KR101594247B1

KR101594247B1 - A Maintenance System of Liquid Storage Tank

Info

Publication number: KR101594247B1
Application number: KR1020140072149A
Authority: KR
Inventors: 문진국; 김재신; 김재을; 박진상
Original assignee: 현대중공업 주식회사
Priority date: 2014-06-13
Filing date: 2014-06-13
Publication date: 2016-02-17
Also published as: KR20150143939A

Abstract

The present invention relates to a liquid storage tank management system, comprising: a liquid storage tank comprising a gap located between a barrier and an insulating layer; A nitrogen supply line for supplying nitrogen from the nitrogen storage tank to the gap; A gas discharge line for discharging gas from the gap; A sensor provided on the gas discharge line; And a control unit for calculating a concentration of nitrogen through the sensor, wherein the control unit controls the flow rate of nitrogen circulating through the gap.
The liquid storage tank management system according to the present invention maximizes the heat insulation performance of the liquid storage tank and circulates the stored liquid quickly by circulating nitrogen in the gap between the barrier wall of the liquid storage tank and the heat insulating layer, It is possible to prevent damage and destruction of the liquid storage tank and to maximize the reliability of the storage transportation.

Description

[0001] The present invention relates to a liquid storage tank,

The present invention relates to a liquid storage tank management system.

Natural gas is transported in the form of gas through land or sea gas pipelines or liquefied in the form of Liquefied Natural Gas or Liquified Petroleum Gas and stored in LNG transport or LPG transport It is transported to a remote consumer.

Liquefied natural gas is obtained by cooling natural gas at a temperature of minus 163 degrees Celsius, which is the cryogenic temperature, and its volume is reduced to about 1/600 of that of natural gas, making it well suited for long distance transportation through the sea.

LNG carrier for loading liquefied natural gas to land area by carrying liquefied natural gas to sea, and LNG carrier after landing at land demand by carrying LNG to sea, and unloading it as natural gas LNG RV (Liquefied Natural Gas Regasification Vessel) includes a cryogenic storage tank of liquefied natural gas.

Recently, the demand for floating floating structures such as LNG FPSO (Floating, Production, Storage and Offloading) and LNG FSRU (Floating, Storage and Regasification Unit) is gradually increasing, and LNG carrier or LNG RV As shown in Fig.

LNG FPSO is a floating marine structure that is used to directly liquefy natural gas extracted from a gas well and to store it in a storage tank and transfer LNG stored in this storage tank to LNG transport if necessary. In addition, the LNG FSRU is a floating type of floating structure that stores LNG unloaded from LNG carrier at sea, stores it in a storage tank, vaporizes LNG if necessary, and supplies it to the customer demanded on land.

In this way, a storage tank for storing liquefied gas such as LNG is installed in a marine structure such as an LNG carrier, LNG RV, LNG FPSO, and LNG FSRU that transports or stores a liquefied gas such as LNG.

These LNG storage tanks are classified according to their form and function. Depending on the type, there are independent tanks (SPB) and membrane tanks (GTT Mark 3, GTT NO 96). Independent tanks are classified into A, B and C types according to IMO standards.

SPB (Self-support Prismatic shape IMO type-B) tanks of independent tanks are rectangular. The SPB tank was developed by IHI of Japan in 1982 by developing a square (rectangular) tank. The aluminum tanks were placed on the thermal insulation support, and the shape of the tanks was freely designed according to the shape of the hull. It can be manufactured externally and installed on a ship.

In addition, it has a relatively advantage in terms of structural stability compared with the membrane type, and is resistant to sloshing, and the insulation system is exposed to the outside of the tank, which is advantageous in that an operator can easily maintain it.

In the event of leakage of stored stock in such SPB tanks, the properties of the cryogenic reservoir will damage the tank and severely damage the external equipment. Therefore, in recent years, a lot of research and development have been conducted to prevent leakage of the tank.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid storage tank management system for circulating nitrogen between a barrier wall of a liquid storage tank and a heat insulating layer to quickly grasp the leakage of the stored liquid. will be.

A liquid storage tank management system according to an embodiment of the present invention includes: a liquid storage tank including a gap positioned between a barrier and a heat insulating layer; A nitrogen supply line for supplying nitrogen from the nitrogen storage tank to the gap; A gas discharge line for discharging gas from the gap; A sensor provided on the gas discharge line; And a control unit for calculating a concentration of nitrogen through the sensor, wherein the control unit controls the flow rate of nitrogen circulating through the gap.

Specifically, when the concentration of nitrogen is decreased to a predetermined concentration or less, the control unit may supply a larger amount of nitrogen to the gap than the amount of nitrogen supplied when the concentration exceeds the predetermined concentration.

Specifically, a buffer tank for storing the nitrogen; And a vent device for venting the nitrogen.

Specifically, when the pressure of the support space between the liquid storage tank and the inner wall of the hull increases due to the nitrogen discharged from the gap, the nitrogen is stored in the buffer tank, .

Specifically, the apparatus may further include a nitrogen separator provided on the gas discharge line and separating nitrogen from gas discharged from the gap.

Specifically, when the concentration of nitrogen discharged from the gap decreases to a predetermined concentration or less, the control unit may return the separated material from the nitrogen separator to the liquid storage tank.

More specifically, the controller may further include an alarm unit for alerting the operator if the concentration of nitrogen discharged from the gap decreases below a preset concentration.

The liquid storage tank management system according to the present invention maximizes the heat insulation performance of the liquid storage tank and circulates the stored liquid quickly by circulating nitrogen in the gap between the barrier wall of the liquid storage tank and the heat insulating layer, It is possible to prevent damage and destruction of the liquid storage tank and to maximize the reliability of the storage transportation.

1 is a conceptual diagram of a liquid storage tank management system according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The objects, particular advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. It should be noted that, in the present specification, the reference numerals are added to the constituent elements of the drawings, and the same constituent elements have the same numerical numbers as much as possible even if they are displayed on different drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1, a liquid storage tank management system 1 according to an embodiment of the present invention includes a liquid storage tank 10, an inner wall 20, a buffer tank 40, a nitrogen storage tank 50, A Drip Tray 60, a sensor 80, a nitrogen separator 90, a control unit 100, and an alarm unit 110.

The liquid storage tank 10 may store a storage, preferably a liquefied gas, in the interior 14, and the liquefied gas may include all of the gaseous fuels generally stored in a liquid state, such as LNG or LPG, ethylene, ammonia, And may be expressed as a liquefied gas for the sake of convenience when the liquid is not in a state of being heated or pressurized.

The liquid storage tank 10 may be a stand-alone tank, preferably a SPB type liquid storage tank, and may include a barrier 11, a gap 12, and a thermal barrier layer 13.

The barrier 11 can be in contact with the reservoir 15 stored in the liquid storage tank 14 and can absorb the impact. The barrier 11 may be made of a low temperature resistant alloy such as aluminum alloy, SUS, and 9% nickel.

The gap 12 may be formed between the barrier 11 and the heat insulating layer 13 and the barrier 11 and the heat insulating layer 13 may be spaced apart from each other by a predetermined distance. The gap 12 is generated by a pad (not shown) having a plate shape of a constant thickness being disposed in close contact with a stud bolt (not shown) for fixing the barrier 11 and the heat insulating layer 13 .

That is, the gap 12 may be formed by a pad so as to generate a gap in which the barrier 11 and the heat insulating layer 13 are spaced apart from each other. The gap 12 may be approximately 2 to 8 mm and preferably 5 mm.

The gap 12 can be utilized as a ventilation space and can also be used as a passage for the leaked storage 15 when the storage 15 leaks due to damage and breakage of the barrier 11. [

The leaked storage material 15 joins and dies in a drip tray 60 for temporarily storing the leaked storage material 15. Conventionally, a measurement sensor is mounted on the drip tray 60, And it was confirmed that it leaked.

However, it takes a considerable amount of time (usually 20 days) for the leaked storage 15 to move to the drip tray 60, so that the leakage can not be recognized quickly. As a result, the maintenance time point of the liquid storage tank 10 There was a problem to be delayed.

In addition, since the maintenance time of the liquid storage tank 10 is delayed, there is a fear that a large amount of the stored liquid 15 will flow out, and a small crack can not be repaired at an early stage, which may lead to breakage of the liquid storage tank 10.

Further, when the stored liquid 15 of the liquid storage tank 10 leaks, the equipment (not shown) or the inner wall 20 may be damaged by the leaked stored liquid 15, (15) There is a problem that the safety and reliability of transportation are reduced.

Therefore, in the embodiment of the present invention, the gap 12 receives nitrogen from a nitrogen storage tank 50 to be described later, continuously discharges the supplied nitrogen into a holding space 30, So that the entire gap 12 can be circulated.

By circulating nitrogen in the gap 12, the nitrogen is discharged to the outside together with the vaporized stock 15 of the stored product 15, and it is quickly judged whether or not the gas is leaked through the sensor 80 to be described later There is an effect that can be.

Further, it is possible to maximize the heat insulation performance of the liquid storage tank 10 through the nitrogen gas at a cryogenic temperature rather than the insulation through the air, and at the same time, the leak of the stored product 15 can be quickly grasped. It is possible to prevent damage and destruction of the liquid storage tank 10 and further to maximize the reliability of the transportation of the stored product 15. [

The heat insulating layer 13 is provided outside the barrier 11, and a plurality of hexagonal heat insulating panels (not shown) (not shown) can be attached successively. The heat insulating layer 13 can prevent the heat from being transmitted to the storage 15 contained in the liquid storage tank 10 in the above-described structure.

The heat insulating layer 13 may have any predetermined thickness in order to block heat transfer from the outside. The heat insulating layer 13 is filled with a heat insulating material having elasticity even at a very low temperature between a plurality of the heat insulating panels in order to prevent the generation of stress in the heat insulating layer in accordance with shrinkage and tensile of the barrier 11 along with the cryogenic storage 15 .

The insulating layer 13 may be fixed to the barrier 11 together with a washer (not shown) by stud bolts or screws (not shown) or the like. At this time, the heat insulating layer 13 may be fixed so as to form a gap, that is, a gap 12, without being completely in close contact with the barrier 11.

The inner wall 20 is a hull provided inside a hull (not shown), and the hull can be a double hull having an outer hull and an inner hull.

The inner wall 20 may be in the form of a support space 30 for the liquid storage tank 10 to be positioned inside the hull and may be formed in any shape. A support 70 is provided on the inner wall 20 so that the liquid storage tank 10 located in the support space 30 can be supported by the hull.

The buffer tank 40 may temporarily store nitrogen discharged from the support space 30. [ The buffer tank 40 can introduce the nitrogen gas filling the support space 30 for regulating the pressure of the support space 30 when the pressure of the support space 30 becomes equal to or higher than the predetermined pressure.

The embodiment of the present invention may further include a nitrogen discharge line 41 and a vent line 42.

The nitrogen discharge line 41 may connect the support space 30 and the buffer tank 40 and may include a nitrogen discharge valve 43. The nitrogen discharge valve 43 can regulate the discharge amount of nitrogen according to the opening degree control of the nitrogen discharge valve 43.

The vent line 42 is branched at the nitrogen discharge line 41 and can be connected to the outside of the hull, and can have a vent valve 44. The vent line 42 controls the opening degree of the vent valve 44 to control the opening degree of the nitrogen supplied to the buffer tank 40 so as to control a part of the nitrogen supplied to the buffer tank 40, It can be discharged to the outside.

The vent line 42 may restrict the introduction of nitrogen into the buffer tank 40 and discharge the entire amount of the nitrogen gas discharged from the support space 30 to the outside of the hull when the buffer tank 40 exceeds the storage capacity have.

At this time, the vent line 42 is not limited to being connected to the outside of the hull, and may be connected to a gas combustion device (not shown). The vent valve 44 can control the amount of nitrogen vent according to the opening degree of the vent valve 44.

The nitrogen storage tank 50 stores nitrogen supplied to the support space 30 or the gap 12. The nitrogen storage tank 50 may be a storage tank in the form of a pressure vessel for storing nitrogen in a liquid state and for storing cryogenic liquid nitrogen.

At this time, the nitrogen storage tank 50 may include a pump (not shown) and a heat exchanger (not shown) so that the liquid nitrogen may be phase-changed into a gaseous state and supplied to the support space 30 or the gap 12 . The temperature of nitrogen can be changed by a heat exchanger.

In the embodiment of the present invention, a nitrogen supply line 51, a gap supply line 52, and a gap discharge line 53 may be further included.

The nitrogen supply line 51 may supply the nitrogen from the nitrogen storage tank 50 to the support space 30 by connecting the nitrogen storage tank 50 and the support space 30. At this time, a nitrogen supply valve 54 is provided in the nitrogen supply line 51 so that the supply amount of nitrogen can be adjusted according to the opening degree control of the nitrogen supply valve 54.

The gap supply line 52 may branch off from the nitrogen supply line 51 and connect with the gap 12 to supply nitrogen from the nitrogen storage tank 50 to the gap 12. At this time, the nitrogen supply valve 54 is provided at a branch point (not shown) to adjust the opening amount of the nitrogen supply valve 54 so that the nitrogen supply amount into the support space 30 and the nitrogen supply amount into the gap 12 Can be adjusted.

The gap discharge line 53 connects the gap 12 and the support space 30 to discharge the nitrogen flowing in the gap 12 into the support space 30. [ A sensor 80 and a nitrogen separator 90, which will be described later, may be connected to the gap discharge line 53.

The Drip Tray 60 receives the storage 15 leaking from the barrier 11 when leakage of the storage 15 occurs in the barrier 11 and drains or discharges it to the outside Device.

The drip tray 60 may be disposed between the inner wall 20 and the thermal insulation layer 13 to receive a storage 15 that may leak from the barrier 11 of the liquid storage tank 10. The drip tray 60 may be installed at the bottom (not shown) or the side (not labeled) of the barrier 11. [

The sensor 80 measures the concentration of nitrogen from a mixed gas of nitrogen or nitrogen and vaporized stock 15 provided in the gap discharge line 53 to exit the gap 12. The sensor 80 may be provided at a front end of a nitrogen separator 90 to be described later. The sensor 80 may measure the temperature or the flow rate of the gas discharged from the gap 12 without limitation to the nitrogen concentration.

The sensor 80 may transmit the measured value to the control unit 100 by wire or wirelessly.

The nitrogen separator 90 is provided on the gap discharge line 53 and is capable of separating nitrogen from the gas exiting the gap 12. Where the gas may be a mixed gas of nitrogen and vaporized stock 15.

The nitrogen separator 90 may be installed at a rear end of the sensor 80. When the concentration of nitrogen measured by the sensor 80 is reduced to a predetermined concentration or less, And can return to the liquid storage tank (10).

The nitrogen separator 90 can receive a driving signal transmitted from the control unit 100 and can be driven only when the concentration of nitrogen measured by the sensor 80 decreases below a preset concentration through the control unit 100 have.

In the embodiment of the present invention, the storage return line 55 may be further included. The storage return line 55 may connect the nitrogen separator 90 and the liquid storage tank 10 to supply the storage supplied from the nitrogen separator 90 to the liquid storage tank 10.

The storage return line 55 may be provided with a storage return valve (not shown), and the storage return amount may be adjusted according to the opening degree of the storage return valve.

The control unit 100 calculates the concentration of nitrogen through the sensor 80 and controls the flow rate of nitrogen circulating to the gap 12. [ Specifically, when the concentration of nitrogen is reduced to a predetermined concentration or less, the controller 100 may supply the amount of nitrogen to the gap 12 in an amount greater than the amount of nitrogen supplied when the concentration exceeds the predetermined concentration.

In the event of damage to the barrier 11, the reservoir 15 leaks from the barrier 11 and a portion of the leaked deposit 15 is vaporized and mixed with the nitrogen gas circulating through the gap 12 And is discharged from the gap 12. Thus, when the nitrogen gas and the vaporized storage 15 are mixed and discharged in the gap 12, the concentration of nitrogen discharged from the gap 12 decreases to a predetermined concentration or less.

That is, when the concentration of nitrogen discharged from the gap 12 decreases below a preset concentration, it means that the barrier 11 is damaged and the stored substance 15 is leaking.

Therefore, in the embodiment of the present invention, the amount of nitrogen supplied to the gap 12 is made larger than the amount of nitrogen supplied when the predetermined concentration is exceeded, so that the leaked storage 15 can not be discharged from the barrier 11 have.

As the flow rate of the nitrogen gas flowing through the gap 12 increases, the leakage flow of the storage material 15 to be discharged from the barrier 11 can be prevented, and leakage of the storage material 15 can be prevented.

When the pressure of the support space 30 between the liquid storage tank 10 and the inner wall 20 of the hull is increased due to the nitrogen discharged from the gap 12 to be higher than the predetermined pressure, (40) or vented to vent device (44).

Nitrogen is continuously supplied to the support space 30 through the nitrogen circulation of the gap 12. In addition, since the support space 30 is basically filled with nitrogen, the internal pressure of the support space 30 is increased due to the nitrogen continuously supplied for the circulation of the gap 12. The nitrogen can be supplied to the buffer tank 40 or the vent device 44 when the internal pressure of the support space 30 is increased beyond the predetermined pressure in order to prevent the internal pressure of the support space 30 from rising

The control unit 100 may return the stored separated material from the nitrogen separator 90 to the liquid storage tank 10 when the concentration of nitrogen discharged from the gap 12 decreases below a preset concentration.

As described above, when the concentration of nitrogen discharged from the gap 12 decreases below a preset concentration, the storage 15 leaks from the barrier 11. Therefore, in order to collect the vaporized storage 15 in the gas discharged from the gap 12, the control unit 100 operates the nitrogen separator 90 to recover the nitrogen and the vaporized storage 15 The separated and separated stock 15 can be returned to the liquid storage tank 10.

The alarm unit 110 can warn a worker (not shown) when the concentration of nitrogen discharged from the gap 12 decreases below a preset concentration.

The alarm unit 110 can receive a driving signal from the control unit 100 by wire or wireless and send a signal to the operator that the stored object 15 is leaking by means of a warning lamp, .

The liquid storage tank management system 1 according to the present invention can circulate nitrogen in the gap 11 between the barrier 11 and the heat insulating layer 13 of the liquid storage tank 10, It is possible to maximize the adiabatic performance and at the same time to quickly grasp the leakage of the stored product 15 to thereby prevent the damage and destruction of the liquid storage tank 10 and to maximize the reliability of the transportation of the stored product 15. [ There is an effect that can be.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the same is by way of illustration and example only and is not to be construed as limiting the present invention. It is obvious that the modification and the modification are possible.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1: Liquid storage tank management system 10: Liquid storage tank
11: barrier 12: gap
13: Insulating layer 14: Inside liquid storage tank
15: Storage 20: Inner wall (Hull)
30: Hold Space 40: Buffer tank
41: nitrogen discharge line 42: vent line
43: nitrogen discharge valve 44: vent valve
50: nitrogen storage tank 51: nitrogen supply line
52: gap supply line 53: gap discharge line
54: Nitrogen supply valve 55: Storage return line
60: Drip tray 70: Support
80: sensor 90: nitrogen separator
100: control unit 110: alarm unit

Claims

A liquid storage tank including a gap positioned between the barrier and the insulating layer;
A nitrogen supply line for supplying nitrogen from the nitrogen storage tank to the gap;
A gas discharge line for discharging gas from the gap;
A sensor provided on the gas discharge line; And
And a control unit for calculating the concentration of nitrogen through the sensor,
Wherein,
Controlling the flow rate of nitrogen circulating through the gap,
Wherein the amount of nitrogen supplied to the gap is greater than the amount of nitrogen supplied when the concentration of nitrogen exceeds the predetermined concentration when the concentration of nitrogen is reduced to a predetermined concentration or less.

delete

The method according to claim 1,
A buffer tank for storing the nitrogen; And
Further comprising a vent device for venting said nitrogen.

The apparatus of claim 3,
When the pressure of the support space between the liquid storage tank and the inner wall of the hull increases due to nitrogen discharged from the gap,
Wherein the nitrogen is stored in the buffer tank or discharged to the vent apparatus.

The method according to claim 1,
Further comprising a nitrogen separator disposed on the gas discharge line and separating nitrogen from gas exiting the gap.

6. The apparatus of claim 5,
And returning the separated material from the nitrogen separator to the liquid storage tank when the concentration of nitrogen discharged from the gap decreases to a predetermined concentration or less.

The method according to claim 1,
Further comprising an alarm unit for alerting the operator when the concentration of nitrogen discharged from the gap decreases below a preset concentration.