SYSTEM AND PROCESS FOR TRAPPING SULFUR DIOXIDE AND CARBON DIOXIDE BY AMMONIA ABSORPTION AT ATMOSPHERIC PRESSURE

摘要

Disclosed are a system and a process for trapping sulfur dioxide and carbon dioxide by ammonia absorption at atmospheric pressure. The system comprises a dilute aqueous ammonia solution supply unit (1), a sulfur dioxide absorption unit (7), and a carbon dioxide absorption unit (8). The process comprises the steps of: feeding flue gas, after dust is removed and temperature is reduced, into a carbon dioxide absorption column (71), wherein the dilute aqueous ammonia solution contacts the flue gas counter-currently and reacts with the flue gas in a gas-liquid two-phase reaction and absorbs sulfur dioxide to yield an aqueous solution of ammonium sulfate; sending the aqueous solution of ammonium sulfate, after its temperature is reduced, to a sulfur dioxide crystallizing tank (73) for crystallization, and then carrying out solid-liquid separation in a ammonium sulfate product centrifuge (74); feeding the flue gas, after sulfur dioxide is removed, into a carbon dioxide absorption column (81), wherein the dilute aqueous ammonia solution contacts the flue gas counter-currently and reacts with the flue gas in a gas-liquid two-phase reaction and absorbs carbon dioxide to yield an aqueous solution of ammonium bicarbonate; discharging the flue gas through a pipe on top of the carbon dioxide absorption column (81) after sulfur dioxide and carbon dioxide are removed; and feeding the aqueous solution of ammonium sulfate, after temperature is reduced, to a carbon dioxide crystallizing tank (83) for crystallization, and then carrying out solid-liquid separation in a ammonium bicarbonate product centrifuge (84).