KR20120125132A - Pump connecting structure of a natural gas supply system for a marine structure - Google Patents

Abstract

PURPOSE: A pump connection structure in a natural gas supply system for an offshore structure is provided to easily arrange transfer pipes and pumps so that the pumps are freely placed in a limited space in the offshore structure. CONSTITUTION: A pump connection structure in a natural gas supply system for an offshore structure comprises a transfer pipe, a pump, and a flexible hose. The transfer pipe forms a path for LNG from a LNG storage tank to a high pressure gas injection engine. The pump discharges the LNG by compressing in order that the LNG is transferred by the transfer pipe. The flexible hose is placed between the transfer pipe and the pump. The flexible hose is installed between the transfer pipe and the suction port of the pump. The transfer pipe is extended from the upper part of the pump.

Description

PUMP CONNECTING STRUCTURE OF A NATURAL GAS SUPPLY SYSTEM FOR A MARINE STRUCTURE}

The present invention relates to a pump connection structure of a natural gas supply system for supplying LNG or boil-off gas discharged from an LNG fuel tank to a high-pressure gas injection engine as a fuel. It relates to a pump connection structure of a natural gas supply system for offshore structures that may allow for deployment.

In general, it is nitrogen oxides (NOx) and sulfur oxides (SOx) that are regulated by the International Maritime Organization among the waste gas discharged from ships, and is trying to regulate the emission of carbon dioxide (CO ₂ ). Particularly, in the case of nitrogen oxide (NOx) and sulfur oxides (SOx), it was submitted through the Protocol of the Maritime Pollution Prevention Convention (MARPOL) in 1997, In May, the requirements for the fermentation were satisfied and the regulations are being implemented.

Therefore, in order to meet these regulations, various methods have been introduced to reduce NOx emissions. Among these methods, a high pressure natural gas injection engine, for example, a ME-GI engine, has been developed and used for LNG carriers. .

Such a ME-GI engine is an offshore structure such as an LNG carrier for storing and transporting LNG (Liquefied Natural Gas) in a cryogenic storage tank (in the present specification, the offshore structure is a vessel such as an LNG carrier, an LNG RV, or a commercial vessel). , And even offshore plants such as LNG FPSO and LNG FSRU.) In this case, natural gas is used as fuel. A gas supply pressure of high pressure of around 300 bara (absolute pressure) is required.

In order to apply ME-GI engines to commercial ships without LNG storage tanks, LNG fuel tanks that can accommodate LNG as fuel are installed.

The ME-GI engine will use Boil Off Gas (BOG) as a fuel if additional liquefaction equipment is installed if necessary, depending on changes in gas and fuel oil prices and the degree of regulation of emissions. Alternatively, it is possible to re-liquefy the boil-off gas to the storage tank and use heavy fuel oil (HFO) .In particular, LNG can be easily vaporized when passing through a sea area subject to specific regulations related to environmental pollution. It can be used as a next-generation environmentally friendly engine, which is nearly 50% efficient and can be used as the main engine of LNG carriers in the future.

In order to supply LNG (or evaporated gas) contained in the LNG storage tank (or LNG fuel tank) to the ME-GI engine as fuel, a natural gas, that is, a fuel gas supply system must be provided.

Examples of such fuel gas supply systems are disclosed in WO 2009/011497, WO 2009/136793, and the like.

International Patent Publication No. WO 2009/011497 discloses that vaporized LNG discharged from an LNG storage tank is vaporized in a vaporizer and then supplied to a high-pressure gas injection engine such as an ME-GI engine, and the boil-off gas discharged from the LNG storage tank is described above. A fuel gas supply system for liquefying heat exchange with LNG in a vaporizer is disclosed.

International Patent Publication No. WO 2009/136793 discloses that LNG discharged from an LNG storage tank is compressed by a high pressure pump and then evaporated in an evaporator to be supplied to a gas engine such as a ME-GI engine, and at the same time evaporated from the LNG storage tank. A fuel gas supply system is disclosed in which a gas is compressed in an evaporative gas compressor and then liquefied in a cryogenic heat exchanger, mixed with LNG supplied to a high pressure pump, and supplied to a gas engine.

Such a fuel gas supply system is essential for supplying fuel gas in a state required by the engine, that is, a temperature and pressure required by the engine.

On the other hand, the fuel gas supply system is generally provided with a transfer means such as a reciprocating pump as a means for transfer of LNG. Since the liquefaction temperature of LNG is cryogenic at about -163 ° C at ambient pressure, the pump used in the fuel gas supply system must be able to operate in cryogenic conditions. The cryogenic reciprocating pump for ships is configured to suck the liquid, that is, LNG, by the piston or plunger reciprocating in the cylinder, and discharge at the required pressure. Compared with other types of pumps, reciprocating pumps have advantages such as relatively high pressure gain, good flow rate, and no need for a separate flow control device.

However, in the case of offshore structures such as ships, unlike the land, the installation space of the pump is limited, so it is difficult to arrange, and it is easy to align the pipe on the side of supplying natural gas to the pump and the pipe on the side discharged from the pump. There is no problem.

The present invention is to solve the conventional problems as described above, the offshore structure connecting the pump and the transfer pipe of natural gas using a flexible hose to allow the free placement of the pump in the space-limited offshore structure It is to provide a pump connection structure of the natural gas supply system.

According to the present invention for achieving the above object, in the offshore structure having a LNG storage tank for accommodating LNG and a high-pressure gas injection engine for generating propulsion, LNG as fuel from the LNG storage tank to the high-pressure gas injection engine A pump connection structure for connecting a pump included in a natural gas supply system for supplying, comprising: a transfer pipe as a passage through which LNG is transferred from the LNG storage tank to the high pressure gas injection engine; A pump for compressing and discharging LNG so that LNG is transported through the transfer pipe; A flexible hose disposed between the transfer pipe and the pump; It is provided with a pump connection structure of the natural gas supply system for offshore structures comprising a.

Preferably, the flexible hose is installed between the transfer pipe extending upstream of the pump and the suction port of the pump.

Both ends of the flexible hose are integrally formed with a flange, and the flexible hose is preferably installed by fastening the flanges at both ends to the flange formed at the end of the transfer pipe and the suction port of the pump.

The flexible hose is preferably made of SUS material that can withstand the cryogenic temperature of LNG.

The outside of the flexible hose is preferably wrapped by a heat insulating material.

The pump is preferably a cryogenic reciprocating pump for ships in which a piston or a plunger reciprocates in a cylinder to suck up liquid and discharge the liquid at a required pressure.

The pump preferably includes a drive unit driven by a motor, and a discharge unit that sucks fluid and compresses and discharges the fluid to a predetermined pressure while operating by the drive unit.

According to another aspect of the present invention, as a pump connection structure of the natural gas supply system installed in the offshore structure, the connection between the pump for compressing and discharging the natural gas and the transport pipe to which the natural gas is transported by a flexible hose A pump connection structure of a natural gas supply system for offshore structures is provided.

According to the present invention, a pump connection structure of a natural gas supply system for offshore structures using a flexible hose to connect a pump and a transfer pipe of natural gas can be provided.

Accordingly, according to the present invention, it is possible to easily align the pump with the transfer pipe for supplying the natural gas to the pump by the flexible hose, thereby allowing the arrangement of the pump freely in a marine structure with limited space.

1 is a schematic configuration diagram from a high pressure pump to an engine of a fuel gas supply system for a high pressure gas injection engine according to the present invention.
2 is a view for explaining the buffer tank filling mode of the fuel gas supply system for a high-pressure gas injection engine according to the present invention.
3 is a view for explaining a direct gas supply mode of the fuel gas supply system for a high-pressure gas injection engine according to the present invention.
4 is a view for explaining a buffer tank use mode of the fuel gas supply system for a high-pressure gas injection engine according to the present invention.
5 to 8 are views for explaining a cooling apparatus according to various embodiments of the reciprocating pump of the fuel gas supply system for a high-pressure gas injection engine according to the present invention.
9 to 12 is a schematic configuration diagram from a storage tank to a high pressure pump of a fuel gas supply system for a high pressure gas injection engine according to the present invention, and illustrates a process of cooling down the system for smooth supply of LNG. .
13 is a view showing an LNG carrier having a fuel gas supply system for a high pressure gas injection engine according to the present invention.
14A and 14B are views for explaining an arrangement position of a fuel gas supply system in an LNG carrier.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the following examples can be modified in various forms, and the scope of the present invention is not limited to the following examples.

1 is a block diagram showing a fuel gas supply system of an offshore structure having a high-pressure gas injection engine, for example, a ME-GI engine according to the present invention. The fuel gas supply system for the high pressure gas injection engine of the present invention includes all kinds of offshore structures that can use liquefied natural gas as a fuel of the high pressure gas injection engine, that is, vessels such as LNG carriers, LNG RVs, container ships, general commercial ships, etc. It can be applied to offshore plants such as LNG, FPSO and LNG FSRU.

In the case of an offshore structure equipped with an LNG storage tank for storing or transporting LNG, such as an LNG carrier, the LNG in the LNG storage tank is supplied as a fuel to the high-pressure gas injection engine. In the case of offshore structures that do not have a separate LNG storage tank for storing or transporting LNG, such as container ships or commercial ships, LNG is discharged from the LNG fuel tank that stores LNG as fuel and supplied to the high-pressure gas injection engine. do. However, in the present specification, the LNG storage tank should be understood as a concept including an LNG fuel tank.

According to the fuel gas supply system of the offshore structure having the high-pressure gas injection engine according to the present invention, the LNG (or boil-off gas) discharged from the LNG storage tank (or LNG fuel tank) (not shown), the fuel supply line (L1) While being conveyed through the pump 20 is compressed to high pressure and vaporized in the carburetor 5 is supplied as fuel to the high-pressure gas injection engine 1, such as ME-GI engine. In the case of the boil-off gas may be mixed with the LNG to be liquefied and then transported to the high-pressure gas injection engine.

The upstream side of the vaporizer | carburetor 5 is provided with the pulsation damper 3 for absorbing and reducing pulsation on a liquid surface as cryogenic equipment. The pump 20 is preferably a reciprocating pump capable of pressurizing LNG by applying to cryogenic temperatures. The pump 20 is a high pressure pump capable of compressing LNG to a high pressure of about 150 to 300 bara. As used herein, the term "high pressure" means a pressure range of a fuel gas required by a gas engine such as a ME-GI engine, for example, a pressure in the range of about 150 to 300 bara.

The vaporizer | carburetor 5 is a high pressure vaporizer, and heats and vaporizes liquid LNG by heat-exchanging with a heat medium.

At initial start-up, the fuel supply line L1 may be injected with liquid nitrogen (ie, liquid nitrogen; LN2) for cooling the system, and the liquid nitrogen injected into the fuel supply line L1 is downstream of the vaporizer 5. From the liquid nitrogen discharge line (L2) can be discharged to the outside. Liquid nitrogen discharge line (L2) may be provided with a silencer (not shown).

According to the present invention, between the vaporizer 5 and the high-pressure gas injection engine 1 of the fuel supply line (L1) is provided a buffer tank (11) capable of receiving a predetermined amount of fuel gas at a high pressure. The buffer tank 11 is not insulated and may be affected by the external environment. When the external temperature of the buffer tank 11 is higher than the temperature of the fuel gas contained in the buffer tank 11, the fuel gas contained in the buffer tank 11 may be heated by heat supplied from the outside. The buffer tank 11 has a structure capable of withstanding a pressure of approximately 300 bar, and may have a structure such as a storage tank for CNG.

The buffer tank 11 is connected in parallel with the fuel supply line L1 through the filling line L3 and the use line L4. The check valve 12 is installed in the filling line L3, and the bypass valve 13 is installed in the use line L4. In the fuel supply line L1, a control valve 14 for adjusting the flow rate to control the amount of fuel corresponding to the engine condition, an on / off valve 15 as a master valve having a shut off function, and the engine condition Gas heaters 16 for adjusting the temperature of the fuel in accordance with are sequentially installed from the upstream side to the downstream side. The control valve 14 is installed downstream of the point where the filling line L3 branches in the fuel supply line L1 and upstream of the point where the use line L4 is connected. The on-off valve 15 and the gas heater 16 are installed in the downstream side of the point where the use line L4 is connected in the fuel supply line L1.

The fuel gas supply system having a buffer tank can be operated in a buffer tank filling mode, a direct gas supply mode, a buffer tank use mode, and the like, as necessary. Each mode will be described in detail with reference to FIGS. 2 to 4. 2 to 4, hatching the inside of the valve means that the valve is open, and no hatching inside the valve means that the valve is closed.

The buffer tank filling mode will be described with reference to FIG. 2. In order to fill the fuel tank 11 with fuel gas, the check valve 12 is opened, and the bypass valve 13, the control valve 14, and the open / close valve 15 are closed. When the check valve 12 is opened, the fuel gas (that is, natural gas) compressed to a high pressure of about 300 bar is supplied to the buffer tank 11 through the filling line L3. When filling of the gas fuel to the buffer tank 11 is completed, the check valve 12 is closed.

A direct gas supply mode will be described with reference to FIG. 3. When the high-pressure gas injection engine 1 is operated, when the required load does not fluctuate rapidly, the fuel gas is supplied from the vaporizer 5 through the fuel supply line L1. At this time, the check valve 12 and the bypass valve 13 are closed, and the control valve 14 and the open / close valve 15 are opened. When in the direct gas supply mode, by adjusting the opening degree of the check valve 12, the filling of the buffer tank 11 can proceed simultaneously.

A buffer tank use mode will be described with reference to FIG. 4. When the high pressure gas injection engine 1 is operated, when the required load suddenly changes, such as during initial start-up or output sudden increase, sufficient fuel is supplied to the high pressure gas injection engine 1 only by supplying fuel from the vaporizer 5. Can't supply At this time, the check valve 12 and the control valve 14 are closed, the bypass valve 13 and the opening / closing valve 15 are opened, and the fuel gas stored in the buffer tank 11 is supplied to the high pressure gas injection engine 1. do.

In this way, when the load of the high-pressure gas injection engine 1 fluctuates rapidly, the fuel gas stored in the buffer tank is used to cope with the load fluctuation. In the present specification, the term "when the load of the high pressure gas injection engine 1 fluctuates rapidly" means that the pump 20 or the carburetor in which the load required by the high pressure gas injection engine 1 is installed in the fuel supply line L1. (5) It means the case of fluctuating beyond the capacity of equipment.

According to the present invention, even if the load required by the high-pressure gas injection engine 1 fluctuates beyond the capacity of equipment such as the pump 20 or the vaporizer 5 installed in the fuel supply line L1, the buffer tank 11 It is possible to cope with a suddenly changing load. Accordingly, it is not necessary to satisfy the load maximum value of the high-pressure gas injection engine 1 in which the size and capacity of the various components change rapidly, and the size and capacity of the various components do not need to be excessively large, and to configure the fuel gas supply system. To reduce the cost.

As the fuel gas is discharged from the buffer tank 11, when the internal pressure of the buffer tank is reduced, the temperature of the discharged fuel gas may decrease. In this case, when the temperature of the fuel gas falls below the temperature required by the engine, the fuel gas may be heated by the gas heater 16 and then supplied to the engine.

5 to 8, a cooling apparatus according to various embodiments of a reciprocating pump of a fuel gas supply system for a high pressure gas injection engine according to the present invention will be described.

The reciprocating pump 20 includes a drive unit 21 driven by a motor 22 and a discharge unit 25 that operates by the drive unit 21 and sucks fluid, that is, LNG, compresses and discharges the fluid to a predetermined pressure. ). The rotational force of the motor 22 may be transmitted to the driver 21 through the pulley 23. As the crankshaft of the drive unit 21 rotates, the piston or plunger of the discharge unit 25 compresses and discharges the fluid while reciprocating in the cylinder through a connecting unit such as a connecting rod.

A flexible hose 60 may be installed between the inlet of the pump 20 and the fuel supply line L1, so that the pipe constituting the fuel supply line L1 and the inlet of the pump 20 are not aligned correctly. If not, the connection can be easily performed.

Lubricating oil is injected into the driving unit 21 to lubricate the operation of the crankshaft and the connecting rod. As the operation of the pump 20 continues, the temperature of the lubricating oil rises, so it is necessary to cool the lubricating oil.

The cryogenic reciprocating pump for ships is a pump in which a piston or a plunger reciprocates in a cylinder to inhale liquid and discharge the liquid at a required pressure. Such a reciprocating pump has characteristics such that high pressure can be obtained relatively simply, the flow rate is good, and there is no need to install another flow control device. However, the pump using the cryogenic fluid is easily vaporized due to the heat inflow at room temperature, the suction is not properly due to the generated vapor (Vapor). In addition, in the case of ships, there are limitations in terms of layout compared to onshore, so it is necessary to examine the suction and discharge areas when installing the pump.

According to another aspect of the present invention, in the suction device of the reciprocating pump for cryogenic ultra-high pressure natural gas supply device for ships, the cryogenic flexible hose 60, rather than using a pipe that does not allow a relatively margin to the suction line (60) By using, the movement is relatively free and is not restricted by the arrangement, and the suction tube of the pump can be efficiently suctioned by applying a sufficiently large size, that is, a large diameter flexible hose, to the suction line of the pump.

If a normal pipe is used to connect the fuel supply line (L1), ie the natural gas transfer pipe and the inlet of the pump, the inlet of the transfer pipe and the pump is aligned exactly in line because the pipe does not allow a margin. Should be. By the way, when the connection between the transfer pipe and the suction port of the pump by the flexible hose 60, even if a slight error occurs, this error can be offset by the flexible hose 60, the arrangement of the transfer pipe and pump This can be facilitated.

In addition, the diameter of the flexible hose needs to be large enough to facilitate suction by the pump, and is preferably equal to or larger than the diameter of the conveying pipe.

As the flexible hose 60, a product such as JEIL F-A to F-R of Jeil Industrial Co., Ltd., or a product such as DS 01 to 08 of Dae Sung Engineering Co. can be used. The flexible hose 60 needs to be made of a material capable of maintaining rigidity even if the liquefied natural gas in a cryogenic state passes inside, for example, SUS material, and can be wrapped by an insulation material if necessary.

As the flexible hose 60, a SUS material having flanges integrally formed at both ends can be used, and the flexible hose can be installed by fastening the flanges at both ends to the flange at the pipe end and the suction port of the pump, respectively.

Although the drawing shows that the flexible hose 60 is installed only between the natural gas transfer pipe upstream of the pump and the suction port of the pump, the flexible hose may be installed between the discharge port of the pump and the natural gas transfer pipe downstream of the pump, if necessary. Can be.

On the other hand, the discharge port of the pump may be connected to the pipe bent to have a Hangul dejaja or a consonant form as the impact mitigating means, and thus the vibration of the pump may not be transmitted to the discharge side pipe by the impact mitigating means.

Typical methods for transmitting power to the pump include belts, gears, and chain drives. Among these, the V-belt driving method transmits the rotating power by friction between the belt and the belt pulley (Pulley). If there is no constant tension of the belt between the pump pulley and the motor pulley, the belt slippage occurs. When the slip of the belt occurs, the efficiency of the pump is lowered, noise is generated, and the belt is damaged due to heat generated by friction.

According to another aspect of the invention, a method and structure are provided for measuring whether a pump slips using a belt.

First, the diameter (Diameter = D1: d1) between the pump connected to the belt and the pulley of the motor is compared and set based on this ratio. In addition, each proximity sensor is mounted on the rotation drive unit of the pump and the motor to compare the ratio of the rotational speed (rpm) with the diameter ratio between the pulleys. If the belt slips while the pump is running, the ratio of the rotational speed (rpm) measured by the proximity sensor will cause an error in the diameter ratio between the pulleys. You can judge.

Proximity sensor is a device for measuring the rotational speed of each pulley of the pump and motor, any sensor of any configuration can be used if the rotational speed of the pulley can be measured.

The cooling apparatus of the first embodiment shown in FIG. 5 includes a lubricating oil circulation line L5 for circulating lubricating oil into and out of the pump 20, and a radiator 31 installed in the lubricating oil circulation line L5 to cool the lubricating oil. And a lubricating oil pump 33 for circulating the lubricating oil. A plurality of valves 35, 36, and 37 may be installed in the lubricating oil circulation line L5. Lubricating oil circulation line (L5) constitutes a closed loop.

The cooling device of the second embodiment shown in FIG. 6 differs in that it uses a heat exchanger 41 instead of a radiator as compared to the cooling device of the first embodiment shown in FIG. The LNG, which is compressed and discharged from the pump 20, is partially bypassed and supplied to the heat exchanger 41 through the bypass line L6. Since the temperature of the LNG is relatively low compared to the lubricant, it is possible to cool the lubricant.

The cooling device of the third embodiment shown in FIG. 7 is different in that it uses a heat exchanger 45 instead of a radiator as compared to the cooling device of the first embodiment shown in FIG. The heat exchanger 45 may be supplied with sea water (or fresh water) or air for heat exchange with the lubricating oil.

The cooling device of the fourth embodiment shown in FIG. 8 is different from the cooling devices of the above-described first to third embodiments forming a closed loop in that the cooling device of the fourth embodiment is an open loop. The cooling apparatus of the fourth embodiment cools the drive unit 21 of the pump 20 by nitrogen supplied from the liquid nitrogen tank 51 through the nitrogen supply line L7. The supply amount of the liquid nitrogen can be adjusted by the on-off valve 52, the liquid nitrogen is preferably heated by the heater 53 is vaporized and then supplied to the pump 20.

It is supplied to the pump 20 to cool the driving unit 21 of the pump and the heated nitrogen itself is discharged to the outside of the pump 20 may be supplied to the connection portion 27 of the pump again. The amount of nitrogen supplied to the connection 27 can be controlled by the valve 55. The connection part 27 is positioned between the discharge part 25 and the drive part 21 to transmit the driving force of the drive part to the discharge part by the connecting rod 28 or the like.

The connecting portion 27 of the pump in which the connecting rod 28 or the like is disposed is cooled by continuously receiving cold heat from the discharge portion 25, and freezing may occur. However, the temperature of the connection portion 27 can be increased by supplying nitrogen heated in the drive portion 21 to the connection portion 27.

In addition, even if leakage of LNG occurs in the discharge part 25, the gas leaked by nitrogen passing through the connection part 27 is not transferred to the driving part 21, so that an explosion accident can be prevented in advance. At this time, the nitrogen gas supplied to the connecting portion 27 functions as a seal gas that isolates the discharge portion 25 and the driving portion 21 from each other.

Nitrogen discharged from the connection portion 27 may be discharged to the atmosphere as it is, or may be stored and reused in the nitrogen storage tank 57 through the nitrogen supply line (L7) if necessary.

In the high-pressure pump and high-pressure carburetor system, which is a method of supplying fuel in the most optimal way for an LNG fueled engine, a suction drum is required to smoothly supply LNG to the high-pressure pump. Low pressure pumps are needed to supply fuel. These low pressure pumps, suction drums, and high pressure pumps require a cool down prior to operation, and a line for bypassing the low pressure pump is provided for suction drums and high pressure pumps to quickly and smoothly perform this cool down operation. Ensure a good supply of liquid nitrogen (LN2) during cool down operations.

In addition, in order to perform a good cooling down operation of the low pressure pump, a pump is added to the vent valve and a storage tank to send evaporation gas to the low pressure pump discharge line. If present, the valve of the vapor return line is opened to maintain the cool down continuously. Before operation, the vent valve is opened to perform additional cool down work if necessary.

In the initial cool down, liquid nitrogen (LN2) is used.In this case, liquid nitrogen (LN2) is poured into a vent line or suction drum to cool down the low pressure pump, and after the low pressure pump cools down, a bypass valve is used. Cool down the suction drum and high pressure pump in earnest.

After the cool down is completed, the LNG is supplied to the suction drum using LNG, and when the supply is completed, the boil-off valve is opened to maintain the low pressure pump cool down state.

According to one embodiment of the present invention, optimized use between LN2 (Liquefied Nitrogen) and remote valves prior to using LNG as a fuel in the use of LNG (Liquefied Natural Gas) even in cryogenic fluids By configuring the logic, a system and method are provided for efficient and safe cool down and smooth supply of LNG.

1 is a schematic configuration diagram of a downstream side of a high pressure pump of a fuel gas supply system for a high pressure gas injection engine according to the present invention, and FIG. 9 is a high pressure pump upstream of a fuel gas supply system for a high pressure gas injection engine according to the present invention. A schematic configuration diagram of the side is shown.

10 schematically illustrates a cool down process using LN2. The LN2 from the LN2 tank 109 flows along the line indicated by the dashed line in the drawing, and various valves 111, 112, 115, 119, 120, a low pressure pump 103, a suction drum 105, and the like. Cool equipment and piping.

11 schematically illustrates a cool down operation using LNG as necessary during operation of the system after the cool down operation using the LN 2 is completed. The LNG from the LNG storage tank 101 flows along the line indicated by the dotted line in the figure, cooling various equipment and piping such as the valves 114, 115, 116, 119, the low pressure pump 103, the suction drum 105, and the like. Let's do it. Meanwhile, the liquid nitrogen accumulated in the pipe between the valve 111 and the valve 112 may be vented through the valve 113 after being vaporized. The boil-off gas may be returned to the LNG storage tank 101 through the valve 116 and the boil-off gas return line.

12 schematically illustrates a method of utilizing a low pressure pump, that is, a feed pump 103 as a booster pump. The LNG of the LNG tank 101 stored at a pressure of about 2.5 bar or less is pressurized by about 5 to 10 bar by the low pressure pump 103 and then supplied to the high pressure pump 107.

When the low pressure pump 103 is utilized as a booster pump, the suction drum 105 may not be used. The suction drum 105 is a container for smoothly supplying LNG to the high pressure pump 107, and the low pressure pump 103 may be used for supplying and filling LNG to the suction drum. The high pressure pump 107 of FIGS. 9 to 12 has the same configuration as the reciprocating pump 20 of FIG. 1, but has been given a member number separately for convenience.

When the fuel gas supply system of the present invention is applied to an LNG carrier having a plurality of LNG storage tanks, that is, four or five, the LNG used as fuel is the second to the third (tank 4) from the bow for reasons of ballast. Dogs), or from the second to fourth tanks (five tanks).

However, the longer the transport path of the LNG, the greater the amount of generated evaporated gas, and considering the efficiency of the entire system, it is preferable to discharge the LNG from the LNG storage tank located closest to the engine to use as fuel. In addition, if the LNG to be used as fuel is discharged from only one LNG storage tank, it may cause a problem that can not supply the fuel when fixing the valves, pumps, etc. of the pipe, it is possible to discharge the LNG from at least two LNG storage tanks It is desirable to configure the system for use as fuel.

For example, in the case of an LNG carrier in which four LNG storage tanks are installed, LNG is discharged from an LNG storage tank located at the third to fourth (tank 3 and 4) from the bow, and the LNG storage tank is 5 In the case of the LNG carrier is installed, it is preferable to discharge the LNG from the LNG storage tank located in the fourth to fifth (tanks 4 and 5) from the bow as shown in FIG.

Hereinafter, an embodiment in which the fuel gas supply system S of the present invention is installed in an LNG carrier having five LNG storage tanks 101 will be described with reference to FIGS. 13, 14A, and 14B.

The fuel gas supply system (FGS) S includes a high pressure pump 20 or 107 for compressing LNG discharged from the LNG storage tank 101 to a pressure required by the engine, and the high pressure pump. The high pressure vaporizer 5 which vaporizes the compressed LNG by the gas supply and supplies it to the high pressure gas injection engine 1, and various piping and valves from the LNG storage tank 101 to the engine 1, etc. are included.

In addition, as described with reference to FIGS. 1 to 4, the fuel gas supply system S of the present invention receives fuel gas from the vaporizer 5 in advance, and stores the fuel gas in advance of the high pressure gas injection engine 1. It may further include a buffer tank 11 for supplying the stored fuel gas to the high pressure gas injection engine 1 when the load increases, to follow the load variation of the high pressure gas injection engine 1.

In FIG. 13, a part of piping from the LNG storage tank 101 to the engine 1 and a fuel discharge pump 101a located inside the LNG storage tank 101 are located outside the fuel gas supply system S. In FIG. Although shown and shown as not included in the fuel gas supply system, this is for convenience of the city. In other words, the fuel gas supply system in a broad range includes all of a series of equipment for supplying LNG as fuel to the engine, and all the pipes from the fuel discharge pump 101a or the LNG storage tank 101 to the engine 1 are used. Include. However, the negotiated fuel gas supply system S may be considered not to include some of the pipes from the fuel discharge pump 101a or the LNG storage tank 101 to the engine 1, In the description made with reference to FIG. 13 to FIG. 14B, the fuel gas supply system S should be considered to mean the fuel gas supply system in the above-described discussion.

The fuel gas supply system S thus constructed is preferably disposed at a position as close to the high pressure gas injection engine 1 and the LNG storage tank 101 as possible. Since the high pressure gas injection engine 1 is located in the engine chamber 150 of the ship, the fuel gas supply system S is preferably disposed adjacent to the engine chamber 150 and the LNG storage tank 101. Since the engine chamber 150 has a high internal temperature, it may not be preferable that the fuel gas supply system S in which the cryogenic fluid flows is installed inside the engine chamber 150.

To this end, according to the present invention, the fuel gas supply system (S), as shown in Figure 14a, in the longitudinal direction of the hull, in the position closest to the engine chamber 150 disposed on the stern side and the engine chamber It may be disposed between the LNG storage tank 101 disposed.

Alternatively, as shown in FIG. 14B, the fuel gas supply system S may be disposed up and down between the engine chamber 150 and the living space 160. Since the residential space 160 is a space required for sailors to live or adjust vessels and control various equipment and systems, the residential space 160 needs to be isolated from the fuel gas supply system S in which LNG, which is explosive fluid, is transferred. In order to secure the safety of the living space 160, it is preferable that at least one of protection means such as A60 bulkhead, trunk space, etc. is installed between the fuel gas supply system S and the living space 160.

In the above description, the fuel gas supply system and method of the present invention has been described as an example applied to an offshore structure such as an LNG carrier, but the fuel gas supply system and method of the present invention is used to supply fuel to a high-pressure gas injection engine on land. Of course, it can be applied.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention will be.

1: high pressure gas injection engine 5: vaporizer
11: buffer tank 16: gas heater
20, 107: high pressure pump 21: drive part
22: motor 23: pulley
25 discharge part 60 flexible hose

Claims (8)

A pump included in a natural gas supply system for supplying LNG as a fuel from the LNG storage tank to the high pressure gas injection engine in an offshore structure having an LNG storage tank containing LNG and a high pressure gas injection engine for generating propulsion force. As a pump connection structure for connecting
A transfer pipe serving as a passage through which LNG is transferred from the LNG storage tank to the high pressure gas injection engine;
A pump for compressing and discharging LNG so that LNG is transported through the transfer pipe;
A flexible hose disposed between the transfer pipe and the pump;
Pump connection structure of the natural gas supply system for offshore structures comprising a. The method according to claim 1,
And said flexible hose is installed between said conveying pipe extending upstream of said pump and a suction inlet of said pump. The method according to claim 1,
A flange is integrally formed at both ends of the flexible hose, and the flexible hose is installed by fastening the flanges at both ends to the flange formed at the end of the transfer pipe and the suction port of the pump. Pump connection structure of natural gas supply system. The method according to claim 1,
The flexible hose is a pump connection structure of the natural gas supply system for offshore structures, characterized in that made of SUS material that can withstand the cryogenic temperature of LNG. The method according to claim 1,
The outside of the flexible hose is the pump connection structure of the natural gas supply system for offshore structures characterized in that it is wrapped by a heat insulating material. The method according to claim 1,
The pump connection structure of the natural gas supply system for offshore structures, characterized in that the piston or the plunger is a cryogenic reciprocating pump for the ship to suck the liquid by the reciprocating motion in the cylinder to discharge the required pressure. The method of claim 6,
The pump includes a drive unit driven by a motor, and the pump connection structure of the natural gas supply system for offshore structures, characterized in that it comprises a discharge unit for operating the fluid by the suction portion to compress and discharge to a predetermined pressure. As the pump connection structure of the natural gas supply system installed in the offshore structure,
A pump connection structure of a natural gas supply system for offshore structures, characterized in that it is connected by a flexible hose between the pump for compressing and discharging the natural gas and the transport pipe to which the natural gas is transported.

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