Anion exchange resin mixed with ion exchange resin and separation and regeneration method of cation exchange resin

Abstract

According to the separation and regeneration method for the anion exchange resin and the cation exchange resin mixed with the ion exchange resin, a separation tower, a cation exchange resin regeneration tower and a concentrated alkali specific gravity separation tower are included. In the separation step in the separation tower, the anion exchange resin and the cation exchange resin are separated. The separated anion exchange resin is conveyed to a concentrated alkali specific gravity separation tower, the mixed cation exchange resin is separated and removed by using a high-concentration NaOH aqueous solution having an intermediate specific gravity between the anion exchange resin and the cation exchange resin, and regeneration treatment is performed. In addition, the cation exchange resin separated in the separation step in the separation tower is conveyed to a cation exchange tower, and an HCl solution is injected to regenerate the cation exchange resin. The method for separating and regenerating the anion exchange resin and the cation exchange resin by mixing the ion exchange resin enables the separation of the anion exchange resin and the cation exchange resin to be carried out with high precision by a concentrated alkali specific gravity separation method without increasing the initial cost.

Description

Technical Field

[0001] The present invention relates to a method for separating and regenerating an anion exchange resin and a cation exchange resin used in a non-regenerative ion exchange device, a mixed bed ion exchange device, etc., which are used in a pure water production device, etc. Background Art

[0002] In a pure water manufacturing device, impurities in raw water are removed to improve the cleanliness of water. A mixed bed ion exchange device filled with anion exchange resin and cation exchange resin is usually used to remove ionic impurities, i.e., anionic impurities and cationic impurities. In the mixed bed ion exchange device, if the ions of the ion exchange resin equivalent to the ion exchange capacity are exchanged, more ionic impurities cannot be removed and penetration occurs. Therefore, after a certain degree of treated water is treated, the ion exchange resins are respectively recovered from the mixed bed ion exchange device, and then regenerated with hydrochloric acid, caustic soda, etc. in the cation exchange resin regeneration tower and the anion exchange resin regeneration tower for reuse. At this time, usually, water is passed in an upward flow manner and the difference in sedimentation velocity caused by the difference in specific gravity between the anion exchange resin and the cation exchange resin is used to separate the anion exchange resin from the cation exchange resin.

[0003] An example of a separation column of the mixed ion exchange resin is shown in Figure 4 .exist Figure 4 In the separation tower 21 of the mixed ion exchange resin, a water injection and discharge port 22 is provided at the bottom of the cylindrical separation tower body 21A, and a water supply pipe 23 as a water outlet having a plurality of spray nozzles 23A is provided, and a drain port 24 is formed at the top. A water collecting plate 25 is arranged below the spray nozzle 23A of the separation tower body 21A. In addition, an anion exchange resin extraction pipe 26 as an anion exchange resin extraction part is provided near the middle of the vertical direction in the separation tower 21, and a cation exchange resin extraction pipe 27 is provided below the anion exchange resin extraction pipe 26 and slightly above the water supply pipe 23. In addition, an observation window 28 is formed on the side of the separation tower 21. In addition, 29 is an inlet for the used mixed ion exchange resin provided on the upper side of the side of the separation tower 21.

[0004] In the separation tower 21 of the mixed ion exchange resin, the used mixed ion exchange resin is put into the separation tower 21, and then, a 4 wt% NaOH aqueous solution is passed through it. After being left for a predetermined time, pure water is injected from the injection and discharge water port 22 and the NaOH aqueous solution in the separation tower is squeezed out from the drain port 24 for washing. Then, the separation tower 21 is filled with a predetermined amount of separation water (pure water). At this time, the water surface of the separation water is higher than the upper surface of the mixed ion exchange resin, especially at an upper position of about 500 mm or less.

[0005] Then, air is injected into the separation tower from the injection and discharge water port 24 to bubble the mixed ion exchange resin, and the bubbling is stopped after the resin particles entangled in a colloid state are untied, so that the mixed ion exchange resin is settled on the water collecting plate 25. At this time, the cation exchange resin with a larger specific gravity settles first, and the anion exchange resin with a smaller specific gravity settles later. Then, in order to prepare for backwashing, pure water (separation water) is introduced from the injection and discharge water port 22 to fill the separation tower 21 with water.

[0006] In this water-filled state, pure water is sprayed from the spray nozzle 23A and water is passed in an upward flow, and the separation interface is adjusted to the lower end of the suction port of the anion exchange resin extraction pipe 26 while visually checking from the observation window 28. Then, suction is performed from the anion exchange resin extraction pipe 26, so that the anion exchange resin flows out and is taken out in the form of a mixed phase flow of the anion exchange resin and water. After the water is removed from the mixed phase flow of the anion exchange resin and water, it is transported to the anion exchange resin regeneration tower to perform the regeneration treatment of the anion exchange resin.

[0007] After the anion exchange resin is extracted in this way, pure water is continuously ejected from the ejection nozzle 23A while suction is taken from the cation exchange resin extraction pipe 27 so that it flows out and is taken out in the form of a mixed phase flow of the cation exchange resin and water. After the mixed phase flow of the cation exchange resin and water is dehydrated, it is transported to the cation exchange resin regeneration tower to regenerate the cation exchange resin. At this time, the cation exchange resin is not completely taken out, but is left to a certain extent, thereby preventing the mixing of the anion exchange resin.

[0008] However, in the above-mentioned separation method of anion exchange resin and cation exchange resin, there is a problem that the separation of the two is insufficient. In particular, the cation exchange resin can be well separated by leaving the interface portion in the separation tower 21, but there is a problem that the cation exchange resin is easily mixed into the anion exchange resin extracted initially.

[0009] Therefore, the concentrated alkali specific gravity separation method (Seprex method) is used, which uses a high concentration of NaOH aqueous solution to separate anion exchange resin and cation exchange resin. Figure 5 Process as shown.

[0010] That is, using the aforementioned Figure 4 The separation tower 21 shown is Figure 5 After the anion exchange resin is extracted in the separation process (first separation process) as shown, it is transported to a special tower for separating the cation exchange resin mixed in the anion exchange resin (concentrated alkali specific gravity separation tower (Seprex tower)). Then, in the state of injecting a NaOH aqueous solution of an intermediate specific gravity between the specific gravity of the anion exchange resin and the specific gravity of the cation exchange resin into the concentrated alkali specific gravity separation tower, the resin is disentangled by bubbling and allowed to stand, so that the mixed cation exchange resin is allowed to settle to the lower side, and the cation exchange resin is extracted and removed from the lower part of the concentrated alkali specific gravity separation tower. In addition, pure water is supplied to the tower, and after squeezing out the NaOH aqueous solution and washing, the residual anion exchange resin is extracted (second separation process). The extracted anion exchange resin is transported to the anion exchange resin regeneration tower and the anion exchange resin is regenerated and washed by conventional methods. On the other hand, the cation exchange resin separated in the first separation process is transported to the cation exchange resin regeneration tower and the cation exchange resin is regenerated and washed by conventional methods. Summary of the invention

[0011] Problems to be solved by the invention

[0012] By using the concentrated alkali gravity separation method as described above, an anion exchange resin and a cation exchange resin can be separated with very little mixing of the other. Figure 5 As shown, four towers are required, namely, a separation tower, an anion exchange resin regeneration tower, a cation exchange resin regeneration tower, and a concentrated alkali specific gravity separation tower. This not only increases initial cost but also increases the number of operation steps such as the ion exchange resin transport step.

[0013] The present invention has been made in view of the above problems, and its object is to provide a method for separating and regenerating anion exchange resin and cation exchange resin of a mixed ion exchange resin, which can accurately separate anion exchange resin and cation exchange resin by concentrated alkali specific gravity separation without increasing initial cost.

[0014] Means for solving problems

[0015] In view of the above-mentioned purpose, the present invention provides a method for separating and regenerating an anion exchange resin and a cation exchange resin of a mixed ion exchange resin, which is a method for separating and regenerating anion exchange resin and cation exchange resin from a mixed ion exchange resin of anion exchange resin and cation exchange resin, wherein the method for separating and regenerating anion exchange resin and cation exchange resin of a mixed ion exchange resin comprises: a separation step, in which the mixed ion exchange resin is put into a roughly cylindrical separation tower of mixed ion exchange resin having a mixed ion exchange resin input part, an anion exchange resin extraction part arranged in the middle of the up-down direction, a cation exchange resin extraction part arranged below the anion exchange resin extraction part, and an air and separation water injection part arranged at the bottom, separation water is introduced into the separation tower in an upward flow manner from the air and separation water injection part, and the mixed ion exchange resin is separated by using a specific gravity difference; a conveying step, in which the mixed ion exchange resin is extracted from the anion exchange resin extraction part and the cation exchange resin is extracted below the anion exchange resin extraction part. The invention further comprises the following steps: removing the anion exchange resin on the upper side of the separation interface with the cation exchange resin and conveying it to the anion exchange resin separation and regeneration tower, and extracting the residual cation exchange resin from the cation exchange resin extraction part and conveying it to the cation exchange resin regeneration tower; an anion exchange resin separation and regeneration step, in which the anion exchange resin is immersed in a NaOH aqueous solution of 5 wt % or more and 30 wt % or less in the anion exchange resin separation and regeneration tower, separating the cation exchange resin mixed in the anion exchange resin, discharging the cation exchange resin, and regenerating the anion exchange resin; an anion exchange resin washing step, in which the anion exchange resin remaining in the anion exchange resin separation and regeneration tower is washed with water; a cation exchange resin regeneration step, in which the cation exchange resin in the cation exchange resin regeneration tower is regenerated in the cation exchange resin regeneration tower; and a cation exchange resin washing step, in which the cation exchange resin remaining in the cation exchange resin regeneration tower is washed with water (Invention 1).

[0016] According to the above invention (Invention 1), the cation exchange resin mixed in the anion exchange resin separated by the separation tower is put into the anion exchange resin separation and regeneration tower, and the NaOH aqueous solution with the intermediate specific gravity between the anion exchange resin and the cation exchange resin is injected, and the cation exchange resin mixed in the anion exchange resin is separated by using the specific gravity difference, and the anion exchange resin is regenerated, so that the functions of the concentrated alkali specific gravity separation tower and the regeneration tower of the anion exchange resin can be exerted in one tower, and therefore, the structure of three towers can be adopted instead of the structure of four towers like the previous concentrated alkali specific gravity separation tower. Thus, the anion exchange resin and the cation exchange resin can be separated with good accuracy by using the concentrated alkali specific gravity separation method without increasing the initial cost.

[0017] In the above invention (Invention 1), it is preferred that the anion exchange resin and the cation exchange resin are porous ion exchange resins (Invention 2).

[0018] According to the above invention (Invention 2), the specific gravity of the NaOH aqueous solution of 5% by weight or more and 30% by weight or less can be set between the specific gravity of the porous anion exchange resin and the specific gravity of the porous cation exchange resin. Therefore, the cation exchange resin mixed in the anion exchange resin can be appropriately separated by utilizing the specific gravity difference.

[0019] Effects of the Invention

[0020] According to the method for separating and regenerating anion exchange resin and cation exchange resin of a mixed ion exchange resin of the present invention, an aqueous NaOH solution having a specific gravity intermediate between anion exchange resin and cation exchange resin is injected into anion exchange resin easily mixed with cation exchange resin in an anion exchange resin separation and regeneration tower, the cation exchange resin mixed in the anion exchange resin is separated by utilizing the specific gravity difference, and the anion exchange resin is regenerated, thereby being able to separate anion exchange resin and cation exchange resin with good accuracy without increasing the initial cost in a three-tower structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a process diagram showing a method for separating and regenerating an anion exchange resin and a cation exchange resin of a mixed ion exchange resin according to the first embodiment of the present invention.

[0022] Figure 2 This is a process diagram showing a method for separating and regenerating an anion exchange resin and a cation exchange resin of a mixed ion exchange resin according to a second embodiment of the present invention.

[0023] Figure 3This is a process diagram showing a method for separating and regenerating an anion exchange resin and a cation exchange resin of a mixed ion exchange resin in Comparative Example 1.

[0024] Figure 4 This is a schematic diagram showing an example of a separation column of a mixed ion exchange resin including an anion exchange resin and a cation exchange resin.

[0025] Figure 5 This is a process diagram showing a method for separating and regenerating an anion exchange resin and a cation exchange resin of a mixed ion exchange resin by a conventional concentrated alkali gravity separation method. DETAILED DESCRIPTION

[0026] Hereinafter, the method for separating and regenerating an anion exchange resin and a cation exchange resin of a mixed ion exchange resin of the present invention will be described in detail with reference to the drawings.

[0027] [First embodiment]

[0028] [Configuration of separation and regeneration system of mixed ion exchange resin]

[0029] The separation and regeneration method of the anion exchange resin and the cation exchange resin of the mixed ion exchange resin of the present invention is as described above. Figure 4 As shown, it is composed of three towers: a separation tower, a cation exchange resin regeneration tower, and a concentrated alkali specific gravity separation tower (anion exchange resin separation / regeneration tower).

[0030] (Mixed ion exchange resin)

[0031] In this embodiment, the mixed ion exchange resin is a mixed resin of anion exchange resin and cation exchange resin. The ratio (volume ratio) of anion exchange resin to cation exchange resin in the mixed ion exchange resin is not particularly limited, and anion exchange resin: cation exchange resin = about 30:70 to 70:30.

[0032] The anion exchange resin and cation exchange resin are preferably porous ion exchange resins. The porous anion exchange resin has a specific gravity of about 1.03 to 1.09 g / mL (when wet), and the porous cationic exchange resin has a specific gravity of about 1.22 to 1.30 g / mL (when wet).

[0033] [Method for separation and regeneration of anion exchange resin and cation exchange resin of mixed ion exchange resin]

[0034] Then, based on Figure 1 The flowchart of FIG. 1 illustrates the separation and regeneration method of the mixed ion exchange resin according to the present embodiment using the apparatus having the above-described structure.

[0035] (Separation process)

[0036] For the separation process, Figure 5 The separation process is the same as in , so its detailed description is omitted.

[0037] (Separation and regeneration process of anion exchange resin)

[0038] A small amount of cation exchange resin is mixed in the anion exchange resin taken out in the separation step. Therefore, the following operation is performed in the concentrated alkali specific gravity separation tower.

[0039] First, after an anion exchange resin is added to the concentrated alkali specific gravity separation tower, an aqueous NaOH solution is injected. The aqueous NaOH solution is set to have a concentration of 5 to 30% by weight and a specific gravity intermediate between the anion exchange resin and the cation exchange resin. For example, when the anion exchange resin and the cation exchange resin are porous, the aqueous NaOH solution has a concentration of 9 to 25% by weight. The aqueous NaOH solution has a specific gravity of about 1.10 to 1.27 g / mL.

[0040] Then, air is injected into the concentrated alkali specific gravity separation tower from the injection and discharge water port, and the anion exchange resin is bubbled for a predetermined time and then stopped and allowed to stand, thereby allowing the anion exchange resin to settle. In this settling, the NaOH aqueous solution is set to have an intermediate specific gravity between the anion exchange resin and the cation exchange resin, so that only the cation exchange resin with a large specific gravity settles.

[0041] In this state, the cation exchange resin is sucked from the cation exchange resin extraction pipe provided at the bottom of the concentrated alkali specific gravity separation tower, and the cation exchange resin is flowed out and extracted in the form of a mixed phase flow of cation exchange resin and water. After the mixed phase flow of cation exchange resin and water is dehydrated, it can be put into the mixed ion exchange resin at the next separation and regeneration.

[0042] Then, pure water is supplied to the concentrated alkali specific gravity separation tower, the NaOH aqueous solution in the tower is squeezed out and discharged, and the anion exchange resin is washed. Then, after the pure water is discharged from the concentrated alkali specific gravity separation tower, the NaOH aqueous solution (concentration of about 4 weight %) is introduced again to regenerate the anion exchange resin, and then pure water is supplied to the concentrated alkali specific gravity separation tower, the NaOH aqueous solution in the tower is squeezed out and discharged, and the anion exchange resin is washed. In this way, the anion exchange resin can be regenerated. The regenerated anion exchange resin is taken out from the tower and reused.

[0043] (Cation exchange resin regeneration process)

[0044] In the cation exchange resin regeneration tower, the same operation as in the conventional method is performed: First, after the cation exchange resin is put into the cation exchange resin regeneration tower, the HCl solution as the inorganic acid is injected to regenerate the cation exchange resin.

[0045] Then, pure water is supplied to the cation exchange resin regeneration tower, the HCl solution in the tower is squeezed out and discharged, and the cation exchange resin is washed. In this way, the cation exchange resin can be regenerated. The regenerated cation exchange resin is taken out from the cation exchange resin regeneration tower and reused.

[0046] In this embodiment as above, the separation of the cationic exchange resin mixed in the anionic exchange resin and the regeneration of the anionic exchange resin are carried out in the concentrated alkali specific gravity separation tower, therefore, the separation and regeneration of the anionic exchange resin and the cationic exchange resin can be carried out by the system of three tower structures. In addition, owing to adopting three towers to operate, therefore, the operation process can also be reduced.

[0047] [Second Embodiment]

[0048] The method for separating and regenerating an anion exchange resin and a cation exchange resin of a mixed ion exchange resin according to the second embodiment is as follows: Figure 2 The process shown is carried out.

[0049] This embodiment is similar to the first embodiment described above, in which the anion exchange resin separated in the first separation step is immersed in a high concentration NaOH aqueous solution to separate the mixed cation exchange resin, and after the extraction step is completed, the subsequent regeneration using the NaOH aqueous solution is completed by immersing it in a high concentration NaOH aqueous solution, and only extrusion and washing with the NaOH aqueous solution using pure water are performed.

[0050] As in this embodiment, in the separation and regeneration process of the anion exchange resin, by performing the separation of the anion exchange resin and the mixed cation exchange resin and the regeneration of the anion exchange resin in one process, the workability can be further improved compared with the first embodiment described above. In addition, the amount of NaOH aqueous solution used can be reduced.

[0051] The present invention is described in more detail by the following specific examples.

[0052] [Example 1]

[0053] The device is composed of a separation tower of mixed ion exchange resin, a cation exchange resin regeneration tower and a concentrated alkali specific gravity separation tower. Figure 1The process shown is used to separate, purify and regenerate anion exchange resin and cation exchange resin. As anion exchange resin, a porous anion exchange resin with a specific gravity of 1.05 g / mL (when wet) is used, as cation exchange resin, a porous cation exchange resin with a specific gravity of 1.28 g / mL (when wet) is used, and as the aqueous NaOH solution for separation in the concentrated alkali specific gravity separation tower, a 16 wt % aqueous NaOH solution (specific gravity 1.18) is used.

[0054] Through the separation and purification of Example 1, the mixing rate of the anion exchange resin and the cation exchange resin was 0.005%, and the separation could be performed with extremely high accuracy. In addition, the conversion rate of OH of the anion exchange resin was more than 99%. In addition, the initial cost of the device was about 60 million yen.

[0055] [Example 2]

[0056] The device consists of a separation tower for mixed ion exchange resin, a cation exchange resin regeneration tower and a concentrated alkali specific gravity separation tower. Figure 2 The separation, purification and regeneration of the anion exchange resin and the cation exchange resin were carried out in the same manner as in Example 1 except for the above process.

[0057] Through the separation and purification of Example 2, the mixing rate of the anion exchange resin and the cation exchange resin was 0.005%, and the separation could be performed with extremely high accuracy. In addition, the conversion rate of OH of the anion exchange resin was more than 99%. In addition, the initial cost of the device was about 60 million yen.

[0058] [Comparative Example 1]

[0059] The device is composed of a separation tower of a mixed ion exchange resin, a cation exchange resin regeneration tower and an anion exchange resin regeneration tower, such as Figure 3 As shown, the cation exchange resin mixed in the anion exchange resin was not separated, and only a regeneration process using an aqueous NaOH solution for regeneration was performed to separate, purify and regenerate the anion exchange resin and the cation exchange resin.

[0060] Through the separation and purification of this comparative example 1, the mixing rate of the anion exchange resin and the cation exchange resin was 0.02%, which was higher than that of Examples 1 and 2 and was not suitable for the use of regenerated resins requiring high purity. In addition, the conversion rate of OH of the anion exchange resin was more than 99%. In addition, the initial cost of the device was about 60 million yen.

[0061] [Comparative Example 2]

[0062] The device is composed of a separation tower of a mixed ion exchange resin, a cation exchange resin regeneration tower, an anion exchange resin regeneration tower and a concentrated alkali specific gravity separation tower. Figure 5 The process shown thus performs separation, purification and regeneration of anion exchange resin and cation exchange resin.

[0063] By the separation and purification of this comparative example 2, the mixing rate of each of the anion exchange resin and the cation exchange resin was 0.005%, and the separation could be performed with extremely high accuracy. In addition, the conversion rate of OH of the anion exchange resin was more than 99%. However, the initial cost of the device was about 80 million yen.

[0064] Description of Reference Numerals

[0065] 21: Separation tower of mixed ion exchange resin.

[0066] 21A: separation tower body.

[0067] 22: Inject water into the discharge outlet.

[0068] 23: Water supply pipe.

[0069] 23A: Spray nozzle.

[0070] 24: Drain outlet.

[0071] 25: Water collecting plate.

[0072] 26: Anion exchange resin extraction piping.

[0073] 27: Cation exchange resin extraction piping.

[0074] 28: Observation window.

[0075] 29: Inlet for the used mixed ion exchange resin.

Claims

1. A method for separating and regenerating an anion exchange resin and a cation exchange resin of a mixed ion exchange resin, which is a method for separating and regenerating an anion exchange resin and a cation exchange resin from a mixed ion exchange resin of an anion exchange resin and a cation exchange resin, wherein: The separation and regeneration method of the anion exchange resin and the cation exchange resin of the mixed ion exchange resin comprises: A separation step, in which a mixed ion exchange resin is introduced into a generally cylindrical separation tower of mixed ion exchange resin, which has a mixed ion exchange resin introduction part, an anion exchange resin extraction part provided in the middle of the vertical direction, a cation exchange resin extraction part provided below the anion exchange resin extraction part, and an air and separation water injection part provided at the bottom, and separation water is introduced into the separation tower in an upward flow manner from the air and separation water injection part to separate the mixed ion exchange resin by using a specific gravity difference; a transport step of extracting an anion exchange resin above the separation interface between the anion exchange resin and the cation exchange resin from the anion exchange resin extraction section and transporting the anion exchange resin to an anion exchange resin separation and regeneration tower, and extracting the remaining cation exchange resin from the cation exchange resin extraction section and transporting the residual cation exchange resin to a cation exchange resin regeneration tower; an anion exchange resin separation and regeneration step, in which the anion exchange resin is immersed in a NaOH aqueous solution of 5 wt % or more and 30 wt % or less in the anion exchange resin separation and regeneration tower to separate the cation exchange resin mixed in the anion exchange resin, discharge the cation exchange resin, and regenerate the anion exchange resin; an anion exchange resin washing step, in which water is used to wash the anion exchange resin remaining in the anion exchange resin separation and regeneration tower; a cation exchange resin regeneration step, in which the cation exchange resin in the cation exchange resin regeneration tower is regenerated in the cation exchange resin regeneration tower; and The cation exchange resin washing step is to wash the cation exchange resin remaining in the cation exchange resin regeneration tower with water.

2. The method for separating and regenerating an anion exchange resin and a cation exchange resin of a mixed ion exchange resin according to claim 1, wherein: The anion exchange resin and the cation exchange resin are porous ion exchange resins.

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