Study On Parameter Optimization Of Flue Gas Desulfurization And Denitrification Dedusting Of CWS Boiler

With the progress and development of the country,the risk of environmental pollution is also gradually increasing,regional pollution problems are becoming more and more serious,industrial activities as one of the main sources of air pollution,therefore,the country widely attaches import,ance to it.The state environmental protection administration has proposed in the tenth five-year plan for national environmental protection that it should vigorously develop coal-water slurry technology.Based on the characteristics of coal-water slurry boiler flue gas,this paper analyzes the typical domestic desulfurization and denitrification processes,and by means of field test and flow field simulation,finds out the operation process improvement scheme of denitrification,desulfurization and dust removal devices of a coal-water slurry boiler flue gas for heating.Through the ammonia concentration,ammonia temperature,uniformity of flue gas,liquid-gas ratio of desulfurizer,separation efficiency of fog removal to optimize parameters,completely reached the heating coal-water slurry boiler flue gas emissions standards,mean:under the condition of 6%oxygen content,dust,sulfur dioxide,nitrogen oxides emissions concentration is not higher than 20,50,100 mg/Nm3.1.Optimization of denitration process1)By manually adjusting the air opening of each damper in the combustion area,the influence of the upper damper opening and the exhaust air flow rate on the nitrogen oxide production under different boiler loads was tested.The results show that when the NOx concentration in the reactor is reduced from 450 mg/m3 to 360 mg/m3,the reduction range is 20%,and the oxygen concentration in the combustion zone decreases.2)The influence of denitration temperature window on denitration efficiency was studied through field test.The results show that:when SNCR+SCR combined denitrification process is adopted,the working conditions are simulated2)The influence of denitrification temperature window on denitrification efficiency was studied by means of field working condition simulation.The results show that:when SNCR+SCR combined denitration process is adopted,the optimal temperature window of SNCR is 900-1000?,and the optimal temperature window of SCR is 320-400?.3)The effect of urea addition mode on nitrogen oxide content was investigated.The results show that the nitrogen oxide content in flue gas can be effectively reduced from 300mg/m3 to 250mg/m3 with a decrease of 16.7%.4)According to EPA-7E standard sampling,the distribution of nitrogen oxide and ammonia concentration,flue gas flow rate,and flue gas temperature in the flue gas denitration reactor at the end of the flue gas were tested by grid sampling.The results show that There is no guide plate,only by the disturbance of the heat exchange tube beam.2.Desulfurization and dust removal process optimization1)The effects of wet desulphurization on the pH value,liquid-gas ratio and pressure loss of desulphurization tower on the desulphurization efficiency were studied by the limit operation method.The results show that:the optimal control range of each parameter of desulfurization tower is:the pH of circulating liquid is controlled at 6.0-6.4,the liquid-gas ratio is maintained at 1.7-3.1,and the pressure loss of desulfurization tower is maintained at 1700-2000pa.2)By tracing the distribution of desulphurization fluid and analyzing the solid content of the droplet of the net flue gas at the outlet of the desulphurization tower,the defects of the original flue gas uniform distribution plate and corrugated plate demister were judged and the combination of the liquid in the pipe bundle of the desulphurization tower and the three-stage roof demister was found.The results show that:the sulfur dioxide and dust content of flue gas can meet the pollution factor control requirements of the national thermal power emission standard after replacing the liquid holding layer of the pipe bundle and roof defogging device.After optimization,the nitrogen oxide content of flue gas decreases from 450-500mg/Nm3 before denitration to 60-85mg/Nm3 within the range of 40-110%load variation of boiler.The overall denitration efficiency is more than 80%,SO2?50mg/Nm3,and dust?20mg/Nm3.All pollutant factors of flue gas can meet the national thermal power emission standard.