Experimental studies on dynamic process of energy recovery device for RO desalination plants

A two-chamber hydraulic energy recovery unit with a programmable controller and a data acquisition system was set up. Tap water was used as the working fluid instead of the actual seawater and concentrate in SWRO desalination plants. Experimental results were obtained on the fluctuations of the pressure and flow rate to and from the energy recovery unit. Characteristics of the pressure at the chamber ends were discussed at the conditions of the chambers set horizontally or vertically, with and without pistons.     

基于层次分析法的重大危险源模糊综合评价

介绍我国目前采用的几种重大危险源评价方法。利用层次分析法的原理,针对重大危险源评价因子建立层次结构模型,构建比较矩阵;将成对比较矩阵的特征向量作为重大危险源评价的权重,确定了评价因子的影响力排序;建立了重大危险源危险度评价指标体系,提出了一种新的重大危险源危险度评价方法,为重大危险源分级和监控管理提供了依据;并通过实例进行了基于层次分析法的重大危险源评价方法的实际运用。     

Application of alternative energy integration technology in seawater desalination

Technologies that are used mainly in the seawater desalination industry are reviewed and evaluated in this paper. The utilization principles, applications and problems of solar and nuclear energy in desalination are respectively summarized and discussed with emphasis. Other alternative energies such as wind, hydro-energy and ocean energy are also presented. Applying alternative energy integration technologies in seawater desalination as a key proponent to meet the future challenges of sustainable development and/or energy issue was also discussed.     

Potential of heat pipe technology in nuclear seawater desalination

Heat pipe technology may play a decisive role in improving the overall economics, and public perception on nuclear desalination, specifically on seawater desalination. When coupled to the Low-Temperature Multi-Effect Distillation process, heat pipes could effectively harness most of the waste heat generated in various types of nuclear power reactors. Indeed, the potential application of heat pipes could be seen as a viable option to nuclear seawater desalination where the efficiency to harness waste heat might not only be enhanced to produce larger quantities of potable water, but also to reduce the environmental impact of nuclear desalination process. Furthermore, the use of heat pipe-based heat recovery systems in desalination plant may improve the overall thermodynamics of the desalination process, as well as help to ensure that the product water is free from any contamination which occur under normal process, thus preventing operational failure occurrences as this would add an extra loop preventing direct contact between radiation and the produced water. In this paper, a new concept for nuclear desalination system based on heat pipe technology is introduced and the anticipated reduction in the tritium level resulting from the use of heat pipe systems is discussed.     

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.     

Coupling of nuclear heating reactor with desalination process

A seawater desalination plant using a nuclear heating reactor (NHR) coupled with the multi-effect distillation (MED) process was developed by the Institute of Nuclear Energy Technology, Tsinghua University, China. The seawater desalination plant was designed to supply potable water demand to some coastal location or island where both fresh water and energy sources are severely lacking. The NHR design possesses intrinsic and passive safety features, which was demonstrated by the NHR-5 experiences. The intermediate circuit and steam circuit were designed as the safety barriers between the NHR and MED desalination systems. With the power range of the heating reactor within 10 to 200 MWt, the desalination plant could provide 8,000 to 160,000 m³/d of potable water of appropriate quality. The design concept and parameters, safety features, and comparative investigation of coupling schemes are presented in the paper.     

层次分析法在淮河干流水量分配中的应用

为了解决淮河流域水资源短缺、时空分布不均等水资源问题,结合淮河干流实际情况,运用层次分析法建立水量分配模型,并运用于淮河干流水量分配,体现了注重公平且适度兼顾效率的水量分配原则,分水结果与现状分水较吻合,满足用水区域的用水要求。     

Binary metal oxides incorporated polyethersulfone ultrafiltration mixed matrix membranes for the pretreatment of seawater desalination

In this study, an attempt was made to pretreat seawater using polyethersulfone (PES) mixed matrix membranes (MMMs) incorporated with titania-based binary metal oxides. Two different titania-based binary metal oxides were prepared, namely titania-zirconia (TiZr) and titania-zinc oxide (TiZn). The influence of hydrophilic and negatively charged sulfonated poly(ether ether ketone) (SPEEK) polymer as additive of PES MMMs was also studied. Morphological and elemental analysis revealed that both ZrO₂ and ZnO were well dispersed in the as-prepared binary metal oxide TiZr and TiZn, respectively._. Thermogravimetry analysis indicated the good compatibility of TiZr and TiZn with the SPEEK/PES polymer. The binary metal oxide incorporated SPEEK/PES MMMs exhibited improved hydrophilic properties with a low water contact angle of 57° ± (0.6). SPEEK/PES MMMs incorporated with 0.5 wt% TiZr exhibited the highest permeability of 3.11 × 10⁻⁷ ± (0.2) m/s·kPa. Seawater pretreatment performance of membranes evaluated using natural organic matters containing high salinity feed water. TiZr and TiZn incorporated SPEEK/PES MMMs exhibited 95% rejection for humic acid. SPEEK/PES MMMs loaded with 0.5 wt% TiZr also showed the highest water flux and 87% water recovery within 90 min of seawater filtration. Both PES/SPEEK/TiZr and PES/SPEEK/TiZn MMMs exhibited superior antibacterial activity.     

A hybrid expert-procedural system for the design of reverse-osmosis desalination plants

The problem of computer-aided design and synthesis of a reverse-osmosis desalination plant is presented. A hybrid expert-procedural system has been developed that deal with the synthesis problem at two levels of abstraction. The expert part of the system uses qualitative data, and through heuristics, makes decisions about the structure of the plant. The procedural part of the system uses the decisions of the expert part as a basis for detailed design and optimisation. The heuristics used in the expert part come from experienced designers and from proposals of membrane manufacturers. The detailed calculations are based on mass balance equations and correlations for the permeators. The system developed can be used to propose a reverse-osmosis plant structure and to perform detailed calculations for possible design scenarios envisaged by the user. A case study on such a plant is also given and shows how the expert system handles the design problem of a reverse osmosis desalination plant.     

Effect of different operation pressures for various membranes on the performance of RO plants

The aim was to study the effect of different operation pressures on the performance of reverse osmosis (RO) plants for various types of membranes. The study was conducted in a pilot plant at the University of Basrah, College of Engineering, which has a capacity of 9 m³/h. The plant is comprised of two parallel vessels containing five elements for each vessel, 8″ in diameter and 40″ in length. The first vessel has Saehane membranes, type RE8040BE-400 ft² manufactured in South Korea. Koch membranes, type 8822-XR-365 ft² made in the US, were used in the second vessel. The pilot plant uses brackish water from the Tigris River with TDS <600 ppm. The new type of RO membranes (Saehane) were used for the first trial for production of desalted water from brackish water less than 600 ppm and the results were compared with performance of the Koch membranes. It was found that over 180 days of continuous operation, the amount of permeate for Saehane membranes is larger than Koch membranes by about 26%. It was also observed that the quality of permeate water stream for Koch membranes is less than for the Saehane membranes by about 11%.     

小直径钻头层次优选AHP模型的确立及应用

钻井中,钻头费用在1口井的总投资里所占的比例一般不大,但钻头的使用效果会直接影响整个钻井。由于小直径钻头的特殊性,轴强度低,落井后不易打捞,以及转速、钻压、井下工具等因素的限制,小直径钻头的优选较常规尺寸更重要,在进行小直径钻头评价和优选时,每种类型的小直径钻头都包含有各类技术经济指标,很多指标既相互依赖,又相互矛盾,因而给决策、评价带来很大困难。另外,决策人员有时很容易受某一具体指标的影响,常常会单凭一项经济或技术指标而肯定或否定某一类型的钻头。为此,本文对中原油田小井眼(458″)钻头尝试运用综合评价法中的层次分析(AHP,A nalyticH ierarchy Process)理论进行评价与优选。     

用层次分析法确定采矿方法数值决策的权系数

通过实例论述了在采矿方法模糊决策中用层次分析法确定权系数的原理和方法。     

层次分析法在氟塑料软管组件研制方案中的应用

应用层次分析法(AHP法)建立风险评价结构模型,把大型客机重型高压(SAE AS604标准)氟塑料软管研制方案中不能量化的技术、质量、进度等风险因素划分成相互联系的有序层次,通过结构性方法减少主观因素的影响,从而选出风险相对较小的研发方案供决策人员参考。     

A hybrid solar desalination process of the multi-effect humidification dehumidification and basin-type unit

This paper presents a hybrid solar desalination process of the multi-effect humidification dehumidification and the basin-type unit. The sketch of the hybrid solar desalination process is given. The solar vacuated tube collector is employed in the desalination system, multi-effect humidification dehumidification desalination (HDD) process is plotted according to pinch technology, and then the water rejected from multi-effect HDD process is reused to desalinate in a basin-type unit further. The gain output ratio (GOR) of this system will rise by 2–3 at least through reusing the rejected water. The research proves that the multi-effect HDD has much room to be improved. A hybrid solar desalination process of the multi-effect humidification dehumidification and the basin-type unit should be noticed.     

大型低温多效蒸发海水淡化装置传热过程热力损失分析

基于低温多效蒸发海水淡化装置的各种阻力和海水沸点升高（BPE） 关联式,计算了海水淡化装置中流动阻力、海水沸点升高等造成的传热过程热力损失,分析了各项热力损失在各效蒸发/冷凝器中的分布、随蒸发/冷凝器数量的变化规律等。结果表明：产水量、浓缩比和加热蒸汽温度等参数均保持不变的前提下,总的热力损失随着装置的蒸发/冷凝器数量而增加;BPE引起的热力损失占最大比例,但流动阻力引起的热力损失不可忽略。通过对海水淡化装置热力损失的分析,提出了低温多效蒸发海水淡化装置“小温差、低流阻、饱和态、高敏感”的工作特征理论。     

层次分析法评价电石渣资源化利用途径的研究

依据层次分析法原理,从经济、环境和资源化3个影响因素建立电石渣资源化途径优选的递阶层次结构模型.以山东某化工厂生产废物电石渣为研究案例,从电石渣组成成分与含量分析的角度出发,结合电石渣各资源化途径独特要求,探讨电石渣资源化特性与资源化途径的密切关系,拟合出电石渣的各种资源化特性,作为结构模型中的资源化因子.然后分别对模型中的3个影响因素进行定性和半定量化处理,最终实现电石渣资源化途径优选的决策评价.     

Thermoeconomic design of a multi-effect evaporation mechanical vapor compression (MEE–MVC) desalination process

Desalination of seawater accounts for a worldwide water production of 24.5 million m³/day. A “hot spot” of intense desalination activity has always been the Arabian Gulf, but other regional centers of activity emerge and become more prominent, such as the Mediterranean Sea and the Red Sea, or the coastal waters of California, China and Australia. Despite the many benefits the technology has to offer, concerns rise over potential negative impacts on the environment. Key issues are the concentrate and chemical discharges to the marine environment, the emissions of air pollutants and the energy demand of the processes. To safeguard a sustainable use of desalination technology, the impacts of each major desalination project should be investigated and mitigated by means of a project- and location-specific environmental impact assessment (EIA) study, while the benefits and impacts of different water supply options should be balanced on the scale of regional management plans. In this context, our paper intends to present an overview on present seawater desalination capacities by region, a synopsis of the key environmental concerns of desalination, including ways of mitigating the impacts of desalination on the environment, and of avoiding some of the dangers of the environment to desalination.     

Application of the multi-effect process at high temperature for large seawater desalination plants

A large sea water desalination plant, using the multi-effect process at high temperature has been described and a comparison is given with the other distillation processes.The multi-effect plant is easily adaptable in a wide range of operating conditions. It has a low total energy consumption (8.75 KWh per m3 produced (expressed as electrical energy). A high GOR is obtained (12.4). Compared with a MSF of the same production capacity, the investment costs are smaller. This leads to a substantial decrease in cost of the produced water. The technology of horizontal sprayed tubes is a proven one and has been executed more than a hundred times on small and medium units.     

Concentrating solar power for seawater desalination in the Middle East and North Africa

The paper presents a long-term scenario for the demand of freshwater in the Middle East and North Africa (MENA) and shows how it may be covered by a better use of the existing renewable water sources and by sea water desalination powered with solar energy. Growth of population and economy, increasing urbanization and industrialization, and the rather limited natural resources of potable water in MENA are leading to serious deficits of freshwater in many parts of MENA. Modern infrastructure for water distribution, enhanced efficiency of use and better water management are to be established as soon as possible. However, even the change to best practice would leave considerable deficits, which are poorly covered by over-exploiting groundwater resources. Increased use of desalted seawater is therefore unavoidable in order to maintain a reasonable level of water supply. The desalination of seawater based on fossil fuels is neither sustainable nor economically feasible in a long-term perspective, as fuels are increasingly becoming expensive and scarce. Concentrating solar power (CSP) offers a sustainable alternative to fossil fuels for large scale seawater desalination. CSP can help to solve the problem, but market introduction must start immediately in order to achieve the necessary freshwater production rates in time.     

Fire hazard evaluation of thermoplastics based on analytic hierarchy process (AHP) method

Combustibility performance of 14 compositions including five main thermoplastics (polycarbonate (PC), polypropylene (PP), high impact polystyrene (HIPS), acrylonitrile butadiene styrene (ABS) and poly (vinyl chloride) (PVC)) was tested by cone calorimeter. The fire growth index, total heat release amount index, total smoke release amount index and toxicity product index were calculated, based on which an index system for evaluating fire hazard was set up. All factors in this index system had been analyzed by the analytic hierarchy process, and the specific weight for each factor had been determined. Then fire hazard of thermoplastics was evaluated considering integrated fire hazard index. The results show that fire hazards of HIPS‐phosphate fire retardant (PFR), PVC‐non‐flame retardant, ABS‐brominated flame retardant (BFR) and PC/ABS‐PFR are higher than PC‐BFR and PP‐non‐halogenated flame retardant. Copyright © 2009 John Wiley & Sons, Ltd.