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.     

Systems analysis of dual-purpose nuclear power and desalting plants Part I. Optimization

The optimal process design of a dual purpose plant for producing power and water is investigated. A nuclear reactor and steam turbine power generator for steam and power production is coupled with two water plants, a multi-stage flash plant and a reverse osmosis plant. The total system cost for producing given levels of power and water is minimized. Optimal designs are presented for several combinations of water and external power demands ranging from 25 mgd to 150 mgd and from 50 MWe to 200 MWe.     

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.     

Conceptual design of ammonia‐based energy storage system: System design and time‐invariant performance

Chemicals‐based energy storage is promising for integrating intermittent renewables on the utility scale. High round‐trip efficiency, low cost, and considerable flexibility are desirable. To this end, an ammonia‐based energy storage system is proposed. It utilizes a pressurized reversible solid‐oxide fuel cell for power conversion, coupled with external ammonia synthesis and decomposition processes and a steam power cycle. A coupled refrigeration cycle is utilized to recycle nitrogen completely. Pure oxygen, produced as a side‐product in electrochemical water splitting, is used to drive the fuel cell. A first‐principle process model extended by detailed cost calculation is used for process optimization. In this work, the performance of a 100 MW system under time‐invariant operation is studied. The system can achieve a round‐trip efficiency as high as 72%. The lowest levelized cost of delivered energy is obtained at 0.24 $/kWh, which is comparable to that of pumped hydro and compressed air energy storage systems. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1620–1637, 2017     

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.     

Conceptual design of a novel hybrid fuel cell/desalination system

A novel concept for integrating fuel cells with desalination systems is proposed and investigated in this work. Two unique case studies are discussed — the first involving a hybrid system with a reverse osmosis (RO) unit and the second — integrating with a thermal desalination process such as multi-stage flash (MSF). The underlying motivation for this system integration is that the exhaust gas from a hybrid power plant (fuel cell/turbine system) contains considerable amount of thermal energy, which may be utilized for desalination units. This exhaust heat can be suitably used for preheating the feed in desalination processes such as reverse osmosis which not only increases the potable water production, but also decreases the relative energy consumption by approximately 8% when there is an increase of just 8°C rise in temperature. Additionally, an attractive hybrid system application which combines power generation at 70%+ system efficiency with efficient waste heat utilization is thermal desalination. In this work, it is shown that the system efficiency can be raised appreciably when a high-temperature fuel cell co-generates DC power in-situ with waste heat suitable for MSF. Results indicate that such hybrid system could show a 5.6% increase in global efficiency. Such combined hybrid systems have overall system efficiencies (second-law base) exceeding those of either fuel-cell power plants or traditional desalination plants.     

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.     

Analysis of water production costs of a nuclear desalination plant with a nuclear heating reactor coupled with MED processes

A nuclear heating reactor (NHR) was designed with the required inherent safety and simplified design features. Power capacity of the NHR-200 (200 MW(th), with steam production of 380 t/h) is compatible with reasonably sized desalination plants. Thermal-hydraulic parameters of the produced steam (2.4 bar and 124°C) are suitable for coupling with distillation processes. Economic competitiveness of the NHR desalination plant is the key point to which the public and decision-makers are paying good deal of attention. Coupling of the NHR with selected MED processes and design parameters of an integrated desalination plant are described. Results of analyses of water production costs are presented as well. Based on the economic evaluation, the average energy cost of the nuclear plant may reach 5.44 $/t of steam, and the provided water production cost may reach 0.72 $/m³ and 0.76 $/m³ for coupling with HT–VTE–MED and LT–HTE–MED processes, respectively.     

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.     

Basic considerations influencing the choice of materials for thermal seawater desalination plants

Model calculations were used to ascertain in what circumstances extra investment in better materials pays off for thermal seawater desalination plants. The most important result obtained is that such expenditure is definitely worthwhile in all cases in which it allows plant lifetime to be prolonged by several years.The study reveals that in such cases even substantially increased investment cost can lead to a marked reduction in production cost and for this result to be achieved it is sufficient for plant lifetime to be extended by only a few years. A plant with an investment cost nearly 50% higher produces water at lower cost than the cheaper plant if plant lifetime is increased by as little as two years; availability is improved by 14%, and annual maintenance cost is halved, the decisive factor, however, is the increased lifetime.     

Simulation and optimization of multi effect desalination coupled to a gas turbine plant with HRSG consideration

There are a large number of gas turbine power plants in the south of Iran that could be exploited to produce fresh water and overcome water shortage. In order to combine gas turbine power plant and thermal desalination, heat recovery steam generator (HRSG) is required for producing steam. Few papers in literature have investigated this combination and none of them has considered HRSG in their studies. Thus, in this paper, multi-effect evaporation thermal vapor compression desalination (ME-TVC) is coupled to gas turbine plant through HRSG. After performing a thorough thermoecnomic analysis, an optimization study is done in view of three approaches. The first and second approaches are single objective optimizations, which utilize two heuristic algorithms, namely, genetic algorithm (GA) and particle swarm optimization (PSO). The first approach is a global optimization problem, which completely optimize the combined system. The second one, as an innovative method, is a local optimization approach, which optimize HRSG and ME-TVC in two separate stages while the third approach is a multi objective optimization. Eventually, the results of the first and second approaches show that the minimum amount of objective function achieved by PSO is better, although the third approach presents a system with higher productivity.     

中国海水淡化工程进展

本文介绍了中国已建成投产海水淡化装置的数量、产量及各种淡化方法所占比例。到目前为止,海水淡化技术主要应用于沿海岛屿和沿海地区电力、化工等企业。随着海水淡化技术的发展和应用规模的扩大,淡化水生产成本将与市政供水价格接近,海水淡化技术将不仅用于沿海岛屿和企业供水,而且将大规模地应用于市政供水。     

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。     

Analysis of water and power costs by various methods,based on Jeddah IV

The Jeddah IV Power and Desalination Plant is the biggest, dual-purpose plant in the world. Moreover, it is perhaps the first plant of this kind for which authentic cost and operational data are available. As such, it provides a reliable means of assessing the present status of desalination technology and its influence on the cost of power and water.The well-known theoretical methods of cost allocation are used in deriving the product cost from the Jeddah IV plant. The influence of local factors and contractual constraints is discussed. Extrapolations are made to determine the projected cost of water on similar plants but with different performance ratios. Recommendations are made on cost optimization and the most favourable combination for dual-purpose power/desalination plants based on steam turbines and MSF process.     

Analysis of water desalination and power generation expansion plans for the Emirate of Abu Dhabi — a preliminary study

This paper contains a comparative economic study of a number of different expansion schedules for power and desalination plants required to meet a forecasted demand in electricity and water for the Emirate of Abu Dhabi. For power generation, steam turbine and gas turbine plants were considered and for desalination both multistage flash distillation and reverse osmosis processes were investigated. Nine combinations of power and desalination plants were selected and a present worth economic analysis was conducted. Capital and operating cost figures used are those typical of the local conditions at Abu Dhabi. Based on the assumptions used in this study the plant combination using steam turbine power plant connected to a reverse osmosis unit seems to represent the most economic alternative.     

Implications of desalination for water resources in China — an economic perspective

China is a country with severe water shortages. Water is becoming scarcer due to population growth, industrialization and urbanization. Recent studies show that by the next 50 years water resources per capita will go down to around 1700 m³, which is the threshold of severe water scarcity. Especially in North China, water shortage has become a critical constraint factor for socioeconomic development in the long run. To solve or eliminate water shortage problems, seawater desalination draws more and more attention as an alternative water supply source. The objective of the study is to assess the potential of desalination as a viable alternate water source for China through analysis of the costs of desalination, the water demand and supply situation as well as water pricing practices in China. Based on the investment costs and estimated operation and maintenance costs, an economic appraisal for the costs of desalination for two main processes, MSF and RO, has been conducted. The study shows that there is a decline of unit cost of desalination over time and the average unit cost of the RO process was lower than that of the MSF process. A unit cost of 0.6 $/m³ for desalting brackish water and 1.0 $/m³ for seawater are suggested to be appropriate for the potential application of desalination in China. Future trends and challenges associated with water shortages and water prices are discussed, leading to conclusions and recommendations regarding the role of desalination as a feasible source of water for the future.     

Optimization in dual purpose plants

The world trend is to save energy and its best use. One of the ways is the dual purpose plant in sea water desalination area, with simultaneous production of desalinated water and electrical power. The combinated production improves the effcieicny of the rhmic cycle and the utilization of fuel is better than separately production.The characteristics of plant such as water/power ratio and the economy ratio will be determined for the dual plants so that the design values must be the optimum point out of all possible values.The optimum relationship water/power and economy will be determinated as a function of the yearly bank rate, the amortization period in years, the fuel cost, the utilization factor, etc. Definitively, the optimum point is a function of the investment cost and the operating cost.The influence on the optimum point of above factors with two possibilities is analyzed : condensation turbine and back pressure turbine.The influence of the fuel cost and labour cost excalation on an installated dual plant and designed at the optimum point is too analyzed.     

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%.     

Optimal design of an electrodialysis brackish water desalination plant

This paper considers the optimal design and operation of electrodialysis (ED) desalination plants. In general an ED plant aims to produce potable water from a high salinity source, like brackish water or high salinity water. The system is modelled mathematically as mixed-integer non-linear programming (MINLP) optimization problem, determining the number of desalination stages, the membrane area, the total required energy so as to minimise the total annualised cost of the investment accounting for both infrastructure and operating costs. Two examples from the literature illustrate the applicability of the proposed approach and evaluate the quality of the results obtained.