METHOD AND APPARATUS FOR DESULFURIZING AND DENITRATING EXHAUST GAS IN DRY SYSTEM

摘要

PURPOSE:To desulfurize and denitrate an exhaust gas effectively using a dry system by a simple apparatus, by a method wherein the exhaust gas is desulfurized in a gas phase and the temp. range of a denitrating catalyst in subsequently denitrating said gas in a gas phase is specified. CONSTITUTION:An exhaust gas 6 containing SOx and NOx enters a gas phase desulfurizing vessel 2 through a dust collector 1 and water and ammonia are introduced into the desulfurizing vessel 2 to desulfurize the exhaust gas at a controlled temp. in a gas phase. The desulfurized gas enters a denitrating vessel 3 along with excessive ammonia and passed through an activated carbon catalyst layer 5 preliminarily impregnated with ammonium sulfite and dried at a temp. of 100-200 deg.C to remove NOx in the exhaust gas and the denitrated gas is discharged from a pipe 9. Washing water of the desulfurizing vessel 2 and the denitrating vessel 3 enters a dyproduct treating installation 4 and oxidized by air supplied from a pipe 16 and calcium carbonate supplied from the pipe 16 to be converted to ammonia and calcium sulfate by double decomposition. This ammonis is recirculated to the desulfurizing vessel 2 by a pipe 11.