中空纤维膜接触器壳程添加筛网强化传质性能的研究

对中空纤维膜接触器组件壳程中添加筛网强化传质过程进行研究,考察了在不同装填分率、添加不同数目筛网情况下膜组件的流体力学性能及传质性能,并比较传质增幅与压降增幅之间关系.结果表明,添加筛网使壳程流体的非理想湍动减弱,传质性能增强,在研究范围内添加1、2及3个筛网的传质增幅分别达17.6％、33％和44％.添加1、2个筛网时传质增幅高于压降增幅,而添加3个筛网时传质增幅低于压降增幅.     

中空纤维膜接触器分离CO2/N2混合气体的研究

以氢氧化钠(NaOH)、单乙醇胺(MEA)、二乙醇胺(DEA)为吸收剂,采用疏水性聚丙烯中空纤维微孔膜接触器技术进行了从CO2/N2混合气中分离CO2的研究.从机理上简要探讨了影响CO2吸收传质的因素.结果表明3种吸收剂分离CO2的效率依次为MEA＞NaOH＞DEA,CO2的分离效率随吸收剂浓度和流速的提高而增大,随混合气流速及其中CO2浓度的增大而减小;在壳流程与腔流程的对比中腔流程对CO2的吸收效率要明显好于壳流程.     

气-液膜接触器结构优化及其传质性能研究

以海水作为吸收剂,采用模拟烟气,对气-液膜接触器进行传质性能评价试验,考察其工艺结构参数、气液介质流动速率及方式、气液压差、烟气SO2浓度等因素对传质系数、脱硫率及膜效用的影响.试验表明,在气相压力较低情况下,气液流速、气液压差对总气相传质系数影响明显,而烟气SO2浓度的影响可忽略不计.适当提高膜接触器的填充密度,增加膜吸收级数,采用错流模式的气液流动方式,均可改善烟气流场分布,增大有效传质面积,提高膜效用.与传统吸收塔相比,新型膜气体吸收装置的气液两相独立控制,可灵活应对烟气浓度变化对脱硫稳定性的影响,同时具有低气阻、耐污染、规模可线性放大等优点,工业化应用前景广阔.     

膜接触器分离混合气中二氧化碳

以N-甲基二乙醇胺（MDEA）水溶液为吸收剂,采用疏水性聚丙烯中空纤维膜组件（HFPPM）作为膜接触器,研究了膜接触器分离CO2/N2混合气传质性能,主要考察了吸收剂浓度,液速,吸收温度,原料气浓度和气速等因素对CO2吸收性能的影响,比较了同一膜组件不同流程和不同膜组件及膜形态对分离效果的影响,并对膜组件运行的稳定性进行了初步考察,实验结果表明,采用MDEA溶液和HFPPM膜接触器分离CO2/N2混合气具有较快的传质速率和较高的分离效率．     

对中空纤维膜接触器空间结构的分析与探讨

介绍了中空纤维膜接触器在气体分离、净化以及精馏结构填料替代等方面研究的最新进展,并结合笔者所进行的实验工作,从膜接触器中体系的流动方式、壳程挡板、纤维膜组器的填充密度等方面详细探讨了中空纤维膜接触器的空间结构对于过程传质和分离效果的影响.分析结果表明,在气液接触分离过程中,为有效提高膜接触分离过程的传质系数,大多数研究采用了平流中的逆流方式;壳程挡板的增设可以促进过程的分离效果,但其作用并非始终随挡板数量的增加而增强;膜组器填充密度对壳程传质的影响明显,且大多数实验结果表明,过程分离的总传质系数随填充密度的增加而减小.     

膜接触器的研究进展

膜接触器是很多具有共同特点膜过程的总称,它使用微孔中空纤维膜将两流体分隔开,膜孔为两流体提供传质的场所．与传统接触器相比有许多优点．简要阐述了膜接触器的优缺点、应用特点、相关过程和应用等,充分展示了膜接触器在化工、食品、医药等领域中的广阔应用前景．     

锅炉给水除氧方法的比较和分析

本文分析了几种常用的锅炉给水除氧技术，并指出这些方法的适用范围。在此基础上，找出它们的优缺点，提出了锅炉给水除氧方法选用的建议。     

中空纤维膜萃取的传质特性及其过程强化

膜萃取是膜过程和液液萃取过程相结合的一种新型分离技术．与通常的液液萃取过程不同，膜萃取传质中没有相的分散过程，具有其特殊的优势．文中详细介绍了中空纤维膜萃取的传质特性及其过程强化的研究进展．     

利用螺旋管技术提高中空纤维膜传质性能

在对中空纤维膜萃取以及螺旋管技术进行充分调研的基础,选择水－苯酚－30％（质量分数）TBP煤油为实验体系,传质方向为水相到有机相,在内径为1.1mm的直管中空纤维膜和螺旋状中空纤维膜中,研究了管内外流速以及螺旋特征等因素对传质系数的影响,实验结果表明,用螺旋管中空纤维膜可以有效地提高空纤维膜的传质特性,在螺旋内径为6mm,螺距为2cm的时候,总传质系数可以是相同条件下直管传质系数的1－2倍。     

真空度对膜法溶解氧解吸过程传质性能的影响

采用中空纤维膜组件对水中溶解氧脱除进行了实验研究,测定了不同操作条件下溶解氧浓度随时间的变化关系,重点考察了真空度对中空纤维膜组件传质系数的影响,并获得了传质准数关联式.研究结果表明,系统真空度对水中溶解氧的传递过程有重要影响,且真空度越高,溶解氧脱除效果越明显,传质系数越大,并进一步影响传质准数关联式.     

中空纤维支撑液膜去除水中氨氮的传质行为研究

以聚丙烯(PP)中空纤维膜为支撑体,二(2-乙基己基)磷酸(简称D2EHPA)为载体,煤油为膜溶剂,探讨D2EHPA-煤油-H2SO4中空纤维支撑液膜(SLM)体系对水中氨氮的传质行为.以去除率为指标,考察了料液初始氨氮浓度及pH值、载体浓度、反萃剂浓度对传质效果的影响;并通过对比实验分析了导致传质速率降低的主要原因.结果表明:在反萃剂H2SO4浓度为2 mol/L,料液相pH值在8～13范围内,提高料液pH值、增大膜相中载体浓度,均能提高氨氮的去除率.D2EHPA-煤油-H2SO4体系对氨氮的传质能力随氨氮浓度降低而下降.料液中氨氮浓度下降和pH值降低是导致氨氮传质速率降低的主要原因,调节料液pH值可调控和提高氨氮的去除与传质效果.     

Experimental upgrades of membrane introduction mass spectrometry for water and air analysis

Some improvements to the membrane introduction mass spectrometry (MIMS) technique, resulting in low-ppt detection limits for volatile organohalogen compounds (CX) in water (namely, chloroform, bromoform, bromodichloromethane, chlorodibromomethane, tetrachloroethylene, trichloroethylene, 1,1,1-trichloroethane, and carbon tetrachloride) and low-microgram per cubic meter detection limits for benzene, toluene, ethylbenzene, and xylenes (BTEX) in gaseous samples, are shown. A static MIMS configuration was compared to a dynamic one, the former requiring longer time to obtain the analytical response. A cryotrapping preconcentration step is introduced and linearity of response, mixture effects, and detection limits are presented. The instrumental setup consists of a hollow fiber silicone membrane, a water or air container, a cryofocusing trap based on Tenax adsorbent, a Peltier cell, and a Varian ion trap benchtop mass spectrometer is described. This instrumental setup, which we named membrane extraction trap focusing mass spectrometry, allowed the detection of CX in water at a concentration as low as 8 ppt and of benzene in air at 0.1 microg/m3. The whole assembly shows great potential for on-site routine monitoring of drinking water resources and urban and indoor air under current EU and Italian regulations.     

膜蒸馏传质强化研究

以纯水和ＮａＣｌ水溶液为实验物系,采用聚丙烯中空纤维微孔膜分别进行了渗透膜蒸馏、纯水介质膜蒸馏和盐水强化膜蒸馏实验研究,考察了盐水浓度和操作温度对膜蒸馏传质通量和热效率的影响,并对３种形式膜蒸馏的实验数据进行了对比．结果表明,盐水强化措施可以有效地提高膜蒸馏传质通量,并使过程的热效率显著提高．     

Effect of dissolved oxygen concentration on nitrate removal from groundwater using a denitrifying submerged filter

A unidirectional submerged filter system was employed to purify groundwater contaminated with nitrate by biological denitrification. The influence of the concentration of dissolved oxygen (DO) in the process was tested using ethanol, methanol and sucrose as carbon sources. Inorganic-nitrogen removal, growth of the biofilm, platable denitrifying bacteria and nitrate reducing bacteria in biofilm were studied. With regard to the type of electron donor used, the presence of oxygen decreased the removal efficiency of inorganic nitrogen and caused an increase of nitrite concentration in the treated water. These negative effects depended on utilised carbon source. Biological denitrification with alcohols such as ethanol and methanol was less affected by DO than with sucrose. The development of the biofilm was also influenced by the DO concentration as excess O₂ caused reduced biofilm growth. These biofilms developed in oxygen presence had a smaller bacterial density and a lower denitrifying bacteria versus nitrate reducing bacteria ratio, which led to an unfavorable inorganic nitrogen removal and presence of nitrite in the treated water. All these effects are more pronounced when sucrose is used as carbon source.     

聚醚砜超滤膜处理油田采出水试验研究

采用聚醚砜中空纤维超滤膜组件处理油田采出水,探讨了超滤用于油田回注水处理和采出水回用预处理效果.结果表明:聚醚砜超滤膜产水通量较高,处理水中石油类、悬浮物及其粒径中值均达到回注水的标准,浊度、TGB和IB细菌的去除率分别达100%、99%、99%.采用碱+表面活性剂复合药剂清洗可获得最佳的通量恢复.由于采出水中较高的H2S和COD含量,超滤产水的SDI15>3.0,超出后续纳滤/反渗透膜系统的进水要求.     

Boron removal by membrane contactors: the water that purifies water

The potential of membrane contactors for treating boron containing waters were investigated. In particular, experimental tests at lab scale on flat membrane modules with 40 cm² of membrane area were carried out, to identify the effect of different parameters, such as temperature, flow rate, boron concentration, etc. on the efficiency of the process. Water was chosen as the extractant in order to avoid the pollution of the feed stream and two symmetric microporous hydrophilic flat membranes with different pore size and porosity were used. From these tests, it results that the boron removal increases with the extractant temperature and with the operating flow rates. However, it is independent on the initial boron concentration in the feed water. Moreover, higher removals are obtained with the membrane with larger pore size and higher porosity. Based on the experimental results, an integrated reverse osmosis-membrane contactor system, where the membrane contactor works on the reverse osmosis permeate, was proposed and designed for a 100 m³/h fresh water production (with a boron content ≤0.4 ppm). In particular, membranes with higher porosity and lower thickness than those used in the experimental tests were considered for the calculations, in order to work at 25°C (so, there is no need of heating the extractant stream) with reasonable membrane areas. The comparison of the proposed plant to that actually used, has shown that the proposed one appears to be more effective in terms of size, energy and chemical consumption, flexibility and modularity.