KR200191427Y1 - Equipment for leak test with tracer gas - Google Patents

Abstract

The present invention is applied to a leak tester using a tracer gas that inspects the confidentiality by using tracer gas such as ammonia, helium or halogen gas in the adiabatic space in LNG storage tank of LNG carrier and LNG receiving base. It is about.

The present invention includes a first and second insulation, double gas injection line, gas injection / discharge line, dilution tank, etc., which is a double insulation space formed outside the LNG storage tank of the LNG carrier or LNG takeover base. An apparatus for inspecting leakage of a large-capacity airtight container, comprising: a digital tracking flow meter for controlling a tracer gas to be injected at a constant rate, and a dry air (or controlling dry air or nitrogen gas to be injected at a constant rate) Nitrogen gas), the tracer gas and the dry air (or nitrogen gas) flowing from the tracer digital flow meter and the dry air (or nitrogen gas) digital flow meter are mixed with each other, but the pressure is kept constant and discharged. Pressure reducing and mixing tank, and the gas discharged from the pressure reducing and mixing tank is connected to the mixed gas injection line and at the same time gas injection / exhaust It is connected to, and is characterized in that one to be connected to the dilution tank through a vacuum pump.

Description

Leak Inspection System Using Tracer Gas {EQUIPMENT FOR LEAK TEST WITH TRACER GAS}

The present invention relates to a device for detecting leakage of a large-capacity airtight container, and more particularly, to a tracking gas such as ammonia, helium or halogen gas in an insulating space in an LNG storage tank of an LNG carrier and an LNG receiving station. The present invention relates to a leak inspection apparatus using tracer gas which performs the inspection of the confidentiality by using TRACER GAS.

In general, LNG storage tanks of LNG carriers and LNG take-up bases are made of stainless steel or invar steel called MEMBRANE to transport or store liquefied natural gas at cryogenic temperatures (-162 ℃). Is composed of double insulation space.

Therefore, the LNG storage tank is subjected to the airtight test of the heat insulating space of the storage tank surrounding the outside when the membrane is manufactured to completely maintain the airtight. This gas tightness test is a leak gas detection test using a conventional tracer gas. As the tracer gas, ammonia, helium or halogen gas as described above is used.

First, the leakage test performed by using the ammonia tracer gas, injecting the ammonia tracer gas into the adiabatic space of the storage tank, applying the reaction reagent to the outer surface, and reacting with the ammonia gas leaking through the leaked place. The leak test is performed by detecting the discoloration of the reagent. The leak test using helium or halogen gas is injected into the insulation space and helium leaks through leaks that may be present in the weld zone on the outer surface of the membrane. This is a test method that detects the location and amount of leakage of a halogen tracer gas using a helium or halogen tracer gas detector.

In addition, in order to inspect the leakage of the airtight space by injecting the tracer gas, prior to injecting the tracer gas into the airtight container, the moisture in the airtight space, that is, the insulation space of the LNG storage tank, is removed or other gas is discharged. To be done.

In addition, the process of removing moisture and discharging the gas is realized by repeating the process of injecting or discharging pure dry air (or nitrogen gas: the same below) into the airtight space several times.

Accordingly, in order to inspect the gas leakage in the hermetic space, an inspection apparatus for injecting or discharging the mixed gas of the dry air (or nitrogen gas) and the tracer gas into the hermetic space is inevitably required.

Currently, in Korea, inspection equipment for leak testing of storage tanks of LNG carriers or LNG receiving stations has been introduced and used in foreign countries such as France and Japan.

Such an inspection apparatus will be described with reference to the accompanying drawings.

1 is a schematic configuration diagram of a leak test apparatus for detecting a leak of an insulation space in a LNG storage tank of a conventional LNG carrier.

As shown, 10 is an LNG storage tank loaded on an LNG carrier, not shown, and schematically shows a front end thereof, and is configured in a polygonal shape. The outside of the LNG storage tank 10 is configured to surround the first insulation portion 11 and the second insulation portion 12 which is a heat insulating space.

In addition, the tracer gas 21 is introduced into the adjusting unit 20 through the line 32, and the drying air (or nitrogen gas) 22 to the adjusting unit 20 through the drying apparatus 23 and the line 33. It is pulled in. The adjusting unit 20 injects mixed gas (dry air + tracking gas) into the first and second heat insulating parts 11 and 12 through the bottom of the mixed gas injection line 27 and the LNG storage tank 10. The gas injection line 27 installed in the LNG storage tank 10 is connected to a plurality of inlets 14 through a gas distributor 13 so that the mixed gas is connected to the first and second insulation units 11. Disperse evenly into 12).

In addition, the gas injection / discharge line 28 connected from the adjusting unit 20 is connected to the first heat insulating part 11 and the second heat insulating part 12 through the pressure measuring device 15 and the pressure measuring device 18, respectively. Equipped with pure dry air (or nitrogen gas), or when discharging gas from the first and second heat insulating parts 11 and 12. In addition, the first heat insulating part 11 is configured such that the safety valve line 41 is connected to the safety valve tank 40 through the concentration meter 43, and the gas discharge line 29 connected from the adjusting part 20. It is configured to be connected to the ammonia dilution tank 30.

Reference numerals 16, 17, 19, 24, 25, 31 and 42 are valves and 26 are pipe connections.

On the other hand, the accompanying drawings, Figure 2 shows a detailed configuration of the adjusting unit 20, the tracking gas inlet line 32 is a tracking gas flow meter 51, dry air inlet line 33 is dry air ( Or nitrogen gas) flow meter 52, and the discharge line of the tracer gas flow meter 51 and the dry air (or nitrogen gas) flow meter 52 is laminated and connected to the mixing tank 53. The discharge line of the mixing tank 53 is connected to the pressure reduction tank 54, the discharge line of the pressure reduction tank 54 is connected to the mixed gas injection line 27 through the valve 59 and at the same time the valve 57 ) Is connected to the gas injection / discharge line 28. In addition, the gas discharge of the adiabatic space is branched from the gas injection discharge line 28 is performed in the vacuum pumps 55 and 56 through the valve 58, the gas discharge line of the vacuum pumps 55 and 56 And configured to be connected to 29.

In such a structure, the connection lines are a kind of stainless pipe.

The operation of the leak tester for detecting leakage of the insulation space of the LNG storage tank 10 configured as described above is as follows.

First, moisture (or gas) is discharged from the first and second heat insulating parts 11 and 12 of the LNG storage tank 10 using the vacuum pumps 55 and 56.

Then, in order to remove moisture (or gas) in the LNG storage tank 10, pure dry air (or nitrogen gas) 22 is the drying device 23 and the drying air (or nitrogen gas) of the adjusting unit 20. Feed into the first and second insulation sections 11 and 12 of the LNG storage tank 10 through the flow meter 52, the mixing tank 53 and the decompression tank 54, and the gas injection / discharge line 28. do.

Moisture and other gases are removed from the first and second heat insulating parts 11 and 12 of the LNG storage tank 10 by repeating the exhaust and drying air (or nitrogen gas) injection of the insulation space several times. When it is done, a test for leak detection of the hermetic space is started.

In detail, the tracer gas 21 such as ammonia and dry air (or nitrogen gas) 22 are introduced into the tracer gas flow meter 51 and the dry air (or nitrogen gas) flow meter 52 of the adjusting unit 20. do. The flow meter is a device for adjusting the injection amount of gas, and in particular, it is possible to match the mixing ratio of the tracer gas and dry air (or nitrogen gas). Therefore, the tracer gas and the dry air (or nitrogen gas), the ratio of which is determined through the flow meters 51 and 52, are injected into the mixing tank 53. The mixing tank 53 is a device for uniformly mixing the dry air (or nitrogen gas) and the tracer gas used by mixing in the tracer gas, the tracer gas and dry air (or nitrogen gas) is here Uniformly mixed at The gas mixed through the mixing tank 53 is introduced into the pressure reduction tank 54. The pressure reduction tank 54 is a device for constantly adjusting the injection pressure of the mixed gas (tracking gas + dry air).

Accordingly, the mixed gas, which is controlled under reduced pressure through the pressure reducing tank 54, is first and second through the gas distributor 13 and the plurality of inlets 14 in the LNG storage tank 10 along the mixed gas injection line 27. It is injected into the heat insulation part 11 (12). At this time, through the gas distributor 13 and the injection port 14 formed in the LNG storage tank 10, the mixed gas (lighter than the actual air) is concentrated in one direction in the first and second heat insulating parts 11 and 12. It is to be injected evenly, without the valve 59 of the adjusting portion 20 is open (OPEN), the valve 57, 58 is closed (CLOSE).

Therefore, when the gas mixture of the appropriate concentration is filled in the heat insulating part to be inspected in the first and second heat insulating parts 11 and 12 of the LNG storage tank 10 which is the hermetic container, the leakage test is started. As described above, when the ammonia tracking gas is used, the reaction reagent is applied to the outer surface of the adiabatic space of the LNG storage tank 10 and then reacted with the ammonia gas leaking through the leaked place. The leak location is detected by the presence or absence of discoloration, and when helium or halogen tracer gas is used, the helium or halogen tracer gas leaking through the leak that may be present in the welded part of the outer surface of the membrane is detected using a helium or halogen tracer gas detector. It is.

Meanwhile, vacuum pumps 55 and 56 are connected to the decompression tank 54. The vacuum pumps 55 and 56 are devices for discharging the gas introduced into the airtight space, and the LNG storage tank 10 Gases injected into the first and second heat insulating parts 11 and 12 are discharged to the ammonia dilution tank 30 through the vacuum pumps 55 and 56 and the gas discharge line 29. At this time, the valves 57 and 59 are closed, and the valve 58 is opened so that the gas filled in the first and second insulation units 11 and 12 vibrates through the gas injection / exhaust line 28. It is discharged to the pumps 55 and 56. When the ammonia dilution tank 30 uses ammonia as the tracer gas, after the inspection is completed, the ammonia dilution tank 30 is used to completely dissolve the ammonia gas discharged into the air to prevent air pollution by ammonia. When helium or halogen gas is used as the tracer gas, the tracer gas can be exhausted directly into the atmosphere without using the ammonia dilution tank 30.

In addition, the safety valve tank 40 is to be installed for the safety when the pressure of the heat insulating portion rises above a certain reference value to adjust the water level or to prevent overpressure by using lead.

However, the leak inspection apparatus using the conventional tracer gas configured as described above has the following problems.

Both the tracer gas flow meter and the dry air (or nitrogen gas) flow meter are used as a FLOAT TYPE flow meter, which may be damaged or injured due to unstable gas pressure changes, and it is difficult to adjust the gas concentration precisely due to the difficulty of fine pressure adjustment. When the tracer gas flow meter is laminated in the middle of the dry air (or nitrogen gas) flow meter discharge line and the pressure of the tracer gas used in a small amount is lower than that of the dry air (or nitrogen gas), the dry air having a relatively high pressure is used. (Or nitrogen gas) may flow back into the tracer gas flowmeter.

In addition, the conventional connection line was used by welding and assembling stainless steel pipes to each other, which not only increases the material cost but also causes welding and assembly work for installation, thereby increasing additional cost, manpower and time, and also on-site There was a problem in that it interferes with the pipeline installation of LNG carriers, delaying the entire work process.

The present invention is devised to solve the above problems, the object of the present invention is to separate the supply line of the tracer gas flow meter and the dry air (or nitrogen gas) flow meter, so that the role of the mixing tank also works in the decompression tank, Large capacity airtight containers such as LNG carriers or LNG storage tanks in LNG take-up bases, which can reduce the operational risk by using a flow meter and inject a stable and accurate amount of gas to easily control the proportion of mixed gas. The present invention provides a leak inspection apparatus using tracer gas suitable for the leakage test.

Another object of the present invention is to replace the injection, exhaust and connection lines connecting each insulation space and the control part with a non-flammable, flexible high-pressure hose, eliminating the special welding and installation work without interfering with the LNG vessel installation process, and at the same time material costs The present invention provides a leak inspection apparatus using a tracer gas to reduce the amount of gas.

The present invention for achieving the above object is the first and second heat insulating portion formed in the outside of the LNG storage tank of the LNG carrier or LNG take-up base and the first and second insulation, and the first, through the bottom surface in the LNG storage tank A mixed gas injection line for injecting a predetermined mixed gas into a second insulation unit, a gas injection / discharge line connected to the first and second insulation units, respectively, to inject or discharge gas, and the first and second insulation units An apparatus for inspecting the leakage of a large-capacity airtight container including a dilution tank for diluting the mixed gas discharged through the gas, comprising: a tracer digital flow meter for controlling the tracer gas to be injected at a constant rate; A dry air (or nitrogen gas) digital flow meter for controlling to be injected at a constant rate, the tracer digital flow meter and the dry air (or nitrogen gas) d. The pressure reducing and mixing tank which mixes the tracer gas and the dry air (or nitrogen gas) introduced from the flow meter with each other, maintains the pressure at a constant pressure, and the gas discharged from the pressure reducing and mixing tank is mixed gas injection line. It is characterized in that it is connected to the gas injection / discharge line at the same time, and further connected to the dilution tank through a vacuum pump.

1 is a schematic configuration diagram of a leak inspection apparatus for detecting a leak in a LNG storage tank of a conventional LNG carrier;

2 is a configuration diagram showing in detail the adjustment unit of FIG.

3 is a block diagram showing an adjustment unit of the leak inspection apparatus according to the present invention,

4 is a detailed configuration of the pressure reduction and mixing tank according to the present invention,

Explanation of symbols on the main parts of the drawings

20A: Adjustment part 51A: Trace gas digital flow meter

52A: Dry Air (or Nitrogen Gas) Digital Flow Meter

54A: decompression and mixing tank 55,56: vacuum pump

Hereinafter, on the basis of the accompanying drawings will be described in detail the configuration and operation of the present invention.

3 is a configuration diagram of the adjusting unit 20A of the leak test apparatus according to the present invention.

Tracking gas inlet line 32 is connected to the tracking gas digital flow meter (51A), dry air inlet line (33) is connected to the dry air (or nitrogen gas) digital flow meter (52A), and the tracking gas digital flow meter (51A) The discharge line of the dry air (or nitrogen gas) digital flow meter 52A is independently connected to the pressure reduction and mixing tank 54A. The discharge line 54-1 of the pressure reducing and mixing tank 54A is connected to the mixed gas injection line 27 through the valve 59 and to the gas injection / discharge line 28 through the valve 57. Connected. In addition, the discharge line 54-1 of the pressure reducing and mixing tank 54A is connected to the vacuum pumps 55 and 56 through a valve 58 branched from the gas injection / discharge line 28, and the vacuum The gas discharge line 29 of the pumps 55 and 56 is configured to be connected to the ammonia dilution tank 30.

Here, the tracking gas digital flow meter 51A and the dry air (or nitrogen gas) digital flow meter 52A are digital type flow meters and have a function of accurately adjusting the injection amount of gas.

Figure 4 shows a detailed configuration of the pressure reduction and mixing tank 54A according to the present invention, a plurality of through holes in the tracking gas inlet line 51-1 extending into the cylindrical body 54-2 51-2) is provided to facilitate mixing of the dry air (or nitrogen gas) with the tracer gas and to shorten the mixing time. Such a structure is intended to allow the tracer gas which is relatively smaller than the dry air (or nitrogen gas) to be evenly dispersed. In addition, a dry air inlet line 52-1 is connected to the inside of the body 54-2, and a mixed gas discharge line 54-1 is connected to a side of the body 54-2.

The operation of the leak test apparatus for detecting leakage of the adiabatic space of the LNG storage tank 10 of the present invention configured as described above is as follows.

First, only pure dry air (or nitrogen gas) 22 is introduced to remove moisture (or gas) remaining in the first and second heat insulating parts 11 and 12 of the LNG storage tank 10. In this process, the drying air (or nitrogen gas) 22 is introduced into the pressure reduction and mixing tank 54A through the drying device 23 through the drying air (or nitrogen gas) digital flow meter 52A of the adjusting unit 20A. Drying air (or nitrogen gas) discharged through the reduced pressure and the mixing tank 54A is discharged through the discharge line 54-1 and the gas injection / discharge line 28. It is injected into the 2nd heat insulation part 11 and 12, respectively.

When the dry air (or nitrogen gas) is filled in the adiabatic space, the dry air (or nitrogen gas) filled in the adiabatic space is discharged using the vacuum pumps 55 and 56.

When the exhaust and the drying air (or nitrogen gas) injection of the heat insulation space is repeated several times to remove all moisture and other gases in the first and second heat insulation portions 11 and 12, the airtight space in earnest Tests for the detection of leaks on the test are initiated.

In detail, first, a tracer gas 21 such as ammonia and dry air (or nitrogen gas) 22 are tracer digital flow meters 51A and dry air (or nitrogen gas) digital flow meters of the adjusting unit 20A. 52A). Each of the digital flowmeters 51A and 52A is injected into the pressure reduction and mixing tank 54A through the respective lines 51-1 and 52-1 by accurately adjusting the injection amount of gas. The pressure reducing and mixing tank 54A is a tank for uniformly mixing the tracer gas 21 and the dry air (or nitrogen gas) 22 and allowing the pressure of the mixed gas to be uniformly discharged. A plurality of through holes 52-1 are provided in the tracer gas injection line 51-1 so that the tracer gas 21 can be easily mixed with the dry air (or nitrogen gas) 22, and the mixing time is shortened. give. Such a structure is intended to allow the tracer gas 21 which is relatively smaller than the dry air (or nitrogen gas) 22 to be evenly dispersed. The gas thus mixed is first and second heat insulating parts through the gas distributor 13 and the plurality of inlets 14 in the LNG storage tank 10 along the discharge line 54-1 and the mixed gas injection line 27. (11) (12) is injected into. At this time, through the gas distributor 13 and the injection port 14 formed in the LNG storage tank 10, the mixed gas (lighter than the actual air) is concentrated in one direction in the first and second heat insulating parts 11 and 12. It is to be injected evenly, without the valve 59 of the adjusting portion 20 is open (OPEN), the valve 57, 58 is closed (CLOSE).

Therefore, when the gas mixture of the appropriate concentration is filled in the heat insulating part to be inspected in the first and second heat insulating parts 11 and 12 of the LNG storage tank 10 which is the hermetic container, the leakage test is started. As described above, when the ammonia tracking gas is used, the reaction reagent is applied to the outer surface of the adiabatic space of the LNG storage tank 10 and then reacted with the ammonia gas leaking through the leaked place. The leak location is detected by the presence or absence of discoloration, and when helium or halogen tracer gas is used, the helium or halogen tracer gas leaking through the leak that may be present in the welded part of the outer surface of the membrane is detected using a helium or halogen tracer gas detector. It is.

Meanwhile, vacuum pumps 55 and 56 are connected to the pressure reduction and mixing tank 54A. The vacuum pumps 55 and 56 are devices for discharging the gas introduced into the airtight space, and the LNG storage tank ( Gas injected into the first and second heat insulating parts 11 and 12 of 10 is discharged to the ammonia dilution tank 30 through the vacuum pumps 55 and 56 and the gas discharge line 29. At this time, the valves 57 and 59 are closed, and the valve 58 is opened so that the gas filled in the first and second insulation parts 11 and 12 is vacuumed through the gas injection / exhaust line 28. It is discharged to the pumps 55 and 56. When the ammonia dilution tank 30 uses ammonia as the tracer gas, after the inspection is completed, the ammonia dilution tank 30 is used to completely dissolve the ammonia gas discharged into the air to prevent air pollution by ammonia. When helium or halogen gas is used as the tracer gas, the tracer gas can be exhausted directly into the atmosphere without using the ammonia dilution tank 30.

In addition, the safety valve tank 40 is to be installed for the safety when the pressure of the heat insulating portion rises above a certain reference value to adjust the water level or to prevent overpressure by using lead.

As described above, the present invention constitutes a digital flowmeter, a pressure reduction and a mixing tank to be suitable for the leakage inspection of a large-capacity airtight container, and uses a non-flammable, flexible high pressure hose, without interrupting the pipe installation process, and special welding and installation It eliminates work, saves material costs for the use of stainless steel pipes, and has a non-flammable, flexible, high-pressure hose that makes it easy to connect each site in the field.

In addition, by using the digital flow meter, it is possible to prevent the back flow of the gas according to the pressure difference between the tracer gas and dry air (or nitrogen gas), and to adjust the amount of gas to be injected regardless of the gas injection amount. In addition, the injection rate of each gas can be easily adjusted, the target mixture can be precisely adjusted to increase the reliability of the inspection, and the cost can be reduced by preventing the loss of the flowmeter due to the unstable gas supply pressure.

In addition, a pressure reduction and mixing tank in which a conventional mixing tank and a pressure reduction tank are integrally formed is provided, which contributes to the miniaturization of the apparatus.

Claims (3)

First and second heat insulating parts which are double insulation spaces formed outside the LNG storage tank of the LNG carrier or the LNG takeover base; A mixed gas injection line for injecting a predetermined mixed gas into the first and second insulation units through a bottom surface of the LNG storage tank; A gas injection / discharge line connected to each of the first and second insulation units for injecting or discharging gas; And In the device for inspecting the leakage of the large-capacity airtight container including a dilution tank for diluting the mixed gas discharged through the first and second heat insulating portion, A tracking gas digital flow meter for controlling the tracking gas to be injected at a constant rate; A dry air (or nitrogen gas) digital flow meter for controlling dry air or nitrogen gas to be injected at a constant rate; A pressure reduction and mixing tank for mixing the tracer gas and the dry air (or nitrogen gas) introduced from the tracer digital flow meter and the dry air (or nitrogen gas) digital flow meter with each other, while maintaining a constant pressure thereof; The gas discharged from the depressurizing and mixing tank is connected to the mixed gas injection line and to the gas injection / discharge line at the same time, and to the dilution tank through a vacuum pump; Leakage inspection device using a tracking gas, characterized in that it further comprises. The method of claim 1, wherein the pressure reduction and mixing tank Cylindrical body; A dry air inlet line introduced into the body; A porous tracking gas inlet line introduced into the body and forming a plurality of through holes; And A gas discharge line formed at a side of the main body to discharge the mixed gas to the adjusting unit; Leakage inspection device using a tracking gas, characterized in that consisting of. The method of claim 1, Said mixed gas injection line, gas injection / discharge line, safety valve line and other lines, such as a non-combustible flexible high pressure hose, the leakage inspection device using a tracer gas.