JPS6058240A - Backwashing separation of resin mixture - Google Patents

Abstract

PURPOSE:To perform the perfect separation of resin mixture, in the backwashing separation of the resin mixture consisting of anion and cation exchange resins, by forming a separated and expanded layer while taking out the greater part of the upper layer resin, and thereafter, again forming a separated and expanded layer. CONSTITUTION:Backwashing water 3 is flowed into an anion exchange tower 2 packed with a resin mixture 1 from the lower part thereof as is conventional to separate the resin mixture 1 and anion and cation resins 6', 7' in an expanded state are formed. As a result, the resin mixture 1' remains in the peripheral edge part 5 of a support plate 4. Herein, the inflow of backwashing water 3 is stopped and the resins 6', 7' are precipitated and conditioned (or not) and the greater part of the resin 6 is taken out of the tower from an outtake pipe 10 preliminarily provided in the vicinity of the separation surface 9 between both resins. In the next step, backwashing water 3 is again flowed into the tower to reopen backwashing separation or, when the resin 6' is taken out, the inflow of backwashing water is succeeded. By this method, the resin 1' separated into expanded resins 6', 7' to form upper and lower layers.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in backwashing and separating a mixed resin of an anion exchange resin and a cation exchange resin.

Mixed-bed ion exchange equipment that uses a mixed resin of anion exchange resin and cation exchange resin has traditionally been used in pure water production equipment that uses industrial water as raw water or condensate desalination equipment in thermal power plants, nuclear power plants, etc. It is being This mixed bed type ion exchange equipment treats the water to be treated using a mixed resin of an anion exchange resin and a cation exchange resin.・In regenerating both ion exchange resins after treatment・The mixed resin is used as an anion exchange resin. It is necessary to separate into a cation exchange resin. Conventional separation methods include separation using a specific gravity liquid such as aqueous sodium hydroxide solution in rare cases. Normally, backwashing with water flow as shown below is used. Separation is taking place. That is, first, from the lower part of the ion exchange tower filled with the mixed resin, flow rate such that the mixed resin expands by about 100%, normal LV (@speed, same below) 7 to 12.
1')] is introduced to cause the mixed resin to expand and flow. When the mixed resin is allowed to expand and flow in this way, a difference occurs in the sedimentation speed of both ion exchange resins in rising flowing water, with the anion exchange resin having a lower specific gravity gathering at the top and the cation exchange resin having a higher specific gravity gathering at the bottom, resulting in an expanded state. Two layers of anion exchange resin and cation exchange resin are formed. After such two layers are formed, when the inflow of backwash water is stopped, the expanded anion exchange resin and cation exchange resin settle in the water.The lower layer is the cation exchange resin layer, and the upper layer is the anion exchange resin layer. A separation layer can be formed.

After performing such backwash separation, leave the two layers formed, or take out the anion exchange resin in the upper layer into a separate bath, regenerate the cation exchange resin with acid and the anion exchange resin with alkali, and wash with water. After that, recycled both ion exchange resins are mixed and the water is passed through again.

By the way, when separating mixed resins in mixed bed ion exchange equipment such as pure water production equipment for the electronic industry that requires high purity treated water or condensate desalination equipment for thermal power plants and nuclear power plants, the above-mentioned However, in the mixed bed type ion exchange equipment, the problem of insufficient increase in purity frequently occurred.As a result of various studies on the causes of this problem, in the conventional backwash separation method explained below, It was found that incomplete separation was a major factor.

That is, in the conventional backwash separation method, as shown in Fig. 1, backwash water 3 of LV 7 to 12 m/H is flowed in from the bottom of the ion exchange tower 2 filled with the mixed resin as described above. The mixed resin is expanded and flowed to level L, which is approximately 100% of the resin layer height. Due to this backwashing, most of the mixed resin expands and flows as shown in Figure 2, and the anion exchange resin is in an expanded state. 6' and cation exchange resin 7'
However, the mixed resin 1' existing on the peripheral edge 6 of the support plate 4 expands and flows and remains as it is. The anion exchange resin in this mixed resin 1' may amount to 3 to 5 inches of the total amount of anion exchange resin.

The reason why the mixed resin 1' existing on the peripheral edge 5 of the support plate 40 remains as it is is due to the fact that water does not flow easily to that part. If it remains in the trenches, it will cause problems in the subsequent regeneration, which will make it difficult to increase the purity of the treated water.

a To regenerate, when hydrochloric acid 8 is passed through the mixed resin 1'
The anion exchange resin inside is C1 type. As shown in FIG. 3, even when the upper layer anion exchange resin 6 is not taken out and the separated anion exchange resin zero 6 and cation exchange resin are partially regenerated, the anion exchange resin in the mixed resin 1' is The same goes for the 01 type.

In this way, the presence of C1 type anion exchange resin after regeneration will result in a poor increase in the purity of the treated water.Especially in the condensate desalination equipment of pwR type nuclear power plants, it is necessary to limit the leakage of 01 ions in the treated water. Therefore, the amount of C1 type anion exchange resin mixed in after regeneration must be reduced as much as possible.

The purpose of the present invention is to solve the drawbacks of the conventional backwash separation method as described above, and to provide a backwash separation method that does not leave mixed resin on the peripheral edge of the support plate. When backwashing water is introduced from the bottom of the ion exchange tower filled with a mixed cation exchange resin and separated into an anion exchange resin and a cation exchange resin - From the bottom of the ion exchange tower filled with the mixed resin Backwash water is flowed in to form a separated expanded layer of anion exchange resin and cation exchange resin.Then, most of the anion exchange resin in the upper layer is taken out to the outside of the ion exchange tower without settling or settling.Subsequently, ion exchange is carried out. The present invention relates to a method for backwashing and separating a mixed resin, which is characterized in that backwashing water is introduced from the lower part of a column to form a separated expanded layer of residual anion exchange resin and cation exchange resin and settle.

The present invention will be explained in detail below.

The disadvantage of the conventional backwash separation method is that the mixed resin remains on the periphery of the support plate.The reason for this is that the water flow around the periphery of the support plate is slow, so the mixed resin in that area does not expand and flow. It depends.

The present inventors investigated various ways to prevent the mixed resin from remaining on the periphery of the support plate. After performing normal backwash separation, most of the anion exchange resin formed in the upper layer was taken out to a separate bath and reused. It was discovered that when backwash water flows in, the mixed resin at the peripheral edge of the support plate becomes fluid, and as a result, when the backwash expansion layer is settled, the mixed resin no longer remains at the peripheral edge of the support plate.

It should be noted that by carrying out such an operation, it is not clear at present why the mixed resin does not remain, but most of the anion exchange resin is probably taken out of the column, so the entire inside of the ion exchange column is removed. This is thought to be because the amount of resin in the ion exchange column decreases, making it easier for all the ion exchange resin in the ion exchange column to flow.

In any case, according to the present invention, the mixed resin at the peripheral edge of the support plate can be made to flow, and as a result, the drawbacks of conventional backwash separation can be reliably solved.

Below, the backwash separation method of the present invention will be explained step by step with reference to the drawings.

First, in the present invention, as shown in FIG.
Backwash water 3 with a flow rate of LV'7 to 12 mA1, which is such that the resin bed height expands approximately 100% of the packed resin bed height, is introduced from the lower part of the ion exchange tower 2 filled with the mixed resin. An anion exchange resin 6' and a cation exchange resin 6' are formed in a separated and expanded state. Note that the inflow time of the backwash water 3 may be the time required for the two ion exchange resins to be approximately separated; usually, around 15 minutes is sufficient.

Since the operation up to this point is the same as the conventional backwash separation, the mixed resin 1' remains on the peripheral edge 5 of the support plate 40 as shown in FIG.

Next, in the present invention, the inflow of backwash water 3 is stopped, and both ion exchange resins in an expanded state are settled.As shown in FIG. Most of the anion exchange resin 6 in the upper layer is taken out of the column from the anion exchange resin take-out pipe 10.

When taking out the upper layer of anion exchange resin 60, in addition to taking it out after settling as described above, you can also take it out when both ion exchange resins are in an expanded state as shown in Figure 4. However, in this case, it goes without saying that the anion exchange resin outlet pipe qo is attached above the separation interface between both ion exchange resins in an expanded state.

・When the anion exchange resin is taken out under the expanded condition, the backwash water 3 is continued to flow in and the backwash separation is continued. .

Due to such backwash separation, the mixed resin existing at the peripheral edge of the support plate 40 flows, and as shown in FIG. The exchange resin rises due to the difference in specific gravity, forming an anion exchange resin 6' that expands and flows, and forms a cation exchange resin 7' that expands and flows below it. Note that the flow rate of the backwash water 3 may be the same LV'7 to 12 m/H as the backwash water 3 before the anion exchange resin is taken out of the tower, but since it is after the anion exchange resin is taken out of the tower.・The height of the expanded resin layer is 100 cm or more with respect to the height of the filled resin layer, for example, LV12 m/H or more. Preferred for fluidization of mixed resins.

)? If Mf+ 1Ti71 Itr21λto^
It is more preferable to flow the compressed air 11 from the lower part of the ion exchange tower 2 at the same time as the flow of the ion exchange column 2 returns to work, in order to fluidize the mixed resin present at the peripheral edge of the support plate.

The inflow time of the compressed air 11 is sufficiently effective, for example, in a short period of about 3 minutes, and the air amount is 2N rr?
It may be around /min/+n'.

After most of the anion exchange resin has been taken out, when the backwash water 3 is allowed to flow in for about 20 minutes, the anion exchange resin in the mixed resin that was present at the periphery of the support plate 4 almost completely rises due to the difference in specific gravity. Anion exchange resin 6' and cation exchange resin 1' are formed which expand and flow. When such a state occurs, the inflow of backwash water 3 is stopped and the expanded resin layer is settled. After settling, the anion exchange resin in the upper layer is taken out through the anion exchange resin take-out pipe 10.The cation exchange resin remaining in the ion exchange tower 2 is regenerated with acid by a conventional method.The entire anion exchange resin taken out from the ion exchange tower 2 is The resin is regenerated with alkali in a separate column using conventional methods.

As explained above, if the backwash separation of the present invention is performed, the mixed resin will not remain on the periphery of the support plate, and therefore the amount of C1 anion exchange resin produced during regeneration of the cation exchange resin will be significantly reduced. It is possible to effectively solve the drawback of CI ions leaking into the treated water, which occurs in conventional mixed bed ion exchange equipment.

Examples will be described below to clarify the effects of the present invention.

Example-1 Inner diameter 2+00OR11l Straight section height 6. Into the ion exchange column of OOOG, add 6.2801 of strong acidic cation exchange resin Amberlite (registered trademark) 2000 and 3*140g of strong basic anion exchange resin Amberlite (registered trademark) 1. RA-9
00 mixed resin was filled, and the cation exchange resin and anion exchange resin were separated using the backwash separation method of the present invention and the conventional backwash separation method described below. -(1) Conventional method: Backwash water of LViOm/H from the bottom of the ion exchange tower at 30%
After the cation exchange resin and anion exchange resin were backwashed and separated by flowing for a minute, the backwash water was stopped flowing and settled.

(2) Method of the present invention After backwashing water of Lv10ITI/H flows in from the lower part of the ion exchange tower for 10 minutes to backwash and separate the cation exchange resin and anion exchange resin, the inflow of the backwash water is stopped and the water settles. After about 98% of the anion exchange resin in the upper layer is transferred to another tower, the LVIOm/
After flowing H backwash water for 20 minutes, the flow of backwash water was stopped and settling was performed.

When backwash separation was performed using the conventional method and the method of the present invention as described above, and the anion exchange resin in the cation exchange resin was measured, the following results were obtained.

First, in the conventional method, only the separated upper anion exchange resin is carefully taken out to a separate column, and then compressed air is introduced from the lower part of the ion exchange column to 'fl=--μ.
About 1 g of Al sample resin was collected and separated into anion exchange resin and cation exchange resin based on the difference in specific gravity of each using saturated saline.・Cation exchange resin The anion exchange resin inside was 2.5 liters per volume.

This amount of anion exchange resin corresponds to 5% of the total anion exchange resin.

In the method of the present invention, only the remaining upper anion exchange resin is carefully taken out to a separate column, then compressed air is introduced from the bottom of the ion exchange column to uniformly mix the cation exchange resin, and 1X sample resin is collected. When the anion exchange resin and cation exchange resin were separated using a saturated saline solution based on the difference in their specific gravity, the anion exchange resin in the cation exchange resin was as small as 0.10% by volume.

The amount of this anion exchange resin is 0.2 of the total anion exchange resin.
It's just a staff member.

That is, according to the method of the present invention, the amount of anion exchange resin remaining on the peripheral edge of the support plate is reduced to 1/25th of that of the conventional backwash separation method.
It was confirmed that the amount has decreased.

Example-2 Inner diameter 2+0001ToTl+Straight section height 6I00011
6,280 tons of strong acidic cation exchange resin Amberlite (registered trademark) 2000 and 3+1 were installed in the In ion exchange column.
40j strongly basic anion exchange resin Amberly) I
A mixed resin having an RA of -900 was filled, and the cation exchange resin and anion exchange resin were separated using the backwash separation method of the present invention and the conventional backwash separation method described below.

(1) Conventional method After backwashing water of LV 10ITL/H was flowed in from the bottom of the ion exchange tower for 30 minutes to backwash and separate the cation exchange resin and anion exchange resin, the backwash water was stopped flowing and settled. .

(2) Method of the present invention After backwashing water of LV 1oIv/H is introduced from the lower part of the ion exchange tower for minutes to backwash and separate the cation exchange resin and anion exchange resin, the inflow of backwash water is stopped and the water settles.・Next, after transferring about 98% of the anion exchange resin in the upper layer to a separate bath, ・1.5 kg, 4
At the same time, backwash water of Lvl, 0@/H was flowed in for 2 minutes. After flowing in from the bottom of the tank for 18 minutes, the inflow of backwash water was stopped and the water settled.

When backwash separation was performed using the conventional method and the method of the present invention as described above, and the anion exchange resin in the cation exchange resin was measured, the following results were obtained.

First, in the conventional method, only the separated upper anion exchange resin is carefully taken out into a separate bath, compressed air is introduced from the bottom of the ion exchange tower, the cation exchange resin layer is mixed uniformly, and about 11 sample resins are collected. When the anion exchange resin and cation exchange resin were separated using a saturated saline solution based on the difference in their specific gravity, the anion exchange resin in the cation exchange resin was 2.5% by volume.

This amount of anion exchange resin corresponds to 5 parts of the total anion exchange resin.

In the method of the present invention, after carefully taking out only the remaining upper anion exchange resin into a separate bath, compressed air is introduced from the bottom of the ion exchange tower, and the cation exchange resin layer is uniformly mixed to obtain about 11% of the sample resin. When the anion exchange resin and cation exchange resin were collected and separated using saturated saline based on the difference in their specific gravity, the anion exchange resin in the cation exchange resin was as small as 0.05% by volume.

The amount of this anion exchange resin is 0.1 of the total anion exchange resin.
It's just a chi.

That is, according to the method of the present invention, the amount of anion exchange resin remaining on the peripheral edge of the support plate is reduced to one-fiftieth of that of the conventional backwash separation method.
It was confirmed that the amount has decreased.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are conventional backwash separation methods. Figure 1 is an explanatory diagram of the state before backwash separation. Figure 2 is an explanatory diagram of the state during backwash separation. Figure 3 is backwash separation. FIG. 6 is a diagram illustrating the state after the anion exchange resin is transferred to a separate bath (not shown). Also, Figures 4, 5, and 6 are explanatory diagrams showing the separation state in the backwash separation method of the present invention. Figure 4 is an explanatory diagram of the backwash separation state before taking out the anion exchange resin. - Figures 5 and 6 are explanatory diagrams of the state after the anion exchange resin is taken out. 1. Mixed resin 20.・Ion exchange tower 30. , backwash water 400. Support plate 50.2 peripheral edge 69.・Anion exchange resin layer 78
．． , cation exchange resin rim 81.・Hydrochloric acid 9001 minutes
Separation surface 10. ,,Anion exchange resin outlet pipe n,,
, Compressed airFigure 1Figure 3Figure 4Figure 2Figure 3Figure 5Figure 6

Claims (1)

[Claims] When backwashing water is introduced from the bottom of the ion exchange column filled with a mixed resin of anion exchange resin and cation exchange resin to separate it into an anion exchange resin and a cation exchange resin, an ion exchange column filled with the mixed resin is used. Backwash water is introduced from the bottom of the tower to form a separated expanded layer of anion exchange resin and cation exchange resin.Then, most of the anion exchange resin in the upper layer is taken out to the outside of the ion exchange tower without settling or settling. A method for backwashing and separating a mixed resin, which method comprises subsequently introducing backwash water from the lower part of the ion exchange tower to form a separation expansion layer of the remaining anion exchange resin and cation exchange resin and settling it.