热膜耦合海水淡化系统的优化设计

采用混合节点和分配节点的概念,建立了多级闪蒸(MSF)和反渗透(RO)海水淡化集成系统的超结构模型,以年度总费用最小为目标,引入产水比的概念,并将该参数作为集成系统的一个优化变量,采用改进的遗传算法进行求解,获得了集成系统的最优结构及相应的操作条件。实例结果表明:集成海水淡化系统的淡水成本比独立运行的RO和MSF低,产水比为0.45时集成系统的费用最小,流程结构为MSF-RO。     

考虑不同水质输入的水电联产优化设计

结合已有的反渗透/多级闪蒸混产系统和发电-多级闪蒸联产系统,设计了一个新的包括热力发电系统、反渗透海水淡化系统和多级闪蒸海水淡化系统的水电联产超结构,对以不同盐度苦咸水、海水为原水的水电联产系统进行了优化设计,通过求解系统以年费用最小为目标函数的非线性数学模型,得到不同盐度下联产系统优化的生产结构. 结果表明,在低盐度(≤25000 mg/L)下采用冷凝式发电和一级反渗透产水,高盐度下采用抽汽冷凝式发电和热膜混合产水,可降低联产系统的年费用,获得较低成本的淡化水. 在本工作所定的生产规模下,优化联产方案的年费用可降低23%~36%.     

利用火电机组余热能的热膜耦合海水淡化性能分析

以沿海电厂汽轮发电机组抽汽作为热源,针对反渗透(RO)和低温多效蒸馏(LT-MED)海水淡化技术各自的特点,提出2种水电联产海水淡化方案,并进行性能分析:1种是传统的蒸汽压缩喷射器(TVC)与低温多效蒸馏系统结合的MED-TVC方案;另1种是利用电厂汽轮机抽汽余热能发电驱动反渗透膜,通过热膜耦合技术将低温多效蒸馏与反渗透海水淡化产水集成的RO-MED方案。结合某实际火电机组已经运行的海水淡化项目,建立数学模型,对2种方案的淡水产量进行了比较分析。结果表明,RO-MED方案的淡水产量约为38.26 kt/d,远大于MED-TVC方案11 kt/d的产水量。但受投资成本、运行成本、安全性等条件的制约,在实际生产中还需要依据具体情况进行选择。     

反渗透的工作性能与制水系统的经济运行

根据反渗透(RO)的生产性运行数据,探讨了RO产水电导率、脱盐率、产水量、回收率以及压降的变化规律,并就提高RO系统运行的经济性,从水量匹配、成本控制两方面,提出了一系列的对策和建议。     

船用海水淡化装置的产水水质特性及经济性分析

船用海水淡化装置是远洋船泊的必备设备之一,对产水水质特性及经济性进行研究具有重要的意义。本文设计搭建了一套板式蒸馏造水机性能测试平台,对系统产水pH和电导率随真空度变化规律以及进料水盐度和真空度对产水溶解性固体总量（TDS）的影响进行了研究,同时建立淡水成本数学模型探讨真空度和进料水流量引起的淡水产量变化对造水成本的影响,并进一步分析了油价、水价和渔船航行距离对淡水成本的敏感性问题。结果表明：真空度一定的情况下,进料水盐度升高,系统产水的TDS增大;真空度变化对系统产水pH影响不大,而对系统产水电导率、TDS和淡化水成本影响较大,且随着真空度的升高呈减小趋势。进料水流量为150L/h时,系统产水率最优造水成本最低,造水成本差价对油价的敏感性最高并且造水成本始终低于渔船运输淡水成本。     

水电联产海水淡化系统能耗指标探讨

"水电联产"模式是大型低温多效海水淡化系统的主流运行方式,可实现电能和淡水的联产联供。本文结合某电厂水电联产海水淡化工程,应用计算公式,分析了海水淡化系统的电耗、汽耗以及药耗等主要能耗指标对系统运行的影响,并对相应的指标改进方法进行探讨。     

海水淡化耦合技术的发展应用与展望

海水淡化技术主要以低温多效蒸馏(MED)、多级闪蒸(MSF)等为主的热法海水淡化技术和以反渗透(RO)、纳滤(NF)为主的膜法淡化技术两大类.根据海水淡化工程的能源条件及投资,集成多种淡化技术优势形成的耦合工艺是降低海水淡化成本、提高海水淡化效益的有效手段,这已成为大型海水淡化发展的趋势.文中主要介绍了基于MED、MSF、RO、NF等多种淡化耦合工艺在海水淡化领域中应用的研究进展,并讨论了膜-热技术组合的未来发展方向.     

钢铁工业综合废水处理回用工程实例

为提高厂区废水水资源利用率,某钢铁公司采用"格栅+高效沉淀池+V型滤池+超滤(UF)+一级反渗透(RO)+二级RO+电去离子(EDI)"工艺处理和再生回用其生产综合废水,产水有软水、除盐水和超纯水等。实际运行结果表明,该工艺设计合理,运行稳定,实现了72%～80%的高回收率废水回用;其中UF系统产水SDI_(15)2.5,一级RO、二级RO、EDI产水电导率分别为30、2.5、0.06μS/cm,特别是其产水电阻17 MΩ·cm,达到GB/T 6682-2008一级超纯水水质要求,其它各项产水指标均能够满足不同生产单元对于不同品类水质的需求,实现了厂内分区分质供水。     

煤气化氢电联产减排CO2的系统研究

征收碳税、强化石油开采以及开放二氧化碳减排贸易等措施可以促进发电行业减排CO2．但是这些措施,尤其是碳税和减排贸易,可能需要较长的时间才能在中国施行．因此,必须考虑在这段时期内如何改善减排CO2的IGCC和煤气化固体氧化物燃料电池(SOFC)混合循环的经济性,进而促进IGCC和混合循环的发展．以煤气化氢电联产系统作为尝试,设计、模拟了四种不同的联产方案,通过对各方案的投资、发电和制氢成本的分析,就氢电联产能否及如何改善经济性、如何从能量利用和成本两方面配置联产系统、以及实施碳税等措施前后如何促进发电厂减排CO2等方面进行了探讨．     

干熄焦系统热电冷联产技术的能耗分析

采用当量热力系数、发电煤耗、当量制冷火用效率的3种热经济评价模型,对干熄焦系统热电冷联产制冷与分产制冷进行了能耗分析,给出了联产系统制冷与分产制冷的节能条件,为全面研究干熄焦系统热电冷联产与分产的能耗奠定了基础。     

满足不同需求的水热电联产系统的模型和设计简

In order to improve the energy efficiency, reduce the CO2 emission and decrease the cost, a cogenera- tion system for desalination water, heat and power production was studied in this paper. The superstructure of the cogeneration system consisted of a coal-based thermal power plant （TPP）, a multi-stage flash desalination （MSF） module and reverse osmosis desalination （RO） module. For different demands of water, heat and power production, the corresponding optimal production structure was different. After reasonable simplification, the process model ot each unit was built. The economical model, including the unit investment, and operation and maintenance cost, was presented. By solving this non-linear programming （NLP） model, whose objective is to minimize the annual cost, an optimal cogeneration system can be obtained. Compared to separate production systems, the optimal system can reduce 16.1%-21.7% of the total annual cost. showing this design method was effective.     

Low temperature reject heat utilization for desalination; Economical and technical aspects

The economics of medium and large sized (1'000…10'000 m³/d) MSF/ME plants which utilize reject heat at temperatures between 50…90 °C is investigated.It is shown that for a cogeneration plant based on the Rankine cycle in combination with an evaporative desalination plant, there exists a steam condensation temperature (60…80 °C) below which the water production of the cogeneration plant is higher than the production of a power equivalent reverse osmosis plant. Power equivalent means, that the reverse osmosis plant would utilize the electricity otherwise lost when the same Rankine cycle is operated at higher condenser temperature. In spite of the higher investment costs for the evaporative plant, the specific water costs are lower than those for the power equivalent RO plant. Using a Rankine cycle for cogeneration, optimization of reject heat temperature levels is therefore crucial for obtaining economically favourable conditions.Further it is shown, that for todays and assumed future electricity rates and oil prices, the MSF/ME when powered by diesel reject heat produces cheaper water than RO or VC plants. It is necessary however, that the MSF/ME can cope with the inevitable load variations of the diesel power station. Our companys contribution in this field is briefly described.     

Integrating hybrid systems with existing thermal desalinationplants

In Gulf countries, most power plants are co-generation power desalting plants (CPDP) that generate electric energy and also produce fresh water through the desalination of seawater. This paper provides detailed technical and economical analyses to evaluate a new generation of dual purpose technology that includes the integration of reverse osmosis (RO) processes with existing thermal desalination processes and power generation (triple hybrid system) at Layyah plant, Sharjah, UAE. Hybridization of sweater reverse osmosis (SWRO) and the multi-stage flash (MSF) technology was considered to improve the performance of latter and reduce the cost of the produced water. Moreover, “idle” power in winter (seasonal surplus of unused power) was mainly utilized by RO to further reduce the cost of the hybrid system for six months of the year. Spinning reserve was also used to further reduce the cost of the proposed hybrid system. Integration ofthe three processes of MSF, MED, and RO desalination technologies could be made at different levels through which the resulting of water cost will depend on the selected configuration and the cost of materials of construction, equipment, membrane, energy, etc. Thus, the capital and annual operating costs were calculated for all potential alternatives for various plant capacities. It was found that for all plant capacities, integrated hybrid systems resulted in most cost effective solution. For example, at a capacity of 50 MIGD, the present worth of the cost was calculated to be 588.7, 443.2, and 380 million US$ for MSF, MED, and hybrid RO systems, respectively.     

Membrane processes for water supply and reuse - a question of energy consumption and cost

This paper is limited primarily to reverse osmosis which is the dominating membrane process in commercial plants. Desalination of brackish water and seawater with reverse osmosis, with special emphasis on costs and energy consumption, is the primary subject discussed in the paper. Some aspects of and development trends in industrial and domestic applications of membrane processes are also taken up, particularly with regard to by-product recovery and water reuse in connection with advanced wastewater treatment.The first RO plant to be brought into operation in Riyadh, Saudi Arabia, is located at Salbukh. The investment and total operation costs for this plant have been calculated in the paper. The water cost is at least twice as high as in a continental U.S. location. The main reason for this is the very high cost of civil and local works in Saudi Arabia. A similar calculation has been made for RO seawater desalination.Increased energy costs during the last decade have directed research and development work for all desalination methods towards reducing energy consumption. It is shown in the paper that energy recovery in connection with RO seawater desalination is particularly feasible. Different methods for energy recovery have been investigated and reported, the preferred methods depending on the size of the RO plant. A large underground RO plant for energy recovery, based on utilization of the static pressure instead of high pressure pumps, has also been studied.Another possible energy-saving, but also water quality improving method has been proposed, viz . a combined MSF-RO dual purpose plant. Excess power for reverse osmosis seems to be more and more available in Saudi Arabia due to the high power/water ratio in MSF dual purpose plants compared to the real demand for power and water.     

Optimal design of hybrid RO/MSF desalination plants Part III: Sensitivity analysis

This is the last paper in a series of three parts entitled “Optimal design of hybrid RO/MSF desalination plants”. This research is concerned with exploring the feasibility of hybridization of multi-stage flash (MSF) and reverse osmosis (RO) technologies in order to improve the performance characteristics and process economics ofthe conventional MSF process. The research project involved an optimization study where the water cost perunit product is minimized subject to a number of constraints. In the first part, the design and cost models were presented, the optimization problem formulated and solutions for a number of cases were outlined. In the second part, results were presented and discussed. In this paper we discuss the sensitivity of water cost from the alternative plant designs to variations in some cost elements and operating conditions. In general, it is concluded that, for the same desalting capacity, hybrid RO/MSF plants can produce desalted water at a lower cost than brine recycle MSF plants, while hybrid plants are characterized, by lower specific capital costs and higher water recovery fractions. Reduction in steam cost allows MSF to compete more with hybrid RO/MSF plants. This result explains the advantage of coupling MSF plants and steam power plants where the exhaust steam from the back pressure turbine represents a relatively cheaper source of heat for the MSF process. Results showed that the RO technology exceeds all other designs over the whole range of energy, chemicals and membrane costs studied here. However, water cost of the RO process was the most sensitive to variations in membrane and electricity costs compared to other hybrid configurations.     

Integration of a Gas Fired Steam Power Plant with a Total Site Utility Using a New Cogeneration Targeting Procedure

A steam power plant can work as a dual purpose plant for simultaneous production of steam and elec-trical power. In this paper we seek the optimum integration of a steam power plant as a source and a site utility sys-tem as a sink of steam and power. Estimation for the cogeneration potential prior to the design of a central utility system for site utility systems is vital to the targets for site fuel demand as well as heat and power production. In this regard, a new cogeneration targeting procedure is proposed for integration of a steam power plant and a site utility consisting of a process plant. The new methodology seeks the optimal integration based on a new cogenera-tion targeting scheme. In addition, a modified site utility grand composite curve （SUGCC） diagram is proposed and compared to the original SUGCC. A gas fired steam power plant and a process site utility is considered in a case study. The applicability of the developed procedure is tested against other design methods （STAR？ and Thermoflex software） through a case study. The proposed method gives comparable results, and the targeting method is used for optimal integration of steam levels. Identifying optimal conditions of steam levels for integration is important in the design of utility systems, as the selection of steam levels in a steam power plant and site utility for integration greatly influences the potential for cogeneration and energy recovery. The integration of steam levels of the steam power plant and the site utility system in the case study demonstrates the usefulness of the method for reducing the overall energy consumption for the site.     

多级闪蒸海水淡化与水电联产模拟与优化

海水淡化技术已成为解决淡水资源紧缺的有效途径之一.将贯通型( OTMSF)、带有盐水循环器(MMSF)和带有排热段( CMSF)的3种不同结构的多级闪蒸(Multi-stage flash,MSF)海水淡化装置分别与水电联产进行集成,并建立集成系统的数学模型,以最大经济效益为优化目标,探讨各操作参数和结构参数对集成系统性能的影响.结果表明,产水量一定时,3种集成系统的经济效益均随闪蒸级数的增大呈现出先增大后减小的变化趋势,而发电量则均出现下降的趋势.产水量Md增大时,CMSF和OTMSF系统的总经济效益均增大,且OTMSF的总经济效益高于CMSF; MMSF的经济效益明显低于前两种,其变化趋势是先升高后下降.