JPH0516314B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pure water or ultrapure water production apparatus, and particularly to a condensate desalination apparatus for condensate treatment in thermal power plants and nuclear power plants.

[Conventional technology]

A mixed resin layer of two types of ion exchange resins, particularly a strongly acidic cation exchange resin (hereinafter referred to as SAR) and a strong basic anion exchange resin (hereinafter referred to as SBR), is used in polishers and ultrapure water production equipment. Indispensable for condensate desalination equipment in thermal and nuclear power plants. Conventionally, the most stringent water quality requirements for condensate treatment in PWR nuclear power plants are as follows.

Na゜ concentration 0.02ppb or less Cl ^- concentration 0.05ppb or less The lower the concentration of these ions, the better.

The amount of these ions leaking from the mixed resin layer depends on the inlet water quality conditions and the operating conditions of the mixed resin layer (LV, etc.)
Except for , it is controlled by the proportion of salt type resin in the mixed resin layer. Namely, R-Cl (chlorine type anion resin), R-Na (sodium type cation resin)
The higher the proportion of Na ^{+ and} Cl -, the greater the leakage of Na + and Cl ^- . The main reasons for the formation of R-Na and R-Cl are as follows, excluding Na° and Cl ^- derived from raw water.

R-Na: Separation and transfer of SAR and SBR is incomplete and SBR
SAR mixed into the layer is generated when it comes into contact with NaOH, which is an SBR regenerant.

R-Cl: (1) Produced by impurities (NaCl) in the regenerant NaOH. (2) Similar to R-Na, SBR remaining in the SAR layer due to incomplete separation is SAR
It is produced when it comes into contact with HCl, which is a regenerating agent.

Various methods have been studied to reduce R-Na production.
Typically, this problem has already been solved by Patent No. 1027750. The main cause of R-Cl formation (1) has become less of a problem due to improved quality of NaOH. Regarding (2), with conventional technology, separation and transfer is incomplete and SAR
About 1 to 2% of the total SBR remains in the layer, and this is accumulated each time it is regenerated, so that in an equilibrium state, the R-Cl of the mixed resin layer is about 20% of the total SBR.

A conventional resin separation and transfer method will be explained with reference to FIG. After the resin is separated into two layers, SAR layer 1 and SBR layer 2, by backwashing, sluging water is introduced from the sluicing water pipe 3 at the bottom of the tower at a LV of about 2.5 m/hour to slightly fluidize SAR layer 1. Meanwhile, pressurized water is introduced from the pressurized water pipe 4 at the top of the tower, or pressurized air is introduced from the pressurized air pipe 6 to transfer the SBR to the anion regeneration tower.
Although the opening of the transfer pipe 8 during transfer is provided on the central axis of the tower in FIG. 8, it may be provided in the wall of the tower, or a gutter may be used in some cases. Further, the height of the opening is usually set to be slightly below the interface between the two resin layers.

When carrying out such a transfer, it is inevitable that SBR 2' remains in the range of several mm to 20-odd mm, as shown in FIG.

The reason for this is that the closer the SBR is to the tower wall, the longer it takes to reach the opening of the transfer pipe 8, during which time the resin near the opening is transferred, and the resin surface becomes flat due to sluicing water from the lower part of the tower, causing the opening of the SBR to become flat. This is because a certain distance is created between the part and the surface of the resin layer, and SBR is no longer transferred.

This phenomenon occurs in the same way even if the amount of sluicing water is increased, the expansion rate of the SAR layer is increased, or the height and shape of the opening are changed, complete separation and transfer of SBR cannot be achieved.

These remaining SBRs come into contact with HCl, which is a SAR regenerating agent, and R-Cl is generated.

[Problem that the invention seeks to solve]

The present invention solves the problem (2) above,
Minimize the SBR remaining during separation and transfer as much as possible,
The purpose is to improve the quality of the treated water during ion exchange.

[Means for solving problems]

In the present invention, in a tower filled with two types of ion exchange resins with different specific gravity, after the ion exchange resin is separated into two layers by backwashing, pressurized water or pressurized air is introduced from the upper part of the tower, and sluicing water is introduced from the lower part of the tower. In this method, most of the ion exchange resin with low specific gravity is transferred through a resin transfer pipe, and after the transfer, a small amount of ion exchange resin with low specific gravity remaining on the ion exchange resin layer with high specific gravity is further separated and transferred. (A) A transfer sluging pipe is placed below the interface between the two types of ion exchange resin layers across the center of the column, with the transfer sluging pipe crisscrossing the center of the transfer pipe on both sides. (B) While keeping the ion exchange resin with a high specific gravity in a fluid state, the transfer water is blown upward from the transfer sluicing pipe to transfer the ion exchange resin with a low specific gravity. A method for separating and transferring an ion exchange resin, characterized in that the resin is transferred to the opening of the resin transfer tube, or is transferred through the resin transfer tube after being transferred, and the problems with the conventional separation and transfer method are as follows: In order to solve this problem, we conducted extensive research using a practical-scale column with a large diameter, and as a result, we arrived at the present invention.

Hereinafter, the present invention will be explained in detail based on the drawings.

The present invention uses SAR with high specific gravity as shown in Figure 1.
In order to separate and transfer the SBR 2' with a low specific gravity remaining on the layer 1, a sluging pipe 7 for transfer that crosses the center of the column is provided at the lower part of the interface;
Resin transfer pipes 8, 8 having openings 8', 8'' are provided therein in a criss-crossing positional relationship, respectively.
By introducing low-flow backwash water from the lower part of the tower through the pipe 3 to bring the SAR into a fluid state, water is also blown upward from the transfer sluging pipe 7, so that the diagonal line in Fig. 7 is achieved. As shown in , SBR is transferred to the area where SBR has gathered around the openings 8' and 8'' of the resin transfer pipes 8 and 8. 5 is a backwash water discharge pipe. That is, the present invention SAR
The SBR is brought into a fluid state and water is blown upward from the center of the SAR layer to collect SBR around the openings 8', 8'' of the transfer pipes 8, 8.

The most important aspect of the present invention is the flow rate of water blown upward from the transfer sluging pipe. If this flow rate is too high, the flow of the SBR resin layer 2' will flow toward the openings 8' and 8'', but it will hit the tower wall and become a reverse flow. When this reverse flow occurs, the SBR that has once collected will As a result of experiments, it was found that this flow velocity should be as small as LV 0.5 to 2 m/hour.

Furthermore, it has been found that there is almost no risk of reverse flow occurring when the water is blown out from the transfer sluging pipe 7 in a continuous manner. If the water is blown out repeatedly for 5 to 30 seconds and paused for 15 to 60 seconds, the resin surface directly above the transfer sluging pipe 7 will rise slightly as shown in FIG. 6. In order to do this completely, the SBR2' becomes wavy and moves toward the opening, but the best condition is for this wave to almost disappear near the openings 8' and 8'', so do it like this. As shown in FIG.
When the resin 2' gathers at the resin transfer pipe openings 8', 8'' as shown in FIG. 7, the resin transfer pipe valve 9 of the resin transfer pipes 8, 8 It is possible to open and transport concentrated SBR at any time. It is preferable to continue blowing out water from the transfer sluging pipe 7 during transfer.

In other words, the present invention includes the following steps: 1. Bringing the resin layer SAR1, which has a high specific gravity, into a fluidized state by backwashing water; 2. Blowing water further upward from the transfer sluging pipe 7 provided in the middle of the resin layer; and 3. Bringing the resin SBR2, which has a low specific gravity, into a fluid state. As shown in Fig. 7, the liquid is collected at the openings 8' and 8'' of the transfer pipes 8 and 8, and then transferred.This is a combination of each of the steps 1) to 4) above.These series of steps are performed once. Most of the SBR will be transferred even if the resin transfer pipes 8, 8, 8' and 8'' are transferred, but in order to ensure and complete transfer, it is preferable to repeat the above process several times. As shown, it is installed at a position perpendicular to the center of the transfer sluging pipe. If this shifts, the opening will shift from the center of the concentrated SBR, making complete transfer difficult. The height of the opening is
It is sufficient to determine the amount of SAR remaining after transfer while considering the backwash development rate of the SAR layer 1 so that it is quantitative. Normally, when the backwash development rate is increased, SAR
Since errors are likely to occur in the quantitative nature of
It is preferable to keep the conditions within the range of LV3 to 5m/hour. The shape of the opening is shown in Figure 7.
A curved tube shape may be used depending on the concentration state of SBR.

The position of the transfer sluging pipe 7 may be 300 to 600 mm below the resin boundary surface; if this distance is too small, the water jets will be in a bumping state, and if this distance is too large, the water jets will diffuse and the effect will be reduced. The number of the transfer sluging pipes 7 may be one as shown in FIG. 2, or two as shown in FIG. 3.
In consideration of uniform dispersion of water, if the diameter of the column is large, it is preferable to provide two columns as shown in FIG. In any case, it is sufficient as long as it can create a flow of SBR toward the two openings.

Hereinafter, the present invention will be explained in detail for each step using a separation column of a condensate desalination apparatus as an example.

FIG. 4 is an explanatory diagram showing an example of an embodiment of the present invention.

Components with the same names are given the same reference numerals as in FIGS. 1 and 8.

After the mixed resin transferred from the demineralization tower (not shown) is thoroughly backwashed and separated in the separation tower 10 by opening the backwash water inlet valve 11 and the backwash drain valve 12 at a rate of LV8 to 10 m/hour. Valves 11 and 12 are closed. After calming down, open the sluicing water valve 13 and LV0.7~
Slewing water is introduced at a rate of 1.5 m/hour, and the pressurized water valve 16 at the top of the tower and the valves 9 and 9 of the resin transfer pipes 8 and 8
is opened and most of the SBR2 is transferred to an anion regeneration tower (not shown).

When the sluging water flow rate is reduced to LV 0.7 to 1.5 m/hour, the SAR layer virtually does not flow.
Only the SBR layer is slightly fluid. When such a transfer is performed, the resin surface is transferred from the center of the tower to the resin transfer pipe 8,
8, but if it were made uniform, the openings 8' and 8'' would be as shown in Figure 5.
It is located within the SAR layer.
When this flow rate is increased, the backwash expansion rate of the SAR layer increases accordingly, and the SAR layer is transferred to the anion regeneration tower.
SAR increases, and the distance l' between the opening and the layer surface decreases as shown in FIG. 5, which is not preferable for complete transfer of the remaining SBR2.

Next, the valves 9, 9, sluicing water valve 13, and pressurized water valve 16 were closed, and the backwash drain valve 12 and low flow rate backwash valve 14 were opened to bring the SAR layer into a fluid state at LV 3.5 to 4.5 m/hour. do. The residual SBR is then transferred by the method of the present invention. It is important to control the opening degree of the low-flow backwash valve 14 so that the SAR development rate is always constant, taking into consideration the water temperature, etc.

Next, the transfer sluicing water valve 15 is opened, and
Transfer sluging water is introduced from the transfer sluging pipe 7 at a LV of 0.5 to 2 m/hour and is blown out toward the top. Then, as shown in Fig. 6, the resin layer at the blown part rises, and the SBR as shown in Fig. 7 is formed.
A flow is formed and the SBR gradually gathers at the opening. This step may take about 0.5 to 2 minutes.

Then, valve 12 is closed, valves 9, 9, and 16 are opened,
This will transport the SBR that has gathered at the opening. The sluging water for transfer may be continuously blown out from the sluging water pipe 7, but if the flow velocity is high, it may collide with the tower wall and the reverse flow may make it difficult for SBR to collect. It is preferable to do so.

If the air is blown intermittently for 5 to 30 seconds with a pause of 15 to 60 seconds, the state shown in FIG. 7 can be easily achieved even if the flow rate is increased to LV1.5 to 2.5 m/hour.

By repeating such transfer several times, the residual SBR is completely transferred to the anion regeneration tower.

The repeated steps are summarized as follows.

Valve in open state Time backwash separation 11, 12 3 to 5 minutes transfer (1) (SBR gathering process) 12, 14, 15 1 to 2 minutes transfer (2) (Transfer) 16, 9, 14, 15 1 to 2 minutes In addition, in this embodiment, a method was shown in which the material was moved to the opening and then transferred from the transfer pipe.
It is also possible to transfer while moving.

In order to clarify the effects of the present invention, comparative examples and examples will be described below.

Comparative Example 1 (Conventional method) As SAR in a separation column with an inner diameter of 1800φ and a height of 5000mm
Dowex TG650C(R) 4500l, as SBR
It was filled with 2000 liters of Dowex TG550A (registered trademark) mixed resin, and backwash water was introduced from the bottom of the column at a LV of 10 m/hour to separate the resin into two layers.

Next, the sluicing water from the bottom of the tower is
The water was introduced at a LV of 2.5 m/hour, and at the same time pressurized water was introduced from the top of the tower at a LV of 4 m/hour. The resin transfer pipe had one opening on the central axis of the tower, and had a diameter of 75φ.
The opening was located 100 mm below the resin interface.

The SBR remaining after transfer was 0.5-0.6% of the total SBR.

Investigation method for residual SBR After transfer, backwashing was performed for 40 minutes at a LV of 10 m/hour, all the SBR that had accumulated on the surface was scraped off, and the volume was measured.

Example 1 A tower of the same size as Comparative Example 1 was used. After separating the resin into two layers in the same manner as in Comparative Example 1, sluicing water from the bottom of the column was introduced at a LV of 1.2 m/hour and pressurized water from the top of the column was introduced at a rate of LV 4 m/hour to transfer most of the SBR. The remaining SBR was transferred.

There were two resin transfer tube openings as shown in FIG. 4, and the other conditions were the same as in Comparative Example 1.

<Transfer of residual SBR> Low-flow backwash water was introduced at LV4m/hour to bring SAR into a fluid state. Furthermore, water was continuously blown out for 1 minute at a LV of 1 m/hour from a sluicing water pipe (one) for transfer provided 450 mm below the resin separation surface across the center of the column, and then transferred for 1 minute. Then
After performing backwash separation for 3 minutes at LV5 m/hr, residual SBR was transferred in the same manner as above. These steps were repeated three times. After repeating the above transfer only 10 times
I went for a minute.

The residual SBR was 0.02-0.035% of the total SBR.

Example 2 The residual SBR was transferred in the same manner as in Example 1, except that the sluicing water for transfer was blown out intermittently for 15 seconds and paused for 15 seconds.
All residual SBR was 0.015-0.025% of SBR.

Example 3 Using the same method as in Example 1, the filling resin had the following configuration.

SAR: Dowex HGR−W2 SBR: Dowex TG 550A The residual SBR was 0.02 to 0.035 of the total SBR.

〔Effect of the invention〕

As mentioned above, according to the method of the present invention, residual
SBR can be reduced to 1/15 to 1/40 of conventional methods. Therefore, the amount of R-Cl (chlorine type anion resin) produced can be reduced and the quality of treated water can be greatly improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic vertical view of an example of an ion exchange resin separation column for explaining the method of the present invention, and Fig.
A cross-sectional view taken along the line A-A' in the figure.
Figure 4 is a schematic cross-sectional view of the ion exchange resin separation column used in the present invention to explain the present invention in more detail, Figure 5 is a resin transfer Figures 6 and 7 are diagrams for explaining the positions of the openings of the tubes; Figures 6 and 7 are diagrams for explaining the flow (moving state) of the resin when the ion exchange resin with a light specific gravity is further separated; The figure is a schematic vertical cross-sectional view of an example of a resin separation column to explain the conventional separation method of ion exchange resin, and Figure 9 shows the state of a small amount of resin with a light specific gravity remaining on the ion exchange resin layer with a heavy specific gravity. FIG. 1... SAR layer, 2... SBR layer, 3... Sluging water pipe, 4... Pressurized water pipe, 5... Backwash drain pipe, 6... Pressurized air pipe, 7... Sluging pipe for resin transfer, 8... Resin transfer pipe, 9 ...Resin transfer valve, 10...Ion exchange resin separation tower, 11...Backwash water inflow valve, 12...Backwash water discharge valve, 13...Sluicing water valve, 16...Pressurized water valve, 14...Low flow rate backwash valve, 15 ...Transfer sluicing valve.

Claims (1)

[Claims] 1. In a tower filled with two types of ion exchange resins with different specific gravities, after the ion exchange resins are separated into two layers by backwashing, pressurized water or pressurized air is supplied from the upper part of the tower and from the lower part of the tower. Sluicing water is introduced to transfer most of the ion exchange resin with low specific gravity through the resin transfer pipe, and after the transfer, a small amount of ion exchange resin with low specific gravity remaining on the ion exchange resin layer with high specific gravity is removed. Furthermore, in the method of separating and transferring, (A) a positional relationship in which a transfer sluging pipe is placed below the interface between the two types of ion exchange resin layers across the center of the column and intersects with the transfer sluging pipe in a criss-cross manner; (B) While maintaining the ion exchange resin having a large specific gravity in a fluid state, transfer water is blown upward from the transfer sluging pipe. A method for separating and transferring an ion exchange resin, characterized in that an ion exchange resin having a small specific gravity is transferred to the opening of the resin transfer tube, or after being transferred, the resin is transferred by the resin transfer tube. 2. The method according to claim 1, wherein the transfer water is intermittently blown upward from the transfer sluging pipe.