JPS5967421A - Level gage - Google Patents

Abstract

PURPOSE:To improve the accuracy in measurement of a level and to simplify the construction of an apparatus, by comparing the electric resistance values of first, second and third electric resistance wires stretched in liquid-phase and vapor-phase portions and in the direction of the height thereof inside a tank, with one another. CONSTITUTION:When a prescribed small current is made to flow through electric resistance wires 221, 222 and 223, a heat is radiated from each electric resistance wire. The vapor and liquid of a hydrogen isotope show different thermal conductivity as shown in the third table, and the electric resistance wires take electric resistance values in accordance with temperature. Accordingly, the electric resistance value of the electric resistance wire 223 is in accord with the level of a mixed liquid 2. Therefore, by inputting to an arithmetic unit 2 the electric resistance values of the electric resistance wires 221 in the mixed liquid 2 and of the electric resistance wire 222 in the vapor 3 respectively and by substituting said values for the electric resistance values on the mixed liquid 2 side and vapor 3 side of the electric resistance wire 223 for operational processing, it turns possible to calculate the level of the mixed liquid 2 and to take it out as an output signal 26. Thus, the accuracy in measurement can be improved, while the structure of the gage can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid level needle for measuring the liquid level of a mixed liquid of hydrogen isotopes.

A liquid level needle that measures the liquid level in a tank uses a differential pressure gauge to detect the difference between the pressure at the bottom of the tank and the pressure inside the tank above the liquid level, and calculates the liquid level from the differential pressure and the density of the liquid. Pressure type liquid level gauges are known. However, this differential pressure type liquid level gauge produces errors when the density of the liquid changes, such as in the case of mixed liquids, so it is necessary to know the density of the liquid by some means.

For example, when measuring the liquid level of liquid hydrogen, a differential pressure type liquid level needle has conventionally been most commonly used, but since the density of hydrogen isotope liquids differs greatly as shown in Table 1 below, The liquid hydrogen level needle is constructed as shown in FIG.

In FIG. 1, 1 is a reboiler of a hydrogen isotope cryogenic distillation column, and a mixed liquid 2 of hydrogen isotopes is stored in the reboiler 1.
Above the vapor 3 exists in equilibrium with the mixed liquid 2, and a heater 4 is installed within the mixed liquid 2. The vapor 3 at the top of this reboiler 1 and the mixed liquid 2 at the bottom
Detection pipes 5.6 are inserted into each of the detection pipes 5.6, and these detection pipes 5.6 are connected to a differential pressure converter 7. Also,
A sampling pipe 8 is inserted into the mixed liquid 2 at the bottom of the reboiler I, and this sampling pipe 8 is connected to a composition detector 9, from which a discharge pipe 10 is connected.
is extending. Fourth, the differential pressure converter 7 and composition detector 9 are electrically connected to the computing unit II.

The operation of the above liquid level gauge will be fully explained. The density of the vapor 3 is sufficiently small compared to the density of the mixed liquid 2 and can be ignored, and the differential pressure detected by the differential pressure detector 7 connected to the detection pipe 5.6 is It shows the pressure due to the mixed liquid 2 existing at the liquid level building. The liquid level of the mixed liquid 2 can be determined from this pressure difference and the density of the mixed liquid 2, but as mentioned above [7], since the liquid density of each hydrogen isotope is different, it is necessary to know the density of the mixed liquid 2. For this purpose, it is necessary to know the composition of the mixed liquid 2. For this reason, a portion of the mixed liquid 2 is extracted from the sampling pipe 8 and the composition of the mixed liquid 2 is measured by the composition detector 9. The signal of the differential pressure converter 7 and the signal of the composition detector 9 are respectively input to the arithmetic unit I.
The signal is sent to I, where calculations are performed, and the signal is taken out as a liquid level signal 12. The frozen sample whose composition has been measured by the composition detector 9 is discharged from the discharge pipe IO.

The differential pressure type liquid level gauge described above has the following drawbacks.

(1) Gas chromatography is usually used to detect the composition of hydrogen isotopes, but it takes several tens of seconds from the time the sample is introduced to the time the composition is detected, resulting in a time delay.

(2) Samples taken for composition detection contain radioactive tritium σ) and cannot be disposed of as is, requiring post-treatment.

(3) The liquid column of each hydrogen isotope per 1 mAq differential pressure varies greatly as shown in Table 2 below.

Table 2 On the other hand, hydrogen vapor bubbles are generated due to heat intrusion from the detection pipe 5.6 and come out into the combined liquid 2, causing fluctuations in the liquid level and causing errors in the differential pressure. Taking these things into consideration, the total liquid level 4 (11 treetops) W becomes considerably worse.In order to prevent such deterioration of measurement accuracy, increase the hold rough D of the mixed liquid 2 in the reboiler 1. However, this is radioactive and high f in the inner boiler 1.
This is undesirable because it leads to an increase in the amount of tritium (1r).

(4) On the liquid level side of the differential pressure type mentioned above, the sampling pipe 8
Additionally, additional equipment such as a composition detector 9 is required, and the inertial vessel (Vt configuration) becomes complicated.

The present invention has been made to eliminate the above drawbacks.
We provide a high-precision liquid level meter that eliminates the need to measure the density of liquid, can measure the liquid level instantly with simple borrowed equipment, and eliminates problems such as post-treatment of wastewater. That is.

Hereinafter, an actual Jj7i example of the present invention will be explained with reference to FIGS. 2 and 3.

(...1 out of 4 is the reboiler of the hydrogen isotope cryogenic distillation column,
This reboiler 1 contains a mixed liquid 2 of hydrogen isotopes, above which steam 3 exists in equilibrium with the mixed liquid 2, and within the mixed liquid 2 a heater 4 is installed. − has been done. In a position near the bottom of the reboiler 1 that is always filled with the mixed liquid 2, two support shafts 211, 2 are installed from the outside.
1. .

are inserted, and these supports l1IllI211, 21
1, there is a first electric resistance wire 22 which serves as a liquid phase comparison detection end.
1 is hung. Similarly, the constant steam 3 in the reboiler 1
Two second electric resistance wires 22□ are stretched from the outside at the positions where they are in contact with. Furthermore, the first
and second lightning.

Two support shafts 213, 213 are inserted from the outside in the range in the height direction where the liquid level of the mixed liquid 2 to be measured fluctuates between the air resistance wires 22Il +222, and these supports $1121s A third electrical resistance wire 223 serving as a main detection end is stretched between +213 and 213. The first of these? 2nd and 30th resistance line 221 +
22z e 223 is the support shaft 21 as shown in FIG.
1 +211 +222 +222 1223
The detectors 241 are embedded in the +223 and -P lines 23, respectively.

It is connected to 242+243. The structure of the tip of each detection end shown in FIG. 3 described above is similar to that of a hot wire anemometer (1
The third electrical resistance wire 2, which is made of steel, is the main and external end.
The distance between the two support shafts 213 and 213 that support the anemometer 23 is considerably longer than that of a hot wire anemometer in order to ensure that the range of fluctuations in the liquid level is covered. Historically, the detector 241 t242
+243 is connected to the deductive device 25.

Explain the function of a liquid level gauge connected to a child.

1st. 2nd and 30' 1st resistance line 221.

A small constant current is passed through 22□ and 223, and the small electric current caused by this 11t is detected by the detector 241゜"2.
With +243, six rivers can be determined. This constant minute current flows through the first to third electrical resistance wires 22.
1.222. When flowing through 223, Joule heat is generated,
Heat is dissipated from each electrical resistance wire. By the way, the thermal conductivity of hydrogen isotope vapor and liquid is different as shown in the third surface pressure below, and the thermal conductivity of liquid is about five times that of vapor.

Table 3 Therefore, the amount of heat dissipated per medium length of the electrical resistance wire differs depending on whether the surrounding area of the electrical resistance wire is vapor or liquid. Temperature 1 differs depending on the part.

As a result, the electrical resistance wire takes on an electrical resistance value depending on the temperature. Such first to third electric resistance wires 22
1. The electrical resistance values of 222 p22s are measured as voltages by detectors 24 + e 24z + 243, respectively. Among these, the electrical resistance value of the third electrical resistance wire 22B is the sum of the electrical resistance value of the part in contact with the mixed liquid 2 and the -lj resistance value of the part in contact with the vapor 3, and The value depends on the liquid level. Therefore, the first electric resistance wire 22 serves as the liquid phase comparison detection end! The electrical resistance value per unit length and the electrical resistance value per unit length of the second electrical resistance wire 222 serving as the vapor phase comparison detection end are respectively input to the computing unit 25, and the computing unit 25 performs the main detection. By substituting and calculating the 'C1j resistance value per unit length on the mixed liquid 2 side and the vapor 3 side of the third electrical resistance wire 223, which is the end, the mixed liquid will be calculated regardless of the composition of the mixed liquid 2. What is the liquid level of 2′)′? It can be output as an output signal 26.

According to the liquid level statement 1 above, there is no need to determine the composition of the mixed liquid 2 by r++1], and the instantaneous liquid level is 1ll11.
Furthermore, problems such as post-treatment of the I.lithium publication solution do not occur. Further, minute changes in the liquid level can be precisely measured without increasing the hold-up fAk of the mixed liquid 20. Furthermore, since a device for detecting the composition of hydrogen isotopes is not required, the number of hydrogen isotopes is reduced to one.

In addition, in the above example, a constant current is passed through each electrical resistance wire,
Although the voltage is detected, the current value is not limited to this, and the quasi-current value may be detected by applying a constant pressure.

However, the liquid level meter of the present invention can be used not only for measuring the liquid level of hydrogen isotope liquids, but also for measuring the liquid level of other liquids, especially when the density of the liquid changes, such as mixed liquids. This is useful if you want to

As described in detail above, according to the present invention, it is possible to provide a liquid level meter that can measure the liquid level immediately with a simple device configuration, and has a precision of 6.5 mm without causing problems such as post-treatment of drained liquid. It is.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing a conventional differential pressure type level gauge, Figure 2 is a diagram showing a level gauge in an embodiment of the present invention; FIG. 3 is a front view, partially in cross section, of the tip of the detection end of FIG. 1... Reboiler, 2... Hydrogen isotope mixed liquid, 3.
...Steam, 4...Heater, 21t +212 +2
13... Support shaft, 221... l'lt l electrical resistance wire, 222... Second electrical resistance wire, 223...
iH'l: 3 Ii is air resistance wire, 23... lead wire, 241 r 242, 243... detector,
25...Measurement of performance-Ft', 26...Liquid level signal.

Claims (1)

[Claims] A first electric resistance wire stretched over the liquid phase part in the tank, a second AT electric resistance wire stretched over the gas phase part in the tank, and between these first and second electric resistance wires. a third electric resistance wire stretched in the height direction; A liquid level needle characterized in that the liquid level of the liquid is calculated by comparing the electric resistance values of the second and third electric resistance wires.