JPS602103B2 - Regeneration method of multilayer ion exchange tower - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for regenerating a multilayer ion exchange column, more specifically,
Weak electrolyte ion exchange resin (hereinafter referred to as weak resin).

) in the upper part and a strong electrolyte ion exchange resin (hereinafter referred to as "strong resin") in the lower part.The water to be treated is passed through the tower in the order of ferrite resin to strong resin. The present invention relates to an improved method for regenerating ion exchange resins whose ion exchange function has been reduced by obtaining treated water. In the multi-layer ion exchange method, two types of resin, a strong resin and a weak resin, are packed in the same ion exchange column, and the ion exchange resin layer is arranged in two layers at the neck. It is a method of ion exchange that takes advantage of differences in characteristics such as differences in selective adsorption for ions and differences in regeneration efficiency. Enoki layer ion exchange method is a single layer ion exchange method filled only with strong resin. Compared to conventional methods, when the same regenerant is used, the regenerant utilization efficiency, that is, the equivalent salt ratio of the amount of regenerant used to the amount of ions exchanged, is improved, and less regenerant is required. It has been adopted.

Conventionally, in multilayer ion exchange towers that perform the Enoki bed type ion exchange method, a weak type resin with a low specific gravity is layered on the top and a strong type resin with a high specific gravity is layered on the bottom, and the water to be treated is passed from the top of the column to the bottom of the column. That is, treated water is obtained through a rapid water process in which water is passed in a downward flow from the weak resin to the strong resin to perform ion exchange. After the water passage process, the regeneration process involves regenerating the ion exchange resin whose ion exchange function has decreased. At the same time, the remaining regenerant liquid that is divided is passed downward from the top of the tower to regenerate the weak resin, and the recycled waste liquid that flows out is buried near the interface between the strong resin and the weak resin. For strong resins, a so-called countercurrent regeneration method is used in which the liquid passage and regeneration are performed in opposite directions. In the multi-layer countercurrent regenerated ion exchange tower using this regeneration method, suspended matter brought into the ion exchange tower along with the water to be treated during the water flow process is transferred to the ion exchange resin layer. Due to the accumulation of water, the flow rate of treated water decreases, which has the disadvantage that the amount of treated water decreases. In other words, in the multi-layer countercurrent regenerated ion exchange tower, a regenerated strong resin layer with an ion exchange function that is not ion exchanged and remains near the treated water outlet side of the ion exchange tower after the water flow process is used. If disturbed during the regeneration process, it will cause a decline in the quality of the treated water in the next water flow process. Therefore, in order to wash the ion-exchange resin layer contaminated with suspended matter during the water flow process, washing water flows upward into the tower from the bottom of the column, and the suspended matter is removed together with the washing water. The so-called backwashing operation for discharging outside the column disturbs the recycled strong resin layer, so it was necessary to minimize the amount. Therefore, as the water passing step and the regeneration step are repeated alternately without completely removing suspended matter from the ion exchange resin layer during the regeneration step, the suspended matter gradually accumulates inside the ion exchange resin layer. The pores of the ion exchange resin are reduced, and the ion exchange resin particles become dense and lumpy, resulting in so-called blocking of the ion exchange resin, which increases the pressure loss of the ion exchange resin layer during the water flow process, and reduces the amount of water to be treated. Reduces the amount of water flowing through the
Therefore, the amount of bare water in the treated water is also reduced. Furthermore, in the multi-layer ion exchange method, it is stable to pass the treated water through the weak resin and the strong resin in a state where they are completely separated into two layers, and to pass the regenerant solution through. This is an essential requirement for obtaining high-purity treated water and operating with high regenerant utilization efficiency.

However, weak-type resin undergoes a volume change in which it contracts during the regeneration process and swells during the water-flowing process, while strong-type resin swells during the regeneration process and contracts during the water-flowing process. A difference arises in the packing density of both resin layers.

Therefore, as the weak resin and strong resin, which were initially completely separated into two layers, are subjected to the water passing step and the regeneration step, mixing of both resins occurs near the boundary between the two resins. Furthermore, as mentioned above, in the multilayer countercurrent regeneration ion exchange tower, backwashing operations are minimized during the regeneration process, so backwashing prevents mixing of weak resin and strong resin. As a result, mixing of the weak resin and the strong resin progresses, resulting in a decrease in the quality of the treated water, which also has the disadvantage of reducing the amount of deep water in the treated water. As a method to solve the above-mentioned drawbacks of multilayer countercurrent regeneration ion exchange towers, a backwashing operation is performed during the regeneration process every 20 to 40 times when the water flow process and regeneration process are repeated. After removing suspended solids and separating the weak resin and strong resin into two layers, the ion exchange resin is regenerated using a large amount of regenerating agent solution to eliminate the accumulation of suspended solids. A method of preventing a decrease in the amount of purified water in treated water by adjusting the particle size of the ion exchange resin and using a relatively large particle for the lower strong resin and a comparatively large one for the upper weak resin. By forming an ion exchange resin layer with a large difference in specific gravity between strong and weak resins using particles with small target particles, and preventing mixing of both strong and weak resins, the quality of treated water is prevented from deteriorating and the amount of purified water in treated water is reduced. Methods have been proposed to prevent this, but the regeneration process becomes complicated by adding special operations to the normal regeneration process, or it is not possible to effectively use the ionized fat, and neither of these methods are sufficient solutions. It could not be called a method. Therefore, the present inventor has conducted extensive studies on a method for solving these drawbacks in a regeneration method for a multilayer countercurrent regeneration ion exchange column, and as a result, has arrived at the present invention.

That is, the present invention provides a multi-layer ion exchange tower in which a weak electrolyte ion exchange resin is laminated at the top and a strong electrolyte ion exchange resin at the bottom, and the water to be treated is transferred from the weak electrolyte ion exchange resin to the strong electrolyte ion exchange tower. The amount of treated water required to regenerate the weak electrolyte ion exchange resin when the ion exchange function of the ion exchange resin has decreased by obtaining treated water by passing water through the ion exchange resin in the order of the ion exchange resin. A first step of passing the regenerant solution from the lower part of the strong electrolyte ion exchange resin to the upper part of the weak electrolyte ion exchange resin at a flow rate such that the ion exchange resin flows, and the above treatment at the same flow rate as in the first step. A second step in which water flows in from the lower part of the strong electrolyte ion exchange resin, a third step in which the inflow of the treated water is stopped and the ion exchange resin settles down, and a strong electrolyte ion The fourth step is to discharge the exchange resin from the vicinity of the boundary between the exchange resin and the weak electrolyte ion exchange resin, and then the amount of regenerating agent solution required for regenerating the strong electrolyte ion exchange resin is passed through the lower part of the strong electrolyte ion exchange resin, and the weak electrolyte is removed. A fifth step in which the treated water or the inert gas flows in from the upper part of the trade ion exchange resin, and the recycled waste liquid or recycled waste liquid and the inert gas that flow out are discharged from near the boundary between the strong electrolyte ion exchange resin and the weak electrolyte ion exchange resin. The gist of this paper is a multi-layer ion exchange method for regenerating the nose tower, which is characterized by performing regeneration consisting of the following steps. Hereinafter, the present invention will be explained based on FIG. 1 in comparison with a conventional method.

FIG. 1 shows a schematic cross-sectional view of a multilayer countercurrent regeneration ion exchange tower for carrying out the present invention, in which 1 is an ion exchange tower, and two types of ion exchange resins, namely a weak resin 13, are placed in the upper part of the tower. A strong resin 14 is laminated at the bottom. First, in the water passage process in the conventional method, the water to be treated is passed from the pipe 5 to the valve 21,
Pass through the dispersion pipe 2 and enter inside.

The treated water that has flowed into the tower has been changed from face-shaped resin 13 to strong-shaped resin 1.
4 are connected in this order to undergo ion exchange, and the treated water is taken out as treated water from the lower collector 4 at the bottom of the tank via the valve 25 and pipe 8. This water flow step ends when the water flow is stopped when the purity of the treated water drops to a predetermined value or when a predetermined amount of treated water has been passed through. In the regeneration process, which regenerates the ion exchange resin whose ion exchange function has been reduced due to the water passage process,
First, the regenerant liquid is divided into a regenerant liquid required for regenerating the strong resin and a regenerant liquid required for regenerating the weak resin, and the former is passed from the bottom of the tower through the pipe 9, the valve 27, and the lower collector 4. At the same time, the latter is passed from the pipe 6 through the valve 23 and the dispersion pipe 2 from the connecting part. The recycled waste liquid that flows out is sent to an intermediate collector 3 buried near the boundary between the strong resin 14 and the weak resin 13.
The regeneration process is completed by discharging through the valve 24 and pipe 11. Following the regeneration step, an extrusion step is performed in which the treated water flows into the tower in the same manner as in the regeneration step, and the regenerated waste liquid remaining in the tower is pushed out of the tower. Next, treated water, etc., is flowed into the tower as washing water through the pipe 5, valve 21, and dispersion pipe 2, and is passed through the tower in a downward flow to perform a washing process of washing the ion exchange resin. The waste water is discharged through the lower collector 4, the valve 26, and the pipe 10, and when the purity of the washing waste water near the pipe reaches a predetermined purity, the washing process is completed and the water flow process begins again. In such conventional methods, there is no operation to discharge the suspended matter brought into the tower along with the water to be treated before and after the regeneration process, so each process of liquid passage, regeneration, extrusion, and water washing is As this process is repeated over a long period of time, the voids in the weak resin layer decrease due to these suspended particles, especially in the upper part of the weak resin 13, and the pressure loss during the water passage process increases.

Therefore, the amount of water to be treated is reduced, and the amount of water taken to be treated is also reduced. Furthermore, it is possible to prevent the mixing of both strong and weak resins that occurs near the boundary between the weak resin 13 and the strong resin 14 due to contradictory volume changes of the strong resin and weak resin that occur during the water flow process and the regeneration process. In this case, since stratification separation operation by backwashing operation is not performed, the mixing of both strong and weak resins gradually progresses, resulting in a decrease in the utilization efficiency of the regenerant solution and the quality of the treated water, resulting in a decrease in the amount of deep water in the treated water. resulting in a decrease in On the other hand, in the present invention, the water passing step is performed in the same manner as in the conventional method to obtain treated water.

In the regeneration process after the water to be treated has passed through, first, in the same machine as in the conventional method, the regenerant liquid necessary for regeneration is divided into a regenerant liquid for regenerating weak resin and a regenerating agent liquid for regenerating strong resin. To divide.
Then, the regenerant liquid for regenerating the weak resin is passed from the bottom of the column through the pipe 9, the valve 27, and the lower collector 4 at a flow rate such that the entire ion exchanger resin flows, and the regenerated waste liquid is The first discharged from the dispersion pipe 2, valve 22 and pipe 7 at the top of the column.
The process is carried out. Next, the treated water is passed through pipe 10 and valve 2.
6 and lower collector 4 into the tower at the same flow rate as the regenerant liquid in the first step, and the second step is performed in which the regenerated waste liquid is discharged from the dispersion pipe 2, valve 22, and pipe 7 in the upper part of the tower.
This second step is performed in order to bring the regenerant liquid remaining in the lower strong resin into contact with the upper weak resin, and the amount of treated water to be introduced is equivalent to the amount of the lower strong resin. In the first and second steps, the weak resin 13 in the upper part with good regeneration efficiency is mainly regenerated, and at the same time, the suspended solids that were scooped into the ion exchange resin layer during the water flow step are discharged to the outside of the tower together with the regenerated waste liquid. At the same time, the weak type resin with low specific gravity is layered in the upper part, and the strong type resin with high specific gravity is layered in the lower part. In order to completely separate the layers of the weak resin 13 and the strong resin 14, the flow rate of the regenerant solution should be 4 to 15 minutes, and the drug passing time should be 2 hours.
It is preferable that the heating time is 0 to 30 minutes, and the expansion rate of the ionic resin layer is 50 to 100%.

After the second step, a third step is performed in which the inflow of treated water is stopped to settle and stabilize the flowing ion exchange resin, thereby completing the stratified separation of the weak resin and the strong resin. This third step may be carried out for 10 to 20 minutes. Next, a fourth step is performed in which the regenerated waste liquid remaining in the tower is discharged outside.

Treated water or an inert gas such as air is introduced into the tower through the pipe 6, valve 23, and dispersion pipe 2, and the regenerated waste liquid remaining in the tower is removed near the boundary between the strong resin 14 and the weak resin 13. The liquid is discharged from the valve 24 and the pipe 11 through the intermediate collector 3 installed therein. The discharge rate is preferably 3 to 8/hr. When the discharge of the regenerated waste liquid is completed, the strong resin 14 is regenerated and the fifth step is performed. That is, the regenerating agent liquid for regenerating the strong resin flows into the bottom of the column via the pipe 9, valve 27 and lower collector 4, and passes through the ion exchange resin layer in an upward flow, and at the same time passes through the pipe 6, valve 23 and dispersion pipe 2. Treated water or inert gas flows downward, and the regenerated waste liquid or regenerated waste liquid and inert gas that flow out pass through the intermediate collector 3 and are discharged from the valve 24 and pipe 11 to regenerate the strong resin 14. The regenerant solution flow rate in this fifth step is 4 to 10/hr, and the drug passing time is 20/hr.
It is best to do this in about 4 minutes. Following the regeneration process in which the ion exchange resin resin whose function has been reduced is carried out in accordance with the procedure described above, an extrusion process and a water washing process are performed, but these processes are carried out using treated water. After performing the same operation procedure as in the conventional method, the rapid water process is started again.

As the regenerating agent used in the present invention, conventionally used mineral acids such as hydrochloric acid and sulfuric acid, or alkalis such as sodium hydroxide and potassium hydroxide are used, but the concentration thereof is not particularly limited. .

As explained in detail above, the present invention prevents the accumulation of suspended matter in the ion exchange resin layer in a conventional multilayer countercurrent regeneration ion exchange tower, and also prevents the mixing of weak resin and strong resin. Therefore, a certain amount of treated water can be stably obtained.

Next, the present invention will be explained with reference to Examples and Comparative Examples.

Example In a multi-layer co-flow regenerating ion exchange tower as shown in Figure 1, pure water was produced under the following conditions such as equipment dimensions, resin used, regenerant used, water composition to be treated, water flow conditions, etc. I did it.

'11 Equipment size intestinal ion exchange tower 160 units? x 450 shipboard decarbonation tower 95 yards x 450 yards anion exchange tower 160 yards x 400 yards Intestinal ion exchange resin Diaion SKI122700 Soge Weakly basic anion exchange resin Diaion WA302200 Soge Strongly basic anion exchange resin Diaion SAIOA2200 Soge (Diaion is a registered trademark of Mitsubishi Chemical Industries, Ltd.

) (3) Regenerating agent used b) Cation exchange resin .

) Anion exchange resin (4) Composition of water to be treated a) Cation b) Anion c) Lighting temperature 3 degrees '5} Water flow conditions Water flow rate 45/hr, liquid flow rate 22.5'hr Water flow end point is In the cation exchange tower, the electrical conductivity exceeded 5 peaks of S/G, and in the anion exchange tower, 0.1 ppm of silica (calculated as Si02) leaked.

Regeneration of each ion exchange preparative tower after completion of water flow was performed as follows.

First, in the intestinal ion exchange tower, 1.0% hydrochloric acid was passed through the bottom of the tower at a flow rate of 15 m/hr to make the ion exchange resin flow.
The solution was passed in an upward flow for 10 minutes, and the regenerated waste liquid was discharged from the upper part of the column to carry out the first step.

Next, in the second step, the treated water was passed through at a flow rate of 15'hr.
was introduced for 3 minutes with an upward flow of . Thereafter, the flow of treated water was stopped, and the third step was carried out for 5 minutes. During the water flow process in the first, second, and third steps, the suspended solids that are brought into the tower together with the water to be treated and captured in the ion exchange resin layer are discharged from the tower together with the regenerated waste liquid, and are weakened. The acidic cation exchange resin was completely stratified in the upper part, and the strongly acidic intestinal ion exchange resin was completely stratified in the lower part. After the third step, a fourth step was carried out in which treated water was introduced from the upper part of the tower and the recycled waste liquid remaining in the tower was discharged. In this step, treated water was passed through the upper part of the column at a flow rate of 5 hours for 30 minutes, and the recycled waste liquid was discharged from an intermediate collector.

Next, in the fifth step, 3% hydrochloric acid is introduced in an upward flow from the lower part of the column at a flow rate of 5/hr, and at the same time, the treated water is passed from the upper part of the column at a flow rate of 2/hr, and is then discharged. The recycled waste liquid was discharged from an intermediate collector.

This step was carried out for 15 minutes. As an extrusion step following the above-mentioned regeneration step, the treated water was pumped from the bottom of the column for 15 minutes.
At the same time, treated water was introduced from the tower at a rate of 2 m/hr to push out the regenerant liquid remaining in the tower.

After the extrusion process, as a water washing process, water to be treated is passed from the top of the tower in a downward flow of 45/hr for 10 minutes to wash the ion exchange resin, and the washing waste water is discharged from the bottom of the tower and then passed through again. Entered the water process.

On the other hand, the anion exchange tower was also regenerated using the same process as the cation exchange tower.

The first step was carried out by passing 2% caustic soda in an upward flow for 18 minutes at a flow rate of 5 hours. In the subsequent second step, treated water was introduced in an upward flow for 6 minutes at a flow rate of 5'hr.
The third step was performed for 10 minutes. In the fourth step, treated water was introduced from the upper part of the tower at a rapid water flow rate of 5/hr for 18 minutes, and the regenerated waste liquid was discharged. In the next fifth step, 1% caustic soda is introduced from the bottom of the tower in an upward flow at a flow rate of 5/hr, and at the same time, treated water is introduced from the top of the tower at a flow rate of 2/hr. I did it for a minute.

The extrusion step and water washing step following the regeneration step were performed under the same operating conditions as in the case of the intestinal ion exchange tower, and then the water passing step was started.

Purified water was produced by repeating the steps of water passage, regeneration, extrusion, washing, and water under the conditions described above, and when this was turned over in 6 subways, the amount of purified water was 690.

Comparative example For comparison, pure water was produced using a conventional method.

The experimental conditions were exactly the same as in the examples. The regeneration process after the water passage process was performed as follows. First, in the enteric ion exchange tower, 1% hydrochloric acid was passed from the top of the tower at a flow rate of 5/hr for 30 minutes, and then treated water was flowed downward at the same flow rate for 3 phr to remove the weakly acidic cation exchange resin at the top. At the same time, 2% hydrochloric acid was passed from the bottom of the tower at a flow rate of 5/hr for a few minutes, and then treated water was flowed upward at the same flow rate for 35 minutes to regenerate the strongly acidic intestinal ion exchange resin at the bottom. The recycled waste liquid flowing out was discharged from the intermediate collector. After the above-mentioned regeneration process, the water to be treated was passed from the upper part of the tower in a downward flow of 45/hr for 10 minutes to wash the ionic resin, and then the water passing process was started again. On the other hand, in the anion exchange tower, 2% caustic soda was passed from the top of the tower at a flow rate of 5 w/hr for 2 minutes, and then the treated water was flowed downward at the same flow rate for 30 minutes. The ion exchange resin is regenerated and at the same time 1. Flow rate of foldable soda is 5 m/hr.
for 35 minutes, and then the treated water was flowed upward at the same flow rate for 15 minutes to regenerate the strongly basic anion exchange resin at the bottom.

The recycled waste liquid flowing out was discharged from the intermediate collector. After the regeneration process as described above, the operating procedure was the same as that for cation exchange≠trout tower. Pure water was produced repeatedly under the above conditions, and the amount of pure water probed for the 20th time was 950, and the amount of pure water probed for the 60th time was 650, and the amount of pure water probed decreased.

As shown in the Examples and Comparative Examples above, according to the regeneration method according to the present invention, stable treated water can be obtained without reducing the depth of the treated water.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view of a co-flow regenerating ion exchange column of the same bed type in which the method of the present invention is carried out. In the figure, 1 is an ion exchange column, 2 is a dispersion tube, 3 is an intermediate collector, 4 is a lower collector, 13 is a weak resin, and 14 is a strong resin. Also, 5, 6, 7, 8, 9, 10, and 11 indicate tubes,
21, 22, 23, 24, 25, 26 and 27 indicate valves. younger brother diagram

Claims (1)

[Claims] 1. In a multilayer ion exchange tower in which a weak electrolyte ion exchange resin is layered on the top and a strong electrolyte ion exchange resin is layered on the bottom, the water to be treated is passed through the weak electrolyte ion exchange resin in the order of the strong electrolyte ion exchange resin. The treated water is obtained by
When regenerating the ion exchange resin when the ion exchange function of the ion exchange resin has decreased, the amount of regenerating agent liquid required to regenerate the weak electrolyte ion exchange resin is strongly applied at a flow rate that allows the ion exchange resin to flow. A first step of passing the drug from the lower part of the electrolyte ion exchange resin to the upper part of the weak electrolyte ion exchange resin; a second step of flowing the treated water from the lower part of the strong electrolyte ion exchange resin at the same flow rate as in the first step; A third step of stopping the inflow of treated water to settle the ion exchange resin, a fourth step of discharging the recycled waste liquid remaining in the tower from near the boundary between the strong electrolyte ion exchange resin and the weak electrolyte ion exchange resin, and then Regeneration waste liquid is passed through the lower part of the strong electrolyte ion exchange resin with the amount of regenerant solution required for regenerating the strong electrolyte ion exchange resin, and the above-mentioned treated water or inert gas is flowed out from the upper part of the weak electrolyte ion exchange resin. Alternatively, a method for regenerating a multi-layer ion exchange tower, comprising a fifth step in which the regenerated waste liquid and inert gas are discharged from near the boundary between a strong electrolyte ion exchange resin and a weak electrolyte ion exchange resin. .