回收丁辛醇装置驰放气中丙烯和丙烷的工艺设计

本文采用压缩/冷凝/有机蒸汽膜(CCM)技术回收丁辛醇装置驰放气中的丙烯和丙烷,根据本文的工艺技术及设备选型已实际建成回收丁辛醇装置驰放气中丙烯和丙烷的装置,并已开车成功。     

有机蒸气膜分离过程

绍了有机蒸气渗透膜原理和分离过程特点,根据各生产过程工艺特点,概述了应用膜分离一压缩冷凝集成技术,分离与回收乙烯、丙烯、氯甲烷和氯乙烯等有机蒸气过程。     

膜法有机蒸汽回收技术在丙烯单体回收中的应用

阐述了膜法有机蒸汽回收的基本原理，介绍了压缩冷凝膜系统相耦合的工艺在回收尾气中丙烯单体的应用。有机蒸汽膜分离系统可以从不凝气中回收90％以上丙烯，通过比较膜系统加入后和去年同期丙烯的回收量，证明了膜系统的有效性。膜系统操作简单，占地少，没有二次污染。     

超薄聚合物表面与滴状冷凝的研究

采用等离子体聚合技术在黄铜管外表面制备了六氟丙烯、六甲基二硅氧烷的超薄聚合物薄膜,实现了水蒸气的滴状冷凝.对不同冷凝表面的传热性能进行了实验测定,并对聚合膜的表面性能进行了测试和估算.分析讨论了聚合工艺条件对滴状冷凝传热及膜与基材粘着性能的影响.     

聚丙烯厂膜回收装置的使用效果评价

聚丙烯生产过程中,闪蒸釜闪蒸出来的尾气送至气柜,经冷凝器冷凝后进入丙烯储罐,回收部分丙烯,同时排掉不凝气,但由于压缩能力和冷凝温度的制约,不凝气中仍然含有大量丙烯。通过膜回收降低单耗,增加装置收益。     

聚丙烯厂膜回收装置的使用效果评价

聚丙烯生产过程中,闪蒸釜闪蒸出来的尾气送至气柜,经冷凝器冷凝后进入丙烯储罐,回收部分丙烯,同时排掉不凝气,但由于压缩能力和冷凝温度的制约,不凝气中仍然含有大量丙烯。通过膜回收降低单耗,增加装置收益。     

具有回收丙烯氮气双功能的膜技术在聚丙烯尾气回收系统中的应用

本文对小本体聚丙烯装置原尾气回收系统存在的问题进行了分析,通过具有回收丙烯及N2双功能膜分离技术与压缩/冷凝液化回收技术的组合,回收聚丙烯装置尾气中的丙烯及N2,效果显著。     

LNG接收站蒸发气再冷凝工艺改进及性能分析

以国内某LNG接收站为例,利用HYSYS对蒸发气(Boil Off Gas,BOG)再冷凝工艺进行了模拟,在热力学分析基础提出了BOG多级压缩再冷凝工艺,并分析了性能参数对工艺能耗的影响,以此为根据提出了改进措施。经分析:多级压缩再冷凝工艺较典型的再冷凝工艺更为节能,可节约22.03%的能耗;压缩机压缩系数ri及BOG分流比xi对流程中压缩机能耗影响较大,可通过适当减小压缩系数ri与增大BOG分流比xi的方法来减少压缩机的能耗;外输LNG温度、压力对气化器、海水泵及外输泵的能耗影响较为明显,适当降低外输LNG温度与压力,能够有效改善这3个设备单元能量利用效率。     

PVC聚合尾气压缩冷凝系统工艺改进

介绍了 PVC 聚合尾气的压缩冷凝工艺流程中存在的问题并进行了分析,经过改进后的工艺采用直接加压、冷凝回收未反应的单体,通过实际运行,应用效果良好,取得了较好的经济效益和社会效益。     

液化天然气接收站蒸发气回收优化技术

以大连液化天然气(LNG)接收站为例,利用Aspen软件对LNG接收站蒸发气(BOG)处理工艺流程进行分析。提出了BOG再冷凝液化与直接压缩混合使用的运行方案,并且在再冷凝工艺流程中增加预冷装置。分析结果表明:当接收站能够稳定提供足够量LNG时,系统优先选择再冷凝工艺路线,否则自动切换至高压压缩工艺路线,并直接输送至管网。该混合使用方案能够解决因储罐及管网内BOG压力过高而放空所造成的能源浪费问题。再冷凝工艺流程中,加装预冷装置之后,压缩机较加装之前节约能耗37.4%。     

Enhanced gas separation performance of PSF membrane after modification to PSF/PDMS composite membrane in CO2/CH4 separation

Asymmetric polysulfone (PSF) membrane was developed and modified to PSF/polydimethylsiloxane (PSF/PDMS) composite membrane by dip coating technique. Effect of PDMS coating time on membrane properties was examined by scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, attenuated total reflectance‐Fourier transform infrared, and water contact angle. The increase in PDMS coating time resulted in a decrement in the thermal strength of PSF membrane. Surface contact angle values revealed that increase in PDMS coating time had increased the surface hydrophobicity in membranes. CO₂/CH₄ separation performance of membranes was evaluated, and an increase in CO₂/CH₄ ideal selectivity was observed with the increase of PDMS coating time. At feed pressure of 10 bar, the selectivity of PSF has increased up to 65% after dip coating with PDMS for 30 min. Modification of polymeric membrane into composite membrane provided a way forward towards the enhancement of gas separation performance in polymeric membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45650.     

Pervaporation separation of meOH/MTBE through CTA membrane

In the present work, the pervaporation (PV) separation of a MeOH/MTBE mixture system was studied using a CTA dense membrane. The PV performances were characterized by changing the operating conditions, such as the feed composition and permeation temperature. The results show that the CTA membrane favors MeOH permeation and exhibits specificity during the PV separation process for the MeOH/MTBE system due to the existence of the plasticization effect from the MeOH component. Furthermore, the swelling sorption measurements reaffirm that the plasticization effect has a dominant effect on the transport of the penetrants through the membrane and substantially determines the PV permeation properties. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 377–386, 1999     

聚乙烯醇/氧化石墨烯分离膜的结构与性能

成膜材料聚乙烯醇（PVA）易溶胀,稳定性差,氧化石墨烯（GO）具有很好的化学稳定性,以PVA为主要原料,GO为添加剂,聚乙二醇为造孔剂,采用共混法制备了GO含量不同的PVA/GO分离膜,并用光学接触角测量仪、超滤杯等考察了分离膜的亲水性和耐污染性;采用SEM、IR、TGA等表征了分离膜的微观形貌、热学及力学性能。结果表明：GO的加入改善了分离膜的内部孔道、亲水性、纯水通量和耐污染能力,膜的热稳定性和力学性能均得到提高,当GO含量为2%时,分离膜的综合性能达到最优。     

Phase separation in polyetherimide/solvent/nonsolvent systems and membrane formation

Phase separation phenomena of polyetherimide (PEI)/solvent/nonsolvent systems were investigated by measuring their precipitation values over the temperature range from 20 to 50°C. The solvents used are N‐methyl‐2‐pyrrolidone (NMP), dimethylacetamide (DMAC), and dimethylformamide (DMF). Nine nonsolvents were employed including water, methanol, ethanol, 1‐propanol, 2‐propanol, acetic acid, propionic acid, ethylene glycol, and diethylene glycol. Based on the measured precipitation values, critical solubility parameters for PEI were calculated, and the partial solubility boundary for PEI was obtained in a two‐dimensional solubility parameter coordinate graph. The relationship between solvent strength and membrane structure was examined using PEI hollow‐fiber membranes prepared from binary polymer solutions containing NMP, DMAC, and DMF as solvents. Water was used both as internal and external coagulants. The cross‐sectional structure and gas permeation properties of these hollow fibers were examined. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1789–1796, 1999     

富氮空气分离膜

膜法分离氮气在易燃物的贮存、装运及蔬菜、水果保鲜等方面的应用正在迅速增长。膜法适合生产95%～99%纯度范围内的氮气,优于其他传统方法。简述了膜法分离氮气的原理、膜材料及制膜工艺。     

A zeolite/polymer membrane for separation of ethanol-water azeotrope

A novel membrane effective in the separation of ethanol-water mixtures by pervaporation was made by combining zeolite NaA and poly(vinyl chloride) modified by 2-(2′-butoxyethoxy)ethyl thiolate. Under ambient conditions, a separation factor (α) of 29 and pervaporability (P) of 4 × 10^?4 g m^?1 h^?1 were obtained for the azeotropic mixture whereas, in the absence of zeolite, the respective values were 7 and 7 × 10^?5. A mechanism was proposed relating the preferential water transport at ≈? 50% zeolite content to an interfacial “phase” between the zeolite and the modified polymer.     

Ultrathin carbon molecular sieve membrane for propylene/propane separation

Ultrathin (down to 300 nm), high quality carbon molecular sieve (CMS) membranes were synthesized on mesoporous γ‐alumina support by pyrolysis of defect free polymer films. The effect of membrane thickness on the micropore structure and gas transport properties of CMS membranes was studied with the feed of He/N₂ and C₃H₆/C₃H₈ mixtures. Gas permeance increases with constant selectivity as the membrane thickness decreases to 520 nm. The 520‐nm CMS membrane exhibits C₃H₆/C₃H₈ mixture selectivity of ～31 and C₃H₆ permeance of ～1.0 × 10^?8 mol m^?2 s^?1 Pa^?1. Both C₃H₈ permeance and He/N₂ selectivity increase, but the permeance of He, N₂, and C₃H₆ and the selectivity of C₃H₆/C₃H₈ decrease with further decrease in membrane thickness from 520 to 300 nm. These results can be explained by the thickness‐dependent chain mobility of the polymer film which yields thinner final CMS membranes with reduction in pore size and possible closure of C₃H₆‐accessible micropores. © 2015 American Institute of Chemical Engineers AIChE J, 62: 491–499, 2016     

Modified polydimethylsiloxane/polystyrene blended IPN pervaporation membrane for ethanol/water separation

In this article a modified polydimethylsiloxane (PDMS) blended polystyrene (PS) interpenetrating polymer network (IPN) membranes supported by Teflon (polytetrafluoroethylene) ultrafiltration membrane were prepared for the separation of ethanol in water by pervaporation application. The relationship between the surface characteristics of the surface‐modified PDMS membranes and their permselectivity for aqueous ethanol solutions by pervaporation are discussed. The IPN supported membranes were prepared by sequential IPN technique. The IPN supported membrane were tested for the separation performance on 10 wt % ethanol in water and were characterized by evaluating their mechanical properties, swelling behavior, density, and degree of crosslinking. The results indicated that separation performance, mechanical properties, density, and the percentage of swelling of IPN membranes were influenced by degree of crosslink density. Depending on the feed temperature, the supported membranes had separation factors between 2.03 and 6.00 and permeation rates between 81.66 and 144.03 g m^?2 h^?1. For the azeotropic water–ethanol mixture (10 wt % ethanol), the supported membrane had at 30°C a separation factor of 6.00 and a permeation rate of 85 g m^?2 h^?1. Compared to the PDMS supported membranes, the PDMS/PS IPN supported blend membrane ones had a higher selectivity but a somewhat lower permeability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011