INDUSTRIAL DEMONSTRATION ON NOX REMOVAL BY GAS REBURNING IN A 50MW_E TANGENTIAL PULVERIZING COAL-FIRED BOILER

摘要

More than 70% of NOx in air comes from various coal burning processes. Among NOx removal technologies, gas-reburning technology have been proven to be an available technology by all industrial demonstrations in USA and Europe. To identify the feasibility of NOx removal with gas reburning technology for low rank coal in China, an industrial demonstration test of NOx removal with the gas reburning technology was carried in a 220t/h tangential pulverizing coal-fired boiler in JiangYou power plant from 2002 to 2004. In the test, reburning gas and burn out air were arranged at the front and rear walls of the furnace in a creative way. It was the first time in the world for such an arrangement method of reburning gas and burn out air were applied. The relationship of NOx removal efficiency with the nature gas flow rate, the Oxygen content in the furnace and operating methods of ball mills (or the Third Air) were tested. During the test, the change of the temperature of superheat steam and the furnace temperature were measured. The industrial demonstration test results showed: the NOx removal efficiency may reach at 50% and NOx discharge content may be as lower as 200 mgm~3 when the heat value of burning coal was about 18MJ/kg (LHV). Some factors, which affected the efficiency of NOx removal, were discussed in this paper.