JPH05200383A - Auxiliary type filtrating and desalting device - Google Patents

Abstract

PURPOSE:To prevent organic impurities from being introduced from an equipment in which powdery ion exchange resin is used by providing a system for discharging the water held in a tower to a waste disposal equipment from a filtrating and desalting tower, supplying raw water not less than the amount of water held in the tower before passing water to perform replacement of water in the tower, draining the water held in the tower and thereafter passing water. CONSTITUTION:A system is provided to a waste disposal system from the outlet pipeline of a filtrating and desalting tower. After the filtrating and desalting tower 20 is back-washed and precoated, an outlet valve 22, an inlet valve 23 of precoat, an outlet valve 24 of precoat, a drain valve 25 of backwash and a vent valve 26 of backwash are closed. An inlet valve 21 is opened and the pressure of the system is exerted. While keeping a stand-by state for holding a precoat layer in a state wherein a holding pump 27 is operated, a valve 31 for replacing water held in the tower is opened to extrude and replace the water held in the tower by raw water. Thereby, organic impurities eluted from resin, fiber such as nylon cut off from a fiber element and the additive of precoat material are discharged to the outside of the system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is to pre-coat a filter aid on the surface of a filter element to allow water to pass through the filter layer of the aid,
In an auxiliary material type filter desalting device in which a large number of filter elements are installed to remove the filter water from the inside of the filter element to perform filter desalting, particularly, organic impurities eluted from the ion exchange resin, fiber impurities from the fiber element and precoat material. The present invention relates to an auxiliary material type filter desalting apparatus which enhances the purity of treated water by discharging the additives and the like of the above.

[0002]

2. Description of the Related Art A water treatment system of a condensate purification system and a reactor water purification system of a nuclear power plant (BWR) is shown in the figure. In this figure, steam generated in the reactor 1 (about 290 ° C, about 70kg / cm ² )
Drives the turbine 3 via the steam pipe 2 to generate electricity,
After that, it is condensed in the condenser 4 and becomes condensed water. Condensed water from the condenser 4 is guided by a pipe 5 and sent to a condensate filtration desalination apparatus 7 by a condensate pump 6. In condensate filter demineralizer device 7, the main component in the general term of the cladding (usually corrosion products and clad with mainly fine suspension that does not pass through the 0.45μm Millipore filter generated in the plant Fe ₂ O ₃ , Fe ₃ O ₄
Etc. ) And nuclide ions are mixed in a cylindrical filter element with powdered ion-exchange resin of cation and anion at a specific ratio, and the resin layer is pre-coated evenly on the outer diameter surface with a thickness of several mm to desalinate. To purify. The water purified by the condensate filtration desalination apparatus 7 is then sent to the condensate deionization apparatus 8 and reconstituted by a resin layer containing granular ion exchange resins of anions and cations in the condensate deionization tower. Residual cladding and nuclide ions that have not been removed by the water filtration desalination apparatus 7 are captured and desalted. The purified water that has passed through the condensate demineralizer 8 is heated by the low-pressure feed water heater 10 through the condensate booster pump 9 and is sent to the high-pressure feed water heater 12 by the feed water pump 11, and is heated again at high pressure and then the nuclear reactor. Return to 1.

Thus, the steam generated in the reactor 1 drives the turbine 3 and then purifies the condensate and returns it to the reactor 1. Therefore, the steam is constantly circulated in the condensate purification system. On the other hand, the reactor water of the nuclear reactor 1 is sent to the reactor water purification system filtration desalination apparatus 17 and the reactor water purification system desalination apparatus 18 (some plants are not installed) through a reactor water purification system pipe 15 by a pump 16. After being cleaned, it is configured to return to the reactor again. The structure of the reactor water purification system filter desalting device 17 is the same as that of the condensate water filter desalting device 7, and is designed to circulate the reactor water for filter desalting and purification.

Here, the condensate filtration desalination apparatus 7 and the reactor water purification system filtration desalination apparatus 17 are mixed with a powdery cation exchange resin at a certain ratio as described above, and are made of nylon fiber or porous stainless steel. Built-in pre-coated with about 1 kg of resin per 1 m ² of filtration area on the manufactured element. At the time of precoating, in order to make the resin layer uniform, acrylic acid-based chemicals are added, or precoating with a low-concentration slurry is performed. After the precoating operation, raw water is introduced into the filter desalting device to start the treatment. FIG. 3 shows a schematic system of a normal filtration desalination apparatus. The filter desalting apparatus is composed of a plurality of filter desalting towers 20, and the filter desalting towers 20 are used in parallel for processing. As the condensate is treated, the clad in the condensate is captured in the precoat layer, and the filtration pressure rapidly increases accordingly. Normally, when the filtration pressure reaches about 2 kg / cm ² , the filtration desalting tower 20 stops the treatment and backwashes the element. Then, the element is again precoated with a new resin, and the process is restarted. However, in the case of powdered resin, the resin removed from the element by backwashing is generally difficult to regenerate, and therefore it is generally discarded after only one use.

[0005] Here, the filter desalting tower 20 and the condensate demineralizing tower 3
Organic impurities (total organic carbon TOC) tend to be eluted from the resin loaded in No. 5 as shown in FIG. The organic impurity is C-SO ₃ H and the like, becomes a factor to which they vary the result reactor water conductivity in the flowing into the reactor pyrolyzed SO ₄ ^2-like.

As a countermeasure for preventing the inflow of organic impurities from the resin into the reactor, the condensate demineralization tower 35, which has a large amount of resin and a large amount of organic impurities, is conventionally used. FIG. 5 shows an example of TOC concentration in the tower when the condensate demineralization tower 35 is stored, but when the demineralization tower is stored, TOC is eluted from the resin held in the tower, TOC in the tower
The concentration increases, and after about 30 days, it becomes about 2000 mg / m ³ . When water is passed through one desalting tower at this concentration and TOC flows into the reactor, the sulfate radicals (S
O ₄ ²⁻ ) is expected to be about 3-5 mg / l. For this reason, in the desalting tower 35, the water held in the tower is discharged to the outside of the system before passing water. Figure 6
It shows the structure around the desalting tower. The drain of the retained water in the tower drains the retained water in the tower by opening the valve 36 to the waste treatment facility and opening the valve 37 of the compressed air. At this time, if the entire amount is drained, air will be mixed into the resin layer, so the resin layer surface will be drained, and after closing the valve 36 to the waste treatment facility and the valve 37 for compressed air, the valve 38 from the makeup water facility is closed.
Is opened to fill the desalting tower 35 with water. By repeating this operation of drainage and full water several times (usually 3 to 5 times), impurities eluted from the resin are discharged out of the system together with the water retained in the tower.

Here, conventionally, only the condensate demineralizing tower 35 having a large amount of resin has been considered to remove the organic impurities.
In the condensate filtration desalination apparatus 7 and the reactor water purification system filtration desalination apparatus 17 that have other powdered resins, not only this operation is not taken into consideration, but also the discharge system of organic impurities out of the system is taken into consideration. I didn't. In addition, due to the fact that nylon fibers, polypropylene fibers, etc. are used as the element material, the effect of thermal decomposition in the nuclear reactor due to the outflow of fibers, and for the proper floc formation of the powder ion exchange resin in the precoat type filter desalting tower. Additives, which are acrylic acid type copolymers used, also cause water quality fluctuations, and therefore, measures against spillage were also necessary for these.

A related device of this type is disclosed in, for example, Japanese Patent Laid-Open No. 3-31799.

[0009]

In recent nuclear power plants, there is a demand for maintaining high-purity water quality in nuclear reactors, and the factors that cause fluctuations in water quality are eliminated. This prior art was intended only for the condensate demineralizer with a large amount of resin in consideration of organic impurities (TOC, etc.) eluted from the resin, but the system supplied to the reactor has a powder ion exchange resin. Also, regarding condensate filtration desalination equipment and reactor water purification system filtration desalination equipment, which are equipments where organic impurities such as fiber elements may flow out, the organic impurities etc. from this equipment heats up in the reactor. The water quality change due to sulfate, ammonia, and acrylic acid when decomposed was not taken into consideration due to the small amount.

An object of the present invention is to provide a condensate filtration desalination system and a reactor water material purification system filtration desalination system in order to eliminate the factors of fluctuations in the reactor water quality in order to satisfy recent requirements for high-purity water quality of reactor water. Thus, it is a system equipment configuration and operation method for preventing the inflow of organic impurities and the like from the equipment using the powder ion exchange resin into the system.

[0011]

The present invention relates to a precoat type filter desalting apparatus for precoating a powder ion exchange resin, before the passage of water when processing primary cooling water (condensate water, reactor water) of a nuclear power plant. In addition, organic impurities (TO
It is an auxiliary material type filter desalination apparatus, characterized in that the stored water containing C) is discharged to the outside of the system and then passed through.

Organic impurities (TO
A system to the waste treatment facility is provided as a means for discharging the retained water containing C) to the outside of the system, and raw water (condensate water, reactor water, etc.) or replenishment is provided to prevent the precoat resin layer of the powder ion exchange resin from peeling Retained water containing organic impurities by continuously supplying makeup water from the water facility (in this case, newly installing a supply system from the makeup water facility) and continuously draining it to replace the water in the tower. Is discharged to the outside of the grid.
In this case, the amount of raw water or make-up water supplied should be at least the amount of water held in the tower.

[0013]

In the filter desalting tower, the powder ion-exchange resin precoated on the element by passing the raw water adsorbs the clad component and the ionic component. When this filter desalting tower is stored in a state where the resin is pre-coated, such as during a plant regular inspection and during a preliminary tower operation, organic impurities are eluted from the resin and are retained in the tower. In addition, organic impurities are eluted from the newly powdered ion-exchange resin that has been backwashed and pre-coated and newly pre-coated, and an acrylic acid (CH ₂ CHCOOH) additive has been added for proper floc formation. The acrylic acid remaining without being adsorbed by the resin is retained in the tower. Nylon fibers may also be used for the elements, and some of the nylon fibers are cut off and float in the tower. When these flow out into the system due to water flow, they are brought into the reactor, where they are converted to sulfate, ammonia, and sulfonic acid due to thermal decomposition, etc., and become a factor that affects the water quality of the reactor water.

For this reason, a system for discharging the water contained in the tower to a waste treatment facility outside the system is provided before passing through the filter desalting tower, and raw water (condensate, reactor water) or makeup water (in this case, A new supply system from the makeup water facility is installed to replace the water in the tower to remove organic impurities from the resin, elements, additives, etc. to the reactor primary cooling water (condensate, reactor). Water), which can be discharged outside the system, can eliminate the factors that affect the water quality of reactor water.

[0015]

EXAMPLES Examples of the present invention will be specifically described below.

The above technical contents do not change. That is, there are a condensate filtration desalination device 7, a condensate deionization device 8, a reactor water purification system filtration desalination device 17, and a reactor water purification system desalination device 18 as devices for treating the reactor primary cooling water. The condensate and the reactor water are purified by.

Here, the resin loaded in these devices has the following structure, and the sulfo group (--SO ₃ H) among them is eluted in water.

[0018]

[Chemical 1]

When this sulfone group flows into the nuclear reactor, it is thermally decomposed to generate sulfate radicals (SO ₄ ²⁻ ). Similarly, the nylon fiber used for the element is diamine (N
H ₂ (CH ₂ ) mNH ₂ ) and a dibasic acid having a carbon number of n (HOOC (C
H ₂₎ polycondensates of _n-2 COOH), when it is decomposed in the reactor ammonia (NH ₄ OH), nitrate (NO ₃ ^-)
It is possible that In addition, acrylic acid (CH ₂ CHCO) used as an additive for the precoat material
OH) type chemicals also change the conductivity when they flow into the reactor.

From the above, even in the filter desalting apparatus, it is necessary to drain the water held in the tower and replace it with water before passing water.

FIG. 1 shows a system diagram of a filtration desalination apparatus provided with a system for discharging the water retained in the tower to the outside of the system. The method of treating raw water, the method of pre-coating, etc. are not replaced with the conventional technology.

Here, the point different from the conventional one is that a system is installed from the outlet pipe of the filter desalting tower to the waste treatment system. After backwashing and precoating the filter desalting tower 20, the outlet valve 2
2, the precoat inlet valve 23, the precoat outlet valve 24, the backwash drain valve 25, and the backwash vent valve 26 are closed, and the inlet valve 21
Is opened to hold the precoat layer while the holding pump 27 is operated with the system pressure applied. When water is passed from this state, the outlet valve 22 is normally opened, but in the present invention, the water in the tower is replaced before this water is passed. That is,
With the inlet valve 21 open, open the water replacement valve 31 in the tower,
The water held in the tower is extruded and replaced by raw water. At this time, the raw water is made to flow from the outside to the inside of the element to prevent the precoat layer from peeling off, as in the case of flowing water, and to supply the raw water in an amount equal to or more than the water content in the tower (about 1.3 times or more). To do.

According to the present invention, a system for discharging from the filter desalting tower 20 to the waste treatment facility is provided, and raw water in an amount equal to or more than the amount of water held in the tower is supplied to replace the water in the tower with water before passing water. After draining the water, organic impurities eluted from the resin by passing water, nylon fiber cut from the fiber element,
Since the additives and the like of the precoat material are discharged to the outside of the system, they are not mixed into the reactor primary cooling water together with the water flow of the filter desalting tower 20 and flow into the reactor 1, and as a result, Water quality fluctuation can be suppressed.

FIG. 7 is an application example of the present invention, in which the discharge system for discharging water held in the filter desalting tower is discharged to a backwash receiving tank. That is, the outlet of the tower internal water replacement valve 31 is connected to the backwash drain pipe, and the tower internal water is temporarily received in the backwash receiving tank and then discharged to the waste treatment facility.

FIGS. 8 and 9 show that make-up water is used to replace the water held in the filter desalting tower described in FIGS. 1 and 7. That is, a make-up water supply system from a make-up water facility is provided between the inlet valve 21 and the filter desalting tower 20, the inlet valve 21 is closed when the water held in the tower is replaced with water, and then the make-up water supply valve 32 is opened.
Make-up water is supplied to the inside of the tower, and the held water in the tower is discharged from the held water replacement valve 31 to the waste treatment facility.

[0026]

According to the present invention, a system for discharging the retained water in the tower to the waste treatment facility from the filter desalting tower such as the condensate filtration desalination apparatus and the reactor water purification system filtration desalination apparatus is provided. The raw water or makeup water that exceeds the amount of water in the tower is supplied before water to replace the water in the tower, drain the water in the tower, and then pass water to cut off organic impurities and fiber elements eluted from the resin. Since such fibers such as nylon, additives of precoat material, etc. are discharged to the outside of the system, they will not be mixed with the primary cooling water of the reactor together with the water passing through the filter desalting tower and flow into the reactor. As a result, fluctuations in water quality of reactor water can be suppressed.

[Brief description of drawings]

FIG. 1 is a system diagram of a filtration desalination apparatus provided with a drain system to a waste treatment facility for water held in a filtration desalination tower.

FIG. 2 is a system diagram of a boiling water nuclear power plant.

FIG. 3 is a system diagram of a filter desalting apparatus.

FIG. 4 is an explanatory diagram of a relationship between the elution rate of total organic carbon (TOC) of a resin and the number of immersion days.

FIG. 5 is an explanatory diagram of the relationship between the number of days of storage in the desalting tower and the amount of total organic carbon (TOC).

FIG. 6 is a system diagram around a desalting tower.

FIG. 7 is a system diagram of a filtration desalination apparatus provided with a system for draining the water retained in the filtration desalination tower to a backwash receiving tank.

FIG. 8 is a system diagram of a filtration desalination apparatus in which a supply system from a makeup water facility is provided to replace the water held in the filtration desalination tower and a drain system is provided to a waste treatment facility.

FIG. 9 is a system diagram of a filtration desalination apparatus in which a system for supplying water from a makeup water facility is provided for replacing the water held in the filtration desalination tower and a system for draining to a backwash tank.

[Explanation of symbols]

20 ... Filtration desalting tower, 21 ... Inlet valve, 22 ... Outlet valve, 23
… Precoat inlet valve, 24… Precoat outlet valve, 25…
Backwash drain valve, 26 ... Backwash vent valve, 27 ... Holding pump, 29 ... Precoat tank, 30 ... Backwash receiving tank.

Claims (4)

[Claims] 1. A filter aid is pre-coated on the surface, raw water is allowed to permeate through the aid filter layer, and a large number of filter elements for removing filtered water from the inside of the filter element to perform desalination are installed, and powder ions are used as the filter aid. In an auxiliary material type filter desalination apparatus using an exchange resin, the auxiliary material type filter desalination apparatus is characterized in that the water held in the tower is discharged to the outside of the system using raw water before water is passed. Salt equipment. 2. The auxiliary material type filter desalination apparatus according to claim 1, wherein a system is provided for discharging the retained water in the filter desalination tower to the outside of the system to the waste treatment facility from the outlet side of the filter desalination tower. . 3. The system according to claim 1, wherein a system from the outlet side of the filter desalting tower to the backwash receiving tank is provided to discharge the water retained in the filter desalting tower to the outside of the system, and the water retained in the tower is backwashed. An auxiliary material type filter desalination device that discharges waste to a waste treatment facility via a tank. 4. The tower according to claim 1, 2 or 3, wherein a system for supplying make-up water is provided on the inlet side of the filter desalting tower in order to discharge the retained water in the filter desalting tower to the outside of the system. An auxiliary material type filter desalination device that discharges the water held inside the system.