造纸红液的十字流过滤速率实验研究

介绍了造纸红液及其处理现状,通过自行研制的红液陶瓷膜十字流过滤实验流程及过滤器,实验研究了十字流过滤压力、红液轴向流量等对膜渗透流过滤速率的影响。得到了膜渗透流过滤速率不与红液轴向流量成正比、仍与过滤压力成正比的实验结果,获得红液最佳膜渗透流过滤速率时的轴向流量和过滤压力的具体条件,为造纸红液的进一步过滤浓缩研究奠定了基础。     

二氧化钛动态膜在油水乳化液分离中的应用研究

以多孔管式炭膜为载体制备二氧化钛动态膜并开展动态膜分离油水乳化液的研究,考察了载体孔径对动态膜的截留率和稳定渗透通量的影响。实验结果表明,动态膜处理油水乳化液的截留率在98%以上,渗透液浓度低于8.3mg·L-1,达到国家环保排放要求;稳定渗透通量随载体孔径的增大先减小后增大。在实验基础上,提出了动态膜稳定渗透通量衰减率(FDR)的概念,并将FDR的变化趋势与动态膜类型进行关联研究。分析发现,FDR随载体孔径的增大先增大后减小,动态膜由完全堵塞过滤型过渡为中间堵塞过滤型;用中间堵塞过滤型动态膜过滤油水乳化液时,随着载体孔径的增大,渗透通量衰减变缓。     

膜孔径大小对超滤膜过滤性能影响的研究

在本研究中,将不同孔径的超滤膜用于过滤活性污泥悬浮液,以探究不同孔径膜的超滤膜过滤性能。结果表明：渗透滤液的累积体积随孔径的增大而减小。过滤初期,膜的渗透通量随着孔径的增大而增大。过滤后期,膜的渗透通量随着孔径的增大而减小。膜孔径越大,有效膜面积下降得越快,达到稳定有效膜面积的时间越短。同时,通过计算孔堵塞阻力和膜的有效膜面积可以很好地评估超滤膜过滤性能,孔径小的膜孔内阻力占比小、受污染程度低和抗污性能好。     

无机膜错流微滤技术在菠萝汁澄清中的实验研究

无机膜具有耐高温、耐腐蚀、机械强度大、耐微生物侵蚀等特性,广泛应用在液体分离领域。将膜技术和错流过滤技术相结合是目前膜分离领域的热点。本文以平均孔径为0.22滋m的平板无机Ni膜为过滤介质,对菠萝汁在错流过滤状态下进行了澄清实验,通过考察膜的渗透通量以及菠萝汁过滤前后的粒度分布情况,初步研究了无机Ni膜在错流过滤状态下的过滤性能。     

反渗透、超滤等技术交流会

1987年“全国反渗透、超过滤、微孔过滤和渗透蒸发技术交流会”于1987年11月3日至6日在浙江省湖州市召开。参加会议的有我国从事反渗透、超过滤、微孔过滤、渗透蒸发和膜蒸馏的高等院校、科研单位、膜设备制造厂以及使用膜设备的56个单位的113名代表。会议由     

膜振动过滤通量的实验研究

针对膜过滤过程中,因污染造成膜渗透通量下降等问题,提出了全新的将膜过滤与机械振动结合的膜振动过滤方式;用粘土悬浮液做正交实验,对比了在相同操作条件下,膜振动过滤及无振动膜过滤的膜过滤通量随时间的变化情况,表明膜振动过滤通量比无振动膜过滤通量大,并验证膜振动过滤方式的可行性;通过对影响因素的分析明确了振动频率适中、振动振幅较大时,膜过滤通量越大的原因。     

TiAl金属间化合物分离膜在TiCl_4工业分离中的应用

TiAl金属间化合物分离膜具有高过滤精度和长期稳定的过滤通量。使用TiAl金属间化合物分离膜的固液分离可以大大提高TiCl_4生产工业中的生产效率。反吹和反冲洗技术相结合,确保了长期密封和过滤过程,大大降低了劳动强度,避免了污染。本文对滤饼层中固体颗粒的清洗和再生进行了研究,结果表明,反向过滤可以显着提高TiAl膜的渗透通量,并且采用化学清洗效果最好。     

颗粒体系错流过滤过程的数学模拟

以流体力学理论为基础,通过颗粒在水溶液中的受力分析,结合早期的阻塞过滤模型和近期的滤层过滤模型,建立了一种新的颗粒体系错流过滤过程的数学模拟方法,在该模拟过程中同时考虑了膜孔径和颗粒大小两种分布,并对具有相同平均孔径而孔分布不同的情形对膜渗透通量的影响进行了模似,经实验验证,模拟结果与实验值能够较好地吻合。     

动态膜的形成机理及其水处理性能研究

以陶瓷管为载体,对高岭土动态膜的形成及其污水处理性能进行了详细的研究.实验中采用错流过滤方式涂膜,考查了跨膜压差、涂膜液浓度、错流速度及涂制时间等对动态膜形成的影响.通过对实验数据分析可知,动态膜形成初期10～13 min,膜的形成过程可用标准过滤模型描述,在此期间颗粒堵塞载体膜管孔道,致使渗透液通量急剧减小;之后,膜的形成过程符合滤饼过滤模型,这一阶段颗粒主要在载体膜管内壁面沉积,渗透液通量缓慢下降直至基本稳定.制备的动态膜可用于处理城市污水厂二级出水,动态膜对浊度去除率基本上为100%,对COD也有一定的去除作用.     

膜材料的开发

自从五十年代后期,膜就开始用来净化水。用来处理水的膜分离技术有反渗透、超滤和微孔过滤。在反渗透工艺中,溶液在一定的压力下(通常225磅/英寸~2左右)通过一个半渗透膜。     

Application of water vapor and hydrogen-permselective membranes in an industrial fixed-bed reactor for large scale methanol production

Coupling reaction and separation in a membrane reactor improves the reactor efficiency and reduces purification cost in the next stages. In this work a novel reactor consisting two membrane layers has been proposed for simultaneous hydrogen permeation to reaction zone and water vapor removal from reaction zone in the methanol synthesis reactor. In this configuration conventional methanol reactor is supported by a Pd/Ag membrane layer for hydrogen permeation and alumina-silica composite membrane layer for water vapor removal from reaction zone. In this reactor syngas is fed to the reaction zone that is surrounded with hydrogen-permselective membrane tube. The water vapor-permselective membrane tube is placed in the reaction zone. A steady state heterogeneous one-dimensional mathematical model is developed for simulation of the proposed reactor. To verify the accuracy of the model, simulation results of the conventional reactor is compared with the available plant data. The membrane fixed bed reactor benefits are higher methanol production rate, higher quality of outlet product and consequently lower cost in product purification stage. This configuration has enhanced the methanol yield by 10.02% compared with industrial reactor. Experimental proof-of-concept is needed to establish the safe operation of the proposed configuration.     

Systems analysis of a multi-stage tubular module reverse osmosis plant for sea water desalination

A tubular reverse osmosis system for sea water has been analyzed based on current cellulose acetate membrane technology. The possibility of staging product water in two and three stages has been studied. A dynamic programming model is developed and solved to arrive at optimum operating parameters for the two-stage and three-stage designs.A variable membrane permeability model is used to simulate operating conditions along the tube length within a stage, to arrive at optimum membrane curing temperatures. Actual performance data from UCLA's experimental plant at La Jolla, California was used. Cost analysis and equations are derived from actual costs incurred at La Jolla.     

非对称陶瓷膜管渗透性能的CFD模拟研究

陶瓷膜因其化学稳定性好、机械强度大等优点得到广泛应用。计算流体力学(CFD)的快速发展使得计算模拟成为研究和优化陶瓷膜管结构性能的有效手段。为了优化非对称结构陶瓷膜管的结构和操作参数,对其渗透性能进行了CFD计算模拟。针对非对称结构陶瓷膜管的膜层和过渡层的厚度在10 μm级的特点,采用Navier-Stokes方程和Darcy定律来分别描述膜管内和膜多孔介质内的纯水流动,利用多孔介质模型描述膜管的主体支撑层,用多孔跳跃边界简化膜管的膜层和过渡层,利用Konzey-Carmen方程对膜元件各层的渗透率进行估算。计算结果与实验值吻合较好,为优化陶瓷膜管的通道结构提供了便捷的工具。     

Permeate-Flux Declination for Ultrafiltration along Membrane Tubes

The correlation equations for predicting local permeate fluxes in tubular-membrane ultrafilters were derived from mass and momentum balances by the modified resistance-in-series model with the considerations of the increment of concentration polarization and the declines of transmembrane pressure and flow rate, along the membrane tube. Ultrafiltration of dextran T500 aqueous solution in a tubular microporous ceramic module has been carried out under various feed concentrations, transmembrane pressures, and feed flow rates, and many experimental data of ten-point local permeate fluxes along the tube were obtained to confirm the correlation predictions. The increment of concentration polarization, as well as the decline of permeate flux, along the tube was also discussed.     

Dynamic modeling and operability analysis of a dual-membrane fixed bed reactor to produce methanol considering catalyst deactivation

The goal of this research is dynamic operability analysis of dual-membrane reactor considering catalyst deactivation to produce methanol. A dynamic heterogeneous one-dimensional model is developed to predict the performance of this configuration. In this configuration, a conventional reactor has been supported by a Pd/Ag membrane tube for hydrogen permeation and alumina–silica composite membrane tube to remove water vapor from the reaction zone. To verify the accuracy of the considered model, the results of conventional reactor are compared with the plant data. The main advantages of the dual-membrane reactor are: higher catalyst activity and lifetime, higher CO₂ conversion and methanol production.     

LTA zeolite composite membrane preparation,characterization and application in a zeolitic membrane reactor

An LTA membrane has been crystallized inside a porous ceramic tube and applied to synthesis of methanol from carbon dioxide and hydrogen in a zeolite membrane reactor (ZMR). The results obtained with the ZMR were compared with those gained from one traditional reactor (TR) used under the same operating conditions. CO₂ conversion obtained with the ZMR at 210 °C reached 17% under conditions where the equilibrium value without zeolite membrane (TR) is equal to about 6%.     

Theoretical Investigation of a Pd‐membrane Reactor for Methanol Synthesis

A numerical study is performed in order to evaluate the performance and optimal operating conditions of a palladium membrane reactor for methanol synthesis. A novel reactor configuration with a Pd wall, which is perm‐selective to hydrogen, has been proposed. In this configuration the reactants are added to the tube side while pure hydrogen is added to the shell side, as a result, the hydrogen diffuses across the membrane from the shell side to the tube side. In this membrane reactor, hydrogen penetrates to the reaction side in order to maintain a suitable hydrogen level in the whole length of the reactor and shift the equilibrium reaction. The effects of different parameters on the methanol output mole fraction were investigated in the co‐current mode. These parameters were membrane thickness, reaction side flow rate, reaction side pressure, shell side pressure and H₂/CO₂ ratio in the feed.     

以TPABr为模板剂的ZSM-5分子筛膜的合成与表征

以四丙基溴化铵(TPABr)为模板剂,直接在多孔的α-A1_2O_3陶瓷管外表面,经过重复合成制得了渗透通量较大的ZSM-5沸石分子筛膜。以合成ZSM-5沸石的DTA/TGA分析结果为依据,确定了去除ZSM-5沸石膜中模板剂的热处理制度。用X R D和S E M对Z S M-5沸石分子筛膜进行了表征,膜的分离因子用单一的氢气和氮气的渗透通量的比值表示。X RD分析表明陶瓷基质表面的膜层是ZSM-5沸石晶相,S E M结果显示合成的沸石膜层晶体相互交连,形成一种连续的多晶层,厚度约10μm。H_2、N_2对分子筛膜的气体渗透表明,合成的ZSM-5沸石膜的H_2/N_2理想分离因子为2.87。     

Optimal conditions of isobutane dehydrogenation in radial flow moving bed hydrogen-permselective membrane reactors to enhance isobutene and hydrogen production

In the isobutane dehydrogenation process, coupling reaction and separation and optimization of the intensified process can improve the isobutane conversion and selectivity, reduce operational costs and lets to produce pure hydrogen. In this research, the radial flow moving bed reactors in the Olefex technology have been supported by Pd–Ag membrane plate to remove hydrogen from the reaction zone. The reactions occur in the tube side and the hydrogen is permeated from the reaction zone to the sweep gas stream. The proposed configuration has been modeled heterogeneously based on the mass and energy conservation laws considering reaction networks. To prove the accuracy of the considered model, the simulation results of the conventional process have been compared against available plant data. The Genetic algorithm as an effective method in the global optimization has been considered to optimize the operating condition of membrane reactors to enhance isobutene productivity. In this optimal configuration, the isobutene production has been enhanced about 3.7%.     

Methane steam reforming in a Pd-Ru membrane reactor

Methane steam reforming has been carried out in a Pd-Ru membrane reactor at 500–600 ‡C. The membrane reactor consisted of a Pd-6%Ru tube of 100 mm wall thickness and commercial catalysts packed outside of the membrane. The methane conversion was significantly enhanced in the membrane reactor in which reaction equilibrium was shifted by selective permeation of hydrogen through the membrane. The methane conversion at 500 ‡C was improved as high as 80% in the membrane reactor, while equilibrium conversion in a fixed-bed reactor was 57%. The effect of gas flow rate and temperature on the performance of the membrane reactor was investigated and the results were compared with the simulated result from the model. The model prediction is in good agreement with the experimental result. In order to apply the membrane in practice, however, the thickness of the membrane has to be reduced. Therefore, the effect of membrane thickness on performance of the membrane reactor was estimated using the model.