Certain implementations of amine sweetening of flash gas are described. Flash gas including acid gas is flowed from a flash drum through a column section connected to the flash drum. A lean amine stream is flowed through the column section. The lean amine stream is configured to treat the acid gas flowed from the flash drum through the column section. A quantity of the lean amine stream flowed through the column section is controlled based, in part, on a rate at which the flash gas including the acid gas is flowed from the flash drum through the column section and a concentration of the acid gas in the flash gas.