ES2353194T3 - MEMBRANE ELEMENT IN SPIRAL OF à “SMOSIS REVERSE, MEMBRANE MODULE OF Ó SMOSIS REVERSES USING SUCH ELEMENT AND PROCEDURE INTENDED FOR SEPARATION BY à “SMOSIS INVESTING INTEGRATING THIS MODULE. - Google Patents

Abstract

Reverse osmosis spiral membrane element (10), characterized in that: a plurality of bag-shaped reverse osmosis membranes (2), filtered liquid passage elements (3) disposed inside said reverse osmosis membranes ( 2), and a plurality of feed liquid passage elements (4) interspersed between said reverse osmosis membranes (2) are wound around an outer surface of a hollow tube (1) so that only the interiors of said reverse osmosis membranes (2) communicate with through holes (1a) formed on the surface of said hollow tube (1); each of said feed liquid passage elements (4) is a mesh element having a series of quadrilateral meshes formed by a plurality of linear elements that intersect; two opposite points of convergence (7c, 7d) on four points of convergence (7c, 7d, 7e, 7f) of each of said quadrilateral meshes are adjusted parallel to an axial direction of said hollow tube (1); and the relations 2 mm <= q X <= q 5 mm and X <= q Y <= q 1.8X are satisfied where X designates a distance between said convergence points (7e, 7f) in a direction perpendicular to the axial direction of said hollow tube (1) and Y designates a distance between said convergence points (7c, 7d) in the axial direction of said hollow tube, characterized in that said filtered liquid passage element (3) comprises an element of woven or knitted fabric (8b) of 0.15 to 0.4 mm medium thickness having a plurality of grooves (8a) at least on one of its sides and a liquid permeable fabric element (8c) of 0 , 05 to 0.2 mm of average thickness placed on the grooved surface of said knitting or knitting element (8b).

Description

Osmosis spiral membrane element inverse

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Technical field

The present invention relates to a reverse osmosis spiral membrane element as defined in claim 1 capable of producing filtered water with a small amount of input energy at low cost, a large salt expulsion and high water permeation velocity or water flow rate when applied to desalination of seawater, and it is related to an osmosis membrane module  inverse using the aforementioned element, an apparatus of reverse osmosis separation that incorporates the module, and a method of reverse osmosis separation.

Prior art

A reverse osmosis separation method is a method to obtain filtered liquid that has a low solute concentration by passing a solution through a membrane of reverse osmosis at a pressure higher than its osmotic pressure to thus separate and remove part of a solute. The separation method of reverse osmosis is adopted in technical fields such as desalination of seawater, brackish water desalination, water production Ultrapure, sewage concentration, and recovery of valuables of wastewater.

Especially in the desalination of seawater, the reverse osmosis separation method begins to be used widely since it does not imply a phase change, you need less energy and is easier to control compared to a method of conventional evaporation

To perform the osmosis separation method reverse, a spiral osmosis membrane element is used inverse, for example, whose structure will be described below in Reference to the drawings.

Figure 1 is a schematic sectional view of the perspective of the element, and figure 2 is a cross-sectional view taken along line II-II of the figure one.

The element has a hollow tube 1 arranged in the center of the element and which has a surface of the same formed with a plurality of holes 1a. Reverse osmosis membranes 2, passage elements of filtered liquid 3, and passage elements of feed liquid 4 are wrapped around the outer surface of the hollow tube 1 in a manner described down.

Each reverse osmosis membrane 2 has a similar to a bag as a whole, and a element of filtered liquid passage 3. Osmosis membranes bag-shaped inverse 2 are attached to the outer surface of the hollow tube 1 with its openings 2a wrapping through holes 1a formed in the hollow tube 1 so that the inside of the reverse osmosis membranes 2 and liquid passage elements Filtering 3 can communicate with holes 1a.

Each feed liquid passage element 4 is arranged between reverse osmosis membranes 2 connected each other, and frame elements 5 configured to allow the liquid pass through them, they are connected to both ends of the membrane and the assembly of the passage element, by which Reach the spiral structure.

The item mentioned above is arranged in a pressure vessel and adapts to be supplied at its end (upstream side) with feed liquid 6 to one default pressure.

As the feed liquid 6 flows to length of the feed liquid passage elements 4, experience the separation of reverse osmosis by the membranes of reverse osmosis 2, to be separated in the filtered liquid and a solute The filtered liquid, which passes through the osmosis membranes inverses 2 and which has a low solute concentration, flows through holes 1a and ends in the hollow tube 1. The filtered liquid 6a It is then taken from the downstream side of the element.

The feeding liquid that has not gone through the reverse osmosis membranes 2 continues to flow along the feed liquid passage elements 4 to the side downstream. In the course of the flow, the feed liquid collect the solute separated from the feed liquid and at left on the membrane surfaces, to become concentrated liquid 6b having a high concentration of solute

There is a critical problem in the operation of the element since element performance falls due to the polarization of concentration.

The polarization of concentration is a phenomenon where polluting substances such as impurities and Contaminants contained in the feed liquid are enriched on the surfaces of reverse osmosis membranes 2 that are in contact with liquid passage elements of feed 4, so that the solute and the concentration of substance that contaminates the feed liquid gets older on the membrane surface. Therefore the pressure Osmotic gets taller.

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When the polarization of the concentration, the amount of filtered liquid decreases and impurities as the gel and tartar precipitate on the surface of the membrane. For this reason, the reverse osmosis membrane cannot Develop its capacity and lower the performance of the element.

The polarization event of the concentration can be suppressed by making turbulent the flow of feed liquid on the membrane surface. By example, turbulent flow occurs more easily using the feed liquid passage element 4 of a thicker small to increase the linear velocity of the liquid of feed on the membrane surface, so that the layer of the polarization of the concentration may decrease.

With the liquid passage element of feed 4 having a smaller thickness, however, the step defined by the feed liquid passage element 4 is easily clogs with the contained pollution substances in the feed liquid as impurities and microorganisms. By consequently, the performance of the element decreases and the loss increases of pressure in the feed liquid. To maintain quality and the amount of filtered liquid, the pressure must be reached necessary that operates in the feed liquid, and therefore must provide a high pressure pump that requires energy electrical to handle and press tubes, causing an increase in liquid production costs.

Conventionally, it is widely used a network element that has a network structure as shown in figure 3 as a feed liquid passage element 4, The network element has meshes in the form of series of quadrilaterals formed by linear elements 7a and 7b that intersect one with the other. The network element is arranged between membranes of reverse osmosis 2 and wrap around the hollow tube so that two opposite points of convergence 7c, 7d out of every four points of convergence 7c, 7d, 7e, 7f of the linear elements 7a, 7b are in line in the flow direction of the feed liquid 6, p. eg, in parallel with the axial direction of the hollow tube 1. This kind of network structure is effective by decreasing the concentration polarization, because the feed liquid 6 flowing along the network structure forms a flow Turbulent effectively.

In this conventional network element, the mesh quadrilateral is made in square form, that is the four sides of the quadrilateral mesh have the same length, and the distance (X) between convergence points 7e, 7f is equal to the distance (Y) between convergence points 7c, 7d. The value absolute of an angle? between the line connecting the convergence points 7c, 7d and the linear element (mesh leg) 7a (7b) is 45º.

When the conventional network element that has The size and shape described above is used as an element of liquid feed passage, the flow of liquid from Feeding can become turbulent. However, there is a problem of loss of pressure in the feed liquid increases, of so that the cost of the operation and the cost of the equipment can increase.

The Japanese Provisional Publication of the Patent No. 5-168869 describes a special element of network comprising first linear elements arranged in parallel to the flow direction of the feed liquid and second linear elements that cross the flow direction of the feed liquid at an angle less than 45 °. When this network element is used as a liquid passage element of feeding, loss of pressure in the feed liquid may decrease compared to the network element already mentioned,  but the quality and quantity of filtered liquid decreases. In addition, the effect of decreasing pressure loss produced it is too small to be practical in a speed condition of feed liquid flow in the current operation. In addition, this network element is expensive because it requires a method of advanced network technique. Generally an element of tricot as a passing element of filtered liquid 3, which has one or both sides of it formed with a plurality of grooves at along which the liquid, which has passed through an osmosis membrane Reverse 2, is driven by holes 1a of the hollow tube 1. It shows an example in figure 4.

A filtered liquid passage element 3 of tricot shown in figure 4 has a plurality of grooves parallels 3a formed on one side thereof and is held between reverse osmosis membranes 1, 1. Within the membrane of Reverse osmosis in the form of a bag, the grooves 3a extend to the outer surface of the hollow tube 1 so that the liquid that passes through the reverse osmosis membrane 2 can end up in the tube hollow 1 via grooves 3a.

When the operating pressure is reached of an element comprising the liquid passage elements filtering of this structure, the face of the osmosis membrane inverse 2 that extends over the grooves 3a can deform and partially sink into grooves 3a as indicated by lines Imaginary If this occurs, the reverse osmosis membrane can be damaged by an upper edge of a groove 3a and can lose  your performance. In addition, the cross-sectional area of grooves 3a decreases, and increases the resistance to the flow of filtered liquid, so that the quality and quantity of the filtered liquid decreases.

To eliminate these problems, the use of a filtered liquid passage element shown in the Figure 5 and which has an improved pressure resistance. This step element is comprised of a porous sheet 3c of, by example, polyester interposed between the grooved surface of a tricot element 3 and a reverse osmosis membrane 2, the leaf Porous is formed by 3d holes from 0.05 to 0.1 mm in diameter in spaces of approximately 0.1 to 20 mm.

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With this structure of a filtered liquid passage element, the porous sheet 3c has sufficient rigidity even if it is thin, as long as the holes 3d are small in diameter and the distance between the holes 3d is large. However, the total area per hole becomes small and the resistance to permeating liquid flow is extremely large, so that a great loss of pressure occurs. Thus, element performance cannot be achieved.
enough.

When the total area per hole becomes large to decrease the resistance to the permeating liquid flow, the stiffness of the porous sheet decreases and the porous sheet must have a bigger thickness With porous sheets that are thicker large, the number of reverse osmosis membranes that can being arranged in the membrane element decreases and hence the total decrease of the membrane area. Therefore not a sufficient amount of filtered liquid can be obtained.

As described above, in the element of Reverse osmosis spiral membrane, the passage element of Feed liquid is required to suppress the incidence of the polarization of the concentration on the surface of the membrane without causing pressure loss in the liquid of feeding, and the filtering liquid passage element is required to ensure a desired amount of filtered liquid without increasing the resistance to the flow of the permeating liquid. It will be explained a example of use of the osmosis spiral membrane element inverse in a seawater desalination system.

Figure 6 is a schematic diagram that shows an example of a conventional desalination system of seawater. This system includes, as basic elements, a reverse osmosis membrane module M_ {0} which has, by example, spiral reverse osmosis membrane elements received in a pressure vessel, and a high pressure pump P_ {0} arranged upward on the side of the membrane module of reverse osmosis M_ {0}.

In this system, seawater 6 enters and feeds the high pressure pump P_ {0}, Seawater 6 pressurized by the high pressure pump P0 at a pressure default is fed into module M_ {0}, in module M_ {0}, desalination of seawater continues through the reverse osmosis separation, whereby seawater 6 is separated in filtered water 6a of predetermined water quality and concentrated water 6b. The filtered water 6a is transported to a place where it is used, and concentrated water is expelled. Should note that the desalination process also includes the preliminary treatment for incoming seawater, such as tartar inhibition and sterilization treatment, which is performed to prevent deterioration of reverse osmosis membranes and ensure stable system operation.

In this system, to sufficiently desalinate the seawater that has a salt concentration of, for example, the 3.5%, seawater has to be pressurized by the high pump pressure P_ {0} at a pressure of, the lower, about 5.0 MPa before it is supplied to the module M_ {0}, by doing this, filtered water 6a is obtained from module M_ {0} usually with a recovery rate of approximately 40%, and the proportion of approximately 60% is the concentrated water 6b that It has a salt concentration of approximately 5.8%.

To lower the cost of water production, it is very important to increase the recovery rate of filtered water 6a.

For example, if the operating pressure of the high-pressure pump P 0 in said system is regulated to be approximately 8.0 to 9.0 MPa, the filtered water 6a can be obtained from the seawater that has a salt concentration of approximately 3.5% with a recovery rate of approximately 60%. The proportion of approximately 40% is concentrated water that has a salt concentration of approximately
8.8%

However, when the high pressure pump P_ {0} works at high operating pressure, they occur problems described below.

First, it increases the operating cost of the high pressure pump, and the system needs provision of accessories such as pressure tubes. Therefore, even if the water filtered is obtained with a recovery rate of 60%, the cost Operating the entire system increases. Consequently it is difficult to achieve the objective of reducing the production cost of Water.

Second, when the elements in the module they operate under a high pressure of 8.0 to 9.0 MPa, an effective pressure  too high is used on the side elements towards Up in the module. Therefore, an extremely large amount large water passes through the reverse osmosis membranes, so that membrane surfaces can be easily clogged With pollution substances. In addition, in the elements of side down, on osmosis membrane surfaces inverse adjacent to the liquid passage elements of feed, concentration polarization occurs easily and the scale of tartar precipitates easily. So, the membrane surfaces are easily clogged and increases the loss of pressure In addition, reverse osmosis membranes will easily deform on its sides adjacent to the elements of passage of filtered liquid. Consequently, the loss of pressure increases and the amount of filtered water decreases.

Objectives and Summary of the Invention

An objective of the present invention is to provide a spiral reverse osmosis membrane element which can suppress the decrease in performance caused by the polarization of the concentration on the membrane surface of reverse osmosis, reduce pressure loss even while working at high pressure, get high quality filtered water with a high recovery rate, and that is effective in the desalination of seawater.

Another object of the present invention is to provide a reverse osmosis membrane module that has the previously said reverse osmosis membrane element collected in a pressure vessel.

Another object of the present invention is to provide an apparatus for the separation of reverse osmosis, having the aforementioned osmosis membrane module built-in reverse there, and a working method of apparatus, and above all provide an apparatus for and a method of reverse osmosis separation that can produce filtered water (pure water) of high quality with a high recovery rate with a small power input for operation when Applies to seawater desalination, making it possible lowering the cost of water production compared to an appliance Conventional and method.

Description of the invention

To achieve said objectives, the invention present provides a spiral osmosis membrane element inverse, in which

a plurality of reverse osmosis membranes bag-shaped, filtered liquid passage elements arranged within the reverse osmosis membranes, and a plurality of fluid supply passage elements interposed between the reverse osmosis membranes are wrapped around a outer surface of a hollow tube in a way that only interiors of the reverse osmosis membranes communicate with the holes formed in the surface of the hollow tube;

each of the liquid passage elements of feeding is a mesh element that has series of meshes quadrilaterals formed by a plurality of linear elements that they cross each other;

two opposite points of convergence of four convergence points of each of the quadrilateral meshes are in a straight line in parallel with an axial direction of the tube hole; Y

2 mm ratios ≤ X ≤ 5 mm and X \ leq Y \ leq 1,8X are both satisfied where X indicates a distance between convergence points in one direction perpendicular to the axial direction of the hollow tube and Y indicates a distance between the points of convergence in the axial direction of the hollow tube, where said filtered liquid passage elements they comprise a knitting element or knitting of 0.15 to 0.4 mm of medium thickness that has a plurality of grooves formed on the minus one side of it, and a permeable fabric element of 0.05 to 0.2 mm average thickness placed on the grooved surface of the knitting or knitting element.

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The absolute value of an angle between a line, joining the points of convergence that are in a straight line in the axial direction of the hollow tube, and a mesh leg is within a range of 29 to 45º.

This element is an element with which the operation can be performed at a higher pressure.

The present invention further provides a reverse osmosis membrane module in which at least one element as described above it is arranged in a pressure vessel that it has an inlet for the feed liquid at one end and one outlet to pass the resulting concentrated liquid in the other end of it.

In a reverse osmosis membrane module preferable of the present invention, two or more elements as described above are arranged in the pressure vessel and connected in series with each other.

The present invention further provides a apparatus for separating reverse osmosis, comprising a separation section of the feed liquid comprising the reverse osmosis membrane modules as defined above connected progressively; and liquid feeding media that pressurize arranged on one side up of the section from separation.

In a preferable apparatus for the separation of reverse osmosis according to the present invention, the means of pressurization of the feed liquid is a pump pressurization turbocharger.

The present invention provides, specifically, an apparatus for the separation of reverse osmosis from seawater in which the feed liquid is seawater, the reverse osmosis membrane modules are connected in form of at least two stages, a high electric pump is arranged pressure on one side up between a membrane module of reverse osmosis in a preceding stage, a pump is arranged pressurization turbocharger between the membrane module reverse osmosis in the preceding stage and a membrane module of reverse osmosis at a next stage, and a system is provided of passage to supply the concentrated liquid of the module reverse osmosis membrane in the stage preceding a section of pressurizing turbocharger pump compressor and for diffuse the concentrated liquid of the osmosis membrane module reverse in the next stage to a pump turbine section pressurization turbocharger.

The present invention further provides a reverse osmosis separation method, comprising a step for supply the feed liquid to pressurizing means of the reverse osmosis separation apparatus as defined up and pressurizing the feed liquid, and a step to supply the pressurized feed liquid to the section of separation of the apparatus and separating the feed liquid pressurized in filtered liquid and concentrated liquid.

The present invention provides, in particular, a method of separating water reverse osmosis from sea using an apparatus for the separation of reverse osmosis as defined above in which the membrane modules of reverse osmosis are connected in the form of at least two stages, it it has a high pressure electric pump on one side towards above a one-stage reverse osmosis membrane module above, and a pressurizing turbocharger pump is provided between the reverse osmosis membrane module in the stage precedent and one stage reverse osmosis membrane module next, comprising a first separation step of supply pressurized seawater obtained by operating the high pressure electric pump in the osmosis membrane module inverse in the preceding stage and separating the seawater pressurized in filtered water and concentrated water; a second step of separation supplying the concentrated water produced in the first separation step to the reverse osmosis membrane module in the next stage via a pump compressor section pressurization turbocharger and separating concentrated water also in filtered water and concentrated water; and a step to spread the concentrated water produced in the second separation step at a turbine section of the pressurization turbocharger pump.

The osmosis spiral membrane element Inverse according to the invention has a structure as shown in Figure 1, where each feed liquid passage element 4 is a mesh element as described below.

The feed liquid passage element 4 has a mesh structure as shown in Figure 3 in which a distance X between two opposite convergence points 7e, 7f of four convergence points 7c, 7d, 7e, 7f is of 2 to 5 mm and a distance Y between two other opposite points of convergence 7c, 7d satisfies a relationship
X? Y? 1.8X, the four points of convergence 7c, 7d, 7e, 7f are formed by linear elements 7a, 7b serving as mesh legs. The mesh structure is wrapped around an outer surface of a hollow tube (not shown) so that the convergence points 7c, 7d are in a straight line parallel to the axial direction of the hollow tube, that is to say in parallel with the direction 6 of the feed liquid.

Thus, each quadrilateral mesh formed by linear elements 7a, 7b is in the form of a diamond whose axis more long extends in the flow direction 6 of the liquid of feeding.

In said mesh structure described in the that the convergence points 7c, 7d are in a straight line in parallel with the flow direction of feed liquid, if X it is larger than 5 mm and and consequently it is large, a less turbulent flow over the membrane surface of a reverse osmosis membrane, and therefore, the polarization of the Concentration occurs more easily. On the other hand, if X is smaller than 2 mm and Y is consequently small, the liquid of food flowing along the meshes forms a flow turbulent more easily, and therefore, decreases polarization of the concentration on the membrane surface of a reverse osmosis membrane. However, flow resistance of feeding fluid along the meshes increases, and of there increases the pressure loss produced by operating the element.

In this sense, in the mesh structure of the In the present invention, the distance X is determined to be from 2 to 5 mm, desirably from 2.5 to 4.5 mm, and more desirably from 3 to 4 mm

Respect for the behavior of the liquid of feed 6 flowing along the liquid passage element feed 4 and having a mesh structure, the liquid from feed 6 flows down the side more or less after the linear elements that form the mesh 7a, 7b.

If the feed liquid passage element 4 has meshes (quadrilateral meshes) showing a relationship
X> Y, the feed liquid 6 tends to flow apart from the linear elements 7a, 7b as shown in Figure 7, so that the feed liquid can extend down the side less widely. On the other hand, if the feed liquid passage element 4 has meshes (quadrilateral meshes) that show a relationship
Y> X, the feed liquid 6 flows more after the linear elements 7a, 7b as shown in Figure 8. Therefore, the feed liquid extends more widely on the lower side down.

When the feed liquid spreads more widely on the mesh element towards the lower side down, the feed liquid is supplied more uniformly to the entirety of a reverse osmosis membrane. This also means that the feed liquid mixes more Quickly while flowing. Therefore, the frequency of the polarization of the concentration on the surface of the membrane of a reverse osmosis membrane decreases, and the resistance to the flow of feed liquid decreases.

However, if the liquid passage element of feed 4 has meshes (quadrilateral meshes) showing a ratio Y> 1.8X, the resistance to liquid flow of feeding is too small, and not a turbulent flow but a aerodynamic flow occurs easily on the surface of the membrane of a reverse osmosis membrane. Therefore, the Concentration polarization occurs easily.

In this sense, in the meshes of the present invention, the distances X and Y are determined to satisfy a X ratio ≤ Y ≤ 1.8 X, desirably a 1.1X ratio ≤ Y ≤ 1, 7X, and more desirably a 1, 2X ratio ≤ And ≤ 1.5X.

Therefore, in the mesh structure, the minimum value of an angle (?) between a line that joins the convergence points 7c, 7d and mesh leg 7a (7b) is tan <-1>? = 1 / 1.8 (29 °), and the maximum value thereof is tan <-1>? = 1/1 (45 °). Desirably, the angle (?) is determined to be from 30.5º to 42.5º, and more Desirably to be from 23.5º to 40º.

It is desirable to measure the distance between points of convergence in at least 10 positions (n positions), add the measured values, divide the sum (L) by n, and use the quotient (L / n) as the value of X or Y.

Determining the distance X so that it is within the zone of 2 to 5 mm and the distance Y that satisfies the relationship
X? Y? 1.8X, it is possible that the feed liquid forms an appropriate turbulent flow, whereby the incidence of concentration polarization on the membrane surface is suppressed and the flow resistance of feed liquid increase. Therefore, when the feed liquid having a high solute concentration, for example, is subject to reverse osmosis separation, it is possible to decrease the energy loss due to a loss of pressure in the element and obtain the filtered liquid from high quality.

If the mesh element that has bliss mesh structure described above has a medium thickness smaller than 0.5 mm, the linear velocity of the liquid of feeding on the membrane surface is large and it easily produces turbulent flow. This makes it possible to suppress the incidence of concentration polarization on the Membrane surface of a reverse osmosis membrane. Without However, the pressure loss increases since it is very likely that the passage becomes clogged with the contained pollution substances in the feed liquid.

If the mesh element has a medium thickness larger than 1 mm, the linear velocity of the feed liquid on the surface of the membrane is small, so that the polarization of the store concentration to occur on the Membrane surface of a reverse osmosis membrane.

In this sense, in the present invention, it is desirable to determine the average thickness of the mesh element so that be 0.5 to 1 mm. More desirably, the average thickness is determined to be 0.55 to 0.9 mm, and even more desirably from 0.6 to 0.8 mm.

Here, the average thickness means a value (T / m) obtained by measuring the thickness of the mesh element by at least 10 positions (m positions) using a thickness indicator of precision, adding the measured values, and dividing the sum (T) by m.

Determining the average thickness of the element of mesh that is within said zone, it is possible to provide a element in which the feed liquid has a velocity appropriate linear on the membrane surface so that the incidence of concentration polarization on the membrane surface can be suppressed more effectively, and the passage is prevented from clogging with the substances of pollution so that a rapid increase in the loss of Pressure can be prevented. With this element, the filtered liquid High quality can be obtained in a condition of stable operation for a long period of time.

Even if the average thickness (T / m) of the element of mesh is within the aforementioned range, the linear velocity of the feed liquid on the surface of the membrane cannot be uniform in the event that the element of mesh that has excessive thickness variation so that the respective parts of the feed liquid passage over the Same membrane surface vary in thickness. This is not favorable for the reverse osmosis membrane to develop the uniform performance capacity. It is desirable that a maximum range variable thickness of the mesh element is between the values that they are 0.9 times and 1.1 times the average thickness of the mesh element, respectively.

If the thickness is within said range, the difference in linear velocity of the feed liquid over the membrane surface caused by the difference in thickness of the mesh element is not so large that it can affect the performance capacity of the reverse osmosis membrane. So, the reverse osmosis membrane can fully develop its capacity.

Although the material for the mesh element does not be limited to a special one, the mesh element is made preferably of a material that does not damage the osmosis membrane reverse arranged in contact with the mesh element and from Of which the mesh element can be made at a low price. By example, polyester and polypropylene are materials desirable.

The passage elements of filtered liquid 3 They have a structure as described below. This item can be handled at a higher pressure.

As shown in Figure 9, the element of passage of filtered liquid 8 comprises a tissue or tissue element of point 8b having a plurality of parallel grooves 8a formed at least on one side (in the drawing, only on one side) of the same, and a permeable liquid cloth element 8c disposed on the ribbed surface of the woven fabric element 8b. All the filtered liquid passage element 8 is arranged in a membrane of reverse osmosis in the form of a bag 1, 1.

It is determined that the average thickness of the element of fabric or knitting is from 0.15 to 0.4 mm. Here, the thickness mean means the average of the thickness values of the element of tissue or knitting measured in at least 10 positions using a precision thickness gauge, same as the thickness middle of the feed liquid passage element 4 above mentioned.

If the average thickness is smaller than 0.15 mm, a large number of osmosis membranes can be available inverse in the element so that the total area of the membrane It can be increased. However, the 8a grooves formed in the surface of the knitting or knitting element and serving as step for the filtered liquid can not be large. Thus, the resistance to the flow of filtered liquid is large, and the low separation performance.

If it is determined that the average thickness of the element of knitting or knitting 8b is larger than 0.4 mm, They solve the problems mentioned above. However, the number of the reverse osmosis membranes that can be arranged in the element decrease, and hence the amount of liquid filtered by element decreases. In addition, a difficulty arises when rolling in spiral the knitting or knitting element around the outer surface of the hollow tube since the stiffness of the element of fabric increases.

Determining the average thickness of the element of fabric or knitting 8b so that it is within the range above mentioned, a sufficient size of grooves 8a and a total area larger membrane in the element can be obtained from it weather. Therefore, a sufficient water flow is ensured filtered in the element. The average desirable thickness of the element of fabric or knitting is from 0.15 to 0.3 mm.

The grooves 8a formed on the surface of the knitting element or knitting 8b serve as steps for the filtered liquid and are covered with a permeable fabric element 8c (described below). If the grooves have a width too large, the resistance to the flow of filtered liquid may increase due to the presence of the permeable fabric element that It can be deformed in high pressure operation. Further, if the number of grooves formed is too large, the force of the tissue element or knitting together decreases. By On the other hand, if the number of grooves formed is too small, the Flow rate of filtered liquid decreases.

In this sense, it is desirable that the grooves 8a be 0.1 to 0.2 mm wide and 0.05 to 0.2 mm deep, and that grooves are formed in an index of 18 to 25 by 1 cm in the surface of the knitting or knitting element.

If the grooves are formed to meet the said requirements, the resistance to the flow of filtered liquid is maintained sufficiently low and the permeable fabric element is supported with in order to prevent it from deforming and sinking in the furrows even in high pressure operation.

More desirably, the grooves 8a are 0.1 to 0.15 mm wide and 0.1 to 0.15 mm deep, and the grooves are formed in the knitting element or knitting at an index of 20 to 25 per 1 cm

It is noted that width, depth, and number of grooves mentioned above are obtained by making a average of the width, depth and number of values grooves measured in at least 10 positions on a photograph taken in an amplification of 10 to 50.

The knitting or knitting element 8b is not limited to any special class as long as it meets said structural requirements. Desirably, it is a knitting element because the knitting has a high quality and can be produced at a low price. There are several kinds of knitting such as " double denbigh ", " queens cord ", " three-guide-bar ". Any kind of knitting can be used as long as it can provide steps for the filtered liquid and does not deform even in high pressure operation.

The knitting or knitting element 8b It can be made of any material as long as the material can maintain a shape of a passing element and the components of the material does not dissolve in the filtered liquid. For example, polyamide such as nylon, polyester, can be used polyacrylonitrile, polyolefin such as polyethylene and polypropylene, polyvinyl chloride, polyvinylidene chloride, polyfluoroethylene, carbon material and the like.

Among the said materials, polyester is desirable because the element of knitting or knitting (described later) which is made of polyester shows a resistance enough at pressure even in high pressure operation and It is easy to handle.

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Preferably, the tissue or tissue element knitted is subjected to a cure to increase its stiffness so that the fabric element cannot be deformed in operation at high pressure

Healing can be performed, for example, impregnating the fabric element or knitted fabric already formed with liquid resin such as melanin or epoxy and hardening it. If he knitting element or knitting is made with material thermally fusible, can be subjected to thermal fusion in which the fibers that constitute the fabric element are heated to merge and fix each other.

In addition, the element of knitting or knitting can be subjected to calendering, to press irregularities tiny on the surface of the fabric element due to the irregular external shapes of the component fibers thereof. In In this case, the knitting or knitting element has a very smooth and flat surface, and therefore the fabric element permeable and reverse osmosis membrane that are in contact with the element of knitting or knitting they do not suffer the local or uneven deformation even at high operation pressure, so the durability and performance of the element They are also improved.

The permeable fabric element 8c placed on the grooved surface of the knitting or knitting element 8b no It is limited to any special type. Nonwoven fabric is desirable since which has sufficient liquid permeability and shows good deformation resistance running at high pressure.

Nonwoven fabrics are classified in a fabric non-woven called non-oriented whose component fibers are not oriented, a nonwoven fabric whose component fibers are oriented in a defined direction, and a non-woven fabric of a intermediate oriented nature. For the permeable fabric element 8c of the present invention, any of those three types of non-woven fabric can be used, but the non-woven fabric included of component fibers oriented in a defined direction is desirable since it can provide sufficient stiffness within A certain range of thickness.

When a nonwoven fabric element is used comprised of oriented fibers, it is desirable to put the element of nonwoven fabric on the grooved surface of the fabric element or knitting 8b so that the oriented fibers cross the direction extending from grooves 8a at right angles.

The nonwoven fabric element disposed of this way has anisotropy in strength and rigidity, so that shows greater force in the direction perpendicular to the orientation of the component fibers when receiving tension from deformation such as bending and twisting action. For the so much, even when operating at high pressure, it prevents the nonwoven fabric element deforms and sinks into grooves 8a of the knitting or knitting element.

The average thickness of the permeable fabric element 8c is determined to be 0.05 to 0.2 mm. If the average thickness It is smaller than 0.05mm, the permeable fabric element 8c is deformation in high pressure operation, and flow resistance of filtered liquid increases. If the average thickness is larger than 0.2 mm, stiffness and resistance to deformation is improved. Without However, the number of reverse osmosis membranes that are can be arranged in the element decreases, and the total area of the membrane decreases accordingly. In addition, flow resistance of filtered liquid increases. The desirable average thickness of the element of cloth is from 0.07 to 0.15 mm.

Determining that the average thickness of the element of permeable fabric 8c is within said range, the incidence of deformation can be suppressed even in high operation pressure, and at the same time a sufficient total area can be obtained of the membrane in the element.

It is noted that the average thickness above said is an average obtained by measuring the thickness of an element of fabric in at least 10 positions using a thickness gauge of precision and averaging the measured values.

Although the permeable fabric element 8c is not limited in liquid permeability, it is desirable that, in the case where the feeding environment is pure water, the permeable fabric 8c shows water permeability of 0.5 m 3 / m 2 \ mpd / min or greater in terms of coefficient of permeability at a temperature of 25 ° C. In this case, the resistance to the flow of filtered liquid is small and the loss of Pressure decreases. More desirably, the permeable fabric 8c is a non-woven fabric element that has a permeability coefficient of 0.8 m 3 / m 2 \ cdotMPa \ cdotmin or greater in relation to pure water of 25 ° C.

The permeable liquid cloth element 8c can be made of any material as long as it does not involve deformation substantial even in high pressure operation and its Components do not dissolve in the filtered liquid. For example, Polyamide such as nylon, polyester, can be used polyacrylonitrile, polyolefin such as polyethylene and polypropylene, polyvinyl chloride, polyvinylidene chloride, polyfluoroethylene, carbon material and the like.

Among such materials, it is desirable to Polyester because polyester non-woven fabric is easy to handle and it has great strength, and the polyester components dissolve Little in the filtered liquid.

Later, the module of reverse osmosis membrane of the present invention.

Figure 10 is a cross-sectional view of a example of a module M of the present invention. The M module includes  reverse osmosis spiral membrane elements 10 according to the claim 1 each having a structure shown in the Figure 1. These elements 10 are received in a cylindrical container at pressure 9a in a state in which they are connected in series between they.

It has a sealing plate on the side of upstream 9c having an inlet 9b for the liquid from feed 6 on one end of the pressure vessel 9. On the other end of the pressure vessel 9, is arranged so waterproof a sealing plate 9c of the downstream side, which it has a 9d outlet for the concentrated liquid produced by the reverse osmosis separation.

A frame element 5 configured to allow the liquid to pass through this is connected to a end of element 10 arranged on the current side plus height of module M. As shown in area J_ {1} in the figure 10, with the use of a sealing element 11, a waterproof structure between the circumference of the element of frame 5 and the inner wall of the pressure vessel 9a. A opening of a hollow tube 1 of element 10 is also sealed by a sealing element 12.

As seen in the J_ {2} area of the figure 10, in module M, an element of the upstream side is waterproofly connected to a downstream side element in such a way that the openings of their respective hollow tubes 1,1 are attached to each other and a sealing element is arranged 12 around the joining part of these elements. The structure waterproof is also formed between the circumference of the frame element 5 of the downstream side element and the inner wall of the pressure vessel 9a with a sealing element eleven.

As seen in the J_ {3} area of the figure 10, the element 10 arranged on the downstream side of the M module is waterproofly connected to the downstream side of the sealing plate 9e such that the opening of a tube gap 1 is in communication with the outlet 9f for the liquid filtered, and a sealing element 12 is arranged around the part that communicates between the hollow tube and the outlet that is formed at the axial center of the running side under the sealing plate 9e.

In module M, a pressure loss that is produces between the feed liquid on the incoming side and the protruding side varies according to the number of elements arranged in the module M. As the number of elements arranged in the module increases, a larger pressure loss occurs and the operating efficiency. The desirable number of items received in the module M of the present invention is from 1 to 10. The number plus desirable is from 1 to 8.

Determining that the number of elements arranged in module M are within said range, the loss of pressure produced between the feed liquid on the side incoming and outgoing side can be decreased. Therefore a decrease in operating pressure due to loss of pressure can be decreased, so the loss of energy can be decreased and the filtered liquid can be obtained with High efficiency

Module M is supplied, through the inlet 9b, with the feed liquid 6 pressurized to a default pressure. Feed liquid 6 flows into the element 10 through the frame element 5 configured to allow the liquid to pass through it. As the liquid of power flows to the downstream side, continues the Reverse osmosis separation of the feed liquid. He filtered liquid 6a ends in the hollow tube 1, flows through the downstream side, and flows from exit 9f.

The remaining feed liquid flows to the downstream side as concentrated liquid 6b, and finally it flows through a 9d outlet in its most concentrated state.

In this way, the feed liquid 6 supplied in the M module under pressure is separated in liquid filtrate and concentrated liquid. It should be noted, the liquid separate concentrate has the same pressure energy as the feed liquid 6.

Therefore, in the separation process, it produces little polarization of concentration on surfaces of the reverse osmosis membranes, and the liquid High quality filtering can be obtained at a high rate of Recovery.

In particular, the deformation of the elements passage of filtered liquid does not occur even in operation at high pressure, and therefore, the rate of recovery of impregnated liquid improves even more. The use of the module is favorable, for example, for seawater desalination because the cost of water production decreases.

Now, the apparatus and method of reverse osmosis separation according to the present invention.

Figure 11 is a block diagram showing, by means of an example, the basic structure S_ {0} of the apparatus of reverse osmosis separation of the present invention.

The apparatus S_ {0} comprises a section T_ {1} of separation of feed liquid and pressurization means of feed liquid P_ {1} arranged in the section of upstream side spacing T1. The section of separation of the feed liquid T1 has a gradual configuration comprised of modules M of the present invention shown in figure 10 and connected in parallel or in series between them.

The feed liquid 6 as seawater is supplied to the pressurizing means P1 where it is pressurized at a predetermined pressure. The pressurized feed liquid is supplied to the modules M of the present invention which constitutes the separation section T1 in which the reverse osmosis separation continues, where the
feed liquid is separated into filtered liquid 6a having predetermined the quality and concentrated liquid 6b.

The pressure of the feed liquid 6 is represents by adding an effective pressure and the pressure Osmotic feeding fluid. The pressure varies according to the solute class and concentration of feed liquid. To produce the filtered liquid by osmosis separation Inverse efficiently, it is desirable that the effective pressure to be 0.5 to 7.0 MPa, and more desirable to be from 1.5 to 6.0 MPa.

Taking an example where the liquid from feeding is sea water, the osmotic pressure of the feeding of seawater that has a salt concentration of 3.5% it is generally 2.5 MPa, and it is preferable to determine the pressure of seawater feed within a range of 3.0 to 9.5 MPa. Determining that the seawater feed pressure It is within this range, the separation of reverse osmosis by membranes it can be performed efficiently. A range of most desirable pressure is 4.0 to 8.5 MPa. In liquid pressure power supply that is within this range, can obtain filtered water of more favorable water quality. It's more desirable pressure within a range of 6.0 to 8.5 MPa.

Pressurization means P_ {1} can be any medium as long as they can pressurize the liquid from 6 feed at a pressure necessary for reverse osmosis. By For example, a high pressure electric pump can be used. Is favorable a hydraulic turbocharger that pressurizes the pump (described later), because it can pressurize the liquid from power and supply it to a current side module below M. In addition, this pump can recover the energy part of concentrated liquid pressure produced in module M and add the same to the feed liquid, where the pressure of the liquid from Feeding is increased and used. So, the bomb of Pressurization of this type helps to operate the device S_ {0} with high energy efficiency and a low cost of handling apparatus and production of the filtered liquid.

Now, a favorable example will be explained where the apparatus and the reverse osmosis separation method of the present invention for desalination of seawater.

Figure 12 is a block diagram showing a favorable example S1 of the osmosis separation apparatus Inverse of the present invention for water treatment of sea.

The device S_ {1} together is formed in two stages Basically, the preceding stage comprises a first separation section T_ {0}, which includes a plurality of modules of reverse osmosis membrane M 0 connected in parallel or in series with each other, and a high pressure electric pump P_ {0} arranged upstream from the side of the separation section T_ {0} and serving as a means of pressurization. The next stage comprises a second separation section T 1 comprising a plurality of reverse osmosis membrane modules M of the invention present as shown in figure 10 connected in parallel or in series with each other, and a turbocharger pump of pressurization P_ {T} arranged upstream next to the section of separation P_ {T} and serving as a means of pressurization. The first separation section T_ {0} is connected to the pump pressurization P_ {0}.

The hydraulic pressure turbocharger pump P_ {0} used in the apparatus S_ {1} is of a type described, for example, in the Japanese Preliminary Publication of Patent No. 1-294903. This pump is provided with a cover where a turbine section and a pump section (the compressor section) are directly and coaxially connected to each other. The pump section is operated to pressurize the water supplied, using the pressure energy portion of, for example, the high pressure salt water ( Brine Water ) flowing in the turbine section.

The M_ {0} modules that constitute the stage previous can be or conventional modules actually used for desalination of seawater or M modules of this invention shown in figure 10.

Preferably, the number of modules M_ {0} which constitute the preceding stage is 1 to 3 times, more preferably 1.5 to 2.5 times the number of modules M_ {1} that They constitute the later stage.

Determining the number of modules in each stage to meet these requirements, the amount and pressure of Seawater supplied to the modules at each stage can be convenient, thus improving the quality of filtered water produced in the modules at each stage. At the same time, the effectiveness of reverse osmosis separation improves, whereby filtered water It can be obtained with less energy.

In the device S_ {1}, the seawater intake 13 it is pressurized at a predetermined pressure by the electric pump high pressure P 0, and is subject to osmosis separation inverse by the modules M_ {0} in the first separation section T_ {0}, where seawater is separated into filtered water 6a_ {1} and concentrated water 6b1, having a pressure p.

The concentrated water 6b1 flowing in the pump section R1 of the pressurization pump P_ {0} is pressurized at a pressure p 1 (p 1> p). The liquid 6b_ {1} concentrate is supplied under pressure in the M modules of the present invention constituting the second separation section T_ {1} where the concentrated liquid is subject to separation of reverse osmosis by the M modules, to be separated in water filtered 6a 2 and concentrated water 6b 2, having a pressure p_ {2}.

Since the osmotic pressure of seawater 13 (which has a salt concentration of 3.5%) is 2.5 MPa, the seawater feed has a desirable pressure p of the It is within a range of 3.0 to 9.5 MPa. Determining the pressure p of the seawater feed for that is within this range, the osmosis separation Reverse by membranes can be performed efficiently. A most desirable range is 4.0 to 8.5 MPa. At the determined pressure p that is within this range, filtered water can be obtained from more desirable quality. A more desirable range is 6.0 to 8.5 MPa.

Since the seawater feed is concentrated on the modules in the preceding stage and their concentration  of salt increases, the osmotic pressure of the concentrated water 6b1 supplied to the M modules in the next stage becomes larger. Thus, the pressure p 1 of the concentrated water 6b 1 has a relation p_ {1}> p in relation to the pressure p in the stage preceding. The salt concentration of the concentrated water 6b1 it is approximately 4.0 to 6.0%, and the osmotic water pressure 6b1 concentrate is approximately 3.0 to 5.0 MPa. For obtain high quality filtered water efficiently in the M modules in the later stage, it is desirable to determine the pressure P_ {1} to be within a range of 5.0 to 12.0 MPa. A more desirable range is 7.0 to 11.0 MPa, and an even more range desirable is 8.0 to 10.0 MPa.

The concentrated water 6b2 is supplied to pressure to the turbine section R2 of the pressurization pump  P_ {0}, and part of the pressure energy thereof is added to the 6b_ {1} concentrated water supplied to the pump section R_ {1}. In other words, the pressure energy is partly consumed to pressurize the concentrated water 6b_ {1} under pressure p_ {1}. Then, the concentrated water 6b2 is discharged. The all filtered water is equal to the sum of filtered water a 6a_ {1} and filtered water 6a_ {2}.

In the above, the structure has been described basic and operation of the device S_ {1}. Later on, it describe how the device S1 is actually handled.

In the operation of the device S1, the seawater 13 and undergoes preliminary treatment (described later) to prevent the deterioration of membranes. So he seawater is pressurized at a predetermined pressure by the pump high pressure electric P_ {{}} and is subjected to the separation of Inverse osmosis.

Although it is possible to adopt the sea water intake, the beach ground water intake and the osmotic water intake for seawater intake, permeable ( permeative ) or water intake is desirable. groundwater from the beach ( beach well water ) since high clarity seawater can be taken, so that preliminary treatment can be simplified (described below).

The preliminary treatment, which includes removing the pollution substances contained in the water intake of sea, is implemented by coagulating sand filtration where the seawater is then filtered in a coagulant such as chloride ferric, polychlorinated aluminum, aluminum sulfate or additionally added polychlorinated aluminum Or, a filtration of secondary coagulation (refinement filtration).

For seawater intake, for example, by the impregnated water intake, ultrafiltration is carried out using microfilms or ultrafiltration membranes. These leaks can be performed separately or in comparison.
bination It is desirable that the pollution index (FI) of seawater be lower than about 3 to 4.

Making the pollution index more Under about 3 to 4, it prevents substances from contamination are deposited on the membrane surface in reverse osmosis membrane elements, and therefore it can prevent an increase in pressure loss and pressure of operation, whereby filtered water can be produced stably for a long time.

For preliminary treatment, a coagulating sand filter or a refinement filter, which is comprised of a pressure vessel filled with some kinds of sand arranged in layers and having different grain sizes, the filter is configured to submit the water supply of Sea filtration under a predetermined pressure. The ingredients and the grain sizes of the sand are chosen according to the quality of sea water. As for the ingredients, it is desirable sand that have a low copper content, because if the copper content of the sand is high, copper tends to dissolve in seawater, react with chlorine, sulfate ions and the like, and to deteriorate reverse osmosis membranes.

As ultrafiltration membrane and membrane of microfiltration, a hollow fiber element or a spiral element. Any of the elements can be used in the apparatus of the present invention. As materials for the ultrafiltration membrane and microfiltration membrane, it know polyacrylonitrile, polysulfone, sulfidesulfone polyphenelene, polyethylene, polypropylene, polyamide, acetate cellulose and others like that You can use any of these materials.

To destroy the bacteria or inhibit the bacteria growth in seawater, a sterilization treatment by adding NaOCl, which corresponds to amount to chlorine concentration of about 1 to 5 ppm. Regulating chlorine concentration to be approximately 1 to 5 ppm, seawater bacteria can be sufficiently destroyed or inhibited its growth, and production of trihalomethane, caused by the reaction of chlorine with substances organic contained in seawater, can be kept low by Same time. If the chlorine concentration is within the said range, the deterioration of the membranes of reverse osmosis due to oxidation caused by chlorine residues excessive, so the duration of osmosis membranes Reverse can be longer. The treatment described above prevents the deterioration of reverse osmosis membranes.

To the sea water that has experienced the saying treatment, sodium bisulfite (SBS) is added, for example, to extract residual chlorine by neutralization, and acid is added sulfuric acid to regulate the pH of seawater.

The aforementioned series of processes for the sterilization treatment can be performed continuously or intermittently, depending on how seawater is contaminated with the bacterium. For example, intermittent treatment is performed once a day for about 1 to 5 hours, so the Bacteria can be destroyed or inhibited its growth. He interval and duration of treatment can be changed, depending on the degree of pollution of seawater.

To destroy the bacteria or inhibit the Bacterial growth in osmosis membrane elements conversely, a large amount of sodium bisulfite (SBS) is added or sulfuric acid intermittently to seawater which has sodium bisulfite (SBS) has been added. The amount to add sodium bisulfite (SBS) or sulfuric acid and the duration and range of SBS addition can be determined according to the degree of contamination of sea water. Preferably, sodium bisulfite (SBS) is added or sulfuric acid at an index of 100 to 1000 ppm or added so that the pH of seawater can be 4.0 or lower, and the addition is performed once a day, for 1 to 5 hours. Determining the amount, duration and interval of addition of sodium bisulfite (SBS) or sulfuric acid to meet these requirements, the bacteria on membrane surfaces can be destroyed efficiently or inhibited its growth. In this case, the environmental conditions on membrane surfaces are not constant, but change intermittently, so that you cannot occur a problem of abnormal growth of particular bacteria. Hence, the device can work for a long time with stability. It is more desirable that sodium bisulfite (SBS) or sulfuric acid at an index of 300 to 600 ppm or added so that the pH of seawater may be 2.6 or lower, and that the Addition is made once a day, for 2 to 4 hours.

An example will be explained below, in which the seawater that has a salt concentration of 3.5% is desalted for the operation of the device S_ {1}.

One hundred (100) parts of seawater are taken 13 and undergo the preliminary treatment described above, and they supply the high pressure electric pump P_ {0}. The water of sea, pressurized to 6.0 MPa by the high pressure electric pump P_ {0}, is supplied to the first separation section To.

Using the modules M_ {0} of the first separation section To, a first separation of reverse osmosis, and 40 parts of fresh water 6a_ {1} are obtained (recovery rate: 40%) and occur at the same time 60 parts of concentrated water 6b1 with a salt concentration of 5.8%

Sixty (60) parts of water are supplied 6b_ {1} concentrate thus produced to the turbocharger pump of pressurization P_ {T} and then supplied to the second section of separation T1 where the second separation of reverse osmosis by the M modules of the present invention, by where 20 parts of fresh water 6a_ {2} are obtained (index of recovery: 33%) and 40 parts of water are produced at the same time 6b2 concentrate having a salt concentration of 8.8%. Concentrated water 6b2 is supplied to the turbine section R2 of the pressurization pump P_ {0}, and part of pressure energy thereof to concentrated water 6b_ {1} that enters the pump section R_ {1}. So, concentrated water 6b_ {1} is pressurized from 6.0 MPa to 8.5 MPa.

As a result of the operation of the device S_ {1}, 60 parts of fresh water and 40 parts of water are produced residual sea of 100 parts of seawater. Recovery rate It is therefore 60%.

In the conventional apparatus shown in the figure 6, the recovery rate is 40%. This means that it produce 40 parts of fresh water and 60 parts of concentrated water (residual seawater) that have a salt concentration of 4.8% of 100 parts of seawater.

On condition that the same amount is produced of fresh water, the apparatus S 1 of the present invention makes possible to decrease an amount of seawater intake, an amount of discharge of residual seawater and a salt content of about two thirds, one half or less and about two third parties, respectively, of those required or observed in the case of the conventional apparatus of figure 6. It is that is, the apparatus S 1 of the present invention can produce a large amount of water of the same amount of water intake from sea with a small amount of operational energy, thereby Water production costs can be reduced.

The permeability of osmosis membranes Inverse increases as the ambient temperature increases. By therefore, the rate of recovery of filtered water that the apparatus S_ {1} shows in summer is different in winter, that is the recovery rate in summer is higher than in winter. For make the device S_ {1} produce a constant amount of filtered water regardless of the seasons, it is desirable regulate the opening of the valves, respectively provided in tubes for filtered water arranged on the running side below the separation sections To and T_ {1}, so that a predetermined back pressure is applied to the filtered water in the modules M_ {0} and M, so that the effective pressure in the reverse osmosis separation is regulated to achieve an adjustment of permeability.

As described above, the element of reverse osmosis membrane, the osmosis membrane module inverse M, and the apparatus S_ {0} and S_ {1} of the invention present are convenient for the objectives of obtaining the liquid filtered from the highly concentrated liquid in a high rate of recovery, such as desalination of seawater. They are also applicable to other concentration objectives of foods such as vinegar, beer, alcohol and juice, concentration of industrial waste, and separating the liquid highly concentrated by the separation of reverse osmosis as in the recovery of valuables of industrial waste, for improve efficiency and lower the cost of these treatments.

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Brief description of the drawings

Figure 1 is a perspective sectional view. of a spiral membrane element of reverse osmosis;

Figure 2 is a cross-sectional view taken along line II-II of figure 1;

Figure 3 is a plan view of a feed liquid passage element;

Figure 4 is a cross-sectional view of a conventional filtered liquid passage element to be arranged in a reverse osmosis membrane;

Figure 5 is a cross-sectional view of another conventional filtered liquid passage element;

Figure 6 is a schematic diagram that shows by way of example a conventional apparatus for reverse osmosis separation;

Figure 7 is a drawing that shows how the feed liquid flows along a passage element of feed liquid;

Figure 8 is a drawing that shows how the feed liquid flows along another passage element of feed liquid;

Figure 9 is a cross-sectional view of a element of passage of filtered liquid used in an element of the present invention;

Figure 10 is a cross-sectional view of a reverse osmosis membrane module including the elements of the present invention;

Figure 11 is a diagram showing the basic structure of an osmosis separation apparatus inverse using the modules of the present invention;

Figure 12 is a diagram showing the basic structure of an osmosis separation apparatus inverse of seawater according to the present invention;

Figure 13 is a graph showing the relationship between the flow rate of feed liquid and the pressure loss showing an osmosis membrane module Reverse when handled.

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Best embodiment of the invention

Example 1, Comparative Example one

(1) Feed liquid passage elements

Network elements a, b each were prepared having a network structure shown in figure 3. As for to the network element a, the average thickness was 0.7 mm, the distance (Y) between the convergence points 7c, 7d was 5 mm, and the angle α was 33 °. As network element b, the average thickness was 0.7 mm, the distance (Y) between the points of convergence 7c, 7d was 4 mm, and the angle α was 47 °.

Each of the network elements a, b is arranged on a flat parallel plate cell (width of pitch: 160 mm, pitch length: 300 mm) such that a line which connects the convergence points 7c, 7d extends in parallel to the direction of passage. The water was flowed to a temperature of 25 ° C, and the flow rate on the cell surface and the pressure loss produced between both cell ends The results are shown in the figure 13.

As evidenced in Figure 13, in the case of the network element a, the pressure loss is very small.

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(2) Reverse osmosis membrane elements and modules

Osmosis membrane compounds were prepared bag-shaped inverse that serve as osmosis membranes reverse, each membrane made of a porous support membrane polysulfone having a surface thereof formed with a thin active layer of crosslinked aromatic polyamide and receiving a Polyester tricot filtered liquid passage element. He Filtered liquid passage element was 0.25 mm in thickness medium and formed on one side with grooves 0.15 mm wide and 0.10 mm deep with an index of 23 by 1 cm. Osmosis membranes inverse compounds, among which the element of network a or b serving as a liquid passage element of feed, were wrapped around the outer surface of a hollow tube, so that two kinds of elements of 1 were prepared m of total length and 200 mm of external diameter. Of the two classes of elements, the element that uses the network elements "a" it will be mentioned as the "a" element and the element it uses The network elements "b" will be mentioned as the element b.

Each element "a", "b" had an area effective membrane of 35 m2.

Six (6) series of elements were placed attached to each other in a pressure vessel, to form a module. The module that has the elements "a" will be mentioned like the "a" module, and the module that has the elements "b" will be mentioned as module "b".

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(3) Module Performance

Modules a, b were each incorporated into an apparatus S_ {0} shown in figure 11. It was supplied aqueous NaCl solution having a salt concentration of 0.05%, a pH of 6.5 and a liquid temperature of 25 ° C to each module at a pressure of 0.7 MPa, and the pressure loss was measured, the Water production yield and NaCl concentration of water filtered.

Each module a, b was managed with an index of 50% recovery.

The results are as follows: Loss of pressure was 1510 hPa in module "a" and 2030 hPa in module "b". The water production yield was 156 m 3 / day in module "a" and 148 m 3 / day in module "b". The NaCl concentration of filtered water was 4.6 ppm at module "a" and 4.9 ppm in module "b".

With module "a" having the elements "a" of the present invention, the loss of pressure produced During operation may decrease, production yield of water can be improved, and filtered water can be obtained from higher quality

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Examples 2 to 5, examples comparatives 2 a 5

(1) Preparation of reverse osmosis membranes and feed liquid passage elements

A polyamide membrane compound was prepared crosslinked aromatic, which was the flat membrane that has the performance such that filtered water was easy to achieve with an index of 0.85 m 3 / m 2 per day and with an expulsion of 99.75% salt when a saline solution having a 3.5% concentration was subjected to osmosis separation inverse, at a pressure of 5.5 MPa. Reverse Osmosis Separation was implemented using a flat evaluation cell of the membrane provided with the composite membrane having an area effective of the 32 cm2 membrane. Composite membrane said above will be mentioned as the membrane I.

Another membrane compound was prepared with crosslinked aromatic polyamide, which was a flat membrane that it has the performance such that the filtered water was easy to achieve with an index of 0.87 m 3 / m 2 per day and with a 99.72% salt expulsion when a saline solution having a 5.8% concentration was subjected to filtration, at a pressure 8.8 MPa, using a flat membrane evaluation cell having an effective area of the membrane of 32 cm2. This membrane will be mentioned as membrane II.

As liquid passage elements of feeding, polyethylene net elements were prepared having a network structure as shown in Fig. 3, where the values of X, Y, angle α and the average thickness are shown in the Table 1.

TABLE 1

one

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(2) Assembly of elements and modules, evaluation of performance

A liquid passage element was prepared filtering comprised of a polyester knitting element and a Element of non-woven polyester fabric. The knitting element of polyester was 0.20 mm medium thick and formed on one side of the same with grooves 0.15 mm wide and 0.10 mm deep with a 23 by 1 cm index. The element of non-woven polyester fabric, placed on the ribbed side of the knitting element, it was 0.10 mm of average thickness, and the coefficient of permeability thereof in ratio with pure water at a temperature of 25 ° C was 0.90 m 3 / m 2 • MPa per min.

Osmosis membrane elements were mounted inverse specified in table 2 combining the step elements of filtered liquid, the liquid passage elements of feed shown in table 1 and the membranes above said I, II in the manner shown in table 2.

2. The modules were assembled by providing a corresponding element in a pressure vessel of each module. The devices S_ {0} as shown in Figure 11 and each accommodating a corresponding module were handled in the operating conditions shown in table 2 for 15 hours, and the filtered water flow and the rate of salt expulsion The results are shown in one as a whole in table 2.

As for example 4 and the comparative example 5, the pressure loss was also measured. The results are shown in table 2.

2

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As evidenced by table 2, when use the elements of the present invention, the flow of water filtered increases, the expulsion of salt increases and the loss of Pressure decreases a lot.

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Examples 6 to 17, examples comparative 6 to 14

A polyamide membrane compound was prepared crosslinked aromatic, which was a flat membrane having such performance that filtered water was easy to achieve with a 0.85 m3 / m2 index per day and with a salt expulsion 99.80% when a saline solution having a concentration of 6.0% underwent separation by reverse osmosis, at a pressure of 9.0 MPa, using a flat evaluation cell of the membrane having an effective membrane area of 32 cm2.

Elements of short woven polyester fiber fabric were prepared, each having a medium thickness and a coefficient of permeability in relation to pure water (at 25 ° C) as shown in Table 3. In addition, the knitting elements were prepared. Unique having a double structure of polyester fiber denbigh , these knitting elements having undergone healing by thermal melting and surface calendering. The knitting elements each had an average thickness as shown in table 3 and were formed on one side with grooves specified in table 3. By placing each nonwoven fabric element on the ribbed surface of a corresponding knitting element, they prepared several kinds of filtered liquid passage elements having a cross-sectional structure shown in Figure 9.

Polyethylene net elements were prepared which serve as passage elements of feed liquid, the network elements having values of X, Y, the angle? and the average thickness as shown in table 3.

Combining those elements in a way shown in table 3 and rolling each combined element around the outer surface of a 32mm hollow tube of diameter, 200 mm external diameter elements were prepared and 1000 mm in length Each element had an effective area of membrane as shown in table 3. In addition, the modules arranging each corresponding element in a container to pressure of each module.

The S_ {0} Appliances as shown in the figure 11 and each incorporating a corresponding module were handled using saline solution at 6.0% concentration, 25º C of liquid temperature and with a pH of 6.5, on the conditions of operation in which the pressure was 9.0 MPa and the flow rate of concentrated liquid was 80 L / min. After running 24 hours, filtered water flow, salt expulsion and Pressure loss for performance evaluation.

If the salt expulsion was 99.7% or greater, the filtered water flow would be 16.0 m 3 / day or greater, and the pressure loss of 11.0 kPa or less, the evaluation of performance \ circle. If the salt expulsion was 99.5 to 99.7%, the filtered water flow was 14.0 to 16.0 m 3 / day, and the pressure loss was 11.0 to 14.0 kPa, the evaluation was given performance \ medcirc. If the salt expulsion was 99.0 to 99.5%, the flow of filtered water was 12.0 to 14.0 m 3 / day, and the pressure loss was 14.0 to 17.0 kPa, the evaluation was given of performance \ Delta.

In other cases, the evaluation of performance 3.

The results are shown in table 3.

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(Table goes to page next)

TABLE 3-1

3

TABLE 3-2

4

TABLE 3-3

5

TABLE 3-4

6

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As evidenced in Table 3, the element of the present invention and the module using it, makes possible produce high quality filtered water with a small loss of pressure at a high flow of permeated water even at high pressure Operating 9.0 MPa.

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Examples 18 to 22, examples comparative 15 to 17

The elements specified in the Table 4 in the same way as the elements of examples 6 to 17. Then the modules were mounted using the elements.

S_ {0} devices were handled as shown in figure 11 and each accommodating a module corresponding, using seawater taken on the coast of Ehime and previously concentrated to a degree that had a total content of dissolved solution of 6.0% by weight and an IF of 3.0 to 4.0, about the operating conditions of the pressure being 9.0 MPa, pH 6.5 and the concentrated water flow rate of 80 L / min After 2000 hours of operation, the salt expulsion, filtered water flow, and loss of Pressure. The index of retention in salt expulsion, the index of retention in filtered water flow, and the rate of change of the pressure loss was calculated from measured values according to the following expressions:

Index of salt expulsion retention (%) = 100 x salt expulsion after 2000 hours of operation / salt expulsion initial

Index of retention in filtered water flow (%) = 100 x water flow filtered after 2000 hours of operation / flow initial water filtered

Index of pressure loss change (%) = 100 x pressure loss after 2000 hours of operation / pressure loss initial

The results are shown as a whole in the table 4.

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TABLE 4-1

7

TABLE 4-2

8

As evidenced in Table 4, changes in the loss of pressure, the flow of filtered water and the Salt ejection are small in the module using the element of the present invention, even if the module works for a long time time using seawater having a high concentration of salt and containing pollution substances corresponding to an IF of approximately 3.0 to 4.0. Therefore, module M can operate with stability for a long time in conditions where The pressure is high and the concentration is high.

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Examples 23, 24, examples comparatives 18, 19

The elements specified in the table 5 in the same way as the elements of examples 6 to 17. The modules were mounted each placing six elements associated with them in a pressure vessel of each module, with these elements connected in series with each other. Each module was incorporated into a second stage of an apparatus S_ {0} shown in Figure 12 and having a first stage that accommodated a module of Conventional reverse osmosis membrane.

Seawater was taken from the coast of Ehime, and ferric chloride was added, serving as a coagulant, continuously with an index of 5 ppm. For the fungicidal treatment for seawater, sodium bisulfite (SBS) was added intermittently at a rate of 3 ppm once a day, for two hours. Then the seawater was subjected to filtration using a coagulating sand filter and a polish filter to have an FI of 3 to 4.

To the sea water that has experienced said preliminary treatment, sodium bisulfite (SBS) was added so flashing once a day, for two hours to remove the chlorine. In addition, for the fungicidal treatment for the elements of reverse osmosis membrane, sulfuric acid was added to the water of intermittent sea once a day, for two hours, of so that the pH of seawater could be 2.5. Using the seawater thus prepared, the apparatus was put into operation, in the one that the operating pressure in the first stage was regulated to be 6.5 MPa so that the recovery rate in the first stage it could be 40%, and the pressure of operation in the second stage was regulated so that the Recovery rate in the second stage could be 33%. After 100 hours of operation performed with the condition If the pH was 6.5, the water quality of the water was measured filtered, operating pressure, and pressure loss.

The results are shown as a whole in the table 5.

As evidenced by table 5, when a desalination apparatus of the multi stage type of seawater works with a high recovery rate of approximately 60%, the use of a module that has a subsequent stage incorporating The elements of the present invention make it possible to produce water from high quality in conditions where the pressure is high and the concentration is high, without requiring an operating pressure too high and without causing too much pressure loss big.

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TABLE 5

9

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Industrial applicability

The osmosis spiral membrane element reverse of the present invention and the osmosis membrane module inverse including the same make it possible to suppress the incidence of the polarization of the concentration on the surface of the membrane of a reverse osmosis membrane and improve resistance at the pressure of a filtered liquid passage element, so that high quality filtered water can be produced so constant with a high recovery rate even when the element is handled at high pressure for a long time with sea water having a high concentration. In the device for reverse osmosis separation where the module is incorporated, the provision of a pressurization turbocharger pump, serving as a pressurization medium for the feed liquid, it makes possible to pressurize the feed liquid with the use of concentrated liquid flow pressure energy. Therefore the Energy cost required to operate the device can be lowered. This contributes greatly to the lowering of the production cost of Water.

Claims (14)

1. Reverse osmosis spiral membrane element (10), characterized in that: a plurality of reverse osmosis membranes bag-shaped (2), filtered liquid passage elements (3) arranged inside said reverse osmosis membranes (2), and a plurality of liquid passage elements of feed (4) interspersed between said osmosis membranes inverse (2) are wrapped around an outer surface of a hollow tube (1) so that only the interiors of said reverse osmosis membranes (2) communicate with through holes (1a) formed on the surface of said hollow tube (1); each of said step elements of feed liquid (4) is a mesh element that has a series of quadrilateral meshes formed by a plurality of linear elements that intersect; two opposite points of convergence (7c, 7d) over four points of convergence (7c, 7d, 7e, 7f) of each of said quadrilateral meshes are adjusted parallel to an axial direction of said hollow tube (1); Y the ratios 2 mm? X? 5 mm and X? Y? 1.8X are satisfied where X designates a distance between said convergence points (7e, 7f) in a direction perpendicular to the axial direction of said tube hollow (1) and Y designates a distance between said convergence points (7c, 7d) in the axial direction of said hollow tube, characterized in that said filtered liquid passage element (3) comprises a knitted fabric or knitting element (8b) of 0.15 to 0.4 mm of average thickness having a plurality of grooves (8a) on at least one of its sides and a liquid permeable fabric element (8c) of 0.05 to 0, 2 mm medium thickness placed on the grooved surface of said knitting or knitting element (8b).

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2. Reverse osmosis spiral membrane element (10) according to claim 1, characterized in that the average thickness of said feed liquid passage element (4) is 0.5 to 1 mm. 3. Reverse osmosis spiral membrane element (10) according to claim 1 or 2, characterized in that a variable range of thicknesses of said feed liquid passage element (4) is comprised between values representing 0.9 times and 1.1 times said average thickness, respectively. 4. Reverse osmosis spiral membrane element (10) according to any one of claims 1 to 3, characterized in that said feed liquid passage element (4) is made from polyethylene or from polypropylene. 5. Reverse osmosis spiral membrane element (10) according to any one of claims 1 to 4, characterized in that the absolute value of an angle between a line linking the convergence points (7c, 7d) that are adjusted in the axial direction of said hollow tube (1) and a mesh leg (7a, 7b) is within a range of 29 to 45 °. 6. Reverse osmosis membrane module (M), characterized in that at least one reverse osmosis spiral membrane element (10) according to any one of claims 1 to 5 is arranged in a pressure vessel (9a) having a inlet for the feed liquid at the level of one end and an outlet for the resulting concentrated liquid at the level of the other end. 7. Reverse osmosis membrane module (M) according to claim 6 wherein two spiral membrane elements reverse osmosis (10) or more are linked in series and arranged in the pressure vessel (9a). 8. Apparatus for the separation of reverse osmosis (S_ {0}), which comprises: a liquid separation section of feed (T1) comprising osmosis membrane modules inverse (M) according to claim 6 or 7, which are linked in Multi-phase form and pressure means of feed liquid (P_ {1}) arranged on the upstream side of said section of separation (T1).

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9. Apparatus for the separation of reverse osmosis (S0) according to claim 8, characterized in that said separation section (T1) comprises reverse osmosis membrane modules (M) according to claim 6 or 7. 10. Apparatus for separating reverse osmosis (S0) according to claim 8 or 9, characterized in that said pressure means (P1) is a turbocharged pressure pump (PT). 11. Apparatus for separating reverse osmosis (S0) according to any one of claims 8 to 10, characterized in that a counter-pressure control valve is provided in one step for the filtered liquid extending from the separation section (T1).

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12. Apparatus for separating reverse osmosis (S1) according to any one of claims 8 to 11, characterized in that said feed liquid is seawater, said reverse osmosis membrane modules (M) are linked by at least in the form of two stages, a high-pressure electric pump (P 0) is arranged on the one side upstream a reverse osmosis membrane (M 0) in the preceding stage, a turbocharger pressurization pump ( P_ {T}) is disposed between the reverse osmosis membrane module (M_ {0}) in the preceding stage and a reverse osmosis membrane module (M) in a subsequent stage, and a passage system is provided to supply the fluid concentrated from the reverse osmosis membrane module (M_ {0}) in the step preceding a compressor section of said pressurization pump (P_ {T}) and to circulate the concentrated liquid from the module of reverse osmosis membrane (M) e n the subsequent step to a turbine section of said pressurization pump (P_ {T}). 13. Osmosis separation procedure reverse, which includes: a stage that consists of feeding liquid from supply (6) to pressurized media (P1) of an apparatus for reverse osmosis separation (S 0) according to any one of the claims 8 to 12 and pressurize the feed liquid (6), and a stage that consists of feeding the liquid pressure feed (6) to a separation section (T1) of the device (S_ {) and separate the pressure feed liquid (6) in filtered liquid (6a) and concentrated liquid (6b).

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14. Osmosis separation procedure inverse of seawater using an apparatus for the separation of reverse osmosis (S_ {1}) according to any one of the claims 8 to 12 comprising: a first stage of separation consisting of feed the seawater under pressure obtained by operating the pump of high electrical pressure (P0) towards a membrane module of reverse osmosis (M_ {0}) in a preceding stage and separate the water of sea under pressure in filtered water (6a1) and concentrated water (6b1); a second stage of separation consisting of feed the concentrated water (6b1) produced in said first separation stage to a reverse osmosis membrane module (M) in a subsequent stage via the compressor section of the pump turbocharger pressurization (P_ {T}) and separate said water concentrated (6b1) in filtered water (6a2) and in water concentrated (6b2); Y a stage that consists in circulating the water concentrate (6b2) produced in said second stage of separation towards the turbine section of said pump of pressurization (P_ {T}).