JPH0571290B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluid separation cell, a spacer assembly for separating diaphragms of a fluid separation cell, and a spacer sheet used in the spacer assembly.

Fluid separation cells used in reverse osmosis, ultrafiltration, dialysis, especially electrodialysis, etc., consist of a stack of shallow chambers, the opposing sides of each chamber being formed by a diaphragm separating it from the next chamber, and Around its sides are constructed spacer assemblies. While different fluids are flowing in adjacent chambers, impurities are transferred from the fluid in one chamber (dilute liquid) to the fluid in the adjacent chamber (concentrated liquid) through the separation membrane. For example, the dilute solution to be washed through one chamber may be salt-contaminated water, and the concentrated solution in the adjacent chamber, which receives impurities from this dilute solution through a diaphragm, may be salt water, seawater, or other water. There are cases.

It is necessary to provide passages for supplying and collecting the dilute solution to one set of chambers and passages for supplying and collecting the concentrated solution to the other set of chambers, passing through the spacer assembly and the diaphragm. will include appropriate cooperating supply and recovery ducts. Each spacer has an opening in the center, which defines the range of the fluid chamber and the fluid supply and recovery duct.

Appropriate transition means should be provided to ensure fluid movement from the appropriate supply or withdrawal ducts to the chamber. Such transition means take the form of slots, holes or other passageways extending between the duct and the chamber opening.

This type of fluid separation cell significantly reduces the purity that can be obtained in the event of a leak from a fluid containing impurities (concentrate) to a fluid that has been cleaned or is being cleaned (dilute). There is a serious problem with the decline. Therefore, leakage between adjacent chambers and between supply or collection ducts and chambers, except through the desired transition means, is minimized;
Otherwise, it is important to eliminate them. Therefore, it is necessary to stack the spacer and diaphragm in a way that prevents leakage. Unfortunately, this is not yet easily achievable at this time, severely limiting the value of methods such as electrodialysis. One fundamental obstacle is that when slots or other transition means extend into the surface of the spacer between the supply or return duct and the opening, the adjacent membranes and adjacent spacer assemblies may The problem is that it gets stuck in the slot, resulting in leakage.

A particular problem is in the case of dialysis, especially electrodialysis. This is because in dialysis, it is necessary to maintain a constant high flow rate and an equal flow rate in each chamber. Unequal flow rates result in an excessively high concentration of impurity ions in regions of the concentrator cell with low flow rates, thereby resulting in precipitation of impurity salts in the shallow chambers. Once significant precipitation occurs, the cell is often rendered inoperable.

Simple types of spacer assemblies have also been tested in electrodialysis cells. This is a uniform plastic mesh that extends through the cell and separates the diaphragm over its entire area, optionally with rigid flat rods around each edge of the mesh to provide flexibility. The diaphragm forms a seal with this rod. However, this is not very effective, the spacer assembly is difficult and expensive, and leakage remains a problem.

U.S. Pat. No. 3,256,174 uses one spacer for each chamber and either drills a hole in the spacer frame from the feed passageway to the opening or forms a groove in one layer of the spacer. This is covered with an overlay laminate. however,
This method is expensive and requires thick spacers, resulting in low indoor separation efficiency. Furthermore, since the fluid is not supplied and collected evenly across the width of each chamber, there is a risk of precipitation occurring in the concentration chamber.

British Patent No. 921094 and French Patent No. 1281549 also provide a unitary spacer with transition means extending between the opening and the supply or withdrawal passage, the transition means being connected to at least one bend. This reduces the possibility that the diaphragm will invaginate into the slot.
Another solution disclosed is to include a porous pressurized spacer within the slot to support the membrane and allow water to pass through the slot. However, such spacers are difficult to manufacture and result in extremely high pressure drops between the supply duct and the chamber between the membranes. Here again, it is possible that the fluid supply is not uniform and that there are quiescent zones where precipitation can occur.

British Patent No. 1447174 and West German Patent No.
In 2418369, various combinations of spacers and diaphragms are proposed, again in which the transition means are constituted by passages extending between the supply or withdrawal duct and the opening.

If only one such spacer is used between a pair of diaphragms, the diaphragm will cave into the slot and leakage will occur between the supply duct and the adjacent chamber. The patent specification discloses the use of a frame with molded members on both sides of the spacer. The frame is rigid enough not to cave into the slot, yet provides a continuous flat bar that contacts the diaphragm between the fluid supply duct and the opening. In the method disclosed herein, at least two
Since different types of spacers are required, and at least three spacers are required for each pair of membranes, there is a disadvantage that the separation chamber becomes too deep.

In US Pat. No. 3,703,466 and French Patent No. 2,070,975 several pairs of spacers are used between a pair of diaphragms. The transition means are provided by slots, but each slot extends only halfway between one of the ducts and the opening, and the slots cooperate in the area between the duct and the opening. This forms a continuous fluid passage. Although this approach may solve some of the leakage problems by allowing the diaphragms on both sides of the spacer pair to contact a continuous hard surface around them, it is shown in U.S. Pat. This structure poses serious problems, especially when used in high flow rate dialysis applications. Since the duct is generally composed of relatively small holes placed in the corners of the spacer, the slots extending part way between the passages and openings in these corners are necessarily very few in number and small in size. becomes smaller. If such cells are operated at high flow rates, the pressure drop will therefore be very high and there is a high risk of stagnation in the concentrate chamber. Another problem with the design of US Pat. No. 3,703,466 is that two types of spacer sheets must be provided in each chamber.

French Patent No. 1603631 also discloses various combinations of spacer sheets,
Again, the pressure drop is even worse in this arrangement because the ducting is confined to the corners and the circulation duct passes through a very narrow orifice before reaching an elongated passage that cooperates with a narrow slot in the adjacent spacer. There is a tendency to do so. Therefore, this would also have a serious problem of pressure drop and would cause a serious problem of settling due to the quiescent zone.

GB 1013464 uses a pair of cooperating spacers to define each chamber. One spacer sheet is provided with a slot that extends from the duct toward the opening, but only reaches halfway there, and the other spacer sheet has a slot that extends from the opening toward the duct, but reaches only halfway there. There is. The slots in one seat overlap the slots in the other seat, creating a continuous channel from the duct to the chamber. The slots disclosed in this patent are very wide, with only about six slots on each side of the seat. For this reason, there is still a high risk of static zones occurring, and especially since the width of the slot is too large, there is a high possibility that the seat will fall into the slot and cause leakage, even if the seat is made of a fairly rigid material. . It is likely for this reason that assemblies of the type disclosed in this patent have not been commercialized. A similar problem exists with the spacer assembly disclosed in GB 1439876.

The first object of the present invention is to provide a spacer assembly which can reduce the possibility of fluid passages being closed due to misalignment between slots when spacer sheets are assembled, and which can easily perform effective alignment between slots. Our goal is to provide the following.

According to the first invention, the above-mentioned object is a spacer assembly for separating the membranes of a fluid separation cell, which includes a pair of spacer sheets, each of which has a spacer assembly for containing a fluid. An opening provided in the center of the seat;
a fluid supply duct provided along one of the two opposing sides of the spacer sheet and extending over substantially the entire width of the opening for supplying said fluid to the interior of the opening; and, in order to discharge the fluid supplied to the opening to the outside of the opening,
a fluid discharge duct provided along the other of said two opposing sides and extending over substantially the entire width of the opening; and a fluid supply duct opening into either of the openings. and are substantially uniformly spaced across the width of said one of said fluid supply ducts of said opposite sides;
a plurality of first slots each extending part way between the fluid supply duct and the opening; and a plurality of first slots opening into either the fluid discharge duct or the opening, the other fluid discharge of the aforementioned opposing sides. a plurality of second slots substantially uniformly spaced across the width of the duct and each extending part way between the fluid evacuation duct and the opening;
The opening in one of the pair of spacer sheets and the first slot opening into one of the fluid supply ducts are connected to the opening in the other pair of spacer sheets and the first slot opening into the other of the fluid supply duct. respectively forming a first fluid passageway between the opening and the fluid supply duct, the opening in said one of said pair of spacer sheets and a first fluid passage opening into said one of said fluid discharge duct; The second slot cooperates with an opening in the other of the pair of spacer sheets and a second slot opening into the other of the fluid discharge ducts to allow a second fluid to flow between the opening and the fluid discharge duct. Some of the pairs of first slots each forming a passageway and forming said first fluid passageway include an enlarged portion projecting to at least one side with respect to at least one of said first pair of slots; some of the second pairs of slots each having a closed end of said at least one of said first pair of slots and forming said second fluid passageway; spacers separating the membranes of the fluid separation cells, each having an enlarged portion projecting on at least one side with respect to at least one of the pair of said second slots; This is accomplished by assembly.

Each of the pair of spacer sheets constituting the spacer assembly of the first invention includes a first slot arranged at substantially uniform intervals across the width of the fluid supply duct, and a second slot also arranged at substantially uniform intervals across the width of the fluid supply duct. The spacer assembly of the first invention is arranged at substantially uniform intervals across the width of the fluid discharge duct, and the spacer assembly of the first invention includes the first slots provided in each of the pair of spacer sheets. cooperate with each other to form a first fluid passage between the opening and the fluid supply duct for supplying fluid from the fluid supply duct to the opening; The aforementioned second slots are configured to cooperate with each other to form a second fluid passage between the opening and the fluid discharge duct for discharging the fluid in the opening to the fluid discharge duct. further, some of the first pairs of slots forming the first fluid passageway are provided with an enlarged portion at the closed end of at least one of the first pairs of slots;
Similarly, some of the pairs of second slots forming the second fluid passages are provided with an enlarged portion at the closed end of at least one of the pairs of second slots, thereby preventing the first invention from forming. In this spacer assembly, there is a misalignment between the first slot of one spacer sheet and the first slot of the other spacer sheet; The possibility of closure of the first and second fluid passages due to misalignment between the two slots is greatly reduced, and effective alignment between the first slot and effective position between the second slot is greatly reduced. Can be easily matched. That is, the spacer assembly of the first invention can reduce the possibility that the fluid passage will be closed due to misalignment between the slots when the spacer sheets are assembled, and can easily perform effective alignment between the slots. obtain.

The second object of the present invention is to provide a fluid separation system that can reduce the possibility of fluid passages being closed due to misalignment between slots when spacer sheets are assembled, and that can facilitate effective alignment between slots. The aim is to provide cells for use.

According to the second invention, the above-mentioned object is a fluid separation cell formed by alternately stacking diaphragms and spacer assemblies, each of which includes a pair of spacer sheets. and each of the spacer sheets has an opening provided in the center of said spacer sheet for accommodating a fluid, and two opposite sides of said spacer sheet for supplying said fluid inside said opening. a fluid supply duct provided along one of the sides and extending over substantially the entire width of the opening; a fluid discharge duct provided along the other of the two opposing sides of the opening and extending over substantially the entire width of the opening; and a fluid supply duct opening into either of the openings. and are substantially uniformly spaced across the width of said one of said fluid supply ducts of said opposite sides and each extending partway between said fluid supply duct and said opening. a plurality of first slots opening into one of the fluid evacuation ducts and the openings and being substantially uniformly spaced across the width of the other fluid evacuation duct on said opposing sides; and a plurality of second slots each extending halfway between the fluid discharge duct and the opening, the opening in one of the pair of spacer sheets and the opening in one of the fluid supply ducts. a first slot that cooperates with an opening in the other of the pair of spacer sheets and a first slot opening into the other of the fluid supply ducts to allow a first fluid to flow between the openings and the fluid supply duct; A second slot respectively forming a passageway and opening into the opening in the said one of the said pair of spacer sheets and into the one of the fluid discharge ducts is connected to the opening in the said other of the said pair of spacer sheets. a first fluid passage forming the first fluid passage, each cooperating with a second slot opening in the other side of the fluid ejection duct to form a second fluid passage between the opening and the fluid ejection duct; Some of the pairs of slots each have an enlarged portion projecting to at least one side with respect to at least one of the first pair of slots, at the closed end of the at least one of the first pair of slots. and some of the pairs of second slots forming said second fluid passages have enlarged portions projecting on at least one side with respect to at least one of said second pairs of slots. This is accomplished by fluid separation cells formed by alternating stacks of diaphragms and spacer assemblies, each having a closed end of said at least one of the second pair of slots.

In each of the pair of spacer sheets constituting the spacer assembly included in the fluid separation cell of the second invention, first slots are arranged at substantially uniform intervals across the width of the fluid supply duct, The second slots are also substantially uniformly spaced across the width of the fluid discharge duct;
In the spacer assembly included in the fluid separation cell of the second invention, the first slots provided in each of the pair of spacer sheets cooperate with each other to connect the opening and the fluid supply duct. Between,
A first supplying fluid from the fluid supply duct to the opening.
The second slots provided in each of the pair of spacer sheets cooperate with each other to direct the fluid in the opening between the opening and the fluid discharge duct. configured to form a second fluid passageway discharging into the discharge duct, and further configured to form some of the first pairs of slots forming the first fluid passageway. an enlarged portion is provided at one closed end;
Similarly, some of the pairs of second slots forming the second fluid passageway are provided with an enlarged portion at the closed end of at least one of the pairs of second slots, so that the present second invention In this fluid separation cell, there is a misalignment between the first slot of one spacer sheet and the first slot of the other spacer sheet, and the misalignment between the second slot of one spacer sheet and the other spacer sheet. The possibility of closure of the first and second fluid passages due to misalignment between the first slot and the second slot is greatly reduced, and effective alignment between the first slot and effective alignment between the second slot is greatly reduced. positioning can be easily performed. That is, this second book
The fluid separation cell of the invention can reduce the possibility of fluid passageway closure due to misalignment between slots when spacer sheets are assembled and can facilitate effective alignment between slots.

The third object of the present invention is to reduce the possibility that a fluid passage will be closed due to misalignment between slots when spacer sheets are assembled to assemble a spacer assembly, and to facilitate effective alignment between slots. The object of the present invention is to provide a spacer sheet that can be used for various purposes.

According to the third aspect of the present invention, the above-mentioned object is a spacer sheet used in a spacer assembly for separating diaphragms in a fluid separation cell, the spacer sheet having an opening provided in a central part of the spacer sheet to accommodate a fluid. a spacer sheet along one of the two opposite sides of the spacer sheet and extending over substantially the entire width of the opening for supplying said fluid to the interior of the opening; a fluid supply duct;
provided along the other of the two opposing sides and extending over substantially the entire width of the opening for discharging the fluid supplied to the opening to the outside of the opening; a fluid discharge duct, a fluid supply duct and an opening, the fluid supply duct being substantially uniformly spaced across the width of said one of said fluid supply ducts on said opposite sides; and a plurality of first slots each extending halfway between the fluid supply duct and the opening, and opening into either the fluid discharge duct or the opening,
a plurality of second ducts disposed at substantially uniform intervals across the width of the other fluid evacuation duct on said opposing sides and each extending part way between the fluid evacuation duct and the opening; slots, and some of the first slots have enlarged portions projecting on at least one side with respect to each of the several first slots. at each closed end, some of the second slots having an enlarged portion projecting on at least one side with respect to each of the several second slots. This is accomplished by a spacer sheet used in a spacer assembly that separates the membranes within the fluid separation cell, having at each closed end of the slot.

In the spacer sheet of the third aspect of the invention, the plurality of first slots that are open to either the fluid supply duct or the opening are substantially uniform over the width of one of the fluid supply ducts on the opposing sides. A plurality of second slots are arranged at various intervals and each extend part way between the fluid supply duct and the opening, and a plurality of second slots open to either the fluid discharge duct or the opening. the other side of the fluid discharge duct and each extending part way between the fluid discharge duct and the opening; some of the slots have an enlarged portion at the closed end of each of said plurality of first slots, projecting on at least one side with respect to each of said plurality of first slots; Further, some of the second slots may include an enlarged portion projecting on at least one side with respect to each of the several second slots.
at each closed end of the slot.

Thus, on said one of the opposite sides, a second slot (slot provided on the said other side of the opposite sides) is provided which cooperates with the first slot opening into the fluid supply duct. opens into the opening, and on the aforementioned one of the opposing sides,
A second slot (a slot provided on the aforementioned other side of the opposite side) which is to cooperate with the first slot opening into the opening opens into the first slot so as to open into the fluid outlet. and a second slot, and the second spacer sheet is rotated 180 degrees with respect to the first spacer sheet within the same plane, and the second spacer sheet is inserted into the first spacer sheet. If they are arranged in an overlapping manner, the first
The fluid formed by the cooperation of the first slot and the second slot due to the misalignment between the first slot of the spacer sheet and the cooperating second slot of the second spacer sheet. The possibility of passageway blockage is greatly reduced, and the first and second slots
Effective alignment between the slots can be easily achieved. That is, the spacer sheet of the third invention can reduce the possibility that the fluid passage will be closed due to misalignment between the slots when the spacer sheets are combined to assemble the spacer assembly, and can also ensure effective alignment between the slots. can be easily performed.

In the first, second and third inventions, each pair of cooperating slots forms a fluid passageway extending between the opening and the duct, and at least one of the pairs of slots is formed into a slot having an enlarged portion. It is important to. Although it is possible to have all of the slots in one sheet and none of the slots in the other sheet, it is generally preferred to have at least some of the slots in each sheet be expanded. desirable. Individual spacer sheets with enlarged portions in at least some of the slots as described above form the first, second and third inventions. Generally at least 10%, preferably at least 30%, and most commonly at least 50% of the slots in such seats will be slotted with enlargements.

By arranging the slots along the ducts of both sheets, substantially all of the slots without enlargements cooperate with the slots with enlargements. For example, the slots of both sheets may be arranged in groups according to their type, or the slots with and without enlarged portions may be arranged alternately along the duct. Preferably, most or all of the slots are enlarged slots.

In the first, second, and third aspects of the present invention, some of the slots arranged along one duct are opened to the opening, and other slots are opened to the duct. In this case, the slots may be arranged as a group for each type, for example. However, each duct is preferably selected from a type 1 duct and a type 2 duct. All the slots along the Type 1 duct open into the duct, and all the slots along the Type 2 duct open into the opening. In spacer assemblies containing such preferred sheets, type 1 ducts of one sheet cooperate with type 2 ducts of the other sheet. It is advantageous to have one type 1 duct and one type 2 duct per spacer sheet, since two substantially identical sheets can be used to form a spacer assembly.

In the system described in GB 1013464, the width of the open end of the slot and the width of the closed slot extension are equal, resulting in a rectangular slot. The smaller the width of the slot, the smaller the risk of the other sheet invading into the slot and causing leakage. Unfortunately, even with guide holes drilled in the spacer sheet to support bolts and other fasteners, it is still difficult to accurately position the spacer sheet through the fluid separation cell, and the width of the slot can be difficult to achieve. The smaller the size, the more difficult it becomes. Therefore, British patent no.
Merely reducing the width of the slot as disclosed in No. 1013464 does not immediately lead to a useful product. In practice, it is common to misalign the slots so that they do not cooperate effectively and do not provide the necessary continuous path for fluid flow between the fluid passageway and the fluid chamber. Due to misalignment, the slot may become blocked and no flow may occur, or
Alternatively, the slot size may be reduced, resulting in increased pressure drop.

The first, second and third inventions can be used for ultrafiltration performed at relatively low pressures, such as 10 bar or less, and are particularly effective in dialysis and electrodialysis equipment. It is also the first to overcome the problems of the prior art.

By providing a duct that spans substantially the entire width of the opening and by providing slots substantially evenly along the duct, uniform flow can be obtained through each chamber formed by the two openings. The risk of harmful precipitation forming inside the room is therefore also minimized. The provision of an enlarged portion in one or both slots of each cooperating slot pair facilitates effective alignment of the slots even when the open ends of the slots are very narrow. Also, since the slots are substantially evenly spaced across the width of the chamber, pressure drop is not a significant problem even if the open ends of the slots are narrow. The open ends are sufficiently narrow that there is little risk of adjacent spacer sheets invaginating the open ends of the slots, and each septum has a continuous web of spacer sheet material on both sides (between the opening and the duct). around its edges by a defined area) to prevent leakage.

As a result of the first, second and third inventions, it has become possible to achieve much higher purity than ever before. For example, if a salt with a concentration of 30,000 ppm is dissolved in the initially diluted water, it has been difficult or impossible in practice to reduce the final diluted concentration to less than about 1,500 ppm using an appropriate electrodialysis method. However, in the first, second, and third aspects of the present invention, it is possible to easily lower the dilute concentration to 300 ppm or less, for example, 30 ppm. Therefore, the first, second and third
According to the invention, it is possible to reduce the impurity concentration by at least 1/50, usually by 1/100, often by at least 1/500, and in some cases by 1/1000 or 1/2000 by dialysis or electrodialysis. It can be done easily.

The purpose of including at least one laterally protruding portion with respect to a closed slot is that if the slot is moved laterally relative to its cooperating slot, each slot is rectangular and the same width as the open end. The objective is to be able to provide a larger continuous passageway compared to the previous one. Generally, each slot projects in both directions with respect to its open end, making the slot, for example, triangular, T-shaped, keyhole-shaped, or the like. However, it is possible to obtain sufficient results by making the slot protrude only in one lateral direction to form an L-shape, or in some cases by cutting the slot at an angle of 90° or less to the edge of the duct or opening. I can do it. If the cooperating slot of the spacer assembly is provided with an enlarged portion projecting in only one direction, it is preferred that the slot of the cooperating sheet is provided with an enlarged portion projecting in the opposite direction.

Generally, the enlarged portion of a slot is enlarged with respect to its open end as a result of being wider than its open end. This configuration has the advantages already mentioned in connection with slot misalignment, and even when the slots are perfectly aligned, it is possible to reduce the amount of space formed by cooperating slots compared to sheets with rectangular slots. The pressure drop that occurs along the fluid path is also lower. Preferably, the width of the enlarged portions of the slots is greater than the width of the web of sheet material located between the enlarged portions. This is because a continuous fluid path is inevitably created regardless of the lateral position of the spacer sheets with respect to each other. Preferably, the maximum width of the slot is 1.2 to 5 times the width of the open end of the slot, and generally 1.5 to 3.0 times the width of the open end of the slot. The open end of each slot is usually 0.5 to 5.0 mm wide, preferably 1 to 3 mm wide. If overlapping of slots occurs, the slots are usually 2 to 10 mm in the slot extension area.
The width is preferably 3 to 5 mm.

Although it is desirable that the width of the web material between the slot extensions be less than the width of each slot extension, it should not be too narrow. If this is too narrow, the sheet will be weakened and the teeth formed by adjacent slots may tear during handling of the spacer sheet. Preferably, the width is at least 1.5 mm, usually 2.5 mm or more.

The spacer sheet is suitably formed from a thin flexible sheet material such as a plastic material.
Preferred plastic materials include ethylene and propylene homopolymers or copolymers thereof, polyvinyl chloride, polyolefin, and the like. Preferably, the spacer sheet is formed from polypropylene. The thickness of the sheet is generally 0.2~3
mm range, preferably 0.5 to 1.5 mm.
The resistance of the sheet to bending and indentation into the slot is determined in part by the ratio of the thickness of the sheet to the width of the slot. In normal cases, the ratio of the thickness of the spacer sheet to the width of the opening end of the slot is 1:5 to 5:
1, preferably in the range of 1:2 to 1:0.3.

Ducts for supplying or withdrawing fluid from the openings are disposed along opposite sides of the spacer sheet. Advantageously, each duct comprises one or more substantially rectangular holes formed over substantially the entire width of the opening in the spacer sheet. Slots are preferably provided substantially evenly along each duct. Also, for best results, the spacing of the slots in the two spacer sheets forming the spacer assembly should be substantially the same. Some degree of irregularity in slot size, spacing, etc. is acceptable as long as it does not make the flow through the cells extremely uneven.
Because the slots are distributed over substantially the entire width of the duct and the opening, a cell containing this spacer assembly has flow distribution across the entire width of the chamber formed by the opening. substantially equal. Particularly in electrodialysis cells, it is necessary to maintain a constant flow throughout the diaphragm.
This is because the loss of flow increases the concentration of ions on the surface of the membrane, resulting in, for example, a change in pH or the precipitation of the most harmful salts. Maintaining an even flow across the diaphragm also results in improved efficiency in transporting species through the diaphragm.

The spacer sheets are advantageously shaped as polygons with an even number of sides, such as rectangles, and are preferably regular polygons, such as hexagons or, most suitably, squares. The ducts on two opposing sides of the polygon form part of the passageway for supplying and withdrawing the first fluid passing through the cell. Book 1,
For example, the square spacer sheet according to the second and third inventions is preferably provided with a side channel that is substantially the same size and position as the duct between the opening on the non-ducted side and the outer edge of the spacer. These side channels form part of the passageway that supplies and withdraws the cell's second fluid. The same spacer assembly can be used in adjacent fluid chambers to allow different fluids to flow thereat at right angles to each other. Also in such cells the spacers are oriented at 90° with respect to each other. The bypass of one spacer assembly thus forms, together with the duct of the other spacer, part of the supply and withdrawal passage for fluid into the chamber formed by the opening of the latter spacer assembly. . Similarly, identical hexagonal spacer assemblies with ducts on two opposing sides and side channels on the other four sides can be used in fluid separation cells with three separate flows. . The spacer assembly is then oriented at 60° with respect to the spacer between adjacent septa.

In a preferred spacer assembly, each spacer sheet is substantially identical, but the slot arrangement is such that one sheet is unique with respect to the same sheet.
When turned and/or rotated by 180°,
It is necessary to ensure that the slots opening into the ducts in one sheet cooperate with the slots opening into the openings in the other sheet.

The opening of each sheet may be completely open, or
It may also include a baffle configured to direct fluid through a non-linear path between the supply duct and the recovery duct.

It is preferred that each spacer assembly, and indeed the entire fluid separation cell, be removably held by compressive force and need not be secured with glue, glue, or the like. The laminate may be held by bolts passing through holes in the spacer and the diaphragm, or plates may be placed on both ends of the laminate and held together by bolts.

A conventional mesh spacer may be placed in each chamber between the pair of septa. Depending on the system, particles or fibers of ion exchange resin may be present in the chamber.
Other particles or fibers may also be included. In that case, it is advantageous to prevent the particles from leaving the room by placing a fine wire mesh layer between the two spacer sheets forming the spacer to close the passage.

The first, second, and third inventions are particularly useful for cells for electrodialysis, but are also effective for dialysis such as hemodialysis, ultrafiltration, particularly low pressure ultrafiltration, crossflow microfiltration, etc. . The pressure difference between adjacent chambers
Even if the pressure is as large as 3.5 bar, leakage can be prevented.

The dilute liquid and concentrated liquid used in the first, second and third inventions may be liquids conventionally used in such treatments. When performing electrodialysis, both the dilute solution and the concentrated solution are usually aqueous, and the dilute solution is often water contaminated with dissolved salts, and the concentrated solution is often impure water such as seawater.

There are also various situations in which it is desirable to remove ions dissolved in a mixture of water and water-miscible organic liquids. Various fluids are pumped into underground wells at various stages in the recovery of hydrocarbons, e.g. gas and oil, and some of these fluids are so expensive that it is desirable to recirculate them. It often contains ingredients. For example, when fluid is recovered from an underground well, such as a submarine well, the fluid may be diluted with water, typically seawater. Therefore, it is necessary to remove water before recycling the fluid to maintain the concentration of the fluid components. If the contaminant is seawater, salt deposits will often form as a result of removal by distillation or other evaporative processes. Therefore, it is necessary to remove the dissolved salts before performing evaporation, and to do so in a manner that does not damage other components of the fluid.

Special problems arise when extracting methane and other highly volatile hydrocarbons.
If water leaks into the compressed stream of methane, solid hydrated methane deposits may form, resulting in valve blockage. It is therefore necessary to inject a water-miscible solution, i.e. methanol but generally ethylene glycol, into the methane stream to absorb any water leakage and prevent the formation of such deposits. a. However, especially with respect to subsea oil and gas wells, the difficulty of concentrating makes it economically very difficult to maintain the concentration of organic liquid for reuse. the result,
If seawater leaks into a gas well, it is better to shut it down immediately than to try to stop it by adding ethylene glycol and then concentrating the resulting aqueous ethylene glycol mixture. There are many cases where it is better to do so.

The inventors have made the surprising discovery that electrodialysis can be used to remove dissolved ions from mixtures of water and water-miscible liquids. Although electrodialysis can be performed using a well-known electrodialysis cell, it is preferable to use the electrodialysis cells according to the first, second, and third aspects of the present invention as described above. According to this method, the salt concentration can be easily lowered from, for example, 20,000 ppm to a value below 500 ppm, and caking of the evaporator is prevented.

In a preferred method, the deionized liquid is concentrated by removing at least some of the water;
The resulting concentrate of water-miscible organic liquid is pumped into an underground well. Water is generally removed from the deionized liquid by flash evaporation.

Desirably, the water-miscible organic liquid is resistant and inert to ions, particularly sodium and chloride ions. Suitable organic liquids are glycols, especially monoethylene glycol.

Various components can be included in the aqueous mixture for specific down hole applications. This method is particularly useful for recycling water and glycol mixtures as protective bath fluids for downhole tools and for gas recovery. This solution is diluted downhole with seawater and deionized to obtain the desired concentration mixture before water is removed by flash evaporation. For example, the first, second and third inventions can be applied to remove sodium chloride from a 50-50 by weight glycol and water mixture containing up to 5% sodium chloride. The resulting deionized glycol solution can be concentrated and used for gas recovery, for example as a 70-30% by weight glycol and water mixture.

Electrodialysis cells generally have two input streams, one of which is the aqueous organic dilute solution to be deionized;
The other consists of water or seawater concentrate. Ions are transferred from the aqueous organic solution to water or seawater through an electrodialysis membrane. The membrane will normally be substantially impermeable and inert to the nonionic, ie, organic, components of the mixture. A small portion of the cell output is recirculated to the input so that liquid flows through the cell.
More than one pass often improves the efficiency of deionization.

Because the solution is generally recovered and recycled from the well, gases and other hydrocarbons that the solution collects from the well can be separated from the solution before returning it to the well. Although this separation may occur after the electrodialysis step, it is usually done before passing the solution through the electrodialysis cell. For example, gases and/or light hydrocarbons can be distilled from a solution recovered from a well with a mixture of glycol and water.

Next, the first, second and third inventions will be explained in more detail with reference to the drawings.

A pair of identical spacer sheets 1 are used to configure the spacer assembly, each of which has an opening 2 and
A duct formed by two rectangular holes 8, 9, and two holes 10,
11, a hole 12 for retaining the bolt, and a pair of slots 13, 14 (drawn to scale). The duct formed by hole 8 is a type 1 duct as defined above, and the duct formed by hole 9 is a type 2 duct.

One of the holes 8 and 9 constitutes a fluid supply duct, and the other of the holes 8 and 9 constitutes a fluid discharge duct.

The holes 8 are provided along one of the two opposite sides of the spacer sheet 1 and the holes 9 are provided along the other of the two opposite sides of the spacer sheet 1.

The illustrated slots 13 and 14 each have a narrow open end 30 opening into either the duct holes 8 and 9 or the opening 2, and an extension 31 including an enlarged portion 32. The side parts 33, 34 of this enlarged part are respectively arranged to project laterally with respect to the open end 30. The sheet material between the slots 13 forms teeth 15 which join the continuous web 20 at the closed end of the slot extension, while the sheet material between the slots 14 forms teeth 16. 2, which joins the continuous web 21 behind the closed end of the slot 14. Continuous webs 18, 19 separate opening 2 from the bypass formed by holes 10, 11.

A spacer assembly is formed by rotating two spacer sheets 1 by 180° relative to each other. Within one cell, diaphragms 17 are arranged on either side of the spacer assembly, with openings 2 in the spacer sheets forming continuous webs 18, 19 along opposite sides of the spacer and continuous webs 18, 19 along opposite sides of the spacer. A chamber surrounded by webs 20, 21 is created.

The keyhole-shaped slots 13 and 14 are connected to each web 20,
21 and overlap along the longitudinal centerline of the webs 20, 21 in the region of their widenings 32. Overlapping slots 13 and 14
duct 8 or 9 and spacer sheet 1 for each pair
arrow 2 between the chamber formed by the opening 2 of
A continuous fluid passageway is formed as shown at 3.

When the seat 1 is properly positioned as shown in FIG. 2, the widened portions 32 of the slots 13 and 14 coincide exactly to form the widest possible passageway 23.
If the seat 1 is misaligned as shown in FIG. 3, the slots 14 will align with the teeth 15 between the slots 13, and the slots 13 will align with the teeth 16 between the slots 14. However, since the diameter of enlarged portion 32 is greater than the width of the tooth at its narrowest point, slots 13 and 14 still form a continuous fluid passageway into and out of the chamber.

Spacer pairs and diaphragms are alternately stacked in the cell stack. As shown in FIG.
7 are kept apart at their peripheries by spacer sheets, and the relatively narrow width of the slot extensions 31 substantially eliminates the risk of adjacent spacer sheets invading into the slots. ing.
As a result of pressing against the periphery of the laminate by the retaining bolts in holes 12, each diaphragm is provided with a continuous web of undistorted spacer sheet on both sides, all around the opening of the spacer assembly and around all ducts and sideways. Leakage is eliminated or minimized between contact and fluid flow.

The illustrated spacer sheet is for use in a two-flow system such as that described in British Patent No. 845,186. The system is configured such that one stream flows alternately through chambers between the membranes and the other stream flows perpendicularly to each other through separate chambers. An example of such a configuration is shown in the exploded view of FIG. 7, which shows one assembly, which can be repeated to complete a complete stack.

Between each pair of diaphragms 17 there is a spacer assembly 35 each consisting of two spacer sheets 1.
a, 35b are arranged. The two spacer sheets of one spacer assembly are both identical, but one sheet is rotated 180° with respect to the other sheet about an axis passing through the center of its plane and perpendicular to it.
or by 180° with respect to the other sheet about an axis passing parallel to and intermediate between the fluid supply ducts or the recovery ducts as fluid discharge ducts formed by the holes 8,9. The spacer assemblies of adjacent chambers 35a and 35b are identical to each other, but rotated 90 DEG with respect to each other about an axis passing through the center of their plane and perpendicular thereto. A mesh sheet is typically disposed within the chamber formed by the opening 2 of the spacer sheet of the spacer assembly, but has been omitted from the illustration for clarity.

A septum 17 between each pair of spacer assemblies
As shown in FIG. 6, they are mutually the same, and passages are formed by holes 8a to 11a and bolt holes 12a that coincide with holes 8 to 11 and bolt holes 12 of the adjacent spacer sheets, respectively. .

For clarity, FIG. 7 only shows one direction of flow through the cell. The fluid supply duct passage is (in order from the bottom) hole 1 of the first diaphragm 17a.
0a, a bypass formed by holes 11 and 10 in spacer sheet 1 forming first spacer assembly 35a, respectively, and hole 10a in second diaphragm 17b. It is formed by the diaphragm bypass and the passage formed by holes 9 and 8, respectively, in the spacer sheet forming the second spacer assembly 35b. Similarly, the fluid discharge duct passage is also connected to the hole 11 of the diaphragm 17a.
a, a bypass formed by holes 10 and 11 in 35a, a bypass formed by hole 11a in diaphragm 17b, and assembly 3.
5b by the passage formed by holes 8 and 9.

A rigid continuous web 18,1 between the holes 10,11 and the side channels formed by the openings 2a, 2b.
9 prevents liquid of the input and output streams from entering the chamber formed by the openings 2a and 2b of each sheet of the assembly 35a between the diaphragms 17a and 17b. The input flow liquid is
Slots 13 and 1 as shown by arrow 23 in FIG.
4 through the diaphragm 17a adjacent to the diaphragm 17b.
(not shown) into the chamber formed by openings 2c and 2d in each sheet of spacer assembly 35b. This liquid passes through the chamber as indicated by arrow 36 and is discharged along the opposite edge of the chamber via slots 14 and 13 in a direction opposite to arrow 23 in FIG. 5 to form part of the output stream. Becomes a department.

The diaphragm and spacer stack may be retained by retaining bolts passing through holes 12 and 12a. The pressure applied by the bolts seals the spacer sheet and the diaphragm along the flat continuous webs 18-21 of the spacer sheet, thereby minimizing leakage without the use of adhesives. Since the laminate can be easily disassembled and assembled, even if the diaphragm is damaged, it can be easily replaced.

The illustrated spacer can also be applied to three or more flow systems by increasing the number of polygonal sides of the spacer and diaphragm. In this case, two sides of the polygon are used for each flow, preferably two opposite sides as two opposite sides. Hexagonal spacers and diaphragms can also be used, for example as a three-flow system with acid, alkali and waste streams.

The remainder of the cell structure is conventional apart from the novel spacer assembly. Thus, for specific dialysis, electrodialysis, and other required purposes, conventional diaphragms may be used, followed by the provision of appropriate electrodes and electrode compartments in the case of electrodialysis. Generally, the width of each side of the cell is 300mm to 3m,
For a square cell like the one shown, the width of each side is set to normal.
300-1200mm, often 500 or 1000mm, most preferably about 500mm. Therefore the actual slot 1
The numbers 3 and 14 are typically much larger than the numbers shown in the figure.

The first invention will be explained with the following example.

A dilute solution containing monoethylene glycol and seawater at a mixing ratio of 50/50 was desalted by electrodialysis using a cell configured with a spacer and diaphragm shown in FIG. 7 and seawater as a concentrate. The dissolution rate of salt in dilute solution was varied between 30000 and 40000 ppm. These solutions were circulated through the stack at a flow rate of approximately 16/min to achieve the desired dissolved solids concentration of less than 300 ppm. This shows that there is virtually no leakage. This is because if there is a leak, the lowest level of desalination that can be achieved is 1500 ppm. A current efficiency of 80-90% was achieved at a voltage of 1.5 V for a pair of cells.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a spacer sheet, Figure 2 is an enlarged diagram showing a slot that forms a passage in a spacer assembly with two spacer sheets aligned, and Figure 3 is an enlarged view of a spacer assembly with two spacer sheets aligned incorrectly. FIG. 4 is a cross-sectional view taken along line - of FIG. 2 showing the spacer assembly and the chamber containing the diaphragm; FIG. 5 is a close-up view of the spacer assembly of FIG. 6 shows a diaphragm for use with the spacer of FIG. 1, and FIG. 7 shows a diaphragm for use with the spacer of FIG. FIG. 7 is an exploded view of a portion of a cell assembly for two-way feed flows flowing at right angles to each other using the diaphragm of FIG. 6; 1... Spacer sheet, 2... Opening, 8,
9, 10, 11... hole, 12... hole, 13, 14
...Slot, 17, 17a, 17b...Diaphragm,
18, 19, 20, 21...continuous web, 23...
...Passage, 30...Opening end, 32...Enlarged portion, 35
a, 35b...Spacer assembly.

Claims (1)

[Scope of Claims] 1. A spacer assembly for separating diaphragms of a fluid separation cell, the spacer assembly including a pair of spacer sheets, each of which has a central portion arranged in the center thereof to accommodate a fluid. an aperture provided along one of two opposing sides of the spacer sheet for supplying the fluid into the interior of the aperture; and a substantially width of the aperture; a fluid supply duct extending entirely along the other of the two opposing sides for discharging the fluid supplied to the opening to the outside of the opening; a fluid discharge duct extending over substantially the entire width of the opening; and a fluid discharge duct opening into either the fluid supply duct or the opening, the fluid supply duct opening into either of the fluid supply duct and the opening, the one of the fluid supply ducts of the opposite sides; a plurality of first slots substantially uniformly spaced across a width and each extending part way between the fluid supply duct and the opening; and and are arranged at substantially uniform intervals across the width of the fluid discharge duct on the other side of the opposing sides, and the gap between the fluid discharge duct and the opening is substantially uniform. a plurality of second slots each extending halfway between the spacer sheets, and the opening in one of the pair of spacer sheets and the first slot opening into one of the fluid supply ducts said opening in the other of the pair and said first slot opening into the other of said fluid supply duct to respectively form a first fluid passageway between said opening and said fluid supply duct; and the second slot, which opens into one of the opening in the one pair of spacer sheets and the fluid discharge duct, connects the opening in the other pair of spacer sheets with the other of the fluid discharge duct. each of the first slots forming a second fluid passageway between the opening and the fluid discharge duct; some of the pairs each have an enlarged portion at the closed end of the at least one of the first pair of slots, each having an enlargement projecting to at least one side with respect to at least one of the first pair of slots; Some of said second pairs of slots forming a second fluid passage include an enlarged portion projecting to at least one side with respect to at least one of said second pairs of slots. A spacer assembly for separating membranes of the fluid separation cell, each having a spacer assembly at the at least one closed end. 2. The spacer according to claim 1, wherein substantially all of the first slots are each provided with the enlarged portion, and substantially all of the second slots are each provided with the enlarged portion. assembly. 3. The enlarged part is formed to protrude on both sides of each of the first slot and the second slot, and each of the enlarged part and the slot has a keyhole shape or a T-shape, The ratio of the width of the enlarged portion to the respective widths of the first slot and the second slot is 1.2:1.
Claim 1 within the range of 5.0:1 from
The spacer assembly according to item 1 or 2. 4. The enlarged part is formed to protrude on both sides of each of the first slot and the second slot, and each of the enlarged part and the slot has a keyhole shape or a T-shape, The ratio of the width of the enlarged portion to the respective widths of the first slot and the second slot is 1.5:1.
Claim 1 within the range of 3.0:1 from
The spacer assembly according to item 1 or 2. 5. A spacer assembly according to any one of claims 1 to 4, wherein the width of the enlarged portion is greater than the width of the spacer sheet defined between two adjacent slots. 6. The width of each of the first slot and the second slot is in the range of 0.5 mm to 3 mm,
Each of said spacer sheets is 0.5mm to 3mm
6. A spacer assembly according to any one of claims 1 to 5, having a thickness in the range of . 7. The ratio of the width of each of the first slot and the second slot to the thickness of each of the spacer sheets is in the range of 0.2:1 to 5:1. A spacer assembly according to any one of the above. 8. The ratio of the width of each of the first slot and the second slot to the thickness of each of the spacer sheets is in the range of 0.3:1 to 2:1. A spacer assembly according to any one of the above. 9 Each of the spacer sheets has a regular polygonal shape with an even number of sides, and the fluid supply duct and the fluid discharge duct are provided on the side portions that do not have the fluid supply duct and the fluid discharge duct. 9. A spacer assembly according to any one of claims 1 to 8, wherein a bypass is provided having substantially the same dimensions and location as the duct. 10. The spacer assembly of claim 9, wherein each of said spacer sheets is square. 11. A spacer assembly according to any one of claims 1 to 10, wherein each of the spacer sheets is formed from a sheet of a thermoplastic material selected from the group consisting of polyolefins. 12 The first slot and the second slot are respectively selected from a first type slot opening into one of the fluid supply duct and the fluid discharge duct and a second type slot opening into the opening. A spacer assembly according to any one of claims 1 to 11. 13. Each of the spacer sheets has a slot of the first type and a slot of the second type, and the first type of slot of one of the spacer sheets is connected to the slot of the other of the spacer sheets. 13. A spacer assembly as claimed in claim 12 cooperating with said second type of slot. 14 A fluid separation cell formed by alternately stacking diaphragms and spacer assemblies, wherein the spacer assemblies each include a pair of spacer sheets, each of which accommodates a fluid. an opening provided in the center of the spacer sheet to supply the fluid into the opening; and an opening provided along one of two opposing sides of the spacer sheet to supply the fluid into the opening , a fluid supply duct extending over substantially the entire width of the opening; a fluid discharge duct extending along substantially the entire width of the opening; and opening into either the fluid supply duct or the opening, the opposing sides a plurality of first slots arranged at substantially uniform intervals across the width of the one of the fluid supply ducts and each extending part way between the fluid supply duct and the opening; , open to either the fluid discharge duct or the opening, and are arranged at substantially uniform intervals across the width of the fluid discharge duct on the other side of the opposing side; a plurality of second slots each extending part way between the fluid discharge duct and the opening, the second slot opening into the opening in one of the pair of spacer sheets and one of the fluid supply duct; A first slot cooperates with the opening in the other of the pair of spacer sheets and the first slot opening into the other of the fluid supply duct to form a first slot between the opening and the fluid supply duct. the opening in the one of the pair of spacer sheets and the second slot opening into one of the fluid discharge ducts respectively forming one fluid passageway in the other of the pair of spacer sheets; a second fluid passageway is formed between the opening part and the fluid discharge duct in cooperation with the second slot opening into the other of the opening part and the fluid discharge duct; Some of said first pairs of slots forming said at least one pair of slots have an enlarged portion projecting on at least one side with respect to at least one of said first pair of slots. each of the second pairs of slots having at each end, some of the pairs of second slots forming the second fluid passageway having enlarged portions projecting to at least one side with respect to at least one of the pairs of second slots; , a fluid separation cell formed by alternating stacks of diaphragms and spacer assemblies, each having a closed end of said at least one of said second pair of slots. 15. each of the spacer assemblies is square and of substantially the same size;
15. Claim 14, wherein mutually adjacent spacer assemblies are oriented substantially 90° with respect to each other, and the cell is configured such that two fluid streams pass through the cell. cell for fluid separation. 16 A spacer sheet used in a spacer assembly that separates a diaphragm in a fluid separation cell, comprising: an opening provided in the center of the spacer sheet to accommodate a fluid; and a spacer sheet for containing the fluid inside the opening. a fluid supply duct disposed along one of two opposing sides of said spacer sheet and extending substantially across the width of said opening for supplying said opening; a fluid discharge duct provided along the other of the two opposing sides and extending over substantially the entire width of the opening for discharging the fluid to the outside of the opening; and opening into either the fluid supply duct or the opening, and arranged at substantially uniform intervals across the width of the one of the fluid supply ducts on the opposing sides; , a plurality of first slots each extending halfway between the fluid supply duct and the opening, and a plurality of first slots opening in either the fluid discharge duct or the opening, and opening in the opposing side portions. a plurality of second slots arranged at substantially uniform intervals across the width of the other fluid discharge duct and each extending partway between the fluid discharge duct and the opening; some of said first slots have an enlarged portion projecting on at least one side with respect to each of said plurality of first slots at a respective closed end of said plurality of first slots; some of said second slots have an enlarged portion projecting on at least one side with respect to each of said several second slots; A spacer sheet used in a spacer assembly that separates diaphragms in a fluid separation cell.