JPH0361893B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 3.1 Technical Field The present invention relates to a method for measuring the level of a surface of a liquid or granular material in contact with gas, that is, the surface level, and an apparatus for carrying out the method.

More specifically, the present invention relates to a method and apparatus for thermally measuring a liquid level or a surface level of powder or granular material using a sensor that combines a heater and a temperature measuring element, that is, a quantitative surface detection element.

3.2 Prior Art There have been many methods for measuring surface level, such as direct reading method, float method, gravimetric method, pressure method, electric method (capacitance method etc.), sonic method,
There are radiation type, microwave type, rotating body type, weight type, vibrating piece type, etc., but depending on the method,
Manufacturing costs are high, there are concerns about radiation contamination,
It had drawbacks such as requiring strict calibration, being mechanically fragile, not having an explosion-proof structure, and not being able to be measured from outside the container.

3.3 Purpose of the present invention The purpose of the present invention is to provide a method and an apparatus for measuring a quantitative surface level without the above-mentioned drawbacks. A temperature measuring element such as a multi-pronged thermocouple is installed to measure the temperature distribution in the longitudinal direction of the heater and the heater inside or on the surface, and a coating layer is further applied to the surface for electrical insulation, mechanical or chemical protection. It has an extremely simple structure.

Features of the quantitative level measuring method and device according to the present invention are (1) Since the sensor can be made from inexpensive materials, the manufacturing cost is low.

(2) Quantitative detection is performed from the temperature distribution during heating, so unlike radiation-based methods, there is no risk of contamination of the substance to be measured.

(3) This is a detection method based on the temperature distribution during heating, and since the quantity is detected from the relative change in temperature, strict calibration is not required.

(4) Unlike the float type, there are no moving parts, so there is less chance of mechanical damage.

(5) The sensor can be coated with Inconel or stainless steel, making it explosion-proof.

(6) It is also possible to measure the amount by inserting it inside a liquid or powder, or by attaching a sensor to the outside surface of the container.

and so on.

3.4 Principle and structure of the present invention 3.4.1 Principle The height surface of liquid or granular material is flat, and the thermophysical property values (thermal conductivity, heat transfer coefficient (in case of fluid) of an object in contact with the flat surface) ) is different from that of the liquid or powder, the temperature inside or on the surface of a long homogeneous heating element (cylindrical heater, linear heater, flat heater, etc.) disposed perpendicular to the boundary surface. Assuming a temperature distribution, the temperature distribution is determined by the thermal conductivity and heat transfer coefficient of the object in contact with the surface. It is estimated that the temperature distribution of the heating body causes a rapid temperature change near the boundary surface. The present invention relates to a surface level measuring method and apparatus for measuring the surface level of liquid or powder based on this idea.

To make the explanation more concrete, as shown in Figure 1, when a liquid or granular material and a gas are in contact with each other with a plane as their boundary, a long uniform heating element (hereinafter simply referred to as the heating element) is perpendicular to the boundary. Consider the temperature distribution inside or on the surface of the heating element when it is placed in the heating element.

FIG. 1 is a schematic diagram in which a region I of liquid or granular material and a region of gas are in contact with each other at a boundary surface 2, and a heating element 1 is arranged perpendicularly to this boundary surface.

FIG. 2 shows an example of the temperature distribution in FIG. 1, and solid lines a and b and broken lines 3 and 4 indicate the temperature distribution in the vertical direction of the heating element.

In the figure, it is assumed that the heating element is manufactured so that the amount of heat generated is uniform in the length direction.

When the heating element does not generate heat, the temperature of the heating element is determined by the temperature distribution determined by the external temperature field, for example, as shown by broken lines 3 and 4 in FIG. In some cases, the entire heating body has a uniform temperature distribution3,
A case in which there is a temperature change as in 4 is also conceivable.

From this state, an appropriate amount of heat is then emitted from the surface of the heating element. The heat may be generated in pulses or in steps.

To make it easier to understand, heating is performed in fixed steps starting from a certain time, and the temperature distribution of the heating element when a steady state is reached is shown by solid lines a and b in the same figure.
A distribution like this is possible. In other words, the temperature increase due to heating is given by a-3 and b-4 in the same figure, and if the thermal conductivity and heat transfer coefficient of the material with the region differ, the temperature distribution of the heating body near the interface will change. It exhibits a rather abrupt change, that is, an inflection point. In other words, by measuring the temperature distribution of the heating element, there is a boundary surface at the inflection section where a sudden temperature change occurs, and therefore the height of the region (boundary surface) is known.

In the above, in order to find the position of the boundary surface, the difference between the temperature distribution of the heating element before and after heating was calculated because, for example, as shown in Figure 3, the temperature distribution before heating happened to be along the broken line in the same figure. This is because considering the possibility that the temperature distribution after heating may become substantially uniform as shown in the solid line c in the figure. That is, it is difficult to determine where the boundary surface exists from the state of the temperature distribution of c. but,
If we take the difference c-5 between the temperature distribution 5 before heating and the temperature distribution c after heating, a temperature change will certainly occur.

Based on this estimation, in this measurement principle, a method is always adopted in which the position of the boundary surface is determined by the difference between the temperature distribution of the heating element when it is not heated and the temperature distribution of the heating element after heating.

The above explanation was about the method of determining the surface level of the region from the temperature distribution of the heating element in a steady state, but even before the steady state is reached, that is, in a transient state, the temperature before heating the heating element and the temperature at that transition point are By taking the difference from the temperature, the surface level of the area is known. In this case, it is considered that the thermal diffusivity is dominant in the thermophysical property value of the object in the region that determines the temperature distribution in the transient state. Furthermore, as a measurement method in a transient state, the heat generation from the heating body can be carried out in a pulsed manner.

Next, when determining the height of the liquid level, which is considered to be the majority of uses for this measuring device, in other words, when the object in the area is a liquid such as petroleum, hydrocarbon-based organic liquid, or aqueous solution, the object in the area is air or a liquid filled with water. The relationship between the temperature distribution of the heating body and the liquid level when the heating body is a gas such as gas will be explained.

The temperature distribution of the heating element when the heating element is generating heat, whether in a steady state or an unsteady state, is caused by convection in the liquid in the area due to heating, and as shown in Figure 4, the temperature at the surface layer of the heating element increases. rises. This phenomenon is often experienced when boiling a bath.

That is, when determining the boundary surface from the temperature distribution of the heating body, the temperature distribution inside the liquid (portion C) with high thermal conductivity becomes uniform, but the temperature rise point A always occurs inside the liquid. Therefore, if the boundary surface is determined from point A, the liquid level will be evaluated as low by Δl.

On the other hand, if the boundary surface can be found from point B, accurate evaluation can be made, but since point B is a point in the temperature change, it seems difficult to find this point. A possible solution to this problem would be to vary the amount of heat generated by the heating element, find the temperature distribution for each, and perform numerical analysis based on the temperature changes, but this would require knowing the thermophysical properties of the liquid or gas.
Therefore, in practical terms, the key point is to measure the temperature at a temperature increase that is small enough to detect a temperature change in the heating element.

Also, considering that the liquid level will always be lower when calculating from point A, when the target liquid and heating method are determined, the correct liquid level can be determined by adding a correction value (Δl) to the measured liquid level. The face is known.

Regarding the error in liquid level evaluation due to the above convection,
Similar consideration is required when determining the amount of powder or granules, since the powder or granules contain gases such as air. Note that in a forced convection state where the liquid is stirred, the effect of the above-mentioned convection can be ignored, so if possible, measuring the liquid while it is in an agitated state also leads to highly accurate measurements.

3.4.2 Measurement method and device structure This section describes the measurement method and structure and configuration of the device that satisfies the above principles.

The shape of the heating body used in the present invention is an elongated cylindrical heater, a linear heater, a flat plate heater, etc.
Both are uniform heating bodies. The number of quantitative surface detection elements used is one in the first method invention, and a plurality of quantitative surface detection elements in the second method invention. Since the first method uses one quantitative surface detection element, the temperature difference distribution of the same level in the longitudinal direction of the heating body of this detection element before and after heating is determined. In addition, the heating method is stepwise or pulsed.
Continuous heating is not possible. In the second method, multiple quantitative surface detection elements are used, so at least one of them is used for heating and one for reference. It is used for temperature distribution measurement. The heat generation amount surface detection element and the reference amount surface detection element are placed at a certain distance apart so that the reference heating element is not affected by the heat generated by the heat generation heating element. Continuous heating can also be used.

Next, the temperature measuring element that measures the temperature distribution of the heating body, that is, the heater, is a multi-branched thermocouple with a common positive or negative wire, a normal thermocouple, a differential thermocouple, a resistance thermometer, or Use a thermistor. In multi-branched thermocouples, the thermocouple wire is also used as a heater wire to generate a certain amount of heat from an AC power source, and the temperature at a temperature measurement point or the temperature difference between temperature measurement points can be detected as a DC voltage. .

The above-mentioned heating body, that is, the heater, and the temperature measuring element are combined to constitute a sensor which is a quantitative surface detecting element, and an example of its configuration and structure are shown in FIG. In Fig. 5A, a temperature measuring element 6 is arranged on the surface of a spiral heater 7, and a filler 1 such as alumina powder or magnesia powder is used.
1, and the entire body is covered with a coating material 10 such as a polymeric material or stainless steel to form an elongated cylindrical sensor 2.
5. Figure B shows the case where the heater in Figure A is linear. In the same figure, a temperature measuring element 6 is mounted on one surface of a flat plate-shaped uniform heater 9, and a heat insulating material 2 is mounted on the other surface.
4 are arranged and the whole is covered with a covering material 10 to constitute a flat sensor. 2 shows a sensor 25 in which a temperature measuring element 6 is arranged inside a heater 7 as shown in FIG. In the figure (E), a sensor 25 is constructed by arranging a temperature measuring element 6 inside a cylindrical heater 7 when a stainless steel pipe or the like is used as the heater. In the figure, a sensor 25 is constructed using a heater/temperature measuring element 8 that serves both as a temperature measuring element and a heater.

Next, the coating color that governs the surface emissivity of the sensor will be explained.

When heat from the sensor is dissipated into the gas, it is transferred by convection and radiation heat transfer. If the emissivity of the sensor surface is made low, such as with a metallic or mirror-finished surface, even if the amount of heat generated from the sensor is small, the temperature rise of the sensor on the gas side will be large, resulting in the above-mentioned problem. This is advantageous when detecting the liquid level or powder surface from a curved part where the temperature changes rapidly. However, if the sensor is used for a long period of time, it is assumed that dirt will occur on the sensor surface and the emissivity will increase. It is necessary to consider sensor surface treatments such as color development.

In addition, based on the above points, since the emissivity always increases due to dirt, it is necessary to paint or oxidize the sensor surface in advance so that the emissivity ε becomes large (for example, ε = 0.9 to 0.95). It is also necessary to carry out this procedure in order to ensure stable measurement over a long period of time.

Next, as a power source for heating the heater, it is necessary to use a stabilized DC or AC power source. A digital thermometer, digital voltmeter, data logging meter, or the like can be used as a measuring device for measuring the temperature of each hot junction of the temperature measuring element. One method is to measure the temperature at each temperature measurement point with these measuring instruments and use that data to determine the temperature difference distribution between heating and non-heating, but it is also possible to It is convenient to input the information, calculate the temperature distribution or temperature difference distribution, and display the pattern of the distribution.

Regarding the mounting method of the quantitative surface detection element, it may be directly inserted into the liquid or powder, or it may be attached to the surface of a container containing the liquid or powder.

3.4.3 Examples The method and apparatus of the present invention will be described in detail below according to one embodiment thereof.

The structure of the sensor used is shown in Figure 6a. In the figure, the uniform heating body is in the shape of a flat plate, and the temperature measuring element uses one thermocouple wire of the constant ribbon wire 13 as a common wire, and a number of thermocouple wires of the chromel ribbon wire 12 forming a pair are arranged at regular intervals. This is a multi-branched thermocouple welded with In addition, the cross-sectional shape of the sensor is such that an aluminum plate 15 for soaking heat, a polyimide adhesive sheet 16, and a multi-branched CRC thermocouple are arranged in this order on one surface of the surface heater 17, and the whole is further covered with a polyimide adhesive sheet 16. There is. Two sensors with this structure were used.
Figure b shows a circuit diagram in which a DC stabilized power source is connected to the heater, and a multi-branched thermocouple is connected to a digital logging meter.

Next, use one of the two sensors for heating and the other for reference (a sensor that detects temperature distribution without heating), and make sure that the thermocouple contacts are at the same level for both heating and reference. The sensor distance is approx.
They were arranged at 50mm intervals. If this distance is too close, the influence of temperature rise due to heating will occur on the temperature distribution on the reference side, so care must be taken, but from 30 mm to
Approximately 200mm seems appropriate.

Figure 7 shows an outline of the experimental conditions.

In the figure, a reference sensor 20 and a heating sensor 21 connected by a fixture 18 were placed in a plastic container 19.

As target substances for level detection, tap water was selected as the liquid, and alumina powder was selected as the powder.

A MC-L data logging meter manufactured by Showa Denko Co., Ltd. was used as a temperature measuring device, and a DC stabilized power source was used as a heating power source.

When measuring the temperature distribution, the measurement accuracy of the data logging meter was very good at 0.1°C. CRC thermocouples having contacts 1 to 9 were used as temperature measuring elements to measure the temperature distribution. In addition, as a method of measuring the temperature distribution, the temperature of contact 1 may be determined, and then the temperature difference between contacts 1 and 2, contacts 2 and 3, etc. may be treated as a differential thermocouple.

Water level measurements were carried out using this device. For the purpose of investigating the relationship between the distance between temperature measurement points and the measured water level, that is, the detection error, experiments 1 to 4 were conducted with different water levels. The conditions of these experiments are shown in FIGS. 8 to 11.

In FIGS. 8 to 11, 4C to 15S are contact numbers, 20 is a reference sensor, and 21 is a heating sensor.

The power input to the heater was 12 W, and the heat was radiated to both sides of the sensor, so the heat flow density per unit area was set to about 270 W/m ² in the experiment.

(b) The results obtained in Experiment 1 are shown in Figure 12. In the results shown in Figure 12, curve 1 shows the contact temperature of the heating side sensor and the temperature of the reference side contact at the same level as that contact (for example, 1 and 10, 5 and 14, etc.) when no heat is generated from the heating side sensor.
shows the difference between Where it should be 0℃±
There is a variation of about 0.5℃. This is caused by uneven temperature of water or air, differences in thermoelectromotive force between thermocouples (variations in thermocouple wires), and uneven temperatures at the input contacts (cold junctions) of the data logging meter used as a measuring device. considered to be a thing.

Curve 2 shows the surface temperature distribution on the heating side when heat is generated from the heating side with an input power of 12 W, and the surface temperature on the reference side where no heat is generated.

Curve 3 is a curve obtained by calculating (heating side temperature - reference side temperature) with respect to curve 2. The method for determining the water level from these curves is described below.

() To find the water level from curve 3, use tangent point 6,
Since the temperatures at points 7, 8, and 9 are approximately constant,
It can be seen that there is a water level at the inflection part near the contact point 6.

() Furthermore, in order to obtain more precisely, the relationship between the degree of temperature rise ΔT and the height (temporarily substituted by height x) at contact points 3, 4, and 5 of curve 3 is, for example, ΔT=ax ² +bx+c ……(1) Then, calculate the value of x at which ΔT becomes the average value of the positions of contact points 6, 7, 8, and 9 (ΔT=1.2°C in FIG. 12).

Reading the relationship between x and ΔT from curve 3 in Figure 12 and substituting it into equation (1) to find a, b, c, we get ΔT=-1.04x ² +7.77x+1.09...(2), and ΔT When we find the value of x when = 1.2℃, we get x = 0.014. In other words, 0.014× from the position of contact 6
It is measured that the water level is 40mm≒0.6mm above. Note that the approximate expression may be a cubic expression instead of a quadratic expression.

() Next, in order to obtain more precisely, the variation in the 0 temperature level of curve 1 is corrected. In other words, using the temperature rise ΔT corrected by (curve 3 - curve 1), the above ()
Determine the water level using the method described in .

() () () The above principle 3.4.1
The water level will be lower than the actual water level, as explained in Figure 4 in Section 2. This is actually shown in FIG. This correction method requires preliminary experiments, but it is best to calculate the error when the water level is at the same level as the contact point and use that value to correct it, or as a rough guide, it is best to calculate the error when the water level is at the same level as the contact point. One possibility is to add the half value to the value obtained by () () (). This point will be explained later, including the results of Experiments 2 to 4.

(b) The results obtained in Experiment 2 are shown in Figure 13. The water level is at contacts 5 and 6 (14 and 15 on the reference side)
These are the experimental results when the contact point 6 is located 30 mm above the contact point 6. The five data shown by curve 3, which reached a steady state after heating, give results that are in good agreement. Based on these results, constants a, b, and c are determined from the quadratic equation approximation ΔT=ax ² +bx+c in the same way as in Experiment 1, and x that gives ΔT=1° C. is determined to obtain x=0.03. That is, the measurement level is 1 mm above the contact point 6, indicating a position 29 mm lower than the actual position.

It should be noted that the above-mentioned error becomes narrower as the distance between the contacts becomes narrower, and the temperature distribution in the vicinity of the water level becomes clearer, thus making it possible to measure with a smaller error.

(c) Next, the results obtained in Experiment 3 are applied to the 14th experiment.
As shown in the figure. This is the result of measurement when the water level is at the same level as the contact point 514 and the air and water temperatures are approximately equal. As in Experiments 1 and 2, when the water level is determined by quadratic approximation of the relationship between ΔT and x, the water level is found above contact point 6.
Rated as 27mm position. In other words, when the contact and the water level are at the same level, the measurement level is below the water level.
It turned out to be 13mm. This error is determined by the amount of heat emitted from the sensor and the thermophysical properties of the liquid and gas, so once the object to be measured (liquid and gas) is determined, the amount of heat generated and the distance underwater to be measured must be calculated in advance. For example, it can be used as a correction value.

(d) Furthermore, in Experiment 4, the liquid and gas before heating were not at uniform temperature; for example, the purpose was to evaluate measurement errors when evaluating the liquid level when the liquid temperature was low and the gas temperature was high. This is an experiment. Figure 15 shows the results obtained. The water level determined from Figure 15 is 18 mm below the water surface, which is in good agreement with the results of Experiment 3.

The errors in the above measurement results are summarized as follows.

In experiment 1, the measured level was -19 below the actual water level.
mm (meaning under water) In Experiment 2, the measured level was -29 below the actual water level.
mm (meaning under water) In Experiments 3 and 4, the measured levels were -13 mm and -18 mm (meaning under water) from the actual water level.The results can be summarized as follows.

(a) From this result, first, in the case of this sensor where the contact spacing is 40 mm, the level can be found with an error within the range of that spacing.

(b) As is clear from Figure 4 and the above results,
Considering that this thermal level detection always estimates the level below the liquid surface, we used the error when the contact and the liquid were at the same level, that is, the average value of 15 mm of the results of Experiments 3 and 4, as the correction value. -19+15=-4mm error In Experiment 2 -29+15=-14mm error In Experiments 3 and 4 -13+15=+2mm, -18+
The error is 15=-3mm, and the level can be determined with a measurement error within 20mm of the half value of the contact spacing.

Next, as an experiment to detect the level or quantity of powder and granules, alumina powder (A-1 manufactured by Showa Denko Co., Ltd.) was tested.
Experiments 5 and 6 were carried out by selecting the material to be tested. The details of the experiment are shown in Figures 16 and 17.

4S to 17C in Figures 16 and 17
is a contact number, 2 is an interface, 20 is a reference sensor, 21 is a heating sensor, 22 is air, 23
is alumina powder.

The power input to the heater is 27W, and the heat is radiated to both sides of the sensor, so the heat flow density per unit area is approximately 600W/ ^m2 .

(e) The results obtained in Experiment 5 are shown in FIG. FIG. 18 shows one piece of data when a steady state is reached after a sufficient period of time has elapsed after heat generation.

Curve 1 shows the contact temperature of the heating side sensor when no heat is generated from the heating side sensor.
It shows the value obtained by subtracting the reference side contact temperature (for example, a combination of 5S and 14S) that is at the same level as that contact. There is a variation of about ±0.5°C where it should be 0°C.

Curve 3 is a curve obtained by calculating (heating side temperature - reference side temperature) between the temperature distribution on the heating side when heat is being generated from the heating side with input power of 27W and the temperature distribution on the reference side where no heat is being generated. Curve 4 is (Curve 3 - Curve 1), that is, [When heat is generated from the heating side (temperature on the heating side - temperature on the reference side)] - [When no heat is generated from the heating side (temperature on the heating side - reference side)] side temperature)] …(3) shows the temperature distribution.

In equation (3), if the temperature distribution on the reference side does not change whether heat is being generated from the heating side or not, the result will be the temperature difference between "when heating and before heating" on the heating side. Therefore, there is no point in installing a reference sensor, but the temperature on the reference side, which is not generating heat, may also change due to changes in the room temperature before heating starts and reaches a constant state, or the temperature on the reference side, which is not generating heat, may change, or the temperature on the reference side, which is not generating heat, may be affected by the heat generation of the heating side sensor. It is thought that the temperature distribution of the reference side sensor may be slightly affected, and therefore, it has been found that correction of the 0 temperature level using equation (3) is effective.

From the results in Figure 18, the alumina level is contact point 5.
It can be inferred that the contact point 6S or contact point 6S is present, or somewhere in between. Comparing and examining the temperature distribution of the actual alumina surface and the obtained curves 3 and 4, it can be considered that the effect near the alumina surface is due to the convection of air existing in the alumina powder described above.

Here, if the alumina surface position is determined as the intersection of the curves of contact positions 6S, 7S, 8S, and 9S and the straight lines of contact positions 4S and 5S, 5
It is found to be at a position ~10mm above.

(F) The results obtained in Experiment 6 are shown in FIG. 19. Estimating from the temperature distribution, it can be seen that the alumina surface exists between the contact points 6S and 7S.
Furthermore, if it is known in advance that the alumina surface exists at a position 1 to 2 degrees Celsius higher than the temperature distribution on the air side, the result shown in Figure 19 is that the alumina surface found is Measured as 10-15mm above.

From the above two experiments, it was found that even for powders such as alumina, by using this sensor with a contact spacing of 40 mm, the level can be determined with an error of within ±15 mm.

3.5 Effects of the present invention Since the present invention is configured as described above,
The sensor can be made from inexpensive materials, does not require strict calibration, and has no moving parts, so it is less likely to break down. Furthermore, the sensor can be made explosion-proof by using metal as the covering material, and the sensor can also be attached to the outer surface of the container to detect the quantity.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the principle of the present invention, Figure 2 is an explanatory diagram of the temperature distribution of the heating element, Figure 3 is an assumed diagram of the temperature distribution of the heating element before and after heating, and Figure 4 is the temperature distribution of the heating element. FIG. 5 is a diagram illustrating the structure of the sensor. Figure 6 is the structure diagram and measurement circuit diagram of the sensor, Figure 7 is
The figure is a schematic diagram of the experimental apparatus of the example, Figures 8 to 11 are illustrations of experiments 1 to 4, Figure 12 is an illustration of the results of experiment 1, Figure 13 is an illustration of the results of experiment 2, and Figure 14 is an illustration of the results of experiment 2.
The figure is an explanatory diagram of the results of Experiment 3, Figure 15 is an explanatory diagram of the results of Experiment 4, Figure 16 is an explanatory diagram of the experimental method of Experiment 5, Figure 17 is an explanatory diagram of the experimental method of Experiment 6, and Figure 18 is an explanatory diagram of the experimental method of Experiment 5. FIG. 19 is a diagram explaining the results of Experiment 6. 1: Heating body, 2: Boundary surface, 3, 4, 5: Temperature distribution, 6: Temperature measuring element, 7: Heater, 8: Heater and temperature measuring element, 9: Flat plate-shaped soaking heater, 10: Covering material,
11: Filler, 12: Chromel ribbon wire, 13:
Constantan ribbon wire, 14: Contact, 15: Aluminum plate for soaking, 16: Polyimide adhesive sheet, 1
7: Surface heater, 18: Fixture, 19: Plastic container, 20: Reference sensor, 21: Heating sensor, 22: Air, 23: Alumina powder, 24:
Insulation material, 25: sensor, 0S to 17S: contact,
:Liquid or powder region, :Gas region, a,
b, c: Example of temperature distribution.

Claims (1)

[Claims] 1. A method for measuring the level of a surface where a liquid or powder or granular material is in contact with a gas, in which a pulse-like or step-like a temperature distribution in the longitudinal direction of the uniformly heated body when a constant amount of heat is being generated;
Measure the temperature distribution in the longitudinal direction of the soaked heating element when no heat is generated from the soaked heating element, determine the distribution of temperature differences between the two at the same level, and calculate the actual temperature of the soaked heating element. A quantitative surface level measurement method characterized by detecting the quantitative surface from an inflection part of the temperature distribution in the vertical direction of the degree of rise. 2. A method for measuring the level of a surface where a liquid or granular material is in contact with gas, in which a plurality of soaking heating elements for heat generation and reference are arranged at intervals perpendicular to the level of the surface, A constant amount of heat is generated from the heat generating uniform heating body, and no heat is generated from the reference uniform heating body, and the distribution of the temperature difference between the two at the same level is determined. A method for measuring a quantitative surface level, characterized by detecting a quantitative surface from an inflection part of a longitudinal temperature distribution of a substantial degree of temperature rise. 3. A temperature measuring element having a plurality of temperature measuring points for detecting the temperature distribution in the longitudinal direction on the surface or inside of an elongated cylindrical, flat or linear heating body,
and a covering material surrounding both of them, a stabilized power supply for heating the uniform heating body when generating a constant amount of heat, and each temperature measuring element of the temperature measuring element. a measuring device for detecting the temperature at a point, and calculating the distribution of the temperature difference between two equal-level members in the longitudinal direction of the uniform heating body when the uniform heating body is generating heat and when the uniform heating body is not generating heat; 1. A quantitative surface level measuring device, comprising: a calculator for displaying information. 4. A long and slender cylindrical, flat or linear temperature soaking body, a temperature measuring element having a plurality of temperature measuring points for detecting temperature distribution in the longitudinal direction on or inside the body;
and a plurality of quantitative surface detection elements for heat generation and reference, each of which is made up of a covering material surrounding both of them;
a stabilized power supply for generating heat for the heat generation amount surface detection element having a uniform heating body that generates a constant amount of heat; a measuring device for detecting the temperature at each temperature measurement point of the temperature measurement element; and the heat generation amount surface detection element. A quantity surface level characterized by comprising a calculation unit that calculates and displays the distribution of temperature difference between the same level in the longitudinal direction between the uniformly heated body of the element and the uniformly heated body of the reference volume level detection element. measuring device. 5. The quantitative surface level measuring device according to claim 3 or 4, wherein the temperature measuring element is a multi-branched thermocouple having a common wire that also serves as a uniform heating element.