The separation characteristics of the PVA-CS (polyvinyl alcohol-chitosan) blended composite membrane for dehydration of ethanol-water mixture are examined. The relationships of flux and separation factor with the feed...The separation characteristics of the PVA-CS (polyvinyl alcohol-chitosan) blended composite membrane for dehydration of ethanol-water mixture are examined. The relationships of flux and separation factor with the feed concentration and operation temperature are established. Using this correlated equation, the continuous-flow pervaporation process about 500 kilolitres/year dehydrated ethanol is designed. The numbers of stage and reheater are calculated by stage-by-stage method for two kinds of cascades: one with equal membrane area and the other with 10℃ of temperature decrement per section. The results show that when the numbers of stage and reheater are the same, the cascade with 10℃ of temperature decrement has more advantages than that with equal membrane area. The influences of feed concentration and flow rate on the numbers of stage and reheater in the cascades are discussed.展开更多
A multi-layer mesoporous silicalite-1 membrane supported on commercially available porous alumina tubes was prepared by firstly dip-coating the tubes in silica colloid sol and then using a hydrothermal synthetic proce...A multi-layer mesoporous silicalite-1 membrane supported on commercially available porous alumina tubes was prepared by firstly dip-coating the tubes in silica colloid sol and then using a hydrothermal synthetic process.The mesoporous silicalite-1 membrane was further modified by grafting organosilane compounds with various alkyl chains length(C_nH_(2n+1)(CH_3)_2SiCl;n = 1,3,8,12 and 18).These hydrophobic silicalite-1 membranes containing silane coupling agents effectively removed ethanol from 3 wt.%,5 wt.%and 10 wt.%aqueous ethanol solutions by pervaporation over a temperature range of 303-323 K.The separation factor(a) of ethanol decreased as the ethanol content in the feed solution increased from 3%to 10%whereas the permeation flux(J) basically remained constant.Ethanol separation factors(a) of 7.90-22.24 with total fluxes(J) of 0.76-2.89 kg/(m^2h) were obtained by pervaporation at 3_3-323 K for ethanol feed composition of 3%-10%.展开更多
STAR丙烷脱氢工艺中深冷单元操作条件为3.20 MPa、-78℃,一方面反应产物中大量氢气随之压缩,另一方面需深度脱水,能耗高。可通过在产物预冷之后采用膜分离协同分离氢气、脱除水分并进行梯级压缩来改进该工艺。以35万t/a STAR工艺为例,引...STAR丙烷脱氢工艺中深冷单元操作条件为3.20 MPa、-78℃,一方面反应产物中大量氢气随之压缩,另一方面需深度脱水,能耗高。可通过在产物预冷之后采用膜分离协同分离氢气、脱除水分并进行梯级压缩来改进该工艺。以35万t/a STAR工艺为例,引入3 000 m^2的prism-Ⅱ膜单元进行改进后,渗余气含水质量分数降至0.9×10^-6,可省去干燥塔及解吸气压缩功190 k W;同时,梯级压缩功为6540 k W,较改进前节约310 k W;氢气摩尔分数由82.8%提高到95.9%,年产氢量约1.24亿m^3,新增经济效益9 070万元/a。展开更多
基金Supported by the National Natural Science Foundation of China(No.29836160) and Commission of Science & Technology of Zhejiang Province(No.924010,No.85-12-02-05).
文摘The separation characteristics of the PVA-CS (polyvinyl alcohol-chitosan) blended composite membrane for dehydration of ethanol-water mixture are examined. The relationships of flux and separation factor with the feed concentration and operation temperature are established. Using this correlated equation, the continuous-flow pervaporation process about 500 kilolitres/year dehydrated ethanol is designed. The numbers of stage and reheater are calculated by stage-by-stage method for two kinds of cascades: one with equal membrane area and the other with 10℃ of temperature decrement per section. The results show that when the numbers of stage and reheater are the same, the cascade with 10℃ of temperature decrement has more advantages than that with equal membrane area. The influences of feed concentration and flow rate on the numbers of stage and reheater in the cascades are discussed.
基金the National Natural Science Foundation of China under Grant No.50972103the Scientific Research Foundation for Returned Overseas Chinese Scholars,Ministry of Education of China
文摘A multi-layer mesoporous silicalite-1 membrane supported on commercially available porous alumina tubes was prepared by firstly dip-coating the tubes in silica colloid sol and then using a hydrothermal synthetic process.The mesoporous silicalite-1 membrane was further modified by grafting organosilane compounds with various alkyl chains length(C_nH_(2n+1)(CH_3)_2SiCl;n = 1,3,8,12 and 18).These hydrophobic silicalite-1 membranes containing silane coupling agents effectively removed ethanol from 3 wt.%,5 wt.%and 10 wt.%aqueous ethanol solutions by pervaporation over a temperature range of 303-323 K.The separation factor(a) of ethanol decreased as the ethanol content in the feed solution increased from 3%to 10%whereas the permeation flux(J) basically remained constant.Ethanol separation factors(a) of 7.90-22.24 with total fluxes(J) of 0.76-2.89 kg/(m^2h) were obtained by pervaporation at 3_3-323 K for ethanol feed composition of 3%-10%.
文摘STAR丙烷脱氢工艺中深冷单元操作条件为3.20 MPa、-78℃,一方面反应产物中大量氢气随之压缩,另一方面需深度脱水,能耗高。可通过在产物预冷之后采用膜分离协同分离氢气、脱除水分并进行梯级压缩来改进该工艺。以35万t/a STAR工艺为例,引入3 000 m^2的prism-Ⅱ膜单元进行改进后,渗余气含水质量分数降至0.9×10^-6,可省去干燥塔及解吸气压缩功190 k W;同时,梯级压缩功为6540 k W,较改进前节约310 k W;氢气摩尔分数由82.8%提高到95.9%,年产氢量约1.24亿m^3,新增经济效益9 070万元/a。
