空气中微量有机气体的膜分离研究
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摘要
气体膜分离技术脱除空气中微量有机物对于保护环境具有十分重要的意义。投资少、能耗低、使用方便和操作弹性大等是这项技术的最大特点和优势。本文采用硅橡胶膜去除空气中微量的十氢萘，并设计实验流程以及膜组件的放大，将最终的出口浓度降到对人体无害的25ppm以下。
本文首先进行了膜材料筛选的研究。由溶涨胀实验可知，与CA、PVA、PVB、PVDF这几种膜材料相比硅橡胶膜对十氢萘的溶胀程度很大，能达到100％以上。CA、PVA、PVB、PVDF在20分钟时达溶胀平衡；而硅橡胶在60分钟时仍未达平衡，但溶胀度已达0.55；PVDF溶胀程度非常小，几乎没有吸收。50℃时，十氢萘在硅橡胶中的扩散系数D二1.74X10—2 mm2、溶解系数S二1.15、渗透系数P二2.001X10-／mm；c。因此，在研究中我们采用PVDF做支撑膜，以硅橡胶作为分离的选择层材料的复合膜。
其次，制备了以PAN、PS、PVDF为底膜的平板膜(有效膜面积为15.9cm2，硅橡胶膜厚度为0.45mm)进行分离实验。以PVDF为例，在50℃、一个入口大气压、真空度0.05atm、流速为1.5L／min、分离时间为2hr情况下，入口浓度为986.2ppm，而出口处浓度以降至572.3ppm，降幅达41.97％，分离系数口二288，分离效果较好，单位膜面积每天处理量可达6.996kg／m2·day。
再次，以PVDF、PS为支撑层，研制了硅橡胶为分离层的中空纤维膜进行分离实验。入口空气中的十氢萘浓度随入口压力的增加增加，分离系数随入口压力的增加减小；入口浓度随入口温度的增加增加，分离系数随入口温度的增加增加；入口浓度随入口流速的增加减小，分离系数随入口流速的增加减小；下游真空度降低时，入口浓度基本不变，分离系数随真空度的降低而减小。以PS为支撑层，硅橡胶为分离层的中空纤维膜为例，在流速为1.1m’，恤时，入口浓度为71.2ppm，而出口处浓度高达39.6ppm，降幅达44.32％，分离系数口二426，单位膜面积每天处理量二14.052g／m2·day。
最后，进行了级联计算，以底膜为PVDF的硅橡胶平板膜为例，在入口空气中十氢萘浓度为1231.4ppm时，若出口空气中十氢萘含量低于25ppm时，假设口、 刀(P，／F)都是常数则级联数为7，膜面积为0.0113m2：若夕是常量，口为变量，当级联数为14时，出口浓度仍然高达108ppm。
Using gas membrane technology to separate the microscale organic substance from the air is very important to the environment protection. This technology has so many advantages, such as few investment > little energy consume, convenience operation. In this paper, PVDF-SR composite membrane is prepared to remove the decahydronaphthalene (DHT) from the air. Membrane model and the experiment circuit are designed to reduce the exit concentration under 25ppm.
First, the separation membrane materials are chosen from CA,PVA,PVB>PVDF and SR. From swelling experiments, the swelling degree of DHT in SR is larger than that of the other materials, such as CA> PVA, PVB, PVDR it can reach to 100%. In CA -. PVA , PVB % PVDF, the time of swelling experiments that used to come to balance is about 20 min. but after 60 min DHT in SR does not come to swelling balance as SD (swelling degree) is 0.55. In PVDF. the swelling degree is very small. At 50 癈. D (diffusion coefficient) of DHT in SR is 1.74X 10~~mrrr, S (solution coefficient) is 1.15. P (permeation coefficient) is 2.001 X 10"2mm2. Therefore. PVDF and SR are selected as support layer and separation layer, respectively.
Then, the plane membrane, which using PAN, PS, PVDF as support layer (effective area is 15.9cm~, the thickness of SR is 0.45mm). are prepared to separate the DHT from air. As PVDF-SR composite membrane, (at 50癈.the entry pressure is one atm. the vacuum degree is 0.05atm. the flow rate is 1.5L min.the separating time is 2hr.) the entry concentration is 986.2ppm. however the exit concentration is down to 572.3ppm. descending degree is 41.97%. The separation factor ( a ) is 288. The capacity of unit membrane area reaches 6.996kg/nr ?day.
Third, the hollow fiber, which using PVDF, PS as support layer and SR as separation layer, is prepared. From the separation results, the entry concentration increases with the rise of entry pressure and the temperature, but decreases with the increment of flow rate. The separation factor ( a) decreases with the increment of flow rate and the entry pressure, but increases with the temperature. As PS-SR composite membrane, (at 50癈.the entry pressure is one atm. the vacuum degree is lOmmHg. the flow rate is l.lnr.the separating time is Ihr.) the entry concentration is 71.2ppm. however the exit concentration is down to 39.6ppm. descending degree is 44.32%. The separation factor( a ) is 426. the capacity of unit membrane area is 14.052g/m: ?day.
Last, cascade calculation is studied. As PVDF-SR composite membrane, as the
entry concentration is 1231.4ppm. the exit concentration of last unit should under
25ppm. If a , are both constant, then the cascade number is 7; if/? is constant.
a is variable, then the exit concentration only reach 108ppm as the cascade
connection is 14. more cascade number are needed.
本文首先进行了膜材料筛选的研究。由溶涨胀实验可知，与CA、PVA、PVB、PVDF这几种膜材料相比硅橡胶膜对十氢萘的溶胀程度很大，能达到100％以上。CA、PVA、PVB、PVDF在20分钟时达溶胀平衡；而硅橡胶在60分钟时仍未达平衡，但溶胀度已达0.55；PVDF溶胀程度非常小，几乎没有吸收。50℃时，十氢萘在硅橡胶中的扩散系数D二1.74X10—2 mm2、溶解系数S二1.15、渗透系数P二2.001X10-／mm；c。因此，在研究中我们采用PVDF做支撑膜，以硅橡胶作为分离的选择层材料的复合膜。
其次，制备了以PAN、PS、PVDF为底膜的平板膜(有效膜面积为15.9cm2，硅橡胶膜厚度为0.45mm)进行分离实验。以PVDF为例，在50℃、一个入口大气压、真空度0.05atm、流速为1.5L／min、分离时间为2hr情况下，入口浓度为986.2ppm，而出口处浓度以降至572.3ppm，降幅达41.97％，分离系数口二288，分离效果较好，单位膜面积每天处理量可达6.996kg／m2·day。
再次，以PVDF、PS为支撑层，研制了硅橡胶为分离层的中空纤维膜进行分离实验。入口空气中的十氢萘浓度随入口压力的增加增加，分离系数随入口压力的增加减小；入口浓度随入口温度的增加增加，分离系数随入口温度的增加增加；入口浓度随入口流速的增加减小，分离系数随入口流速的增加减小；下游真空度降低时，入口浓度基本不变，分离系数随真空度的降低而减小。以PS为支撑层，硅橡胶为分离层的中空纤维膜为例，在流速为1.1m’，恤时，入口浓度为71.2ppm，而出口处浓度高达39.6ppm，降幅达44.32％，分离系数口二426，单位膜面积每天处理量二14.052g／m2·day。
最后，进行了级联计算，以底膜为PVDF的硅橡胶平板膜为例，在入口空气中十氢萘浓度为1231.4ppm时，若出口空气中十氢萘含量低于25ppm时，假设口、 刀(P，／F)都是常数则级联数为7，膜面积为0.0113m2：若夕是常量，口为变量，当级联数为14时，出口浓度仍然高达108ppm。
Using gas membrane technology to separate the microscale organic substance from the air is very important to the environment protection. This technology has so many advantages, such as few investment > little energy consume, convenience operation. In this paper, PVDF-SR composite membrane is prepared to remove the decahydronaphthalene (DHT) from the air. Membrane model and the experiment circuit are designed to reduce the exit concentration under 25ppm.
First, the separation membrane materials are chosen from CA,PVA,PVB>PVDF and SR. From swelling experiments, the swelling degree of DHT in SR is larger than that of the other materials, such as CA> PVA, PVB, PVDR it can reach to 100%. In CA -. PVA , PVB % PVDF, the time of swelling experiments that used to come to balance is about 20 min. but after 60 min DHT in SR does not come to swelling balance as SD (swelling degree) is 0.55. In PVDF. the swelling degree is very small. At 50 癈. D (diffusion coefficient) of DHT in SR is 1.74X 10~~mrrr, S (solution coefficient) is 1.15. P (permeation coefficient) is 2.001 X 10"2mm2. Therefore. PVDF and SR are selected as support layer and separation layer, respectively.
Then, the plane membrane, which using PAN, PS, PVDF as support layer (effective area is 15.9cm~, the thickness of SR is 0.45mm). are prepared to separate the DHT from air. As PVDF-SR composite membrane, (at 50癈.the entry pressure is one atm. the vacuum degree is 0.05atm. the flow rate is 1.5L min.the separating time is 2hr.) the entry concentration is 986.2ppm. however the exit concentration is down to 572.3ppm. descending degree is 41.97%. The separation factor ( a ) is 288. The capacity of unit membrane area reaches 6.996kg/nr ?day.
Third, the hollow fiber, which using PVDF, PS as support layer and SR as separation layer, is prepared. From the separation results, the entry concentration increases with the rise of entry pressure and the temperature, but decreases with the increment of flow rate. The separation factor ( a) decreases with the increment of flow rate and the entry pressure, but increases with the temperature. As PS-SR composite membrane, (at 50癈.the entry pressure is one atm. the vacuum degree is lOmmHg. the flow rate is l.lnr.the separating time is Ihr.) the entry concentration is 71.2ppm. however the exit concentration is down to 39.6ppm. descending degree is 44.32%. The separation factor( a ) is 426. the capacity of unit membrane area is 14.052g/m: ?day.
Last, cascade calculation is studied. As PVDF-SR composite membrane, as the
entry concentration is 1231.4ppm. the exit concentration of last unit should under
25ppm. If a , are both constant, then the cascade number is 7; if/? is constant.
a is variable, then the exit concentration only reach 108ppm as the cascade
connection is 14. more cascade number are needed.
引文
1．周琪、张俐娜，气体分离膜研究进展，化学通报，2001 (1)：18～25
2.Arruebo, M., Coronas, J., Men(?)ndez, M., Santamaria, J., Separation of hydrocarbons from natural gas using silicalite membranes, Separation and Purification Technology, 2001 (10): 275～286
3.Robeson, L. M., Polymer membranes for gas separation, Current Opinion in Solid State & Materials Science, 1999 (12): 549～552
4．刘丽、邓麦村、袁权，气体分离膜研究和应用新进展，现代化工，2000 (1)：16～21
5.Pandey Pratibha, Chauhan, R.S., Membranes for gas separation, Progress in Polymer Science, 2001 (8): 853～893
6．林建章，气体膜分离器的应用和研究，辽宁化工，1989 (1)：52～55
7．廖勇、杭献功，普里森膜分离器提纯重整氢气，炼油设计，1996 (1)：14～16
8．董子丰，氮氢膜分离器，大氮肥，1991 (6)：470～473
9．孙振国、张明全，国产中空纤维N2-H2膜分离装置的应用，化学世界，1990 (5)：229～231
10．甄寒菲、王志，用于分离CO2的高分子膜，高分子材料科学与工程，1999，(6)：29～31
11．刘茉娥等，膜分离技术，化学工业出版社，北京：1998．P90
12．祈喜旺、陈翠仙等，聚酰亚胺气体分离膜，膜科学与技术，1996 (2)：1～7
13.Dhingra, Sukhtej. S.,Marand, Eva.,Mixed gas transport study through polymeric membranes, Journal of Membrane Science, 1998 (4): 45～63
14.L(?)dtke, O., Behling, R.-D., Ohlrogge, K., Concentration polarization in gas permeation, Journal of Membrane Science, 1998 (8): 145～157
15 朱长乐，膜分离技术在气体分离中的研究和应用，浙江化工，1995，26 (2)：3～6
16 吴志坚、吴宏，气体分离陶瓷膜研究进展，材料导报，1999 (10)：34～35
17 蒋柏泉，钯—银合金膜分离氢气的研究，化学工程，1996 (3)：48～52
18 高从阶，膜技术在石化工业中的应用浅谈，膜科学与技术，1998，(2)：1～2
19 余立新、霍中心，膜分离技术在石油化工中的应用，石油化工设计，1997，(2)：49～52
20 郑捷，膜分离法提取合成氨弛放气中的氢及其应用．陕西化工，1997 (2)：5～10
21 作者无，利用变压吸附气体分离技术从合成氨弛放气中回收氢气，煤气化技术通讯，2001，(1)：17～19
22 董子丰、赵勇，气体膜分离技术在合成氨联醇工艺中的应用，化肥工业，1995，(6)：17-20
23 Wile,F,P.,丁帮明，从炼厂气体中分离并回收氢气，石化译文，1997，(1)：25～27
24 Spillman,R.W.,Economics of gas separation membranes.Chemical Engineering Process,1989 (6):41～62
25 Scott,M.E,Houston,C,D.Membrane H_2/CO ratio adjustment.In:AIChE National Meeting.Houston,TX:April 1,1987
26 蒋国梁、徐仁贤、陈华，膜分离法与深冷法联合用于催化裂化干气的氢烃分离．石油炼制与化工．1995，26 (1)：26～30
27 董子丰，气体膜分离技术在石油工业中的应用，膜科学与技术，2000，(3)：38～43，49
28 Fritzsche,A.K.,Narayan,R.S.,Gas separations by membrane systems,Chemical Economy & Engineering Reviews,1987,19 (205):19～31
29 龙晓达、龙玲，膜分离技术在天然气净化中的应用现状．天然气工业，1993，13 (1)：100～105
30 阎勇，膜分离技术在有机废气处理中的应用．现代化工，1998 (11)：19～22
31 闫勇，有机废气中VOC的回收方法，化工环保，1997 (1)：34～38
32 Ohlrogge, K., Wind, J. and Behling, R.-D., Off-gas purification by means of membrane vapor separation systems, Sep. Sci. and Technol. 1995(30):1625～1638
33 Feng, X., Sourirajan, S., Tezel, F. H., Matsuura, T. and Farnand, B. A.,Separation of volatile organic compound/nitrogen mixtures by polymeric membranes, Ind. Eng. Chem. Res., 1993 (32):533～539
34 Baker, R. W., Simmons, V. L., Kaschemekat, J.and Wijmans, J. G., Membrane systems for VOC recovery from air streams, Filtration & Separation, 1994 (5):231～235
35 Ludgrada, B., Krzysztof, W., Marek, T., Aleksandra, J.-C., Cost analysis for the removal of volatile organic compounds from air using hybird systems: membrane separation/condensation versus membrane separation/combustion, Chem. Eng. and Proce., 1999 (38): 273～279
36 Sohn, W.-I., Ryu, D.-H., Oh, S.-J. and Koo, J.-K., A study on the development of composite membranes for the separation of organic vapors, Journal of Membrane Science, 2000(175): 163～170
37 张林、陈欢林、柴红，挥发性有机物废气膜法脱除工艺开发进展，(化工环保)，2002年待发表
38 胡宏纹主编，有机化学(第二版)，高等教育出版社，1990
39 蔡智鸣，关于十氢萘的顺反异构，大学化学，1997(2)：52～53
40 冯骏材，关于环几烷构象教学的探索，大学化学，1996(2)：23～25
41 Wang, B.G., Yamaguchi, T., Nakao, S-i., Journal of Polymer Science: Part B:Polymer Physics, 2000(38): 171～181
42 van de Witte, P., Dijkstra, P. J., van den Berg, J. W. A. and Feijen, J., Phase separation processes in polymer solutions in relation to membrane formation,Journal of Membrane Science, 1996, (1): 1～31
43 潘岚、周志军、刘茉娥，渗透汽化膜材料的选择，高分子材料科学与工程，1997(5)：138～142。
2.Arruebo, M., Coronas, J., Men(?)ndez, M., Santamaria, J., Separation of hydrocarbons from natural gas using silicalite membranes, Separation and Purification Technology, 2001 (10): 275～286
3.Robeson, L. M., Polymer membranes for gas separation, Current Opinion in Solid State & Materials Science, 1999 (12): 549～552
4．刘丽、邓麦村、袁权，气体分离膜研究和应用新进展，现代化工，2000 (1)：16～21
5.Pandey Pratibha, Chauhan, R.S., Membranes for gas separation, Progress in Polymer Science, 2001 (8): 853～893
6．林建章，气体膜分离器的应用和研究，辽宁化工，1989 (1)：52～55
7．廖勇、杭献功，普里森膜分离器提纯重整氢气，炼油设计，1996 (1)：14～16
8．董子丰，氮氢膜分离器，大氮肥，1991 (6)：470～473
9．孙振国、张明全，国产中空纤维N2-H2膜分离装置的应用，化学世界，1990 (5)：229～231
10．甄寒菲、王志，用于分离CO2的高分子膜，高分子材料科学与工程，1999，(6)：29～31
11．刘茉娥等，膜分离技术，化学工业出版社，北京：1998．P90
12．祈喜旺、陈翠仙等，聚酰亚胺气体分离膜，膜科学与技术，1996 (2)：1～7
13.Dhingra, Sukhtej. S.,Marand, Eva.,Mixed gas transport study through polymeric membranes, Journal of Membrane Science, 1998 (4): 45～63
14.L(?)dtke, O., Behling, R.-D., Ohlrogge, K., Concentration polarization in gas permeation, Journal of Membrane Science, 1998 (8): 145～157
15 朱长乐，膜分离技术在气体分离中的研究和应用，浙江化工，1995，26 (2)：3～6
16 吴志坚、吴宏，气体分离陶瓷膜研究进展，材料导报，1999 (10)：34～35
17 蒋柏泉，钯—银合金膜分离氢气的研究，化学工程，1996 (3)：48～52
18 高从阶，膜技术在石化工业中的应用浅谈，膜科学与技术，1998，(2)：1～2
19 余立新、霍中心，膜分离技术在石油化工中的应用，石油化工设计，1997，(2)：49～52
20 郑捷，膜分离法提取合成氨弛放气中的氢及其应用．陕西化工，1997 (2)：5～10
21 作者无，利用变压吸附气体分离技术从合成氨弛放气中回收氢气，煤气化技术通讯，2001，(1)：17～19
22 董子丰、赵勇，气体膜分离技术在合成氨联醇工艺中的应用，化肥工业，1995，(6)：17-20
23 Wile,F,P.,丁帮明，从炼厂气体中分离并回收氢气，石化译文，1997，(1)：25～27
24 Spillman,R.W.,Economics of gas separation membranes.Chemical Engineering Process,1989 (6):41～62
25 Scott,M.E,Houston,C,D.Membrane H_2/CO ratio adjustment.In:AIChE National Meeting.Houston,TX:April 1,1987
26 蒋国梁、徐仁贤、陈华，膜分离法与深冷法联合用于催化裂化干气的氢烃分离．石油炼制与化工．1995，26 (1)：26～30
27 董子丰，气体膜分离技术在石油工业中的应用，膜科学与技术，2000，(3)：38～43，49
28 Fritzsche,A.K.,Narayan,R.S.,Gas separations by membrane systems,Chemical Economy & Engineering Reviews,1987,19 (205):19～31
29 龙晓达、龙玲，膜分离技术在天然气净化中的应用现状．天然气工业，1993，13 (1)：100～105
30 阎勇，膜分离技术在有机废气处理中的应用．现代化工，1998 (11)：19～22
31 闫勇，有机废气中VOC的回收方法，化工环保，1997 (1)：34～38
32 Ohlrogge, K., Wind, J. and Behling, R.-D., Off-gas purification by means of membrane vapor separation systems, Sep. Sci. and Technol. 1995(30):1625～1638
33 Feng, X., Sourirajan, S., Tezel, F. H., Matsuura, T. and Farnand, B. A.,Separation of volatile organic compound/nitrogen mixtures by polymeric membranes, Ind. Eng. Chem. Res., 1993 (32):533～539
34 Baker, R. W., Simmons, V. L., Kaschemekat, J.and Wijmans, J. G., Membrane systems for VOC recovery from air streams, Filtration & Separation, 1994 (5):231～235
35 Ludgrada, B., Krzysztof, W., Marek, T., Aleksandra, J.-C., Cost analysis for the removal of volatile organic compounds from air using hybird systems: membrane separation/condensation versus membrane separation/combustion, Chem. Eng. and Proce., 1999 (38): 273～279
36 Sohn, W.-I., Ryu, D.-H., Oh, S.-J. and Koo, J.-K., A study on the development of composite membranes for the separation of organic vapors, Journal of Membrane Science, 2000(175): 163～170
37 张林、陈欢林、柴红，挥发性有机物废气膜法脱除工艺开发进展，(化工环保)，2002年待发表
38 胡宏纹主编，有机化学(第二版)，高等教育出版社，1990
39 蔡智鸣，关于十氢萘的顺反异构，大学化学，1997(2)：52～53
40 冯骏材，关于环几烷构象教学的探索，大学化学，1996(2)：23～25
41 Wang, B.G., Yamaguchi, T., Nakao, S-i., Journal of Polymer Science: Part B:Polymer Physics, 2000(38): 171～181
42 van de Witte, P., Dijkstra, P. J., van den Berg, J. W. A. and Feijen, J., Phase separation processes in polymer solutions in relation to membrane formation,Journal of Membrane Science, 1996, (1): 1～31
43 潘岚、周志军、刘茉娥，渗透汽化膜材料的选择，高分子材料科学与工程，1997(5)：138～142。