JPH1054898A - Device for maintaining quality of condensate stored in condensate tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the quality of a condensate stored in a condensate tank at a high level by installing a TOC(total organic carbon) resolving device to a pure water pipeline and resolving the TOC of the pure water supplied to the condensate tank. SOLUTION: Raw water pumped up from a water source 18, such as the sea, river, etc., is purified by means of a water purifying device 19. In order to the reduce the TOC concentration, a TOC resolving device 24 composed of an ozonizer 30 which generates ozone by hydrolysis, a hollow fiber film filter 25, and a demineralizing tower 26 is installed to a pure water supply pipeline 20 on the downstream side of the device 19. The quality of the condensate stored in a condensate tank 17 is maintained at a high level by resolving the TOC of the pure water flowing in the tank 17. In addition, the condensate in the tank 17 is circulated between the tank 17 and the resolving device 24 through a condensate circulating pipeline 34 by means of a condensate circulating pump 33 even when the TOC concentration of the condensate stored in the tank 17 is high. At the same time, the TOC is resolved by injecting the ozone generated from the ozonizer 30 into the condensate stored in the tank 17 through an ozone injecting pipeline 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a TOC in storage water in a condensate storage tank installed in a nuclear power plant.
The present invention relates to a water quality maintenance device for a condensate storage tank that decomposes and removes (total organic carbon) to maintain the purity of stored water.

[0002]

2. Description of the Related Art FIG. 2 illustrates a primary system of a conventional boiling water nuclear power plant, FIG. 3 illustrates a means for maintaining purity of stored water in a condensate storage tank, and FIG. The relationship with the conductivity will be described.

In FIG. 2, steam generated in a nuclear reactor 1 is sent to a turbine 3 via a main steam pipe 2, and a generator 4 is rotated to generate power. The steam that has driven the turbine 3 is condensed in the condenser 5 to be condensed.

The condensate is pressurized by a low-pressure condensate pump 6, passes through an air extractor 7 and a ground steam condenser 8, and has a condensate filtration device 9 and a condensate desalination device 10 installed in a condensate purification system. Removes impurities. The condensate purified by the condensate desalination device 10 is further pressurized by a high-pressure condensate pump 11 and sent to a low-pressure feedwater heater 12 to be heated.

Then, the pressure is further increased by a water supply pump 13, heated through a high pressure water heater 14, and supplied to the reactor 1 through a water supply pipe 15. Note that hydrogen is injected for structural equipment integrity in the nuclear reactor 1, and the hydrogen is injected at a hydrogen injection point 16 between the condensate desalination device 10 and the high-pressure condensate pump 11.

In the boiling water nuclear power plant, a condensate storage tank 17 shown in FIG. 3 is connected between a condensate desalination unit 10 and a high-pressure condensate pump 11 via a branch pipe. FIG. 3 shows a basic system diagram for storing pure water obtained by purifying raw water from a water source 18 by a pure water producing apparatus 19 in a condensate storage tank 17.

[0007] In FIG. 3, usually, raw water pumped from a water source 1 such as seawater or river water is purified by a pure water production apparatus 19, and the condensed water storage tank 17 is directly passed through a pure water supply pipe 20.
After being stored in the nuclear power plant, it is transferred to each device 22 in the nuclear power plant via the condensate supply pump 21. The plant excess water from each device 22 is returned to the condensate storage tank 17 by a feedback pipe 23.

In the boiling water nuclear power plant shown in FIG. 2, after the periodic inspection of the plant is completed, the condensate stored in the condensate storage tank 17 shown in FIG. Fill with water. The purification before starting the plant is performed by the condensate filtration device 9 and the condensate desalination device 10 of the condensate purification system.

At the time of this purification, the T
When the OC is high, the condensate filtration unit 9 and the condensate desalination unit 10
However, it may be difficult to completely remove the TOC component. For this reason, the TOC concentration is checked before filling the plant. If the TOC concentration is high, the total amount of water in the condensate storage tank 17 (about 2000 to 3
000m ³ ) is blown and stored again from the pure water production apparatus 19 to confirm that the TOC is low, and then the plant is refilled. The flow of water after the completion of the purification before the start of the plant and the start of the plant is as described in FIG.

[0010]

A conventional pure water producing apparatus is constructed by combining filtration and desalting. That is, as shown in FIG. 3, pure water is produced from the raw water by the pure water producing device 17 and the condensate storage tank 17 is passed through the pure water supply pipe 20.
To be stored. The pure water production apparatus 17 is filled with an ion exchange resin, and the desalination treatment of the raw water is performed using the ion exchange resin.

This ion exchange resin elutes organic impurities from the resin matrix due to aging deterioration and the like. This organic impurity is called TOC (Total Organic Carbon). When the TOC generated by the ion exchange resin is decomposed, sulfate and nitrate ions are generated, which has an adverse effect such as corrosion of plant constituent materials.

FIG. 4 shows the relationship between the TOC concentration of the condensate water and the reactor water conductivity and time. In FIG. 4, the vertical axis is the TOC concentration on the left side, the electrical conductivity is on the right side, the horizontal axis is the date and time, the symbol a is reactor water electrical conductivity (TOC high), b is reactor water electrical conductivity (TOC low), and c is TOC. The concentration (high) and d indicate the TOC concentration (low). The condensed water is the stored water in the condensed water storage tank 17, and the reactor water is the cooling water supplied to the reactor 1.

As is clear from FIG. 4, when the TOC concentration (high) c of the condensate is about 150 ppb, the reactor water conductivity TOC
(High) a becomes high immediately after the start of the plant. In the case of the TOC concentration (low) d of the condensed water, it becomes low like the reactor water conductivity TOC (low) b.

Generally, a nuclear power plant has a condensate storage tank 17 for storing water used as make-up water at the time of starting the plant. For this reason, when water is filled at the time of starting the plant with make-up water having a large amount of TOC components, an event that the water quality at the time of starting is deteriorated occurs, and reducing the TOC has been a problem.

The condensate storage tank 17 collects surplus water from each device 22 of the plant. There is a possibility that TOC components such as the rust preventive agent and oil used during the periodic inspection may be introduced into the surplus water and may flow into the surplus water. Therefore, it is an issue to establish a method for reducing the TOC by using the condensate storage tank water alone. .

The present invention has been made to solve the above-mentioned problems, and it is possible to decompose and remove the TOC component of the storage water in the condensate storage tank to maintain the quality of the water in the condensate storage tank high. Accordingly, an object of the present invention is to provide a water quality maintaining device in a condensate storage tank that can effectively use hydrogen generated during water decomposition.

[0017]

According to a first aspect of the present invention, there is provided a pure water producing apparatus for purifying raw water, a pure water supply pipe connected to the pure water producing apparatus, and a pure water supply pipe connected downstream of the pure water supply pipe. And a TOC (total organic carbon) decomposer having an ozone generator provided in the pure water supply pipe.

According to the present invention, the TOC of pure water supplied to the condensate storage tank is decomposed with ozone by the ozone generator by water decomposition, and the water quality of the condensate storage tank can be maintained high.

According to a second aspect of the present invention, the TOC decomposing apparatus includes a hollow fiber membrane filter connected to the pure water supply pipe, and a desalination tower filled with an ion exchange resin connected to the hollow fiber membrane filter. An ozone generator connected to the outlet side of the desalination tower via a desalinated water supply pipe, and ozone injection connected to the ozone outlet side of the ozone generator and the pure water supply pipe on the inlet side of the condensate storage tank. It is characterized by comprising a pipe.

According to the present invention, the purity of pure water purified by the pure water producing apparatus can be further improved by the hollow fiber membrane filter and the desalination tower, the efficiency of TOC decomposition by ozone is increased, and condensate is stored. The water quality of the tank can be maintained.

A third aspect of the present invention is characterized in that a circulation pipe is provided for connecting the condensate storage tank and a pure water supply pipe between the pure water producing apparatus and the TOC decomposing apparatus. According to the present invention, TOC decomposed by ozone
Since the stored water containing the components can be fed back through the circulation pipe and removed by the hollow fiber membrane filter and the desalination tower, the water quality of the condensate storage tank can be further maintained.

The invention of claim 4 is characterized in that the TOC decomposing device is provided in a condensate purification system of a nuclear power plant. According to the present invention, the ozone generated from the ozone generator can be supplied to the downstream of the condensate desalination apparatus of the condensate purification system.
Decomposition can be performed.

A fifth aspect of the present invention is characterized in that the TOC decomposing apparatus is connected to a heat source in a nuclear power plant and a hydrogen source at the time of injecting hydrogen into feed water by piping. ADVANTAGE OF THE INVENTION According to this invention, the hydrogen generated from an ozone generator can be burned and the thermal energy can be utilized for the heat source of a nuclear power plant. Further, the hydrogen source can be an effective hydrogen source for maintaining the integrity of the equipment in the reactor.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a water quality maintaining device for a condensate storage tank according to the present invention will be described with reference to FIG. FIG.
3, the same parts as those in FIG. 3 are denoted by the same reference numerals, and the description of the overlapping parts will be omitted.

The embodiment of the present invention is different from the conventional example shown in FIG. 3 in that a TOC decomposing device 24 is provided in a pure water supply pipe 20 connecting a pure water producing device 19 and a condensate storage tank 17. By decomposing the TOC in the pure water flowing into the water storage tank 17, the TOC concentration of the storage water in the condensate storage tank 17 is reduced to maintain the water quality at high purity. The purpose of the present invention is to maintain the water quality of high purity.

The TOC decomposing device 20 includes a hollow fiber membrane filter 25 and a desalting tower 26 connected in series to a pure water supply pipe 20 downstream of the pure water producing device 19. A bypass pipe having a bypass valve 27 on the inlet side of the hollow fiber membrane filter 25 and the outlet side of the desalination tower 26
28 are provided. A desalinated water supply pipe 29 is connected to the outlet side of the desalination tower 26, and an ozone generator is connected to the desalinated water supply pipe 29.
30 is connected.

The ozone outlet side of the ozone generator 30 and the downstream side of the bypass pipe 28 on the desalination tower 26 side are connected by an ozone injection pipe 31. A hydrogen gas outlet pipe 32 is connected to the ozone generator 30. Condensate storage tank 17 and pure water production equipment
A circulation pipe 34 having a condensate circulation pump 33 is provided between the circulation pipe 34 and the circulation pipe 19.

Next, the operation of the present embodiment will be described. As shown in FIG. 1, raw water pumped from a water source 18 such as seawater or river water is purified by a pure water production apparatus 19, stored in a condensate storage tank 17 as it is, and passed through a condensate supply pump 21,
In the present embodiment, in order to reduce the TOC concentration, an ozone generator 30 by water splitting and a hollow fiber membrane filter 25 are provided downstream of the pure water production apparatus 19 in order to reduce the TOC concentration.
And a TOC decomposer 24 comprising a desalination tower 26.

FIG. 1 shows a system in which the TOC decomposer 24 is implemented, in which water in the condensate storage tank 17 is circulated between the TOC decomposer 24 and the condensate storage tank 17 using a condensate circulation pipe 34. Thus, even when the TOC concentration of the condensed water already stored is high, the circulation operation is performed via the condensate circulation pump 33. At the same time, the ozone generated from the ozone generator 30 is supplied to the ozone injection pipe 31.
And returned to the condensate storage tank 17 to decompose the TOC by the decomposing action of ozone.

By the circulation operation, the hollow fiber membrane filter 25 and the desalination tower
The TOC is decomposed by passing through 26 to remove ionic impurities such as sulfate ions and nitrate ions generated. Thereby, the water quality of the condensate storage tank 17 can be maintained at high purity. This circulation operation can be performed by the condensate storage tank 17 alone. In this circulation operation, the hollow fiber membrane filter 25 and the desalination tower 26 can be bypassed by the bypass pipe 28,
Injection of ozone alone is also possible.

Further, the TOC decomposing device 24 can be provided in a condensate purification system of a nuclear power plant. That is, by directly supplying ozone generated from the ozone generator 30 to the downstream of the plurality of desalination devices in the plant, it becomes possible to perform TOC decomposition during the purification operation before starting the plant.

Further, the TOC decomposer 24 can be connected to a heat source in the nuclear power plant and a hydrogen source at the time of injecting hydrogen into feed water. That is, the ozone generator 30 by water decomposition generates hydrogen simultaneously with the generation of ozone. The thermal energy obtained by burning the hydrogen can be used as heat supply in the place.

In the case of a nuclear power plant, it has been confirmed in recent years that hydrogen injection is effective for maintaining the integrity of in-furnace equipment. Hydrogen generated from the ozone generator 30 can be used as the hydrogen source.

[0034]

According to the present invention, the TOC flowing into the condensate storage tank is decomposed with ozone by the TOC decomposer capable of producing pure water by combining the ozone generator by water decomposition, and the stored water in the condensate storage tank is decomposed. To reduce the TOC concentration.

Further, a TOC decomposing device, which is a combination of a purifying device including a hollow fiber membrane and an ion exchange resin therein and an ozone generating device by water splitting, is installed downstream of the pure water producing device, and flows into a condensate storage tank. By decomposing the TOC, the quality of the stored water in the condensate storage tank can be maintained at high purity, and the water quality of the reactor water can be maintained at high purity.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of an apparatus for maintaining the purity of water in a storage tank according to the present invention.

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

FIG. 3 is a basic system diagram for storing pure water in a condensate storage tank provided on the downstream side of the condensate desalination apparatus of the plant of FIG. 2;

FIG. 4 is a characteristic diagram showing a relationship between TOC in reactor water and conductivity in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor, 2 ... Main steam pipe, 3 ... Turbine, 4 ... Generator, 5 ... Main condenser, 6 ... Low pressure condenser pump, 7 ... Air extractor, 8 ... Ground steam condenser, 9 ... Condensate filtration device, 10 ...
Condensate desalination equipment, 11 high-pressure condensate pump, 12 low-pressure feedwater heater, 13 feedwater pump, 14 high-pressure feedwater heater, 15 feedwater pipe, 16 hydrogen supply point, 17 condensate storage tank, 18 ... water source,
19 ... pure water production equipment, 20 ... supply water supply piping, 21 ... condensate supply pump, 22 ... each equipment, 23 ... feedback piping, 24 ... TO
C decomposition device, 25 hollow fiber membrane filter, 26 desalination tower, 27 bypass valve, 28 bypass pipe, 29 desalination tower supply pipe, 30
... ozone generator, 31 ... ozone injection pipe, 32 ... hydrogen gas outlet pipe, 33 ... condensing water circulation pump, 34 ... circulation pipe.

Claims (5)

[Claims] 1. A pure water producing apparatus for purifying raw water, a pure water supply pipe connected to the pure water producing apparatus, a condensate storage tank connected to a downstream side of the pure water supply pipe, A water quality maintaining device for a condensate storage tank, comprising: a TOC (total organic carbon) decomposing device having an ozone generator provided in a pipe. 2. The TOC decomposition apparatus includes a hollow fiber membrane filter connected to the pure water supply pipe, a desalination tower filled with an ion exchange resin connected to the hollow fiber membrane filter, and a desalination tower. An ozone generator connected to the outlet side of the ozone generator via a desalinated water supply pipe, and an ozone injection pipe connected to the ozone outlet side of the ozone generator and the pure water supply pipe on the inlet side of the condensate storage tank. The water quality maintaining device for a condensate storage tank according to claim 1, wherein: 3. A circulation pipe is provided through a circulation pump in a pure water supply pipe between the condensate storage tank and the pure water production apparatus and the TOC decomposition apparatus. The water quality maintaining device for the condensate storage tank described in the above. 4. The nuclear reactor according to claim 1, wherein said TOC decomposition apparatus is provided in a condensate purification system of a nuclear power plant.
The water quality maintaining device for the condensate storage tank described in the above. 5. The water quality maintaining device for a condensate storage tank according to claim 1, wherein the TOC decomposing device is connected to a heat source in a nuclear power plant and a hydrogen source when hydrogen is injected into feed water. .