JPH05288591A - Hot liquid level detecting method and device thereof - Google Patents

Abstract

PURPOSE:To detect a liquid level of high temperature or low temperature hot liquid by providing a plurality of thermometers in different heights, and detecting a temperature gradient or a temperature changing time when a temperature of storage liquid is changed. CONSTITUTION:Thermocouples 3 and 4 are provided in a storage tank 1 in different detection heights, and the thermocouple 3 is soaked in hot liquid 2, and the thermocouple 4 is exposed. A temperature detector 5 is connected to the thermocouple 3, and a temperature detector 6 is connected to the thermocouple 4. The hot liquid 2 is heated. A temperature of the thermocouple 3 rises almost synchronously. The thermocouple 4 is heated by means of the atmosphere in the storage tank 1 and radiation heat from the surface of the hot liquid 2. Thereby, respective rising curves obtained by carrying out an operation by means of a computing unit 7 according to respective detecting temperatures of the detectors 5 and 6 become different from each other. Then, temperature gradient data are collected beforehand by means of an experiment and so on, and are inputted to a memory unit 8, and an operation is carried out on respective temperature rising curves from the detectors 5 and 6, and operation is also carried out on a temperature gradient, and these are referred to storage data of the memory unit 8, so that a liquid level can be measured.

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 a hot liquid, for example, a liquid level detecting device for detecting a liquid level of a high temperature liquid in a liquid material supplying device of a film forming apparatus of a semiconductor manufacturing apparatus. is there.

[0002]

2. Description of the Related Art Conventional liquid level detecting devices include a float type, a liquid level sensor, and an ultrasonic type.

[0003]

In the above-mentioned conventional liquid level detector, there is a seal for mounting components in a liquid-tight manner, or an electrical component is used. For this reason, when the liquid to be detected has a high temperature, it is not applicable, and at present, no suitable liquid level detection device for the high temperature liquid has been embodied. In addition, even when the stored liquid is heated or cooled and there is a large temperature difference in the stored state, there is currently no suitable liquid level gauge.

In view of the above situation, the present invention aims to provide a hot liquid level detecting method and apparatus capable of detecting the liquid levels of hot and cold hot liquids.

[0005]

The present invention is characterized in that the liquid level is detected by detecting the temperature gradient or the temperature change time when the temperature of the stored liquid is changed.

[0006]

When the temperature of the stored liquid is changed, the temperature change behavior varies depending on the liquid level of the stored liquid. Therefore, the liquid level is detected by detecting the temperature change gradient, which is one of the behaviors,
Alternatively, the liquid level can be detected by detecting the time of temperature change.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a storage tank, and 2 is a warm liquid stored in the storage tank 1. In the storage tank 1, thermocouples 3 and 4 are provided with different detection heights so that there is a difference of height h.

A temperature detector 5 is connected to the thermocouple 3,
A temperature detector 6 is connected to the thermocouple 4. The temperature detector 5 and the temperature detector 6 are connected to a calculator 7, and a memory 8 is connected to the calculator 7.

As shown in the figure, it is assumed that the one thermocouple 3 is immersed in the warm liquid 2 and the other thermocouple 4 is exposed from the warm liquid 2.

The warm liquid 2 is heated to raise the temperature by ΔT. Since the thermocouple 3 is immersed in the warm liquid 2, the temperature rises substantially in synchronization with the temperature rise of the warm liquid 2. However, since the thermocouple 4 is exposed from the warm liquid 2, it is heated through the atmosphere in the storage tank 1 and by the heat radiation from the surface of the warm liquid 2. Therefore, as shown in FIG. 2, the rising curve a calculated by the calculator 7 based on the temperature detected by the temperature detector 5 and the calculation based on the temperature detected by the temperature detector 6 are calculated. It is different from the rising curve b calculated by the device 7.

Thus, the closer the thermocouple 4 is to the liquid surface of the warm liquid 2, the temperature rise curve b detected by the temperature detector 6 becomes the temperature rise curve a detected by the temperature detector 5. The closer the thermocouple 4 is to the liquid surface of the warm liquid 2,
The temperature rise curve b detected by the temperature detector 6 is the temperature detector 5
Deviates from the temperature rise curve a detected by.

Therefore, data of the temperature gradient of the temperature rise curve b, which has the distance from the liquid surface of the thermocouple 4 as a parameter, is obtained in advance from the temperature gradient of the temperature rise curve a by experiments, and this data is referred to as the above. Input to the memory device 8,
Based on the detection results from the temperature detector 5 and the temperature detector 6, the calculator 7 calculates the temperature rise curve a and the temperature rise curve b, further calculates the temperature gradient of both curves, and the calculation result is stored in the storage unit. The liquid level can be measured by referring to the data stored in 8.

In the above description, the case where the stored liquid is heated has been described, but also when cooling the stored liquid, the liquid level can be detected by the difference in the temperature gradient of the temperature decrease curve.

Further, although two thermocouples are provided in the above embodiment,
As shown in FIG. 3, one thermocouple 3 may be provided at a position where it is not immersed in the warm liquid 2. In this case, the liquid level is measured by storing the data of the heating conditions of the heating device, the liquid level, and the temperature gradient calculated based on the temperature detected by the thermocouple 3 using the distance from the liquid level as a parameter. can do. or,
Although the thermocouple is used as the temperature sensor, another temperature sensor may be used.

Further, as shown in FIG. 4, a thermocouple 4 may be provided at a position where it is constantly immersed in the warm liquid 2. In this case, the gradient of the temperature rise curve is calculated in the same manner as described above, the heat capacity of the warm liquid 2 is obtained from this gradient and the heating conditions of the heating device, and the volume of the warm liquid 2 is calculated from the specific heat of the warm liquid 2, Further, the liquid level is obtained from the shape of the storage tank 1.

Further, when detecting a rough liquid level, a plurality of thermocouples having different heights may be provided to detect up to which position the warm liquid 2 is immersed in the thermocouple.

Further, in the above embodiment, the liquid level is detected by the temperature gradient of the temperature rise curve. However, instead of the temperature gradient, the time to rise to a predetermined temperature or the time until the temperature rise is saturated It goes without saying that it is possible to measure the liquid level based on Further, although the above-mentioned embodiment has been described with respect to the high temperature liquid, it is needless to say that the same can be applied to the detection of the liquid level of the low temperature warm liquid.

[0019]

As described above, according to the present invention, it is possible to measure the liquid level of a warm liquid such as a high temperature liquid.

[Brief description of drawings]

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

FIG. 2 is a diagram showing that the behavior of temperature rise differs depending on the liquid level of the warm liquid and the position of the measurement point.

FIG. 3 is an explanatory view showing another embodiment of the present invention.

FIG. 4 is an explanatory diagram showing still another embodiment of the present invention.

[Explanation of symbols]

 1 Storage Tank 2 Hot Liquid 3 Thermocouple 4 Thermocouple 5 Temperature Detector 6 Temperature Detector 7 Computing Unit 8 Memory

Claims (5)

[Claims] 1. A method for detecting a hot liquid level, which comprises detecting a temperature gradient when a temperature of a stored liquid is changed to detect the liquid level. 2. A plurality of thermometers are provided with different heights,
A method for detecting a hot liquid level, which comprises detecting the liquid level from the difference in temperature gradient between thermometers when the temperature of the stored liquid is changed. 3. A warm liquid level detecting method, which comprises detecting a temperature change time when the temperature of the stored liquid is changed to detect the liquid level. 4. A plurality of thermometers are provided with different heights,
A method for detecting a hot liquid level, which comprises detecting a liquid level from a difference in temperature change time between thermometers when the temperature of a stored liquid is changed. 5. At least one thermometer, a calculator for calculating the temperature change state of the warm liquid based on the detection result from the thermometer, and a correlation between the heating condition, the temperature change state, and the liquid level. And a storage device for storing the liquid level.