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.     

核供热堆—多效蒸发海水淡化流程

核供热反应堆技术的发展给海水淡化提供了经济、安全的新热源；核能供热和海水淡化联合系统为解决北方沿海城市供暖与供水提供了很好的途径，带吸收式热的多效蒸发淡化工艺是值得探讨的海水处理工艺流程。     

LTE desalination utilizing waste heat from a nuclear research reactor

Nuclear reactors produce significant amounts of low-quality waste heat which can be utilized for producing high-quality water from seawater by coupling a low-temperature evaporation (LTE) desalination unit. Salient features of the desalination plant, the nuclear research reactor and the waste heat utilization from the reactor are discussed. The scheme of integrating desalination plants with the nuclear research reactors is also presented. This LTE desalination plant utilizing waste heat from a nuclear research reactor will be the first of its kind while demonstrating the safety and economics of nuclear desalination technology as a viable alternative to producing demineralised water from seawater.     

Some investigations on the possibility of using ocean thermal gradient (OTG) for seawater desalination

In tropical areas, there exists a constant temperature gradient of about 20° C throughout the year between warm surface seawater and cold deep water.The use of that temperature difference for electrical energy production has been widely investigated and is well known as OTEC (Ocean Thermal Energy Conversion).Although Open Cycle OTEC plants may produce fresh water as a by-product, when steam is condensed on surface condensers, one may conceive a purely thermal use of Ocean Thermal Gradient (OTG) for seawater desalination, the electrical energy needed for plant operation being produced by conventional means.Plants of 250 to 1 000 cubic meters per day capacity might be designed around desalination modules derived from those proposed for the utilization of low temperature heat rejects. Cold water might be delivered through polyethylene pipes of commercially available diameters.At first main features of OTG desalination are reviewed. Then some technical solutions for desalination modules and cold water pipe are briefly described and preliminary economical evaluations are given.     

华能玉环电厂海水淡化工程设计概述

华能玉环电厂的淡水系统全部采用了世界先进的“双膜法”海水淡化技术,工程投资约2亿元,计划2006年4月30日制出合格的淡水。本文以华能玉环电厂海水淡化工程实例为基础,根据国内外海水淡化发展的新技术以及经验,分析对比了高压泵的选型、能量回收装置的特点,以及回收率确定的几项因素,并根据工程情况分析了制水成本。对缺乏淡水的沿海电厂来说采用海水淡化无疑是一种非常好的选择方案。     

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.     

Prioritizing desalination strategies using multi-criteria decision analysis

Desalination of seawater and brackish water is gaining interest as a viable source of water in several arid countries where conventional water resources are very limited or under stress due to the increasing demands and deteriorating water quality. In Egypt, quite a few large desalination plants exist with capacity over 10,000 m³/day. Most desalination plants are constructed on a small scale to satisfy domestic requirements for small cities and resorts in remote areas. National plans for future desalination facilities should consider different priorities of desalination options considering key factors such as the targeted use of desalinated water, feed water quality, desalination technology, energy source, plants' locations, and their capacities. The objective of this paper is to make a comparison among all the possible desalination alternatives for Egypt, considering key factors involved and using Multi-criteria Decision Analysis (MCDA). Geographic Information Systems (GIS) was utilized along with MCDA to present results of the different desalination alternatives and optional plans at a national scale. The results of this study will direct decision makers concerning the prioritized investments of different desalination options and plans.     

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.     

Electrokinetic desalination of glazed ceramic tiles

Electrokinetic desalination is a method where an applied electric DC field is the driving force for removal of salts from porous building materials. In the present paper, the method is tested in laboratory scale for desalination of single ceramic tiles. In a model system, where a tile was contaminated with NaCl during submersion and subsequently desalinated by the method, the desalination was completed in that the high and problematic initial Cl⁻ concentration was reduced to an unproblematic concentration. Further conductivity measurements showed a very low conductivity in the tile after treatment, indicating that supply of ions from the poultice at the electrodes into the tile was limited. Electroosmotic transport of water was seen when low ionic content was reached. Experiments were also conducted with XVIII-century tiles, which had been removed from Palacio Centeno (Lisbon) during renovation due to damage of the glazing from the presence of salts. These tiles were severely contaminated with both chlorides and nitrates, and one of the tiles also contained sulphates though at a low concentration. The charge transfer was too low in the experiments to obtain full desalination, but promising results were obtained as significant decreases (>81% Cl⁻, ~59% NO₃ ⁻ and ~22% SO₄ ²⁻) were seen.     

Preliminary experimental study of a small reverse osmosiswind-powered desalination plant

The paper describes the work carried out in the development of a small wind-powered desalination plant. Analternative control system was studied to serve as a direct interphase between a reverse osmosis desalination plant and a small wind energy conversion system. The main purpose was to reduce or eliminate the need for an energy storage system (usually, a battery bank). In order to achieve this objective, an experimental prototype of a desalination plant and a wind generator simulator were developed. The systems were evaluated under laboratory-controlled conditions and subjected to field trials. The experimental plant desalinates highly saline seawater (35,000 mg/L) at a rate of approximately 0.4 m³/d. This amount of potable water is sufficient to supply the basic water demands in a small community in an isolated location. The paper also describes the identification of technical problems associated with operating a desalination plant with an intermittent source of energy (wind).     

Preparation and properties of poly(acrylic acid) composite membranes

A new type of membrane has been prepared for hyperfiltration (reverse osmosis) desalination that is essentially a very thin polyelectrolyte membrane. It is prepared by casting an aqueous solution of a polyelectrolyte, specifically poly(acrylic acid) (PAA), directly on one surface of a finely porous support membrane. In hyperfiltration tests, these composite membranes exhibit desalination performance comparable in dilute solutions to that observed with cellulose acetate membranes of the Loeb-Sourirajan type. The water flux through these membranes is linear in the pressure up to 100 atm. Salt rejection is a function of pressure; it is also a function of the concentration of the feed solution and the charge of the counterion, in qualitative agreement with the Donnan ion-exclusion mechanism. Typical long-term results range from water fluxes of 2 × 10^?3 g/cm²-sec (50 gal/ft²-day) and 80% salt rejection to 0.2 × 10^?3 g/cm²-sec (5 gal/ft²-day) and >99.5% salt rejection at 1500 psi with 0.3 wt-% NaCl. These membranes appear to be useful for brackish water desalination.     

Design and construction of 4 × 1440 t/day MSF plants at Brindisi's power station (Italy): Acid / antiscale additive treatment for 100°C top brine temperature.

This paper reports the main parameters of the project, made for ENEL (Italian Electrical Power Government Company), regarding the design and supply of four MSF desalination plants at Brindisi's Power Station.The evaporators will be operated with anti-scale additive but are designed both for sulphuric acid and polymer antiscale treatment to operate at 100°C max. as top brine temperature.The distillate production (60 t/h each unit) will be used as high pressure boiler water make-up, then the distillate, mixed with the condensate coming from each unit, is demineralized by mixed bed ion exchange resin system; for this purpose, three mixed bed units are supplied.The paper reports the main design data, characteristics and materials of the above units.     

膜法海水淡化系统在华能威海电厂的应用

随着我国水资源的日益匮乏,海水淡化技术不断应用于工业中。华能威海电厂三期海水淡化系统设备为笔者所在公司提供,海水作为该厂锅炉补给水水源,采用了超滤(UF)-海水反渗透(SWRO)-一级反渗透-二级反渗透-电去离子技术(EDI)全膜法制备。其中能量回收作为海水淡化系统的重要部分,本文将介绍几种常用的能量回收装置,并详细介绍膜法海水淡化系统在该厂中的应用。     

Solvation-amination-synergy that neutralizes interfacially polymerized membranes for ultrahigh selective nanofiltration

Molecular desalination is broadly used in chemical, food, and textile industries, which needs efficient and anti-fouling separation technologies to reach this goal. Interfacial polymerization is one of the most promising routes to construct ultrahigh selective nanofiltration membranes. However, the irreversible hydrolysis of residual acyl chlorides makes Donnan charges of nascent films distribute unevenly which hinders fine molecular desalination and anti-fouling. Here, we propose a pioneering solvation-amination-synergy strategy to synchronously inhibit the hydrolysis of residual acyl chlorides and promote their amination. The electroneutral nanofiltration membrane with high water permeance (13.2 L m⁻² h⁻¹ bar⁻¹) is quantitatively fabricated that has superb anti-fouling abilities and minimizes Donnan impacts on competitive ion penetrations, so it transmits Na₂SO₄ and NaCl while fully obstructs cationic or anionic dyes (< 500 Da). The ultrahigh molecule to ion selectivities outperform state-of-art nanofiltration membranes, which may provide a paradigm shift for scalable membrane fabrication for various industrial product desalination.     

Hybrid systems in seawater desalination—practical design aspects, present status and development perspectives

Ever since seawater desalination has been applied on an industrial scale, and particular in the countries of the Arabian Gulf, the application of desalination processes in dual-purpose facilities—water and power—as a hybrid configuration has been discussed in many feasibility investigations and also planning concepts. It is above all the combination of reverse osmosis with thermal processes that has found increasing interest with the aim of ensuring, as economically as possible, uniform water supplies under the specific, greatly varying load conditions in the Gulf countries. Such design concepts for hybrid configurations encompass straightforward structures with a low degree of coupling between membrane and thermal desalination processes, but range up to very complex configurations with strong interconnections on both the water side and thermally, as well as with several desalination processes connected in series or in parallel. Classical hybrid concepts in which the permeate from an RO desalination component is mixed with distillate from thermal desalination have already been implemented in Saudi Arabian dual-purpose plants, like Jeddah and Yanbu-Medina. Although hybrid systems of greater complexity have been addressed in many design studies and publications, up to now none has been brought to fruition. Coming into consideration asthe design basis for determining the capacity shares of the various desalination processes operated in a hybrid configuration are: arrangement of thermal cycle of the power plant component; water/power ratio of the dual-purpose seawater desalination and power plant; provision of undiminished water production of the desalination plant as electricity generation varies; provision of a specified drinking water quality with regard to composition and salt content; combination of all these aspects. Also gaining in importance are concerns of environmental pollution and sustainable development when selecting seawater desalination and power plant configurations, as well as their optimization when considering desalination and electricity generation as a whole. In the practical design of hybrid membrane and thermal systems, aspects come to light, though, that restrict linking of the two systems and joint utilization of facilities, as conceived in studies and conceptual design investigations. This applies both for common utilization of intakes and the use of heated up cooling water from thermal processes as a feed stream for the RO part of the desalination process. Additionally, requirements of drinking water composition, particularly chloride content, TDS and compliance with a specific residual content of boron, influence specifically the design of the membrane process part and its share in the total desalination capacity. Such practical aspects have greatly influenced the design and configuration of the Fujairah hybrid plant for which, from a total desalination capacity of 100 MIGD (454,600 m³/d), the share of 37.5 MIGD (170,500 m³/d) makes its seawater RO plant the biggest currently being constructed anywhere in the world. From the findings of the engineering of this plant and the idea that, by increasing interconnection between the two processes on the water side, it is possible to advance a hybrid configuration of this type with regard to cost optimization in the membrane installation, but also by joint utilization of the intake equipment, perspectives result for applied research efforts over the near and long terms, for example: long-term behavior of membranes at elevated temperatures; tendency for biofouling in membrane process with common utilization of cooling water and brine; influences of such interconnections on the overall availability of the facility. But also for the operation and maintenance organization of such large facilities, consequences can be foreseen for the future development of hybrid plants, particularly for operation management and organisation of the interplay of the different power plant and desalination systems, monitoring of SWRO membrane replacement and cleaning, as well as controlling water quality.     

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.     

An ion-exchange process with thermal regeneration XV treatment of sulphite-deoxygenated feedwaters

Under typical plant operating conditions, thermal desalination capacities (TDC) of up to 0.26 meq/ml have been observed for a new range of thermally regenerably resins. The resins are chemically stable when used to desalinate waters containing small amounts of sulphite. With the new “Sirother”¹ resins, deoxygenation by the sulphite technique is a permissible pretreatment option, albeit with some restrictions on the range of feasible desalination flow-schemes.     

Ship-mounted seawater 2500 m3/d flash evaporation plant for Abu Dhabi. economical drinking water for arid regions

Buckau-Walther AG (Krupp Group) handed over a ship-mounted seawater desalination plant to the Water and Electricity Department of the Government of Abu Dhabi on February 16, 1982, in Bremen. This followed a 12-month construction period and two weeks of trials. Named the “Rumaith”, this is the first self-propelled floating seawater desalination plant built for commercial use. The plant, consisting of a self-propelled pontoon-like hull carrying two centrally positioned desalination units of 1250 m³ each, will supply islands, coastal towns and major construction sites in the United Arab Emirates with drinking water and will also be deployed in the event of break-down of stationary desalination plant, to provide an emergency water supply and to alleviate plantation water shortages. After handover, the vessel, accepted by German Lloyd for class + 100 A4K, was pulled by tug to Abu Dhabi in the Arabian Gulf in 40 days. As general contractor, Buckau-Walther AG had the vessel built by a shipyard in Bremen.     

Investigation of water desalination by distillation technique

The information is given on the main large stationary desalination units of different types (evaporating, instantaneous boiling) developed in the USSR and used in the design of the largest plant in Shevchenko having the output of 100000 m³/day of distillate; it operates in close interrelation with an atomic thermoelectric БH-350 fast reactor plant and back pressure turbines. Some results are discussed of constantly performed studies into heat transfer, vapour separation, control of scale deposits and corrosion, search for new thermal systems and instruments to be used for the improvement of operating distillation desalination units and development of new ones. Further prospects of thermal desalination are associated with the use of multi-stage units equipped with horizontally-arranged-tube-film evaporators.     

Performance study of water desalination methods in Saudi Arabia

Saudi Arabia is an arid desert country without rivers or sweet water lakes, however, it does have vast amount of groundwater and seawater. In order to make these waters suitable for human consumption and industrial use, most of their salts must be removed by some means. The desalination methods most frequently used in the Kingdom are: Multistage flash (MSF) evaporation, reverse osmosis (RO), and electrodialysis (ED).During the last decade, we have witnessed a spectacular growth of desalination plants. This growth is expected to continue in the next decade. The present production capacity of all desalting plants in Saudi Arabia is estimated to be 750,000 m³/day; this figure will be most likely tripled in the next five years.This paper is a report on a performance study of the most significant desalination plants in the Kingdom. The plants, which include MSF and seawater and brackish water RO plants, were selected either because of their size or their importance to the desalination technology. The plants are briefly described and their performances are discussed.