Denitration Experiment And Numerical Simulation In The Sodium Acetate Industrial Waste Salt Furnace

As a typical industrial waste salt(IWS),the waste salt of pesticide industry has the characteristics of large output,complex chemical composition,high toxicity,difficult biodegradable substances and serious pollution.Incineration is considered to be a highly promising treatment of industrial waste salt.The industrial waste salt of sodium acetate produced in the production process of dicyandiamide pesticide can be injected into the coal-fired boiler as an additive for in-furnace flue gas desulfurization and denitrification.This will not only make the sodium acetate industrial waste salt harmless and reduce the treatment,but also help control the coal-fired pollutants.This article takes sodium acetate industrial waste salt as the object.Based on the denitrification of SNCR,the denitration in the furnace under the condition of sodium salt and simultaneous desulfurization and denitrification experiment of high temperature flue gaswas carried out by using the high-temperature carrying flow reaction device.On-site test of industrial waste salt solution treatment was carried out on a 75 t/h circulating fluidized bed boiler of Lingyunhai Thermal Power Plant.The Fluent software was used to simulate the SNCR denitration process.The main conclusions are presented as follows:(1)Dissolving sodium acetate and sodium acetate industrial waste salt into ammonia water to prepare a composite denitration agent.The effects of sodium acetate and sodium acetate industrial waste salts,reaction temperature,sodium content in flue gas,residence time and ammonia-nitrogen molar ratio(NSR)on denitrification characteristics were studied by using a high-temperature entrained flow reactor.The results indicate that:With the increase of reaction temperature,the denitrification efficiency of ammonia SNCR and composite denitration agent generally increased first and then decreased.The industrial waste salt of sodium acetate and sodium acetate can increase the window temperature of the ammonia SNCR by about 100?.At temperatures below 900?,sodium acetate and sodium acetate industrial waste salts have a significant effect on ammonia SNCR.The denitration efficiency of pure sodium acetate and industrial waste salt is low.When the sodium content is 150?mol/mol,the denitration efficiency is only 16.8%and 16.0%.Denitrification efficiency of the composite denitrizer increases with the increase of sodium content,and can reach 80.4%and 79.3%when the sodium content is 150 ?mol/mol.Denitration efficiency increases with the increase of residence time.When the residence time exceeds 1 s,denitration efficiency is maintained at about 74%.When the residence time is 0.5-1.0 s,desulfurization efficiency of the composite desulfurization denitration agent increases with the increase of residence time.When the residence time exceeds 1.0 s,denitrification efficiency of the composite denitrizer decreases.(2)Preparation of composite desulfurization denitration agent by adding calcium-magnesium-based additive to composite denitration agent.The effects of additive type,reaction temperature,Ca/S ratio and residence time on desulfurization and denitrification efficiency of composite desulfurization and denitrification agent were studied by using high temperature entrained flow reactor.The results indicate that:The denitration efficiency of the composite desulfurization denitration agent obtained by adding organic calcium(CA,CMA)on the basis of the composite denitration agent is almost the same as that of the composite denitration agent.At 1000?,the desulfurization efficiency of the composite desulfurization denitration agent with calcium magnesium acetate and calcium acetate can reach 66.1%and 65.3%.Denitration efficiency of the composite desulfurization denitration agent with fly ash/calcium carbonate is reduced by about 10%at each temperature.However,for desulfurization efficiency,there is an approximately 2%increase at each temperature.In the range of Ca/S ratio less than 2.5,the desulfurization efficiency of the composite desulfurization denitration agent is obviously increased.When the Ca/S ratio continues to increase,the rate of desulfurization efficiency is obviously slowed down.When the residence time is 0.5-1.0 s,desulfurization efficiency of the composite desulfurization denitration agent increases with the increase of residence time.When the residence time exceeds 1.0 s,desulfurization efficiency decreases.(3)The on-site test of industrial waste salt solution treatment was carried out,mainly to study the effects of industrial waste salt solution injection on boiler operation,boiler efficiency,NO pollutant emission and ash characteristics.The results indicate that:The injection of industrial waste salt solution has no significant impact on the normal operation of the boiler,and the power plant emissions can still meet the national atmospheric emission standards.It can be seen from the XRF test analysis of fly ash and ash that the sodium salt enters the fly ash and ash,and more sodium salt enters the ash.(4)Numerical simulation of SNCR denitration process based on Fluent software.The results indicate that:With the increase of reaction temperature,the denitration efficiency increased first and then decreased,and the optimum denitration efficiency was obtained at 950?.As the NSR increases,the denitration efficiency increases.When the NSR is greater than 1,the denitration efficiency under the experimental conditions is slower,and the increase under the simulated conditions is larger.