Process and apparatus for removal of nitrogen oxides, sulfur oxides and mercury from off gas through oxidization

Abstract

Provided is a process for integrating treatment of off gas through NOremoval, SOremoval and mercury removal, which could avoid high energy consumption resulting from high temperature required for the reaction, and a corresponding apparatus thereof. The process comprises the splitting of the off gas to a sub-stream off gas flow line as a carrier for the oxidizing agent. In the sub-stream line, a heating chamber is set for the decomposition of the oxidizing agent to form free radicals (when hydrogen peroxide is used, the free radicals formed are hydroxy and peroxy hydroxy free radicals) having stronger oxidative capacity than the original oxidants used, these free radicals carried in the sub-stream off gas are then combined with the unheated mainstream off gas, and react with the reducible contents such as NO, SOand mercury vapor in the off gas to generate NO, SOand mercury ions with higher oxidation state, wherein all the acidic products and mercury ions will be removed in the subsequent gas scrubbing device. The process and apparatus enable substantial reduction of energy required for oxidization and effective removal of NOand SOas well as the reducible heavy metals such as metallic mercury, owing to only a portion of flue gas used as the carrier for the oxidizing and ionizing of the oxidative agents.