【摘要】 研究了减压膜蒸馏浓缩人参提取物水溶液过程中的膜污染,考察了料液温度、膜两侧蒸汽压差和料液流速对膜污染的影响,分析了膜污染产生的原因,测定了浓缩过程中的膜阻力。结果表明:料液温度、膜两侧蒸汽压差和料液流速直接影响膜污染的程度,温度越高、蒸汽压差越大,膜污染越严重;当温度为338.15K时,运行5h后J/J0为0.3445,而温度为328.15K时J,/J0为0.835;当蒸汽压差为8.6kPa,运行5h后J/J0为0.3283,而当蒸汽压差为3.5kPa时J,/J0为0.8381。提高流速可以削弱浓差极化,更重要的是减轻膜污染现象的发生,当流速为60L.h-1时,运行5 h后J/J0为0.643 5,而流速为40L.h-1时J,/J0为0.3283。导致膜通量下降的主要原因是污染层阻力的增大,污染层阻力从所占总阻力8.02%增至23.92%;其次是浓差极化阻力,浓差极化阻力从所占总阻力9.25%增至12.2%,温差极化阻力影响较小。更多还原

【Abstract】 The membrane fouling during the vacuum membrane distillation process for Ginseng extracts aqueous solution concentration was investigated.The effect of operating temperature,the transmembrane vapor pressure difference,and flow rate on fouling were studied.The mechanism of fouling was investigated,the resistances in this process were determined.The results indicate that temperature,vapor pressure difference and flow rate directly influence the extent of fouling.The higher the feed temperature or the transmembrane vapor pressure difference is,the more serious the fouling is.When the feed temperature is 338.15 K,J/J0 is 0.3445,as the feed temperature of 328.15 K,J/J0 is 0.835.When the vapor pressure difference is 8.6 kPa,J/J0为0.3283,as the vapor pressure difference of 3.5 kPa,J/J0 is 0.8381.The increase of flow rate could decrease concentration polarization and membrane fouling.The reason of the flux decline is the increase of fouling resistance,and the concentration polarization resistance;the temperature polarization resistance can be neglected.更多还原