JP7215094B2 - Ion exchange resin regeneration device - Google Patents

Description

The present invention relates to an ion-exchange resin regeneration device for condensate demineralization equipment, and more particularly to an ion-exchange resin regeneration device for condensate demineralization equipment in thermal power plants, nuclear power plants, and the like.

Condensate desalination is usually performed by installing a cation exchange resin regeneration tower, an anion exchange resin regeneration tower and a resin storage tank for ion exchange resin regeneration, and chemical regeneration is performed with sulfuric acid and caustic soda (for example, Patent Document 1, 2).

The ion exchange regeneration device and regeneration method described in Patent Document 1 will be described with reference to FIGS. 5 and 6(a) to (c). This regeneration device includes a condensate demineralization tower 1, a cation exchange resin regeneration tower 3, an anion exchange resin regeneration tower 5, a resin storage tank 8, and pipes 2, 4, 6, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 11, 12, 13, 14, 14, 14, 14, 14, 15, 16, 18, 18, 18, 19, 19, 19, 19, 19, 19, 19, 19, 9 is an ion-exchange resin regeneration device in a condensate demineralization unit using an extra-tower regeneration method. The condensate demineralization tower 1 is filled with a mixture of cation exchange resin and anion exchange resin.

During normal operation, the passage of liquid through the pipes 2, 4, 6, 7, and 9 is stopped by closing the valves (not shown) provided in each pipe. Desalination is performed by passing condensate through the condensate demineralization tower 1 only through the pipes 1a and 1b. Regeneration of the ion-exchange resin by this regenerator is carried out through the following resin removal/separation process, backwashing regeneration process, and resin mixing/returning process.

<Resin removal/separation process>
(i) Stop the liquid flow through the pipes 1a and 1b and disconnect the condensate demineralization tower 1 from the main system.
(ii) Transfer the ion exchange resin in the condensate demineralization tower 1 to the cation exchange resin regeneration tower 3 through the pipe 2 . (Fig. 6(a))
(iii) As shown in FIG. 6(b), by passing backwash water through the cation exchange resin regeneration tower 3 in an upward flow, the ion exchange resins in the mixed state are separated from the anion exchange resin and the cation exchange resin by the difference in specific gravity. separated into two upper and lower layers.
(iv) As shown in FIG. 6( c ), the anion exchange resin is selectively withdrawn through the pipe 4 and transferred to the anion exchange resin regeneration tower 5 .

Incidentally, Patent Document 2 describes that after that, the resin is separated and transferred again as shown in FIGS. 6(d) to 6(f). That is, when the anion exchange resin is discharged and transported to the level of the anion exchange resin discharge port 4a, as shown in FIG. A mixed layer of resin and cation exchange resin remains.

Therefore, backwashing is performed by accelerating the LV of the backwash water and circulating it upward to push up the interface between the mixed layer and the cation exchange resin layer and promote further resin separation in the mixed layer (Fig. 6(d)). The backwash water upward flow rate is adjusted so that this interface is lowered to the vicinity of the anion exchange resin outlet 4a (FIG. 6(e)), and then the mixed resin of the anion exchange resin and the cation exchange resin constituting the mixed layer is treated with an anion It is transferred to the resin storage tank 8 via the replacement resin discharge port 4a, the pipe 4 and the pipe 7A (Fig. 6(f)). As a result, the residual amount of the anion exchange resin in the cation exchange resin in the cation exchange resin regeneration tower 3 is significantly reduced.

<Backwash regeneration process>
(v) In the cation exchange resin regeneration tower 3, while the ion exchange resin is immersed in water, air is blown from below (air scrubbing) to detach corrosion products (crud, etc.) adhering to the resin.
(vi) In the cation exchange resin regeneration tower 3 and the anion exchange resin regeneration tower 5, acid and alkali are respectively injected to regenerate the cation exchange resin and the anion exchange resin regeneration tower 5.

<Resin mixing/returning process>
(vii) After chemical regeneration is completed, the regenerated cation exchange resin and anion exchange resin are transferred to the resin storage tank 8 through the pipes 6 and 7, respectively.
(viii) washing and mixing operations in the resin reservoir 8;
(ix) The ion exchange resin in the resin storage tank 8 is returned to the condensate demineralization tower 1 through the pipe 9 in a mixed state.
(x) The flow of liquid through the pipe 9 is stopped, and the condensate demineralization tower 1 is put on standby as a standby tower.

As a result, the regeneration is completed, and the flow of condensate is resumed via the pipes 1a and 1b, and the desalting operation is resumed.

JP-A-55-051445 JP 2018-126687 A

In the conventional cation exchange resin regeneration tower, although not shown, a drainage pipe and a chemical injection pipe were arranged below the anion exchange resin discharge port 4a. The drainage pipe is a wedge wire or the like, and is a straight pipe that does not allow the resin to flow out but only water and fine iron clad to be discharged. The chemical injection pipe is a radial pipe provided with a small hole facing downward, and is installed below the resin discharge port 4a.

However, since the location where these pipes are installed is near the resin separation boundary surface in the backwashing separation of the mixed resin, the backwash flow hits the chemical injection pipe and causes turbulence, disturbing the resin separation boundary surface and anion This has been a cause of accelerating the contamination of the cation exchange resin into the exchange resin layer.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ion-exchange resin regeneration apparatus capable of reducing turbulence in the flow of backwash water in the vicinity of the resin separation interface and improving resin separation accuracy.

The ion-exchange resin regeneration apparatus of the present invention comprises a condensate demineralization tower, a cation-exchange resin regeneration tower, an anion-exchange resin regeneration tower, and a resin storage tank, which are connected by piping so as to allow resin transfer. In the exchange resin regeneration apparatus, a chemical injection part for supplying a regenerant is provided in a resin transfer pipe connecting an anion exchange resin outlet provided in the middle of the cation exchange resin regeneration tower in the vertical direction and the anion exchange resin regeneration tower. characterized by being connected.

In one aspect of the present invention, the chemical feeding section is provided vertically and has a chemical feeding pipe through which the regenerant flows downward, and a chemical feeding valve provided in the chemical feeding pipe.

In one aspect of the present invention, a tubular outlet is provided above the anion exchange resin outlet.

In the present invention, the anion exchange resin withdrawal pipe and the chemical injection pipe are shared. That is, the chemical injection pipe in the cation exchange resin regeneration tower is omitted by injecting the chemical solution from the anion exchange resin withdrawal pipe. Also preferably, the tubular outlet is located above the anion exchange resin outlet. As a result, the structure below the resin discharge port is eliminated, and the backwash water for separating the mixed resin is rectified.

In addition, the structure inside the cation exchange resin regeneration tower is simplified, and the production of the cation exchange resin regeneration tower is facilitated.

1 is a system diagram of an ion-exchange resin regeneration device according to an embodiment; FIG. FIG. 2 is a cross-sectional view of a portion of the cation exchange resin regeneration tower of FIG. 1; FIG. 3 is a cross-sectional view of the resin outlet of FIG. 2; (a) is a plan view of the radiation pipe, and (b) is a side view thereof. 1 is a system diagram of an ion-exchange resin regeneration device according to a conventional example; FIG. FIG. 3 is an explanatory diagram of a resin separation step in a cation exchange resin regeneration tower; FIG. 5 is a cross-sectional view showing a comparative example;

Embodiments will be described below with reference to the drawings. FIG. 1 is a system diagram showing an ion-exchange resin regeneration apparatus according to an embodiment, and a cation-exchange resin regeneration tower is shown as a schematic longitudinal section.

A lower water collecting plate 11 is installed in the lower part of the cation exchange resin regeneration tower 10, and resin is stored on the upper side of the lower water collecting plate 11. A resin discharge pipe 12 having a valve V8 is connected to the lower water collecting plate 11 . The bottom tube plate of the cation exchange resin regeneration tower 10 is connected to a later-described reclaimed water supply pipe 37 .

A resin introduction pipe 13 having a valve V4 is connected to the top of the cation exchange resin regeneration tower 10 . A drain section 14 made of a perforated pipe is installed in the upper part of the cation exchange resin regeneration tower 10, and a pipe 15 having a backwash water discharge valve V6 is connected to the drain section 14.

A translucent window (reference numerals omitted) is provided on a part of the side surface of the cation exchange resin regeneration tower 10 in the vertical direction. A sensor 17 is installed to detect the interface with the replacement resin. As the sensor 17, an optical sensor or the like that detects the interface based on the difference in color between the cation exchange resin and the anion exchange resin can be used, but it is not limited to this. As will be described later, based on the detection signal of this sensor 17, the reclaimed water supply valve V3 is controlled.

An anion exchange resin discharge port 20 and a tubular discharge port 18 (FIG. 2) are installed midway in the vertical direction in the cation exchange resin regeneration tower 10 . The anion exchange resin discharge port 20 is connected to one end side of a pipe 31 for discharging the anion exchange resin and for chemical injection via a branch pipe 30 .

The other end of the pipe 31 is connected to a reclaimed water supply unit via a reclaimed water valve V2 and pipes 32 and 33 . Examples of reclaimed water include pure water having an electrical conductivity of 1 mS/m or less.

An anion exchange resin extraction pipe 35 is branched from the middle of the pipe 31, and the pipe 35 is provided with a resin transfer valve V7.

A chemical injection pipe 36 is connected in the middle of the pipe 31, and the pipe 36 is provided with a chemical injection valve V1. A pipe 36 rises upward from the pipe 31 . The chemical feed valve V1 is provided at the bottom of the pipe 36, thereby reducing the amount of the chemical solution (sulfuric acid aqueous solution) remaining in the pipe 36 on the lower side than the valve V1.
The order of the branch position of the anion exchange resin extraction pipe 35 and the branch position of the chemical injection pipe 36 can be either, but if the anion exchange resin extraction pipe 35 is the one closer to the tower 10, the chemical Since there is a risk that the chemical solution will diffuse toward the anion exchange resin extraction pipe 35 during flushing after injection, it is preferable to reduce the risk by using the chemical injection pipe 36 near the tower 10 as shown in FIG.

Pipes 34 and 39 are branched from the reclaimed water supply pipe 33 . A pipe 34 is connected to the pipe 37 via a valve V3. A pipe 38 branches from the middle of the pipe 37, and the pipe 38 is provided with a drain valve V9. A pipe 39 is connected to the pipe 15 via a valve V5.

The configuration of the anion exchange resin outlet 20 will be described with reference to FIGS.

The one end of the pipe 31 is branched into a plurality of (preferably 3 to 6) radial branch pipes 30 . The tip side of each branch pipe 30 is bent downward. An anion exchange resin discharge port 20 is provided at the lower end of each branch pipe 30 on the tip side. The outlet 20 opens downward as shown in FIG. The discharge port 20 has a tapered cover 24 whose diameter increases downward.

The installation level of each outlet 20 is the same. That is, the lower ends (opening surfaces) of the discharge ports 20 are positioned on the same horizontal plane.

An outward flange-shaped flange 21 is provided at the lower end of the branch pipe 30 . A horizontal baffle 22 is arranged at a predetermined interval below the lower end opening of the branch pipe 30 and the flange 21 . Baffle 22 is attached to flange 21 by bolts 23 . A tapered cover 24 is provided so as to surround the outer periphery of the lower portion of the branch pipe 30 . The diameter of the cover 24 decreases upward. The upper end of cover 24 is connected to pipe 30 . A lower outer peripheral edge of the cover 24 is connected to an outer peripheral edge of the flange 21 .

As shown in FIG. 2, the tubular drain 18 consists of a horizontal perforated tube. The tubular outlet 18 is arranged below the horizontal radial portion of the branch pipe 30 and above the opening surface of the anion exchange resin outlet 20 . A drain pipe 18a is connected to the tubular drain port 18, and the pipe 18a is provided with a valve (not shown).

This ion-exchange resin regeneration apparatus is operated through the following resin extraction/separation process, regeneration process, and resin mixing/return process.

(1) Resin introduction V4 and V6 are opened, and the mixed resin is transferred from the demineralization tower to the cation exchange resin regeneration tower 10.

(2) Resin backwashing separation V4 is closed, V3 and V6 are open, and the reclaimed water is circulated upward into the tower 10 at LV 8 to 15 m/hr to separate the cation exchange resin and the anion exchange resin into two upper and lower layers. do.

(3) Adjusting the height of the resin separation boundary surface Adjust the opening of V3 and open V6 so that the height of the resin separation boundary surface detected by the sensor 17 is 150 degrees from the lower end of the baffle-type resin discharge port 20. Adjust the backwash flow rate so that the position is ~30 mm below.

(4) Extraction of anion exchange resin While continuing to adjust the opening of V3, open the resin transfer valve V7 and then close the backwash water discharge valve V6 at the top of the tower. Along with the backwash water flowing out from the anion exchange resin withdrawal pipe 35, the anion exchange resin is withdrawn and transferred to the anion exchange resin regeneration tower. During this time, V3 is adjusted so that the resin separation boundary surface has the same height.

After the withdrawal of the anion exchange resin is completed, the backwash water discharge valve V6 is opened and the resin transfer valve V7 is closed.

(5) Adjusting the height of the resin separation boundary interface Open V6 and adjust the opening of V3 so that the height of the resin separation boundary surface detected by the sensor 17 is the lower end (opening) of the baffle-type resin discharge port 20. Adjust the backwash flow rate so that the position is 0 to 20 mm below the surface).

(6) Re-extraction of anion exchange resin Open the resin transfer valve V7, and then close the backwash water discharge valve V6 at the top of the tower. Accompanied by the backwash water flowing out from the anion-exchange resin withdrawal pipe 35, the anion-exchange resin (and mixed cation-exchange resin) near the separation interface is transferred to the anion-exchange resin regeneration tower (anion-exchange resin regeneration tower open the resin receiving valve on the side). During this time, V3 is adjusted so that the resin separation boundary surface has the same height.

After the withdrawal of the anion exchange resin is completed, the backwash water discharge valve V6 is opened and the resin transfer valve V7 is closed. Close V3 to stop backflushing.

(7) Regeneration of cation exchange resin After the cation exchange resin settles, V6 is closed, V1 and V9 are opened, and sulfuric acid for regeneration is supplied for a predetermined time at a predetermined SV.

(8) Extrusion regeneration After that, V1 is closed, V2 and V9 are opened, and extrusion regeneration is performed with reclaimed water.

(9) Wash with water After that, close V2 and open V5 and V9 to wash with water.

In the present invention, instead of the anion exchange resin outlet 20, an anion exchange resin outlet 40 shown in FIG. 4 may be installed.

The anion exchange resin outlet 40 has a hollow boss portion 41 and a horizontal tubular body 42 extending radially from the boss portion 41 (eight radial directions in this embodiment). A resin inlet 43 is provided in the tubular body 42 . 4(a) is a plan view of an anion exchange resin discharge port, and FIG. 4(b) is a view taken along line BB of FIG. 4(a). A tubular drain port 18 is installed substantially horizontally above the tubular body 42 and below the pipe 31 .

[Example 1]
In the ion-exchange resin regeneration apparatus having the configuration shown in FIGS. 1 to 3, an anion-exchange resin outlet 20 is provided at a height of 1600 mm from the lower catchment plate 11 in the cation-exchange resin regeneration tower (inner diameter 1900 mm, tower height 5000 mm) 10. placed. The following ion exchange resins were used.

Cation exchange resin: Diaion UBk14HK (layer height about 1300 mm)
Anion exchange resin: Diaion PA312LOH (layer height about 500 mm)

3900 L of the cation exchange resin and 1500 L of the anion exchange resin were placed in the cation exchange resin regeneration tower 10 in a mixed state. After that, the above steps (1) to (9) were carried out as follows. Then, the amount of the cation exchange resin mixed in the anion exchange resin separated and extracted from the cation exchange resin regeneration tower 10 was calculated as the cation exchange resin mixing ratio (% by volume) to verify the effect. The results are shown in Table 1 together with the regeneration rate.

After backwash separation is performed by opening the backwash water discharge valve V6 to separate the cation exchange resin and the anion exchange resin, the sensor 17 detects that the resin separation boundary surface is positioned 110 mm downward from the lower end of the anion exchange resin discharge port 20. The backwash flow rate was adjusted with V3 as follows. Backwashing was continued, and after opening the resin transfer valve V7, the backwash water discharge valve V6 was closed to transfer the anion exchange resin. The resin during transfer was sampled and the cation exchange resin mixing ratio contained in the anion exchange resin was measured.

Next, the backwash LV was adjusted so that the position of the resin separation boundary surface was 20 mm downward from the lower end of the resin discharge port 20, and the resin was transferred in the vicinity of the resin separation boundary surface. After 20 minutes of transfer, the backwash was stopped and the cation exchange resin was allowed to settle.

Next, the chemical feed valve V1 and the drain valve V9 were opened to pass 6% sulfuric acid at SV3 (1/Hr) for 45 minutes. Next, V1 was closed, reclaimed water valve V2 was opened, and reclaimed water was passed at SV3 (1/Hr) for 60 minutes. Washing was performed by raising the SV of the reclaimed water to 30 (1/Hr). Thereafter, air was supplied into the tower to mix the resin, and the homogeneous resin was sampled and the regeneration rate was determined from the RH ratio.

[Example 2]
The same operation as in Example 1 was performed except that the configuration near the anion exchange resin outlet was changed as shown in FIG. Table 1 shows the measurement results of the cation exchange resin mixing rate and regeneration rate.

[Comparative Example 1]
As shown in FIG. 7, the tubular outlet 18 is located 200 mm lower than the anion exchange resin outlet 20 in FIG. A radial tubular drug injection port (same shape as in FIG. 4) 50 was arranged 150 mm below the tubular discharge port 18 . The chemical injection pipe 36 was connected not to the pipe 31 but to the pipe 51 connected to the tubular medicine injection port 50 . Also, the pipe 51 was connected to the pipe 39 via the valve V10 and the pipe 52 .

In the same manner as in Example 1, the backwash water discharge valve V6 is opened to perform backwash separation to separate the cation exchange resin and the anion exchange resin. The backwash flow rate was adjusted by V3 so as to be 110 mm below the lower end. Backwashing was continued, and after opening the resin transfer valve V7, the backwash water discharge valve V6 was closed to transfer the anion exchange resin. The resin during transfer was sampled and the cation exchange resin mixing ratio contained in the anion exchange resin was measured. Next, the backwash LV was adjusted so that the position of the resin separation boundary surface was 20 mm below the lower end of the resin discharge port 20, and the resin was transferred near the resin separation boundary surface. After 20 minutes of transfer, the backwash was stopped and the cation exchange resin was allowed to settle.

Open chemical injection valve V1 and drain valve V9, pass 6% sulfuric acid at SV3 (1/Hr) for 45 minutes, close V1, open reclaimed water valve V10, and reclaimed water at SV3 (1/Hr) for 60 minutes. water flowed. Washing was performed by raising the SV of the reclaimed water to 30 (1/Hr). Thereafter, air was supplied into the tower to mix the resin, and the homogeneous resin was sampled and the regeneration rate was determined from the RH ratio.

[Comparative Example 2]
In Comparative Example 1, the anion exchange resin discharge port 20 was replaced with the radial anion exchange resin discharge port 40 shown in FIG. Otherwise, the same operation as in Comparative Example 1 was performed. Table 1 shows the measurement results of the cation exchange resin mixing rate and regeneration rate.

<Results and discussion>
In Table 1, when the allowable value of the mixing rate is 0.02 vol% or less, ◯ is displayed, and when it exceeds the allowable value, x is displayed. Similarly, when the reproduction ratio is 80% or more, the value is indicated by ◯, and when the value is less than 80%, the value is indicated by ×.

In Examples 1 and 2, both resin mixing rate and regeneration rate are satisfactory. On the other hand, Comparative Examples 1 and 2 showed satisfactory performance in terms of regeneration rate, but the resin mixing rate exceeded the allowable value. The reason for this is thought to be that the presence of the internal structure below the anion resin discharge port causes turbulence in the backwash water flow, inhibiting the resin separation action.

1 condensate demineralization tower 3, 10 cation exchange resin regeneration tower 4 anion exchange resin transfer pipe 4a anion exchange resin outlet 5 anion exchange resin regeneration tower 8 resin storage tank 17 resin interface detection sensor 18 tubular drainage port 20, 40 anion exchange resin Drain port 22 Baffle 50 Chemical injection port

Claims (3)

In an ion-exchange resin regeneration device for condensate demineralization, in which a condensate demineralization tower, a cation exchange resin regeneration tower, an anion exchange resin regeneration tower, and a resin storage tank are connected by piping so as to allow resin transfer,
A chemical injection unit for supplying a regenerant is connected to a resin transfer pipe connecting an anion exchange resin discharge port provided in the vertical direction of the cation exchange resin regeneration tower and the anion exchange resin regeneration tower. An ion exchange resin regeneration device characterized by: 2. The chemical-feeding unit according to claim 1, wherein the chemical-feeding unit is provided vertically and has a chemical-feeding pipe through which the regenerant flows downward, and a chemical-feeding valve provided in the chemical-feeding pipe. ion exchange resin regenerator. 3. An ion-exchange resin regeneration apparatus according to claim 1, wherein a tubular drainage port is provided at a position above said anion-exchange resin outlet.

Images