JPS5979119A - Inspecting method of differential pressure type level gauge - Google Patents

Abstract

PURPOSE:To perform the inspection accurately and easily, by connecting a pressure generating means to a differential pressure-type pressure gauge. CONSTITUTION:In a step 1, a liquefied carbon dioxide gas 6 is charged into a storage tank 7 up to a level slightly higher than an overflow port 10, and it is confirmed whether a needle 15 of a differential pressure-type level gauge 8 indicates 100% or not when the liquefied gas flowed out from an overflow valve 11 is changed from white dry ice to a colorless liquefied carbon dioxide gas. In a step 2, it is confirmed whether the differential pressure-type level gauge 8 indicates zero or not when the differential pressure between the side of a liquid duct 12 and the side of a gas duct 13 is zero, that is, when the liquefied gas 6 does not exist in the storage tank 7. In a step 3, a differential pressure calculated for reduction of the level of the liquid from 100% is generated by a minute pressure generating pump 25 in the state where the side of the liquid duct 12 and the side of the gas duct 13 are cut off from each other and a cock 22 is opened to the air pressure, and it is confirmed whether the differential pressure-type level gauge indicates the value or not. Thus, the inspection is performed accurately and easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for inspecting a differential pressure type liquid level gauge used for detecting the liquid level height of a storage tank in which liquefied carbon dioxide gas is stored.

Conventionally, when inspecting a differential pressure type liquid level gauge, a pressure generating means that generates a known pressure is connected to the differential pressure type liquid level gauge to check whether the indication of the differential pressure type liquid level gauge is +E'L- or not. It was inspected. In such a test, it cannot be confirmed whether or not the actual liquid level height of the storage tank in which liquefied carbon dioxide gas is stored is correctly displayed.

In the prior art for this purpose, an inspection method as shown in FIG. 1 is used. The storage tank 1 in which liquefied carbon dioxide gas is stored includes a differential pressure type liquid level gauge 8, which will be described later, and a connecting pipe 2 that connects the top and bottom of the storage tank 1. The connecting pipe 2 has an upper f! of the storage tank 1. The cocks 3a and 3b are interposed near the JS.The cocks 4a and 4 are interposed near the bottom of the storage tank 1.
b intervenes. The connecting pipe 2 is formed with a vertical pipe portion 2a extending vertically, and a plurality of cocks 5 are disposed in the vertical pipe portion 2a in the upper F direction VC corresponding to the height of the storage tank 1.

When the liquid level height is determined by the differential pressure type liquid level gauge, the cocks 3a, 3b; Close cocks 3a, 3b; 4a, 4b,
Container 5a (5) corresponding to the liquid level determined by the differential pressure level gauge is opened. Liquefied coal gas flows out from this cock 5a, and a cock 5 installed directly above this cock 5a is opened.
When liquefied carbon dioxide gas does not flow out from the tank, it is confirmed that the differential pressure type liquid level gauge is correct. In this method, the liquefied carbon dioxide rises at the liquid level in the vertical pipe portion 2a, making it difficult to accurately measure the liquid level in the storage tank 1. In order to prevent boiling, it was necessary to keep the vertical pipe portion 2a cold. Therefore, the vertical tube portion 2a has a large diameter, which requires a large amount of cost.

In other prior art, the vertical pipe section 2 of the prior art described in frtJ
In place of a, a liquid level gauge 2b as shown in Fig. 2 is used.
Ru. A glass window is provided in the liquid level gauge 2bVcri and the elongated hole 5b extending upward. The liquid level height of the storage tank 1 can be directly read from this glass window. This liquid level gauge 2b also needs to be kept cool in the same way as the vertical pipe 64≦2a mentioned above, and a large amount of money is required to prevent the liquid level from boiling.

Is the purpose of the present invention to overcome such prior art? Ij technology/? '
,] To solve the problem and to provide a method fK for saving a differential pressure type liquid level gauge, which can easily and accurately test the accuracy of the differential pressure type liquid level gauge.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a simplified configuration diagram for explaining an inspection method of a differential pressure type liquid level gauge according to an embodiment of the present invention.

A storage tank 7Vc in which liquefied carbon dioxide gas 6 is stored is connected to a differential pressure type liquid level gauge 8. Liquefied carbon dioxide gas 6 is injected into the storage tank 7 from a tank truck 9'fx and stored therein.

To explain the operation state of the differential pressure type liquid level gauge 8, the pressure PL on the liquid pipe line 12 side drawn from the bottom 7a of the storage tank 7 to the outside, and the gas σn drawn out from the top of the storage tank 7 to the outside. Hiro・Ro 1
The liquid level H of the liquefied carbon dioxide gas calculated from the pressure difference ΔP with the pressure PG on the third side is directly read by the instruction gl-14VC. Below, a relational expression between this pressure difference ΔP and pressures PL and PG will be shown.

ΔP=:pL-PG...ill, °
, ΔP=(Ha・7'G + H@TL -HO・TG)
-(h@TG + (H-HU)・TG) ・・
・(2), ΔP = H・(TL −TG)
...+31 Here, ΔP is the pressure difference, PL is the liquid side pressure, PG is the gas side pressure, H is the liquid level height, h is the gas phase height,
HO is simple from the bottom 7a of the storage tank 7 to the indicator 14,
TL is the specific gravity of liquefied carbon dioxide, and the specific gravity of TG and P acid gas.

1. Therefore, the pressure difference ΔP in the first equation is transformed as shown in the second equation, and ? As shown in the JrJ3 formula, the liquid level height H of liquefied carbon dioxide, the specific gravity TL of liquefied carbon dioxide, and the specific gravity T of carbon dioxide
It is derived as the product of the difference between G and G. When the temperature and pressure are constant, the liquefied carbon dioxide specific gravity TL and the carbon dioxide specific gravity TG are known.

Indicator 14f/l-1 of differential pressure type liquid level gauge 8, liquid pipe line 12 and gas pipe 1i! A bellows (not shown) that deforms due to the pressure difference between the bellows and the bellows 813 is provided, and a scale plate 16 (described later) It is provided.

Among these, this bellows is temperature compensated.

Table 1 shows 1. calculated from the third formula above. The relationship between the weight of liquefied carbon dioxide, the weight of carbon dioxide, the total weight of carbon dioxide, that is, the weight of liquefied carbon dioxide, and the height of the liquid level in terms of water column.

Table 1 In this calculation, the pressure increase in the storage tank 7 is 21.5 ・k
g/Cm2G, and the liquefied carbon dioxide ratio g'i'L is 1.
012 ton/m3, coal W gas specific gravity TG'kU,
058 ton/m3. Note that this lees storage tank 7 has an inner diameter of, for example, 20 (IL) mm, and has a diameter of 27 mm.
Designed as n41f.

FIG. 4 is a front view of the scale plate 16 of the indicator 14 shown in FIG. 3. The scale plate 16 has a circular disc shape. On this scale plate 16, the total carbon dioxide limit shown in Table 1 as t'' in the outward direction of the circumferential force is graduated from ton to the first position, and the number n to the first point in the inward direction of the circumferential force is indicated.
The liquid level height calculated in terms of water column shown in the table is expressed in units of mmH20 (n), and the scale is n-.

A drive shaft 17 is provided in the center of the scale plate 16 and is removable from the bellows, and a pointer 15 (see FIG. 3) is fixed to the shaft 17 so as to be able to rotate ω1 freely.

Referring again to FIG. 3, a liquid side main valve 18 is provided at the end of the lees storage tank 7 of the liquid pipe line 12. A gas side main valve 19 is provided at the end of the storage tank 7 of the gas tank 13. The e pipe line 12 and the gas pipe line 13 are connected to the indicator 14 at a height HO from the bottom 7a of the storage 11ψ7. A bypass line 20 is provided between the liquid line 12 and the gas line 13 of the storage tank 7 connected to the indicator 14VC. A bypass valve 21 is interposed in the bypass pipe 20π. A three-way cock 22 is interposed between the gas side main valve 19 of the gas line 13 and the bypass line 20 for adjusting the pressure of the gas line 13 to the atmospheric pressure.

Mflll liquid side main valve 1B of liquid pipe line 12 and bypass pipe line 2
0 and VCFL, a three-way cock 23 is interposed.

This three-way cock 23Vc is equipped with a pressure-resistant pipe 24 that is flexible.
is not connected. This pressure-resistant pipe 24 is connected to a micro-pressure generating pump 25 as pressure generating means.

The low pressure generating pump 251 is, for example, a pneumatic manual plunger type. A pressure tube 26Vc is connected to the low pressure generation pump 25.
Therefore, the pressure gauge 27 is connected to one end of the U-shaped water column pressure gauge. Water is stored in this U-shaped pipe Vζ and is opened to the atmosphere at the dragon end of the power meter 27. Therefore, the pressure generated by the low pressure generating pump 25Vc is directly read by the pressure gauge 27 as the height of the water column.

Inspection of the differential pressure type liquid level gauge 8 in accordance with Kihatsu F#4 is carried out by the following steps 1 to 3 n4. At step 1π,
It is confirmed whether or not the display of the differential pressure type liquid level indicator 8 is correct when the storage tank 7vce and carbon dioxide gas 6 are filled to the set level. However, here, the set filling point refers to a state in which liquefied carbon dioxide gas is stored at a height corresponding to, for example, 90% of the internal volume of the storage tank 7 from the bottom 7a of the storage tank 7. Storage 4! from the bottom 7a of the storage tank 7! The overflow port 10 is opened to a point corresponding to 90% of the internal volume of the i7. At the overflow port lO,
The pipe 28 communicates with the thread flow outlet valve 11 provided on the side of the storage tank 7.The liquefied carbon dioxide gas 6 is injected from the cylinder 9 in an amount slightly larger than the set filling amount. At this time, if the overflow port valve 11 is left slightly open, the liquefied carbon dioxide injected into the container becomes dry ice from the overflow port 11, and is discharged to the outside. This dry ice is a colorless carbon dioxide gas that Japan and France stop.
When it becomes ci, the overflow 1 valve 11 is closed and the liquid g path 12 is closed.
The liquid flow source valve 18 of the gas line 13 and the gas side source valve 19 of the gas line 13 are opened, and the differential pressure type liquid 1. Directly read the scale plate 16 indicated by the pointer 15 of the indicator 14 of llJ ifl-8. This guideline 15
Does it accurately indicate 100% indicated on the scale plate 16Vc?1. In addition, it is only necessary to specify the volume within the error range due to manufacturing precision of the storage tank 7. In addition, since the liquid level a and rJIi rise immediately after the injection of the liquefied carbon dioxide gas 6, it is unstable, so after the pointer 15 becomes stable, the scale L is displayed on the board 16 and the LII reading is read.

In step 2VC, the liquid pipe line 12 side and the gas pipe line 13 side
Check the display on the differential pressure type liquid level gauge 8 when the pressure difference between the two sides is zero, that is, when there is no liquefied carbon dioxide gas 6 in the storage tank 7. When the bypass valve 21 is opened, the pressure difference becomes zero, and the pointer 15 of the indicator 14 indicates that the pressure difference converted to water column is zero. However, even when the pressure difference is zero, Assuming that carbon dioxide remains in the tank 7, the total weight of carbon dioxide is n. In addition, when opening the bypass valve 21, the side main valve 18 is first closed, and then the bypass valve 21 is opened.

In step 3, the display on the differential pressure type liquid level gauge 8 when the liquid level height of the liquefied carbon dioxide gas 6 in the storage tank 7 has decreased I7 below 100% storage is checked. Surface side main valve 18 of liquid pipe line 12
, the gas side main valve 19 of the gas pipe line 13, and the bypass valve 21
The cock 22 interposed in the gas pipe line 13 is switched to the atmospheric pressure FπI valve, and the cock 23 is switched so that the pressure-resistant pipe 24 and the pipe line 12 communicate with each other. The liquefied gas #6 is stored in the lees storage tank 7 at a certain amount, for example, 90% and 70% of the set filling amount. Calculation formula 1.
It is only necessary to generate a pressure difference by using the micro-pressure generation pump 25, so that the pointer 15 of the indicator 14 of the differential pressure type liquid level gauge 8 indicates the value of the scale plate 16σ]. Pressure gauge 27
When the difference between the pressure indicated by this indicator 14 and the eyelid indicated by this indicator 14 is, for example, 11 tonne of ±38 mmH2O, this differential pressure type liquid level gauge 8 detects the amount of liquefied carbon dioxide 6 in the 1st sulfur 7. The entire liquid level height can be measured accurately.
Before performing the inspection in step 3, a pressure difference calculated when 100% of the liquefied carbon dioxide gas 6 is stored in the storage tank 7 is generated by the drinking pressure generating pump 25, and the indicator 14 is generated correctly. Check whether υ1 is true.

According to the present invention as described in 6) above, by connecting the pressure generating means to the differential pressure type liquid level gauge, the differential pressure type liquid level gauge can be inspected accurately and easily.

[Brief explanation of the drawing]

Figure 1 is a block diagram for explaining the prior art, and Figure 2 is a parent diagram for explaining the prior art of Noh. Figure +3 is a simplified configuration diagram for explaining the inspection method of a differential pressure type liquid level gauge according to an embodiment of the present invention, and Figure 4 is a front view of the scale plate 16 of the indicator 14 shown in Figure 3. . 6... Liquefied carbon dioxide gas, 7... Storage tank, 7a... Bottom of storage tank, 8... Differential pressure type liquid level gauge, 10... Overflow port,
12...Liquid pipe line, 1:3...Gas pipe line, 14...
Indicator, 15...Upper head 1, 16...Scale plate, 2
0... Bypass I sound path, 21... Bypass valve, 22
．． 23...Three-way cock, 25...Minimum J: Generation pump, 27...Pressure gauge Agent Patent attorney Kei Shikyo Part 1 (Figure 2)

Claims (1)

[Claims] In order to detect the liquid level height of a storage tank in which liquefied carbon dioxide gas is stored, a liquid pipe line drawn out from five parts of the storage tank to the outside, and a liquid pipe line extending from the top of the storage tank to the outside are connected. A differential pressure type liquid level in which an indicator is provided in the middle of the connection with the gas pipe to be drawn out, and the liquid level height is displayed according to the difference between the pressure on the liquid pipe side and the pressure on the gas pipe side. In the inspection method for the gas meter, if the storage tank VcVi is provided with a VC overflow port at a height corresponding to the set filling amount of liquefied carbon dioxide, the gas pipe is provided with an overflow port whose height corresponds to the set filling amount of liquefied carbon dioxide gas, and the gas pipe is made to match the pressure of the gas pipe with atmospheric pressure. The H7l liquid line VC is connected to the reservoir tank and the indicator.
Liquefied carbon dioxide gas is injected into the storage tank at a pressure slightly higher than the height of the +jiI overflow port, and the state of the liquefied coal gas flowing out from the overflow port is determined, and a predetermined amount is determined. 171 When storing liquefied carbon dioxide gas to match the set filling amount, check whether the display on the differential pressure type liquid level gauge is 100%, and check whether the liquid pipe side pressure is When the difference between the pressure on the gas pipe side and the pressure on the gas pipe side is reduced to zero, check whether the display on the differential pressure type liquid level gauge is zero, and shut off the liquid pipe line drawn from the storage tank and the gas pipe line. In this state, the cock is opened, the pressure on the gas pipe side is set to atmospheric pressure, and the pressure is calculated assuming that liquefied carbon dioxide exists from the liquid pipe side to the storage tank.
``1. A method for inspecting a differential pressure type liquid level gauge, which comprises checking whether the display on the differential pressure type liquid level gauge matches the pressure when a pressure is applied.