PRODUCTION OF AMMONIUM NITRITE

摘要

PURPOSE:To enhance NH3NO2 yeild and reduce the NOx content of exhaust gas by adding auxiliary NOx gas contg. more eNO2 to absorption tower outlet gas of each stage to regulate NOx in each mixed gas to a specific molar ratio of eNO/eNO2 and contacting the gas to an ammonium carbonate soln. of a specific temp. CONSTITUTION:Auxiliary NOx gas having the molar ratio of eNO/eNO2 about 0.05-0.8 is added from each auxiliary gas feed line 4a-4c to residual NOx gas A passed through a gas-liquid contact zone, i.e. liquid cylindrical part 9 and packed bed part 10 in each absorption tower 2a-2d of multistage absorption tower 2 to regulate the molar ratio of eNO/eNO2 in mixed gas B to about 0.9-5. Gas B is supplied to the next stage tower in succession and contacted to a circulating absorbing soln. of -10-10 deg.C contg. ammonium carbonate mixed with an absorbing soln. of the upper stage in each tower 2a-2d. NOx gas is supplied to first tower 2a through line 1, and an ammonium carbonate soln. is supplied from fresh ammonium carbonate soln. supply line 7.