Research And Application Of Low Temperature Circulating Oxidation And Denitration Technology In CFB Boiler

Circulating fluidized bed(CFB)boiler is the preferred combustion technology with high efficiency and low pollution in China.The commonly used NOx control technologies mainly include low nitrogen combustion technology,SCR,SNCR,redox denitration technology,etc.However,each NOx control technology has corresponding limitations and deficiencies.Especially after the implementation of ultra-low emission standard,many problems have been exposed in its operation,and it is urgent to develop supplementary denitration control technology.In China,with the wide application of semi dry desulfurization technology,its supporting COA cyclic oxidation absorption denitration technology is also gradually popularized and applied.Many engineering examples show that COA denitration technology has its specific advantages.In the technology of desulfurization and denitration,COA denitration technology has great application prospects.The paper analyzes causes and main influencing factors of NOx in CFB boiler,carries out the research and application of circulating oxidation absorption denitration technology,and analyzes a thermal power plant in combination with the application status of oxidation absorption denitration technology.For the COA Denitration Process configured for 2×75t/h coal-fired CFB boiler,carry out the evaluation of engineering application and theoretical research effect,and complete the research on COA denitration technology and application of the coal-fired power plant.The adaptability of coa Denitration Process to flue gas composition of CFB boiler and the main problems in operation are analyzed from the perspective of key equipment selection and calculation.At the same time,through the combination of theoretical analysis and CFD simulation,the design optimization is carried out from the aspects of simplifying the structure of the injection device and improving the denitration efficiency,and relevant experiments are carried out.According to the actual operation of the power plant,the maximum load,design load and whether there is open air circulation under 70% load are selected to compare the operation effects before and after optimization.The main conclusions are as follows:By reducing the number of ozone injection holes to improve the flow rate of the injection holes,the uniformity of ozone concentration distribution can be improved,and the NOx removal efficiency,ozone and absorbent utilization of the optimized ozone injection device can be improved to varying degrees.It shows that how to make the ozone more evenly distributed in the flue and more fully mixed with the flue gas is one of the key factors to improve the denitration efficiency of Co A and reduce the ozone supply and absorbent consumption.At the same time,the analysis shows that the optimization scheme has significantly improved the denitration stability compared with the original scheme.In addition,this paper also compares the liquid phase + gas phase simultaneous oxidation experiment,and comes to the conclusion that the joint experimental scheme is limited in improving the denitration efficiency.In this paper,through theoretical analysis,process demonstration,combined with the synchronous comparative analysis of CFD simulation and engineering examples,it is proved that improving the ozone distribution uniformity by improving the ozone injection device is feasible to improve the denitration efficiency and denitration stability,which has a certain reference significance.