Brine Recirculation Research Articles

Optimal configuration of low‐grade waste heat driven seawater desalination using data envelopment analysis: A case study of industrial application

AbstractWater supply challenges are caused by population growth, industrialization, as well as the scarcity of freshwater resources. Low‐grade waste heat‐driven seawater desalination technologies may improve the water‐energy nexus issues of desalination systems by different configurations. The data envelopment analysis is used to determine the best final decision to achieve a better comparison of different parameters. The optimal configuration of low‐grade waste heat driven seawater desalination is studied using flue gas waste heat in heat recovery boilers of an industrial oil refinery. Nine different types of multistage flash and multi‐effect distillation (MED) desalination plants have been considered. The results show that the multistage flash brine recirculation may produce more desalinated water while the multi‐effect distillation with three stages (3‐stage MED) has the best payback period. Using 3‐stage MED with a production of approximately 19,630 kg/h of water from 5.3 MW exhaust gas is more suitable for this design. Thus, the proposed strategy guides us toward the best decisions to configure low‐grade waste heat‐driven desalination plants for better design considering rigorous simulations for the plants. Moreover, this framework enables us to consider different criteria of technical, economic, and environmental issues for optimal configuration.

Multipass Nanofiltration for Lithium Separation with High Selectivity and Recovery.

Nanofiltration (NF) is a promising and sustainable process to extract Li+ from brine lakes with high Mg2+/Li+ mass ratios. However, a trade-off between Li/Mg selectivity and Li recovery exists at the process scale, and the Li/Mg selectivity of commercially and lab-made NF membranes in a single-pass NF process is insufficient to achieve the industrially required Li purity. To overcome this challenge, we propose a multipass NF process with brine recirculation to achieve high selectivity without sacrificing Li recovery. We experimentally demonstrate that Li/Mg selectivity of a three-pass NF process with a commercial NF membrane can exceed 1000, despite the compromised Li recovery as a result of co-existing cations. Our theoretical analysis further predicts that a four-pass NF process with brine recirculation can simultaneously achieve an ultrahigh Li/Mg selectivity of over 4500 and a Li recovery of over 95%. This proposed process could potentially facilitate efficient NF-based solute-solute separations of all kinds and contribute to the development of novel membrane-based separation technologies.

Evaluation of Thermophysical Properties and Thermal Performance of Amine-Functionalized Graphene Oxide/Deep Eutectic Solvent Nanofluids as Heat-Transfer Media for Desalination Systems

The study mainly focuses on the synthesis and characterization of amine-functionalized graphene oxide (GO-NH2) nanoparticles. It also reports the thermal properties and stability analysis of deep eutectic solvent (DES)- and GO-NH2- based nanofluids. DES is composed of diphenyl ether as the hydrogen bond acceptor and DL-menthol as the hydrogen bond donor in the molar ratio 1:1. The nanofluid was prepared by a two-step method where two different concentrations of functionalized graphene nanofluids, namely, 0.0033 volume fraction (NF1) and 0.0101 volume fraction (NF2), were reported. XRD and FTIR analyses were used to validate the nanoparticle’s identity. Additionally, the morphology and composition of GO-NH2 nanoparticles were investigated using FESEM, FETEM, EDS, and Raman analyses. After that, the stability of the nanofluids was assessed using ζ potential measurements. The ζ potential measurements revealed increased stability, indicating that no agglomeration occurred in the DES-based nanofluid. Excellent thermal conductivity enhancement was observed at a higher temperature for the GO-NH2 nanofluid. The density and viscosity of the base fluid and nanofluid decreased with an increase in temperature from 25 to 85 °C. Further, the specific heat capacity of the nanofluids also increased with the increase in temperature and volume fractions of the nanofluid. Thermogravimetric analysis was also performed to evaluate the thermal degradation of the nanofluid under a nitrogen atmosphere. The nanofluid was used in brine recirculation multistage flash desalination where the gained output ratio of less than 10 was obtained through ASPEN simulation.

Thermodynamic analysis of the humidification-dehumidification-adsorption (HDHA) desalination process

The process of Air Humidification-Dehumidification (HDH) for water desalination and purification can play an important role in the field of low-carbon water production from non-conventional sources. Our research group presented a novel process scheme consisting of a multiple extraction HDH with vapour adsorption (HDHA) and brine recirculation, able to approximate a closed-air closed-water loop with bottom temperature below the environmental one. This novel work presents the strategy of process optimization through the variance analysis and a mathematical algorithm of thermodynamic balancing adapted to this novel process. The results point out the optimization strategies and allow the literature comparison to show how HDHA can overcome the performances of conventional processes at similar conditions, also reaching acceptable values of second law efficiency. In fact, HDHA can overcome the GOR of similar “balanced” water heated HDH reaching GOR around 10 even at acceptable enthalpy pinch (around 15 kJ kg−1) with three air extractions.

Energy and economic performance assessment of a solar-assisted regenerative vacuum membrane desalination system

Vacuum membrane water desalination is a promising technology for freshwater production with the advantages of low conduction heat loss and mass transfer resistance, compared to other membrane technologies. Such systems can be driven by solar thermal collectors for green water production, yet there is a lack of dynamic system simulations in the literature to comprehensively assess the energy and economic system performance and evaluate the impact of brine recirculation as a method of regeneration, especially under hot desert climates where solar resources are abundant, but freshwater resources are scarce (e.g., the northern coast of Egypt, considered as the case study here). In this study, a dynamic system simulation model is developed in TRNSYS, where a new “Type” is introduced for the vacuum membrane module. Initial sizing of the system with ∼20 % solar fraction resulted in annual average gained output ratio and specific thermal energy consumption of 2.51 and 133.5 kWh/m3, respectively, with levelized cost of water and payback period of 14.7 USD/m3 and 1.53 years, respectively. By increasing the solar collectors’ area from 8 to 16 m2, the levelized cost of water increased by 14.54 %. The storage volume was highly influential on the solar fraction, which increased by 101.39 % as the volume increased from 0.3 to 0.7 m3. Increasing the membrane area from 0.3 to 0.5 m2 increased the gained output ratio by 76.75 % while decreasing the levelized cost of water by 14.79 %. Internal heat regeneration through brine recirculation enhanced the system performance at lower recirculation ratios. Without recirculation, the levelized cost of water increased by 117.41 % and the system met the daily distillate water demand for only 90 days of the year.

Studying a Multi-Stage Flash Brine Recirculation (MSF-BR) System Based on Energy, Exergy and Exergoeconomic Analysis

Due to the lack of natural water resources and high consumption of water in industries, desalination systems are good options to supply water demands, especially in regions with a water crisis. If these wastes are used in thermal desalination cycles, in addition to improving efficiency and reducing energy consumption, the production of environmental pollutants can also be reduced. In this paper, the multi-stage flash brine recirculation (MSF-BR) system of the Abadan refinery is investigated from energy-exergy-exergoeconomic viewpoints. In addition, the effects of top brine temperature (TBT), number of stages and ambient temperature on the performance of the system are evaluated. The results at maximum brine temperature show that with increasing the TBT, the exergy efficiency, gained output ratio (GOR) and distillate water production increase by 34%, 47% and 47%, respectively. It is also found that if the number of stages in the heat rejection section increases to more than six stages, GOR will decrease. The exergoeconomic analysis results reveal that the relative cost difference increases by 94% with an increase in the number of stages. Finally, it is concluded that by using the waste heat of a refinery complex for heating steam to run the desalination system, there is a 9103 $/year cost savings due to energy consumption reduction and 193 × 104 $/year cost savings due to CO2 emission reduction.

Brine minimization in desalination of the geothermal reinjection fluid by pressure-driven membrane separation processes

Brine obtained during water treatment by pressure driven membrane processes remains the major drawback. Therefore, it is of paramount important to find a lasting solution in order to minimize its production by both nanofiltration (NF) and reverse osmosis (RO) membranes. In this study, an experimental study with the aim of brine minimization during membrane desalination of the geothermal reinjection fluid using a mini-pilot scale membrane test system having spiral wound NF and RO membranes was conducted. The membranes employed for this task were TR-NF and BW30-RO membranes. First, studies with different brine to feed ratios of 1:4, 1:3, 1:2 and 2:3 represented as NF-F2, NF-F3, NF-F4 and NF-F5, respectively were investigated using TR-NF membrane. A control study with no brine recirculation was conducted as well in order to check the effect of brine recirculation on the membrane performance. Secondly, studies with BW30-RO membrane using same brine to feed ratios as in the case of NF membrane studies were carried out. An applied pressure of 15 bar, initial water recovery of 60% and 4 h of experimental time were employed as operational conditions for both NF and RO membrane studies. Based on the results obtained, it was found that the brine recirculation (with a brine to fresh feed ratio of 2:3) has a significant impact on the permeate flux. The product water can be utilized for the agricultural irrigation purposes. Nevertheless, the boron concentration in the product water was still high for the sensitive crops.

Performance of dual multistage flashing - recycled brine and solar power plant, in the framework of the water-energy nexus

Water is an essential source for life, and due to rapid growth in the population, the demand for clean water is increasing, while the freshwater reservoirs and aquifers are continuously depleting, creating water scarcity. By using desalination techniques, ocean water can be converted into useable water. In this study, a Multistage flashing- Brine recirculation (MSF-BR) model is used as a technique to produce desalinated water. A mathematical model is developed to investigate the performance ratio of the MSF plant driven by solar energy by using a poly PV array type. This solar power plant can provide 6.52 kg/s superheated steam for the system of thermal desalination. The solar power plant is made up of 72 poly-Si panels with 34 strings each. This facility has a capacity of 30 MW; 15 MW is utilized to produce 6.52 kg/s of superheated steam, which is used to power the MSF-BR desalination plant, while the rest is fed into the grid. The MSF-BR plant is made up of twenty-four stages, twenty-one of which are in the heat recovery section (HRS) and the remaining three in the heat rejection section, which is designed to be the most efficient. The top brine temperature is 110 C, the distilled water is 63.314 k/s, and the blowdown brine salinity concentration is around 69,439.54 ppm, according to the MSF-BR performance. Also, with a heat transfer area of 14,559.8 m2 for HRS and 1,663.8 m2 for the rejection section and a stage length of 1.37 to 2.648 m from the first to the last stage, the optimum gain was achieved.

Dynamic Modelling and Simulation of a Multistage Flash Desalination System

As the leading thermal desalination method, multistage flash (MSF) desalination plays an important role in obtaining freshwater. Its dynamic modeling and dynamic performance prediction are quite important for the optimal control, real-time optimal operation, maintenance, and fault diagnosis of MSF plants. In this study, a detailed mathematical model of the MSF system, based on the first principle and its treatment strategy, was established to obtain transient performance change quickly. Firstly, the whole MSF system was divided into four parts, which are brine heat exchanger, flashing stage room, mixed and split modulate, and physical parameter modulate. Secondly, based on mass, energy, and momentum conservation laws, the dynamic correlation equations were formulated and then put together for a simultaneous solution. Next, with the established model, the performance of a brine-recirculation (BR)-MSF plant with 16-stage flash chambers was simulated and compared for validation. Finally, with the validated model and the simultaneous solution method, dynamic simulation and analysis were carried out to respond to the dynamic change of feed seawater temperature, feed seawater concentration, recycle stream mass flow rate, and steam temperature. The dynamic response curves of TBT (top brine temperature), BBT (bottom brine temperature), the temperature of flashing brine at previous stages, and distillate mass flow rate at previous stages were obtained, which specifically reflect the dynamic characteristics of the system. The presented dynamic model and its treatment can provide better analysis for the real-time optimal operation and control of the MSF system to achieve lower operational cost and more stable freshwater quality.

Batch counterflow reverse osmosis

High salinity waters (>7 wt%) remain a dominant challenge for reverse osmosis desalination, as the required osmotic pressures can exceed the burst pressure of the membranes. Osmotically assisted processes have been designed to circumvent this challenge, but have reduced efficiencies and extensive requirements for specialty pumps, stages and other equipment. Here, we present the first batch osmotically assisted process, which dramatically reduces the energy needs and required components of past processes. To do so, we develop an improved time-varying model which can capture the time-varying concentration profiles, fully discretized across the membrane module. This new process, batch counterflow reverse osmosis (BCFRO), recirculates the fluid on both sides of a membrane. A double-acting piston tank enables this brine recirculation to increase pressure over time. The combination of the new process with batch reverse osmosis, using the same components, can lead to a second law efficiency of 60% for high recovery of seawater. The analysis includes detailed trade-off mapping of recovery ratio per pass, total water recovery, water flux and pressures. Such an approach would be the best-in-class for higher salinities where the cost of energy is relatively important.

Combined Analysis of Brine Recirculation and Top Brine Temperature in Multistage Flash Distillers

Combined Analysis of Brine Recirculation and Top Brine Temperature in Multistage Flash Distillers

Exergoeconomic and exergoenvironmental analyses and optimization of a new low-CO2 emission energy system based on gasification-solid oxide fuel cell to produce power and freshwater using various fuels

This study proposes a novel biomass gasification-based solid oxide fuel cell (SOFC) integrated with a gas turbine, a thermoelectric generator, a multi-stage flash desalination with brine recirculation unit (MSF-BR), and a CO 2 capture unit for power and freshwater production. Exergoeconomic and exergoenvironmental analyses of using four biomass fuels, namely, municipal solid waste (MSW), wood, paper, and sawdust on the newly proposed system are carried out. Subsequently, the thermodynamic performance, cost, and environmental impact (EI) indicators of the system are investigated under the varying substantial operating parameters for each selected biomass fuel. Then, the system performance is optimized based on the thermodynamic efficiencies, product cost, and EI of the overall system by applying the fast and elitist non-dominated sorting genetic algorithm (NSGA-II). The results exhibit that the highest produced freshwater and output power are achieved by 46.05 m 3 /day, and 228.7 kW for wood and sawdust, respectively, and the lowest levelized CO 2 emission is achieved to be 0.138 ton/MWh for sawdust. Moreover, better total product cost and EI rate of the system are computed to be 2.106 $/h and 14.97 Pts/h, respectively, for MSW. Therefore, MSW is recognized as the best cost and environment-friendly fuel.

Experimental and numerical evaluation of the energy requirement of multi-stage vacuum membrane distillation designs

Although vacuum membrane distillation (VMD) has a high distillate flux, its potential is limited by its high specific heat consumption (SHC). Flat sheet VMD systems recover the brine energy by employing a cascade system to improve the SHC. Hollow fiber VMD systems, however, have not yet been optimized for energy recovery. To overcome this knowledge gap, four multi-stage configurations (with and without brine energy recovery) were investigated via experimentation and through numerical simulations. The results show that having permeate flux promoting conditions, such as high feed temperature or lower vacuum pressure, improves the SHC for VMD configurations without brine recirculation, but have little impact for configurations with brine energy recovery. A Pareto multi-objective optimization showed that the optimized first-stage heating MS-VMD without brine recirculation has the highest SHC (908 kWh/m3) but one of the lowest LCOW (2.37 USD/m3). In contrast, the configuration with the first-stage heating with brine recirculation provided the lowest SHC (585–629 kWh/m3) and an acceptable LCOW (2.27–8.30 USD/m3). This study reveals that the development of MS-VMD represents a promising direction for thermal desalination technologies, particularly for high saline water applications.

Thermodynamic, economic and environmental impact studies on various distillation units integrated with gasification-based multi-generation system: Comparative study and optimization

Abstract This research proposes four scenarios for a multi-generation system to produce power, pasteurized milk, biofuel and fresh water for the northern areas of Iran. In all scenarios, power, pasteurized milk and biofuel are produced by a similar arrangement of a supercritical CO2 (S–CO2) Brayton cycle, a biomass gasifier and a milk pasteurization unit while the portable water is produced by a brine recirculation multi-stage flash (BR-MSF) in scenario 1, by forward, backward and parallel feed schemes of multi-effect distillation (BF, FF and PF-MED) in scenarios 2, 3 and 4, respectively. A comparative study is conducted for the exergy, exergoeconomic and exergoenvironmental performances of all scenarios with various stages and effects using Engineering Equation Software (EES). The optimum performances of all scenarios are found by applying the fast and elitist non-dominated sorting genetic algorithm (NSGA-II) and using linear programming technique for multi-dimensional analysis of preference (LINMAP), technique for order of preference by similarity to ideal solution (TOPSIS) and Shannon entropy decision makers. According to the results, the maximum distillate water with capacity of 400.6 m3/day is obtained for scenario 1 through Shannon entropy method. Moreover, scenario 4 gives the maximum exergy efficiency with a value of 44.16% using LINMAP method and scenario 2 with the lowest total cost and environmental impact (EI) rates of 77.15 $/h and 33.35 mPts/s, respectively obtained from TOPSIS method is the best layout from the economic and EI aspects.

An experimental study of brine recirculation in humidification-dehumidification desalination of seawater

Humidification-dehumidification (HDH) desalination systems can work with highly saline water feed. However, rejected brine volume from HDH systems is a critical issue of brine management these systems that can result in catastrophic environmental impacts. To minimize the rejected brine volume and increase the overall water recovery ratio in the HDH desalination system, a brine recirculation method is implemented by considering a bleeding flow of the concentrated brine stream. This enables the system to work at steady state high salinity feed. Experiments are conducted for feed salinity of range of 10–30% to investigate the method applicabilty. An open-air water-heated HDH desalination system with direct contact dehumidifier is experimentally examined under varied feed salinities to evaluate the viability and thermal performance of the proposed brine recirculation method. An analytical model is presented which can predict flow rates of bleeding and feed seawater at different water production rates. The results indicate that an overall recovery ratio of nearly 88% at a salinity of 30% can be achieved with the implementation of the proposed brine recirculation method. This method can significantly facilitate brine management related issues of HDH desalination systems by minimizing the rejected brine volume.

Off-grid desalination for irrigation in the Jordan Valley

Groundwater resources in many regions of the world are becoming increasingly depleted and salinized. With many aquifers straddling political boundaries, on-going depletion presents both a flash-point for conflict and an opportunity for cooperation. A salient example is that of transboundary groundwater resources in the Jordan Valley. These are shared among Israeli, Jordanian and Palestinian residents. Here we describe a collaborative project aiming to develop a desalination system for use by Palestinian farmers in the West Bank. Students have collaborated across borders in a programme of training and research, in which they have constructed desalination prototypes. These are based on a simple but efficient batch-reverse osmosis (RO) technology that incorporates energy recovery and brine recirculation to achieve 70%–76% recovery and specific energy consumption <1.3 kWh/m 3. The technology can be solar powered with minimal PV footprint. Being built almost entirely from off-the-shelf parts, the system is readily implemented with levels of engineering expertise available in many areas of the world. To test and upscale the technology, and to propagate the knowledge about it, it is being trialled at centres in the UK, Israel and soon in Palestine. It is concluded that the project demonstrates a valuable approach in regions facing transboundary groundwater challenges, and that further learning resources should be developed for free access to foster collaboration across borders.

Sodium Hydroxide Production from Seawater Desalination Brine: Process Design and Energy Efficiency

The ability to increase pH is a crucial need for desalination pretreatment (especially in reverse osmosis) and for other industries, but processes used to raise pH often incur significant emissions and nonrenewable resource use. Alternatively, waste brine from desalination can be used to create sodium hydroxide, via appropriate concentration and purification pretreatment steps, for input into the chlor-alkali process. In this work, an efficient process train (with variations) is developed and modeled for sodium hydroxide production from seawater desalination brine using membrane chlor-alkali electrolysis. The integrated system includes nanofiltration, concentration via evaporation or mechanical vapor compression, chemical softening, further ion-exchange softening, dechlorination, and membrane electrolysis. System productivity, component performance, and energy consumption of the NaOH production process are highlighted, and their dependencies on electrolyzer outlet conditions and brine recirculation are investigated. The analysis of the process also includes assessment of the energy efficiency of major components, estimation of system operating expense and comparison with similar processes. The brine-to-caustic process is shown to be technically feasible while offering several advantages, that is, the reduced environmental impact of desalination through lessened brine discharge, and the increase in the overall water recovery ratio of the reverse osmosis facility. Additionally, best-use conditions are given for producing caustic not only for use within the plant, but also in excess amounts for potential revenue.

Performance evaluation of humidification-dehumidification (HDH) desalination systems with and without heat recovery options: An experimental and theoretical investigation

Humidification dehumidification (HDH) desalination system is a thermal-based desalination technology that is suitable for small-scale water desalination applications. In this paper, we present an experimental and thermodynamic analysis of the energetic performance of two HDH cycles. The HDH cycles considered are the basic open-air open-water (OAOW) cycle and the modified closed-water open-air (CWOA) cycle with the options of brine recirculation. An experimental investigation is performed on the modified cycle to validate the theoretical model that is used to assess the energetic performance of both the basic and modified cycles. The theoretical model is found to be in a good agreement with the experimental data with a maximum percentage deviation of 5% from the experimental data. Furthermore, limiting cases of the system are explored. Within the limiting cases, the modified cycle recorded about 100% improvement in the energy performance over the basic cycle due to heat recovery process associated with the modified cycle. Additionally, a cost analysis was performed to determine the cost of freshwater production by the presented desalination cycles. Results show that the freshwater price varied from 4.10 to 6.55 $/m3 and 0.79 to 2.25 $/m3 for the basic OAOW HDH cycle and the modified CWOA HDH cycle, respectively.

Performance evaluation of a brine-recirculation multistage flash desalination system coupled with nanofluid-based direct absorption solar collector

Abstract A mathematical model for multistage flash (MSF) desalination system with brine recirculation (BR) configuration is developed in this study. The heat source for BR-MSF is chosen to be a nanofluid-based direct absorption solar collector (DASC) for which a numerical model is developed. Both these systems, BR-MSF and DASC are coupled via a counter-flow heat exchanger. The overall performance of the combined system is quantified in terms of gained output ratio (GOR). Moreover, the variation in GOR caused by various influencing parameters such as height (H) and length (L) of solar collector, nanoparticle volume fraction (fv) and incident flux on the collector (q) is studied in detail. The effect of these parameters on the top brine temperature (To) is also discussed. The study shows that DASC can be used as a heat source for BR-MSF system and gives high GOR ranging between 11 and 14 depending on the various operating conditions. This system is also compared with a parabolic trough collector (PTC) based BR-MSF system and it is found that DASC-based BR-MSF system gives higher GOR under identical conditions (relatively 11% higher). The exergy analysis is also presented for this system which shows the irreversibilities associated with various physical processes and components of the overall system and in addition to that exergy efficiency is also calculated for the overall system.

Process analysis of a novel humidification-dehumidification-adsorption (HDHA) desalination method

The desalination through humidification-dehumidification (HDH) presents still a high energy-footprint but shows many unique attributes that pushed a recent revival of R&D for decentralized production of water. In this paper, a novel process scheme consisting of a multiple extraction humidification-dehumidification with vapour adsorption (HDHA) and brine recirculation is analysed. It works with bottom brine temperatures below the coldest heat source and direct recirculation. With respect to the common classification, the process can be considered a closed-air closed-water (CACW) HDH. The study of the degrees of freedom and the mathematical model for the sensitivity analysis are presented. Process simulation showed how to increase the performances above the GOR of 10 with multiple extractions. The basic design of a HDHA producing >30m3day−1 of distilled water, with higher performance (GOR of 7 and a RR of 50%) than the current state-of-the-art, is discussed. Furthermore, the paper reports the process scheme and the mathematical model of the adsorption unit integrated with the HDH, the breakthrough curves and the mass of sorbent needed to carry the novel process. The considerations here presented highlight the key benefits of the new process and bode well for its technological development.