Fractional condensation process was used to recover the permeate ethanol-water vapor downstream the pervaporation membrane under vacuum.The heat transfer and mass transfer behavior of the vacuum condensation dephlegmator was stressed.The effects of inlet vapor flow rate on the heat transfer coefficient and condensation behavior of the vacuum condensation dephlegmator were analyzed.When the inlet vapor flowing velocity was increased from 3.09 to 8.05 m/s,the heat transfer process was effectively intensified.The total heat transfer coefficient was increased from 37.06 to 145.27 W/(m2·K),with the vapor side condensing heat transfer coefficient also increasing from 55.81 to 544.60 W/(m2·K).At different flowing velocity,the proportion of thermal resistance in the heat transfer process varied.At low vapor flowing velocity,the vapor side thermal resistance was relatively high,reaching up to 82.99％.After the flow rate increased,the proportion of thermal resistance on the cooling medium side was increased,reaching up to 65.66％.With the increase in feed flowing velocity,the recovery proportion of ethanol-water vapor in the vacuum condensation dephlegmator was improved from 41.82％to 68.19％,with the ethanol recovery proportion increasing from 5.21％to 30.72％.The ethanol mass fraction in the first condensate was also increased from 3.45％to 10.66％.
关键词
渗透汽化/乙醇水蒸气/真空分馏/传质/传热
Key words
pervaporation/ethanol-water vapor/vacuum dephlegmator/mass transfer/heat transfer
维普
万方数据