Regeneration of an aqueous solution from an acid gas absorption process by multistage flashing and stripping

Gary T. Rochelle
Journal Title
Journal ISSN
Volume Title
United States Patent and Trademark Office

An acid gas such as carbon dioxide, hydrogen sulfide, or a mixture thereof is removed from gaseous streams using aqueous absorption and stripping processes. By replacing the conventional stripper used to regenerate the aqueous solvent and capture the acid gas with a multipressure stripper (51) that combines acid gas compression with stripping, less energy is consumed. The multipressure stripper is a multistage flash (52, 55, 59) in which the total vapor flow from each stage is compressed and fed to the bottom of the previous flash stage at a higher pressure. In this process, the heat in the water content of the vapor exiting each stage is utilized at a higher pressure in the previous stage. The described stripping process generates the acid gas at a higher pressure without operating the stripper at a higher temperature, thereby reducing the energy consumption of the system.