Design Of Denitrification Project Of 2×65 T/h CFB Heating Boilers

In Our country's energy structure,oil and gas is relatively small,but coal is more abundant,so coal is the main energy.While the national industrial level is increasing,the urbanization rate is gradually accelerating,the energy demand also will be greatly improved.However,coal combustion has brought haze,SO₂,NO_x and other air pollution problems to the environment.NO_x not only can cause photochemical smog pollution and destruction of the ozone layer,but also nitric acid rain.At present,in the following of SO₂ and dust,the comprehensive management about controlingg of NO_x in flue gas has also become the focus of the work.The design of denitrification project is about 2×65 t/h circulating fluidized bed?CFB?heating boilers in Xin'an Town,Shihezi City.The original NO_x content of the flue gas is about 350 mg/Nm³,which does not accord with the requirement of the national boiler flue gas emission standard 300 mg/Nm³,nor does it comply with the government's control requirements for total pollutant emissions.Therefore,the project of denitrification design not only can comply with the national environmental laws and regulations,but also is the contribution of ecological civilization in Xinjiang.The main research and study on the denitrification of the circulating fluidized bed?CFB?heating boilers are as following:?1?Boilers operation profile analysis and the establishment of denitrification target.Even if the CFB boiler can adapt to a variety kinds of coal,load regulation is strong,and NO_x generation is less,but when the local environmental regulations are more stringent,or project owner contract of denitrification rate requirements is high,it may not meet the NO_x emission requirements.In order to achieve ultra-low emission standards and the total pollutant emissions control targets,the design requirements for the final NO_x emission concentration is not more than 100 mg/Nm³ when working conditions are greater than 60% load.?2?Demonstration and selection of boiler denitrification process.According to technical and economic factors,from SCR,SNCR,SNCR-SCR combined technology to choose and demonstrate.Since the CFB boiler window temperature condition is both suitable for the high temperature reaction of the reducing agent with NO_x,and it is possible to avoid the generation of additional NO_x by side reaction.what's more,SNCR is also a cost-saving and safer technology.In the choice of reducing agent,taking into account the safety and the owner's capacity,the final choice is urea.?3?Denitrification process design and equipment selection.Denitrification process is as following: the solid urea as needed in the dissolved tank is configured as a suitable concentration of the solution,then filtered through the filter into the storage tank by the pump.In order to keep the denitrification stable,it is necessary to spray more of the reducing agent solution to meet the requirements of the fog field,so the urea solution is diluted.The urea solution in the tank and the demineralized water are mixed and diluted by a water pump and a static mixer,after that the mixture of urea solution are sent to a mixed storage tank.And then sent by the mixing station to the nozzle of the spray gun,through the nozzle of the atomization,the direct reduction reation between the reductant and NO_x in the boiler is achieve at last.In the equipment selection,design the selection of each module and parameter respectively.?4?Denitrification system analysis.This design can achieve 75% denitrification rate,when working conditions are greater than 60% load,the final emissions of NO_x in the flue gas concentration is not more than 100 mg/ Nm³,the total amount of pollutants decreased by about 882 t/a.During the operation,the environmental risk is small,and the control target of the expected design requirement and the total discharge of pollutants can be achieved.