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William B Krantz - One of the best experts on this subject based on the ideXlab platform.

  • Energy optimization of a multistage reverse osmosis process for seawater desalination
    Desalination, 2018
    Co-Authors: Goktug M Ahunbay, William B Krantz, Birgul S Tantekinersolmaz
    Abstract:

    Abstract The water Recovery, net specific Energy consumption (SECnet) and osmotic pressure differential (OPD) are determined for a multistage reverse osmosis (MSRO) process relative to conventional and the recently advanced Energy-efficient RO (EERO) processes. The MSRO process combines RO and nanofiltration (NF) stages in series, and blends permeate from the NF stages with the saltwater feed. This increases the water Recovery and lowers the rejections required in the RO stages. The SECnet of the MSRO process to produce water containing ≤ 350 ppm salt is evaluated at the thermodynamic limit for pump and Energy-Recovery-Device efficiencies of 85% and 90%, respectively, which provides a basis of comparison relative to alternative processes. The MSRO process employing one RO and two NF stages in series achieves a 65% water Recovery for a 35,000 ppm seawater feed producing a product water with ≤ 350 ppm salt at an OPD of 51.7 bar and SECnet of 2.688 kWh/m3, reductions of 35% and 8%, respectively, relative to conventional SSRO. For the same conditions, the MSRO process employing two RO and two NF stages in series requires an OPD of 68.0 bar and SECnet of 2.22 kWh/m3, reductions of 14% and 1.6%, respectively, relative to two-stage SSRO.

  • Energy-efficient reverse osmosis desalination process
    Journal of Membrane Science, 2015
    Co-Authors: Tzyy Haur Chong, Siew-leng Loo, William B Krantz
    Abstract:

    A novel Energy-efficient reverse osmosis (EERO) process is proposed for which the retentate from single-stage reverse osmosis (SSRO) serves as the feed to a countercurrent membrane cascade with recycle (CMCR). The 3-stage EERO process employs two, whereas the 4-stage EERO process employs three stages in the CMCR. The EERO process is advantageous because of four features: (i) coupling SSRO with a CMCR; (ii) countercurrent retentate and permeate flow; (iii) permeate recycling; and (iv) retentate self-recycling owing to the use of one or more nanofiltration stages. The EERO process was compared to conventional SSRO for both processes operating at the thermodynamic limit and employing an Energy-Recovery Device. For the same overall Recovery the osmotic pressure differential is reduced by 33% and 50% relative to SSRO for the 3- and 4-stage ERRO processes, respectively. There is a critical Recovery above which the EERO process also can reduce the specific Energy consumption (SEC) relative to SSRO for the same Recovery. For a typical seawater feed of 35g/L the 3-stage EERO process can achieve a 75% Recovery at a net SEC of 2.746kWh/m3, an 11.0% reduction in the SEC relative to SSRO for the same Recovery. The 4-stage EERO process can achieve a 75% Recovery at the same net SEC as SSRO (3.086kWh/m3). Accounting for the additional membrane area required for the EERO process increases its cost relative to that for SSRO by at most 8%. An additional benefit of the EERO process relative to SSRO is the highly concentrated retentate that reduces the brine disposal volume or can be used to greatly increase the draw potential to harvest its osmotic potential Energy via the pressure-retarded osmosis process.

Iqbal M Mujtaba - One of the best experts on this subject based on the ideXlab platform.

  • evaluation and minimisation of Energy consumption in a medium scale reverse osmosis brackish water desalination plant
    Journal of Cleaner Production, 2020
    Co-Authors: Alanood A Alsarayreh, M A Alobaidi, A M Alhroub, Raj Patel, Iqbal M Mujtaba
    Abstract:

    Abstract The Reverse Osmosis (RO) process has been expansively used in water treatment as a result of its low Energy consumption compared to thermal distillation processes, leading to reduced overall water production cost. Evaluation and minimisation of Energy consumption (expressed in kWh/m3 of fresh water production) in a medium-scale spiral wound brackish water RO (BWRO) desalination plant of the Arab Potash Company (APC) are the main aims of this research. The model developed earlier by the authors has been integrated to simulate the process and achieve the main aims. Energy consumption calculations of low salinity BWRO desalination plant, with and without an Energy Recovery Device, have been carried out using the gPROMS software suite. In other words, this research evaluated the impact of adding an Energy Recovery Device on the RO process Energy consumption of the APC, which is introduced for the first time. Also, the effects of several operating conditions of BWRO process include the feed flow rate, pressure and temperature on the performance indicators, which include the Energy consumption and total plant Recovery at different Energy Recovery Device efficiencies, were studied. The simulation results showed that the total Energy consumption could be reduced at low values of feed flow rates and pressures and high values of temperatures. More importantly, there is an opportunity to reduce the total Energy consumption between 47% and 53.8% compared to the one calculated for the original design without an Energy Recovery Device.

  • simulation and optimization of full scale reverse osmosis desalination plant
    Computer-aided chemical engineering, 2010
    Co-Authors: Kamal M Sassi, Iqbal M Mujtaba
    Abstract:

    This paper focuses on steady state performance predictions and optimization of the Reverse Osmosis (RO) process utilizing a set of implicit mathematical equations which are generated by combining solution-diffusion model with film theory approach. The simulation results were compared with operational data which are in good agreement having relative errors of 0.71% and 1.02%, in terms of water Recovery and salt rejection, respectively. The sensitivity of different operating parameters (feed concentration, feed flow rate and feed pressure) and design parameters (number of elements, spacer thickness, length of filament) on the plant performance were also investigated. Finally a non linear optimization framework to minimize specific Energy consumption at fixed product flow rate and quality while optimizing operating variables (feed flow rate, feed pressure) and design parameters (height of feed spacer, length of mesh filament). Reduction in operating costs and Energy consumption up to 50 % can be reached by using pressure exchanger as Energy Recovery Device.

Shichang Wang - One of the best experts on this subject based on the ideXlab platform.

  • investigations on the applicability of hydrostatic bearing technology in a rotary Energy Recovery Device through cfd simulation and validating experiment
    Desalination, 2016
    Co-Authors: Yue Wang, Yuxin Wang, Shichang Wang
    Abstract:

    Abstract Based on the structural characteristics of the rotary Energy Recovery Device, the hydrostatic bearing was established on both sides of the rotor. Effects of the hydrostatic bearing on the resultant force and fluid film thickness were investigated by the methods of computational fluid dynamics simulation and validating experiments. Simulation results indicate that resultant force rises linearly with the increase of both operating pressure and thickness difference between the upper and lower fluid films, indicating that there exists a cooperative function between the upper and lower fluid films which favors for the self-adjustment of film thickness and resuming the rotor to a stable lubrication state when the pressure changes. The circular clearance regarded as fluid restrictor was optimized in order to adjust the fluid film thickness rapidly and the best circular clearance is about 0.03 mm. The experimental results indicate that the practical resistance of the rotor can well be reflected by the changing trend of the experimental rotor speed at operating pressure from 0.1 MPa to 6.0 MPa, and is in good accordance with the theoretical resistance calculated by using the simulation results, verifying that the simulation model was reliable. This study provides an applied structure for improving the frictional state of the rotor and prolonging the working life of the Device.

  • control logic and strategy for emergency condition of piston type Energy Recovery Device
    Desalination, 2014
    Co-Authors: Daiwang Song, Shichang Xu, Zhaocheng Wang, Yue Wang, Shichang Wang
    Abstract:

    Abstract Piston type Energy Recovery Device (ERD) commonly depends upon the concerted actions of magnetic sensors and PLC controller to realize the Energy Recovery function. For ensuring operational stability and flexibility of the Device, signal control mode is basically adopted in the standard PLC controller. However, as a typical emergency condition of the signal control mode, failure of the magnetic sensor may bring on function loss of the mode, which imperils the operational safety of the ERD and even the RO system. So in this paper, an optimized PLC control strategy with fault tolerance module is developed to resolve the possible control problem of piston-type ERD. The experimental results indicate that the optimized PLC control strategy can maintain reliable under simulated emergency condition of magnetic sensor failure.

  • multi objective optimization of reverse osmosis networks by lexicographic optimization and augmented epsilon constraint method
    Desalination, 2014
    Co-Authors: Lixin Xie, Yuxin Wang, Jie Liu, Shichang Wang
    Abstract:

    Abstract This study proposes a multi-objective optimization (MOO) of reverse osmosis (RO) networks for seawater desalination. The membrane transport model takes into consideration of the longitudinal variation of the velocity, the pressure, and the concentration in the membrane modules. The RO network with three type Energy Recovery Device options (pressure exchanger (PX), Hydraulic Turbocharger, and turbine) is introduced. Lexicographic optimization (for calculation of a more effective payoff table) and augmented e-constraint method (to avoid inefficient Pareto solutions) are proposed to solve the MOO problem. A fuzzy decision maker is introduced to derive the most efficient solution among Pareto-optimal solutions. Firstly, different Energy Recovery option studies show that using PX is seen to be the most profitable option. Exergy analysis is used to evaluate the contribution of the equipments in Energy degradation. Secondly, the proposed multi-objective framework simultaneously optimizes the total annualized cost (TAC) and Energy consumption. With the increases of weighting for the main objective function: TAC, the most efficient solution moves to lower TAC direction. Finally, system Recovery rate is added as the third objective function. It is reasonable to stay at the appropriate system Recovery rather than to increase up to its limit and generating high energetic losses.

  • Investigations on characteristics and efficiency of a positive displacement Energy Recovery unit
    Desalination, 2005
    Co-Authors: Yue Wang, Shichang Wang
    Abstract:

    Abstract Energy Recovery Device is now an essential apparatus for SWRO plants, and it can be classified into two categories: the turbine type and the positive displacement PD type. The PD type contributes a higher Energy Recovery efficiency (ERE) (>90%) than the turbine type (50%–75%) and becomes a more promising and competitive technology of the field. The experiment simulates the PD Energy Recovery process under a lower test pressure/HP concentrate pressure (∼0.6 MPa). Mainly, the dynamic characteristics and effect of HP concentrate pressure on the ERE of the unit are inspected and analyzed.

T H Panagiotidis - One of the best experts on this subject based on the ideXlab platform.

  • experimental study of the specific Energy consumption for brackish water desalination by reverse osmosis
    International Journal of Energy Research, 2012
    Co-Authors: S A Avlonitis, D A Avlonitis, T H Panagiotidis
    Abstract:

    SUMMARY The specific Energy consumption (SEC) for brackish water desalination by reverse osmosis membranes was studied experimentally at various operating conditions of feed salt water concentration, temperature, Recovery and applied pressure without an Energy Recovery Device. The results were compared with ideal theoretical values. Low-pressure experiments, corresponding to domestic applications, were performed with a maximum pressure of 8 bar. The Energy consumption at normal operating conditions was assessed with a maximum applied pressure of 18 bar. In either case, the Recovery was kept between 0.3 and 0.8. Deviations between ideal and experimental values of SEC are pronounced and even more so at the lower pressures and the higher salinity concentrations. The present experimental data for brackish water desalination did not indicate an optimum of the SEC, although for a given feed concentration lower values were obtained at higher pressures, temperatures and recoveries. However, an empirical fit of the present data suggests that an economic optimum for the design and operation may exist at pressures up to 20 bar and recoveries up to 50%. Copyright © 2010 John Wiley & Sons, Ltd.

M Y Sulaiman - One of the best experts on this subject based on the ideXlab platform.

  • review of brackish water reverse osmosis bwro system designs
    Renewable & Sustainable Energy Reviews, 2009
    Co-Authors: M A Alghoul, P Poovanaesvaran, Kamaruzzaman Sopian, M Y Sulaiman
    Abstract:

    Brackish water are any water sources with TDS between 1000 and 15Â 000Â mg/L. Brackish water cannot be consumed by us directly due to its high salinity. According to World Health Organization (WHO), water with salinity below 500Â mg/L is acceptable as drinking water. There are quite a large number of research that had been done on BWRO. Each of them has agreed with a common design on optimum BWRO design with a slight modification in order to improve more and make a better BWRO system. BWRO systems which have been tested in real situation agree that the single stage system with module connected to reject water is the most optimum system both economically and environmentally. There is some improvement done to the design by using SWRO membrane at the second stage. This improvement increases Recovery rate to about 83% and reduces boron concentration at the same time. Another design is by using hybrid combination of ultra-low and conventional RO membranes. Hybrid improves permeate quality. It is also possible to create a hybrid array by mixing membrane element types within a pressure vessel itself. Co-operating an efficient module arrangement into a complete BWRO system will reduce Energy consumption. Energy-Recovery Device is a component that must be included in any small or large-scale systems. A small-scale RO system, without Energy Recovery, would typically consume two to three times more Energy. This will be more for large-scale systems. While single stage system with module connected to reject water is preferred by researchers who have done real environment testing, simulation prefers to add another membrane to the reject water of the second module. This system is yet to be tested in real environment to prove its standing.