JP4347037B2 - Fuel supply apparatus for gas-fired internal combustion engine such as gas turbine and LNG ship equipped with the same - Google Patents

Description

  The present invention relates to a fuel supply apparatus for a gas-fired internal combustion engine such as a gas turbine that supplies boil-off gas and LNG from an LNG storage tank to a gas turbine as fuel, and an LNG ship equipped with the same.

In order to supply natural gas as a fuel to a gas turbine, it is necessary to increase the pressure to about 30 Bar (about 3 MPa). The use of natural gas as fuel for gas turbines is widely performed in large power plants and the like. Since these are boosted by pumping LNG (liquid state), they can be easily increased in pressure. This pressurized LNG is converted into high-pressure gas by heat exchange with seawater.
On the other hand, it is necessary to safely and efficiently treat the generated boil-off gas in an LNG carrier, etc., and its usage is used as boiler fuel that requires almost no pressure increase as disclosed in Patent Document 1. In general, there are no examples of adoption in gas-fired internal combustion engines such as gas turbines.

JP 2003-227608 A (paragraphs [0010] to [0018] and FIG. 1)

By the way, since large-scale power plants and the like use seawater for LNG vaporization, facilities for seawater freezing countermeasures and the like will be enlarged.
For LNG ships that need to effectively use boil-off gas, boosting the boil-off gas at atmospheric pressure to a high pressure is more powerful than boosting LNG, which is liquid. Depending on the gas design temperature, the scale of the equipment will increase.

  In view of the above problems, an object of the present invention is to provide a fuel supply device to a gas-fired internal combustion engine such as a gas turbine that can effectively utilize boil-off gas, and an LNG ship equipped with the same.

In order to solve the above problems, the present invention employs the following means.
A fuel supply apparatus for a gas-fired internal combustion engine such as a gas turbine according to the present invention includes a BOG supply line for supplying boil-off gas generated in an LNG tank for storing LNG to the gas-fired internal combustion engine such as a gas turbine, and the BOG An LNG supply provided in the middle of a supply line, provided with a compressor that pressurizes the boil-off gas in multiple stages, and a vaporizer in the middle, and pressurizes and vaporizes LNG from the LNG tank and supplies it to the gas-fired internal combustion engine LNG, which is interposed between the compressor of the BOG supply line and the LNG tank, sprays and vaporizes LNG before entering the vaporizer, and lowers the temperature of the introduced boil-off gas The first gradual heat generator and the intermediate stage portion of the compressor are sprayed to vaporize LNG before entering the vaporizer, and the A second heat sink that introduces compressed natural gas to lower the temperature of the natural gas, and is introduced into each of the first heat sink and the second heat sink. A flow rate adjusting valve is provided to adjust the temperature of natural gas flowing out of the first and second heat sinks to be constant around a predetermined temperature by adjusting the amount of LNG. And

  The boil-off gas at approximately atmospheric pressure generated in the LNG tank is pressurized in multiple stages by the compressor while being supplied through the BOG supply line. On the other hand, LNG stored in the LNG tank at approximately atmospheric pressure is pressurized by a pump and supplied to the LNG supply line. The supplied LNG is vaporized by a vaporizer provided in the LNG supply line. In addition, you may provide the pressurization means which further pressurizes LNG as needed before the vaporizer of an LNG supply line. These pressurized natural gases are supplied as fuel to a gas-fired internal combustion engine such as a gas turbine.

While the boil-off gas is supplied to the compressor, the temperature rises due to heat input from the surrounding environment. In contrast, in the first heat sink, a part of LNG before entering the vaporizer from the LNG supply line is supplied. The supplied LNG is sprayed and lowers the temperature of the natural gas including the boil-off gas when vaporized. Thus, the natural gas whose temperature has been lowered is supplied to the compressor.
Moreover, in the 2nd slow heat device provided in the intermediate | middle stage part of the multistage compression in a compressor, suppose that a part of LNG before entering a vaporizer from an LNG supply line is supplied. When the supplied LNG is sprayed and vaporized, the temperature of the natural gas intermediate-compressed by the compressor is lowered. The natural gas whose temperature has been lowered in this way is supplied to the subsequent compression step.
As used herein, the "multistage compressor" refers to a compressor having a plurality of compression stages, that is, a plurality of compression steps, and includes a multistage compressor, a plurality of single stage compressors, and a multistage compressor. And combinations of single stage compressor (s).
The term “natural gas” used herein refers to a mixed gas of boil-off gas and vaporized LNG, and is used to distinguish from the boil-off gas and LNG. Therefore, it means that natural gas is mainly contained, and does not exclude inclusion of a small amount of other components.

According to the present invention, the LNG vaporized in the post-process is used to vaporize the LNG, reduce the temperature of the natural gas supplied to the compressor, and further reduce the temperature of the pressurized natural gas in the intermediate stage. Similarly, since it is lowered, the compression rate and compression efficiency of the compressor are improved. When the compression rate is improved in this way, the driving power of the compressor can be reduced. In addition, since the entire apparatus can be downsized due to the effect of reducing the compressor capacity and the number of compression stages, the manufacturing cost can be reduced and the operating cost can also be reduced.
In addition, by adjusting the amount of LNG supplied to the first and second heat sinks, the temperature of the natural gas coming out of each heat sink can be adjusted, so that the temperature fluctuation of the boil-off gas Compressor performance design that is not affected by
In addition, you may provide a 2nd slow heat device between each stage of a compressor as needed.

  In addition, since a part of the LNG supplied from the LNG supply line is supplied to the BOG supply line before entering the vaporizer, the LNG supplied to the vaporizer decreases. Thus, when the amount of LNG to be processed by the vaporizer decreases, the heat source load and power for processing LNG will decrease.

  A fuel supply apparatus for a gas-fired internal combustion engine such as a gas turbine according to the present invention is interposed between the compressor of the BOG supply line and the gas turbine, and the LNG before entering the vaporizer of the LNG supply line. And a third heat sink that lowers the temperature of the natural gas by introducing the natural gas from the compressor.

According to the present invention, since the amount of heat of the natural gas from the compressor is used to vaporize LNG, the heating load on the vaporizer can be reduced. Therefore, heat source processing is simple and easy. Further, since the vaporizer itself can be downsized, the manufacturing cost is reduced.
In some cases, the vaporizer itself may be unnecessary.

A fuel supply apparatus for a gas-fired internal combustion engine such as a gas turbine according to the present invention performs heat exchange between LNG carried on the LNG supply line and natural gas sent to the second heat sink. Features.

According to the present invention, heat exchange is performed between the LNG carried in the LNG supply line and the natural gas sent to the second heat sink, so that the natural gas entering the second heat sink is The temperature is lowered using the sensible heat of LNG. As described above, when the temperature of the natural gas entering the second heat sink is lowered, the temperature of the natural gas entering the compressor is lowered accordingly, so that the compression efficiency of the compressor is increased.
On the other hand, since the temperature of the LNG carried on the LNG supply line rises, the power for vaporizing the LNG can be reduced accordingly.

  An LNG ship according to the present invention includes a fuel supply device for a gas-fired internal combustion engine such as a gas turbine according to any one of claims 1 to 3.

  According to the present invention, by providing a fuel supply device for a gas-fired internal combustion engine such as a gas turbine that can effectively use the heat quantity of boil-off gas and LNG to reduce drive power and reduce the size of the structure. A gas turbine capable of effectively utilizing the transported LNG can be used as a drive source for propulsion and the like.

According to the first aspect of the present invention, the LNG vaporized in the post-process is used to vaporize the LNG and lower the temperature of the natural gas supplied to the compressor, and further pressurize in the intermediate stage. Since the temperature of natural gas is similarly lowered, the compression rate and compression efficiency of the compressor are improved. Thus, when the compression rate is improved, the number of stages of the compressor can be reduced. Further, when the compression efficiency is improved, the driving power of the compressor can be reduced. Therefore, since the entire apparatus can be reduced in size, the manufacturing cost can be reduced and the operating cost can also be reduced.
In addition, by adjusting the amount of LNG supplied to the first and second heat sinks, the temperature of the natural gas coming out of each heat sink can be adjusted, so this temperature is unified to a predetermined value. be able to. In this way, if the temperature at the compressor and the temperature at the intermediate stage are set to a constant value, it becomes possible to design the compressor performance that is not affected by fluctuations in the boil-off gas temperature, and as a result, the structure and constituent materials can be unified. The manufacturing cost can be reduced.

  According to the second aspect of the present invention, since the amount of heat of the natural gas from the compressor is used to vaporize LNG, the processing of the heat source in the vaporizer is simple and easy. Further, the manufacturing cost of the vaporizer becomes low.

  According to the invention described in claim 3, since the heat exchange is performed between the LNG conveyed in the LNG supply line and the natural gas sent to the second heat sink, the compression efficiency of the compressor is further increased. improves. Further, the power for vaporizing LNG can be reduced accordingly.

  According to the fourth aspect of the present invention, the fuel supply to the gas-fired internal combustion engine such as a gas turbine that can reduce the driving power by effectively using the heat quantity of the boil-off gas and LNG and the structure can be reduced in size. By providing the device, a gas-fired internal combustion engine such as a gas turbine that can effectively utilize the transported LNG can be used as a driving source for propulsion and the like.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a fuel supply device 1 for a gas-fired internal combustion engine such as a gas turbine according to the present embodiment. The fuel supply device 1 includes an LNG storage tank 3 for storing LNG, a BOG supply line 5 for supplying boil-off gas generated in the LNG storage tank 3 to the gas turbine 2, and pressurized LNG in the LNG storage tank 3. And an LNG supply line 7 for supplying the gas turbine to the gas turbine.

The BOG supply line 5 includes an inlet heat sink (first heat sink) 9, a low pressure stage portion 12 of a multi-stage compressor (compressor) 11, and an intercooler along the boil-off gas flow direction. A cooler 15, an intermediate heat sink (second heat sink) 17, a high pressure stage portion 13 of the multistage compressor 11, an outlet heat sink (third heat sink) 19, and a gas heater 21 are provided. It has been.
The low pressure stage portion 12 of the multistage compressor 11 and the high pressure stage portion 13 of the multistage compressor 11 are each composed of two stages.

The LNG supply line 7 is provided with a cargo pump 23 that handles LNG, a booster pump 25 that pressurizes the LNG, an intercooler 15, and a vaporizer 27 along the LNG flow direction.
The vaporizer 27 generally uses a steam heating method.

  On the upstream side of the booster pump 25 in the LNG supply line 7, a first LNG branch pipe 29 that supplies LNG to the inlet heat sink 9 is provided. The first LNG branch pipe 29 is provided with a flow rate control valve 31 at a position before entering the inlet heat sink 9. The BOG supply line 5 is provided with a temperature detector 33 at a position exiting the inlet heat sink 9. The opening degree of the flow control valve 31 is adjusted by the detection value of the temperature detector 33.

  FIG. 2 shows a longitudinal section of the inlet heat sink 9. The structure of the inlet heat sink 9 will be described with reference to FIG. The inlet slow heatr 9 includes a hollow cylindrical container 61. The container 61 is provided with a discharge port 65 at the top and an introduction port 63 at the bottom from the center of the side surface. Both the introduction port 63 and the discharge port 65 are connected to the BOG supply line 5. An LNG introduction pipe 67 is inserted at a position above the side surface of the container 61. The LNG introduction pipe 67 is connected to the first LNG branch pipe 29. A plurality of spray holes are provided in the lower part of the LNG introduction pipe 67, and the introduced LNG is sprayed.

In the space between the introduction port 63 and the LNG introduction pipe 67, an obstacle for gas-liquid contact is arranged, and the LNG sprayed and the introduced boil-off gas come into contact with each other to vaporize the LNG. Reduce the temperature of the boil-off gas.
The natural gas having the lowered temperature is introduced into the low-pressure stage portion 12 of the multistage compressor 11 through the discharge port 65 and the BOG supply line 5.
The structure of the intermediate heat sink 17 and the outlet heat sink 19 is basically the same as that of the inlet heat sink 9. These slow heat exchangers exchange heat between the introduced LNG and natural gas, and the LNG is vaporized, so that the temperature of the natural gas is lowered as compared with the time of introduction.

In the middle of the first LNG branch pipe 29, a second LNG branch pipe 35 for supplying LNG to the intermediate heat sink 17 is provided. The second LNG branch pipe 35 is provided with a flow rate adjusting valve 37 at a position before entering the intermediate heat sink 17. Further, the BOG supply line 5 is provided with a temperature detector 39 at a position where it exits the intermediate heat sink 17. The opening degree of the flow control valve 37 is adjusted by the detection value of the temperature detector 39.
In this embodiment, the temperature of the natural gas that exits from the inlet heat sink 9 and the intermediate heat sink 17 is adjusted to be constant (approximately -100 ° C.).

  The LNG supply line 7 is provided with a bypass pipe 41 that connects the front and rear of the intercooler 15. The bypass pipe 41 is provided with a flow rate adjustment valve 43. The flow rate control valve 43 adjusts the amount of LNG introduced into the intercooler 15.

The LNG supply line 7 is provided with a third branch pipe 45 which branches at a position before flowing into the vaporizer 27 and supplies LNG to the outlet slow heatr 19. A flow control valve 47 is provided in the third branch pipe 45. In the BOG supply line 5, a temperature detector 49 is provided at a position where it exits the outlet slow heatr 19. The opening degree of the flow control valve 47 is adjusted by the detection value of the temperature detector 49.
In the present embodiment, the temperature of the natural gas that exits from the outlet cooler 19 is adjusted to be constant (approximately 15 ° C.).

  All of the LNG carried in the LNG supply line 7 is completely vaporized in the outlet slow heatr 19 and joins the BOG supply line 5. The natural gas joined to the BOG supply line 5 is supplied as fuel to the gas turbine of the gas turbine combined cycle 2.

  The natural gas supplied from the BOG branch pipe 51 branched from the BOG supply line 5 at the outlet portion of the low-pressure stage portion 12 of the multistage compressor 11 is merged with the natural gas introduced from outside the system, and the gas heater 53 The temperature is raised, and the gas is combined into a double combustion boiler or a flare stack of the gas turbine combined cycle 2.

The operation of the fuel supply apparatus for the gas turbine according to the present embodiment described above will be described.
An LNG ship generates boil-off gas in an amount that can cover about half of the required power. The boil-off gas under atmospheric pressure generated in the cargo tank is sent to the inlet heat sink 9 in a state of about −140 to −160 ° C. Due to heat input in the middle of the piping, the temperature is raised to about −100 to 0 ° C. at the inlet of the inlet heat sink 9.

  The boil-off gas introduced into the inlet heat sink 9 is now introduced through the first LNG branch pipe 29 and comes into contact with the sprayed LNG. By this contact, LNG is vaporized and the boil-off gas is cooled. In the state where the temperature of the natural gas in which both of them are mixed is lowered (standard is -100 ° C. or lower), the heat exchanger 9 exits. The outlet temperature can be set to an appropriate temperature by adjusting the supply amount of LNG.

  The natural gas whose temperature has been lowered is introduced into the low-pressure stage portion 12 of the multistage compressor 11. Therefore, the compression efficiency of the low pressure stage portion 12 of the multistage compressor 11 is improved as compared with the case where the temperature is high. In the low-pressure stage portion 12 of the multistage compressor 11, two-stage compression is performed, and the pressure is increased (standard is 0.5 MPa) and the temperature is increased (in this case, about −30 ° C.).

The natural gas whose pressure has been increased and increased is exchanged with the LNG supply line 7 when it passes through the intercooler 15 and is introduced into the intermediate heat sink 17.
The natural gas introduced into the intermediate heat sink 17 is introduced through the second LNG branch pipe 35 and comes into contact with the sprayed LNG. By this contact, LNG is vaporized and natural gas is cooled. When both are mixed and the temperature is lowered as natural gas (standard is −100 ° C.), the intermediate heat sink 9 is exited.

  In this way, the natural gas having a lowered temperature is introduced into the high-pressure stage portion 13 of the multistage compressor 11. In the high-pressure stage portion 13 of the multistage compressor 11, this natural gas is compressed in two stages and pressurized (depending on the required specifications of the gas turbine, but 3.5 MPa, −20 ° C. as a guide). This pressurized natural gas is introduced into the outlet cooler 19.

On the other hand, the LNG supplied through the LNG supply line 7 is boosted (4 MPa as a guide) by the booster pump 25. The boosted LNG passes through the intercooler 15 on the way, and obtains heat from the natural gas that has exited the low pressure stage portion 12 of the multistage compressor 11.
Then, it is vaporized by the vaporizer 27 and introduced into the outlet slow heatr 19. Before entering the vaporizer 27, a part of the LNG is introduced into the outlet heat sink 19 through the third branch pipe 45.

  The LNG introduced and sprayed into the outlet heat sink 19, the natural gas vaporized by the vaporizer 27, and the natural gas from the high-pressure stage portion 13 of the multistage compressor 11 come into contact with each other, and at high pressure, as appropriate. Temperature. This natural gas is supplied to the gas turbine from the outlet slow heater 19 via the gas heater 21.

Hereinafter, the operation and effect of the present embodiment will be described.
The boil-off gas at substantially atmospheric pressure generated in the LNG tank 3 is pressurized by the multistage compressor 11 while being supplied through the BOG supply line 5. On the other hand, the LNG stored in the LNG tank 3 at substantially atmospheric pressure is pressurized by the booster pump 25 in a liquid state while being supplied through the LNG supply line, and is then vaporized by the vaporizer 27. These pressurized natural gases are supplied to the gas turbine as fuel.

According to the present embodiment, the LNG vaporized in the post-process is used to vaporize the LNG and reduce the temperature of the natural gas supplied to the low-pressure stage portion 12 of the multistage compressor 11. Since the temperature of the pressurized natural gas is similarly reduced, the compression ratio and the compression efficiency of the multistage compressor 11 are improved. When the compression ratio is improved in this way, the number of stages and the volume flow rate of the multistage compressor can be reduced. Further, when the compression efficiency is improved, the driving power of the multistage compressor can be reduced. Therefore, since the entire apparatus can be reduced in size, the manufacturing cost can be reduced and the operating cost can also be reduced.
In addition, by adjusting the amount of LNG supplied to the inlet heat sink 9 and the intermediate heat sink 17, the temperature of the natural gas coming out of each heat sink can be adjusted, so that this temperature can be unified to a predetermined value. it can. Thus, if the temperature entering the low-pressure stage portion 12 of the multistage compressor 11 and the temperature entering the high-pressure stage portion 13 of the compressor 11 are set to a constant value, the structure and constituent materials of the compressor can be unified, so that the manufacturing cost is low. Can be.
In addition, since a part of the LNG supplied from the LNG supply line is supplied to the BOG supply line 5 before entering the booster pump 25, the LNG supplied to the booster pump 25 and the vaporizer 27 is reduced. . As described above, when the amount of LNG processed by the booster pump 25 and the vaporizer 27 decreases, the power for processing LNG decreases. Further, there is a possibility that the booster pump 25 and the vaporizer 27 can be reduced in size.

Since the heat quantity of the natural gas from the multistage compressor 11 is used to vaporize LNG, the heat source in the vaporizer 27 can be reduced. Therefore, heat source processing is simple and easy. Further, the vaporizer 27 itself can be reduced in size, so that the manufacturing cost is reduced.
In some cases, the vaporizer itself may be unnecessary.

Since heat is exchanged between the LNG transported in the LNG supply line 7 and the natural gas sent to the intermediate heat sink 17, the natural gas entering the intermediate heat sink 17 uses the sensible heat of LNG. Temperature decreases. Thus, since the temperature of the natural gas which enters into the multistage compressor 11 falls correspondingly, when the temperature of the natural gas which enters the intermediate slow heat exchanger 17 falls, the compression efficiency of the multistage compressor 11 increases.
On the other hand, since the temperature of the LNG carried on the LNG supply line rises, the power for vaporizing the LNG can be reduced accordingly.

  By providing the fuel supply device 1 to the gas-fired internal combustion engine, such as a gas turbine, which can effectively use the heat quantity of the boil-off gas and LNG to reduce the driving power and reduce the structure, A gas-fired internal combustion engine such as a gas turbine that can be used effectively can be used as a drive source for propulsion and the like.

1 is a block diagram of a fuel supply device to a gas-fired internal combustion engine such as a gas turbine according to an embodiment of the present invention. It is a longitudinal cross-sectional view of the inlet heat sink concerning one Embodiment of this invention.

Explanation of symbols

1 Fuel Supply Device 2 Gas Turbine 3 LNG Storage Tank 5 BOG Supply Line 7 LNG Supply Line 9 Inlet Heater 11 Multistage Compressor 17 Intermediate Heater 19 Outlet Heater 27 Vaporizer

Claims (4)

A BOG supply line for supplying boil-off gas generated in an LNG tank for storing LNG to a gas-fired internal combustion engine such as a gas turbine;
A compressor interposed in the middle of the BOG supply line to pressurize the boil-off gas in multiple stages;
An LNG supply line provided with a vaporizer in the middle, and supplying LNG from the LNG tank under pressure to the gas-fired internal combustion engine;
First, which is interposed between the compressor of the BOG supply line and the LNG tank, lowers the temperature of the introduced boil-off gas by spraying and vaporizing LNG before entering the vaporizer. With a heat sink
LNG, which is interposed in the intermediate stage portion of the compressor, is sprayed and vaporized before entering the vaporizer, and the natural gas intermediately compressed by the compressor is introduced to lower the temperature of the natural gas. A second heat sink,
With
In each of the first and second heat sinks, the temperature of natural gas flowing out from the first and second heat sinks is adjusted by adjusting the amount of LNG introduced. A fuel supply apparatus for a gas-fired internal combustion engine, such as a gas turbine, characterized in that a flow rate adjusting valve is provided to adjust to a constant value near a predetermined temperature .   It is interposed between the compressor of the BOG supply line and the gas turbine, sprays and vaporizes LNG before entering the vaporizer of the LNG supply line, introduces natural gas from the compressor, The fuel supply device for a gas-fired internal combustion engine such as a gas turbine according to claim 1, further comprising a third heat sink that lowers the temperature of the natural gas.   The gas turbine internal combustion engine such as a gas turbine according to claim 1 or 2, wherein heat exchange is performed between the LNG conveyed in the LNG supply line and the natural gas sent to the second slow heat generator. Fuel supply device for the engine.   An LNG ship comprising the fuel supply device for a gas-fired internal combustion engine such as a gas turbine according to any one of claims 1 to 3.

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