JPS61223617A - Liquid level indicator at cryogenic temperature - Google Patents

Abstract

PURPOSE:To prevent the occurrence of error by providing a liquid reservoir at the rear of a refrigerant evaporator provided on a bottom side liquid pressure taking-out tube and storing a refrigerant liquid, which cannot be evaporated due to the rise or the variance of the internal pressure of a vessel, in the liquid reservoir not to generate a liquid column difference. CONSTITUTION:If the internal pressure of a vessel 2 rises and the refrigerant liquid exceeds the capability of an evaporated and the capacity of a liquid reservoir 8 and the quantity of penetrating heat are sufficient, a liquid head difference is not generated because the level of the liquid stored in the liquid reservoir 8 is lower than that in the evaporator 7, and the liquid head pressure of the vessel 2 is indicated correctly on a differential pressure gauge 5 to measure an accurate liquid level. A gas space of the liquid reservoir 8 functions as buffer tank to absorb the variance of the internal pressure of the vessel 2, and oscillation of the indication on the differential pressure gauge 5 is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a liquid level gauge used for cryogenic liquids such as liquid helium and liquid nitrogen in cryogenic equipment.

[Technical background of the invention and its problems]

As an example of this type of device, for example, Patent Publication No. 52-2994
4, take out the space pressure above the refrigerant liquid level in the cryogenic refrigerant container and the refrigerant liquid pressure at the bottom of the container,
The pressure difference was measured using a differential pressure gauge, which was a traditional method.

In other words, to explain the conventional device according to FIG. The pressure impulse pipe 4 is connected to one end (two ends) of the differential pressure gauge 5.

Bottom part I of the container 2: The low pressure impulse pipe 6 is led to the evaporator 7, the refrigerant liquid in the pressure impulse pipe 6 is evaporated, and the other end of the differential pressure gauge 5 (; is connected. The reading of the differential pressure gauge 5 is indicates the weight of the refrigerant liquid in the container 2 if the mounting position of the evaporator 7 is correctly aligned with the liquid level at the bottom of the container and the capacity of the evaporator 7 is sufficient. You can know the liquid level.

However, when the internal pressure inside the container 2 increases, the refrigerant gas in the lower impulse tube 6 is compressed, and the pressure impulse tube...? It is generally said that this type of liquid level gauge is unreliable when the pressure rises or fluctuates.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a differential pressure type cryogenic liquid level gauge with less measurement error.

[Summary of the invention]

The present invention provides a differential pressure level gauge that extracts the upper gas pressure and the lower liquid pressure of the refrigerant in a cryogenic refrigerant container and measures the wave height with a differential pressure gauge. A liquid reservoir is provided behind the provided refrigerant evaporator to prevent an error in the $1 liquid # difference due to the increase in the internal pressure of the container exceeding the evaporation capacity of the evaporator.

[Embodiments of the invention]

Figure 1 shows the configuration. It is almost the same as the prior art configuration of FIG. 3, but a cryogenic refrigerant reservoir 8 is added after the evaporator 7. These are placed in a vacuum layer 9 together with the container 2 and are thermally insulated.

FIG. 2 is a diagram showing a more specific embodiment of the present invention.
is a radiation shield in the temperature layer between the refrigerant container 2 and the vacuum insulation container 1. The evaporator 7 is installed in such a way that the evaporation of the refrigerant is promoted and there is no horizontal difference between the refrigerant and the lower end of the refrigerant in the container 2.
At the rear of the evaporator (:, installed at a position lower than the evaporator 7).

In this way, even if the internal pressure of the container 2 increases and the refrigerant liquid exceeds the capacity of the evaporator 7 and the liquid end enters around the rear C2 of the evaporator 7, the volume of the liquid reservoir 8 and the amount of heat introduced will be sufficient. If there is, the liquid accumulated in the liquid reservoir 8 is lower than the liquid level in the evaporator 7.
No wave front difference is generated, the differential pressure gauge 5r: correctly indicates the liquid head pressure in the container 2, and the accurate liquid level can be measured. Further, the space between the gas chambers of the liquid reservoir 8 serves as a buffer tank, absorbing internal pressure fluctuations within the container 2, and has the advantage of suppressing vibrations in the indication of the differential pressure gauge 5.

〔Effect of the invention〕

In the cryogenic liquid level gauge of the present invention, it is possible to prevent C from occurring after the evaporator, and unlike conventional liquid level gauges of this type, errors do not occur during pressure rises and fluctuations, resulting in high reliability. You can obtain flexibility and accuracy.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing an embodiment of the cryogenic liquid level gauge of the present invention, Fig. 2 is a sectional view showing a specific embodiment thereof, j71S
FIG. 3 is a schematic diagram showing a conventional liquid level gauge. 2...Refrigerant container 7...Evaporator 8...Liquid reservoir 5...Differential pressure gauge agent Patent attorney Rules
Kensuke Chika (1 idiot) Figure 3

Claims (1)

[Claims] A differential pressure gauge connected to the upper part of the cryogenic refrigerant liquid container by an upper pressure impulse pipe, an evaporator that draws out the refrigerant liquid from the bottom of the container and vaporizes it, and an evaporator connected to the evaporator that 1. A cryogenic liquid level gauge comprising: a liquid reservoir having a volume and structure that prevents refrigerant liquid from rising above the container; and a impulse pipe connecting the liquid reservoir and the differential pressure gauge.