fuel supply unit

Abstract

To provide a fuel supply device capable of directly charging a boil-off gas compressed by a compressor to a main machine so as to miniaturize and dispersedly install the compressor, and to provide a liquefied natural gas fuel ship and a liquefied natural gas carrier with the fuel supply device.SOLUTION: A fuel supply device includes: a low pressure heater 2 to which a low-temperature boil-off gas of a liquefied fuel gas 1a stored in a tank 1 is sent to heat the boil-off gas to a normal temperature; a low-pressure compressor 3 for compressing the boil-off gas heated to the normal temperature to have a low pressure within 16 bar G; and a high-pressure compressor 4 as a reciprocation compressor of a plurality of stages, compressing the boil-off gas compressed to the low pressure to a pressure required by a main machine 11 and supplying the same to the main machine.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fuel supply device, a liquefied natural gas fueled ship, and a liquefied natural gas carrier, and more specifically to a fuel supply device in which boil-off gas compressed by a compressor can be directly fed into a main internal combustion engine ((propulsion engine), hereinafter referred to as the main engine) and in which the compressor can be made smaller and installed in a distributed manner, and to a liquefied natural gas fueled ship and a liquefied natural gas carrier equipped with this fuel supply device. [Background technology]

[0002] Conventionally, it has been known to use a high-flow, high-pressure boil-off gas compressor (HPC) to pressurize boil-off gas from liquefied fuel gas stored in a large-capacity tank that generates a large amount of boil-off gas, such as the tank of a liquefied fuel gas carrier, so that the boil-off gas can be injected into the main engine.

[0003] However, it is not common to compress boil-off gas from liquefied fuel gas stored in small-capacity tanks that generate a small amount of boil-off gas, such as the tanks of liquefied fuel gas fueled ships, using a simple, small-flow, high-pressure boil-off gas compressor and injecting it into the main engine.

[0004] Patent Document 1 describes a fuel supply device that compresses boil-off gas using a compressor. In this fuel supply device, boil-off gas (BOG) from a tank is compressed by the compressor and supplied to auxiliary machinery such as a power generation engine, and is also combined with liquefied fuel gas (LG) from a tank. The liquefied fuel gas combined with the compressed boil-off gas is compressed by a pump and supplied to the main engine.

[0005] Patent Document 2 describes a fuel supply device that compresses boil-off gas using a compressor. In this fuel supply device, boil-off gas from a tank is compressed by the compressor and supplied to auxiliary machinery such as a power generation engine, and is also sent to a first heat exchanger via a second heat exchanger, where it is cooled and re-liquefied by liquefied fuel gas from the tank. The re-liquefied boil-off gas is merged with the liquefied fuel gas from the tank. The liquefied fuel gas merged with the re-liquefied boil-off gas passes through the first and second heat exchangers, where the boil-off gas is cooled, and sent to the main engine.

[0006] Non-Patent Document 1 describes a fuel supply system in which boil-off gas is heated by a heater and compressed by a multi-stage compressor (MHP). In this fuel supply system, boil-off gas from a tank is heated by a preheater, compressed by the multi-stage compressor, and merged with liquefied natural gas (LNG) from a tank. The liquefied fuel gas from the tank is pressurized by a pump, vaporized in a vaporizer, merged with the compressed boil-off gas, and sent to the main engine. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6966661 [Patent Document 2] Utility Model Registration No. 3231536 [Non-patent literature]

[0008] [Non-Patent Document 1] Burkhardt MHP compressor webpage ( <https: / / www.burckhardtcompression.com / solution / gas-transport-storage / lng-fueled-merchant-ships / man-me-gi-engines / > ) Summary of the Invention [Problem to be solved by the invention]

[0009] In the fuel supply device described in Patent Document 1, the boil-off gas compressed by the compressor is merged with the liquefied fuel gas and then injected into the main engine, so the compressed boil-off gas is not directly injected into the main engine.

[0010] Also, in the fuel supply device described in Patent Document 2, the boil-off gas compressed by the compressor is re-liquefied, merged with the liquefied fuel gas, and injected into the main engine, so the compressed boil-off gas is not directly injected into the main engine.

[0011] In a configuration in which the boil-off gas compressed by the compressor is not directly fed into the main engine but is instead merged with the liquefied fuel gas, the device configuration becomes complex and large, and it is difficult to disperse the compressor and the liquefied fuel gas flow path.

[0012] In the fuel supply device described in Non-Patent Document 1, boil-off gas at normal pressure (0 barG) is supplied to the multistage high-pressure compressor. That is, the multistage high-pressure compressor must compress the boil-off gas at 0 barG to about 300 barG, which results in an increased size of the device configuration.

[0013] Therefore, an object of the present invention is to provide a fuel supply device that allows boil-off gas compressed by a compressor to be directly fed into the main engine and that enables the compressor to be made smaller and to be installed in a dispersed manner, and to provide a liquefied natural gas fueled ship and a liquefied natural gas carrier equipped with this fuel supply device.

[0014] Other objects of the present invention will become apparent from the following description. [Means for solving the problem]

[0015] The above problems are solved by the following inventions.

[0016] 1. a low-pressure heater to which low-temperature boil-off gas of the liquefied fuel gas stored in the tank is sent and which heats the boil-off gas to room temperature; a low-pressure compressor that compresses the boil-off gas heated to room temperature to a low pressure of 16 barG or less; a high-pressure compressor which is a multi-stage reciprocating compressor and compresses the boil-off gas compressed to the low pressure to the pressure required by the main engine and supplies it to the main engine; A fuel supply device comprising: 2. The boil-off gas compressed by the low-pressure compressor is also supplied to auxiliary equipment. 2. The fuel supply device according to claim 1, 3. The low-pressure compressor is a screw compressor. 2. The fuel supply device according to claim 1, 4. the tank is a fuel tank, and the liquefied fuel gas stored therein is sent to a high-pressure pump by a low-pressure pump; The high-pressure pump supplies the liquefied fuel gas to the main engine via a high-pressure heater. 4. The fuel supply device according to claim 1, 2 or 3. 5. 4. The fuel supply device according to claim 4 is installed, The liquefied fuel gas is liquefied natural gas. A liquefied natural gas fuelled ship. 6. A plurality of fuel supply devices according to item 1 are mounted in parallel, the liquefied fuel gas is liquefied natural gas; The tank is a tank for transporting liquefied natural gas. A liquefied natural gas carrier characterized by: [Effects of the Invention]

[0017] According to the present invention, a fuel supply device can be provided in which boil-off gas compressed by a compressor can be directly fed into the main engine, and the compressor can be made smaller and installed in a dispersed manner, and a liquefied natural gas fueled ship and a liquefied natural gas carrier equipped with this fuel supply device can be provided. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a block diagram showing the configuration of a fuel supply system of the present invention applied to a liquefied natural gas fueled ship. [Figure 2] FIG. 1 is a block diagram showing the configuration of a fuel supply system according to the present invention applied to a liquefied natural gas carrier. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0020] [Embodiment in which the system is installed on a liquefied natural gas fuelled ship] FIG. 1 is a block diagram showing the configuration of a fuel supply device according to the present invention.

[0021] The fuel supply device of this embodiment is an embodiment configured as a device equipped with a fuel tank 1 as a tank and mounted on a liquefied natural gas fuelled ship, as shown in Fig. 1. The fuel tank 1 contains liquefied natural gas (LNG) 1a as liquefied fuel gas.

[0022] In the fuel tank 1, the liquefied natural gas 1a naturally evaporates, generating boil-off gas (BOG) 1b. The boil-off gas 1b exists above the liquid surface of the liquefied natural gas 1a. The boil-off gas 1b in the fuel tank 1 is at normal pressure (0 barG) and has a low temperature of about -160°C.

[0023] The boil-off gas 1b in the fuel tank 1 is sent to the low-pressure heater 2 via a pipe. The low-pressure heater 2 heats the sent boil-off gas to room temperature. Room temperature is 20°C ± 15°C (JIS Z 8703). Note that the low-pressure heater 2 may heat the boil-off gas to approximately 45°C, and a cooler may be provided in the low-pressure compressor 3 (described later) or downstream thereof to reduce the temperature rise caused by compression.

[0024] The boil-off gas heated to room temperature is sent to the low-pressure compressor 3 through a pipe. The low-pressure compressor 3 compresses the sent boil-off gas to a low pressure of 16 barG or less, for example, about 6 barG. The gas compressed by the low-pressure compressor 3 has a temperature of about 45°C. The configuration of the low-pressure compressor 3 is not particularly limited, but is preferably a screw-type compressor from the viewpoints of miniaturization and low manufacturing costs.

[0025] The boil-off gas compressed by the low-pressure compressor 3 is sent through a pipe to the high-pressure compressor 4. The high-pressure compressor 4 is a multi-stage reciprocating compressor. The number of compression stages of the high-pressure compressor 4 is not particularly limited, but is preferably two to three. In this embodiment, the reciprocating compressor 4 will be described as having three compression stages. While current common technical knowledge requires five compression stages to compress the refrigerant to the required high pressure of the main engine, the high-pressure compressor according to the present invention can be realized with three or fewer compression stages due to the presence of a separate low-pressure compressor.

[0026] The three-stage reciprocating compressor 4 is configured with three cylinders 5a, 5b, and 5c connected in series, and pistons 6a, 6b, and 6c installed in the cylinders 5a, 5b, and 5c, respectively. The series connection means that the gas discharged from the cylinder 5a of the first compression stage passes through a cooler and is drawn into the cylinder 5b of the second compression stage, and the gas discharged from the cylinder 5b of the second compression stage passes through a cooler and is drawn into the cylinder 5c of the third compression stage, and the gas discharged from the cylinder 5c of the third compression stage becomes the gas discharged from the high-pressure compressor 4. If cooling of the compressed gas is not required, the cooler is not necessarily required. The three-stage reciprocating compressor is preferably a W-type reciprocating compressor, as this can suppress vibration.

[0027] The pistons 6a, 6b, 6c of each compression stage are reciprocated by drive rods 8a, 8b, 8c via engagement portions 7a, 7b, 7c with a crankshaft (not shown) by a drive source such as hydraulic pressure or an engine (not shown).

[0028] Each compression stage of the high-pressure compressor 4 compresses the intake gas to a pressure of approximately 3.5 to 4.0 times. Since the volume of gas decreases due to compression in the cylinders 5a, 5b, and 5c of each compression stage of the high-pressure compressor 4, the volume of the cylinder 5a of the second compression stage can be approximately 1 / 4.0 to 1 / 3.5 of the volume of the cylinder 5a of the first compression stage, and the volume of the cylinder 5c of the third compression stage can be approximately 1 / 4.0 to 1 / 3.5 of the volume of the cylinder 5b of the second compression stage. The high-pressure compressor 4 compresses the boil-off gas compressed by the low-pressure compressor 3 to the pressure required by the main engine, thereby converting it into a supercritical fluid. In this embodiment, the pressure required by the main engine is a high pressure of approximately 300 barG to 330 barG. The temperature of the gas compressed by the high-pressure compressor 4 is approximately 45°C. The rated discharge capacity of the high-pressure compressor 4 is, for example, approximately 250 kg / h.

[0029] In this fuel supply system, the high-pressure compressor 4 takes in and compresses gas that has been compressed to, for example, about 6 barG and heated to about 45°C. Compared to a five-stage high-pressure compressor that takes in and compresses gas at ambient pressure (0 barG) or below room temperature, the high-pressure compressor 4 has two to three compression stages, which is fewer in number. Furthermore, the cylinder diameter of each compression stage is smaller than that of a high-pressure compressor that takes in and compresses gas at ambient pressure or below room temperature. This allows for a smaller number of cylinders, thereby enabling a more compact device configuration, and a smaller cylinder diameter, thereby enabling a more compact device configuration. The compactness of the high-pressure compressor 4 allows for installation in the limited space within a ship, even on small ships.

[0030] The high-pressure compressor 4 supplies high-pressure gas or supercritical fluid to the main engine 11 via a check valve 9 and an on-off valve 10. This high-pressure gas or supercritical fluid is supplied to the main engine 11 together with gas or supercritical fluid obtained by pressurizing and / or heating liquefied natural gas 1a, which will be described later. The main engine 11 combusts the gas or supercritical fluid supplied from the high-pressure compressor 4 and the gas or supercritical fluid obtained by pressurizing and / or heating liquefied natural gas 1a, to generate mechanical power that drives a screw propeller or the like, thereby propelling the ship.

[0031] The boil-off gas compressed by the low-pressure compressor 3 is also supplied to an auxiliary device 14 via a check valve 12 and an on-off valve 13. The auxiliary device 14 is, for example, a power generation engine. The boil-off gas supplied to the auxiliary device 14 may have a different pressure from the boil-off gas sent to the high-pressure compressor 4. It is preferable to match the pressure required by the auxiliary device 14.

[0032] In this fuel supply system, the low-pressure compressor 3 and the high-pressure compressor 4 are configured as separate devices connected by piping. Therefore, the low-pressure compressor 3 and the high-pressure compressor 4 do not need to be arranged integrally. Furthermore, they do not need to be arranged in the same compartment (room), but can be arranged separately in different compartments (rooms). Therefore, compared to the need to arrange a high-pressure compressor that takes in and compresses gas at a temperature below room temperature at approximately normal pressure (0 barG), there is a greater degree of freedom in arrangement, allowing for free arrangement in the limited space within the ship. Furthermore, they can be arranged even on small ships.

[0033] Liquefied natural gas 1a stored in fuel tank 1 is sent to high-pressure hydraulic pump 16 by low-pressure pump 15. High-pressure hydraulic pump 16 is a reciprocating pump. High-pressure hydraulic pump 16 is configured with multiple cylinders 17, 17, 17 arranged in parallel (for example, two regular cylinders and one spare), and pistons 18, 18, 18 installed inside each of these cylinders 17, 17, 17. Note that the number of cylinders is not limited to the example shown in the figure, and may be any number as needed.

[0034] The pistons 18, 18, 18 housed in the cylinders 17, 17, 17 are reciprocated by drive rods 20, 20, 20 via engagement portions 19, 19, 19 with a crankshaft (not shown) by a drive source such as hydraulic pressure or an engine (not shown).

[0035] The high-pressure hydraulic pump 16 pressurizes the fuel in liquid form in each of the cylinders 17, 17, 17 to about 33 MPaG (corresponding to about 330 barG) and sends it to the high-pressure heater 21. The rated discharge capacity of the high-pressure hydraulic pump 16 is, for example, about 1800 (kg / h) to 2000 (kg / h) (density 450 kg / m 3 The high-pressure heater 21 vaporizes the fuel and supplies it to the main engine 11 via a check valve 22 and an on-off valve 23.

[0036] The main engine 11 burns the high-pressure gas that has passed through the high-pressure hydraulic pump 16 and the high-pressure heater 21 to generate mechanical power and propel the ship. When the boil-off gas 1b remains in excess even after being supplied to the auxiliary engine 14, the high-pressure discharge gas from the high-pressure compressor 4 can also be supplied to the main engine 11. The main engine 11 may be a dual-fuel engine that can also use petroleum fuel.

[0037] Furthermore, by supplying the high-pressure discharge gas from the high-pressure compressor 4 together with the high-pressure gas that has passed through the high-pressure hydraulic pump 16 and the high-pressure heater 21, the boil-off gas 1b in the fuel tank 1 can be used without waste, the amount of gas or supercritical fluid that is pressurized and / or heated from the liquefied natural gas 1a that is supplied can be reduced, and fuel efficiency can be improved. Furthermore, by adding the high-pressure gas or supercritical fluid from the high-pressure compressor 4 without reducing the amount of gas or supercritical fluid that has passed through the high-pressure hydraulic pump 16 and the high-pressure heater 21 that is supplied, the output of the main engine 11 can be increased.

[0038] [Embodiment in which the system is installed on a liquefied natural gas carrier] In the above-described embodiment, the fuel supply device of the present invention is installed on a liquefied natural gas fuelled ship, but the present invention is not limited to this, and the fuel supply device can also be installed on a liquefied natural gas carrier.

[0039] When this fuel supply device is installed on a liquefied natural gas carrier, as shown in Fig. 2, boil-off gas 1b is drawn from a liquefied natural gas transport tank 24, not from the fuel tank 1, through low-pressure heaters 2, 2, 2 and low-pressure compressors 3, 3, 3 of a plurality of fuel supply devices 4A, 4B, 4C installed in parallel, and then into high-pressure compressors 4, 4, 4. Like the fuel supply devices in the above-described embodiments, the fuel supply devices 4A, 4B, 4C are configured to include a low-pressure heater 2, a low-pressure compressor 3, and a high-pressure compressor 4.

[0040] The boil-off gas 1b generated from the liquefied natural gas transport tank 24 is larger in volume than the boil-off gas 1b generated from the fuel tank 1, so in this embodiment, multiple fuel supply devices 4A, 4B, 4C are installed in parallel, and the total rated discharge capacity of the high-pressure compressors 4, 4, 4 is made larger than in the previously described embodiment. The number of fuel supply devices 4A, 4B, 4C installed in parallel is not particularly limited, and can be installed according to the required rated discharge capacity.

[0041] The low-pressure heater 2 and the low-pressure compressor 3 may be common to each of the fuel supply devices 4A, 4B, and 4C. In other words, the fuel may be sent via one low-pressure heater 2 and one low-pressure compressor 3 to multiple high-pressure compressors 4, 4, and 4.

[0042] The main engine 11 burns the high-pressure gas or supercritical fluid from the high-pressure compressors 4, 4, 4 to generate mechanical power and propel the ship. The main engine 11 of the liquefied natural gas carrier is a dual-fuel engine that can also be powered by petroleum fuel, but by also using the high-pressure gas or supercritical fluid from the high-pressure compressors 4, 4, 4 as fuel, the boil-off gas 1b in the liquefied natural gas transport tank 24 can be used without waste, the amount of petroleum fuel supplied can be reduced, and fuel efficiency can be improved. In addition, by adding the high-pressure gas or supercritical fluid from the high-pressure compressors 4, 4, 4 without increasing the amount of petroleum fuel supplied, the output of the main engine 11 can be increased.

[0043] In this fuel supply system, similarly to the above-described embodiment, the high-pressure compressors 4, 4, 4 can be made compact, and therefore can be arranged in a limited space inside the ship.

[0044] Furthermore, in this fuel supply device, as in the previously described embodiment, the low-pressure compressors 3, 3, 3 and the high-pressure compressors 4, 4, 4 can be distributed and arranged in different compartments (rooms), which allows for great freedom in arrangement and enables free arrangement within the limited space inside the ship.

[0045] The present invention is not limited to the above-described embodiments, and various improvements and design changes may be made without departing from the spirit of the present invention. For example, the liquefied fuel gas is not limited to liquefied natural gas (LNG) as in the above-described embodiments, but may be liquefied ethane gas (LEG) or various liquefied petroleum gases (LPG).

[0046] In addition, it goes without saying that specific detailed structures, numerical values, etc., and the control contents of the control device, etc., can be changed as appropriate. In addition, the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0047] 1 fuel tank 1a Liquefied natural gas (LNG) 1b Boil-off gas (BOG) 2 Low-pressure heater 3 Low-pressure compressor 4. High-pressure compressor 4A, 4B, 4C fuel supply system 5a First compression stage cylinder 5b Second compression stage cylinder 5c Third compression stage cylinder 6a First compression stage piston 6b Second compression stage piston 6c Third compression stage piston 7a, 7b, 7c Engagement part 8a, 8b, 8c drive rods 9. Check valve 10. Opening and closing valve 11 Main engine 12 Check valve 13 Opening and closing valve 14 Auxiliary equipment 15 Low-pressure pump 16 High-pressure hydraulic pump 17 cylinders 18 Piston 19 Engagement part 20 Drive rod 21 High-pressure heater 22 Check valve 23 Opening and closing valve 24 Liquefied natural gas transport tanks

Claims

1. a low-pressure heater to which low-temperature boil-off gas of the liquefied fuel gas stored in the tank is sent and which heats the boil-off gas to room temperature; a low-pressure compressor that compresses the boil-off gas heated to room temperature to a low pressure of 16 barG or less; a high-pressure compressor which is a multi-stage reciprocating compressor and compresses the boil-off gas compressed to the low pressure to the pressure required by the main engine and supplies it to the main engine; Equipped with the tank is a fuel tank, and the liquefied fuel gas stored therein is sent to a high-pressure pump by a low-pressure pump; The fuel supply device is characterized in that the high-pressure pump supplies the liquefied fuel gas to the main engine via a high-pressure heater.

2. The boil-off gas compressed by the low-pressure compressor is also supplied to auxiliary equipment.

2. The fuel supply system according to claim 1.

3. The low-pressure compressor is a screw compressor.

2. The fuel supply system according to claim 1.

4. The fuel supply device according to claim 1 is installed, The liquefied fuel gas is liquefied natural gas. A liquefied natural gas fuelled ship.

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