Characteristic Study On NO_x Reduction By Reducing Fuel Gas

It takes more and more attention to achieve clean emission of nitrogen oxides as more and more serious environment pollution and strict emission standards. Selective catalytic reduction (SCR) is the most widely used, mature and effective technology in the world. Because there is a big malpractice with NH3-SCR, CO, H2, CH4 and other fuel gas catalytic NOx reduction become a hot topic. But the presence of O2 in the flue gas will reduce NOx reduction rate, the rotary denitration reactor is proposed to separate the NOx and O2, which enhances the NOx reduction rate. But it still remains part of the reducing agent and NOx after rotary denitration reactor, which damage to the environment. Therefore, it is necessary to deal with this part of remnants reducing agent and NOx. Because the reducing agent and NOx can reacr directly at elevated temperature without catalyst, it should seek a high-temperature low-cost way to achieve deep purification.The NOx reduction ability of CO, H2, CH4 were studied in different atmosphere (strong oxidizing atmosphere, weak reducing and oxidizing atmosphere, reducing atmosphere) by using one-dimensional fixed-bed pilot plant. The influence of the fuel gas concentration, O2 concentration, temperature, initial NO concentration and residence time were also studied to identify reasonable atmosphere, then combined with the boiler combustion characteristics to find out concrete and feasible ways.Strong oxidizing atmosphere can be achieved in the boiler SNCR position.In SNCR position the flue gas has no denitration capacity and can produce secondary pollution because of the low temperatures and much oxygen remaining. Therefore, this approach is not feasible and it is necessary to improve the temperature of injected position and consume oxygen in the flue gas. Weak reducing and oxidizing atmosphere can be achieved in the boiler reburn position. In reburn position the flue gas can achieve a certain degree of denitration efficiency, but the gas consumption is relatively large and the overall economy is not high, it should be try to reduce gas consumption to improve the denitration efficiency. Strong reducing atmosphere can be achieved by duct denitration reactor arranged in a high temperature region. This approach is feasible due to achieving high denitration efficiency, reducing consumption reduced and improving the economy. However, the temperature of the reactor arrangement position is very high.The auxiliary ways by plasma and iron wire loaded in reactor were proposed to improve the denitration efficiency and lower the temperature.The feasibility of this ways were studied in different gas concentrations, O2 concentration, temperature. Then sum optimization techniques of non-catalytic NOx reduction in high temperature by reducing flue gas.Overall, the technology of iron wire loaded duct denitration reactor can be used as CO was the reducing gas. This reactor was arranged in a high temperature region of 600℃～800℃ and the iron wire is cheap.So this technology has high economy and can achieve a cheap and efficient NOx deep purification. The technology of duct denitration reactor by plasma can be used as CH4, H2 were the reducing gas. But this technology should still be improved.