Basic principles of the md process membrane distillation is an emerging nonisothermal membrane process which uses thermal energy in order to provide a vapor phase of volatile molecules present in the feed stream i. Sharif 4 department of chemical engineering technology, college of technological studies, e public authority for. Vacuum membrane distillation vmd is one of method utilized for driving flux in membrane distillation. In these studies the authors observed that water passed through the membrane, while butanediol was retained.
Membrane distillation md is a broad reference that covers specific information on membranes available and methods for md membrane preparation and characterization. Both pv and vmd membranes were prepared using the phase. Salting out of ethanolwater with salt absolutely do not use this to raise the proof of alcohol duration. Performance investigation of oring vacuum membrane. Vacuum membrane distillation for an integrated seawater. Read more membrane distillation md is widely employed in desalination, concentration in food industries, acid manufacturing, removing organic and heavy metals, and treating radioactive. Omniphobic hollowfiber membranes for vacuum membrane. A hydrophobic membrane presents a barrier for the liquid phase, allowing the vapour phase e. A multieffect vacuum membrane distillation system has been evaluated. Commercial scale membrane distillation for solar desalination.
Vacuum membrane distillation vmd is considered a promising solution because of its various advantages. Management of produced water from shale gas production is a global challenge. For optimizing the concentration process, a concept of threshold flux is proposed. The vacuum membrane distillation has greater flux than other forms of membrane distillation, because a differential pressure lies between the vaporliquid interface and the vacuum side.
The configuration of the vacuum air gap membrane distillation system allows for latent heat. It is a rising technology for seawater or brine desalination process. The book offers an introduction to the terminology and fundamental concepts as well. Simultaneous heat and mass transfer occur in this process and, as will be explained later, different md con. The involved simultaneous heat and mass transfer phenomena through the membrane. Membrane distillation is an attractive technology for solarpowered decentralized desalination that has not yet reached commercial breakthrough on a. Vacuum membrane distillation for desalination of ground water. Pdf vacuum membrane distillation vmd process received a great deal of attention by many investigators for its promising applications in many. Though the liquid phase is found after the transported vapor condensation at both. View the article pdf and any associated supplements and figures for a period of 48 hours. The effects of system configuration and operating parameters have been analyzed. The prepared supported and unsupported pvdf membranes were characterized in.
Identification and mitigation of challenges associated with membrane distillation md modeling are very crucial to the applicability of md technology in the industry. Vacuum distillation is distillation performed under reduced pressure, which allows the purification of compounds not readily distilled at ambient pressures or simply to save time or energy. Membrane distillation md is a hybrid of thermal distillation and membrane separation 1. Preparation and characterization of polyvinylidene fluoride. Oct 30, 2018 membrane distillation is an attractive technology for solarpowered decentralized desalination that has not yet reached commercial breakthrough on a large scale. Feb 27, 2016 an introduction to membrane distillation 1. The book offers an introduction to the terminology and fundamental concepts as. Aquasep is ideal for producing potable water in arid areas. It is quite similar to pervaporation, with the only difference. Membrane distillation is an emerging technology currently being researched for improvements in order to make it a more competitive separation process. The process simply consists of a flat sheet hydrophobic micro porous ptfe membrane and diaphragm vacuum pump without a condenser for the water recovery or trap. Research article performance investigation of oring. Dec 06, 2018 herbal aqueous solutions can be concentrated effectively by vacuum membrane distillation but membrane fouling and flux decline are complex issues in such concentration processes. An experimental and theoretical study on separations by vacuum.
Invented in 1960s, membrane distillation is an emerging technology for water treatment attracting more attention since 1980s. Previously, this process was identified as vacuum membrane distillation, but the author of this chapter has recategorized it as pervaporation. Concentration of must through vacuum membrane distillation 1. Vacuum membrane distillation for desalination of ground. Membrane distillation producing high quality water from. The impact of energy price on parameter selection is highlighted. Permeate vapors from the vacuum pump discharge are condensed in a condenser. Vacuum membrane distillation petro sep corporation. Vacuum membrane distillation vmd process received a great deal of attention by many investigators for its promising applications in many engineering areas. Jan 14, 2015 salting out of ethanolwater with salt absolutely do not use this to raise the proof of alcohol duration.
Potable water can be extracted from seawater by using a vacuum membrane distillation process. Membrane distillation md is a separation process where a microporous hydrophobic membrane separates two aqueous solutions at different temperatures. Us20150114818a1 vacuum air gap membrane distillation system. There are four configurations of membrane distillation including air gap membrane distillation agmd, direct contact membrane distillation dcmd, sweep gas membrane distillation sgmd, and vacuum membrane. The influence of some relevant parameters, such as the feed temperature, stirring rate, or downstream pressure on the md flux was studied. In continuous processes, multiple modules in series may be required to achieve the desired degree of separations. The design of the membrane module proved its applicability for achieving a high heat transfer coefficient of the order of 10. Mar 21, 2018 management of produced water from shale gas production is a global challenge.
Download fulltext pdf download fulltext pdf vacuum membrane distillation. Membrane distillation md is a thermally driven separation process in which separation is driven by phase change. Abstract the possibility of producing drinking water from brackish ground water using vacuum membrane distillation vmd process was studied. Pure water vacuum membrane distillation vmd experiments were performed to evaluate the heat and mass transfer boundary layer resistances in a new. Modelling of vacuum membrane distillation jianhua zhanga, junde lib, mikel dukea, manh hoangc, zongli xiec, andrew grothd, chan tund, stephen graya a institute of sustainability and innovation, victoria university, po box 14428, melbourne, victoria 8001, australia b school of engineering and science, victoria university, p. Membrane distillation may be used in many industrial application to remove undesired impurities from water. Vacuum membrane distillation free download as pdf file. The process simply consists of a flat sheet hydrophobic micro porous ptfe memb rane and diaphragm vacuum pump without a condenser for the water recovery or trap. Direct contact membrane distillation dcmd direct contact membrane distillation is the most straightforward form of membrane distillation, consisting of the membrane modules and the respective heat exchangers. A vacuum pump is used to maintain a vacuum on the permeate side of the module. An economic analysis has been performed to obtain the optimal design and operational parameters.
The oring membrane module consists of three opening holes, one for controlling the vacuum on the permeate side and the other two for feed and water recycling to the feed tank, where the. The membrane distillation process constitutes one of the possibilities for a new method for water desalination. Pdf vacuum membrane distillation for desalination of ground. Membrane distillation md is a thermallydriven separation process, in which only vapour molecules transfer through a microporous hydrophobic membrane.
More particularly, this invention relates to a membrane distillation system with multiple cells in which the systems flux is increased due to the temperature and pressure differential within the system. Vacuum membrane distillation vmd is a variation on this process in which the driving pressure difference is increased by lowering the pressure on the vapor side. A flat sheet oring membrane module was designed and specially manufactured to apply vacuum membrane distillation to seawater desalination figure 3. Research article performance investigation of oring vacuum membrane distillation module for water desalination adnanalhathalalanezi, 1 h. Membrane distillation has been developed to stage that commercial applications will become feasible in the near future, aiming at fresh water extraction from seawater.
Vacuum membrane distillation is a membranebased separation process considered here to remove volatile organic compounds from aqueous streams. Pilots tests and bench scale tests over thousand hours, using various configurations of membranes, spacers and condenser materials, have shown the potential of membrane distillation. Membrane distillation membraneprocess development sterlitech. Multistage membrane distillation process mit technology. Air gap membrane distillation agmd air gap membrane distillation is the most energyefficient of our process configurations. Vacuum membrane distillation for an integrated seawater desalination process. State of the art conference paper pdf available may 2015 with 1,162 reads. The hydrophobicity of the membrane prevents mass transfer of the liquid, whereby a gasliquid interface is created. Vacuum membrane distillation an overview sciencedirect topics. Us20150114818a1 vacuum air gap membrane distillation. In vacuum membrane distillation vmd, a saline liquid stream is vaporized and driven across a hydrophobic porous membrane by lowering the pressure on the vapor side of the membrane. On the other hand, solarpowered membrane distillation spmd desalination systems are. Us20153497a1 vacuum membrane distillation vmd using. Md experiments were carried out using a vacuum membrane distillation vmd configuration and employing pure water or chloroformwater binary mixtures as the feed.
This invention relates to a vacuum air gap membrane distillation system for desalination purposes. Pdf vacuum membrane distillation for desalination of. Oct 27, 2017 pdmspvdf microporous membrane with semi. A new oring flat sheet membrane module design was used to investigate the performance of vacuum membrane distillation vmd for water desalination using two commercial polytetrafluoroethylene ptfe and polyvinylidene fluoride pvdf flat sheet hydrophobic membranes. However, lowsurfacetension species in produced water can easily deposit on the membrane surface and cause severe fouling or wetting problems. Preparation and characterization of polyvinylidene. Vacuum membrane distillation vmd is a significant variant of the md process, where the permeation of volatile compound through the. Theoretical and experimental investigation of membrane. Vacuum membrane distillation vmd is a variation on this process in which the driving pressure difference is increased by lowering the pressure on the vapor side of the membrane. The desalinated vapor is condensed and cooled to recover the latent heat of vaporization. Microporous hydrophobic membranes are used to separate the aqueous stream from a gas phase kept under vacuum. The possibility of producing drinking water from brackish ground water using vacuum membrane distillation vmd process was studied.
Department of chemical engineering, changchun university of technology, changchun 012, peoples republic of china. Heat and mass transport in modeling membrane distillation. To solve the problems, an omniphobic polyvinylidene. Membrane distillation is the most efficient onestep separation method. Concentration of fruit juices by vacuum membrane distillation. Several research studies have been carried out on direct contact membrane distillation dcmd modeling because of its simplicity, while other md configurations have gained little attention. In membrane distillation, a heated saline liquid stream is allowed to vaporize through a hydrophobic porous membrane. Four kinds of polypropylene membranes with different diameters of capillaries and pores, as well as wall thicknesses were used in studied.
Read more membrane distillation md is widely employed in desalination, concentration in. Pure water was used as a poreforming additive in the casting solution. Polyvinylidene fluoride pvdf flatsheet membranes were prepared for membrane distillation md. Sterlitech membrane distillation test cells are benchscale crosstangential flow membrane test cells used in temperature driven membrane separation processes. The polymer solutions were cast over a glass plate or over a nonwoven polyester backing material. Two separation processes, pervaporation pv and vacuum membrane distillation vmd, were studied using polyvinylidene fluoride pvdf flat. This technique separates compounds based on differences in boiling. Modern membrane engineering is critical to the development of processintensification strategies and to the stimulation of industrial growth. The degree of separation is controlled by the membrane and fluid proprieties.
The concept of md was first described in technical literature in 1967 2, and numerous researchers around the world have contributed to the understanding of the process 3, 4. Tong qu department of chemical engineering, changchun university of technology, changchun 012, peoples republic of china. Pervaporation and vacuum membrane distillation processes. Thermoeconomic analysis and optimization of a vacuum. This process is briefly discussed in chapter 19, analyzing different configurations air gap membrane distillation, direct contact membrane distillation, vacuum membrane distillation, and sweep gas membrane distillation of the process. Vacuum membrane distillation vmd is an appealing process for separation of aqueous mixtures. Vacuum distillation and low energy desalination youtube. The aspirator generates the vacuum pressure by receiving and passing a circulating liquid and combines the permeate with the circulating liquid such that the permeate condensates in the circulating liquid. Distillation vmd variant can enhance the values of the driving force in this case 26, however, the application of. A vmd system and method uses an aspirator to generate a vacuum pressure for drawing permeate from a membrane module. This multistage vacuum membrane distillation technology has applications in smallscale or offgrid desalination, where it delivers performance and efficiency comparable to existing largescale systems at lower capital cost. Herbal aqueous solutions can be concentrated effectively by vacuum membrane distillation but membrane fouling and flux decline are complex issues in such concentration processes. Vacuum membrane distillation an overview sciencedirect. Thermoeconomic analysis and optimization of a vacuum multi.
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