JP2002131114A - Liquid level detector for cryogenic liquid storage containers - Google Patents

Abstract

(57) [Problem] To provide a liquid level detection device in a low-temperature liquid storage container that can stably detect a liquid level over a long period of time. An insulated storage container storing a low-temperature liquid.
(1) The liquid level gauge protruding and arranged inside is constituted by a capacitance type liquid level gauge (2), and the gas flow holes (12) of the capacitance type liquid level meter (2) are Open the part (14).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level detecting device for detecting a liquid level in an insulated storage container storing a low-temperature liquid such as a liquefied gas by a capacitance type liquid level meter.

[0002]

2. Description of the Related Art As is well known, in a capacitance type liquid level meter, an electrode rod is inserted into a ground tube, and a liquid storage hole located outside the ground tube is provided through a liquid flow hole formed at a lower end of the ground tube. The inside of the container and the inside of the ground tube are communicated with each other, and the change in capacitance caused by the amount of liquid entering the gap formed between the electrode rod and the wall surface of the ground tube is detected to detect the liquid level. I have. In this case, a gas vent hole is formed in the upper portion of the ground tube so that the liquid can smoothly enter and exit the gap formed between the electrode rod and the wall surface of the ground tube.

[0003] When an insulated container storing a low-temperature liquid such as liquefied gas has a structure in which an inner tank and an outer tank are connected by a neck tube, the temperature of the gas phase in the container depends on the liquid level. Even though the temperature is stable at the liquid temperature, the temperature at the neck tube portion has a temperature gradient from the upper end room temperature to the lower end liquid temperature. Conventionally, when a capacitance-type liquid level gauge is mounted to detect the liquid level in such an insulated container, the vent hole of the capacitance-type liquid level gauge is located in a portion having a temperature gradient. Was.

[0004]

When the gas vent hole is located in the neck tube portion, the temperature of the ground tube near the gas vent hole is in the middle of the temperature gradient. The moisture condensed still has fluidity, and the condensed water enters the ground tube through the gas vent hole, and the electrode and the ground tube conduct, and the exact capacitance (liquid level) is measured. There was a problem that you can not. In addition, even in an insulated container for storing a low-temperature liquid without a neck tube, the ground tube portion exposed outside the container is cooled by the low-temperature liquid,
Due to the temperature difference from the outside air, moisture in the outside air may condense on the ground tube, and the condensed water may flow down the ground tube and enter the ground tube through the gas vent hole.

An object of the present invention is to provide a liquid level detecting apparatus in a low-temperature liquid storage container capable of stably detecting the liquid level over a long period of time, paying attention to such points.

[0006]

According to the first aspect of the present invention, a liquid level gauge is constituted by a capacitance type liquid level meter. It is characterized in that the gas flow hole is opened to the gas phase inside the container.

According to the second aspect of the present invention, the capacitance-type liquid level gauge protrudes into the heat-insulating container while penetrating the lid disposed so as to close the upper opening of the heat-insulating container.
It is characterized in that the liquid level gauge insertion port is hermetically sealed and a gas discharge tube is arranged so as to communicate with the gas phase part in the storage container.

[0008]

According to the present invention, the liquid level gauge is constituted by a capacitance type liquid level meter, and the gas flow hole of the capacitance type liquid level meter is opened to the gas phase inside the container. Therefore, since the gas flow holes are exposed to the low temperature liquid temperature, even if the dew condensation water adheres to the outer wall of the gland tube, it freezes up to the gas flow hole part and the dew water enters the gland tube. No more infiltration.

In addition, since the mounting portion of the capacitance type liquid level gauge attached to the lid for closing the opening of the heat insulating container is hermetically sealed, the gas in the gas phase in the heat insulating container is liquid level. The condensed water flows down into the gland tube from the gas flow hole because the condensed water is no longer led out from the mounting hole and the condensed water is cooled by the derived low-temperature gas and the condensed water does not condense. No intrusion.

[0010]

FIG. 1 is a schematic diagram showing an embodiment of the present invention. In the figure, reference numeral (1) denotes a heat insulating container for storing low-temperature liquid such as liquefied gas, and (2) denotes a capacitance type liquid level gauge. The insulated container (1) is formed by connecting the inner tank (3) and the outer tank (4) with a neck tube (5), and narrowing the upper opening.
The narrowed opening (6) is closed by a lid (7).

The capacitance type liquid level meter (2) has a detecting unit
(8) penetrates through the lid (7) and protrudes into the inner tank (3). The detection unit (8) has a ground tube (9) and an electrode rod (10) inserted through the ground tube (9) in a non-contact manner, and the ground tube (9) has a liquid at its lower end. A gas flow hole (12) is provided through the flow hole (11), and a gas flow hole (12) is provided through the middle part. Then, the liquid in the tank flows into the gap (13) between the ground tube (9) and the electrode rod (10) from the liquid circulation hole (11), and the gas in the gap (13) flows through the gas circulation hole ( From 12), it flows out to the gas phase part (14) in the tank. Therefore, the liquid level position in the gap (13) accurately reflects the liquid level position in the container.

In such a liquid level detecting device in the storage container, the present invention provides the gas flow hole (12) in the gas phase (14) below the inner tank side end of the neck pipe (5). It is open.
Thus, when the gas flow hole (12) is opened to the gas phase part (14) on the lower side also near the neck pipe (5), the gas flow hole (12) is maintained at the same temperature as the low-temperature liquid. Since the gas is opened in the gas phase portion (14) filled with the vaporized gas atmosphere of the low-temperature liquid, impurity gas and moisture do not condense on the peripheral surface of the ground tube (9). It does not enter the gap (13) between the ground tube (9) and the electrode rod (10) through the flow hole (12).

Reference numeral (15) in the figure denotes a gas discharge pipe led out of the lid (7), and the heat insulating container (1) is an open container by the discharge pipe (15).

FIG. 2 is a schematic diagram showing a different embodiment. In this embodiment, an insulated container (1) for storing low-temperature liquids
Is formed in a cylindrical shape with the inner and outer tanks (3) and (4) connected at the upper end, and the upper opening (6) of the heat insulating container (1) is closed with a lid (7).

In this embodiment, a capacitance type liquid level gauge (2)
Airtight joining structure such as flange joining and upsetting to the lid (7)
It is fixed by using (16), and the gas discharge pipe (15) is led out from a place away from the liquid level gauge mounting part. Also in this case, the gas flow hole (12) provided in the ground tube (9) of the capacitance type liquid level gauge (2) is opened to the gas phase part (14) in the inner tank (3). .

As described above, when the level gauge mounting portion is sealed, the low-temperature gas present in the gas phase portion in the heat insulating container (1) is released from the level gauge mounting portion, and the vicinity of the level gauge is released. Condensation on the surface of the liquid level gauge due to cooling can be prevented, and the condensed water flows down the ground tube (9) and the gap between the gas tube (12) and the ground tube (9) and the electrode rod (10). It can be prevented from entering.

[0017]

According to the present invention, the liquid level gauge is constituted by a capacitance type liquid level meter, and the gas flow hole of this capacitance type liquid level meter is opened to the gas phase inside the container. Therefore, since the gas flow holes are exposed to the high-purity gas at the low-temperature liquid temperature, the dew condensation does not occur and the dew water does not enter the ground tube. Thus, the liquid level position can be detected without malfunction.

Further, when the mounting portion of the capacitance type liquid level gauge attached to the lid for closing the opening of the heat insulating container is hermetically sealed, the gas in the gas phase in the heat insulating container is discharged. It is no longer led out from the mounting hole, and the area around the ground tube that is exposed to the outside is cooled by the derived low-temperature gas and no condensation forms, so the dew condensation water flows down and enters the ground tube from the gas flow hole part Without
Liquid level detection can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a different embodiment of the present invention.

[Explanation of symbols]

1. Insulated storage container 2. Liquid level meter (capacitance type liquid level meter), 3.
... Inner tank, 4 ... Outer tank, 5 ... Neck tube, 6 ... Opening of the upper surface of the heat insulating storage container, 7 ... Lid, 12 ... Gas flow hole, 14 ... Gas phase part
15 ... Gas discharge tube.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Wataru Saiga, Inventor, 4-5-1 Katsubabe, Moriyama-shi, Shiga Prefecture Inside Iwatani Gas Co., Ltd. (72) Masato Adachi 4-5-1, Katsurbe, Moriyama-shi, Shiga Prefecture Iwatani Within Gas Co., Ltd. (72) Inventor Etsuji Kawaguchi 4-5-1 Katsube, Moriyama-shi, Shiga Prefecture F-term within Iwatani Gas Co., Ltd. 2F014 AA10 AB01 AB02 AC02 EA00 3E073 AA01 BB00 CA01

Claims (3)

[Claims] An insulated storage container for storing a low-temperature liquid.
(1) A liquid level gauge (2) is protrudingly arranged in the liquid level detecting device for detecting a liquid level in a container, wherein the liquid level gauge (2) is constituted by a capacitance type liquid level meter, A liquid level detecting device for a low-temperature liquid storage container, characterized in that a gas flow hole (12) of the capacitance type liquid level gauge (2) is opened to a gas phase portion (14) inside the container. 2. An upper surface opening (6) of an insulated storage container (1) is closed with a lid (7), and a capacitance type liquid level meter (2) is passed through the lid (7). The electrostatic capacitance type liquid level gauge (2) is hermetically fixed to the lid (7) in a state where it is inserted into the storage container (1), and the gas is connected to the gas phase part (14) in the storage container (1). The liquid level detecting device for a low-temperature liquid storage container according to claim 1, wherein a discharge pipe (15) is arranged. 3. An insulated storage container (1) comprising an inner tank (3) and an outer tank (4).
The gas flow hole (12) is opened below the inner tank side end of the neck pipe (5) by forming the neck pipe (5) by connecting the two. Liquid level detector for low temperature liquid storage containers.