Design And Performance Research Of Mechanical Vapor Recompression And Crystallization System For Concentration Saline Phenol Wastewater

Having the maximum yield and maximum usage amount of pesticide in the world,China is a large country in the degree of producing and using pesticide.According to statistics,the ratio of pesticides production and waste water discharging is 1:100.The large amount of pesticide waste water discharges to the nature,which result in serious environment problems.The major approach to dispose the pesticide waste water is to reduce and optimize emission,and particularly,enhance the treatment.Because there are many species of pesticides,it is difficult to conduct different measures to the waste water.In this paper,the waste water with salt and phenol was taken as the research object.The basic physical property analysis,thermal physical properties test,crystallization kinetics study,basic test and pilot test were processed to research and develop the equipment which is suitable for the evaporation and crystallization for this waste water.The density,heat conductivity coefficient,specific heat and viscosity in different temperature and different concentration were tested to realize basic physical properties of the waste water.Through simulating the evaporation and crystallization test,the conclusion can be drew as follows:Saturated boiling point at atmospheric is rising about 9.5?,while it will decrease at decompression pressure;the solubility at 90? is 38.614;Crystallization kinetics index is i=1.790.Pilot plant test was conducted after basic detection and underbrush in order to ensure the application in industry.The grain size,the nucleation rate,growth rate,such as test data can be gained through analyzing on the crystal in different layer in crystallizer,and find the best working point.Oslo crystallizer was used in pilot plant test,and the best location was about 1/3?1/4 from the bottom of the crystallizer sedimentation layer,where has the optimum crystal through comparative analysis.MVR compressor technology was adopted through contrasting multi-effect in order to optimization of process.Under the condition of the evaporation temperature of 75? to 90?,compared to the compressor power,water cooling,evaporation crystallization device parameters such as the total energy consumption,total area,the evaporation temperature was determined to 90 ?.In order to improve the energy utilization,and use the heat of the condensed water,crystal slurry output,mother liquor reflux such as,multistage plate preheater and plate type evaporator was used in the design of Equipment.Separator,condensing water vapor liquid separating unit adopts my patent structure,to improve the operation efficiency.The equipment running well by adjusting the crystallization circulation and the heat partition between evaporation and crystallization in engineering application,and the average particle size of crystallization salt from waste water was 0.4 mm,COD content in condensate water is less than 50 PPM.The development of the design needs to be done aim at different waste water due to all the members of the opposite sex of Pesticide wastewater.