent (55) prior to reuse in the first purification unit and no water is recycled into the regeneration unit.

Disclosed is a process for regenerating a hybrid solvent used to remove contaminants from a fluid stream and to provide an improved yield of purified fluid. Said process comprises at least one purification unit (12) and at least one regeneration unit (40) wherein condensed water 62 from the regeneration unit is recycled back into the purification unit and none of the condensed water is reintroduced into the regeneration unit.