JPH028200B2 - - Google Patents

Description

[Detailed Description of the Invention] Conventionally, tanks for storing low-temperature liquids have been constructed with a water-stop wall made of concrete on the outside of the tank body for storing low-temperature liquids, and in the event that the liquid inside the tank body leaks, it can be stopped. There is a type that allows the water to collect inside the wall, but recently, the water stop wall of the above type is moved closer to the tank body to form the outer tank side wall, and a seal plate is installed inside this outer tank side wall to make the water tight. A type of concrete cryogenic tank that maintains the temperature is being considered.

The present invention relates to such a state-of-the-art concrete-type cryogenic tank that, when the inner tank is destroyed, maintains the pressure balance between the inner and outer tanks to prevent further destruction of the inner tank. .

As shown in FIG. 1, the concrete type low-temperature tank described above has an outer tank concrete 2 built on a foundation concrete 1 to serve as an outer tank side plate, and an inner tank inside the outer tank concrete 2. An inner tank 3 consisting of a side plate 4, an inner tank bottom plate 5, and an inner tank roof plate 6 is installed, and inside the outer tank concrete 2 is a cold insulation material made of glass wool, hard polyurethane foam, etc., layered to the required thickness. 7 is stretched over the entire circumference, a cold insulating material 8 is provided on the upper surface of the foundation concrete 1, and a side membrane 10 is placed on the upper surface of the cold insulating material 8 located inside the cold insulating material 7 and outside the inner tank 3. A seal plate 9 consisting of a bottom membrane 11 and a bottom membrane 11 are attached, and the peripheral part of an outer tank bottom plate 12 placed between the inner tank side plate 5 of the inner tank 3 and the cold insulation material 8 is overlapped with the bottom membrane 11 of the seal plate 9. In the event that liquid leaks from the inner tank 3, a seal plate 9 is used to maintain liquid tightness. 13
1 is leveled concrete poured between the inner tank bottom plate 5 and the outer tank bottom plate 12, 14 is an outer tank roof plate, 15 is a cold insulation material, and 16 is an inner tank anchor.

In such a low-temperature tank consisting of an inner tank and an outer tank, with a cold insulating material provided on the outer tank side, if the side plate 4 of the inner tank 3 breaks and the low-temperature fluid in the inner tank 3 leaks into the outer tank, Although the pressure inside the inner tank 3 decreases, the pressure between the outer tank and the inner tank increases, so there is a risk that the inner tank roof board 6 will further break due to the differential pressure between the inside and outside of the inner tank 3. be.

The present invention was made in an attempt to prevent further destruction of the above-mentioned inner tank, and is a double-structured structure in which a space is provided between the inner tank and the outer tank, and leaked liquid is sealed within the space. In the low-temperature tank, a device is installed to detect the gas, gas pressure, and liquid level in the space, and a differential pressure gauge is installed to measure the differential pressure between the space and the inner tank. This is characterized in that the space and the inner tank are communicated with each other through a flow path that can be opened and closed in response to a signal from, etc.

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 2, in a tank constructed in the same manner as in FIG. The supply pipe 19 is connected to the reliquefaction equipment 20, and normally, after the gas in the inner tank 3 is sent to the reliquefaction equipment 20 through the discharge pipe 17, the liquid from the reliquefaction equipment 20 is connected to the reliquefaction equipment 20. 18 into the inner tank 3, and the gas is returned through the supply pipe 19 as it is to control the pressure inside the inner tank 3. The tank of the present invention further includes a gas pressure detector 21 for detecting the gas pressure in the inner tank 3, and a gas pressure detector 21 for detecting the gas pressure in the space S between the inner tank 3 and the seal plate 9 on the inner surface of the outer tank. A pressure detector 22, a gas detector 23 for detecting gas in the space S, and a liquid level gauge 36 are provided, and the difference between the gas pressure in the space S and the gas pressure in the inner tank 3 is measured. A differential pressure gauge 24 was provided and communicated with the space S in order to guide the gas in the space S into the inner tank 3 and balance the pressures in the inner tank 3 and between the inner and outer tanks (space S). A gas exhaust pipe 25 is connected to the gas exhaust pipe 17 so that the gas in the space S is supplied into the inner tank 3.

Further, a branch pipe 26 is connected in the middle of the downstream side of the connection point between the gas exhaust pipes 17 and 25, and the flare stack 27 is communicated with the branch pipe 26, so that the gas pressure in the space S is high and the inside Gas discharge pipes 17 and 2 are provided so that in case of an emergency when the gas cannot escape through the communication between the tank 3 and the space S, the gas can escape to the outside through the flare stack 27, and so that the above-mentioned system operates properly.
5. In the middle of the branch pipe 26, install solenoid valves 28, 29,
30, 31, and solenoid valves 28, 29, 31
has a pressure detector 21, a pressure detector 22, a gas detector 23 and a differential pressure gauge 24,
In addition to the normal operation in which the liquid level gauges 36 are connected and the gas in the inner tank is returned as a liquid by opening and closing each solenoid valve, there is also an operation in which the gas in the space S is introduced into the inner tank 3. be able to do so.

32 is a heat exchanger, 33 and 34 are electromagnetic valves, 35 is a bottom heater, and 37 is a safety valve.

With the above configuration, normally the valves 28, 2
9 is opened to guide the gas in the inner tank 3 to the reliquefaction equipment 20, where it is liquefied and sent to the inner tank 3 via the liquid supply pipe 18.
The pressure inside the inner tank 3 is controlled. During this normal operation, the inner tank 3
When the internal pressure becomes abnormally high, the safety valve 37 is first activated, and if the increase in pressure cannot be followed, a signal from the pressure detector 21 causes the increased pressure to be released through the flare stack 27. This allows safe operation of the tank during normal operation.

During the above normal operation, if the inner tank side plate 4 of the inner tank 3 breaks for some reason and the stored liquid begins to leak, the leaked liquid is sealed by the seal plate 9 of the outer tank and stored in the space S. , while the pressure in the inner tank 3 decreases, the pressure in the space S increases, and the pressure in the inner tank 3 decreases.
It becomes a state where external pressure acts on the If such a pressure difference is left as it is, there is a risk that the inner tank roof plate 6 will not be able to withstand the external pressure and will be destroyed. Therefore, in the present invention, the pressure and gas in the space S are detected by the respective detectors 22 and 23, and the differential pressure between the pressure in the inner tank 3 and the pressure in the space S is detected by the differential pressure gauge 24. When the pressure in the space S becomes higher than the pressure in the inner tank 3, the solenoid valve 30 is opened by the signals from each detector 22, 23 and the differential pressure gauge 24, and the inner tank 3 and the space are separated. S is communicated with. Therefore, the operation is performed so that the gas in the space S is guided to the reliquefaction equipment 20 via the discharge pipes 25 and 17, and further returned to the inner tank 3. As a result, the pressure in the space S and the pressure in the inner tank 3 are balanced, and destruction of the inner tank roof plate 6 can be prevented.

If a pressure difference occurs that is insufficient to prevent destruction of the inner tank roof plate 6 in the operation in which the inner tank 3 and the space S are communicated and the pressure in the space S is returned to the inner tank 3, the solenoid valve 31 is opened to release the pressure in the space S to the outside via the flare stack 27. Thereby, even in an emergency, the external pressure acting on the inner tank roof plate 6 can be immediately released, and the roof plate 6 can be prevented from being destroyed.

When the pressures in the inner tank 3 and the space S become balanced, the differential pressure disappears and the solenoid valve 30 is closed.
Switch to normal operation.

Therefore, in the present invention, the solenoid valves 30 and 31 are set to open and close at different times depending on the values of the differential pressure gauge 24 and the detectors 22 and 23.

In addition, during normal operation of the tank, if the gas pressure in the inner tank 3 decreases, the pressure detector 21
This value can be used to detect the solenoid valve 3 in the middle of the bypass pipe that has the heat exchanger 32.
3 and 34, the stored liquid can be vaporized and returned into the inner tank 3, and the pressure inside the inner tank 3 can be controlled.

Furthermore, the present invention is not limited to the configuration shown in the drawings; for example, the outer tank may be made of metal instead of the concrete type, and other aspects do not depart from the gist of the present invention. Of course, changes can be made within the scope.

As described above, according to the double structure low temperature tank of the present invention, the space and the inner tank are separated by the gas in the space between the inner tank and the outer tank, the gas pressure, the pressure difference between the gas pressure in the inner tank, etc. The inner tank is connected to allow gas to circulate, and to prevent the pressure in the space from becoming higher than that in the inner tank due to liquid leakage. This has the excellent effect of preventing the tank roof plate from being destroyed, which is likely to occur next time a liquid leaks.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a concrete type low temperature tank, which is the object of the present invention, and FIG. 2 is a schematic diagram of the double-structured low temperature tank of the present invention. 2... Outer tank concrete, 3... Inner tank, 7, 8... Cold insulation material, 9... Seal plate, 17, 25... Gas discharge pipe,
18...Liquid supply pipe, 19...Gas supply pipe, 20...Reliquefaction equipment, 21, 22...Gas pressure detector, 23...Gas detector, 24...Differential pressure gauge, 27...Flare stack.

Claims (1)

[Claims] 1. In a double-walled cryogenic tank that has a space between the inner tank and the outer tank so that leaked liquid can be stored in the space, a reliquefaction device is connected to the gas exhaust pipe that communicates with the inner tank, and the reliquefaction equipment is A liquid supply pipe that introduces liquid into the inner tank of the liquefier and a gas supply pipe that introduces gas into the inner tank are connected to a gas pressure detector that detects the gas pressure in the space, and a gas pressure detector that detects the gas in the space. A gas detector, a liquid level gauge, and a differential pressure gauge for detecting the pressure difference in the space and the inner tank are provided, and the solenoid valve is operable to open and close based on the signals of the gas pressure detector, the liquid level gauge, and the differential pressure gauge. A double-structure low-temperature tank characterized in that the reliquefier and the space are connected through a gas discharge pipe.