JPS62261928A - Liquid level measuring instrument - Google Patents

Abstract

PURPOSE:To facilitate data processing for calculating a liquid level by arranging plural thermometers vertically at specific intervals nearby the liquid level and at the side wall part of a tank which contains liquid having a temperature gradient, and computing mean temperature normalized on the basis of measured values. CONSTITUTION:The respective thermometers 31-3n are arranged vertically in a section of temperature variation at almost equal intervals so that even if the liquid level fluctuates, the thermometer 31 is in vapor phase and the thermometer 3n is in liquid phase without fail. Consequently, the temperature at the point of 3n increases monotonously as the liquid level rises and there is a constant function relation between the liquid level and mean temperature. The relation between the mean temperature and liquid level is constant regardless of the absolute value between the vapor phase and liquid phase, the mean temperature normalized by the equation of normalized mean temperature = (mean temperature-vapor phase temperature)/(liquid phase temperature-vapor phase temperature) is computed, and the liquid level in the constant function relation is found on the basis of said computation result.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to the discoloration of measured wheat when the liquid level of a fluid in a tank is measured using the temperature difference between the liquid phase and the gas phase.

<Prior Art> For detecting the liquid level in a tank of a fluid with high viscosity or containing a large amount of foreign matter, a general type of liquid level detection that utilizes changes in differential pressure is often not appropriate.

In this case, it is possible to detect the liquid level using the temperature difference between the liquid phase and the gas phase (liquid phase>vapor phase).

FIG. 9(A) is a block diagram of a device for measuring the level of fluid 2 in tank 1 at a plurality of temperatures 81, 31 + 3
2 + . . . 31 are a plurality of first degree livers inserted at equal intervals into the side wall of the tank, and T + + T 2 + . . . TTL is a temperature measurement value. 3i + 3t ++ is the m degree of the gas phase part and the liquid phase part sandwiching the liquid level 201, and Tl.

TI++ is the reading of these thermometers.

FIG. 9(B) is a temperature distribution diagram in which the measured values of each i-degree liver are plotted, and it can be seen that a temperature difference of ΔT1 occurs between T1 and Tj++.

FIG. 10 is a flowchart of data processing for determining the position of the thermometer where a temperature difference occurs. Tk second hat 1
The measured value of 1, ΔTk, is the temperature difference between +1st and Kli,I, and when a temperature rf1 difference occurs at Kth, it is the liquid level! is determined to be l-.

<Problems to be solved by the invention> However, the problem with this type of determination method is that the results are not obtained as continuous quantities but only as quantized bonds, and in order to make detailed measurements, there are many problems. thermometers, and data processing requires many judgment steps.

It is an object of the present invention to provide a liquid level measuring device that can perform simple data processing as well as simple data processing.

Means for Solving the Problems> The structural feature of the present invention is that the side wall of a tank containing a fluid having a humidity gradient near the liquid level is provided with a vertical a plurality of thermometer means arranged in a direction, a calculation means for calculating a normalized average temperature based on the measured values of these thermometer means, and a function a for calculating a liquid level from the normalized average temperature. The point is that it is equipped with a paralyzing means.

According to the present invention, the normalized average temperature is calculated based on the measured values of the thermometers arranged at rR intervals that are approximately equal to the intervals of temperature change, and the normalized average temperature is calculated using the linear function means from this numerical value. The liquid level is calculated.

Embodiments> The present invention will be explained in detail based on FIG. Components that are the same as those explained in FIG. 9 are given the same reference numerals, and the explanation thereof will be omitted. In the present invention, the intervals between the thermometers are such that even if the liquid level changes, the thermometer 31 is always in the gas phase;
The thermometer 3u is arranged so that the temperature is still in the liquid phase. As shown in FIG. 2, the intervals between the thermometers in the cellar are approximately equal to 6 to 1, the temperature at which the temperature changes from the vapor phase temperature chamber to the liquid phase temperature.

According to this arrangement, the average value of the temperatures at 371 points is the third
As shown in the figure, it increases monotonically as the liquid level increases, and there is a constant □ functional relationship between the liquid level and the average temperature.

Here, if it is assumed that the 88 degree change in the liquid level near chamber shown in FIG. 2 can be approximated by a straight line, then FIG. 2 is represented by a straight line as shown in FIG. Therefore, the functional relationship shown in FIG. 3 can be approximated by a simple straight line as shown in FIG.

The relationship between the liquid level and the average temperature shown in FIGS. 3 and 5 changes as the gas phase temperature and liquid phase temperature change.

However, the following relationship between the normalized average temperature and the liquid level is a constant relationship regardless of the absolute temperature of the gas phase and liquid phase.

Normalized average temperature - (average temperature - gas phase temperature) (liquid phase temperature - vapor phase temperature) When using the normalized average temperature in this way, the relationship between the average temperature and the liquid level is It becomes as shown in Fig. 7.

As described above, in the present invention, first, the normalized average temperature is measured, and then, based on this calculation result, the liquid level having a certain functional relationship is determined.

In Figure 1, the measured value of each thermometer T + + 1-2
+1°...Tu is temperature indication unit 44.4□
, 43...4n and supplied to the 31ir5 unit 5 to calculate the normalized average temperature TN. The calculation formula is TN −((Tl +T2 + ・−−+
1”,,)/n Tl)/(
TuT+).

The output TN calculated in this way is input to the line function unit 6 which executes the function N4 which imitates the characteristics as shown in FIG. be done.

FIG. 8 is a flowchart showing the procedure of the F-9 processing described above, and the processing steps are simplified compared to the conventional method.

The present invention can be effectively applied to the following processes.

■Measurement of liquids such as reaction vessels and single-port tanks, where the liquid level fluctuates rapidly and is affected by agitators, etc., and the signal is disturbed when using a differential pressure type level base, making stable control difficult.

■The corrosion of the contents (fluid) is high, making it difficult to measure with a diaphragm made of normal material.

■It is a 111H process where the internal temperature is high and the pressure is high, and differential pressure transmitters and 1-coat type liquid level gauges can be applied.

<Effects of the Invention> As explained above, according to the present invention, measurement results can be obtained continuously with high accuracy using a small number of thermometers, so that liquid level can be controlled using IR functions by using them as measurement values of a controller. becomes.

In addition, the average value meter and line function function required in the present invention are often prepared as a standardized function package in distributed control devices using a microphone [1 computer], and such a package is not required. By using this method, data processing is extremely simplified compared to the conventional method.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of actual ownership of the present invention, and FIGS.
FIG. 9 is an explanatory diagram of its operation, FIG. 9 is a configuration diagram showing an example of a conventional technique, and FIG. 10 is an explanatory diagram of its operation. 1...Tank 2...Fluid 201...Liquid level 3 +, 32~3u ・=m degree 41.42~
4TL...Temperature indication unit 5...Calculation unit 6...Broken/IQ111 failure unit 7...
Level indication unit Atsushi 1 figure Atsushi 2 figure Atsushi 3 figure Child 4 figure Tsuta 5 figure Tsuta 6 figure TN Edition 7 figure T,,l Tsuta figure 9 (A) (B) Figure 10

Claims (1)

[Claims] A plurality of thermometer means arranged vertically on the side wall of a tank containing a fluid having a humidity gradient near the liquid level at intervals approximately equal to the interval of temperature change, and the measured values of these thermometer means. A liquid level measuring device comprising: calculation means for calculating a normalized average temperature based on the normalized average temperature; and function calculation means for calculating a liquid level from the normalized average temperature.