JPH0464040B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas drive device, and more particularly to a gas drive device used in a hydrogen detection device in a cover gas of a fast breeder reactor.

Conventionally, in a steam generator for a fast breeder reactor, for example, as shown in FIG. 1, heat from sodium 1 in a secondary cooling system is transferred to water in a heat transfer tube 2 to generate steam. If the heat exchanger tube 2 in the steam generator 17 is damaged, the water inside the heat exchanger tube 2 will leak to the sodium side, causing a sodium-water reaction accident.
For this reason, it is necessary to detect water leakage at an early stage, and a hydrogen-in-sodium detection device 3 and a hydrogen-in-cover gas detection device 4 are provided. These detection devices 3 and 4 detect hydrogen generated by the reaction between sodium and water to discover water leakage due to damage to the heat transfer tube 2 or the like.

The former detection device 3 is mainly used to monitor water leakage from the heat transfer tube 2 in the sodium 1. The electromagnetic pump 5 samples some of the sodium in the main loop 6, guides it to the hydrogen meter 7, and collects the sodium. The structure is designed to detect an increase in the hydrogen concentration inside.

On the other hand, the latter detection device 4 mainly monitors water leakage in the cover gas 8 or from the heat exchanger tube 2 near the liquid level 9, and samples a part of the cover gas 8 to detect water leakage from the hydrogen meter 7. The structure is such that it detects an increase in the hydrogen concentration in the cover gas. The cover gas 8 in this detection device 4 is circulated by a pump 10. A large amount of sodium vapor and mist are mixed in the cover gas 8, and if this adheres to the movable parts of the pump 10 and solidifies, the pump 10 will suffer from "galling" or other malfunctions. Therefore, a vapor trap 11 is provided to avoid such failure of the pump 10.
This vapor trap 11 is located before the pump 10 and serves to remove sodium vapor and mist from the gas. This type of gas circulation system using the pump 10 has the disadvantage that the vapor trap 11 is required, resulting in a large-sized device. Also, Vapor Trap 1
If a failure occurs such as clogging of the pump 1 or "galling" of the movable part of the pump 10, maintenance of the device becomes difficult.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a gas drive device that is small in size and does not require maintenance.

In order to achieve the above object, a first invention of a gas drive device according to the present invention is provided in communication with a gas supply tank for adjusting cover gas pressure of a nuclear power plant, and at least one of liquid metal vapor and mist is provided. A gas drive device that circulates mixed gases and supplies them to predetermined equipment has a configuration in which a jet pump is installed in the gas circulation path, and a gas supply tank that supplies high-pressure gas is connected to the nozzle of the jet pump. .

A second invention is a gas drive that is provided in communication with a gas supply tank for adjusting the cover gas pressure of a nuclear power plant, circulates gas containing at least one of liquid metal vapor and mist, and supplies it to predetermined equipment. In the device, a jet pump is provided in the gas circulation path, and a pressurizing pump is installed at the nozzle of the jet pump to extract a part of the gas from the gas discharged from the jet pump and circulated, boost the pressure, and supply high-pressure gas to the nozzle. The configuration is such that they are connected.

Further, the third invention is provided in communication with a gas supply tank for adjusting cover gas pressure of a nuclear power plant,
In a gas drive device that circulates a gas containing at least one of liquid metal vapor and mist and supplies it to a predetermined device, a jet pump is installed in the gas circulation path, and a jet pump is provided with a jet pump that contains at least one of liquid metal vapor and mist. The structure is connected to an electromagnetic pump that takes out the liquid metal, increases the pressure, and supplies the high-pressure liquid metal to the nozzle.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 shows an embodiment of the first aspect of the present invention, in which an ejector 12 as a jet pump is used to drive the gas of the hydrogen detection device 7 in cover gas. The embodiment of FIG. 2 differs from that of FIG. 1 in that the pump 10 is replaced with an ejector 12, the vapor trap 11 that was necessary to protect the pump 10 is omitted, and the nozzle 13 of the ejector 12 is equipped with a nuclear power plant. High-pressure gas or liquid metal whose flow rate is controlled by a gas flow rate controller 20 is supplied from the gas supply tank 18 for adjusting the cover gas pressure.

The ejector 12 supplies a high pressure (approximately 2 kg/cm ² ) gas 16 from a high pressure fluid supply means to the nozzle 1 at a small flow rate.
3 and gives the momentum of the gas 14 coming out of the nozzle 13 to the cover gas 8 in the circulation system 15 to drive the cover gas 8 and guide it to the hydrogen meter 7.

The high-pressure fluid supply means is configured to supply high-pressure gas 16 necessary for the drive from a gas supply tank 18 that has been conventionally used for controlling the sodium liquid level in the steam generator 17. The flow rate of the gas blown from the nozzle 13 of the ejector 12 is the same as the cover gas 8 in the steam generator 17 during normal operation.
Since the change in volume is small (0.1%), even if the supply source of the high-pressure gas 16 is placed in the gas supply tank 18, it will not have any adverse effect on the conventional sodium liquid level control system. If the pressure of the cover gas 8 becomes high due to the injection gas 14, the gas release valve 1
9 is now operational.

The efficiency of the ejector used in this embodiment will be explained below.

FIG. 3 is an explanatory diagram showing the ejector 12 in an enlarged manner. In the figure, the ejector 12 converts the momentum of the gas 14 exiting the nozzle 13 into the main circulation system 15.
Mixing chamber 2 for uniformly mixing the cover gas 22 of
3, and an expansion chamber 24 that reduces the speed of the mixed gas 25 and converts the kinetic energy of the gas into pressure. As a result of the law of conservation of momentum being established in the mixing chamber 23 and the law of conservation of energy being established in the expansion chamber 24, the pressure ΔP that can be increased by the ejector is expressed by the following equation.

ΔP=1/2ρeVe ² +P ₀ −P ₂ =1/2ρ ₁ V ₁ ²・η ...(1) Here, η is the efficiency of the ejector, and η is
It is given by the following formula.

η=f[2-f{ρ ₂ /ρ ₁・(2f-1)/(1-f)
² K ² +1/ρ.(K ² ρ ₂ ² /ρ ₁ +2Kρ ₂ +ρ ₁ )}]...(2
) However, f: Ratio of cross-sectional area occupied by the nozzle to the cross-sectional area of the inlet of the mixing chamber K: Flow rate ratio {=V ₂ (1-f)/V ₁ f} V ₁ : Flow rate of gas exiting from the nozzle V ₂ : Cover gas flow rate at the mixing chamber inlet V ₀ : Gas flow rate at the mixing chamber outlet V. : Gas flow rate at the expansion chamber outlet ρ ₁ : Density of gas exiting from the nozzle ρ ₂ : Cover gas density at the mixing chamber inlet ρ ₀ : Mixing chamber outlet Gas density ρ at the expansion chamber outlet: Gas density P*: High pressure gas source pressure P ₂ : Cover gas pressure at the ejector inlet P ₁ : Gas pressure at the mixing chamber inlet P ₀ : Gas density at the mixing chamber outlet Pressure P.: Gas pressure at the ejector outlet (expansion chamber outlet) Figure 4 shows the ejector efficiency η using equation (2).
It is a characteristic diagram which shows the result of calculating. In the calculation,
Assuming the gas densities ρ ₂ and ρ ₀ , the cover gas (argon Ar, temperature =
^{The value of Ar at room temperature (50℃) is 1.5Kg/m 3 as} ρ ₁ . From the results shown in the figure, if the nozzle cross-sectional area ratio f is set to 0.1, for example, it is possible to drive gas four times the injected gas flow rate (K=4) with efficiency η=0.1. (☆ mark). On the other hand, the necessary pressure ΔP to be increased in the ejector is determined by the cover gas pressure loss in the main circulation system 15, and is determined by the pressure loss of the cover gas in the main circulation system 15.
Taking as an example the total length of piping = 20m and circulation flow rate = 5/mm), ΔP≒50Pa. If this pressure loss is compensated for by the ejector with η=0.1 mentioned above, the required exit gas flow velocity of the nozzle section will be 25 m/s. It is easy to obtain this level of gas flow velocity (~25 m/s),
It is sufficient if the pressure P ^* of the gas supply source 18 is 2 Kg/cm ² or more.

FIG. 5 is a configuration diagram showing an embodiment of the second invention of the present invention. This embodiment differs from the embodiment of FIG. 2 in that the high-pressure fluid (gas) supply means injected into the nozzle 13 is produced from the cover gas of the main circulation system 15. That is, the high-pressure fluid supply means uses the pump 10 to take out a part of the cover gas (1/5 flow rate in the previous example (Figure 4 ☆)) that exits the ejector 12 and returns to the steam generator 17, and increases the pressure. The configuration is such that the water is supplied to the nozzle 13.

In the case of such a gas driven device, the pump 10
In addition, a vapor trap 11 is required to protect this, but the flow rate of the cover gas passing through the gas injection system 21 is small, and the amount of sodium vapor and mist is also small. Therefore, the volumes of the pump 10 and vapor trap 11 can also be reduced. For example, in the previous example (Figure 4 ☆), if the flow rate ratio K = 4, the pump used in the conventional cover gas hydrogen detection device,
The volume of the vapor trap 11 should be 1/5. Therefore, the cover gas circulation system can be made 1/5 more compact than the conventional one. Further, malfunctions such as clogging of the vapor trap 11 and galling of the movable parts of the pump 10 are reduced, and maintenance of the apparatus can be reduced. In addition, in this embodiment, the high-pressure gas supply means necessary for the ejector is made from the cover gas 8, so there is no fear that the cover gas pressure in the steam generator 17 will increase due to the gas injected into the nozzle, and the liquid level control system There's no need to give it.

FIG. 6 is a configuration diagram showing an embodiment of the third aspect of the present invention. This embodiment differs from the embodiments shown in FIGS. 2 and 5 in that instead of injecting high pressure gas into the nozzle 13 of the ejector 12, liquid sodium 1 is injected to drive the cover gas 8. . That is, the high-pressure fluid supply means for supplying the liquid sodium necessary to drive the gas is
The liquid sodium 1 taken out from the steam generator 17 by the electromagnetic pump 5 is pressurized, then injected into the nozzle 13 and sprayed into the circulating cover gas to drive the gas.

According to such a gas drive device, the density ρ ₁ of the outlet fluid of the nozzle 13 becomes large, as expressed by equation (1), and therefore, there is an advantage that the pressure ΔP that can be increased by the ejector 12 can be increased. Note that the sodium after being sprayed returns to the steam generator 17 through the inner surface of the main circulation pipe 15 at the outlet.

In short, in this embodiment, the cover gas is driven by a jet pump having no moving parts, so the vapor trap can be omitted or downsized, and the cover gas circulation system can be made significantly more compact. Therefore, if this gas drive device is applied to, for example, a hydrogen detection device in a cover gas, the size of the entire device can be reduced. Further, problems (failures) such as clogging of the vapor trap and galling in the movable parts can be eliminated, and maintenance of the device can be eliminated or reduced.

Note that the gas drive device of the present invention is applicable not only to a device for detecting hydrogen in a cover gas, but also to a wide range of means for driving a cover gas of sodium equipment in general.

As described above, according to the first aspect of the present invention,
The high-pressure gas from the gas supply tank is supplied to the nozzle of the jet pump while controlling the flow rate, and the gas is circulated, resulting in a stable flow, making it possible to provide a gas drive device that is smaller and requires less maintenance. be. According to the second aspect of the present invention,
To provide a gas drive device in which the volume of the pump and vapor trap is reduced and maintenance is reduced, in order to supply high-pressure gas, which is a part of the exhaust gas of the jet pump, to a nozzle of the jet pump while controlling the flow rate. It has the effect of Further, according to the third aspect of the present invention, since the high pressure liquid metal obtained by boosting the pressure of a part of the liquid metal is supplied to the nozzle of the jet pump, the boost pressure of the jet pump can be increased, the jet pump can be made smaller, and it is easy to maintain the jet pump. This has the advantage that it is possible to provide a gas drive device with a reduced amount of gas.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the configuration of a conventional hydrogen detection device in cover gas of a steam generator, and FIG. 2 is a diagram for explaining the configuration of an embodiment of the first invention of the cover gas drive device according to the present invention. FIG. 3 is an explanatory diagram to explain the driving principle of the ejector used in the present invention, FIG. 4 is a characteristic diagram to explain the efficiency of the ejector in FIG. 3, and FIG. 5 is the same diagram. Second
FIG. 6 is a block diagram showing an embodiment of the invention. FIG. 6 is a block diagram showing an embodiment of the third invention. 1... Sodium, 2... Heat exchanger tube, 3... Hydrogen detection device in sodium, 4... Hydrogen detection device in cover gas, 5... Electromagnetic pump, 6... Main loop,
7... Hydrogen meter, 8... Cover gas, 9... Sodium liquid level, 10... Pump, 11... Vapor trap, 12... Ejector, 13... Nozzle, 1
4...Gas coming out of the nozzle, 15...Cover gas circulation system, 16...High pressure injection gas, 17...Steam generator, 18...Gas supply tank, 19...Gas release valve, 20...Gas flow rate control container, 21... gas injection system, 22... cover gas in the main circulation system, 23...
...mixing chamber, 24...expansion chamber, 25...mixing chamber outlet gas.

Claims (1)

[Scope of Claims] 1. A gas that is provided in communication with a gas supply tank for adjusting cover gas pressure in a nuclear power plant, circulates gas containing at least one of liquid metal vapor and mist, and supplies it to predetermined equipment. A gas drive device, characterized in that a jet pump is provided in the gas circulation path, and the gas supply tank for supplying high-pressure gas is connected to a nozzle of the jet pump. 2. In a gas drive device that is installed in communication with a gas supply tank for adjusting cover gas pressure in a nuclear power plant and that circulates gas containing at least one of liquid metal vapor and mist and supplies the gas to predetermined equipment. A jet pump is provided in the circulation path of the jet pump, and a pressurizing pump is provided at a nozzle of the jet pump to take out a part of the gas discharged from the jet pump and circulated, and to boost the pressure and supply high-pressure gas to the nozzle. A gas drive device characterized by being connected. 3. A gas drive device that is installed in communication with a gas supply tank for adjusting cover gas pressure in a nuclear power plant, and that circulates gas containing at least one of liquid metal vapor and mist and supplies it to predetermined equipment. A jet pump is provided in the circulation path of the jet pump, and an electromagnetic pump is connected to the nozzle of the jet pump to extract a part of the liquid metal from the liquid metal, raise the pressure, and supply high-pressure liquid metal to the nozzle. Gas driven equipment.