WO2006089460A1 - An electric desalination method and a spiral winding electric desalination device - Google Patents

Abstract

The present invention discloses an electric desalination method and a spiral winding electric desalination device. The method makes use of the cross flow of the brine and the fresh water. The brine flows in the axial direction, and the fresh water flows in the radial spiral direction. The revelant device of realizing the method comprises a central tube as one pole of the electrodes and a shell homocentric with the central tube on which the other pole of the electrodes is placed on. Several cation and anion exchange membranes are placed alternately surround the center tube to separate the space between the center tube and the shell to brine chambers and fresh water chambers. Ion exchange resin is filled in the fresh water chamber. The membranes are rolled up axled around the central tube. The membrane bags formed by the said membranes have two edges each of which opening to another, the fresh water inlet is located on the shell and the outlet of which is located on the central tube. This kind of module has good desalination effect and can reduce the possibility of scaling.

Description

 Electric demineralization method and structure of spiral coil type electric desalter

 The present invention relates to an electric desalter, and more particularly to a method and structure for a spiral coil electric desalter which is designed to be more advantageous for desalination. Background technique

 In the existing water treatment method for desalination and purification of industrial water, a more advanced method is to combine electrodialysis technology and ion exchange technology to prepare ultrapure water, that is, electric desalination (EDI) technology. EDI technology is the removal or concentration of ions by the selective permeation of anion and cation in solution by an anion-cation exchange membrane under the action of a direct current electric field. A typical electric desalination apparatus generally includes positive and negative electrodes, alternating anode and cathode ion exchange membranes between the positive and negative electrodes, and an electrode chamber, a concentrated water chamber and a fresh water chamber separated by a cation membrane. The water to be treated enters the fresh water chamber. Under the action of the ion exchange resin and the current, the charged ions in the water migrate toward the anode and the cathode, respectively, and the positively charged ions migrate toward the cathode, and enter the concentrated water from the fresh water chamber through the cation exchange membrane. room. Similarly, the negatively charged ions migrate toward the anode and pass through the anion exchange membrane from the fresh water chamber to the concentrated water chamber. The ions entering the concentrated water chamber will continue to move in the original migration direction, but due to the selective permeation characteristics of the ion exchange membrane, the cation exchange membrane only allows the passage of cations, and the anion exchange membrane only allows the passage of anions, so in concentrated water The ions in the chamber can no longer be returned to the fresh water chamber. This achieves the goal of purifying the water in the fresh water chamber.

In the EDI component, the order of the various ions in the fresh water is different. The first is High-priced ions are eluted, followed by low-cost, easily eluted ions, and finally weakly ionized ions, hydrogen ions, and hydroxide ions are removed. The current (density) required for the removal of various ions is also different, the current required for the easy removal of ions is low, and the current required for the weak ionization to remove ions is high. Therefore, the preferred component design should be that the current at the freshwater influent is relatively low, while the current at the freshwater effluent is relatively high to facilitate the removal of ions that are difficult to deionize for weak ionization.

 The water in the fresh water chamber also undergoes a cracking reaction under the action of electric current, especially at the interface of the ion exchange resin and the ion exchange membrane at the outlet end of the EDI component with high purity of water, which is prone to water cracking reaction. The cleavage reaction produces hydrogen ions and hydroxide ions which regenerate the ion exchange resin. Therefore, the EDI technique is a process of continuously regenerating an ion exchange resin without using an acid or a base.

 Electric desalination technology has been widely used in the preparation of pure water in the fields of semiconductor, pharmaceutical, power and food. The electric desalination module has a plate-and-frame design and a roll-type design, wherein the roll-type EDI component has a concentric roll type and a spiral roll type.

However, in existing electric desalination devices, particularly in plate and frame EDI assemblies, the water flow in the fresh water and concentrated water chambers is generally co-directional or concurrent (as shown in Figure 1). 1 is a concentrated water chamber, 2 is a fresh water chamber, and 3 and 4 are polar water chambers, respectively. 5 is concentrated water into the water, 6 is fresh water into the water. 7 is the positive electrode and 8 is the negative electrode. 9 and 10 are polar water inflows, respectively. 11 is a cation exchange membrane, and 12 is an anion exchange membrane. 13 is concentrated water, 14 is fresh water, 15 and 16 are polar water. An ion exchange material such as an ion exchange resin is added to the module fresh water chamber, and the concentrated water chamber and the polar water chamber are filled with an ion exchange material such as an ion exchange resin or an inert support grid. In this design, Ca ⁺⁺ and Mg ⁺⁺ migrate from the fresh water chamber through the cation exchange membrane 11 to the concentrated water chamber 1, as shown in Figure 1, this migration occurs at the inlet end of the assembly, When they enter the concentrated water chamber, they will continue to move toward the cathode under the action of current, and at the same time they will move toward the outlet end of the assembly with the flow of water. When Ca ⁺⁺ and Mg ⁺⁺ reach the anion exchange membrane 12, they cannot pass back to the fresh water chamber 2 through the anion exchange membrane 12, and as a result they will flow out of the assembly with concentrated water.

 On the other hand, some hydrogen ions and hydroxide ions generated by the water cracking reaction, as well as weakly ionized ions such as bicarbonate and carbonate ions, also enter the concentrated water chamber through the ion exchange membrane, and hydrogen ions in the concentrated water chamber. It combines with hydroxide ions to form water. However, on the side surface of the concentrated water chamber of the cation exchange membrane 11, since the local hydrogen ion concentration is high, it exhibits strong acidity. On the side surface of the concentrated water chamber of the anion exchange membrane 12, since the concentration of the local hydroxide and the hydrogencarbonate and the carbonate ion is high, it exhibits a strong basicity. The thickness of this surface layer depends on the flow of concentrated water. When the flow of concentrated water is severe, the thickness of the surface layer is thin. When the flow of concentrated water is small, the thickness of the surface layer is thick.

In the existing electric desalination device, the side of the anion exchange membrane concentrated water chamber is close to the outlet end of the module, and the Ca ⁺⁺ and Mg ⁺⁺ ions blocked by the anion exchange membrane will be combined with hydroxide, bicarbonate and carbonate. Combined, precipitation precipitates are produced.

Ca ⁺⁺ +OH"→ Ca (OH) ₂ \ Mg ⁺⁺ +OH - Mg (OH) ₂ \

Ca ⁺⁺ +C0 ₃ —→CaC0 ₃ \ Mg ⁺⁺ +C0 ₃ ——→MgC0 ₃ \

Ca ⁺十+HC0 ₃ ——— Ca(HC0 ₃ ) ₂ I Mg ⁺⁺ +HC0 ₃ —→ Mg(HC0 ₃ ) ₂ \ And in the existing electric desalination process, the concentrated water circulation operation process is generally adopted, With the operation of the device, the concentration of Ca ⁺⁺ and Mg ^{++ in the} concentrated water is getting higher and higher, which further aggravates the severity of scaling. Scaling will not only affect the normal operation of the ion exchange membrane, but also increase the resistance of concentrated water flow and reduce the flow of concentrated water. After the flow rate is reduced, the hardness is lowered due to the decrease in the water flow rate. Ions such as Ca ⁺⁺ and Mg ⁺⁺ do not flow out of the concentrated water chamber in time, which also exacerbates fouling. As a result, a vicious cycle is formed, which affects the desalination performance and service life of the components, resulting in a decrease in water production capacity.

 For example, there are Chinese patents CN2327675Y, CN2394705Y and USP6, 190, 528B1, which report a spiral wound electric desalter, which provides a spiral-type electric desalter water treatment device, which mainly uses yin and yang. The ion exchange membrane and the insulating mesh separator are made into a special membrane bag type concentrated water flow channel unit, and communicate with the side wall of the concentrated water distribution pipe, and each adjacent concentrated water flow channel unit forms a chargeable ion exchange resin. The fresh water flow channel unit is then wound into a cylindrical structure centered on the concentrated water distribution pipe, and then wrapped with a metal electrode and a casing. Thus, the fresh water flow path is in the same direction as the central concentrated water distribution pipe, and the concentrated water flow path is spirally extended from the central concentrated water distribution pipe to the module outer casing. The utility model has the advantages of simple structure, reasonable sealing method of components, high use pressure, and replacement of ion exchange resin. However, in this configuration, the respective flow paths of the fresh water flow path are spiral in a section perpendicular to the axial direction of the module. In addition, the current density is different at each position in the section perpendicular to the axial direction of the component, and the current density is calculated as follows:

D!=I/S ( 1 ) where: D [- current density, A/cm ²

 1-current, A

Area of the S-fresh water channel membrane surface, cm ³

Obviously, the current density near the central tube of the component is high, while the current density is low near the component housing. In this way, the current density at each point of the freshwater flow is different in the cross section perpendicular to the flow direction of the fresh water, the current density is high near the central tube of the assembly, and the current density is low near the outer casing of the module. Unevenness of the current density distribution, thereby It leads to the difference in the desalination ability of fresh water. The desalination ability of fresh water is the weakest near the outer shell of the module. The closer to the central tube of the module, the stronger the desalination ability of fresh water, which makes it possible in all parts of the device. Fresh water quality has produced differences.

 U.S. Patent No. 5,376,253, the entire disclosure of which is incorporated herein by reference in its entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire The flow pattern is spiraled to effluent at the center electrode of the assembly. In this structure, the current density at the fresh water inlet is high, and the current density at the effluent is high, which is advantageous for the weak ionization of the difficult to remove ions. However, in this patent, the flow direction of concentrated water and fresh water is parallel in parallel flow, so that it is easy to scale in the concentrated water chamber, especially at the outlet end of the concentrated water, and the hardness of the fresh water inflow is strict. In addition, in this design, the influent and effluent of fresh water and concentrated water are completed by the influent distribution pipe and the water collecting pipe. Due to structural limitations, especially the limitation of the central pipe, the structure generally has only one pair of fresh water. And the concentrated water chamber, that is, only one anion-cation exchange membrane bag is rotated to the bottom, so that only the axial length can be increased to ensure the water production of the device, so that the water production of the module is limited, or the pressure of fresh water and concentrated water is lowered. high. Also, in this design, the ion exchange resin of the fresh water chamber cannot be replaced, so that the use range is limited and the operation cost is increased. Finally, the assembly is complex in manufacturing process and difficult to maintain and replace parts, so the assembly is costly to manufacture.

DISCLOSURE OF THE INVENTION The present invention mainly provides a spiral wound electric desalter with a reasonable structure, good desalination ability of components, and reduced possibility of scale formation; and solves the uneven distribution of current density existing in the prior art, producing water Technical problems with low quality and easy scaling of components.

The above technical problem of the present invention is mainly solved by the following technical solutions: The electric desalination method of the spiral coil type electric desalter is to use the flow direction of concentrated water and fresh water to be interlaced, the concentrated water flows axially, and the fresh water spirals in a radial direction. The corresponding spiral coil electric desalter of the present invention has the following structures: a central tube as a pole of the electrode and a concentric outer casing, and the other pole of the outer casing provided with electrodes, which are arranged alternately around the central tube a plurality of anion-cation exchange membranes, the space between the central tube and the outer casing is divided into a concentrated water chamber and a fresh water chamber by an anion-cation exchange membrane, the fresh water chamber is filled with an ion exchange resin, and a pair of anion-cation exchange membranes form a membrane pocket to the central tube The anion-cation exchange membrane is wound into a core for the axial center, and the membrane bag formed by the anion-cation exchange membrane is open at opposite ends, the fresh water inlet is disposed on the outer casing, and the water outlet is disposed on the central tube. Fresh water flows in from the inlet of the outer casing, where the current density is the lowest, and the ions removed from the fresh water here are first expensive and easily deionized, and the current required to remove such ions is also low. When the fresh water flows in the direction of the central tube in a spiral manner, the current density received is also increasing, and the current required to remove the ions in the fresh water is also increasing. Finally, in the area near the central tube of the module, the fresh water needs to be removed. The ions are mainly weakly ionized, difficult to remove anions, such as bicarbonate ions, carbonate ions and organosilicon ions, etc., to remove the high currents required by these ions, and the current density there is also The highest value has been reached, which meets the requirements for the removal of difficult ions. The flow of fresh water from the outside to the inside increases the current acting on fresh water from low to high, which just meets the current requirements for the removal of ions, thereby enhancing the desalination capacity of the components and improving the components. Electrical efficiency optimizes component performance and energy consumption. Fresh water is the flow direction of the radial spiral, and concentrated water is the axial flow direction. The two water flows form a cross form, which reduces the hydroxide and bicarbonate at the water outlet of the Ca ⁺⁺ and Mg ⁺⁺ ions and the concentrated water chamber. The opportunity to meet carbonate, which reduces the fouling of the concentrated water chamber Capability.

 Preferably, the film bag is open in the radial direction, closed in the axial direction, the outside of the film bag is a concentrated water chamber, the inside of the film bag is a fresh water chamber, and the opening of the film bag is divided into several, the central tube is hollow The integrated straight pipe has a plurality of openings corresponding to the central pipe, and the opening is connected to the fresh water flow channel unit.

 Preferably, the opening of the film bag is open between the two ends of the film bag, and the openings of the plurality of film bags near the outer casing end are joined together to be connected with the fresh water inlet of the outer casing.

 Preferably, the central pipe is sleeved with a water distribution plate, and the water distribution plate is provided with a hollow support plate; the inner side of the support plate is provided with a fresh water inlet at a position opposite to the opening of one end of the film bag, and the outer side of the support plate The outer casing is provided with a concentrated water inlet, and the concentrated water outlet is disposed at the other end of the outer casing axial direction.

 Preferably, the film bag is open in the axial direction, closed in the radial direction, the fresh water chamber is outside the film bag, and the concentrated water chamber is in the film bag, the central pipe has a concentrated water inlet at one end and fresh water at one end. The nozzle is closed on the side of the central water inlet of the concentrated water.

 Preferably, a concentrated water distribution device is arranged at the concentrated water inlet of the central pipe, and the concentrated water distribution device is provided with a plurality of concentrated water distribution holes in the circumferential direction of the concentrated water inlet of the central pipe, The water cloth water hole is connected with a cloth water passage, the cloth water passage is provided with a plurality of through holes, the cloth water passage is connected with a cloth water chamber, and the cloth water chamber is provided with a water distribution board and a baffle plate on both sides, the cloth water board is close to On the side of the film bag, the water distribution plate and the baffle plate are sleeved on the center tube.

Preferably, the barrier plate is provided with a fresh water inlet passage, and the fresh water inlet passage is connected to the circumferential freshwater inlet of the outer casing side. Preferably, the fresh water chamber is provided with a sealing strip in the axial direction, and a filling hole is arranged thereon, and a sealing plug is connected to the filling hole.

 Preferably, the outer casing is provided with a water outlet.

 Therefore, the present invention has the actual desalination condition when the raw water flows through various sections of the electric desalter, and fully utilizes the characteristics of different current density inside and outside the electric desalter, so that the requirements of current and ion removal are consistent, and the structure is reasonable. The arrangement is scientific, the water flow resistance is small, and the deep desalination of the raw water is realized, especially the removal of the weak electrolyte is greatly improved, the quality of the produced water is improved, and the use efficiency of the electric energy is improved.

 At the same time, due to the cross-flow design of fresh water and concentrated water, the possibility of scaling can be effectively reduced, thereby increasing the water production and ion exchange performance, and the hardness of fresh water influent can be relatively increased, and the electric desalter is extended. The service life. DRAWINGS

 Figure 1 is a schematic view of the flow direction of a parallel flow of a coiled electric desalter.

 Fig. 2 is a general view of a fresh water chamber in a film bag of a spiral wound electric desalter according to the present invention.

 Figure 3 is a cross-sectional view of a thick water passage of a spiral wound electric desalter of the present invention. Fig. 4 is a general view of a concentrated water chamber in a film bag of a spiral wound electric desalter according to the present invention.

Fig. 5 is a schematic view showing the structure of a concentrated water distribution device in a membrane bag of a spiral wound electric desalter according to the present invention. Fig. 6 is a schematic view showing the sealing of the fresh water chamber of the concentrated water chamber in the membrane bag of the spiral wound electric desalter of the present invention. Best way to implement the invention

 The technical solutions of the present invention will be further described in detail below by way of embodiments and with reference to the accompanying drawings.

 Embodiment 1: As shown in FIG. 2, the spiral coil type electric desalter is centered on the center tube 17, the center tube 17 is an engineering plastic tube, and the surface is coated with a titanium-coated thin plate as a cathode of the electrode, and the outer casing 18 As the anode electrode, the two electrodes are provided with a DC power source; a plurality of anion-cation exchange membranes are arranged alternately around the center tube 17, and the space between the center tube 17 and the outer casing is divided into a concentrated water chamber 1 and fresh water by an anion-cation exchange membrane. Room 2, the fresh water chamber 2 is filled with ion exchange resin, and a pair of anion and cation exchange membranes form a membrane pocket filled with an insulating mesh separator, and an insulating mesh separator is also disposed outside the membrane pocket, an anion exchange membrane and insulation The mesh separators are alternately arranged, and the anion-cation exchange membrane and the mesh separator are integrally formed by the central tube 17 as an axis, and a water collecting plate and a water distribution plate are respectively disposed on the upper and lower sides of the anion and cation membrane. The film bag is a fresh water chamber 2, and the outside of the film bag is a concentrated water chamber 1. The film bag is sealed in the axial direction, and the film bag is directly open on both sides in the radial direction, and the opening of the film bag is in the radial direction, one end It is connected to the water inlet of the outer casing 8, and one end is connected to the water outlet of the central pipe 17. A concentrated water outlet 13 is arranged outside the water collecting plate at the upper end of the outer casing 18, and a concentrated water inlet 5 is arranged outside the water discharging plate at the lower end of the outer casing, and fresh water is arranged at the inner side of the water discharging plate at the lower end of the outer casing and the opening of the anion exchange membrane bag. The water inlet 6 flows out of the film bag after flowing through the film bag.

Fresh water flows in from the water inlet 6 on the outer casing side, and flows spirally through the anion-cation exchange membrane bag. The outlet of the heart tube 17 is well utilized, and the external current density is weak. First, the strong ion is removed. When the fresh water flows near the center tube, the internal current density is strong, and it is suitable for removing the weak ion. The present invention The insufficiency of the density difference between the inner and outer rings of the coil type electric desalter is well utilized, and a design suitable for the ion removal process of the coil type electric desalter is provided.

 At the same time, the concentrated water flows axially from the outside of the membrane bag, and the flow direction of the concentrated water and the fresh water is substantially at an angle of 90 °, thereby effectively reducing the possibility of scaling, thereby improving the water production and ion exchange performance, and prolonging the electric desalination. The service life of the device (Figure 3).

Embodiment 2: As shown in FIG. 4, the spiral coil type electric desalter is centered on the center tube 17, the center tube 17 is an engineering plastic tube, and the surface is coated with a titanium-coated thin plate, and the cathode is used as an electrode. As the anode electrode, the two electrodes are provided with a DC power source; six pairs of anion-cation exchange membranes are arranged alternately around the center tube 17, and the space between the center tube 17 and the outer casing 18 is divided into a concentrated water chamber by an anion-cation exchange membrane. And the fresh water chamber 2, the fresh water chamber 2 is filled with ion exchange resin, and a pair of anion and cation exchange membranes form a membrane pocket, the number of membrane pockets is straight through the membrane pocket, the opening direction is axial, radial sealing, membrane pocket The inside is a concentrated water chamber 1, the thickness of which is 1. 5mm, outside the membrane bag is a fresh water chamber 2, the concentrated water chamber 1 is filled with an inert structural material such as a grid, and the fresh water chamber 2 is filled with an anion-cation exchange resin, the thickness of which is 5 mm, with the center tube 17 as the axis, which is spirally wound into a cylinder. As shown in FIG. 3, one end of the central pipe 17 · is a concentrated water inlet 5, and one end is a fresh water outlet 14 , and two partitions are provided between the concentrated water inlet 5 and the fresh water outlet 14 . The tube 17 is partitioned into a hollow straight-through hollow tube; a concentrated water distribution device is arranged at the concentrated water inlet 5, and the concentrated water distribution device is radially arranged in the circumferential direction of the concentrated water inlet 5 of the central tube 17. a concentrated water cloth water hole 19, and a water distribution channel 20 is connected to the cloth water hole 19, and the concentrated water inflow of the water distribution channel 20 The cloth water chamber flows into the concentrated water chamber 1 through the water distribution plate 21, since the film bag is a straight axial opening, and the fresh water chamber 2 is provided with a sealing strip in the axial direction, and the concentrated water can only enter the thick water after flowing through the water distribution plate 21. In the water chamber 1, the concentrated water flows directly in the axial direction, flows out over the membrane bag, and flows out of the electric desalter through the concentrated water outlet 13 on the outer casing 18; as shown in Fig. 5, the fresh water flows in from the water inlet 6 of the outer casing 18, The baffle 22 on the other side of the water supply chamber is encountered, the water flows into the circumferential fresh water inlet 6 on the side of the outer casing, and the fresh water flows spirally from the side of the outer casing 18 into the side of the central pipe 17, since the membrane bag is radially closed, The fresh water collecting device on the central pipe 17 collects fresh water, and the fresh water collecting device uniformly distributes fresh water collecting holes 23 on the central pipe of the fresh water outlet, through which the fresh water collects fresh water after demineralization by the electric desalter Fresh water flows out through the central pipe 17, and both ends of the fresh water chamber 2 are closed by a sealing strip, and a filling hole is arranged thereon, and a sealing screw 24 is connected to the filling hole, and the filling and replacement of the ion exchange resin is realized through the filling hole (if attached) Figure 6); polar water on the side of the outer casing 18 Collection means to collect the water outlet through the electrode 25 provided on the housing outer desalination effluent.

 The fresh water flows in from the water inlet 6 on the side of the outer casing 18, and spirally flows through the anion-cation exchange membrane to the fresh water outlet 14 of the center pipe 17. The concentrated water flows upward from the lower direction of the assembly along the axial direction of the assembly. The flow direction of concentrated water and fresh water is at an angle of 90°, forming a cross-flow flow (see Figure 3).

When the fresh water flows in the fresh water chamber, the current density of the current acting on it is different. In the fresh water inlet region, that is, near the module outer shell, the current density is low; as the fresh water flows in a spiral manner toward the center tube, The current density of the current acting on it is also continuously increased; when fresh water flows close to the central tube region, the current density of the current acting thereon is maximized. This change in current density matches the removal order of the ions to be removed in the fresh water. In the fresh water inflow region, the first is the removal of high-priced easily removed ions. The required current density is also low; when fresh water flows close to the exit region, the ions to be removed in the fresh water are weakly ionized and difficult to remove ions, and the current density required to remove these ions is also high. The roll type electric desalter in the invention utilizes the characteristics of uneven current density distribution, improves the desalination performance of the module, and particularly improves the removal ability of the weak ionization, and also the ability to remove ions. Improve the efficiency of energy use and reduce energy consumption. In addition, since the flow of fresh water and concentrated water is carried out in a cross-flow manner, the possibility of scale formation in the concentrated water chamber is effectively reduced, thereby relaxing the requirement of the module for the hardness of the fresh water inlet, and also prolonging the electric desalter. The service life reduces the operating cost of the components.

 Example 3: The desalination test was carried out using the roll type electric desalter in Example 2, and the roll type electric desalter proposed in USP 6,190,528 B1 was used as a comparative test component. The test conditions are as follows, and the test results are shown in Table 1.

Freshwater production water flow 2M ³ /hr

 Freshwater intake conductivity 40 S/cm

 Fresh water inlet temperature 25 ° C

 Concentrated water conductance 400- 45 (^S/cm

 Fresh water influx H 6. 2

 Recovery rate 90%

 Table 1 Desalination test results

 Component Number Voltage, V Current, A Freshwater Product Water Resistivity, ΜΩ. cm Example 2 93. 5 5. 0 17. 6

Comparison component 96. 0 8. 0 11. 6 Example 4: A silicon stripping test was carried out using the coiled electric desalter proposed in Example 2 and USP 6,190,528 B1. The test conditions are as follows, and the test results are shown in Table 2.

表 2 有机硅脱除测试结果 Freshwater production water flow 2M ³ /hr Freshwater intake water conductivity 25 S/cm Freshwater inlet water temperature 25°C Concentrated water conductivity 400-450 S/cm Freshwater influent pH 8.0 Recovery rate

Table 2 Silicone removal test results

Component No. Voltage, ν Current, A Influent Silicon Concentration Water Resistance Silicon Removal Degree, ppb Rate, ΜΩ. cm

Example 2 58.0 6.0 253 18.0 96.2 Comparison component 60.0 6.0 249 17.9 82.4 Example 2 59.5 6.0 478 17.9 95.1 Comparison component 60.0 6.0 480 17.7 79.3

Claims

Rights request  A method for electric desalination of a spiral wound electric desalter, characterized in that the flow directions of concentrated water and fresh water are mutually staggered, the concentrated water flows axially, and the fresh water spirals in a radial direction.  2. A spiral wound electric desalter structure comprising a central tube (17) as a pole of an electrode and a concentric outer casing (18), and another pole having an electrode on the outer casing (18), with a central tube (17) a plurality of anion-cation exchange membranes arranged alternately in the center, and the space between the central tube (17) and the outer casing (18) is divided into a concentrated water chamber (1) and a fresh water chamber (2) by an anion-cation exchange membrane. The fresh water chamber (2) is filled with an ion exchange resin, and a pair of anion-cation exchange membranes form a membrane pocket, and the anion-cation exchange membrane is integrally wound with the central tube (17) as an axis, and the yin and yang are described. The membrane bag formed by the ion exchange membrane is vented at opposite ends, the fresh water inlet (5) is disposed on the outer casing (18), and the water outlet (13) is disposed on the central tube (17). ' The spiral coil type electric desalter structure according to claim 2, wherein the film bag is opened in a radial direction, closed in an axial direction, and a concentrated water chamber outside the film bag (1) The film bag is a fresh water chamber (2), and the opening of the film bag is divided into several. The center tube (17) is a hollow integrated straight pipe, and the center pipe (17) is distributed with a plurality of openings corresponding thereto. The opening is connected to the fresh water flow channel unit.  The spiral coil type electric desalter structure according to claim 2, wherein the film bag is open in the axial direction, closed in a radial direction, and the fresh water chamber (2) is outside the film bag. Inside the membrane bag is a concentrated water chamber (1), the central tube (17) is terminated by a concentrated water inlet (5), one end is a fresh water outlet (14), and the central tube (17) is a concentrated water inlet (5) ) - side closure. 5. A spiral wound electric desalter structure according to claim 2 or 3, wherein The sign is that the film bag is open between the two ends of the film bag, if the film bag is close to the outer casing (18) The openings at the ends are joined together and connected to the fresh water inlet (6) on the casing (18).  The spiral coil electric desalter structure according to claim 5, wherein: the central pipe (17) is sleeved with a water distribution plate (21), and the water distribution plate (21) is externally There is a hollow support plate; the inner side of the support plate is opposite to the opening of one end of the film bag, and a fresh water inlet (6) is provided, and the outer casing (18) of the support plate is provided with a concentrated water inlet (5), The water outlet (13) is placed at the other end of the outer casing (18) in the axial direction.  The spiral coil electric desalter structure according to claim 2 or 4, characterized in that: a concentrated water distribution device is arranged at the concentrated water inlet (5) of the central pipe (17), The concentrated water distribution device is provided with a plurality of concentrated water distribution holes (19) in the circumferential direction of the concentrated water inlet (5) of the central pipe (17), and the concentrated water distribution hole (19) is connected with the water distribution channel. (20), the water channel (20) is provided with a plurality of through holes, the water distribution channel is connected with a water distribution chamber, and both sides of the water distribution chamber are provided with a water distribution plate (21) and a barrier plate (22), the cloth The water plate is close to the film bag side, and the water distribution plate (21) and the baffle plate (22) are sleeved on the center tube (17).  8. The spiral coil electric desalter structure according to claim 7, wherein: the baffle (22) is provided with a fresh water inlet channel, and the fresh water inlet channel is connected to the outer casing. (18) The fresh water inlet in the circumferential direction of the side (6). '  The spiral coil type electric desalter structure according to claim 8, wherein: the fresh water chamber (2) is provided with a sealing strip in the axial direction, and a filling hole is formed thereon, and is filled A sealing plug is attached to the hole. 10. A spiral wound electric desalter structure according to claim 2 or 3 or 4, The utility model is characterized in that: the outer casing (18) is provided with an extreme water outlet (25).