A control process and apparatus provide feed forward control of stoichiometric proportions of hydrogen sulfide and ammonia to a thermal oxidizer and an ammonia scrubber, respectively. To account for unmeasured or uncalculated sulfur feed to the thermal oxidizer, a feed back measurement of sulfur dioxide and ammonia concentration is used to correct the flow rate of hydrogen sulfide to the thermal oxidizer and/or ammonia to the ammonia scrubber.

A process and a plant for purifying a crude gas stream containing sulfur components and hydrocarbons by gas scrubbing using a scrubbing medium which is selective for sulfur components in an absorption column. Heavy hydrocarbons and heavy mercaptans are removed from the crude gas in a lower section of the absorption column and the resulting, loaded scrubbing medium stream is fed separately from the other loaded scrubbing medium streams to a hot regeneration column. A vapor stream enriched in water, hydrocarbons and sulfur components is obtained as overhead product from the hot regeneration column and this stream is cooled to below its dew point and is separated in a gas-liquid-liquid phase separation apparatus. The resulting, organic liquid phase contains heavy hydrocarbons and heavy mercaptans and can thus be discharged from the process or the plant, as a result of which accumulation thereof in the scrubbing medium is prevented.

Methods of controlling hydrogen sulfide concentration of a biogas occupying an anaerobic membrane bioreactor (AnMBR) containing a submerged membrane are disclosed herein. Methods of controlling dissolved sulfide concentration of a mixed liquor within the AnMBR are disclosed. The methods include directing wastewater containing sulfur and a chemical oxygen demand (COD) to an AnMBR, withdrawing at least a fraction of the biogas from the AnMBR, directing a pre-determined amount of the withdrawn biogas to a scrubber, directing a remainder of the withdrawn biogas to a gas distributor, and directing the scrubbed biogas to the AnMBR. Systems for treating wastewater having sulfur and COD are disclosed. The systems include an AnMBR, a scouring gas closed loop, a scrubber, and a control mechanism for directing biogas to the scrubber and to a gas distributor. Methods of retrofitting a system for treating wastewater having sulfur and COD are disclosed.

A method to purify a hydrocarbon gas with hydrogen sulfide as an impurity comprises: (a) charging a chamber with a bed of active-metal carbide of a predetermined mesh-size range; (b) conducting the hydrocarbon gas through the bed of active-metal carbide, forming additional hydrocarbon gas by reaction of the active-metal carbide and the hydrogen sulfide; and (c) filtering from the chamber the hydrocarbon gas without the hydrogen sulfide.

Disclosed is an absorbent containing an amine for absorption of an acid gas in a biogas, and a biogas purification system using the same.

A method for capturing carbon dioxide includes contacting a carbon dioxide lean gas mixture with water. One or more acid gas impurities may pass from the carbon dioxide lean gas mixture to the water to form a gas mixture and an aqueous effluent. The gas mixture is passed to a pressure swing adsorption system or a temperature swing adsorption system to increase a concentration of carbon dioxide in the gas mixture to form a carbon dioxide enriched gas mixture. The carbon dioxide enriched gas mixture is contacted with the aqueous effluent in a carbon dioxide scrubber. Carbon dioxide passes from the carbon dioxide enriched gas mixture to the aqueous effluent to form a stripped gas and acid gas enriched water. The acid gas enriched water is passed to a reactive rock formation. The one or more acid gas impurities and carbon dioxide are mineralized and permanently sequestered.

A process and apparatus for managing hydrogen sulfide in a refinery is provided. In the process, a hydrogen sulfide stream from said refinery is fed to a sulfur recovery unit to produce sulfur and a sulfur compound stream or to a thermal oxidizer. The sulfur compound stream and the hydrogen sulfide stream are then thermally oxidized to produce a sulfur oxide stream. The sulfur oxide stream is then reacted with an ammonia stream. In aspect, the product of the reaction can be a fertilizer. The ammonia stream can be obtained from stripping the hydrogen sulfide stream.

A process for operating a reforming system by operating a reforming section containing a plurality of reactors, wherein each of the plurality of reactors containing a reforming catalyst capable of catalyzing the conversion of at least a portion of the hydrocarbons in a treated hydrocarbon stream into a reactor effluent comprising aromatic hydrocarbons, and operating a sulfur guard bed (SGB) to remove sulfur and sulfur-containing hydrocarbons from a hydrocarbon feed to provide the treated hydrocarbon stream, where the SGB contains at least a layer of a SGB catalyst comprising the same catalyst as the reforming catalyst, and where each reactor of the plurality of reactors within the reforming section may be operated at a higher operating temperature than an operating temperature of the SGB. A system for carrying out the process is also provided.

Capture of hydrogen sulfide from a gas mixture may be accomplished using an aqueous solution comprising an amine. Certain sterically hindered amines may selectively form a reaction product with hydrogen sulfide under kinetically controlled contacting conditions and afford a light phase and a heavy phase above a critical solution temperature, wherein the hydrogen sulfide may be present in either phase. Upon separation of the light phase from the heavy phase, processing of one of the phases may take place to remove hydrogen sulfide therefrom. Recycling of the amine to an absorber tower may then take place to promote capture of additional hydrogen sulfide.

There is disclosed a modular anaerobic digestion point-of-waste to renewable energy system. The system is directed to a modular and scalable anaerobic digestion system for point-of-waste use. The System includes a pretreatment process for removing inhibitory nutrients from a feedstock, an in-treatment process for providing clean renewable energy and a post-treatment process for further providing clean renewable energy for subsequent use. The System includes a leaching bed; a liquids tank; a mixing tank; an anaerobic digester reactor; a precipitation tank; a stripping tank; a hydrogen sulfide scrubber; a water remover; a gas bladder; a dewaterer; and a flare system.