Electrostatic Technology In The Removal Of Aerosol In Ammonia Desulphurization

Recently,increasing of frequency,scope and intensity of haze has been impacting surrounding environment.Thus,more and more local governments connect power network and additional units with flue gas emission standards and propose near zero emission standard where dust concentration is required no more than 5mg/m3,in order to implement the guide lines for the state's effort to control smog.Conventional ammonia flue gas desulfurization technique has problems like aerosol plume trailing,drifting entrainment of ammonium sulfate,corrosion,crystallization and fouling,which hinder the system from long term running.The desulfurization system should be adjusted and improved in the process of absorption,oxidation,ammonia addition,fog removal,and rinsing ect.,combining with the requirements of ultra-clean emission,to solve the problems with ammonia desulfurization.Firstly,the inlet flue gas is added with moisture to lower its temperature,solving the issue of dry wet interface crystallization,and the system can be equipped with rinsing devices,which can be put into use when the humidification system is out of order or under maintenance;secondly,absorption system can be advanced by careful choice and arrangement of spray nozzles,which can achieve 150% spray coverage,meanwhile absorption system can be applied with graded cycle absorption and let each cycle to supplement slurry to the cycle before it,which can make sure that latter cycle contains slurry with lower concentration to control the emission of aerosol and particulate matter;thirdly,ammonia addition and oxidation in the system are modified to make newly added ammonia to form a steady state in slurry pool as soon as possible,decreasing the potential aerosol generation in flue gas,and the oxidation aperture and layout are rearranged to oxidize formed sulfite into sulfate which is more stable;additionally,smog,mist and fine aerosol can be comprehensively controlled through technologies such as the adjustment of flow field of outlet wet electrostatic precipitator,epipolar change and upgrade of power supply.After the adjustment and improvement of the processes,outlet dust concentrations were tested by third party,with readings ranging from 1.8 to 2.6mg/m3,which achieved the design requirements and solved problems of PM2.5,aerosol plume trailing,SO3 excessive acid mist and entrainment of ammonium sulfate,and completely eliminate tail gas smoke situation and stack rain,complying with the requirements of energy conservation.The device was operated six month continuously without any problems of crystallization,fouling,corrosion or leaking.The system runs stably and can run long term operation,and is especially suitable for petrochemical and iron and steel enterprises with ammonia resource.