| 摘要 |
PURPOSE: To economically and highly efficiently desulfurize exhaust gas by measuring the concns. of NOx and NH3 in the exhaust gas after passed through a wet desulfurization equipment and controlling the amt. of NH3 being a desulfurizing agent to be added and the temp. of desulfurized exhaust gas containing NH3 to specific values. CONSTITUTION: The concns. of NOx and NH3 in the exhaust gas at the outlet of a wet desulfurization equipment are continuously measured by an NOx analyser 8 and an NH3 analyser 9 and the concn. signals are inputted to a regulator 10. In the regulator 10, the opening degree of a regulation valve 11 is adjusted to control the amt. of NH3 gas added from an NH3 adding line 7 so that the amt. of NH3 to the amt. of NOx in the exhaust gas becomes a set value within a range of 1 equivalent ratio or more, pref., 0.1-1 equivalent ratio. Next, exhaust gas containing NOx and NH3 is heated to a temp. range of 100-350 deg.C, pref., 200-350 deg.C developing the activity of a reductive denitration catalyst in a downstream heating device 12 to be sent to a reductive denitration reaction apparatus 13. By this constitution, efficient denitration is performed and a desulfurizing absorbing soln. 5 is adjusted to pH10 or more in a process discharging a part of the absorbing soln. 5 to the outside of the system and heated to recover NH3 as gas from the absorbing soln. 5 and this NH3 gas is used as a part of NH3 to be added. |
