KR20100102885A - Pressure and temperature control-monitoring system for tightness test for lng tank - Google Patents

Abstract

PURPOSE: A pressure and temperature control-monitoring system for inspecting the air-tightness of a liquefied natural gas(LNG) tank is provided to automatically control and monitor the pressure and the temperature of the LNG tank using a wire-wireless network. CONSTITUTION: An automatic valve opens and closes a pipe in order to control the flow of dry air(100), a trace gas(110), or a mixed gas. A decompression tank(130) mixes the dry air and the trace gas. Vacuum pumps(170, 171) compulsorily discharge the dry air, the trace gas, or the mixed gas from the insulated section of an LNG tank. A check valve(450) prevents the generation of contra-flow in case the mixed dry air and trace gas is introduced in the insulated section. A gas circulation pump maintains a constant concentration by circulating the mixed gas in order to prevent the separation of the dry air and the trace gas.

Description

PRESSURE AND TEMPERATURE CONTROL-MONITORING SYSTEM FOR TIGHTNESS TEST FOR LNG TANK}

The present invention relates to a device used for the leakage inspection of the non-destructive inspection to check the leakage of the large-capacity airtight container and storage tank, by forming a pressure and a vacuum pressure in the insulation zone of the LNG storage tank of LNG carrier or LNG takeover base Pressure and temperature control monitoring system for airtight inspection of LNG storage tank that checks the insulation and deformation of insulation and insulation materials and checks the insulation of insulation area using trace gas (helium, ammonia, halogen, etc.) It is about.

In general, LNG storage tanks of LNG carriers and LNG take-up bases are designed to carry or store liquefied natural gas at cryogenic temperatures (-162 ° C.) as shown in FIG. The outer wall 50 is formed and the primary and secondary insulation membranes 20 and 30 are disposed therein, and the primary and secondary insulation regions 60 and 70 include the insulation 40. It is structured.

Here, the insulating film is manufactured by assembling and welding thin sheets of stainless steel, Invar (Invar-an alloy having a very small thermal expansion coefficient composed mainly of iron and nickel) to a predetermined size. Insulation material 40 is assembled by manufacturing a glass fiber, perlite, urethane foam, etc. to a certain size, the LNG storage tank outer wall 50, the secondary insulation film 30, the secondary insulation film 30 and the primary insulation film ( 20) It serves to insulate between.

Therefore, in order to hermetically seal the insulation film of the LNG storage tank, as seen in the cross-sectional view of the LNG storage tank insulation zone of [FIG. 2], the secondary insulation zone 70 airtight inspection step produces the outer wall 50 of the LNG storage tank and the outer wall. After constructing the heat insulating material 40 around the inner circumference of 50, the secondary heat insulating film 30 is assembled and welded, and then the process for each inspection step of the second heat insulating film 30 is performed. At this time, the section between the LNG storage tank outer wall 50 and the secondary insulation film 30 is referred to as the secondary insulation zone (70).

When it is verified that there is no leakage in the secondary insulation zone 70, the insulation material 40 is re-installed on the secondary insulation film 30, the primary insulation film 20 is assembled and welded, and then the Implement the process for each inspection step. At this time, the section between the secondary insulation film 30 and the primary insulation film 20 is referred to as the primary insulation zone 60.

In addition, the inspection step is divided into the following, because each process of the inspection step has a specified pressure, the pressure and temperature control monitoring system for the airtight inspection of the LNG storage tank according to the specified pressure Pressurization and release using dry air (or nitrogen) and tracer gases (helium, ammonia, halogen). Here, the inspection step consists of a strength test, a bearing test, a mechanical stressing test, a helium leak test, a global test, and the like.

(1) Strength Test: Visual inspection of the secondary or primary insulation membranes in the LNG Cargo Tank with vacuum (approximately -800 mbar) formed in the insulation area.

(2) Bearing test: Visual inspection is to be carried out with a pressure of approximately -200 mbar in the insulation zone.

(3) Mechanical Stressing Test: The mechanical stressing test is carried out three times, injecting (pressurizing) the adiabatic zone from atmospheric pressure to +20 mbar, maintaining it for a specified time, and then reducing it back to atmospheric pressure from +20 mbar.

(4) Helium Leak Test (Helium Leak Test): After forming the adiabatic section by vacuum to about -600mbar, using the mixed gas injection hose 220 or PB1 line 391 and SB1 line 390 of FIG. Helium gas is injected (pressurized) to +20 mbar, meets the specified helium concentration (minimum 10%), and then performs helium leakage inspection using a helium leak detector on the insulation welds and seals related to the insulation area. .

(5) Global test: After helium leakage test, global test, a field of pressure change test, is conducted to verify the overall tightness of the insulation film. The temperature sensor is installed inside and outside of the LNG storage tank and connected to the recorder 181 (Fig. 1), and the insulation zone is vacuumed up to about -800 mbar, and then the gas flow and leakage detection equipment inside the insulation zone is uniform. It has a stabilization time of about 12 hours to maintain the pressure. After that, the pressure in the insulation zone and the atmosphere and the temperature inside and outside the LNG storage tank are measured and monitored for about 24 hours. Analyze the monitored pressure and temperature values to verify that the pressure change values meet the specified limits. If the specified value is exceeded, identify the cause and take corrective action, then re-run the global test. The limits of the specified pressure change value shall satisfy the following formula for the pressure change value for the 10-hour period during which the temperature value is stable among the measured 24 hours.

△ P (allowable pressure change value, mbar) ≤ 0.8 (constant) / insulation thickness (meter)

* Insulation thickness in secondary insulation zone = 0.30 meter

* Insulation thickness in primary insulation zone = 0.27 meter

In addition, the helium leakage test during the process of the inspection step is to inject dry air and tracer gas (helium, ammonia, halogen) into the insulation zone and to detect the location and amount of leakage using the tracer gas detection equipment on the outer surface of the insulation film It is a method of leak test using trace gas of nondestructive test.

On the other hand, in the case of using ammonia gas as the tracer gas 110 according to the leak test method, the leak test is to inject nitrogen gas and tracer gas (ammonia) 110 into the insulation space and apply a reagent to the insulation surface outer surface weld, There is also a method to find the location of the leak by the presence or absence of the discoloration of the reagent by the chemical reaction of the tracer gas (ammonia) (110) that leaks through the leaking place and the applied reagent, and applies the detection method according to the components of the tracer gas (110) Perform a leak test.

In addition, the global test is a leak test method using the pressure change of the non-destructive test to measure the leakage by adjusting the pressure to the temperature of the insulation space.

Figure 1 shows a pressure and temperature control monitoring system for airtight inspection of a conventional LNG storage tank.

Referring to the conventional dry air 100 injection method based on [1] as follows. The dry air 100 adjusts the MV1 valve 101 (where 'MV' is a manual valve, the same below) through the supply pipe, and adjusts the pressure reducing tank of the mixing function through the dry air flow meter 102. Reached to 130, is injected into the primary, secondary insulation zone 60, 70 of [FIG. 2] through the gas injection / exhaust line 150.

In addition, the conventional tracking gas 110 injection method will be described based on [FIG. 1]. The tracking gas 110 reaches the pressure reducing tank 130 of the mixing function through the tracking gas flow meter 112 by adjusting the MV2 valve 111 through the supply pipe, and the mixed gas injection line 140 or the gas injection / exhaust gas. Through the line 150 is injected into the primary, secondary insulation zone 60, 70 of FIG.

In addition, the conventional mixed gas injection method will be described with reference to FIG. 1 as follows. The mixed gas injection method is performed in parallel with the dry air 100 injection method and the tracking gas 110 injection method, the mixed gas mixed in the pressure reduction tank 130 of the mixing function is a mixed gas injection line 140 or gas Through the injection / exhaust line 150 is injected into the primary, secondary insulation zone 60, 70 of FIG.

In addition, a conventional vacuum forming method will be described based on [FIG. 1]. The gas of the primary and secondary insulation zones 60 and 70 of FIG. 2 is pumped through a gas injection / exhaust line 150 to AV1 160 (where 'AV' means an auto valve). The same applies to the operation of the automatic valve, the pump AV2 161 automatic valve, the pump AV3 162 automatic valve, and the operation of the vacuum pump 1 170 and the vacuum pump 2 171.

In addition, the pressure measuring method of the conventional insulation zone is as follows. The pressure of the primary and secondary insulation zones 60 and 70 of FIG. 2 is transmitted to the pressure sensor through the primary and secondary pressure measurement positions 340 and 350 of FIG. Is used to record and connect to display 180 and recorder 181.

In addition, the temperature measurement method of the conventional insulation zone is as follows. The temperature sensor is installed on the inner and outer walls 50 of the LNG storage tank to measure the temperature around the primary and secondary insulation zones 60 and 70 of FIG. 2, and the display 180 and the recorder 181. Connect to, use and record.

However, the pressure and temperature control monitoring system for the airtight inspection of the conventional LNG storage tank as shown in [1] in performing the leakage test by repeating the exhaust of the insulation zone and the injection of the dry air according to the above inspection step Causes the following problem:

The pressure and temperature control monitoring system for airtight inspection of the LNG storage tank is a heat insulation zone according to the change of the supply pressure because the supply pressure of the dry air 100 or the tracking gas 110 injected during the regulation pressure adjustment is not constant. The flow rate injected into the flow fluctuates with it, making it difficult for the operator to adjust the flow rate.

In addition, the flow rate adjustment range of the adiabatic zone is as follows. In the case of injecting the dry air 100 or the tracer gas 110 according to the design pressure of the LNG storage tank, the pressure range of the gas injection amount is 800 m3 / within -800 mbar to -100 mbar. Do not perform gas injection above h or 9 mbar / min. If the pressure in the insulation zone is from -100 mbar to atmospheric pressure or +20 mbar, the gas injection flow rate should be injected below 300 m3 / h to prevent deformation or breakage of the insulation film. And the insulation 40 of the insulation zone can also be prevented from breaking. Therefore, when a deformation or breakage of the insulation film and the insulation material 40 by mistake due to the gas injection of the worker occurs a huge replacement cost and recovery work time, physical and human resources are wasted.

In addition, if either of the dry air 100 or the tracer gas 110 is not properly supplied while injecting the mixed gas, the high-pressure gas flows back into the supply line of the gas having a low pressure, in this case, the tracer gas. If toxic or explosive at (110), a fire or death could occur.

In addition, since the mixing ratio of the dry air 100 and the tracer gas 110 cannot be easily adjusted, the tracer gas 110 may be wasted due to excessive injection of expensive tracer gas 110.

Then, after mixing and injecting the dry air 100 and the tracer gas 110, the pressure of the adiabatic section must be maintained at +10 mbar to +20 mbar during the helium leak test, wherein the mixed gas is dried air ( Since it is separated from each other by the specific gravity of the 100 and the tracer gas 110, the tracer gas 110 is additionally injected to solve this problem, and as a result, the consumption of the tracer gas 110 increases.

In addition, since the pressure indicated in the helium test procedure does not exceed +25 mbar during the helium leak test, a method using a specific gravity of water was used to maintain the pressure, but in this case, water is sucked into the adiabatic section during vacuum formation. This causes a problem that the heat insulating material 40 is lost.

In addition, since the pressure and temperature measurement data are only known to the person in charge of the pressure adjustment, the welder and other workers may not recognize whether a vacuum is formed in the insulation zone, and the welding and gouging operation on the outer wall 50 may be applied to the insulation film. As a result of the welding operation, a fire is generated in the insulation, which causes a great amount of damage, additional costs and delays in remanufacturing.

The present invention has been proposed to solve the above problems, by improving the existing system can not only automatically control and monitor the pressure and temperature for airtight inspection of LNG storage tanks, but also remote and combined with wired and wireless networks It is an object of the present invention to provide a pressure and temperature control monitoring system for airtight inspection of LNG storage tanks equipped with various functions to enable temporary work and to enhance the safety and convenience of the work manager.

Other objects and advantages of the present invention will be described below, which are not limited to the matters set forth in the claims and the disclosure of the embodiments thereof, but also to the broader ranges by means and combinations within the range readily recited therefrom. Add that it will be included.

In order to achieve the above object, the present invention, by forming a pressure and vacuum pressure in the insulation zone of the LNG storage tank to check the deformation and installation state of the insulation film and insulation and to check the airtightness of the insulation zone using the tracer gas. A pressure and temperature control monitoring system for airtight inspection of an LNG storage tank, comprising: an automatic valve for automatically opening and closing a flow of dry air, a tracking gas, or a mixed gas flowing in a pipe; Automatic flow control valve for automatically adjusting the flow rate of the drying air, the tracking gas or the mixed gas flowing in the pipe by finely adjusting the opening angle of the valve; A pressure reduction tank for mixing dry air and tracer gas; A vacuum pump forcibly discharging dry air, a tracer gas, or a mixed gas in an insulated zone of the LNG storage tank; A check valve for preventing backflow of gas generated due to a decrease in pressure on one side or breakage of a supply line when mixing dry air and a tracer gas into an adiabatic section of an LNG storage tank; A gas circulation pump which maintains a constant concentration by circulating the mixed gas in the insulation zone of the LNG storage tank to prevent separation of dry air and tracer gas; Digital signal by collecting analog signals of dry air flowing in the pipe, pressure sensor to measure the pressure of gas or mixed gas, temperature sensor to measure temperature, gas concentration to measure gas concentration, digital flow meter to measure flow rate Data collection unit for switching to; It operates according to the built-in program and controls the operation of the automatic valve, automatic flow control valve, vacuum pump or gas circulation pump based on the pressure, temperature, gas concentration and flow rate data converted into digital signals by the data collection unit. We present a pressure and temperature control monitoring system for the tightness inspection of LNG storage tanks, including a local computer, which automatically adjusts the proportion and flow rate of the flowing gas mixture.

According to the present invention, in performing the airtight inspection of the LNG storage tank, not only can automatically control and monitor the pressure and temperature, but also can be combined with the wired and wireless network to perform remote and multiple tasks, and the safety and safety of the work manager. Convenience can be enhanced.

Other effects of the present invention, as well as those described in the above-described embodiments and claims of the present invention, as well as potential effects that may occur within the range that can be easily estimated therefrom and potential advantages that contribute to industrial development It will be added that it will be covered by a wider scope.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible, even if shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the following will describe a preferred embodiment of the present invention, but the technical idea of the present invention is not limited thereto and may be variously modified and modified by those skilled in the art.

1. Premise: meaning of English abbreviation

The meaning of the English abbreviation used for convenience of explanation of the present invention is as follows.

AVG: Auto Valve Gauge

AV: Auto Valve

MV: Manual Valve

SB: Secondary Barrier

PB: Primary Barrier

HV: Helium Valve

2. Configuration of pressure and temperature control monitoring system for airtight inspection of LNG storage tank according to the present invention

The present invention forms a pressurization and vacuum pressure in the insulation zone of the LNG storage tank to check the deformation and installation state of the insulation film and insulation, and to check the air tightness of the LNG storage tank to check the tightness of the insulation zone using the tracer gas. A pressure and temperature control monitoring system designed to automatically control and monitor pressure and temperature through the interaction of data collection and local computers.

The present invention includes an automatic valve, an automatic flow control valve, a pressure reducing tank, a vacuum pump, a check valve, a gas circulation pump, a data collection unit and a local computer. Hereinafter, the functions and operations of these components will be described.

Automatic valve is a dry air, tracer gas flowing in the pipe (mixed gas injection line 140 or gas injection / exhaust line 150, etc.) of the pressure and temperature control monitoring system for the airtight inspection of the LNG storage tank according to the present invention Alternatively, it automatically opens and closes the flow of the mixed gas, and the automatic flow rate control valve automatically adjusts the flow rate of dry air, tracer gas or mixed gas flowing in the pipe by finely adjusting the opening angle of the valve. . The decompression tank mixes dry air with tracer gas.

At this time, the automatic valve plays a role of completely opening or closing the tube according to the on / off function, whereas the automatic flow rate control valve finely controls the flow rate of dry air, tracer gas or mixed gas by varying the opening angle of the valve. Can be. Both the automatic valve and the automatic flow control valve are automatically operated under the control of the local computer.

The vacuum pump plays a role of forcibly discharging dry air, tracer gas or mixed gas in the adiabatic section of LNG storage tank, and gas circulation pump circulates mixed gas in the adiabatic section of LNG storage tank to separate dry air and tracer gas. Prevents the role of maintaining a constant concentration. These vacuum pumps and gas circulation pumps also operate automatically under the control of the local computer.

The check valve serves to prevent backflow of gas generated due to a decrease in pressure on either of the two supply lines or breakage of the supply line when mixing dry air and tracer gas into the adiabatic section of the LNG storage tank. In addition to the non-return valve, the check valve functions to open or shut off itself depending on the set value when the pressure exceeds or falls below the set pressure.

Data Acquisition System (DAQ) is a data logger that collects and stores signals and a PC-based data acquisition system that acquires, quantifies and stores various data measured by sensors. Done. That is, the data collection unit is a pressure sensor for measuring the pressure of dry air, tracer gas or mixed gas flowing in the pipe, a temperature sensor for measuring the temperature, a gas concentration measuring device for measuring the gas concentration, the analog signal of the digital flowmeter for measuring the flow rate Collect and convert to digital signal.

The local computer operates according to the built-in program and controls the operation of the automatic valve, automatic flow control valve, vacuum pump or gas circulation pump based on the pressure, temperature, gas concentration and flow rate data converted into digital signals by the data collection unit. It automatically and accurately controls the ratio and flow rate of the mixed gas flowing in the pipe.

This local computer checks the automatic valve, automatic flow control valve, vacuum pump, or gas circulation pump for abnormal operation and sounds an alarm when it detects abnormal operation and sends SMS to the job manager using the SMS sending server connected to the local computer. It is possible to send 24 hours emergency response by sending out. In addition, a report is output through the printer for each process completion point of the inspection step. In addition, the collected data is stored in a set storage cycle and displayed on the monitor screen in real time, and real-time data and stored data are sent to the server using wired / wireless networks to be stored and provided to the computers of users connected to the network. Anyone who has access can check the data.

3. Improvement of pressure and temperature control monitoring system for airtight inspection of LNG storage tank according to the present invention

The present invention improves the existing system to automatically control and monitor the pressure and temperature for the airtight inspection of LNG storage tanks, as well as remote and temporary work in combination with wired and wireless networks. It is also equipped with various functions to enhance the safety and convenience of the task manager. It will be described below the characteristics of the improvement of the pressure and temperature control monitoring system for airtight inspection of LNG storage tank according to the present invention.

In the pressure and temperature control monitoring system for airtight inspection of a conventional LNG storage tank shown in FIG. 1, the signal data output from a pressure, a temperature sensor and a gas concentration meter are displayed on the display 180 and the recorder 181. Obtained and used only as a document.

However, in the case of the pressure and temperature control monitoring system for the airtight inspection of the LNG storage tank according to the present invention, the data collection unit 520 of FIG. Collect the analog signal is converted into a digital signal and transmits it to the local computer (501). Then, the local computer 501 stores the collected data and automatically controls the valves, the vacuum pumps 1, 2 (170) 171 and the gas circulation pump 172 by communication with the PLC 510, the abnormality of the equipment When the presence of abnormal operation is detected by checking the alarm sound (voice, warning light) and at the same time by sending an SMS to the task manager using the SMS sending server 550 to enable emergency response 24 hours.

Thus, the present invention is a dry air that is injected during the various pressures, that is, the regulation pressure adjustment work that occurred by the operator directly controls and monitors the pressure and temperature in the pressure and temperature control monitoring system for airtight inspection of the LNG storage tank Since the supply pressure of the 100 or the tracer gas 110 is not constant, the flow rate to be injected into the adiabatic zone is also changed according to the change in the supply pressure, which makes it difficult for the operator to adjust the flow rate. When injecting dry air 100 or tracer gas 110 according to the design pressure of the LNG storage tank in connection with the flow rate adjustment, the insulation membrane and the insulation 40 may be deformed or damaged due to the operator's gas injection. It can solve the problem of wasting physical and human resources such as huge replacement cost and recovery time. In addition, in the conventional case, since the pressure and temperature measurement data are known only to the person in charge of the pressure adjusting operation, the welder and other workers do not recognize whether a vacuum is formed in the insulation zone, and the welding and gouging operation on the outer wall 50 may be performed. The welding work on the insulation film will cause a fire in the insulation material, which would cause enormous damages and additional costs and delays in delivery due to remanufacturing. In the present invention, the alarm and output function of the local computer 501 is generated. This solved this problem.

On the other hand, the present invention is to prevent the reverse flow of the gas generated by the pressure of either one is reduced or the supply line is broken when mixing the dry air and the tracer gas into the insulating zone of the LNG storage tank, unlike the conventional case A check valve 450 is provided.

As a result, the present invention does not properly supply any one of the dry air 100 or the tracer gas 110 while injecting the conventional mixed gas so that the high pressure gas flows back into the supply line of the gas with low pressure. It solved the problem that an accident or death occurred.

In addition, the present invention is provided with a gas circulation pump 172 to circulate the mixed gas in the adiabatic zone of the LNG storage tank to prevent the separation of the dry air and the tracking gas unlike the conventional case.

As a result, the present invention can not easily adjust the mixing ratio of the conventional dry air 100 and the tracer gas 110 is excessively injected into the expensive tracer gas 110 to waste the tracer gas 110, mixed gas In order to solve the separation from each other by the specific gravity of the dry air 100 and the tracer gas 110 as time passes, the tracer gas 110 is additionally injected and as a result, the consumption of the tracer gas 110 increases. This solved the problem that had been expensive.

In addition, the local computer 501 of FIG. 5 stores the collected data in a set storage cycle and displays the data in real time, and sends the real-time data and the stored data to the server 540 using the wired / wireless network 530. In addition, the server 540 stores data and provides data to computers of users who access the network at the same time, so that anyone with access can check the data. In this case, the server 540 of FIG. 5 constantly checks the communication state with the local computer 501, and informs the administrator of the abnormality of the network by using the SMS sending server 550 when the communication state is poor. As a result, the present invention enables the remote control and monitoring of the pressure and temperature for the airtight inspection of the LNG storage tank, unlike the conventional case.

And, a user with access authority can perform all necessary operations remotely by accessing the local computer 501 with the wired / wireless network 530 of [FIG. 5], for the confidentiality inspection of the LNG storage tank according to the present invention. The local computer 501 of the pressure and temperature control monitoring system enables remote control of the local computer 501 of the pressure and temperature control monitoring system for the tightness inspection of another LNG storage tank. The pressure and temperature control monitoring system for leak tightness can be adjusted simultaneously to reduce the workforce.

4. Specific Examples

Hereinafter will be described the specific operating principle of the pressure and temperature control monitoring system for airtight inspection of the LNG storage tank according to the present invention. 4 shows a pressure and temperature control monitoring system for airtight inspection of the LNG storage tank according to the present invention. In the pressure and temperature control monitoring system for airtight inspection of the LNG storage tank according to the present invention, the local computer 501 in conjunction with the data collection unit 520, the dry air and trace gas injection logic shown in FIG. Pressure and temperature control monitoring is automatically performed according to the mixed gas injection logic shown in FIG. 7 and the vacuum forming operation logic shown in FIG. 8.

(1) Dry air injection method according to the automatic control and monitoring method

In the present invention, the method for injecting dry air 100 is as follows. When the pressure setting value 610 of [FIG. 6] is input to the local computer 501 of FIG. 5, the AGV1 valve 400 of FIG. 4, the digital flow meter D1 410 and AGV2 valve 167, AV6 valve 165 is adjusted to the LNG storage tank through the gas injection / exhaust line 150 Dry air 100 is injected into the insulation zone.

In the first and second pressure measurement positions 340 and 350 of FIG. 3, the current pressure of the insulation zone is confirmed in real time. The flow rate of the dry air 100 injected into the adiabatic zone until the set value 610 of FIG. 6 is reached is the digital flow meter of FIG. 4 that operates according to the flow control range 630 of FIG. 6. Determined by D1 410. In order to inject the flow rate determined by the digital flow meter D1 410 as described above, the local computer 501 adjusts the angles of automatic flow control valves such as the AGV1 valve 400 and the AGV2 valve 167 of FIG.

Here, the pressure adjusting operation of the thermal insulation zone selected from the thermal insulation zone setting 620 of [FIG. 6] of the primary thermal insulation zone 60 and the secondary thermal insulation zone 70 of FIG. Only when the pressure value measured at the primary and secondary pressure measurement positions 340 and 350 satisfies the adiabatic zone pressure comparison condition 640 of FIG. 6. On the other hand, when the dry air 100 is injected into the thermal insulation zone, the secondary thermal insulation zone 70 should not be higher than the pressure of the primary thermal insulation zone 60 due to the insulation film breakage protection condition 650 of FIG. . However, the section where the primary and secondary insulation zones (60) and (70) at +20 mbar at atmospheric pressure is an exception to the insulation breakage protection condition (650) and the operation is stopped unconditionally at +25 mbar.

When the data collection unit 520 of FIG. 5 collects the signals transmitted from the first and second pressure measurement positions 340 and 350 of FIG. 3 in real time, the collected pressure values are localized. The computer 501 monitors and controls the AGV1 valve (FIG. 4) by the operation of the PLC 510 from the local computer 501 when the pressure of the adiabatic zone reaches the pressure set value 610 of [FIG. 6]. 400), automatic flow control valves such as the AGV2 valve 167 and automatic valves such as the AV6 valve 165 are closed, and the completed process work of the inspection step is sent to the SMS sending server 550 to the task manager by mobile phone. The SMS is sent and a report according to the inspection result is output through the printer 540.

(2) Trace gas 110 injection method according to the automatic control and monitoring method

In the present invention, the tracking gas 110 injection method is as follows. When the pressure setting and concentration setting 710 values of [FIG. 7] are input to the local computer 501 of FIG. 5, the AGV3 valve 430 of FIG. 4 and the digital flow meter D2 ( 440, the AGV4 valve 166, and the AV6 valve 165 are adjusted to inject the tracking gas 110 into the adiabatic zone through the gas injection / exhaust line 150.

In the first and second pressure measurement positions 340 and 350 of FIG. 3, the current pressure of the insulation zone is confirmed in real time. Since only the tracer gas 110 is injected in this step, the pressure setting and the concentration setting 710 of FIG. 7 may set the concentration to 100%. The flow rate of the tracking gas 110 injected into the adiabatic zone until the pressure setting and concentration setting 710 of FIG. 7 is reached is operated according to the tracking gas flow control range 720 of FIG. 4] is determined by the digital flow meter D2 (440). In order to inject the flow rate determined by the digital flow meter D2 440, the local computer 501 adjusts the angles of the automatic flow control valves such as the AGV3 valve 430 and the AGV4 valve 166 of FIG.

When the data collection unit 520 of FIG. 5 collects the signal transmitted from the first and second pressure measurement positions 340 and 350 of FIG. 3 to the pressure sensor in real time, the local pressure is collected. 501 is to monitor and control, when the pressure in the adiabatic zone reaches the pressure of the pressure setting and concentration setting 710 of the [Fig. 6] by the operation of the PLC 510 from the local computer 501 of [Fig. 4] Automatic flow control valves such as AGV3 valve 430, AGV2 valve 166 and automatic valves such as AV6 valve 165 are closed, and the completed process work of the inspection step is sent to the SMS sending server 550 to allow the job managers to SMS to the mobile phone is sent to the report is output via the printer 540 according to the inspection result.

(3) Mixed gas injection method by automatic control and monitoring method

In order to inject the mixed gas into the adiabatic zone of the LNG storage tank, the drying air 100 and the tracking gas 110 are injected in parallel, and the mixed gas mixed in the decompression tank 130 of the mixing function is used. The mixed gas injection line 140 or the gas injection / exhaust line 150 is injected into the primary and secondary insulation zones 60 and 70 of FIG. 2.

When the pressure setting and concentration setting value 710 of FIG. 7 and the pressure work area setting 711 of the adiabatic space are made to the local computer 501 of FIG. 5, the drying air 100 of FIG. 4 is injected. The flow rate of the digital flowmeter D1 410 is adjusted by the AGV1 valve 400 and the AGV2 valve 167 of the line, and the AGV3 valve 430 and AGV4 valve 166 of the tracer gas 110 injection line are adjusted. The concentration of the mixed gas is adjusted in accordance with the tracking gas flow control range 720. At this time, the concentration of the mixed gas is primarily adjusted to the flow rate with the digital flow meter D1 (410) to the flow rate ratio with the digital flow meter D1 (410) to adjust the concentration and secondly the gas of FIG. The concentration of the digital flowmeter D1 410 may be adjusted using the concentration value measured by the concentration meter 480 to increase and decrease the concentration.

Here, when the mixed gas is injected, the mixed gas injection hose 220 separated into several lines from the gas distributor 210 through the mixed gas injection line 140 and the HV1 valve 200 of FIG. 3. Inject the mixed gas into the bottom of the LNG storage tank using the method, or the gas injection / exhaust line 150, the secondary insulation zone 70 uses the SB1 line 390 and the primary insulation zone 60 ) May use a method using the PB1 line 391.

On the other hand, if either of the dry air 100 or the tracer gas 110 is not properly supplied in the process of injecting the mixed gas, a phenomenon in which a high supply pressure gas flows back into a supply line of a gas having a low supply pressure In order to prevent this, the present invention installed a check valve 450 of FIG. 4 to prevent such a backflow phenomenon. Here, the check valve 450 of FIG. 4 is a device that allows gas in a pipe to flow in only one direction.

When the mixed gas is injected and the pressure of the insulation section is maintained at +10 mbar to +20 mbar during the helium leak inspection step, the mixed gas is dried air 100 and the trace gas due to the specific gravity difference of the gas element over time. 110). In order to solve this problem, the trace gas 110 was additionally injected in the related art, so that the consumption of the trace gas was large, and in the case of the present invention, the gas circulation pump 172 of FIG. By continuously circulating the gas, the concentration of the mixed gas in the adiabatic zone can be evenly distributed throughout, and the state can be maintained continuously.

The operation principle of the gas circulation pump 172 is as follows. When the gas in the adiabatic zone is sucked through the gas injection / exhaust line 150 of FIG. 4 and the gas circulation mode is selected by the local computer 501 of FIG. 5, the gas circulation pump 172 of FIG. 4 is selected. And the AV1, 4, 5 valves 160, 163 and 164 are opened and exhausted through the mixed gas injection line 140, thereby circulating the mixed gas.

(4) Overpressure prevention device for gas injection

On the other hand, when the drying air 100 or the tracking gas 110 is injected, the maximum pressure of the adiabatic space is not to exceed +25 mbar. To this end, a conventional method using the specific gravity of water is used, but water is sucked into the adiabatic section when vacuum is formed, and according to the present invention, a check valve (PB2 line 381 and SB2 line 380 of FIG. 3) is used. 451) prevents the problem that water is sucked into the insulation zone from the overpressure preventing device 455 during the vacuum operation of the insulation zone.

On the other hand, when the pressure of the secondary insulation zone 70 rises above the vacuum pressure of the primary insulation zone 60 when the primary and secondary insulation zones 60 and 70 of FIG. 2 are in a vacuum state. The check valve 370 of FIG. 3 is opened to protect the secondary thermal insulation film 30 of FIG. 2 by allowing the pressure of the primary insulation region 60 and the secondary insulation region 70 to be the same. .

(5) Vacuum forming method by automatic control and monitoring method

Vacuum forming method of the insulation zone of the LNG storage tank in the present invention is as follows. When the pressure setting value 610 of FIG. 6 is input to the local computer 501 of FIG. 5 and the adiabatic zone setting 620 is selected, the pressure setting value 610 in the injection / vacuum work selection section 660 is selected. ) And the pressure of the selected adiabatic zone setting 620 and the pressure setting value 610 is low, the local computer 501 is the first and second of FIG. 2 by the vacuum forming work logic of FIG. Vacuum forming is performed on the heat insulation zone selected in the heat insulation zone setting 620 among the primary heat insulation zones 60 and 70.

That is, the local computer 501 of FIG. 5 controls the PLC 510 to operate the first and second vacuum pumps 170 and 171, and the vacuum pump temperature sensor 490 of FIG. 8) reaches the vacuum pump preheating temperature 810 of FIG. 8, opens the vacuum pumps AV2 and AV3 valves 161 and 162 and the vacuum pump AV1 valve of FIG. Through the forced discharge of gas in the thermal insulation zone through the start of vacuum formation.

On the other hand, the local computer 501 and the vacuum pumps AV2, AV3 valves 161, 162 of [Fig. 4] when the pressure of the heat insulation section during the vacuum forming operation is equal to the pressure set value 610 of [Fig. 6]. Closing the vacuum pump AV1 valve stops gas flow in the pipe and stops the first and second vacuum pumps 170 and 171. And the completed process work content of the inspection step is sent to the SMS sending server 550, SMS is sent to the mobile phone to the job manager, the report according to the inspection result is output through the printer 540.

(6) Promote safety and convenience of work manager

In the past, pressure and temperature measurement data were known only to the person working on the pressure adjustment or had to contact the other party by radio or telephone. For this reason, the welder and other workers are not aware of the vacuum formation of the insulation zone, and the insulation is fired due to the welding and gouging of the outer wall 50 or the welding of the membrane. There was a problem of delayed delivery due to re-production.

In order to prevent this, the SMS is automatically sent to all persons including the person who performs the inspection of each inspection step such as the ship owner and the ship owner by using the SMS sending server 550 of FIG. By sending them, they can quickly obtain pressure and temperature measurement data.

On the other hand, the person who has the authority to access the server 540 of FIG. 5 connects to the server 540 by using a computer connected to the server 540 and the network to check the pressure and temperature data of each tank and ship of the LNG carrier. Not only can you check in real time, you can also check the historical data, and you can check the report immediately after the digital signature, you do not have to go to the signer with the report as before.

The above description is merely illustrative of the technical idea of the present invention, and various modifications, changes, and substitutions may be made by those skilled in the art without departing from the essential characteristics of the present invention. will be. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by the embodiments and the accompanying drawings. . The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Figure 1 shows a pressure and temperature control monitoring system for airtight inspection of a conventional LNG storage tank.

2 is a cross-sectional view of the LNG carrier storage tank insulation zone.

3 shows the dry air and mixed gas injection lines in the LNG carrier storage tank.

4 shows a pressure and temperature control monitoring system for airtight inspection of the LNG storage tank according to the present invention.

FIG. 5 illustrates in more detail the 'pressure and temperature control monitoring unit' and 'server and network' of [FIG. 4].

6 shows the drying air and tracer gas injection logic according to the present invention.

7 illustrates a mixed gas injection logic in accordance with the present invention.

8 shows the vacuum forming operation logic according to the present invention.

Claims (5)

Pressure and temperature for airtightness inspection of LNG storage tank which checks the insulation and insulation of insulation layer by using tracer gas by checking the deformation and installation state of insulation film and insulation by forming pressurization and vacuum pressure in insulation area of LNG storage tank. As a control monitoring system, Automatic valve for automatically opening and closing the flow of dry air, tracer gas or mixed gas flowing in the pipe; Automatic flow control valve for automatically adjusting the flow rate of the drying air, the tracking gas or the mixed gas flowing in the pipe by finely adjusting the opening angle of the valve; A pressure reduction tank for mixing dry air and tracer gas; A vacuum pump forcibly discharging dry air, a tracer gas, or a mixed gas in an insulation region of the LNG storage tank; A check valve for preventing backflow of gas generated due to a decrease in pressure on one side or breakage of a supply line when mixing dry air and a tracer gas into an adiabatic section of an LNG storage tank; A gas circulation pump which maintains a constant concentration by circulating the mixed gas in the insulation zone of the LNG storage tank to prevent separation of dry air and tracer gas; Digital signal by collecting analog signals of dry air flowing in the pipe, pressure sensor to measure the pressure of gas or mixed gas, temperature sensor to measure temperature, gas concentration to measure gas concentration, digital flow meter to measure flow rate A data collection unit for switching to; And It operates according to the built-in program and controls the operation of the automatic valve, automatic flow control valve, vacuum pump or gas circulation pump based on the pressure, temperature, gas concentration and flow rate data which are converted into digital signals by the data collection unit. Pressure and temperature control monitoring system for leak tightness inspection of LNG storage tank including local computer that automatically adjusts the ratio and flow rate of mixed gas. The method of claim 1, The local computer checks the automatic valve, automatic flow control valve, vacuum pump or gas circulation pump for abnormal operation and sends an SMS to the job manager by using an SMS sending server connected to the local computer. Pressure and temperature control monitoring system for airtight inspection of LNG storage tank, characterized in that to enable 24 hours emergency response. The method of claim 1, The local computer automatically sends SMS to all persons including the person who performs the inspection at each inspection stage such as ship owners and classmates and other related persons by using SMS sending server connected to the local computer at every process of inspection stage. Pressure and temperature control monitoring system for leak tightness inspection of the LNG storage tank, characterized in that to quickly learn. The method of claim 1, The local computer pressure and temperature control monitoring system for the airtight inspection of the LNG storage tank, characterized in that for outputting a report through the printer at the completion of each process of the inspection step. The method of claim 1, The local computer stores the collected data in the set storage cycle and displays it on the monitor screen in real time, and sends the real-time data and the stored data to the server using wired / wireless networks to be stored and stored on the computers of users connected to the network. Pressure and temperature control monitoring system for confidentiality inspection of the LNG storage tank, characterized in that anyone who has access to check the data to provide.

Images