Various illustrative embodiments of a system and process for recovering high-quality biomethane and carbon dioxide product streams from biogas sources and utilizing or sequestering the product streams are provided. The system and process synergistically yield a biomethane product which meets gas pipeline quality specifications and a carbon dioxide product of a quality and form that allows for its transport and sequestration or utilization and reduction in greenhouse gas emissions. The system and process result in improved access to gas pipelines for products, an improvement in the carbon intensity rating of the methane fuel, and improvements in generation of credits related to reductions in emissions of greenhouse gases.

There is an absorbent mixture usable for the removal of sour gases from gas mixtures. The mixture has at least one organic base having a pK.sub.b (in water) less than or equal to 3.2; at least one alcoholic solvent of general formula R(OH).sub.n having a boiling temperature above or equal to 100° C. at ambient pressure, wherein R is a linear or branched saturated alkyl group having a number of carbon atoms between 2 and 20 and n is a whole number varying between 1 and 20; an aprotic polar solvent having a dielectric constant ε at 25° C. greater than or equal to 30, a viscosity μ at 25° C. less than or equal to 14 cP, preferably less than or equal to 12 cP; and a boiling temperature at normal pressure equal to or above 130° C. There is also a process for the removal of sour gases using the absorbent mixture.

One variation of a method for carbon sequestration includes: mixing ambient air including carbon dioxide and secondary gases with a working fluid to generate a first mixture; conveying the first mixture through a compressor to pressurize the first mixture from a first pressure to a second pressure greater than the first pressure to promote absorption of carbon dioxide into the working fluid; depositing the first mixture in a high-pressure vessel to generate an exhaust stream of secondary gases and a second mixture including carbon dioxide dissolved in the working fluid; conveying the second mixture through a turbine configured to extract energy and reduce pressure of the second mixture, from the second pressure to the first pressure, to promote desorption of carbon dioxide from the working fluid; transferring the second mixture into the low-pressure vessel; and releasing carbon dioxide, desorbed from the working fluid, from the low-pressure vessel for collection.

The present invention relates to a process for regenerating a rich MEG aqueous solution (100), recovering a maximum amount of MEG while at the same time removing the carboxylic acid salts, including: a) vacuum evaporation of the solution (100) in a unit (1000); b) optional precipitation in a tank (1002) of the inorganic salts of a portion (105) of the liquid residue enriched in MEG and in salts (104) obtained from a); c) removal of the precipitated inorganic salts in a solid/liquid separation unit (1003); d) sending all or part (114) of the liquid effluent (112) obtained from c) into a separation unit (1004) different from the unit (1000) to form, notably, an MEG stream depleted in carboxylic acid salts or in carboxylic acids (115); e) recycling of said stream (115) into step a).

This exhaust gas processing equipment is provided with an exhaust line through which exhaust gas discharged from a boiler circulates, a carbon dioxide recovering device for recovering carbon dioxide included in the exhaust gas, and an exhaust gas heating device provided downstream of the carbon dioxide recovering device to heat the exhaust gas. The carbon dioxide recovering device includes a first medium line through which a first medium circulates, and a second medium line through which a second medium higher in temperature than the first medium circulates. The exhaust gas heating device includes a first heating unit for heating the exhaust gas by means of heat exchange with the first medium, and a second heating unit for heating the exhaust gas passing through the first heating unit even more by heat exchange with the second medium.

Provided is a carbon dioxide recovery system including: an absorption tower; a regeneration tower that takes in an absorbing solution that has absorbed carbon dioxide at the absorption tower, and separates the carbon dioxide from the absorbing solution using regenerated steam to regenerate the absorbing solution; first supply piping that supplies the absorbing solution regenerated in the regeneration tower to the absorption tower; a reclaimer that takes in part of the absorbing solution regenerated in the regeneration tower to remove degraded material and supplies the absorbing solution from which the degraded material has been removed to the regeneration tower or the first supply piping; an in-line viscometer that measures a viscosity of the absorbing solution flowing through the first supply piping; and a controller that controls an amount of the absorbing solution processed by the reclaimer based on the viscosity measured by the in-line viscometer.

A carbon dioxide (CO.sub.2) capture and utilization system captures CO.sub.2 from flue gas and utilizes the same to enhance algae or cyanobacteria growth. The system generally comprises a CO.sub.2 capture unit and a utilization unit that is in fluid communication with the CO.sub.2 capture unit. The CO.sub.2 capture unit includes a membrane CO.sub.2 absorber that captures CO.sub.2 from incoming flue gas to produce a CO.sub.2-rich solvent. The utilization unit processes the CO.sub.2-rich solvent to produce a product stream that includes CO.sub.2 and NH.sub.3 in a predetermined CO.sub.2:NH.sub.3 ratio. The product stream is delivered to a cultivation subsystem of the utilization of the unit including one or more species of algae or cyanobacteria. A method for capturing and utilizing CO.sub.2 is also provided herein.

A solvent system for the removal of acid gases from mixed gas streams is provided. Also provided is a process for removing acid gases from mixed gas streams using the disclosed solvent systems. The solvent systems may be utilized within a gas processing system.

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.

In one embodiment, a carbon dioxide capturing system includes an absorber to absorb CO2 from first gas into lean liquid, and produce rich liquid that is the lean liquid absorbing the CO2 and second gas that is the first gas removing the CO2, and a regenerator to separate third gas including the CO2 from the rich liquid flowing from the absorber, and provide the lean liquid and the third gas. The system further includes a flowmeter to measure a flow rate of the third gas, a liquid level gauge to measure a liquid level of the lean liquid and/or the rich liquid, and a controller to regulate a quantity of heat energy supplied to the regenerator based on the flow rate of the third gas, and regulate a total amount of the lean liquid and the rich liquid in the system based on the liquid level.