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。     

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。     

Mathematical modeling of seawater desalination by the gas hydrate method

A mathematical model of hydrate formation in the Freon R-142B-water system was developed; the problem of process optimization was solved using the throughput of the reactor with respect to gas hydrate as a criterion. The maximum throughput of the reactor, with respect to gas hydrate of 1086 kg/(m³ h), was found to be attained at a temperature of 8°C and pressure of 0.9 atm at the specified charge of 10 m³/h.     

Forecasting the economic costs of desalination technology

Government policy, in the form of grants and contracts for desalination technology, has had a major impact on steadily declining costs of desalination. The process, reverse osmosis (RO), exhibits economies of scale, which increases its feasibility as a water treatment technology for large populations. Ultrafiltration, an RO pre-treatment, also shows economies of scale. The real economic costs of desalination technology can be forecast using an ARIMA model. If these costs fall below those of conventional water treatment processes, RO and ultrafiltration become competitive with conventional water treatment technology. Our ARIMA forecasts are validated by using independent plant level cost data.     

Progress and trends in hydrate based desalination (HBD) technology: A review

The shortage of freshwater boosts the development of seawater desalination technology. As a novel method, the hydrate based desalination technology has been put forward for decades and achieved considerable development in the past years. This review focuses on the experimental progress at the aspects of the hydrate former choice, formation promotion and ion removal efficiency and conceptive innovation of hydrate separation and energy utilization. It should be noted that gaseous hydrate former with low formation pressure and insoluble liquid hydrate former are worthy for further study. Besides, the water migration caused by propane deserves to be investigated much more deeply for the potential value of wide application. Moreover, the utilization proposal of LNG cold energy brings more possibility of commercial application. In a word, the hydrate based desalination technology is hopefully an environment friendly, low-cost and widely used desalination technology in the near future.     

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.     

基于温差函数的低温多效蒸发海水淡化过程热力学分析

从分析低温多效蒸发海水淡化过程的不可逆性出发,建立了海水加热和蒸发以及冷凝器海水预热过程的火用损失关系;导出了反映低温多效蒸发过程热力学效率的不可逆温差函数,为分析、评价过程的热力学效率提供了新的工具;并在温差函数的基础上研究讨论了蒸发器总效数、冷凝器端差、首效加热蒸汽温度和相对热容率等关键因素对低温多效蒸发海水淡化过程热力学效率的影响,为过程的优化、提高过程的能量利用率指明了方向。     

Advantages of the ejectocompression process in sea water desalination

The authors introduce the various techniques developed by SIDEM for seawater desalination. Among those techniques the paper presents in detail the vapour compression process by ejectocompression.The ejectocompression process has allowed SIDEM to construct packaged type units with rising maximum capacities : 600 m³/d in 1979, 1,500 m³/d in 1980, 2,600 m³/d in 1981.The authors, as an example, give the main characteristics of 1,500 and 2,600 m³/d units and review their operating experience of this type of plants.A comparison is made with Multiflash units of same capacity namely in terms of investment costs, as well as compactness, reliability, etc.     

Kinetic investigation of CO2 and N2 clathrate hydrate formation using cyclopentane: Application in desalination

Hydrate-based desalination could be a promising technique for producing fresh water from saline water, as it is an eco-friendly process and suitable for large-scale implementation. To make the hydrate-based desalination technology easily scalable, we looked at using air (or N₂) or CO₂ as a hydrate former, along with cyclopentane (CP). Hydrate former CP helps to reduce the operating conditions, as CP forms hydrate at ambient pressure. However, hydrate formation kinetics due to water-insoluble CP is slow. In this work, the kinetics of hydrate formation in saline water were investigated and compared to identify the utility of CO₂ and N₂ as hydrate formers for desalination work. The addition of CP as a hydrate former should transform the structure of CO₂ hydrate from structure I (sI) to structure II (sII), as CP occupies the large cages (5¹²6⁴) in the gas hydrate. A set of three similar reactors were used for this study to collect data quickly. Furthermore, the triple reactor setup is a unique reactor design mounted on a shaker, and a set of SS-316 balls present inside the horizontal reactor imparts the mixing. Experiments with the CO₂-CP mixture and N₂-CP mixture have been studied in the presence or absence of 3 wt.% NaCl at 274 K and 3 MPa pressure. The gas uptake kinetics, water recovery, and separation efficiency have been investigated.     

漂白紫胶脱水除盐工艺

为减轻后续工艺的生产压力、提高生产效率,研究了在漂白紫胶水洗脱盐的同时脱水的工艺条件。为得到漂白紫胶脱水除盐工艺的优化条件,研究了不同水洗温度和水洗时间条件下漂白紫胶产品的脱水率、颜色指数和水溶物,用响应曲面法(RSM)设计试验并建立了该工艺条件的拟合方程。试验结果表明,拟合方程的拟合度较高,所建立的数学模型可以用于描述漂白紫胶的脱水除盐工艺。通过优化得到了漂白紫胶脱水除盐工艺的最优条件:温度为33℃、水洗时间为11min,可以得到脱水率为69.29%、颜色指数为1.0、水溶物为0.3969%的产品。     

Application of system analysis in two-stage reverse osmosis process design for water desalination

The application of the system analysis approach for two-stage reverse osmosis process design is illustrated in detail for the desalination of a NaCl-H₂O feed solution analogous to sea water, using Loeb-Sourirajan type porous cellulose acetate membranes.     

动力学水合物促进剂研究进展

动力学水合物促进剂是实现水合物法(NGH)储运天然气技术大规模工业化应用的关键。首先简单介绍了NGH技术与其它常规储气相比时的技术特点和优势,其次从表面活性剂类、氨基酸类、淀粉和聚合物类和纳米流体类等系统调研了动力学水合物促进剂的最新研究进展,最后分析认为氨基酸类促进剂的促进机理及纳米流体颗粒对水合物生成动力学的影响等方面应为日后该领域的研究重点。     

Floating desalination plants an engineering,operating and economic appraisal

The paper discusses the concept of floating desalination plant and compares the application of such plants with conventional land based installations.The first fully seagoing desalination vessel, named RUMAITH, is now in service with the Water and Electricity Department in Abu Dhabi. This vessel carries two 1250 m³/day MSF distillers and is complete with power generating plant and full marine and navigation facilities. The vessel design, construction and operation are described, together with the onshore facilities being installed at several coastal sites in Abu Dhabi.Floating plants can be operated as fully mobile standby and reserve capacity to reinforce land based plant. This has attractions in areas where development is rapid and other water resources are scarce. The ecnomics of floating versus land based plant are discussed for this type of application and also as an alternative to land based plant.     

Pilot and full-scale research on the vapour compression desalination process

Pilot scale tests were carried out in order to learn more about the vapour compression process at moderately high temperature (around 100°C). On the basis of the results obtained, a demonstration plant (about 240 m³/d) was built in order to test the actual validity of the process developed. Using a new type compressor the energy consumption was satisfactorily low. By the use of a vertical tube bundle with falling brine film established by screw distributors, it was also possible to obtain high overall heat transfer coefficients.     

环己酮氨肟化新工艺与HPO工艺技术及经济对比分析

Enichem公司开发的环己酮氨肟化新工艺采用双氧水和钛硅分子筛催化剂将氨氧化成羟胺,得到的环己酮肟质量好,环己酮转化率及环己酮肟选择性均达99.5％以上。新工艺与磷酸羟胺(HPO)工艺比较,具有工艺流程短,反应条件温和、能耗低、技术经济性好等优点。可变成本比HPO工艺降低460元／t,生产成本降低902元／t,投资费用为HPO工艺的18％。     

Renewable energy desalination plants for the Greek islands—technical and economic considerations

For the majority of the Greek islands, water resources are quite restricted, limiting the economic development of the local societies. To face increased potable water requirements, more than 2,500,000 m of clean water is transferred annually to these islands at a cost approaching the value of 7 /m³ On the other hand, the final cost of the locally produced water from renewable energy sources (RES) based desalination plants is expected to be quite lower than this value. The main purpose of the present study is to examine the economic viability of several representative desalination plant configurations based on the available renewable energy sources using an integrated cost-benefit analysis. In the proposed analysis all the cost parameters of the problem are taken into consideration, including the capital cost of the desalination plant, the annual maintenance and operation cost, the energy consumption cost, the local economy annual capital cost index and the corresponding inflation rate. The calculation results obtained definitely support the utilization of RES-based desalination plants as the most promising and sustainable method to satisfy the fresh, potable water demands of the small- to medium-sized Greek islands at a minimal cost, without disregarding the considerable environmental and macro-economic benefits.     

X射线衍射分析聚乙烯吡咯烷酮对水合物分解过程的影响

深水油气资源的勘探开发以及开采过程中的环保要求,使得天然气水合物动力学抑制剂使用不可避免,含动力学抑制剂的分解研究对水合物生成后的解堵具有重要的指导意义。本文在高压反应釜内采用甲烷和丙烷混合气,合成天然气水合物,并用X射线粉晶衍射仪分析了含动力学抑制剂聚乙烯吡咯烷酮的水合物分解过程。结果显示甲烷和丙烷气体会形成SⅡ型水合物,但伴随有SⅠ型甲烷水合物的生成;添加动力学抑制剂后,水合物的分解速率变慢,在-60℃,添加0.5%的聚乙烯吡咯烷酮后,分解起始的20 min内,无抑制剂体系水合物分解可达69%,而在含抑制剂体系分解约18%;SⅡ型甲烷丙烷混合气水合物分解过程中晶胞各晶面分解速率相同,没有偏好性,水合物笼作为一个整体分解,添加抑制剂不改变这种分解方式,仍以整体分解。