Study On Near Zero Emission Technology For High Salinity Wastewater

High salinity wastewater is one of the extremely difficult to be treated in industrial wastewater.Its high salinity,salt variety,prone to make equipment fouling and corrosion,high organic pollutants concentration and difficult to deal with organic matter,makes its treatment a big problem in the field of environment protection at home.Therefore,exploring a kind of economic efficient near zero emission technology to treat high salinity wastewater is very necessary.Mechanical vapor recompression(MVR)technology is a kind of efficient near zero emissions technology.According to the characteristics of high salinity wastewater,this paper comes up with a new built-in MVR treatment process,study the working process of the MVR internal on the basis of the results of numerical simulation,and find a way to enhance heat transfer.In this dissertation,desulfurization wastewater was chosen as the model contaminant.It exploited a new kind of falling film heat exchanger that is the plate pendant-type thin-film heat exchanger,which heat exchange plates were made from plastic film.Under the condition of vacuum of 80 kPa,evaporation temperature of60?,temperature difference of 2.3?and differential pressure of 2kPa,it came up with a suitable MVR treatment process to deal with high salinity wastewater.On this basis,it analyzed the structure and characteristics of plate thin-film heat exchanger and the MVR energy-saving mechanism,and calculated material balance and heat balance in the MVR treatment process.In this paper,the plate pendant-type thin-film heat exchanger is mainly focused.The Gambit,Fluent and response surface methodology are used to analyze the MVR technology mechanism and find out the way of heat transfer enhancement.In this paper,it used the Gambit to build the two-dimensional geometry,utilized the Fluent to achieve the full port numerical simulation.When the plastic heat transfer film thickness was 0.07 mm,high salinity wastewater inlet temperature was 40? and its inlet flow was 0.6 m~3/h,the Fluent got the plate thin-film heat exchanger's flow field,velocity field,temperature field and pressure field.The paper analyzed the fluid flow and heat transfer process in the heat exchanger inner space,heat exchange membrane internal heat transfer process,discussed the working process of the MVR internal.The results were considered a potential and promising technology for heattransfer enhancement.The study used the response surface methodology and Fluent to optimize the heat transfer.To groups of process conditions that the plastic heat transfer film thicknesses were 0.04 mm,0.07 mm and 0.10 mm,high salinity wastewater inlet temperatures were 20?,40?and 60?,its inlet flows were 0.4 m~3/h,0.6 m~3/h and 0.8 m~3/h,respectively.Box-Behnken experiment design method arranged optimum proposals,and the Fluent calculates the proposals' response values.The best optimization result showed that the plastic heat transfer film's thickness was 0.04 mm,high salinity wastewater inlet temperature was 40?,its inlet flow was 0.59 m~3/h,respectively.MVR near zero emissions technology can get the desalination rate of more than99%,the recovery rate of 95%,the high salinity wastewater emissions is just 5%,it achieves high salinity wastewater reduction.