Seawater Desalination Units Research Articles

Desalination site selection process in the coastal areas with the approach of energy cost reduction (Case study: South of Iran)

ABSTRACT The criteria for selecting a site for the seawater desalination unit are discussed. The technical, economic, social and environmental criteria for installation or construction of suitable sites for desalination units have been investigated. Parameters related to the desalination site selection criteria have been collected; Geographic, environmental data, environmental protection area, topography, atmospherically information, oceanography, existing power plant data, power, and national gas transmission lines, communication lines, land maps, industrial areas and more. In the final section, the target sites on the southern shores in Iran are determined based on the criteria range. Based on the information and considerations of susceptible sites on the South Coast, the process of selecting a seawater desalination site is prepared. Bushehr was selected as the best place for installing water desalination units for the use of a power plant’s transitional gas units.

Development and evaluation of an integrated MED/membrane desalination system

Driving the thermal desalination system by waste heat is typically proposed to save utilized energy and mitigate environmental impact. However, to evaluate the performance of desalination unit, it is necessary to define the exergy efficiency correctly to reveal the real source of irreversibilities. In this regard, a geothermal-based system combined with seawater desalination units to produce distillated water, cooling, power and hydrogen is developed and analyzed thermodynamically. To identify the major extent of generated entropy in multi-effect-desalination (MED) and direct-contact membrane-distillation (DCMD), in addition to exergy destructed in the system's components, the temperature disequilibrium and chemical disequilibrium are taken into account. The present results indicate that the desalination integrated system is capable of producing more than 165,600 kg freshwater per day. Also, under the specific operating conditions, the membrane evaporation efficiency, mass flux through the hydrophobic permeate in DCMD and GOR in MED can be achieved to 46.2%, 9.8 × 10−6 m/s and 5.6, respectively. As well as, the condenser in MED and membrane module in DCMD are the most exergy destructive elements. For MED condenser, it is owned to the large cooling water flow rate and for DCMD, membrane structure like thickness and pore size and also conduction loss are the main reasons of irreversibilities.

Direct integration of a vacuum membrane distillation module within a solar collector for small-scale units adapted to seawater desalination in remote places: Design, modeling & evaluation of a flat-plate equipment

Aiming to design a small-scale compact seawater desalination unit for remote coastal areas or islands, an integrated module coupling vacuum membrane distillation (VMD) and a solar flat-plate collector (FPC) was modeled and studied in the present work, with an extensive description of simultaneous mass and heat transfer for the hybrid solar-VMD module. The VMD model was built both at the scale of the membrane (membrane pore model) and at the scale of the module (feed bulk longitudinal model), and was then coupled with a detailed solar energy model. Effects of various solar and VMD parameters on daily water production, energy consumption and gained output ratio (GOR) were analyzed through several series of simulations. Results showed that without condensation heat recovery, lower operating temperatures were more favorable where a daily water production of 8 kg m−2 of the collector or the membrane area for domestic drinking could be obtained over a 12-h operation. GOR was found to be above 0.7, which is quite comparable to simple-effect single-stage membrane distillation systems driven by indirect supplied heat. Further evaluations also revealed that the introduction of condensation heat recovery facility could markedly improve the daily water production up to 40 kg m−2 for the same operation.

Optimal Number of Effects for Multi Effect Evaporation Seawater Desalination Process Using Solar Thermal Energy-Plate Evaporators

Seawater desalination using Multi effect-plate evaporators and solar energy is one of very promising ways to deal with fresh water shortage and pollution in the same time. Indeed, falling film plate evaporators are becoming more used in the desalination applications. This is because of their multiple advantages compared to tubular evaporators such as high heat transfer rate and low investment cost. This study presents the methodology used for sizing and optimization of plate evaporators for seawater desalination unit using multi effect evaporation and solar thermal energy. The pilot plant unit operates with hot water provided by solar vacuum tubes. The unit was designed for a production capacity of 5 to 7 m3/day of fresh water obtained from evaporation of 28 to 30% of feed seawater. The modeling equations are given at steady-state conditions and they are based on mass, heat balance and heat transfer equations, and thermodynamic and physical properties of each stream. MATLAB programming software is used to resolve the developed algorithm. This work focuses more on studying and analyzing the impact of the number of effects on the total required heat transfer area, the required thermal energy and therefore on the specific cost of water. The obtained results show that it is more beneficial to use nine effects, which gives the key solution for minimizing water production cost. The optimal design shows that the total required heat transfer area of evaporators and the last condenser is approximately equal to 42 m2 and the thermal energy needed to drive the pilot unit is about 64 kW.

Minimizing the total annualized cost of “SIDEM” seawater desalination unit

This work was supported by the Applied Thermodynamics Research Unit (UR 11ES80) and the University of Gabes (Tunisia).

Renewable Energy Supply and Demand for the City of El Gouna, Egypt

The paper discusses a supply and demand scenario using renewable energy sources for the city El Gouna in Egypt as an example for a self-supplying community. All calculations are based on measured meteorological data and real power demand during the year 2013. The modeled energy system consists of a concentrating solar tower plant with thermal storage and low-temperature seawater desalination unit as well as an integrated photovoltaic plant and a wind turbine. The low-temperature desalination unit has been newly developed in order to enable the utilization of waste heat from power conversion processes by improved thermal efficiency. In the study, special attention is given to the surplus power handling generated by the photovoltaic and wind power plant. Surplus power is converted into heat and stored in the thermal storage system of the solar power plant in order to increase the capacity factor. A brief estimation of investment costs have been conducted as well in order to outline the economic performance of the modeled energy and water supply system.

Optimal sizing of stand-alone photovoltaic/wind/hydrogen hybrid system supplying a desalination unit

The real penetration of renewable energy sources (RES) under varying weather conditions required an optimal sizing of hybrid renewable power generation systems. The present paper proposes a methodology based on iterative technique, to perform the optimal sizing of a stand-alone hybrid photovoltaic/wind/hydrogen system supplying a desalination unit which feeds the area’s inhabitants with fresh water. The methodology aims at finding the optimal technical–economic configuration among a set of systems components. Taking into account the models of the main hybrid system components and the hourly meteorological data and load profile for any site located worldwide, the recommended algorithm gives all possible configurations that can completely cover the fresh water requirements of isolated consumers. Afterward, the optimal configuration is predicted on the basis of the minimum initial investment cost. A case study is conducted to analyze a hybrid project, which is designed to supply a seawater desalination unit installed on the Kerkennah islands located in the south of Tunisia.

Developed Design for Line Bleeding Injection Pump: Double-Act LBIP

Injection process is essential for many industrial applications especially in water desalination and water treatment market. The new concept of injection, line bleeding injection pump (LBIP) [8], opens a door for injection processes of simpler and effective injection facilities with relatively low cost and less maintenance requirements. The concept of LBIP is to utilize the pressure inside the line and intensify it to produce higher pressure than the line pressure to inject chemicals inside it. Certain amount of water should be bleed out from the line. The amount of bleed water then could be either recycled back to the line or drained back to the intake. The aim of this study is to develop LBIP design to be double act injection pump. Double-act LBIP design is promising to be more effective and low price design for relatively higher doses injection applications. It has no spring. The developed design will act as two pumps in one unit using very simple design and traditional materials. This concept will take the cost to its minimum value. The double-act LBIP price is promising to be very competitive compared to other injection pump types. Double-act LBIP is equipped with 3 adapters as a simple and accurate variable displacement facility that gives the design a strong potential as metering injection pump with wide range of injection ability (20-1000 liter/day). Both single-act and double-act LBIP designs require no driving power except for the line pressure itself. This concept is promising for researches of developing renewable energy with seawater desalination units in remote areas.

Renewable energy desalination: performance analysis and operating data of existing RES desalination plants

During the last decades, several small autonomous brackish or seawater desalination units driven by renewable energy sources (RES) have been developed within EU and non-EU projects around the world. A significant number of these units were designed, developed, and operated by research centers/universities, in collaboration with companies working in the field of RES and desalination, in their own premises (laboratories) in order to investigate the reliability and performance of the technologies matching in small-scale and autonomous operations. Some systems were also developed for the supply of fresh water to remote areas, and particularly to cover the needs of small villages or communities. Few renewable energy desalination units were installed by RES/desalination market stakeholders as already commercially available products. The present work aims at analyzing the story and operation of selected RES desalination units, representative of a larger number of systems operating all around the world at present. The advantages and disadvantages of the technologies matching, problems encountered, and their solutions, costs, units’ performance as well as the progress of market-available RES desalination packages will also be presented.

An experimental study on small scale sea water desalination unit through solar power in Cox’s Bazar, Bangladesh

An experimental small scale desalination system where solar energy as the main heat source was conducted in a remote area of Cox’s Bazar district of Bangladesh. In this investigation, the performance of three solar stills with transparent glass cover was studied. Treated sea water was given to the solar still and the quantity of distilled water from three solar stills was measured per day and the effectiveness of the stills was compared. The performance of these stills was checked for 20 days. The different parameters i.e. ambient temperature, Salinity, pH, Unionized NH3, Iron, NO2-N, Chlorine, DO and amount of distilled water were studied and analyzed. The average amount of water produced by the still (1) was 455 ml, still (2) was 394.75ml and still (3) was 339.25 ml. The total amount of water produced by the still (1) was 9100 ml, still (2) was 7895 ml and still (3) was 6785 ml. The average desalinated water were obtained 1.06 liter/m2/day, 0.98 liter/ m2/day and 0.95 liter/ m2/day from still 1, 2 and 3 respectively. DOI: http://dx.doi.org/10.3329/jbau.v11i1.18229 J. Bangladesh Agril. Univ. 11(1): 165-170, 2013

Economic Study of Nuclear Seawater Desalination for Mostaganem Site

Algeria has experienced over the past four decades, several periods of drought which led to the use of seawater desalination through a vast program initiated in 2003. The program is implemented to achieve 13 seawater desalination units, to produce 2.3 million m3/day in 2011, to meet needs for potable water, as well as those of small and medium industries in the coastal regions and neighboring regions. This capacity will reach 2.5 million m3/day in 2015, taking into account the tourism development in these regions. Because the program set up is based solely on fossil energy and that desalination technology is a major consumer of energy, to ensure sustainability of water resources and save the energy source (natural gas), it became necessary to initiate prospective studies to replace, for this purpose, fossil energy by other energy sources such as: renewable energy and nuclear energy. Currently, nuclear power is presented as a more attractive solution through the development and technological expertise recorded in the field of nuclear desalination integrated systems. Several demonstration units have been realized which have gained an undeniable know how. The experience accumulated in this area is estimated to 247 reactor-years. For this purpose, a study of nuclear desalination unit is performed for a potential site located in the Western Algerian coast, which is characterized by a very low rainfall rate of 400mm/year. This study is taken in the national context. Indeed, the energy sources outputs that are candidates in this study are based on the Indicative Program of Electricity Generation developed in Algeria. The outputs related to nuclear energy are in respect with the threshold fixed to 10% of the maximum power installed. The definition of nuclear desalination unit capacity is fixed to meet the water demand of the population of this region covering a period of 25 years beyond 2025.The cogeneration option is taken into account in this study. In this study, we present the economic evaluation results of coupling several nuclear reactors with two desalination processes MED and RO, using DEEP3.1 software. These results are compared with those obtained with fossil energy sources based on Natural Gas.

Field test of a solar seawater desalination unit with triple-effect falling film regeneration in northern China

► A new four-stage distillation has been designed, constructed and field tested. ► The field testing had been carried out under the real weather condition for 2 years. ► Annual water production of the system could reach to 250 tons in northern China. ► The cost of water production is estimated approximately 4.6 Dollar/ton for the service life. Based on the mechanism of falling film evaporation condensation, a new four-stage distillation unit with triple-effect regeneration has been designed, constructed and field tested. The seawater desalination system is driven by 80 m 2 all-glass vacuum tube solar collection system with an additional 1 kW wind power system to provide electricity for pumps. The field testing and monitoring of the system had been carried out under the real weather condition for 2 years. The results show that the water production of the system for per unit of solar collector area could reach up to more than 12 kg/m 2 /day under the fine weather conditions. Water production of the system was stable in long period and the annual production could reach to 250 tons in northern China. The economic performance of the system is also discussed. The cost of water production is estimated approximately 4.6 Dollar/ton for the 15-year service life.

Applying the Pareto Principle to Remote Community Seawater Desalination on Torres Strait Islands

On the isolated islands of the Torres Strait, between the tip of Australia and Papua New Guinea, the operation and design of seawater desalination units have evolved since the early 1990s. The Pareto Principle, or 80–20 rule, which infers that 80 percent of the effects result from 20 percent of the causes, best describes the evolution. In the context of small-scale desalination, the implied meaning is that by using a simple, manual desalination system that requires a small amount of operator input, the system can achieve at least 80 percent performance of that expected from a highly monitored and managed system.

Desalination in the Developing World: Tsunami Reconstruction in Maldives

AbstractOn Dec. 26, 2004, the second-largest recorded earthquake caused a series of tsunamis in the Indian Ocean, the effects of which were devastating to the poor, low-lying island nation of Maldives. In response, USAID provided 1.8 million in new programming to benefit two of the largest islands, Hinnavaru and Naifaru. Program objectives included improving health care services by providing a safe, reliable potable water supply utilizing desalination and building local capacity. The project 's technical aspects involved design, installation, and commissioning of two 8,000-gpd seawater desalination units, as well as an open seawater intake system, multimedia filter pretreatment, seawater reverse osmosis units, stabilization and disinfection, brine management, distribution, and emergency energy generation. Project sustainability involved government and local stakeholders, including USAID, three Maldivian government organizations, island chiefs, and local water committees. The lessons learned are particular...

An alternative hybrid concept combining seawater desalination, solar energy and reverse electrodialysis for a sustainable production of sweet water and electrical energy

Fresh water and oil/gas based energy will become scarce since their actual (increase in) consumption rate is definitely unsustainable, when considering their restricted world reserves. Moreover, the large scale burning of such fuels for the production of electrical energy or in industry/transport results in a significant rising of the carbon dioxide concentration in the atmosphere and therefore a rising of global temperatures. Research and development regarding alternative energy sources such as e.g. nuclear fusion is proceeding but mankind also becomes more aware of the sun as being a giant fusion reactor, already at their free disposition and able to act as a lasting and sustainable energy source. The sun in fact delivers continuously about 89,000 TW of usable insolation (photons) power to our planet while the actual global power consumption is about 15 TW. From this point of view, the sun is thus able to provide about 6000 times the world’s energy demand, thus highlighting the enormous potential of solar energy from such numbers in a very obvious way. A major disadvantage of insolation energy of course is its discontinuous and fluctuating availability during daytime. To circumvent such, a solution could eventually be found in the storage of solar power as osmotic energy in highly concentrated salt solutions. The development of salinity gradient power (SGP) based on reverse electrodialysis (SGP-RED) could therefore possibly become an important alternative approach. When combined with classic or solar power based seawater desalination technologies, the resulting hybrid systemcould well be a candidate for the simultaneous production of potable water and electrical energy. The concentration of the brine from the seawater desalination unit (SWDU) could be substantially increased by using solar energy while also producing additional sweet water (condensate). Electricity could then be produced from the mixing energy of the highly concentrated brine and seawater, by using the principle of reverse electrodialysis (RED). In this way the disadvantageous brine waste situation in seawater desalination could eventually be converted into an opportunity regarding the production of a large amount of additional fresh water, a significant amount of electrical energy and an answer to the brine disposal environmental problem. The theoretical simulation results from SGP-RED stack modeling using highly concentrated brine and seawater (brackish water) point to the absolute need of the development of a battery oriented SGP-RED stack configuration, requiring thin ion conductive membranes and thin spacers as to minimize the internal battery resistance and maximize the electrical power output

Economic feasibility of grid-connected PV-RO and PV-MVC small desalination units for remote areas in The United Arab Emirates — A comparative study

This work presents a comparative study between grid-connected photovoltaic-mechanical vapor compression (PV-MVC) and photovoltaic-reverse osmosis (PV-RO) seawater desalination units with a desalted water capacity of 100 m3/d. The two systems are designed to provide water to isolated communities in remote areas in the United Arab Emirates. It is assumed here that transportation of water to those areas is difficult and costly while power from the national grid is available. In this design problem, environmental safety, suitability to demand, simplicity and energy efficiency represent desirable design requirements. Mathematical models are utilized to design the desalination units and produce a preliminary design of the PV array. However, the different design models are not given in this paper. Detailed cost calculations are performed for each one of the suggested systems to assess their feasibility and cost effectiveness. A sensitivity study of water cost to labor cost, cost of electricity, carbon dioxide emission tax and solar panels cost is presented here, together with the computed design characteristics of each one of the two systems. Based on the same cost conditions, the study shows that water cost per cubic meter from the grid connected PV-RO plant is only 51% of the water cost from the grid connected PV-MVC one. The RO plant produced water for a total cost of 3.7 $/m3, while water cost from the MVC plant was 7.29 $/m3.

Salinity gradient power by reverse electrodialysis: effect of model parameters on electrical power output

Salinity gradient power (SGP) is based on the chemical potential difference between concentrated and dilute salt solutions. Reverse electrodialysis (RED) can thus be used to produce electricity by a SGP-RED unit. In principle,a highly concentrated solution can be recovered from a seawater desalination unit (SWDU) and its concentration further increased using solar energy. The SWDU itself can be based on (solar) evaporation, reverse osmosis or other methods. When thus combining a SGP-RED unit, a SWDU and solar energy, a hybrid system can be considered which involves the concentrated salt solution and seawater (/brackish water) as the "dilute" solution. However, key to the sucess of the hybrid concept is an adequate design of the SGP-RED unit. A basic SGP-RED process model has previously been published. This model was expanded by two distinct dilute and concentrate compartment thicknesses and implemented in a solver to investigate the effect of specific parameters. From these simulations, first recommendations have resulted with respect to the design of the SGP-RED unit (membrane and dilute compartment thickness, temperature) and were reported. Final specifications regarding an optimal SGP-RED unit can only be obtained through a dedicated research program. This would enable the evaluation of the overall technical feasibilities releated to the production/performance of thin ion-conductive membranes, an adequate SGP-RED stack design and the experimental verification of the model simulations.

Optimum thermal coupling system for co-generation nuclear desalination plants

Owing to the small number of established nuclear desalination plants worldwide, there is a lack of technical data and not enough practical experience in the field of coupling systems. Therefore, in this study different coupling technologies concerning co-generation systems for linking nuclear power reactors to large thermal seawater desalination units (MED and MSF) are reviewed and optimised. Owing to the attractive and advantageous features of heat pipes, new heat-pipe heat exchangers are proposed for the Intermediate Isolating Loop (IIL), in addition to the previously reviewed types: flash steam chamber and pressurised water loops. All the studied thermal coupling methods are modelled mathematically as heat exchanger loop transfers for the safe transfer of heat energy from nuclear power plant to desalination plant. A methodology for selecting the optimum coupling system is derived, taking into consideration several preference indices, which mainly depend on IIL characteristics: heat transfer surface area, thermal performance and consumed pumping power. As an exploratory case study, these factors are analysed and discussed for the SMART reactor type.

Seawater desalination share among water and market policy changes in Algeria

Algeria suffers significant lack of fresh water since most of its territory is classified as arid and semiarid zones. 90% of the population is concentrated on the northern coastal region which represents 10% of the countries area and situated in a more temperate Mediterranean climate. Many factors intervene in the fresh water crisis availability (growing demand, drought, pollution, etc), the water strategy was depending mainly on rainfall, the use of seawater desalination was confined to industrial needs only (mostly hydrocarbon oils). The state water policy managed by governmental institutions and agencies was based on the construction of dams for rainwater collect. The use of seawater desalination for domestic use started sprouting in early 80's with the increasing drought phenomenon. But actually, the resort to desalination for domestic use has become inevitable. Consequently, the government has put into action an emergency program for the installation of several small seawater desalination units along the coast, in addition to others much important projects. This crisis has come at the time of very important economical changes; these are taking place in the frame of the passage from an entire state managed economy to a market based economy. So new strategies dealing with major issues are being implemented, the governmental institutions are restructured to be managed in market based way. The water market is now open to both national and international private sector.

Performance of MSF desalination plant components over fifteen years at Madinat Yanbu Al-Sinaiyah

The Royal Commission power, desalination and seawater cooling complex at Madinat Yanbu Al-Sinaiyah (MYAS), Saudi Arabia includes six 380 m 3/h multi-stage flash seawater desalination units. Each unit is designated for a top brine temperature of 121°C, employs a decarbonation method using sulfuric acid for scale control, and has a performance ratio of 19 kg of distillate per 1,000 Kcal heat input. The MYAS desalination units have been operated for over 15 years. The units' performance in terms of water production and energy consumption has remained satisfactory, however, various problems have been encountered, resulting in forced outages of varying duration. This paper discusses the performance of various components of the existing units, and highlights problems experienced and countermeasures adopted to eliminate or alleviate the problems. The existing units' operating experience and contemporary trends in the MSF desalination technology have been utilized to avoid similar problems on two new 570 m 3/h units constructed recently. The paper also presents pertinent specifications for the two new units that demonstrate resolution of the problems noted on the existing units.