JPS62150198A - Hydrogen-gas injection-recovery device for boiling water type reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention is a boiling water reactor, in which hydrogen is injected into the reactor in order to improve the water quality of the reactor water, and the surplus of the injected hydrogen is separated and This invention relates to hydrogen gas injection and recovery equipment for boiling water reactors that is recovered and reused.

[Technical background of the invention and its problems] In a boiling water reactor (1J, referred to as BWR), the temperature of the coolant in the reactor pressure vessel rises due to the heat of nuclear reaction in the reactor core as it flows upward into the reactor core. This results in a two-phase flow state of water and steam.

The coolant in this two-phase flow state is introduced into an air-hydraulic M unit installed above the reactor core, where it is separated into water and air. The separated steam is transferred to the turbine system via the main steam pipe connected to the reactor pressure vessel and used for power generation.

As described above, steam is generated in the reactor core, but in addition to this steam, oxygen gas (02)J> and hydrogen gas (H2) are also generated. Of these, oxygen gas has an undesirable effect on equipment in the reactor, so conventionally hydrogen gas has been injected into the reactor water to improve the water quality of the reactor water.

At this time, the gas body resulting from injection of hydrogen gas, etc. will eventually be released into the atmosphere as waste gas, but the following operations are taken to prevent explosions due to hydrogen gas during the release process. In other words, waste gas is introduced into a gaseous waste treatment system installed immediately after the steam turbine, and through a catalytic reaction (H
20) and then discharged. In this case, hydrogen and oxygen must be in a chemically equivalent ratio in the system, but as mentioned above, when hydrogen gas is injected to improve water quality, the presence of excess hydrogen gas In order to achieve a virtually equivalent ratio, it is necessary to inject an appropriate amount of oxygen gas from outside the system. Conventionally, large amounts of hydrogen gas had to be injected to improve water quality, and large amounts of oxygen gas had to be injected for subsequent gaseous waste treatment. There is a problem in that not only the injection equipment but also the injection layer is large, which increases the cost, and an improvement has been required.

[Purpose of the Invention] The present invention has been made based on the above points, and its purpose is to eliminate the need to inject oxygen gas into waste gas, reduce the amount of hydrogen gas injected, and reduce equipment costs and operation costs. Hydrogen gas injection and
The objective is to provide a collection device.

[Summary of the invention] That is, the hydrogen gas injection and
The recovery device consists of a reactor pressure vessel that houses coolant and the reactor core, a steam system that supplies the steam generated in the reactor pressure vessel to a steam turbine for power generation, and a steam system that supplies the steam that drives the steam turbine to the reactor pressure vessel. In a boiling water reactor equipped with a condenser that is introduced into the water supply system to condense and liquefy it into condensate, and a water supply system that purifies the condensate and returns it to the reactor pressure vessel, hydrogen gas is introduced into the water supply system. and a hydrogen gas separation/recovery device that introduces waste gas from the condenser, continuously separates and recovers hydrogen gas from the waste gas, and supplies the hydrogen gas to the hydrogen gas injection device. It is characterized by having the following.

In other words, in order to improve the water quality of the reactor water, hydrogen gas is injected into the water supply system using a hydrogen gas injection device, and excess hydrogen gas is separated and recovered from the waste gas from the condenser and then fed to the hydrogen gas injection device. It is something that is supplied and reused.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. Figure 1 shows the schematic configuration of the BWR and the configuration of the hydrogen gas injection/recovery device.
1 is a reactor pressure vessel.

A coolant 2 and a reactor core 3 are housed within a reactor pressure vessel 1 . This core 3 is composed of a plurality of fuel assemblies, control rods, etc. (not shown).

Reference numeral 4 in the figure is a control rod drive mechanism that controls the insertion of the control rods into the reactor core. When the coolant 2 moves up the reactor core 3, its temperature increases due to the heat of nuclear reaction in the reactor core 3, and the coolant 2 enters a two-phase flow state of water and steam. The coolant 2 in a two-phase flow state is introduced into a steam-water separator installed above the reactor core 3 and separated into steam and water. The separated internal steam is introduced into a steam dryer installed above the steam separator and dried to produce dry steam. This dry steam is transferred to a steam turbine 6 via a main steam pipe 5 connected to the reactor pressure vessel 1. The steam that has worked in the steam turbine 6 is introduced into the condenser 7.

The steam introduced into the condenser 7 is pseudo-condensed and liquefied there to become condensate. The condensate is introduced into the condensate purifier 8, purified, and supplied into the reactor pressure vessel 1 via the water supply pump 9 and the water supply piping 10. On the other hand, the water separated by the steam separator flows down to the downcomer section and is supplied below the reactor core 3 in a state where it is mixed with the feed water. The same cycle is repeated thereafter.

Reference numeral 11 in the figure indicates a recirculation system. This recirculation system 11 is located on the outer periphery of the reactor core 3, and includes a plurality of jet pumps 12 installed at equal intervals in the circumferential direction inside the reactor pressure vessel 1, and a recirculation pump 13 installed outside the reactor pressure vessel 1. and a recirculation system piping 14 disposed between the two. This recirculation system 11 forces the coolant 2 to circulate through the core 3 .

A BWR having such a configuration is equipped with a hydrogen gas injection/recovery device. The configuration of this hydrogen gas injection/recovery device will be explained below. The hydrogen gas injection/recovery device is composed of a hydrogen gas injection device A and a hydrogen gas separation/recovery device B. For convenience of explanation, hydrogen gas separation/recovery equipment B
I will explain from.

A waste gas processing pipe 15 is connected to the condenser 7, and the gas separated in the condenser 7 is passed along with the in-leak air in the condenser 7 as waste gas to the waste gas processing pipe 1.
5 into the gas extractor 16. A recombiner 17, a condenser 18, a gas compressor 19, and a hydrogen gas separation column device 20 are inserted in this order on the downstream side of the gas extractor 16 in the waste gas treatment pipe 15. The hydrogen gas separation column device 20 is composed of two hydrogen gas separation columns 21A and 21B connected in parallel. In addition, hydrogen gas separation tower device 2
Switching valves 22A, 22B and three-way switching valves 23A, 23B are inserted on the inlet side and outlet side of 0, respectively.

The hydrogen gas separated by the hydrogen gas separation column device A is introduced into the hydrogen gas pressure unit 25 via the hydrogen gas injection pipe 24 of the hydrogen gas injection device A. This hydrogen gas compressor 2
The hydrogen gas compressed in step 5 is introduced into a pressure accumulator 26. On the other hand, waste gas other than hydrogen gas separated by the hydrogen gas separation column ff120 is discharged into the atmosphere via the stack 27.

An auxiliary hydrogen gas storage device 28 is provided in the hydrogen gas injection pipe 24.
are branched and connected via a flow rate control valve 29. This auxiliary hydrogen gas storage device 28 is used at the initial stage of reactor operation, and is also used to replenish hydrogen gas in the system when it becomes insufficient. In addition, code 3 in the figure
1 is a hydrogen gas injection valve.

The operation will be explained based on the above configuration, and the configuration will be roughly explained in detail. First, a mixed gas consisting of hydrogen gas, oxygen gas, and radioactive rare gas from the reactor pressure vessel 1 and in-leak air (oxygen gas and nitrogen gas) from the condenser 7 is extracted as waste gas through the waste gas processing pipe 15. is introduced into the container 16. The waste gas that has passed through the gas extractor 16 is introduced into the recombiner 17. In this recombiner 17, oxygen gas is removed in the form of H2O. At this time, since the nuclear reactor is operated with hydrogen gas injection, the amount of hydrogen gas in the waste gas is significantly larger than that of oxygen gas, and the hydrogen gas remains even after being removed in the form of H20. This remaining hydrogen gas is to be separated by the hydrogen gas separation column device 11. In other words, the waste gas containing hydrogen gas is sent to the condenser 1.
8, where water is removed. The waste gas from which moisture has been removed is introduced into hydrogen gas separation column device 2. Here, the structure of the hydrogen gas separation column device 2o will be explained in detail. The hydrogen gas separation column device 2-Ω is composed of two hydrogen gas separation columns 21A and 21B as described above. Respective hydrogen gas separation towers 21A and 2
A hydrogen storage alloy 30 is stored in 1B. This hydrogen storage alloy 30 is made of a Ca-Ni-Mn-Al alloy, and undergoes a reaction as shown in the following reversible chemical reaction formula.

M+H24MHx±ΔQ where M: Hydrogen storage alloy MHx: Metal hydride ΔQ: Heat of reaction As shown in this equation, the hydrogen storage alloy 30 has the property of selectively occluding hydrogen gas in the form of metal and metal hydrides. ing. That is, when the hydrogen storage alloy 30 is kept at a low temperature, it absorbs hydrogen gas while generating heat, and conversely, when the hydrogen storage alloy 30 reaches a high temperature, it releases hydrogen gas while absorbing heat. Further, each of the hydrogen gas separation columns 21A and 21B is equipped with a heat exchanger (not shown), so that the temperature of the hydrogen storage alloy 30 can be adjusted. Further, in the hydrogen gas separation column apparatus unit, when one hydrogen gas separation column 21A is separating and storing hydrogen gas, the other hydrogen gas separation column 21B is releasing hydrogen gas or is on standby. This is the switching valve 22A, 22
B, and the relationship with the three-way switching valves 23A and 23B. First, the hydrogen gas separation column 21A stores hydrogen gas,
When the hydrogen gas separation tower 21B is discharging gas, the switching valve 22A is open and the switching valve 22B is closed, as shown in FIG. On the other hand, the three-way switching valve 23A is open on the stack 27 side and closed on the hydrogen gas injection pipe 24 side, and the three-way switching valve 23B is closed on the stack 27 side and open on the hydrogen gas injection pipe 24 side. Therefore, hydrogen gas is stored in the hydrogen storage alloy 30 in the hydrogen gas separation tower 2iA,
Waste gases other than hydrogen gas are discharged into the atmosphere via the stack 27. On the other hand, the hydrogen gas separation column 21B side releases the stored hydrogen gas, and the released hydrogen gas is released into the hydrogen gas injection pipe 24 via the three-way switching valve 23B. The following is the switching valve 22A.

22B1 and the three-way switching valves 23A and 23B, and by heating or cooling the hydrogen storage alloy 30 with each heat exchanger, hydrogen storage or release is performed alternately. This will be explained with reference to the operation cycle diagrams shown in FIGS. 2 and 3. First, the hydrogen gas separation tower 21A enters the hydrogen gas storage process while cooling the hydrogen storage alloy 30. At the final stage of the hydrogen storage process, the hydrogen gas separation column 21
Cooling of the hydrogen storage alloy 30 is started on the B side, and the occlusion process starts at the same time as the occlusion stops on the hydrogen gas separation column 2iA side. At this time, the hydrogen storage alloy 30 is heated on the hydrogen gas separation tower 21A side, and the release process is started.

Thereafter, occlusion and release are performed continuously and alternately in the same manner, as shown in FIG. 3. In addition, the hydrogen gas separation tower 2
Switching between hydrogen gas separation towers 21A and 21B is performed based on a signal from a hydrogen gas detector (not shown) installed on the outlet side of each of these hydrogen gas separation towers 21A and 21B.

Hydrogen gas released from the hydrogen gas storage alloy 30 is introduced into the hydrogen gas compressor 25, compressed, and stored in the pressure accumulator 26. Thereafter, the water is injected into the reactor pressure vessel 1 via the water supply pump 9.

At this time, the opening degree of the hydrogen gas injection valve 31 is automatically adjusted by either or both signals from the reactor water oxygen/hydrogen concentration meter and the feed water flow meter, and the hydrogen gas flow rate is controlled. By repeating the above operations, hydrogen gas is continuously injected and recovered, and waste gas is discharged.

According to this embodiment, the following effects can be achieved. In other words, whereas in the past, excess hydrogen was injected and necessary oxygen was required to treat the surplus hydrogen as a result of this excessive injection, in this example, the excess hydrogen gas was Since hydrogen gas can be recovered and reused by the hydrogen storage alloy 30 of the separation column device 20, hydrogen gas can be used effectively and there is no need to inject oxygen gas as in the conventional case. Therefore, the equipment is simplified and costs are significantly reduced.

Considering this in an 800 MWe class BWR, the oxygen concentration in the reactor water is maintained at 20 ppb or less, and the
Hydrogen gas separation column 2 containing hydrogen storage alloy 30 of g/column
When 1A and 21B were used, hydrogen gas with a purity of 99.9% or more could be recovered at a recovery rate of about 96%. Here, the reason why the recovery rate does not reach 100 is due to the amount consumed in the bonding reaction with the oxygen gas in the in-leak air of the condenser 7.
This is because some of the hydrogen gas flows out to the stack 27 side during the switching operation between the hydrogen gas separation columns 21A and 218. This shortage is replenished from the auxiliary hydrogen storage device 28.

Furthermore, when the consumption amounts of hydrogen gas and oxygen gas are compared between the present example and the conventional case, the results are shown in Table 1 below.

Table 1 As shown in Table 1, in the case of this example, the consumption of hydrogen gas is significantly reduced compared to the conventional case, and as oxygen gas is not used at all, the consumption The quantity is zero. Therefore, operating costs are significantly reduced.

The present invention is not limited to the above-mentioned embodiments, and the hydrogen storage alloy 30 may include <La-Ni>, (Ti-Fe), (Ti-
It is possible to use hydrogen storage alloys such as Mn)-based hydrogen storage alloys, and by appropriately changing the pressure of injection into the hydrogen gas separation column and the heat exchange temperature by the built-in heat exchanger depending on the characteristics of each of the above alloys, similar results can be obtained. It can be effective.

In addition, the number of hydrogen gas separation columns was 2 in the above embodiment.
Although the case of towers has been described, the invention is not limited to this, and three or more towers may be used.

[Effects of the Invention] As detailed above, according to the hydrogen gas injection and recovery device for a boiling water reactor according to the present invention, surplus hydrogen gas can be recovered and used, and hydrogen gas can be used effectively. hydrogen gas consumption can be significantly reduced. Further, there is no need to use oxygen gas. Therefore, equipment can be greatly simplified, and costs can be reduced.
In particular, operating costs can be reduced.

[Brief explanation of drawings]

1 to 3 do not show one embodiment of the present invention;
The figure shows the configuration of the boiling water reactor and the hydrogen gas injection/recovery device, and FIGS. 2 and 3 are diagrams showing the operation cycle of the hydrogen injection/recovery device. DESCRIPTION OF SYMBOLS 1... Reactor pressure vessel, 2... Coolant, 3... Reactor core, 5... Main steam piping, 6... Steam turbine, 7...
...Condenser, 8...Condensate purifier, 9...Water supply pump, 10...Water supply piping, A...Hydrogen gas injection device, B
...Hydrogen gas separation/recovery equipment.

Claims (3)

[Claims] (1) A reactor pressure vessel containing coolant and a reactor core;
A steam system that supplies the steam generated in the reactor pressure vessel to a steam turbine for power generation, and a condenser that introduces the steam that drives the steam turbine and condenses and liquefies it into condensate. In a boiling water nuclear reactor equipped with a water supply system that purifies the condensate and returns it to the reactor pressure vessel, a hydrogen gas injection device that injects hydrogen gas into the water supply system, and waste gas from the condenser. Hydrogen gas for a boiling water reactor, characterized in that it is equipped with a hydrogen gas separation/recovery device that introduces hydrogen gas, continuously separates and recovers hydrogen gas from the waste gas, and supplies the hydrogen gas to the hydrogen gas injection device. Injection/recovery equipment. (2) The above hydrogen gas separation/recovery device includes a hydrogen gas separation tower device comprising a plurality of hydrogen gas separation towers each having a hydrogen storage alloy inside that stores hydrogen gas at low temperatures and releases hydrogen gas at high temperatures. A hydrogen gas injection/recovery device for a boiling water reactor according to claim 1, wherein the hydrogen gas injection/recovery device is installed in a boiling water reactor. (3) The hydrogen gas injection/recovery device for a boiling water reactor according to claim 1, wherein the hydrogen gas injection device includes an auxiliary hydrogen gas injection device.