海上油田注水纳滤软化中试研究

针对海上油田回注驱油工艺中的海水软化问题,以胶州湾某海域海水为例,采用超滤-纳滤技术进行了中试规模的海水软化研究。考察了操作压力对两种型号（NF-A、NF-B）纳滤膜软化性能的影响,以及回收率为70%时的水质情况及其与地层水的配伍性,并对NF-A型纳滤膜进行了长期运行稳定性实验。结果表明NF-A型纳滤膜软化水能够与某海上油田地层水配伍,超滤-纳滤集成膜技术能长期、稳定地为海上油田提供软化水。     

高回收率反渗透海水淡化

传统的一级反渗透海水淡化过程中，产水回收率受渗透压的制约。在目前膜耐压性能条件下，反渗透海水淡化的回收率一般小于40％，本丈提出一种反渗透一纳滤联合脱盐的膜集成海水淡化新工艺及其过程特征方程。讨论了新工艺条件下，纳滤膜截留率r2对反渗透膜实际进水浓度c。和纳滤膜进水浓度C2p的影响，反渗透段回收率Y1。和纳滤段回收率Y2对纳滤段渗透压△π2的影响。同时比较了相同操作压力下，传统工艺与新工艺的脱盐性能，模拟计算表明，采用反渗透一纳滤联合脱盐工艺可使海水淡化总回收卒提高到60％以上。     

纳滤海水软化性能及膜污染研究

高硬度、浊度和总固溶物（TDS）含量的海水水质是制约海水淡化的瓶颈,孔径介于反渗透和超滤之间、具有荷电性质的纳滤膜在海水软化方面具有明显优势,利用小型平板膜测试设备,以人工海水为研究对象,进行了纳滤海水软化试验研究,考察了操作压力,运行时间对膜通量的影响和膜对海水中主要离子的截留效果,进而对膜污染进行了分析与探讨。     

海水/工业含盐废水纳滤除硬技术试验研究

本文利用纳滤除硬技术进行海水淡化和工业含盐废水再生利用进行研究,设计了一套卷式膜纳滤实验装置,选用陶氏纳滤膜NF90-4040和NF270-4040对模拟35‰、45‰、55‰、66‰海水进行软化,考察操作条件对纳滤膜Ca~(2+)、Mg~(2+)总硬度的脱除率的影响,并与药剂法和离子交换法除硬效果进行了比较。     

海水纳滤预处理的优化研究

纳滤已被广泛研究用于反渗透和膜蒸馏海水淡化的预处理,它能有效避免反渗透膜和膜蒸馏装置的结垢污染,但纳滤膜同样存在结垢污染问题。通过配制人工海水及人工脱硬海水等海水体系研究了硬度离子对纳滤膜无机污染的影响,并通过接触角、SEM、EDX等表征方法研究了膜面污染物的主要成分及其对膜性能的影响。结果表明,钙离子是造成纳滤膜无机污染的主要硬度离子,脱硬或脱钙处理能有效避免海水淡化过程中纳滤预处理阶段的无机结垢问题。     

膜技术在海水淡化浓盐水资源化利用中的试验研究

采用以"超滤+纳滤"(UF+NF)为主体工艺的中试装置对海淡浓盐水进行实验,探究浓盐水资源化利用的可行性。实验结果表明,超滤单元UF出水浊度0.2 NTU,SDI _(15)值0.8,满足后续有机膜单元的进水水质要求。纳滤单元选取2种不同型号纳滤膜进行实验,综合对比DK纳滤膜截留率效果较好,纳滤产水用于氯碱化盐,不仅能够节约纯水,减少原料氯化钠的消耗,同时解决了浓海水排放的问题,实现变废为宝。     

纳滤技术的应用进展及存在问题

纳滤是介于反渗透和超滤之间的一种膜分离技术,是国内外研究的热点.目前,纳滤技术在水处理领域已经得到日益广泛的应用.综述了纳滤膜在工业废水、海水淡化、饮用水、地下水和地表水处理中的应用;讨论了纳滤膜的污染问题,对两类较难处理的胶体污染和生物污染提出了相应的解决办法;最后讨论了应用NF膜的经济效益.     

纳滤海水软化性能及膜污染研究

高硬度、浊度和总固溶物(TDS)含量的海水水质是制约海水淡化的瓶颈,孔径介于反渗透和超滤之间、具有荷电性质的纳滤膜在海水软化方面具有明显优势,利用小型平板膜测试设备,以人工海水为研究对象,进行了纳滤海水软化试验研究,考察了操作压力,运行时间对膜通量的影响和膜对海水中主要离子的截留效果,进而对膜污染进行了分析与探讨.结果表明,两种荷负电纳滤膜具备良好的渗透性和分离性能.随着运行时间的延长,膜通量和离子截留率呈现一定下降趋势;结合扫描电镜和能谱的测试结果分析发现,高离子强度的海水体系中,腐植酸的优先吸附和硫酸钙晶体的形成是造成膜分离性能下降的原因,而钙与腐植酸之间的络合效应对其影响甚微.     

界面聚合聚酰胺纳滤膜渗透选择性能优化的研究进展

纳滤因其分离效率高、操作压力低、环境友好等优点,在废水处理、海水淡化和工业分离纯化等众多领域有着重要的应用。界面聚合法制备的聚酰胺（PA）纳滤膜是最为常用的纳滤膜种类之一。然而界面聚合反应速度快,如何通过调控界面聚合过程,优化纳滤膜选择分离层的结构从而提高渗透选择性,以满足不同领域对纳滤膜需求仍是亟需解决的问题。本文从影响界面聚合单体扩散因素的角度出发,综述了近年来PA纳滤膜渗透选择性能优化的研究进展,包括新型PA纳滤膜、纳米材料/PA混合基质膜及超薄PA纳滤膜3个方面,探讨了选择分离层结构调控与纳滤膜渗透选择性能优化的关系,最后指出目前界面聚合制备高渗透选择性PA纳滤膜在规模化、稳定性及可控性存在的问题,并对未来界面聚合纳滤膜在微观结构和聚合过程调控方面的研究进行了展望。     

超滤和纳滤膜分离提取纳他霉素

为提高纳他霉素(natamycin)生产提取得率,减少溶剂使用,本文采用超滤、纳滤操作对工业生产的纳他霉索发酵液进行处理。实验结果表明:操作压力、操作时间及料液流速对超滤过程有很大影响。通过超滤可将蛋白质等大分子杂质去除,然后再用纳滤膜对超滤渗透液进行浓缩纯化,对纳滤工艺的操作条件如进料压力、料液pH、浓缩倍数等进行了研究。采用超滤、纳滤技术提取纳他霉素,其收率可达62.74%。     

Complexation-Enhanced Boron Removal in a Dual-Stage Nanofiltration Seawater Desalination Process

A complexation-enhanced boron removal method in a dual-stage nanofiltration (NF) seawater desalination process was investigated. A comparative experiment of five different polyols was carried out. Sorbitol was chosen as the complexation additive because of its higher equilibrium constant. The reaction between boron and sorbitol was rapid and only slightly affected by the other ions. Due to the complexation reaction, boron rejection of dual-stage NF seawater desalination process was increased from 35% to 62% in the first stage and from 42% to 55% in the second stage. Boron concentration reached 0.1 mg/L by adjusting the complexation and pH value. Molecular structures were simulated using the molecular simulation technology. The results indicated that molecular structure and molecular size played significant roles in enhancing boron removal. Meanwhile, NaOH and sorbitol had no evident effect on the chemical structure of the membrane surface. The results indicated that complexation is an effective method to reduce boron concentration in a dual-stage NF seawater desalination process.     

Rejection of salt mixtures from high saline by nanofiltration membranes

Nanofiltration (NF) membranes have recently been employed as pretreatment unit operations in seawater desalination processes and as partial demineralization to seawater. The present paper investigates the performance of selected commercial NF membranes to reject salts of high concentrations at salinity levels representative of brackish and sea water. Two commercial nanofiltration membranes (NF90 and NF270) have been investigated in detail to study their performance in filtering aqueous solutions containing different salt mixtures in a cross-flow NF membrane process within the pressure range from 4 to 9 bar. Spiegler-Kedem model (SKM) was used to fit the experimental data of rejection with the permeate flux. The results showed that NF90 membrane was shown to have a distinct ability to reject both monovalent and divalent ions of all investigated mixtures with very reasonable values but with relatively low flux. This will make NF90 more suitable for the application in the pretreatment of desalination processes. On the other hand, NF270 can reject monovalent ions at relatively low values and divalent ions at reasonable values, but at very high permeate flux. The SKM model only fitted well the experimental data of divalent ions in salt mixture. Based on the evaluation of the overall performance of NF90 and NF270 membranes, their distinct ability to reject salts at high salinity from seawater is considered an advantage in the field of pretreatment of seawater feed to desalination units.     

海水淡化过程优化设计的研究进展

海水淡化是能源密集型工业,对淡化工艺、操作参数及设备结构等进行优化设计是降低淡化过程能耗的有效途径。本文分析了不同海水淡化方法的技术特点,详细介绍了海水淡化过程的优化设计方法及海水淡化技术集成的研究进展。     

高回收率反渗透海水淡化工艺

目前反渗透海水淡化的回收率小于40％。本文研究开发死端超滤预处理技术和反渗透一纳滤联合脱盐相结合的膜集成海水淡化新工艺,与传统工艺比较,具有装置体积小,产水回收率高等优点。文章介绍了采用新工艺的海水淡化装置样机的试制情况及现场运行结果。沿岸海水为料液,操作压力1为5．1MPa条件下,操作压力2为2.0MPa条件下,装置脱盐率99．21％,产水量3971.3L/h,产水回收率55％。海水淡化装置对海水中Ca^2 、Mg^2 、Na^ 、HCO3^-、Cl^-、SO4^2-、TDS,总碱度,总硬度的脱除率分别为99％,99．6％,99．21％,95％,99．35％,98．48％,99.21％,95％,99．42％。     

Performance of Nanofiltration Membranes in the Treatment of Synthetic and Real Seawater

Abstract

Nanofiltration membranes (NF) are being employed in pretreatment unit operations in both thermal and membrane seawater desalination processes and as partial demineralization to seawater. In order to predict NF membrane performance, a systematic study on the filtration performance of selected commercial NF membranes against seawater is presented in this paper. Two commercial nanofiltration membranes (NF90 and NF270) have been investigated in details to study their performance in filtering the salt mixture, synthetic and real seawater in a cross‐flow NF membrane process at a pressure range from 4 to 9 bars. The Spiegler‐Kedem model was used to fit the experimental data of rejection with the permeate flux in order to determine the fitting parameters of the reflection coefficient (σ) and the solute permeability (P_s). The results showed that the rejection increases with pressure for NF90 and slightly increases with pressure for NF270. Also, the NF90 membrane has shown to be able to reject both monovalent and divalent of all investigated mixtures and seawater with very reasonable values but at a relatively low flux. Moreover, it reduced the salinity of investigated seawater from 38 to 25.5 g/L using one stage of the NF membrane at 9 bars. This makes NF90 more suitable for the application in the pretreatment of desalination processes. On the other hand, NF270 can reject monovalent ions at relatively low values and divalent ions at reasonable values. It has also reduced the seawater salinity to 33.6 g/L, but at a very high permeate flux. The SKM model fitted the experimental data of divalent ions in salt mixture and seawater.     

Novel chitosan-piperazine composite nanofiltration membranes for the desalination of brackish water and seawater

A novel chitosan (CS)-piperazine (PIP) composite nanofiltration (NF) membrane with satisfied characteristics for brackish water and seawater desalination was successfully developed. PIP was mixed with CS during the interfacial polymerization (IP) process to enhance the NF membrane permeate flux. The resultant NF membranes were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscope (AFM), contact angle. Effects of CS concentration, trimesoyl chloride (TMC) concentration, reaction time and the mixing ratio of CS/PIP on NF membrane performance were investigated thoroughly. When PIP in the aqueous phase monomers reached to 25% (w/w), the PWF (60.6 L·m^?2·h^?1) was synergistically improved by nearly 2 times without a significant reduction of Na₂SO₄ rejection (89.1%). Moreover, the NF membranes possessed excellent performance for the desalination of brackish water and seawater, which showed high potential to be applied in the desalination process for water treatment.     

Utilization of solar energy for direct contact membrane distillation process: An experimental study for desalination of real seawater

Membrane distillation (MD), a non-isothermal membrane separation process, is based on the phenomenon that pure water in its vapor state can be extracted from aqueous solutions by passing vapor through a hydrophobic microporous membrane when a temperature difference is established across it. We used three commercially available hydrophobic microporous membranes (C02, C07 and C12; based on the pore size 0.2, 0.7 and 1.2 μm respectively) for desalination via direct contact MD (DCMD). The effects of operating parameters on permeation flux were studied. In addition, the desalination of seawater by solar assisted DCMD process was experimentally investigated. First, using solar power only short-term (one day), successful desalination of real seawater was achieved without temperature control under the following conditions: feed inlet temperature 65.0 °C, permeate inlet temperature 25.0 °C, and a flow rate of 2.5 L/min. The developed system also worked well in the long-term (150 days) for seawater desalination using both solar and electric power. Long-term test flux was reduced from 28.48 to only 26.50 L/m²hr, indicating system feasibility.     

阻垢剂对海水淡化膜蒸馏试验的影响

采用直接接触式膜蒸馏技术进行海水淡化试验研究。在海水温度为55℃,循环水温度为20℃的条件下,考察了不同阻垢剂用量对膜蒸馏海水淡化的影响、工艺连续运行过程中膜通量和产水电导率随时间的变化情况,确定了膜蒸馏过程稳定运行的最优浓缩倍率。结果表明,阻垢剂的加入可明显提高淡水的产水率,产水率可达到85%以上,减少了高盐度海水浓缩液的排放,膜通量稳定,产水水质好,其电导率不超过10μS/cm,膜蒸馏海水淡化具有一定的技术可行性和可操作性。     

A comprehensive review of nanofiltration membranes:Treatment, pretreatment, modelling, and atomic force microscopy

Nanofiltration membranes (NF) have applications in several areas. One of the main applications has been in watertreatment for drinking water production as well as wastewater treatment. NF can either be used to treat all kinds of water including ground, surface, and wastewater or used as a pretreatment for desalination. The introduction of NF as a pretreatment is considered a breakthrough for the desalination process. NF membranes have been shown to be able to remove turbidity, microorganisms and hardness, as well as a fraction of the dissolved salts. This results in a significantly lower operating pressure and thus provides a much more energy-efficient process. Similar to other membrane processes, a major problem in NF membrane applications is fouling. Several studies have investigated the mechanisms of fouling in NF membranes and suggested methods to minimize and control the fouling of NF membranes. For NF membrane characterizations and process prediction, modeling of NF processes and the use of atomic force microscopy (AFM) are very important. The ability to predict the performance of NF processes will lead to a lower number of experiments, saving of time and money, and help to understand the separation mechanisms during NF. A comprehensive review of NF in water treatments is presented including a review of the applications of NF in treating water as well as in the pretreatment process for desalination; the mechanism as well as minimization of NF membrane fouling problems; and theories for modelling and transport of salt, charged and noncharged organic compounds in NF membranes. The review will also address the application of AFM in studying the morphology of membrane surfaces as part of the NF membrane characterization.     

液化天然气深冷-膜蒸馏海水淡化系统集成与分析

提出了一种PRICO天然气液化-膜蒸馏（MD）海水淡化系统集成方法,利用PRICO过程压缩机出口的余热驱动MD海水淡化。采用Aspen Plus和GAMS建立了集成系统的数学模型,综合考虑系统的结构、物流物性、设备规模、操作参数等系统设计问题,分析不同设计下系统的投资、能耗、运行费用以及MD单位产水成本。模型应用于一个处理量为1 kmol/s的PRICO天然气液化系统与MD集成的案例研究。计算结果表明,单位产水成本最小时,系统产水成本为1.98 USD/m³,淡水产量为5.78 m³/h,与反渗透等海水淡化技术相比,MD在经济性方面具有较强的竞争力。