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    公开号:NL1038485A
    申请号:NL1038485
    申请日:2010-12-30
    公开日:2012-07-03
    发明作者:Filomeno Arsenio Marchena；Robert Patrick Marlon Wever；Vincentico Roman Junior Vrolijk；Victorino Anthonio Alberts
    申请人:Boekhoudt；
    IPC主号:
    专利说明:

    An innovative environmentally friendly chemical-free osmotic cleaning process for cleaning SWRO and BWRO membranes during operation.
    Description.
    Preface.
    The commercial application of reverse osmosis technology, the Sea Water Reverse Osmosis (SWRO), for the desalination of seawater for the production of drinking water has taken an important place worldwide in recent decades as one of the largest seawater desalination processes. Due to new developments in membrane technology and energy recovery, this process has been further developed into the most energy-efficient desalination process. For the production of high-quality drinking water, permeate of the high-pressure SWRO stage with a concentration of 400-600 ppm of total dissolved salts is further purified in a second low-pressure stage to concentrations of 10-15 ppm of total dissolved salts. This low pressure stage is called the Brackish Water Reverse Osmosis (BWRO).
    A still common problem is the chemical and microbiological contamination of the membrane surfaces despite intensive pre-treatment of the marine water feed. To guarantee stable water production, a chemical cleaning must be carried out regularly. The conventional periodic chemical cleaning consisting of a low pH and a high pH cleaning with alternating rinsing with surface-active chemicals and sometimes a biodispersant is very time-consuming, laborious, costly and environmentally harmful. For dry cleaning, the relevant SWRO-BWRO trains must also be taken out of operation to the detriment of capacity utilization. This description describes an innovative, cost-effective, environmentally-friendly and chemical-free cleaning based on osmotic action with acidified product water for cleaning both the SWRO and BWRO membrane surfaces during operation. The osmotic process is set in motion both by lowering the recovery rate of the SWRO and BWRO trains and by increasing the osmotic pressure of the marine water supply by increasing its salt concentration and temperature.
    The Osmosis process.
    Osmosis is a natural diffusion transport of water through a semi-permeable membrane that separates a concentrated saline solution from pure water or a diluted aqueous solution. Through the higher chemical potential of the pure water or of the diluted solution, water flows through the semipermeable membrane to the concentrated solution until a balance is reached between both solutions at a certain pressure difference, the pressure of the concentrated solution being higher than that of the diluted solution. At this equilibrium pressure difference, the molar free enthalpy, the molar Gibbs energy, of both solutions is equally great and the water transport per unit of time from one solution to another via this semipermeable membrane is equally great.
    The reverse osmosis process.
    In the dynamic osmosis equilibrium process described above, a pressure difference occurs between both solutions separated by the semipermeable membrane, the pressure being higher on the side of the concentrated solution. This pressure difference is called the osmotic pressure of the concentrated solution. At a pressure higher than this osmotic pressure, the reverse osmosis process occurs in which a net transport of pure water takes place via the semipermeable membrane to the side of the diluted solution. This principle is based on the reverse osmosis membrane technology for the desalination of seawater whereby, by applying pressures higher than the osmotic pressure of seawater, the seawater feed is separated via a system of semipermeable membranes into a stream of pure water (permeate) and a stream of brine water with a concentration higher than that of seawater (concentrate). Depending on the salt concentration of the seawater feed, pressures of 60-75 bar must be used for this desalination process.
    For effective water transport, the membrane surfaces must remain clean and free from any chemical and marine biological contamination. In practice, an attempt is made to prevent this by optimum pre-treatment of the seawater feed and by periodic chemical cleaning of the membranes.
    The pretreatment of seawater nutrition.
    For an efficient and effective separation process, the surfaces of the SWRO and BWRO membranes must be free of contamination. The precipitation of chemical components due to over-saturation as a result of polarization concentration and the growth of marine biological organisms can heavily contaminate the surfaces of the membranes and thereby cause an unstable production. Membrane pollution can largely be prevented by intensive pre-treatment of the marine water feed. In this extremely important part of the reverse osmosis desalination process, the physical and chemical pre-treatment of seawater feed is distinguished. The physical pre-treatment consists of the conventional filtration process by applying multi-layer sand filters, micro filter candles and the modern membrane filtration by applying nanofiltration and ultrafiltration. The chemical pre-treatment consists of the use of chemicals to prevent precipitation, coagulants and flocculants to promote the filtration process, continuous or intermediate dosing of disinfectants to prevent microbiological contamination and chemicals for lowering the boron concentration. Despite optimum pre-treatment, in practice contamination of the membranes cannot be completely prevented, which means that periodic chemical cleaning of the membranes is also a necessary important part of the SWRO process.
    Dry cleaning of membranes.
    Preventing contamination of the membrane surfaces is of great importance as described above for maintaining stable operation of the SWRO process. The chemical cleaning of membranes, better known in practice as "Clean In Place" (CLP), is in addition to the pre-treatment of the marine water feed extremely important for cleaning the membranes. The membrane surfaces form a suitable place where the marine microorganisms entering with the pretreated seawater feed can attach and thus form a biofilm. In the literature it is known that micro-organisms occurring in the seawater at rest stage, in the English literature known as the "viable but not cultured" (vbnc) micro-organisms, adhere to the membrane surfaces and due to the rich diet, mainly organic degradation products of the disinfection process, become active and can multiply and thus cause biological contamination.
    The first membrane elements in the SWRO pressure tube in particular are exposed to biological contamination.
    Chemical contamination is caused by precipitation of chemical components due to oversaturation due to the occurrence of polarization concentration as a result of the diffusion process in the interface with the membrane. Alkaline precipitation in particular occurs due to over-saturation of the bicarbonates and carbonates of bivalent cations occurring in marine water nutrition. Due to the increasing salt concentration of the flowing concentrate, especially the rear membrane elements in the SWRO pressure tube are exposed to chemical contamination.
    The membranes in the BWRO section are practically not exposed to micro biological contamination as the feed has been pre-filtered through the SWRO membranes that have a high retention for microorganisms. The higher recovery rate and the high pH for drilling removal do, however, make the BWRO membranes sensitive to the precipitation of alkaline chemical components.
    The periodic chemical cleaning of the SWRO membranes has a frequency of two times a month to three or four times a year, depending on the biofilm formation potential of the seawater feed.
    The chemical cleaning is a laborious and time-consuming process and consists of alternate rinsing of the withdrawn SWRO train with BWRO feed, circulating and soaking with a low pH solution, rinsing with BWRO feed, circulating with an anionic surfactant solution, rinse with BWRO feed, circulate and soak with a high pH solution and rinse with BWRO feed and put it back into operation. The chemical cleaning process can take more than two days and is furthermore, due to the high use of chemicals, a high burden on the environment and quite expensive. As a result, a new innovative chemical-free process has been developed for cleaning the SWRO and BWRO membranes during operation on the basis of the osmosis process for dissolving and loosening the deposits on the membrane surfaces, which is further removed by the concentrate flowing along the membrane surfaces. This entrainment effect is known as the "critical cross flux" effect. The principle of this new membrane cleaning process is based on initiating an osmosis process through the SWRO membranes by lowering the recovery rate and by increasing the temperature and salt concentration of the marine water feed. The membrane cleaning process is further enhanced by using carbon dioxide acidified product water from the curing process of the drinking water for the osmosis process. The BWRO membranes that are mainly contaminated by chemical precipitation are cleaned accordingly by lowering the recovery rate and by rinsing the membranes with acidified product water. This new innovative chemical-free osmotic membrane cleaning process is described in detail below.
    The innovative environmentally-friendly chemical-free osmotic cleaning process for cleaning SWRO and BWRO membranes during operation.
    Desalting seawater using reverse osmosis membrane technology at high pressure has a lot to do with contamination of the membranes. Despite intensive pre-treatment of the marine water feed, chemical and microbiological contamination of the membrane surfaces is practically unavoidable. This pollution is caused by precipitation of the salts of the divalent and trivalent anions and cations present in the seawater. To prevent permanent damage to the membranes, production of water can only continue until a certain pressure difference is achieved over the concentrate side of the membrane, in practice up to a pressure difference of 0.2 bar. Upon reaching this pressure drop, the relevant SWRO-BWRO train must be taken out of operation for the chemical cleaning of the membranes. The repeated chemical cleaning can drastically reduce the service life of the membranes. The conventional periodic chemical cleaning to guarantee stable operational management is, as stated above, very time-consuming, laborious, environmentally harmful and increases production costs.
    In this description an explanation is given of the innovative osmotic membrane cleaning process that is easy to carry out during operation and makes the use of chemicals superfluous. This makes it a cleaning process that does not burden the environment and also saves costs by increasing the capacity utilization of the SWRO-BWRO process and eliminating the intensive use of chemicals.
    The innovative chemical-free osmotic membrane cleaning process is based on lowering the recovery rate of the SWRO and BWRO membranes until virtually no permeate is produced. By lowering the recovery rate, the constant production control system automatically lowers the high pressure of the seawater feed pumps via the variable frequency control.
    A simple process flow diagram of the basic principle of the chemical-free osmotic membrane cleaning process is shown schematically in Figure 1 on page 1/4.
    Figure 1a shows that in normal SWRO operation the seawater feed (1) in the first membrane element (3a) is separated via the semipermeable membrane (5a) into a stream (6a) of pure water (permeate) and a stream ( 4a) of concentrated brine (concentrate). This concentrate stream (4a) is further separated in the successive membrane elements (3b) to (3n) from the SWRO pressure tube (7) via the semipermeable membranes (5b) to (5n) into the concentrated brine streams (4b) to and with (4n) and the pure water streams (6b) to (6n). A number of 7 to 8 membrane elements are used in a conventional SWRO pressure tube. The purified water (8a-8n) produced in the membrane elements is collected in the permeate collection tube (2) of the membrane elements and discharged as permeate flow (8) to a buffer tank or collection line (not shown in figure la). The concentrate stream 4 is discharged in a conventional SWRO to the high pressure section of an energy recovery system for pressure exchange with the seawater feed. Figure 1b schematically shows the basic principle of the innovative chemical-free membrane cleaning process. In this process, the "recovery rate" of the SWRO production unit is simply reduced until the operating pressure equals the osmotic pressure of seawater feed (1). In this situation the dynamic osmosis equilibrium prevails, whereby there is no longer any net transport of pure water (6a) in the direction of the concentrate flow (4a) via the semipermeable membrane (5a) in the membrane element (3a) to the permeate flow (8a) in the collection tube (2). With a further reduction of the recovery rate, corresponding to a pressure reduction of the seawater feed (1), the natural osmosis process dominates and a net diffusion transport of purified water (6a) from the permeate flow (8a) enters the permeate collection tube (2) from the membrane element (3a) to the concentrate stream (4a) to standing. Due to this osmotic water flow, the polarization concentration is canceled and the contaminants deposited on the membrane surface can be torn away from the membrane surface by the transverse flow of pure water (6a), thereby removing the removal of these materials by entrainment with concentrate (4a) flowing along the membrane surface promoted. By further refreshing the permeate stream with a portion of the carbonated product water (9) of the drinking water curing process, an osmosis diffusion transport of acidified water (6a) now occurs via the semipermeable membrane (5a). Acidified water promotes the removal of the chemical and microbiological contaminants present on the membrane surface by the good solubility of alkaline precipitation in acidified water and by changing the osmoregulation process of the microorganisms whereby the salt balance of the cells is disturbed. Solution of the alkaline precipitate and swelling of the microorganisms facilitates the removal process of the impurities from the membrane surface and entrainment with the concentrate stream (4a). This process occurs accordingly in all successive membrane elements (3b-3n) of the SWRO pressure tube (7). This removal process is shown schematically in Figure 1c. In this figure 3c it can be seen that due to the osmosis transverse current (2) coming from the permeate current (3) the microorganisms and the chemical precipitation from the surface of the semipermeable membrane (7) are torn away. As a result of this upwardly directed force and the thrust of the concentrate stream (4), a resultant force (6) acts in the flow direction of the concentrate stream (4) on the swollen micro-organisms (1) which have been detached from the membrane surface (7) and the chemical precipitate (1). 5) thus producing the entrainment effect.
    The cleaning process of the BWRO membranes is accordingly the SWRO membrane cleaning process described above. However, it should also be noted that due to the high quality of the BWRO feed (SWRO permeate), the contamination of the BWRO membranes consists predominantly of alkaline chemical precipitation and as a result it is initially sufficient to simply rinse the membrane concentrate side with acidified product water.
    The osmotic pressure of a saline solution such as seawater is directly proportional to the salt concentration and the temperature of the solution. By increasing the salt concentration and the temperature of the seawater feed, the osmotic pressure of the seawater feed can therefore be increased. By applying this, a reduction in the "recovery rate" of the SWRO can be minimized and the membrane cleaning process can be carried out practically in operation. A simple process diagram of this membrane cleaning process is shown schematically in Figure 2 on page 2/4.
    Figure 2 shows a schematic representation of a two-stage reverse osmosis desalination process consisting of a high-pressure SWRO process step (7) and a low-pressure BWRO process step (12). In the two-stage SWRO-BWRO production process, the pre-treated seawater stream (1) is brought to the required operating pressure for the high-pressure SWRO process step (7) by the high-pressure pump (5). Figure 2 does not show the intake and pre-treatment process of the seawater feed (1) for the sake of simplicity. A portion of the pretreated seawater stream (1a) is directed to the low pressure portion of the energy recovery system (3), a "pressure exchanger", where, through pressure exchange with the concentrate stream (8), it enters the high-pressure SWRO stage (7) and further is brought to the desired operating pressure by the booster pump (6). In the high-pressure SWRO process step (7), the seawater feed (2) brought to the operating pressure is separated by diffusion of purified water (in Figure 2 this reverse osmosis water diffusion is not shown for the sake of simplicity) via the semipermeable membrane (7a) into a concentrate stream (7d) and permeate stream (9) collected in the permeate collection tube (7b). The permeate stream (9) is fed to the collection line or a buffer storage tank (10) of the BWRO feed water (11). In the low pressure BWRO process step (12), the feed water stream (11) due to diffusion of pure water, (for the sake of simplicity this reverse osmosis water diffusion is not shown in Figure 2), is separated into a concentrate stream (12d) via the semipermeable membrane (12a) and a stream of pure water of high quality product water (14) that is collected in the permeate collection line (12b). To increase efficiency, the BWRO concentrate stream (13) is directed to the low pressure portion of the energy recovery system (3). The product water (14) is acidified with carbon dioxide gas (15) for the hardening process of the drinking water and is then led to the collection line and / or buffer storage tank (16) of the product water (17). The acidified product water (17) is led from the product water collection line (16) to the drinking water collection system (19). After the curing system, the drinking water (20) is drained to the drinking water storage tanks after any further treatment required. However, these are not shown in Figure 2 for simplicity. The production of drinking water described above continues until chemical and microbiological contamination of the membranes reaches the permitted increase in the operating pressure and / or the pressure difference across the concentrate side of the SWRO membranes (7a) and that of the BWRO membranes (12a). The relevant SWRO and BWRO trains must then be taken out of operation for the periodic cleaning of the membranes. In this innovative osmotic membrane cleaning process, after lowering the recovery rate of the high pressure SWRO stage (7), the salt concentration of the seawater feed (2) is increased by changing the flow balance of the energy recovery system (3) so that more concentrate ( 8) goes with seawater nutrition (la). This is known as the "lag flow" operating method of the "pressure exchangers", which is not desirable in normal SWRO operations. After increasing the salt concentration, the temperature of this seawater feed (la) can be increased with the electric heating element (4). Normally SWRO membranes can tolerate a temperature of 45 ° C. Increasing the salt concentration and the temperature of the seawater feed (2) increases the osmotic pressure so that the operating pressure is no longer sufficient for water diffusion through reverse osmosis via the semipermeable membrane (7a). The natural osmosis process now occurs on the membrane surface that is in contact with this warm seawater feed with increased salt concentration (7d), whereby permeate (7c) now flows from the permeate collection tube 7b via the semipermeable membrane (7a) to the concentrate stream (7d). In this natural osmotic membrane cleaning process, further lowering the "recovery rate" of SWRO stage (7) can be minimized. However, due to the combination with lowering the recovery rate, the increase in salt concentration and temperature can remain limited. In this new osmotic membrane cleaning process, the chemical and microbiological contaminants that are pressed on the membrane surface by the transverse flow during normal operation can now be torn away from the membrane surface by the reverse transverse flow of the permeate flow (7c) and now more easily by dragging along along the along the flowing concentrate stream (7d) on the membrane surface. In normal operation, BWRO membranes are mainly contaminated by alkaline chemical deposits due to precipitation of carbonates due to the high pH of the BWRO feed water (11). This alkaline precipitate is easily soluble in acidified water. Namely, a solution of sodium hydroxide is dosed to the SWRO seawater feed (2) and to the BWRO feed water (11) for the removal of boron. This is not indicated in Figure 2. For the cleaning of the BWRO membranes (12a) the "recovery rate" is lowered to start the natural osmosis process. In this case, permeate (12 c) now flows from the permeate collection tube (12b) in the reverse direction to the concentrate side (12d) and detaches any precipitates pressed onto the BWRO membranes from the membrane surfaces (12a). The dosing of the sodium hydroxide solution is stopped and the BWRO feed stream (11) is mixed with acidified product water (18) to lower the pH to dissolve the alkaline chemical precipitate. This innovative cleaning process can also be applied preventively over a prescribed period of time to keep the SWRO membrane surfaces (7a) and BWRO membrane surfaces (12a) free from contamination. By using normal SWRO process water for cleaning membranes, the CEP chemical consumption is eliminated. This limits the chemical burden on the environment and delivers a lot of savings on production costs. The design of the SWRO process can be simplified by omitting the CIP system with associated installation for neutralizing the CIP currents for discharge into the sea. Preventive cleaning of the membranes without chemicals and being able to clean the membranes during operation increase the service life and usage time of the membranes and the availability of the SWRO-BWRO production unit.
    This increases the effectiveness and efficiency of the SWRO-BWRO desalination process.
    The only additional energy consumption is heating the part of the seawater supply (1a) with the heating element (4). Also note that this energy consumption can be optimized with the reduction of the "recovery rate" and the increase of the salt concentration. An alternative to the above-described osmotic membrane cleaning process with the intention of minimizing and / or eliminating the use of the electric heating element (4) and to further enhance the osmotic membrane cleaning process by refreshing the reverse permeate currents (7c) and (12c) with acidified product water is shown in page 3 on page 3/4.
    Figure 3 shows that the SWRO-BWRO desalination process is essentially the same as the desalination process schematically shown in Figure 2. However, the difference consists in that a partial flow (8b) of the concentrate flow (8) from the high-pressure SWRO stage (7) after energy exchange in the energy recovery system (3) is led to a solar pond (23). In the solar pond ("solar pond"), sun energy is converted into heat and stored in the soil fluid layers. The liquid in the bottom layers also has a higher concentration and a higher temperature than the top layers. Temperatures of 26-82 ° C can be achieved. The carbonate salts of the concentrate stream (8) can precipitate in the soil layers due to the higher temperatures and further concentration and to settle on the soil.
    For the new innovative osmotic membrane cleaning process of the SWRO membranes (7a), as shown in Figure 3, a warm concentrated salt solution (24) from the solar pond is mixed with the sea water feed (la) to transfer the osmotic pressure from the sea water feed (2) to increase the high pressure SWRO stage (7). This warm concentrated salt solution (24) is purified in the micro filter candles (22) from any co-flowing precipitated salt particles. By lowering the recovery rate and the high osmotic pressure of the warm seawater feed (2) with increased salt concentration, the normal working pressure of the high pressure SWRO stage (7) is no longer sufficient to reverse the reverse osmosis process via the semipermeable membranes (7a). At places where the membrane surface comes into contact with the warm concentrated concentrate stream (7d), the natural osmosis process starts to occur and now a net permeate stream (7c) is found from the permeate collection tube (7b) by diffusion through the membranes (7a) to the concentrate stream (7c). To promote the removal of the contaminants, the permeate stream (7d) in the SWRO stage (7) is refreshed with carbonated product water (18a) in the permeate collection line (7b) of the high-pressure SWRO process step (7). This acid permeate stream (7c) also prevents the precipitation of carbonates in the concentrate stream (7d). The osmotic membrane cleaning process of the BWRO membranes is the same as the membrane cleaning process of Figure 2 with the proviso that the cleaning is further promoted by refreshing the permeate stream (12c) with acidified product water (18b). The alkaline precipitate is dissolved directly in the interface between the membrane surface and the chemical precipitate, which facilitates removal by entrainment. This makes the removal of the chemical precipitate much more effective than the osmotic membrane cleaning process shown in Figure 2 by reducing the operating pressure of the BWRO feed water (11). This osmotic membrane cleaning process can be further optimized by using a solar pond of pure sodium chloride solution. This is intended to prevent possible precipitation of carbonates and other supersaturated salts in the solar pond.
    Figure 4 on page 4/4 shows a schematic representation of this alternative osmotic membrane cleaning process that is substantially exactly the same as the process shown diagrammatically in Figure 3, provided that a sun pond of pure sodium chloride solution is used. A salt pan is used for the natural salt production for the production of the pure salt solution. As can be seen in Figure 4, in this alternative osmotic membrane cleaning process, a portion of the concentrate stream (8a) is passed to a salt pan (22) for the natural production of pure salt. This salt is used for the production of a pure sodium chloride solution for the solar pond (23). For the osmotic membrane cleaning process, the osmotic pressure of the seawater feed (2) of the high pressure SWRO process step (7) is increased by mixing the portion of the seawater feed (1a) with a warm concentrated stream of pure sodium chloride solution (24) from the solar pond (23). In this process the possible precipitation of carbonates in the solar pond, created with the SWRO concentrate (8) as shown in figure 3, is avoided.
    The osmotic membrane cleaning process of the BWRO low pressure stage (12) is analogous to that shown in Figure 3. This osmotic membrane cleaning process makes the reverse osmosis desalination process environmentally friendly and economical with optimum energy consumption.
    Advantages of the new chemical-free osmotic membrane cleaning process.
    - The possibility of reducing the recovery rate in combination with increasing the salt concentration and the temperature of the seawater feed has resulted in a simple effective membrane cleaning process that removes the intensive chemical consumption of the conventional chemical cleaning process of membranes "Clean In Place" (CLP) ).
    - Elimination of the intensive chemical consumption of the conventional CIP process makes this osmotic membrane cleaning process very environmentally friendly.
    - Elimination of the intensive chemical consumption of the conventional CIP increases the service life and the usage time of the membranes. This reduces the replacement costs of the expensive membranes.
    - The possibility of carrying out the osmotic membrane cleaning process in operation increases the availability of the SWRO-BWRO production unit and therefore reduces maintenance costs and production costs.
    The ability to preventively perform this osmotic membrane cleaning process prevents the risk of strong contamination of the membranes and optimizes the average annual energy consumption per cubic meter of water produced.
    - The natural osmosis water transport through the membrane offers the possibility of loosening the contamination pressed onto the membrane surface by the transverse flow during the reverse osmosis process and thereby promotes its removal by entrainment with the concentrate flowing along the membrane surface. This greatly improves the positive removal effect of the design with the "Critical Cross flux" of the membranes.
    The possibility of using the warm concentrated salt solution of a solar pond minimizes and / or eliminates the use of an electric heating element and thereby lowers the electrical energy consumption and makes the osmotic membrane cleaning process economical.
    - The use of a salt pan for the production of a pure sodium chloride solution for the solar pond eliminates the chance of carbonates depositing in the high-temperature liquid layers in a concentrated solar pond.
    The new innovative osmotic membrane cleaning process makes chemical-free cleaning of the BWRO membranes in operation by reducing the recovery rate and mixing the BWRO feed water stream with acidified product water from the drinking water hardening process very simple and economical compared to the conventional chemical membrane cleaning process with external dosing of inorganic and organic chemicals.
    The possibility of refreshing the BWRO permeate with acidified product water from the drinking water hardening process makes the BWRO osmotic membrane cleaning process even more effective.
    In this new osmotic membrane cleaning system, only the process streams associated with the SWRO production process are used and an additional CIP system with associated CEP process streams is superfluous.
    - Conventional SWRO-BWRO production units can easily be converted with minor modifications for the application of the new chemical-free osmotic membrane cleaning system.
    权利要求:
    Claims (16)
    [1]
    1. The principle of the innovative osmotic chemical-free membrane cleaning process for cleaning SWRO and BWRO membranes during operation, as shown in Figure 1b on page 1/4, is based on lowering the recovery rate of the high-pressure SWRO process step until the operating pressure equals the osmotic pressure of seawater feed (1). In this situation, the dynamic osmosis equilibrium between the concentrate streams (4a-4n) and the permeate streams (8a-8n) in the membrane elements (3a-3n). Upon further reduction of the recovery rate, the natural osmosis process dominates and a net diffusion transport of purified water (6a-6n) from the permeate streams (8a-8n) in the permeate collection tube (2) from the membrane elements (3a-3n) to the concentrate streams (4a-4n) to standing. By this osmotic water stream, the impurities deposited on the membrane surfaces are released and removed by entraining with the concentrate streams (4a-4n). By changing the permeate stream with carbonated gas acidified water (6), the removal of the chemical and microbiological contaminants present on the membrane surfaces is promoted by the good solubility of alkaline precipitate in acidified water and by changing the osmoregulation process of the microorganisms.
    [2]
    2. The innovative osmotic chemical-free membrane cleaning process for cleaning SWRO and BWRO membranes during operation, as shown in Figure 2 on page 2/4, is an innovative membrane cleaning process based on the osmotic membrane cleaning principle described in claim 1 in which the osmosis process is underway. is set by lowering the recovery rate and increasing the osmotic pressure of the sea water feed (2) by heating the part of the sea water feed (la) with the heating element (4) and increasing its salt concentration by the " lag flow ”operating method of the energy recovery system (3) in which more concentrate (8) goes with the seawater feed (la). The natural osmosis process now occurs on the membrane surfaces that are in contact with this warm seawater feed with increased salt concentration, whereby permeate (7c) flows from the permeate collection tube (7b) via the semipermeable membranes (7a) to the concentrate stream (7d). In this natural osmotic membrane cleaning process, further lowering the "recovery rate" of SWRO stage (7) can be minimized. The combination with the reduction of the "recovery rate" means that the increase in salt concentration and temperature can remain limited. In this new osmotic membrane cleaning process, the chemical and microbiological contaminants can now be lifted from the membrane surfaces by the reverse transverse flow of the permeate stream (7c) and can now be more easily removed by entraining with the concentrate stream (7d) flowing along the membrane surface. The BWRO membranes (12a) are cleaned by lowering the "recovery rate" of the low pressure BWRO process step (12) to initiate the natural osmosis process. In this case, permeate (12c) now flows from the permeate collection tube (12d) in the reverse direction to the concentrate side (12d) and loosens any deposits pressed onto the BWRO membrane surfaces. The dosing of the sodium hydroxide solution for the drilling removal is stopped and the BWRO feed stream (11) is mixed with acidified product water (18) to lower the pH for dissolving the alkaline chemical precipitate.
    [3]
    3. The innovative osmotic chemical-free membrane cleaning process for the operational cleaning of SWRO and BWRO membranes, as shown in Figure 3 on page 3/4, is an innovative osmotic membrane cleaning process that is basically the same as the osmotic membrane cleaning process described in claim 2. . In this alternative, however, the osmotic pressure of the seawater feed (2) is increased by mixing the portion of the seawater feed (1a) with a warm concentrated salt solution (24) from the solar pond (23). A partial flow (8b) of the concentrate flow (8) of the high-pressure SWRO stage (7) is used after salt exchange in the energy recovery system (3) as a saline solution for the solar pond (23). The warm concentrated salt solution (24) is purified in the micro filter candles (22) from any salt particles precipitated in the warm bottom fluid layers of the solar pond (23). To promote the removal of the contaminants, the permeate stream (7d) in the SWRO stage (7) is refreshed with carbonated product water (18a) in the permeate collection line (7b) of the high-pressure SWRO process step (7). The osmotic membrane cleaning process of the BWRO membranes is the same as the osmotic membrane cleaning process described in claim 2, provided that the cleaning is further promoted by refreshing the permeate stream (12c) with acidified product water (18b). The alkaline precipitate is dissolved directly in the membrane precipitation interface, which facilitates removal by entrainment with the concentrate flowing along the membrane surface. This makes the removal of the chemical precipitate much more effective than the osmotic membrane cleaning process of the low pressure BWRO process step (12) described in claim 2.
    [4]
    4. The innovative osmotic chemical-free membrane cleaning process for the operational cleaning of SWRO and BWRO membranes, as shown in Figure 4 on page 4/4, is an innovative osmotic membrane cleaning process that is basically the same as the osmotic membrane cleaning process described in claim 3. However, in this alternative osmotic membrane cleaning process, the osmotic pressure of the seawater feed (2) of the high pressure SWRO process step (7) is increased by mixing the portion of the seawater feed (1a) with a warm concentrated stream of pure sodium chloride solution (24) from the solar pond (23). A portion of the concentrate stream (8a) is discharged to a salt pan (22) for the natural production of pure salt. This salt is used for the production of pure sodium chloride solution for the solar pond (23). In this process, any precipitation of carbonates in the solar pond prepared with the SWRO concentrate (8) as in the osmotic membrane cleaning process described in claim 3 is avoided. The osmotic membrane cleaning system of the BWRO low pressure stage (12) is analogous to the process described in claim 3.
    [5]
    The innovative osmotic chemical-free membrane cleaning processes for cleaning SWRO and BWRO membranes in operation as described in claims 1 to 4 are due to the possibility of reducing the recovery rate in combination with increasing the salt concentration and the temperature of the marine water supply simple effective membrane cleaning processes that eliminate the intensive chemical consumption of the conventional chemical membrane cleaning process “Clean In Place” (CIP).
    [6]
    The innovative osmotic chemical-free membrane cleaning processes for cleaning SWRO and BWRO membranes in operation as described in claims 1 to 4 are very environmentally friendly by eliminating the intensive chemical consumption of the conventional CIP process.
    [7]
    The innovative osmotic chemical-free membrane cleaning processes for the operational cleaning of SWRO and BWRO membranes as described in claims 1 to 4 increase the service life and usage time of the membranes by eliminating the intensive chemical consumption of the conventional CIP. This reduces the replacement costs of the expensive membranes.
    [8]
    The innovative osmotic chemical-free membrane cleaning processes for cleaning SWRO and BWRO in operation as described in claims 1 to 4 increase the availability of the SWRO-BWRO production unit by the ability to perform the osmotic membrane cleaning process in operation. reduce maintenance costs and production costs.
    [9]
    9. The innovative osmotic chemical-free membrane cleaning processes for in-house cleaning of SWRO and BWRO membranes as described in claims 1 to 4 reduce the possibility of strong contamination of the SWRO and BWRO by the possibility of carrying out this osmotic membrane cleaning process preventively. membranes (7a and 12a) and this optimizes the average annual energy consumption per cubic meter of water produced.
    [10]
    The innovative osmotic chemical-free membrane cleaning processes for cleaning SWRO and BWRO membranes in operation as described in claims 1 to 4 make it through natural osmosis water transport (7c and 12c) through transverse flow on membrane surfaces (7a and 12a) during In the reverse osmosis process, contaminants that are pressed down and thereby promote effective removal by entrainment with the concentrate flowing along the membrane surface. This greatly improves the positive removal effect of the design with the "Critical Cross flux" of the membranes.
    [11]
    The innovative osmotic chemical-free membrane cleaning processes for the operational cleaning of SWRO and BWRO membranes as described in claims 3 and 4, by eliminating the possibility of using the warm concentrated salt solution (24) of a solar pond (23) an electric heating element (4) and thereby reduce the electrical energy consumption and make the osmotic membrane cleaning process more economical than the conventional chemical membrane cleaning process.
    [12]
    The innovative osmotic chemical-free membrane cleaning process for the operational cleaning of SWRO and BWRO membranes as described in claim 4 eliminates the possibility of using a salt pan (22) for the production of pure sodium chloride solution for the solar pond (23). precipitation of carbonates in the high-temperature liquid layers in a sun-drenched pond (23) and eliminates the use of micro filter candles (22).
    [13]
    The innovative osmotic chemical-free membrane cleaning processes for cleaning SWRO and BWRO membranes in operation as described in claims 2 to 4 make operationally chemical-free cleaning of the BWRO membranes (12a) by lowering the recovery rate and mixing the BWRO feed water stream (11) with acidified product water (18,19) is very simple and economical compared to the conventional chemical membrane cleaning process with external dosing of inorganic or organic chemicals.
    [14]
    The innovative osmotic chemical-free membrane cleaning processes for cleaning SWRO and BWRO membranes as described in claims 3 and 4 make it possible to refresh the BWRO permeate (12c) with acidified product water (18b) of the drinking water curing process ( 20) the BWRO osmotic membrane cleaning process is even more effective.
    [15]
    The innovative osmotic chemical-free membrane cleaning processes for cleaning SWRO and BWRO membranes in operation as described in claims 1 to 4 only use the process streams associated with the SWRO-BWRO production process and thereby make an additional CIP system with associated CIP system CIP process flows unnecessary.
    [16]
    16. Conventional SWRO-BWRO production units can be converted with minor modifications for the application of the new osmotic chemical-free membrane cleaning process.
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    同族专利:
    公开号 | 公开日
    NL1038485C2|2013-02-18|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    EP0768112A1|1995-10-16|1997-04-16|Christ AG|Process and device for producing pure water|
    EP0899238A1|1997-08-28|1999-03-03|Hager + Elsässer GmbH|Method and apparatus for treating water by reverse osmosis or nanofiltration|
    JP2000079328A|1998-09-07|2000-03-21|Nitto Denko Corp|Cleaning of reverse osmosis membrane module|
    US20040134521A1|2003-01-09|2004-07-15|Boris Liberman|Direct osmosis cleaning|
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    法律状态:
    2014-07-23| V1| Lapsed because of non-payment of the annual fee|Effective date: 20140701 |
    优先权:
    申请号 | 申请日 | 专利标题
    AW01100824|2010-08-10|
    AW01100824|2010-08-10|
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