Design And Research Of Key Equipment On Acrylonitrile Wastewater Zero Discharge Process Based On MVR

Evaporator and steam compressor are key equipment on acrylonitrile wastewater zero discharge treatment process based on MVR.According to the characteristic of acrylonitrile wastewater and acrylonitrile wastewa-ter treatment process,falling-film evaporator and centrifugal steam compressor were chose.And flash-falling-film evaporator was designed.Based on the analysis of the influence factors of the evaporation efficiency,the CFD numerical simulation method was used to optimize the structure design of external flow distributor and liquid distributor.Opti-mal design of the variable-cross-section external flow distributor about flash-falling-film evaporator was studied.The design method of centrifu-gal compressor impeller,diffuser and volute and the key performa-nce factors are studied.The main results were as follows:(1)Compared with other structures,falling-film evaporator was more suitable as evaporator of acrylonitrile wastewater zero discharge treatment process.Based on Fluent numerical simulation method,extern-al flow distributor and liquid distributor on the performance of MVR evaporator was analyzed.There are two discoveries.The variable-cross-section external flow distributor with circular-arc transition on the fluid velocity distribution uniformity was better than the slotted type external flow distributor and the external flow distributor with circular-arc transi-tion.And The liquid distributor of tangential hole is more uniform and better than liquid distributor of radial hole.The film thickness is stable and uniform when the liquid level above the inlet of liquid distribut-or is 300 mm.(2)The inlet angle 9 = 0°?24°,the clearance of inner high end L =90?140mm,the distributor height H = 188-216mm of the variable-cross-section external flow distributor with circular-arc transition on the fluid flow distribution uniformity about shellside of evaporator were studied.According to the flow distribution uniformity of longitudinal section and inlet section in shellside,it was better when 0=15°,L=110 mm,H =212 mm.(3)The centrifugal steam compressor was chosen as compressor of acrylonitrile wastewater zero discharge treatment process.The installation angle of blade outlet,impeller flow coefficient and b2/D2 ratio affect the impeller outer diameter and affecting the selection of diffuser.The relationship of the inlet/outlet pressure ratio of impeller and the total pressure ratio tends to be proportional.The inlet/outlet pressure ratio of impeller tends to constant with the increase of inlet temperature or the velocity of inlet and outlet.The relationship of the inlet/outlet pressure ratio of diffuser and inlet temperature or the total pressure ratio tends to be proportional.The inlet/outlet pressure ratio of diffuser tends to constant with the increase of the velocity of inlet and outlet.The structure selection and optimal design method of MVR evapora-teor on acrylonitrile wastewater zero discharge treatment process was mainly studied.The design of MVR steam compressor was studied preliminarily.Based on the results of simulation analysis,it is necessary to verify the reliability of them in engineering practice.