KR100980269B1 - Safety system and method for cryogenic liquid leakage - Google Patents

Abstract

The present invention, when detecting the leakage of cryogenic liquid due to damage to the cargo hold barrier, by forming ice according to the purging of the solidified gas to prevent the leakage site, it is possible to quickly protect the cargo and hull in response to leakage accident Cryogenic Liquid Leakage Prevention System and Method

Cryogenic liquid leak prevention system of the present invention is the empty space (C1) between the primary barrier 50 and the secondary barrier 67 of the cargo hold for cryogenic liquid 10 storage is monitored by the integrated control system 130 To be installed in a vessel in which the inert gas lines 112 and 113 extend toward the empty space C2 between the secondary barrier 67 and the hull inner wall 1, and are connected to the inert gas lines 112 and 113. It is connected to the solenoid type switching valve (V1), the solidified gas line 122 piped to the switching valve (V1) to supply the solidified gas toward the inert gas line (112, 113), and the solidified gas line 122 Leak prevention controller 140 connected to the solidification gas storage means 120 and the switching valve V1 storing the solidified gas and performing line switching control of the switching valve V1 in response to detection of leakage of the cryogenic liquid 10. It includes.

Vessel, Integrated Automation System (IAS), Cryogenic Liquid, Inert Gas, Solidified Gas

Description

Cryogenic Liquid Leak Prevention System and Method {SAFETY SYSTEM AND METHOD FOR CRYOGENIC LIQUID LEAKAGE}

The present invention relates to cryogenic liquid leakage prevention systems and methods.

In general, LNG vessels are a kind of low temperature fluid carriers, which contain 90% or more of methane and store liquid cargoes having a boiling point of -162 ℃, that is, cryogenic liquids stored in cargo holds. have.

These low temperature fluid carriers have an Integrated Control System (ICS) or Integrated Automation System (IAS) to automate the vessel's engine, gas and oil control and monitoring, and Efforts are being made to eliminate the risk.

The integrated automation system can monitor and control the abnormality of various facilities in the vessel through local area network (LAN), and can accumulate information detected through various monitoring into a database to detect abnormality more precisely and sensitively. In addition, it is a high-tech system that can cope with various contingencies while sailing because it is designed to exchange information with the head office via satellite.

The heat dissipation structure of the cargo hold of the low temperature fluid carrier according to the prior art is a membrane type low temperature fluid carrier, which is composed of a hull outer wall (not shown) and an inner hull 1 (inner hull), as shown in FIG. 1. It is installed in the double hull structure.

A plurality of insulation panels 2 (Insulation Panel, IP) are mounted and attached to the hull inner wall (1) by stud bolts and resin adhesive (epoxy mastic).

Insulation panel 2 is a predetermined standard is made of reinforced polyurethane foam (Reinforced Polyurethane Foam, R-PUF) and plywood (plywood) as a cryogenic insulation.

The heat insulation panel 2 has closed the bolt hole with the foam plug 4a. Filling spaces between the insulation panels 2 are filled with a flat joint (4b) or a joint fillet made of glass fiber material.

The insulation panel 2 is provided between a relatively large area of the bottom pad 2a, a relatively small area of the top pad 2b stacked thereon, and the top pad 2b. It has a top bridge pad 2c arranged.

The primary barrier is a corrugation shaped membrane 5. It is in direct contact with the cryogenic liquid and is fixed on the plywood of the top pad 2b and the top pad 2b.

Secondary barriers are rigid triplex (6) and supple triplex (7). The rigid triplex 6 is installed on the upper surface of the lower pad 2a. The triple triplex 7 is formed by an adhesive such as epoxy glue 8 between the rigid triplex 6 and the top bridge pad 2c with respect to the upper bordered area between the insulating panels 2. It is installed later.

Thereafter, the empty space C1 existing between the primary barrier and the secondary barrier and the empty space C2 existing between the secondary barrier and the inner wall of the hull are filled with an inert gas such as nitrogen gas for preventing explosion. In addition, the pressure control based on the pre-planned setpoint is controlled and monitored in real time by the aforementioned integrated automation system.

However, the heat dissipation structure of the cargo hold of the low temperature fluid carrier according to the prior art damages the barrier due to the hull damage or the sloshing phenomenon during the operation. This can occur, in which case there is a lack of means for preventing the leakage or leakage of cryogenic liquid during storage and transport.

For example, if there is a leak in the membrane, which is the primary barrier, the cryogenic liquid leaked through it fills the empty space between the primary and secondary barriers, and there is a leak in the secondary barrier, the supplement or rigid triplex. In this case, the cryogenic liquid is also filled in the empty space between the secondary barrier and the inner wall of the hull, thereby lowering the hull strength and brittle fracture may occur.

In addition, the heat dissipation structure of the cargo hold of the low temperature fluid carrier according to the prior art, even if the leaked portion can be detected by using a leak detection means using a pressure gauge or a cargo tank leak position detection means using an acoustic sensor, the leaked portion Since it cannot be repaired immediately in a ship in operation at sea, it must arrive at a port capable of repairing the hull as soon as possible without leaving a leak, so that it is not possible to respond promptly due to the occurrence of leakage and to ensure hull safety. This is not possible.

Therefore, there is a need for a new technology that can immediately prevent a leak and prevent it from spreading.

Therefore, the present invention has been made in order to solve the problems of the prior art as described above, when detecting the leakage of cryogenic liquid due to damage to the cargo hold barrier, by forming the ice by purging the solidified gas to reduce the leakage site It is a technical challenge to provide cryogenic liquid leakage prevention systems and methods that can protect cargo and hulls quickly in response to leakage accidents.

The technical problem of the present invention as described above, as described in detail below, the empty space or secondary barrier between the primary barrier and the secondary barrier of the cargo storage for cryogenic liquid storage is performed by the integrated control system and A cryogenic liquid leakage prevention system installed in a vessel in which an inert gas line extends toward an empty space between inner walls of the hull, the cryogenic liquid leakage prevention system comprising: an electromagnetic valve switching valve coupled to the inert gas line; A solidification gas line piped to the switching valve to supply a solidification gas toward the inert gas line; Solidified gas storage means piped to the solidified gas line and the solidified gas is stored; And a leakage preventing controller connected to the switching valve and configured to perform line switching control of the switching valve in response to leakage detection of the cryogenic liquid.

In addition, the cryogenic liquid leakage prevention method provided in the present invention is an empty space between the primary barrier and the secondary barrier of the cryogenic liquid storage cargo hold is monitored by the integrated control system, and the empty space between the secondary barrier and the hull inner wall A monitoring step in which the inert gas line extends toward the vessel, monitoring the cargo hold in which cryogenic liquid is stored in association with the integrated control system; A solidification gas supply preparation step of opening the solidification gas supply valve of the solidification gas storage means when detecting the leakage of the cryogenic liquid; A valve control step of controlling the valve to communicate the inert gas line with the solidified gas line; And a purging step of the solidified gas reaching the leaked site to form ice to block the leaked site.

The cryogenic liquid leakage prevention system according to the present invention is interlocked with an integrated automation system (IAS), which is pre-installed in a low temperature fluid carrier, and provides dry ice by supplying a solidification gas instead of an inert gas in case of an accident such as cryogenic liquid leakage. Through the direct blocking of the leak through the cryogenic liquid leaks out of the cargo hold can be quickly and safely prevented.

That is, the cryogenic liquid leakage prevention system of the present invention can prevent the hull from being brittle or broken by the cryogenic liquid in advance, and has the advantage of preventing the cryogenic liquid from leaking even during ship operation.

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

2 is a block diagram of a cryogenic liquid leakage prevention system according to an embodiment of the present invention, Figure 3 is a block diagram illustrating a method of operation of the embodiment shown in Figure 2, Figure 4 is a cryogenic temperature of the present invention It is a flowchart for explaining a liquid leakage prevention method.

First, as shown in Figs. 2 and 3, the present invention is the primary barrier 50 or the secondary barrier 67 of the cargo hold for storing the cryogenic liquid 10 (for example, LNG, etc.) corresponding to the liquid cargo. The present invention relates to a system and a method installed in a ship such as a low temperature fluid carrier in order to prepare for an accidental leak.

Vessels, such as low temperature fluid carriers, have an integrated control system 130 to monitor the cargo hold.

Inert to the empty space C1 existing between the primary barrier 50 and the secondary barrier 67 of the cargo hold, and the empty space C2 existing between the secondary barrier 67 and the hull inner wall 1. Gas (eg nitrogen gas) is filled.

The inert gas does not act as an active countermeasure against leakage or leakage of the cryogenic liquid 10 due to damage to the barriers 50 and 67, which are good for explosion prevention purposes.

With this in mind, the present invention provides a solidified gas (eg, CO ₂ ) instead of blocking the supply of existing inert gas when leakage of the cryogenic liquid 10 due to damage to the barriers 50 and 67 is detected. Purging to form ice (eg dry ice) prevents the leakage (L) (see Figure 3).

The cryogenic liquid 10 is liquefied natural gas (LNG). Liquefied natural gas has colorless, odorless and tasteless characteristics, has a molecular weight of 16.04, molecular formula CH ₄ , boiling point (boiling point) -162 ℃, freezing point -183 ℃.

Inert gas is nitrogen gas for explosion protection of the cryogenic liquid (10). Nitrogen gas has colorless, odorless and tasteless characteristics, molecular weight 28.0134, molecular formula N ₂ , boiling point -196 ℃, freezing point -210 ℃, volatile 100%.

Inert gas is managed in the inert gas generator (110). An inert gas supply valve 111 is installed in the inert gas generator 110.

The solidified gas refers to a gas which is solidified or dry iced by exposure to the liquefied natural gas or approaching within the area of influence thereof when compared with the freezing point of the liquefied natural gas. For example, the solidified gas is preferably carbon dioxide gas or has a relatively high sublimation temperature or freezing point -40 ° C to -60 ° C.

Carbon dioxide gas has common names such as CARBON ACID GAS, CARBONIC ANHYDRIDE, CARBON DIOXIDE, CARBON OXIDE, CARBON DIOXIDE GAS, and is colorless. It has a tasteless, odorless, slightly acidic taste, and has a molecular weight of 44.01, a molecular formula CO ₂ , a breaking point of -79 ° C, and a freezing point of -57 ° C. The solidified gas has a property of producing ice by contacting or cryogenically cooling the cryogenic liquid 10 with low temperature solidification or dry ice.

The solidified gas is managed in the solidified gas storage means 120.

The solidified gas line 122 extends from the solidified gas storage unit 120 and is additionally connected to the inert gas lines 112 and 113. In detail, the solidified gas line 122 is newly installed between the solidified gas storage means 120 and the electromagnetically controlled switching valve V1 for the present invention.

The inert gas lines 112 and 113 are pre-installed in the ship, and have an empty space C1 between the primary barrier 50 and the secondary barrier 67 of the cargo hold, the secondary barrier 67 and the hull inner wall. It extends toward the empty space C2 between (1), which is used in the present invention.

The switching valve V1 is provided at the connection installation point of the solidified gas line 122 and the inert gas lines 112 and 113, and has a valve structure which realizes a line switching operation by line switching control.

The line switching control means supplying one of the inert gas or the solidified gas through the valve outlet side inert gas line 113 of the switching valve V1. In other words, the line switching control is such that the first inlet for the inert gas line 112 communicates with the valve outlet of the switching valve V1 and the second inlet for the solidified gas line 122 is closed to one side. Rotating or vice versa means that the second inlet is communicated with the valve outlet and the first inlet is closed by rotating the valve inner conduit to the other side.

The line switching control of the switching valve V1 is realized by the valve driving device and the leak prevention controller 140 provided in the switching valve V1. Here, the valve driving device is connected to the leak prevention controller 140, and performs the line switching operation in accordance with the line switching control signal of the leak prevention controller 140. The operation of the line switching control signal uses the method used in the general solenoid valve control method.

The solenoid valves V2 and V3 are connected to the integrated control system 130 or the leak prevention controller 140 and are installed on the inert gas line 113.

The solenoid valves V2 and V3 perform opening and closing operations in response to valve opening and closing control of the integrated control system 130 or the leak prevention controller 140, respectively.

Based on the open side of the solenoid valves V2 and V3, the solidified gas is an empty space C1 existing between the primary barrier 50 and the secondary barrier 67, or the secondary barrier 67 and the hull inner wall. It may flow into the empty space C2 existing between (1).

The solidified gas storage means 120 is piped to the start side of the solidified gas line 122 through the solidified gas supply valve 121.

Here, the solidified gas storage means 120 may be a carbon dioxide gas room 123 previously installed in the vessel. In addition, the solidified gas storage means 120 is a first solidified gas container 124 for storing CO ₂ separately installed on the deck of the ship, or a second solidified gas storage having a freezing point at -40 ℃ ~ -60 ℃ It may be any one of the solidified gas container 125.

The integrated control system 130 is coupled to the leakage analysis equipment (S1, S2) for detecting and analyzing the cryogenic liquid leakage in the cargo hold by pressure screening, acoustic screening, frequency screening or other methods.

In addition, the integrated control system 130 is systematically coupled to interlock with the leak prevention controller 140 of the present invention.

The leak prevention controller 140 plays a role of line switching control for the switching valve V1, opening and closing control for the solenoid valves V2 and V3 or the various supply valves 111 and 121, and monitoring.

To this end, the leak-proof controller 140 is provided with a system interlocking means, a control means, a monitoring means using computer hardware and software, in conjunction with the integrated control system 130, the opening and closing operation of the solenoid valve (V2, V3) or It serves to control the line switching operation of the switching valve (V1), and to monitor the supply status of the solidified gas storage means (120).

In general, the integrated control system 130, as shown in Figure 2, the empty space (C1) between the primary barrier 50 and the secondary barrier 67, and between the secondary barrier 67 and the hull inner wall (1) Nitrogen gas is supplied to the empty space C2.

If, during the monitoring of the integrated control system 130 using the leak analysis equipment (S1, S2), the leakage portion (L) is detected in the primary barrier 50 or the secondary barrier 67, the integrated control system 130 The supply of nitrogen gas is immediately stopped by the leak-proof controller 140 in conjunction with the).

At the same time, the leak prevention controller 140 opens the inert gas line 113 toward the leakage part L in response to the opening and closing operation of the solenoid valves V2 and V3, as shown in FIG. From the solidified gas line 122, the switching valve (V1), through the inert gas line 113 to control the supply of the solidified gas toward the empty space (C1) associated with the primary barrier 50.

As the solidified gas is purged, the previously supplied inert gas exits the cargo hold through the leakage portion L.

Subsequently, the solidified gas supplied and purged is exposed to the liquefied natural gas, which is a cryogenic liquid at the leaked portion L, or solidified under the influence of the liquefied natural gas, thereby preventing the leaked portion L.

Hereinafter, the cryogenic liquid leakage method of the present invention will be described with reference to FIG. 4.

Referring to FIG. 4, the present invention performs a monitoring step of monitoring a cargo hold in which cryogenic liquid is stored by interlocking a leak prevention controller with all system components or leak analysis equipment of the integrated control system (S10).

Thereafter, during the monitoring operation of the integrated control system using the leak analysis facility, leakage of cryogenic liquid may be detected in the integrated control system, and the integrated control system notifies the leak prevention controller of the leak detection status information.

In response, the leakage prevention controller performs a solidification gas supply preparation step of closing the inert gas supply valve of the inert gas generator and opening the solidification gas supply valve of the solidification gas storage means (S20).

In addition, the leakage prevention controller controls the valve to interconnect or communicate with the solidified gas line and the inert gas line so that the solidified gas is supplied to the empty space between the bulkheads in the cargo hold where the leaking part exists or between the bulkhead and the inner wall of the hull. Perform the valve control step (S30).

As a result, the solidified gas reaches the leaked portion to form ice to purge the solidified gas to block the leaked portion (S40).

In addition, the leak prevention controller further performs a purging condition monitoring step of monitoring the solidification gas purging state by monitoring the solidification gas line, the inert gas line, the switching valve, the solenoid valve, etc. during the purging step of the solidification gas (S50).

Various information and signals acquired through this purging status monitoring step are accumulated in the leak prevention controller, transferred to the integrated control system, and shared, and information exchange with the headquarters is performed through satellite, so that repair measures can be promptly prepared. .

1 is a cross-sectional view showing a heat radiation structure of the cargo hold of the low temperature fluid carrier according to the prior art.

2 is a block diagram of a cryogenic liquid leakage prevention system according to an embodiment of the present invention.

FIG. 3 is a block diagram illustrating an operating method of the embodiment shown in FIG. 2.

Figure 4 is a flow chart for explaining the cryogenic liquid leakage prevention method of the present invention.

                       Description of the main parts of the drawing

10: cryogenic liquid 110: inert gas generator

120: solidified gas storage means 130: integrated control system

140: leak prevention controller L: leakage

Claims (5)

Cryogenic temperatures installed on ships with inert gas lines extending from the empty space between the primary and secondary barriers of the cargo hold for cryogenic liquid storage to be monitored by the integrated control system, or the empty space between the secondary and hull inner walls. In the liquid leakage prevention system, An electromagnetic valve switching valve coupled to the inert gas line; A solidification gas line piped to the switching valve to supply a solidification gas toward the inert gas line; Solidified gas storage means piped to the solidified gas line and the solidified gas is stored; A leakage preventing controller connected to the switching valve and performing line switching control of the switching valve in response to detecting leakage of the cryogenic liquid; Cryogenic liquid leakage prevention system comprising a. The method of claim 1, The solidification gas, Cryogenic liquid leak prevention system, characterized in that the carbon dioxide gas or having a freezing point of -40 ℃ to -60 ℃. The method of claim 1, The solidified gas storage means, A carbon dioxide gas room already installed on the ship; A first solidified gas container for storing carbon dioxide gas separately installed on a deck of the ship; A second solidification gas container for storing a solidification gas having a freezing point at -40 ° C to -60 ° C; Cryogenic liquid leak prevention system, characterized in that any one of. Cryogenic liquids in vessels with an inert gas line extending towards the empty space between the primary and secondary barriers of the cargo hold for cryogenic liquid storage where the integrated control system is monitored. In the leak prevention method, A monitoring step of monitoring a cargo hold in which cryogenic liquid is stored in association with the integrated control system; A solidification gas supply preparation step of opening the solidification gas supply valve of the solidification gas storage means when detecting the leakage of the cryogenic liquid; A valve control step of controlling the valve to communicate the inert gas line with the solidified gas line; Purging step of the solidified gas to the solidified gas to reach the leakage site to form ice to block the leakage site; Cryogenic liquid leakage prevention method comprising a. The method of claim 4, wherein A purging situation monitoring step of monitoring a purging state of the solidified gas during the purging step of the solidified gas; Cryogenic liquid leakage prevention method further comprising.

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