Rubbish incinerator gas treatment - uses added hydrochloric acid gas at incineration to give improved mercury extraction at the washing stage

摘要

To treat the exhaust gas from an incinerator, especially a rubbish incinerator, hydrochloric acid gas is added to the incineration. The amount of added hydrochloric acid gas is controlled according to the hydrochloric acid gas content of the exhaust gas before washing, which is set so that it does not reach at least 50 mg/Nm3 before washing. An oxidn. agent is added to the washing soln. pref. hydrogen peroxide. USE/ADVANTAGE - The technique is for exhaust gases which contain sulphur dioxide, hydrochloric acid gas and mercury, esp. from rubbish incineration. The dust is extracted from the gas to be treated with an acid salt wash soln. and the mercury is pref. removed by sulphide pptn. from the washing soln. The method improves the mercury removal as it is converted into mercury chloride which can be washed out of the exhaust gas.