反渗透海水淡化系统“脱盐率与产水量下降”故障树分析

故障树分析是一种逻辑演绎的故障诊断方法,在核反应堆和航天器可靠性等领域已得到成功应用。反渗透法是目前应用最广泛的海水淡化方法。"脱盐率与产水量下降"是反渗透海水淡化系统中最为典型且损失重大的故障类型。基于对反渗透海水淡化膜组件结构和系统工作流程与机理的深入分析,给出了"脱盐率与产水量下降"的故障树;利用布尔代数求出最小割集及最小径集,完成了对故障基本事件的结构重要度分析,对故障基本事件进行了危险等级划分并提出了上述故障的处理方法。研究工作为超大规模反渗透海水淡化故障诊断专家系统中知识库的构建提供了一套科学实用的方法。     

反渗透膜的化学清洗

反渗透膜分离技术作为一门新型的高效分离、浓缩、提纯及净化技术，近30a来发展迅速，目前已广泛应用于纯水制备、海水淡化和废水处理等行业。反渗透膜是反渗透系统中的关键元件。目前国内约有几十万膜元件用户，且每年以20％～30％的速度增加。在实际应用中，膜元件都会发生不同程度的污染，导致系统进出口压差增大，产水量减少，脱盐率下降，     

海水淡化反渗透系统的系列化研究

我国反渗透海水淡化(SWRO)工程中工艺、设备等方面存在的一些问题影响了海水淡化制水成本。反渗透系统的系列化研究,不仅可以降低海水淡化成本,还可以为海水淡化技术研发和应用提供技术依据。本文详细介绍了对产水量为5~500m3.d-1的典型反渗透系统的工艺、节能技术和可靠性的研究,并形成了系列化产品的设计。通过此研究,优化了系统工艺,降低了系统能耗,为系统的安装制造提供了有力保证。     

海水淡化膜在焦化废水回用处理上的应用案例

利用海水淡化装置将焦化废水回用项目反渗透浓盐水进一步浓缩,减少浓盐水的排放,提高系统回用水收率。迁安某焦化厂在原有回用水系统中增设海水淡化装置,将反渗透浓水回收,运行结果表明:海水淡化装置应用于浓盐水的回收,装置运行稳定。装置回收率达到45%;海水淡化装置脱盐率达到99.2%,氯离子去除率达到99.3%,装置产水符合工业循环冷却水水质标准。     

某火电厂反渗透系统污染及清洗

针对某电厂反渗透系统在投运后出现的系统产水量下降、系统压差上升、系统脱盐率下降的现象,通过膜性能标准化计分析算后,认为导致反渗透膜污染的主要因素为有机物和铁污染。结合对反渗透系统膜污染物的分析,制定了清洗方案:质量分数分别为0.5%的NaOH和0.5%Na-EDTA碱洗,质量分数分别为1.5%的柠檬酸+1.5%的EDTA酸洗。化学清洗后反渗透系统产水量上升了9.2%,脱盐率上升了8.5%,反渗透进水压力降低了0.15 MPa,二段压差降低0.1 MPa。并提出了应对反渗透系统的运行管理问题的解决办法。对如何降低膜污染,延缓膜清洗周期提供参考依据。     

多介质过滤-超滤组合工艺用于SWRO预处理的中试研究

反渗透海水淡化的预处理能够有效控制膜污染,延长反渗透膜使用寿命。采用多介质过滤-超滤组合工艺对热法海水淡化浓盐水预处理进行了中试研究,组合工艺产水直接进入反渗透海水淡化除盐单元。中试结果表明,采用此组合工艺可将热法海水淡化浓盐水的浊度和SDI15值分别降至0.1 NTU和1.0以下,产水可直接安全进入后续反渗透海水淡化单元。反渗透单元脱盐率平均值为98.7%,对热法海水淡化浓盐水除盐具有较好的效果。     

反渗透海水淡化(SWRO)能量回收技术应用分析

反渗透技术已经在国内外的海水淡化工程中得到广泛应用,能量回收装置的应用使得反渗透海水淡化产水能耗大大降低,制水成本大幅下降。本文简要介绍了反渗透海水淡化能量回收技术及其经济成本分析,反渗透海水淡化能量回收装的分类,并对主流能量回收装置进行比较分析。SWRO系统中的流体能量回收利用技术有着良好的前景。     

火电厂地表水处理反渗透系统污堵分析及清洗

南方某电厂采用地表水作为反渗透进水,运行3年后出现压差升高、脱盐率和产水量降低的情况。对运行数据进行标准化处理和分析,并结合污堵物的分析结果,判断系统污染包括化学结垢、微生物、有机物和金属氧化物污堵。通过杀菌处理、碱洗和酸洗,反渗透系统压差降低、产水量增加、脱盐率恢复正常。同时,结合该电厂反渗透系统实际运行条件,提出了运行维护建议。     

反渗透系统故障分析及处理

针对启东市供电公司发电工区反渗透水处理系统脱盐率下降、压差升高、产水量下降等问题进行了现场调查研究,分析了原因,并提出了相应的处理措施,最终使问题得以解决.     

不稳定供能反渗透海水淡化中试研究

利用变频器调控水泵运行频率模拟风能供能的特性,研究了风能稳定供能、低谷波动供能、高峰供能三种工况下反渗透海水淡化系统的运行特点、运行规律。研究表明反渗透海水淡化系统在一定范围内能够适应不稳定供能,回收率在20%~35%之间变化时,产水水质稳定,平均产水脱盐率在99.4%以上。     

Myth and reality of the hybrid desalination process

The paper discusses some misconceptions that have contributed to the continued use of thermal desalination processes and promotion of the hybrid desalination process for new plants being built or considered at Middle East locations. The misconceptions are examined both on the basis of fundamental thermodynamic principles and in terms of practical engineering parameters. The analysis shows that there is no economic or performance advantage in the installation of greenfield hybrid power/thermal desalination/ seawater reverse osmosis (SWRO) plants in preference to power/SWRO plants, because the latter would produce water more cheaply under all conditions and at all fuel costs, and would provide more operational flexibility than the former. The paper identifies situations where the hybrid desalination process can be fully justified: in existing power/desalination plants, where aging boilers and multistage flash (MSF) units need to be repaired or replaced, through retrofitting and repowering. In such situations, abandonment of the MSF process would result in a reduction in the power output of the plant. The paper refers to previous work which showed that the repowering of a typical existing power/desalination station with refurbishment/replacement of the MSF units, together with the addition of SWRO units, would result in a several-fold increase in the water and power output and a dramatic improvement in the fuel efficiency, without any additions to the existing seawater intake system. The paper emphasizes the importance of test stations/demonstration plants at existing power/desalination stations in the Middle East in order to obtain data and make improvements in the technology of higher temperature SWRO, with the feed obtained from the cooling water returning from the power plant condenser and the thermal desalination plant. The paper shows that the potential benefits would easily justify the investment in research and development required to validate this concept.     

超滤膜预处理在胶州湾海水淡化的应用

采用3种中空纤维超滤组件处理胶州湾海水，从超滤膜材质、运行参数和出水水质等方面对这3种组件在海水淡化反渗透预处理中的应用进行了评价。结果表明：超滤组件运行和出水水质都很稳定，完全符合SWRO进水要求。     

Integration of seawater desalination with power generation

The economic benefits of integrating seawater desalination with power plants are discussed, starting from the first principles of thermodynamics. The concepts of the “fuel-use performance ratio” and the “power loss” method are described in the context of their usage for thermal cycle evaluation and desalination process selection, both with conventional steam cycles and with combined cycle power plants. A thermo-economic model is introduced to evaluate water and power costs and rates of return in dual-purpose power/desalination applications. The future of integrated power and desalination plants is discussed with reference to the growing role of seawater reverse osmosis (SWRO) in the desalination arena. A case study is presented to evaluate the benefits of integrating SWRO with existing power/desalination plants in the Middle East. Subject to the assumptions of the study, it is concluded that repowering and retrofitting would result in a nearly three-fold increase in the power generating capacity and an over six-fold increase in the water output, without requiring any expansion of the seawater intake system. Based on natural gas fuel, the repowered plant would also result in a 70% increase in the fuel efficiency of the station and a drastic reduction in the cost of water production. For a privatization scenario, an economic analysis is used to show that attractive rates of return would be obtained if a developer were to purchase and refurbish the existing plant, selling the products on a build own and operate (BOO) basis. In preparation for this promising application, the need for pilot plant testing at existing power/desalination stations, together with research and development work in membrane technology for high temperature operation, is emphasized.     

Pre-treatment strategies for seawater desalination by reverse osmosis system

A good quality pre-treatment process is instrumental to the successful operation of a seawater reverse osmosis (SWRO) plant. The compounds that are susceptible to foul the reverse osmosis (RO) membranes are inorganic suspended solids, sand, oil, clays, bacteria, and dissolved organic matters. In order to prevent the fouling, a pre-treatment of the raw water needs to be conducted. The pre-treatment technologies to prevent membrane fouling and to extend the lifetime of the RO membrane are commonly grouped into two categories, conventional and non-conventional. Both of these treatments are currently applied in SWRO plants in the world. The pre-treatment system applied is highly site specific and depending on the type of the feed water. This paper reviews the recent representative researches that are related to SWRO antifouling strategies and answers the most crucial questions about design and operating parameters of SWRO and its pre-treatment process. Also the economic evaluation of the SWRO system in regards to antifouling strategies' experience is discussed.     

Microbial community in seawater reverse osmosis and rapid diagnosis of membrane biofouling

Due to the acceleration of global warming and the stress that population growth has placed on the global water supply, seawater reverse osmosis (SWRO) desalination is arising as a promising technology to overcome the stress placed on current water resources. However, the biofouling of RO membranes is a common problem, as it causes flux decline, demands frequent cleanings, and consumes high energy, resulting in a shortened lifespan of the system. In an attempt to address these issues, detailed knowledge of the microbial bacteria present, which have a strong correlation between biofilm community structure and operational problems, is ultimately expected to lead to greater control of biofouling. Furthermore, a more rapid diagnosis of biofilm bacteria in SWRO processes is required for faster process feedback. In this study, previous approaches that have been proposed for understanding, diagnosing, and predicting biofouling are reviewed. Finally, the future outlook towards controlling biofouling in SWRO is discussed.     

海水反渗透淡化系统的能耗

通过对海水反渗透淡化系统（SWRO）吨水成本的分析，提出降低SWRO能耗的解决措施，采用能量透平装置（TURBO）或压力转换器（PE）回收浓水的能量传递于进水，不仅可以降低吨水电耗，也可减小一次性投资。值得关注的是，压力转换器，回收效率可达94％，在海水淡化系统中对于降低能耗有更重要的意义。     

Boron in seawater and methods for its separation — A review

The seawater reverse osmosis (SWRO) membrane desalination process is a relevant and reliable technology for desalination of seawater. However, some serious limitations had recently been discovered during field practice, among them the boron problem seems to have a critical meaning. According to the WHO regulations, the boron concentration should be reduced to less than 0.5 mg/L for drinking water. It was also reported that, this limit is rarely reached for conventional reverse osmosis desalination plants equipped with commercially available membranes. This paper reviews the extensive published literature on separation methods of boron removal from seawater.     

Cost analysis of seawater desalination with reverse osmosis in Turkey

Economically usable water resources per capita are decreasing due to excessive population increase each year in Turkey. For this reason, new water resources should be found in the near future. The potential water resources are seawater or well water both of which need removal of salinity. The most promising treatment method for salinity is reverse osmosis. While reverse osmosis becomes widespread, the cost of the process will decrease. There is no detailed information about cost of seawater desalination in Turkey. In this study, a cost analysis of seawater desalination in Turkey was performed for reverse osmosis systems. The basic parameters of cost analysis such as capacity, recovery, membrane life, energy, chemical costs and flux were evaluated based on the effects on capital, operating and total production costs.     

海水反渗透淡化技术的分析与探讨

反渗透海水淡化技术是一种高效、节能、先进的液体分离技术.论述了目前国内外海水反渗透淡化技术的应用现状,着重介绍了反渗透膜材料及特点、膜污染及清洗、典型的海水反渗透淡化流程,探讨了反渗透海水淡化技术目前存在的问题及未来发展趋势.     

反渗透膜的技术经济指标评测

反渗透膜过滤技术是一种高效、低能和易操作的液体分离技术,比传统的水处理方法效果好,可实现海水淡化、废水的循环利用及对有用物质有效回收。综述了反渗透膜技术的原理、特点及应用,重点总结了反渗透膜的技术指标,如水通量、脱盐率等,并介绍了其评测方法,同时对反渗透膜的经济指标及计算方法进行了介绍。