LNG Engine Test Device and Method for Ships
Patent Information
- Application Number
- KR1020250027071
- Authority / Receiving Office
- KR · KR
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2026-09-04
Smart Images
Figure PAT00002_ABST
Abstract
Description
Technology Field
[0001] The present invention relates to a test apparatus and method for a marine LNG engine, and more specifically, to a test apparatus and method for a marine LNG engine comprising: a fuel storage unit for storing LNG fuel in a liquid state; a gas supply unit for supplying gas to the fuel storage unit; a sensing unit for detecting the state of the fuel storage unit and controlling the fuel to be discharged to the outside; a transfer unit for transferring the fuel discharged from the fuel storage unit in a liquid state; and a fuel supply unit for vaporizing the fuel transferred through the transfer unit and supplying it to the engine side, wherein the fuel is pressurized and discharged from the fuel storage unit to the engine by the internal pressure formed by the fluid supplied to the fuel storage unit, thereby allowing the LNG fuel being discharged to the pressurizing pump to be maintained in a high-pressure supercooled state without the need for a separate boosting facility, thus preventing cavitation in the pressurizing pump and pressurizing and discharging the LNG fuel to the engine, thereby enabling efficient testing of the marine engine. Background Technology
[0002] As conventional petroleum-based propulsion systems in ships utilize heavy fuel oil and diesel fuels containing large amounts of sulfur, serious problems arise regarding air pollution from sulfur oxides (SOx), nitrogen oxides (NOx), and soot, as well as marine pollution caused by oil spills. Consequently, with the tightening of international emission regulations, natural gas, which is primarily composed of methane, is attracting attention as a next-generation marine fuel and is evaluated as an excellent alternative in terms of reducing environmental pollution and economic feasibility. Compared to conventional petroleum-based fuels, natural gas, which is primarily composed of methane, [reduces] sulfur oxides (SOx). x There is almost no emission of ), and nitrogen oxides (NO x It is suitable for responding to environmental pollution by reducing emissions by more than 90% and greenhouse gases by more than 20%, and has almost equivalent fuel efficiency. In particular, natural gas is cheaper than oil, so it also satisfies economic aspects.
[0003] Meanwhile, liquefied natural gas (hereinafter LNG) maximizes transportation efficiency by being compressed to 1 / 600 of its volume in a gaseous state and stored at cryogenic temperatures (approx. -163°C), but fuel in a gaseous state is required for actual engine operation. Therefore, in order to evaluate whether a manufactured LNG engine is operating normally and to assess its performance, a test environment is essential that converts liquid LNG into a gaseous state suitable for engine requirements and supplies it.
[0004] Engine tests conducted on land prior to installation on a vessel aim to verify the combustion characteristics, output, and stability of the engine by simulating actual operating environments. To this end, a test device is required that can precisely and efficiently evaluate whether the engine is operating normally by storing LNG fuel in tanks and supplying gaseous fuel at appropriate pressure and temperature using pressurized pumps and other fuel supply devices.
[0005] A test device for a marine LNG engine requires a booster pump to supply LNG from the fuel tank in a high-pressure gaseous state required by the engine. The booster pump is a device that pressurizes the LNG leaked from the fuel tank and transferred to a high pressure before it enters the engine. However, during the process of transferring the liquid LNG stored in the fuel tank along the transfer pipe between the fuel tank and the pump, vaporization due to heat penetration or pressure loss caused by the flow rate of LNG leaking from the fuel tank may occur. Consequently, as the fuel supplied to the booster pump moves at a high speed, bubbles are generated due to cavitation, which can lead to damage to the pump.
[0006] In existing facilities, to prevent damage to the pump caused by cavitation, a separate feed pump was installed upstream of the booster pump to increase the pressure of the LNG that had dropped during the transfer process, thereby allowing the LNG to be supplied to the booster pump while maintaining a sub-cooled state. However, this method has the disadvantage of being economically unviable due to the necessity of installing bulky and expensive equipment such as feed pumps and the continuous expenditure of costs for operating multiple pumps. Accordingly, there is a demand in the industry for the development of technology that can maintain a sub-cooled state and compensate for pressure loss during the transfer of LNG from the fuel tank to the engine without installing expensive equipment such as feed pumps. The problem to be solved
[0007] The present invention has been devised to solve the above-mentioned problems,
[0008] The objective of the present invention is to provide a test device for a marine LNG engine comprising: a fuel storage unit for storing LNG fuel in a liquid state; a gas supply unit for supplying gas to the fuel storage unit; a sensing unit for detecting the state of the fuel storage unit and controlling the fuel to be discharged to the outside; a transfer unit for transferring the fuel discharged from the fuel storage unit in a liquid state; and a fuel supply unit for vaporizing the fuel transferred through the transfer unit and supplying it to the engine side, wherein the fuel is pressurized and discharged from the fuel storage unit to the engine by the internal pressure formed by the fluid supplied to the fuel storage unit, thereby enabling testing of whether the engine is operating normally.
[0009] Another objective of the present invention is to provide a test device for a marine LNG engine, wherein the gas supply unit comprises a gas tank for storing gas, a gas supply pipe fluidly connected from the outlet end of the gas tank to the front end of the fuel storage unit, and a gas volume control valve connected to the gas supply pipe for determining the flow rate of gas supplied to the fuel storage unit, and wherein the sensing unit controls the degree of opening and closing of the gas volume control valve to maintain the internal pressure of the fuel storage unit higher than a critical value, thereby enabling the internal pressure of the fuel storage unit to be maintained at a high pressure by the gas supply unit without a separate feed pump.
[0010] Another objective of the present invention is to provide a marine LNG engine test device capable of controlling the internal pressure of the fuel storage unit to be raised and maintained according to the internal conditions of the LNG engine test device, wherein the sensing unit comprises a fuel pressure sensor that measures the internal pressure of the fuel storage unit and a controller that controls the degree of opening and closing of the gas volume control valve or the flow rate control valve according to the pressure measured by the fuel pressure sensor, and wherein the controller reduces or closes the degree of opening and closing of the gas volume control valve when the internal pressure measured by the fuel pressure sensor is higher than a threshold value, and increases the degree of opening and closing of the gas volume control valve when the internal pressure measured by the fuel pressure sensor is below the threshold value.
[0011] Another objective of the present invention is to provide a test device for a ship’s LNG engine that further comprises a discharge unit formed to discharge a predetermined amount of vaporized fuel from the fuel supply unit and return it to the fuel storage unit, wherein the discharge unit comprises a discharge pipe fluidly connected from one end of the fuel supply unit to the upper part of the fuel storage unit, and a flow control valve connected to the discharge pipe to determine the flow rate of the vaporized fuel discharged from the fuel supply unit and returned to the fuel storage unit, and wherein the detection unit controls the degree of opening and closing of at least one of the gas volume control valve or the flow control valve to automatically maintain the internal pressure of the fuel storage unit at a level higher than a threshold value.
[0012] Another objective of the present invention is to provide a test device for a marine LNG engine, wherein the transfer unit comprises a transfer pipe fluidly connected from the outlet end of the fuel storage unit to the front end of the fuel supply unit, and a pressure pump disposed at a predetermined position on the transfer pipe, so that the liquid fuel transferred by the pressure pump can be pressurized to a level usable in the engine.
[0013] Another objective of the present invention is to provide a test device for a marine LNG engine that can maintain the internal pressure of the fuel storage unit at a high pressure using only the gas supply unit or the extraction unit without a separate feed pump, by ensuring that the transfer unit does not additionally include a pressurizing means other than the pressurizing pump.
[0014] Another objective of the present invention is to provide a marine LNG engine test device capable of compensating for a drop in pressure in the fuel storage unit caused by fuel leakage or heat penetration during the initial operation of the marine LNG engine test device by returning vaporized LNG fuel through an extraction pipe, wherein the controller increases the degree of opening and closing of the gas volume control valve to increase the internal pressure of the fuel storage unit when the initial pressure of the fuel storage unit is formed, and during operation after the initial pressure of the fuel storage unit is formed, if the internal pressure measured by the fuel pressure sensor is higher than a threshold value, the degree of opening and closing of the flow control valve is reduced or closed, and if the internal pressure measured by the fuel pressure sensor is lower than a threshold value, the degree of opening and closing of the flow control valve is increased to maintain the internal pressure higher than a threshold value.
[0015] Another objective of the present invention is to provide a test device for a marine LNG engine that prevents cavitation in a pressure pump by preventing the LNG fuel flowing into the pressure pump from vaporizing due to the internal pressure of the fuel storage unit in a boosted state, wherein the threshold value is the minimum pressure at which the LNG fuel can be maintained in a liquid state as the pressure of the fuel flowing into the pressure pump, and the pressure of the fuel flowing out from the fuel storage unit to the transfer unit by the controller is controlled to be higher than the threshold value.
[0016] Another objective of the present invention is to provide a marine LNG engine test device in which the gas supply unit is a nitrogen supply device, and by utilizing the nitrogen supply device installed in an existing marine LNG engine test device, there is no need to additionally install a booster facility such as a separate feed pump, thereby allowing for efficient use of space and improving economic efficiency by preventing the occurrence of costs associated with the operation of additional facilities.
[0017] Another objective of the present invention is to provide a test method for a marine LNG engine capable of increasing the internal pressure of a fuel storage unit through a gas supply unit and delivering fuel without a separate feed pump, comprising: an initial pressure formation step of increasing the internal pressure of a fuel storage unit by supplying gas from a gas tank through a gas supply pipe; a transfer step of transferring fuel that has leaked out due to the internal pressure of the fuel storage unit through a transfer pipe; a fuel supply step of vaporizing fuel pressurized by a pressure pump and supplying it to the engine side through a fuel supply pipe; and a driving pressurization step in which, when the internal pressure of the fuel storage unit is below a threshold value, a controller raises and maintains the internal pressure of the fuel storage unit above a threshold value.
[0018] Another objective of the present invention is to provide a test method for a marine LNG engine in which, when the internal pressure of the fuel storage unit measured by the fuel pressure sensor is higher than a threshold value, the controller reduces or stops the flow rate of at least one of the gas supplied from the gas tank to the fuel storage unit through the gas supply pipe and the vaporized fuel extracted in a predetermined amount from the fuel supply pipe and returned to the fuel storage unit, and when the internal pressure of the fuel storage unit measured by the fuel pressure sensor is lower than or equal to the threshold value, the controller increases the flow rate of at least one so as to maintain the internal pressure of the fuel storage unit higher than the threshold value.
[0019] However, the technical problems that the embodiments of the present invention aim to solve are not limited to the technical problems described above, and other technical problems may exist. means of solving the problem
[0020] The present invention is implemented by an embodiment having the following configuration to achieve the aforementioned objective.
[0021] According to one embodiment of the present invention, the present invention comprises a fuel storage unit for storing LNG fuel in a liquid state, a gas supply unit for supplying gas to the fuel storage unit, a sensing unit for detecting the state of the fuel storage unit and controlling the fuel to be discharged to the outside, a transfer unit for transferring the fuel discharged from the fuel storage unit in a liquid state, and a fuel supply unit for vaporizing the fuel transferred through the transfer unit and supplying it to the engine side, wherein the fuel can be pressurized and discharged from the fuel storage unit to the engine by the internal pressure formed by the fluid supplied to the fuel storage unit.
[0022] According to another embodiment of the present invention, the gas supply unit comprises a gas tank for storing gas, a gas supply pipe fluidly connected from the outlet end of the gas tank to the front end of the fuel storage unit, and a gas volume control valve connected to the gas supply pipe to determine the flow rate of gas supplied to the fuel storage unit, and the sensing unit can maintain the internal pressure of the fuel storage unit higher than a threshold value by controlling the degree of opening and closing of the gas volume control valve.
[0023] According to another embodiment of the present invention, the sensing unit includes a fuel pressure sensor that measures the internal pressure of the fuel storage unit and a controller that controls the degree of opening and closing of the gas volume control valve or the flow rate control valve according to the pressure measured by the fuel pressure sensor. The controller can control the internal pressure of the fuel storage unit to be maintained at an increased level according to the internal conditions of the LNG engine test device by reducing or closing the degree of opening and closing of the gas volume control valve when the internal pressure measured by the fuel pressure sensor is higher than a threshold value, and increasing the degree of opening and closing of the gas volume control valve when the internal pressure measured by the fuel pressure sensor is below the threshold value.
[0024] According to another embodiment of the present invention, the test device for a ship’s LNG engine further comprises a discharge unit formed to extract a predetermined amount of vaporized fuel from the fuel supply unit and return it to the fuel storage unit, wherein the discharge unit comprises a discharge pipe fluidly connected from one end of the fuel supply unit to the upper part of the fuel storage unit, and a flow control valve connected to the discharge pipe to determine the flow rate of the vaporized fuel extracted from the fuel supply unit and returned to the fuel storage unit, and wherein the detection unit can automatically maintain and control the internal pressure of the fuel storage unit at a level higher than a threshold value by controlling the degree of opening and closing of at least one of the gas volume control valve or the flow control valve.
[0025] According to another embodiment of the present invention, the transfer unit comprises a transfer pipe fluidly connected from the outlet end of the fuel storage unit to the front end of the fuel supply unit, and a pressure pump disposed at a predetermined position on the transfer pipe, so that the liquid fuel transferred by the pressure pump can be pressurized to a level usable in the engine.
[0026] According to another embodiment of the present invention, the transfer unit may not additionally include a pressurizing means other than the pressurizing pump.
[0027] According to another embodiment of the present invention, the controller increases the degree of opening and closing of the gas volume control valve to increase the internal pressure of the fuel storage unit when the initial pressure of the fuel storage unit is formed, and during operation after the initial pressure of the fuel storage unit is formed, if the internal pressure measured by the fuel pressure sensor is higher than a threshold value, it decreases or closes the degree of opening and closing of the flow control valve, and if the internal pressure measured by the fuel pressure sensor is lower than a threshold value, it increases the degree of opening and closing of the flow control valve to maintain the internal pressure higher than a threshold value.
[0028] According to another embodiment of the present invention, the threshold value may be the pressure of the fuel flowing into the pressure pump, which is the minimum pressure at which the LNG fuel can be maintained in a liquid state.
[0029] According to another embodiment of the present invention, the gas supply unit may be a nitrogen supply device.
[0030] According to another embodiment of the present invention, the method may include an initial pressure forming step of increasing internal pressure by supplying gas from a gas tank to a fuel storage unit through a gas supply pipe, a transfer step of transferring fuel leaked by the internal pressure of the fuel storage unit through a transfer pipe, a fuel supply step of vaporizing fuel pressurized by a pressure pump and supplying it to the engine side through a fuel supply pipe, and a driving pressurization step in which, when the internal pressure of the fuel storage unit is below a threshold value, a controller raises and maintains the internal pressure of the fuel storage unit above a threshold value.
[0031] According to another embodiment of the present invention, the driving pressurization step comprises, when the internal pressure of the fuel storage unit measured by the fuel pressure sensor is higher than a threshold value, a controller reducing or stopping the flow rate of at least one of the gas supplied from the gas tank to the fuel storage unit through the gas supply pipe and the vaporized fuel extracted in a predetermined amount from the fuel supply pipe and returned to the fuel storage unit, and when the internal pressure of the fuel storage unit measured by the fuel pressure sensor is lower than or equal to the threshold value, the controller increasing the flow rate of at least one.
[0032] The above-described means for solving the problem are merely exemplary and should not be interpreted as intended to limit the invention. In addition to the exemplary embodiments described above, additional embodiments may exist in the drawings and the detailed description of the invention. Effects of the invention
[0033] The present invention can achieve the following effects through the combination and usage relationship of the embodiments described above and the configuration described below.
[0034] The present invention has the effect of efficiently testing whether the engine is operating normally by maintaining the LNG fuel being transferred to the booster pump in a high-pressure supercooled state without requiring a separate booster facility such as a bulky and expensive feed pump, thereby preventing cavitation in the booster pump and pressurizing and sending the LNG fuel to the engine.
[0035] The present invention comprises a fuel storage unit for storing LNG fuel in a liquid state, a gas supply unit for supplying gas to the fuel storage unit, a sensing unit for detecting the state of the fuel storage unit and controlling the fuel to be discharged to the outside, a transfer unit for transferring the fuel discharged from the fuel storage unit in a liquid state, and a fuel supply unit for vaporizing the fuel transferred through the transfer unit and supplying it to the engine side, wherein the fuel can be pressurized and discharged from the fuel storage unit to the engine by the internal pressure formed by the fluid supplied to the fuel storage unit.
[0036] The present invention comprises a gas supply unit including a gas tank for storing gas, a gas supply pipe fluidly connected from the outlet end of the gas tank to the front end of the fuel storage unit, and a gas volume control valve connected to the gas supply pipe for determining the flow rate of gas supplied to the fuel storage unit, wherein the sensing unit controls the degree of opening and closing of the gas volume control valve to maintain the internal pressure of the fuel storage unit higher than a critical value, thereby having the effect of maintaining the internal pressure of the fuel storage unit at a high pressure by the gas supply unit without a separate feed pump.
[0037] The present invention has the effect of controlling the internal pressure of the fuel storage unit to be maintained at an increased level according to the internal conditions of the LNG engine test device by, wherein the sensing unit comprises a fuel pressure sensor that measures the internal pressure of the fuel storage unit and a controller that controls the degree of opening and closing of the gas volume control valve or the flow rate control valve according to the pressure measured by the fuel pressure sensor, and the controller reduces or closes the degree of opening and closing of the gas volume control valve when the internal pressure measured by the fuel pressure sensor is higher than a threshold value, and increases the degree of opening and closing of the gas volume control valve when the internal pressure measured by the fuel pressure sensor is below the threshold value.
[0038] The present invention provides that the test device for a ship’s LNG engine further comprises a discharge unit formed to extract a predetermined amount of vaporized fuel from the fuel supply unit and return it to the fuel storage unit, wherein the discharge unit comprises a discharge pipe fluidly connected from one end of the fuel supply unit to the upper part of the fuel storage unit, and a flow control valve connected to the discharge pipe to determine the flow rate of the vaporized fuel extracted from the fuel supply unit and returned to the fuel storage unit, and wherein the detection unit controls the degree of opening or closing of at least one of the gas volume control valve or the flow control valve, thereby having the effect of automatically maintaining and controlling the internal pressure of the fuel storage unit at a level higher than a threshold value.
[0039] The present invention has the effect that the transfer unit comprises a transfer pipe fluidly connected from the outlet end of the fuel storage unit to the front end of the fuel supply unit, and a pressure pump disposed at a predetermined position on the transfer pipe, so that the liquid fuel transferred by the pressure pump can be pressurized to a level usable in an engine.
[0040] The present invention has the effect of maintaining the internal pressure of the fuel storage unit at a high pressure using only the gas supply unit or the extraction unit without a separate feed pump, by the transfer unit not including additional pressurizing means other than the pressurizing pump.
[0041] The present invention allows the controller to increase the internal pressure of the fuel storage unit by increasing the degree of opening and closing of the gas volume control valve when the initial pressure of the fuel storage unit is formed, and during operation after the initial pressure of the fuel storage unit is formed, if the internal pressure measured by the fuel pressure sensor is higher than a threshold value, decrease or close the degree of opening and closing of the flow control valve, and if the internal pressure measured by the fuel pressure sensor is lower than a threshold value, increase the degree of opening and closing of the flow control valve to maintain the internal pressure higher than a threshold value, thereby compensating for the pressure drop of the fuel storage unit caused by fuel leakage or heat penetration after the initial pressure is formed to discharge fuel from the fuel storage unit during the initial operation of the marine LNG engine test device through the return of vaporized LNG fuel through the discharge pipe.
[0042] The present invention has the effect of preventing cavitation in the pressure pump by preventing the LNG fuel flowing into the pressure pump from vaporizing due to the internal pressure of the fuel storage unit in a boosted state, wherein the threshold value is the pressure of the fuel flowing into the pressure pump, which is the minimum pressure at which the LNG fuel can be maintained in a liquid state, and the pressure of the fuel flowing out from the fuel storage unit to the transfer unit by the controller is controlled to be higher than the threshold value.
[0043] In this invention, the gas supply unit is a nitrogen supply device, and by utilizing the nitrogen supply device installed in an existing marine LNG engine test device, there is no need to additionally install a booster facility such as a separate feed pump, thereby allowing for efficient use of space and improving economic efficiency by preventing the occurrence of costs associated with the operation of additional facilities.
[0044] The present invention comprises an initial pressure formation step of supplying gas from a gas tank to a fuel storage unit through a gas supply pipe to increase internal pressure; a transfer step of transferring fuel leaked by the internal pressure of the fuel storage unit through a transfer pipe; a fuel supply step of vaporizing fuel pressurized by a pressure pump and supplying it to the engine side through a fuel supply pipe; and a driving pressurization step in which, when the internal pressure of the fuel storage unit is below a threshold value, a controller raises and maintains the internal pressure of the fuel storage unit above a threshold value, thereby enabling the fuel to be discharged by increasing the internal pressure of the fuel storage unit through the gas supply unit without a separate feed pump.
[0045] The present invention comprises, in the driving pressurization step, when the internal pressure of the fuel storage unit measured by the fuel pressure sensor is higher than a threshold value, a controller reduces or stops the flow rate of at least one of the gas supplied from the gas tank to the fuel storage unit through the gas supply pipe and the vaporized fuel extracted in a predetermined amount from the fuel supply pipe and returned to the fuel storage unit, and when the internal pressure of the fuel storage unit measured by the fuel pressure sensor is below the threshold value, the controller increases the flow rate of at least one so as to maintain the internal pressure of the fuel storage unit higher than the threshold value.
[0046] However, the effects obtainable from the present invention are not limited to those described above, and other effects may exist. Brief explanation of the drawing
[0047] FIG. 1 is a block diagram of a test device for a ship's LNG engine according to one embodiment of the present invention. FIG. 2 is an overall conceptual diagram of a test device for a ship's LNG engine according to one embodiment of the present invention. FIG. 3 is a block diagram of a gas supply unit according to one embodiment of the present invention. FIG. 4 is a conceptual diagram of a gas supply unit according to one embodiment of the present invention. FIG. 5 is a block diagram of an extraction unit according to one embodiment of the present invention. FIG. 6 is a conceptual diagram of an extraction unit according to one embodiment of the present invention. FIG. 7 is a schematic flowchart of a test method for a ship's LNG engine according to another embodiment of the present invention. Specific details for implementing the invention
[0048] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.
[0049] Throughout the specification of this invention, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "electrically connected" or "indirectly connected" with other elements interposed between them.
[0050] Throughout the entire specification of the present invention, when a member is described as being located "on," "on the upper," "on the top," "under," "on the lower," or "on the bottom" of another member, this includes not only cases where the member is in contact with the other member, but also cases where another member exists between the two members.
[0051] Throughout the specification of the present invention, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.
[0052] Since the volume of LNG fuel in a liquid state is reduced to 1 / 600 of that in a gaseous state, natural gas is cooled to an ultra-low temperature (approximately -163°C) and stored in a liquefied state in the fuel storage unit (10). However, in the LNG engine test device, in order to cause a combustion reaction in the engine (70) and generate output, the LNG fuel must be supplied in a gaseous state, and the temperature and pressure required to generate optimal output conditions in the engine are also different from the state of the natural gas stored in the fuel storage unit (10). The shipboard LNG engine test device (1) of the present invention can convert the LNG fuel stored in the fuel storage unit (10) into a gaseous state and supply it to the engine in a gaseous state required by the engine (70) to be tested.
[0053] The purpose of the present invention is to provide a test apparatus and method for a ship's LNG engine that can efficiently test whether the engine is operating normally by maintaining the LNG fuel being transferred to the booster pump in a high-pressure supercooled state without requiring a separate booster facility such as a feed pump, which is bulky and expensive, thereby preventing cavitation in the booster pump and pressurizing and sending the LNG fuel to the engine.
[0054] The present invention will be described in detail below with reference to FIGS. 1 to 7.
[0055] Referring to FIG. 1, a test device (1) for a ship's LNG engine according to one embodiment of the present invention comprises a fuel storage unit (10) for storing LNG fuel in a liquid state, a gas supply unit (20) for supplying gas to the fuel storage unit (10), a detection unit (30) for detecting the state of the fuel storage unit (10) and controlling the fuel to be discharged to the outside, a transfer unit (40) for transferring the fuel discharged from the fuel storage unit (10) in a liquid state, and a fuel supply unit (50) for vaporizing the fuel transferred through the transfer unit (40) and supplying it to the engine side.
[0056] In addition, the present invention may further include an extraction unit (60) that extracts a predetermined amount of vaporized fuel from the fuel supply unit (50) and returns it to the fuel storage unit (10) to increase the internal pressure of the fuel storage unit (10). In this case, the internal pressure of the fuel storage unit (10) can be increased and maintained by controlling the amount of gas and / or vaporized fuel supplied by the gas supply unit (20) and / or the extraction unit (60) by the sensing unit (30).
[0058] Referring to FIG. 2, the fuel storage unit (10) stores LNG fuel in a liquid state and can be understood as a pressure tank formed to withstand high pressure. In this case, since the fuel storage unit must withstand a higher pressure than a pressure tank that includes a feed pump in a shipboard LNG test facility that includes a conventional pump, it may have a thick inner wall thickness or be made of a material such as nickel steel, high-manganese steel, stainless steel, or aluminum alloy that has high strength and rigidity.
[0059] Specifically, unlike conventional marine LNG engine test devices, the fuel storage unit (10) can pressurize and send fuel to the pressure pump (42) described later in a subcooled state without vaporization using only the internal pressure of the fuel storage unit (10) without being equipped with a feed pump. Accordingly, the fuel storage unit (10) can be formed to have an allowable pressure higher than the allowable pressure (about 10 bar) of the fuel tank in conventional marine LNG engine test devices, and preferably can be formed to have an allowable pressure of 17 bar or more.
[0060] Additionally, the upper part of the fuel storage unit (10) is connected to receive fluid from the gas supply unit (20) and / or extraction unit (60) to be described later, and the lower part has an outlet formed to allow liquid fuel to be discharged to the transfer unit (40), so that the fuel discharged through the outlet can be pressurized and discharged to the engine (70) by the internal pressure formed by the fluid supplied to the upper part of the fuel storage unit (10).
[0061] Referring to FIGS. 2 and 3, the gas supply unit (20) can be understood as being configured to supply gas for forming an initial pressure that increases the internal pressure of the fuel storage unit (10) to cause fuel to flow out. The gas supply unit (20) may include a gas tank (21), a gas supply pipe (22), and a gas volume control valve (23).
[0062] The above gas tank (21) is a tank in which gas to be supplied to the fuel storage unit (10) is stored, and the gas is preferably an inert gas that does not react with LNG fuel, and more preferably may be nitrogen gas.
[0063] The above gas supply pipe (22) can be understood as a conduit connected so that one end is fluidly connected from the outlet end of the gas tank (21) to the front end of the fuel storage unit (10), and is configured to supply gas drawn from the gas tank (21) to the fuel storage unit (10).
[0064] The above gas volume control valve (23) may be formed between the gas tank (21) and the fuel storage unit (10) to control the flow rate of gas supplied to the fuel storage unit (10), and may also be provided on the gas supply pipe (22). By controlling the degree of opening and closing of the gas volume control valve (23) by a controller (31) to be described later, the flow rate of gas supplied from the gas tank (21) to the fuel storage unit (10) is controlled, and accordingly, the internal pressure of the fuel storage unit (10) can be controlled, and the gas supply unit (20) may be a nitrogen supply device that purges the pipeline of the facility.
[0065] The above sensing unit (30) can be understood as being configured to control the shipboard LNG engine test device (1) of the present invention according to the internal pressure of the fuel storage unit (10) measured by the fuel pressure sensor (32) or the state of the device detected by various sensors, thereby increasing and maintaining the internal pressure of the fuel storage unit (10).
[0066] The above-mentioned sensing unit (30) can be understood as a configuration that controls the shipboard LNG engine test device (1) of the present invention according to various states of the device, such as pressure, temperature, and level, detected by various sensors. The above-mentioned sensing unit (30) may include a controller (31) that controls the internal pressure of the fuel storage unit (10), a fuel pressure sensor (32) that measures the internal pressure of the fuel storage unit (10), a fuel temperature sensor (33) that measures the internal temperature of the fuel storage unit (10), a fuel level sensor (34) that measures the fuel level of the fuel storage unit (10), a transfer pressure sensor (35) that measures the pressure of the fuel flowing inside the transfer pipe (41) to be described later, and a transfer temperature sensor (36) that measures the fuel temperature inside the transfer pipe (41).
[0067] The above controller (31) can be understood as being configured to control the internal pressure of the fuel storage unit (10) by controlling the shipboard LNG engine test device (1) of the present invention according to the internal pressure of the fuel storage unit (10) measured by the fuel pressure sensor (32) or the value measured by various sensors. Specifically, the controller (30) controls various valves to maintain the internal pressure of the fuel storage unit (10) higher than a threshold value according to the internal pressure measured by the fuel pressure sensor (32) of the fuel storage unit (10), thereby allowing the pressure of the fuel flowing out from the fuel storage unit (10) to the transfer unit (40) to be controlled to be higher than a threshold value.
[0068] The above threshold value refers to a minimum pressure level that can maintain the LNG fuel flowing into the booster pump (42) described later in a liquid state, and this may correspond to or be higher than the pressure of the fuel just before it flows into the booster pump after the transferred fuel is pressurized by the feed pump provided on the front side of the booster pump in the existing ship LNG engine test facility.
[0069] The fuel pressure sensor (32) is configured to measure the internal pressure of the fuel storage unit (10), and it is preferable that it be installed on the upper part of the fuel storage unit (10) to measure the internal pressure of the fuel storage unit (10) formed by fuel in a liquid state and fluids in a gaseous state. The fuel temperature sensor (33) is configured to measure the internal temperature of the fuel storage unit (10). The fuel level sensor (34) is configured to measure the level of fuel inside the fuel storage unit (10), and it is preferable that it be installed on the upper part of the fuel storage unit (10), similar to the fuel pressure sensor (32).
[0070] The above transfer pressure sensor (35) and transfer temperature sensor (36) are configured to measure the pressure and temperature of the liquid LNG fuel flowing inside the transfer pipe (41). It is preferable that they be positioned at the front end of the pressure pump (42) as the rear end of the transfer pipe (41) to measure the pressure and temperature of the fuel flowing into the pressure pump (42) in order to prevent cavitation in the pressure pump (42) described later. Meanwhile, the sensors (32, 33, 34, 35, 36) may be transmitters and may be configured to convert the measured pressure, temperature, or level value into a signal and transmit it to the controller (31).
[0071] Referring to FIG. 4, the controller (31) can maintain the internal pressure of the fuel storage unit (10) above a threshold value by controlling the gas volume control valve (23) of the gas supply unit (20). Specifically, when the internal pressure of the fuel storage unit (10) measured by the fuel pressure sensor (32) is higher than the threshold value, the degree of opening or closing of the gas volume control valve (23) can be reduced or closed to reduce or stop the amount of gas supplied by the gas supply pipe (22). In addition, when the internal pressure measured by the fuel pressure sensor (32) is below the threshold value, the internal pressure of the fuel storage unit (10) can be maintained at an increased level by opening the gas volume control valve (23) to increase the amount of gas supplied by the gas supply pipe (22).
[0072] The above transfer unit (40) can be understood as a configuration for transferring fuel pressurized and discharged from the fuel storage unit (10). The transfer unit (40) may include a transfer pipe (41) for transferring fuel discharged from the fuel storage unit (10) to the fuel supply unit (50), a pressure pump (42) and a pressure valve (43) that are directly connected to the fuel storage unit (10) through the transfer pipe (41) and pressurize the fuel before supplying the transferred fuel to the carburetor (51) to be described later.
[0073] The above transfer pipe (41) is a pipe that is fluidly connected from the outlet end of the fuel storage unit (10) to the front end of the fuel supply unit (50), and can be understood as a conduit for transferring fuel to the pressure pump (42). At this time, the transfer pipe (41) may additionally be equipped with a supercooling maintenance device to maintain the fuel transferred to the pressure pump (42) as a supercooled liquid. Specifically, a supercooled liquid means a state in which the temperature of the LNG fuel being transferred is lower than the critical temperature and the pressure is higher than the critical pressure. At this time, the supercooling maintenance device may be a heat exchanger such as a supercooling maintenance cooling loop connected to the transfer pipe (41) to enable heat exchange and capable of maintaining a supercooled state by the circulation of a refrigerant, or a vacuum insulation plate or composite insulation material provided to surround the outer surface of the transfer pipe to prevent heat penetration from the outside.
[0074] The above-mentioned pressure pump (42) is configured to be positioned at a predetermined location on the transfer pipe (41) between the fuel storage unit (10) and the vaporizer (51) to be described later, and can be understood as a configuration that pressurizes the transferred LNG fuel to a high pressure level capable of supplying it to the engine (70), and may be a commonly used booster pump. Cavitation in the pressure pump (42) can be prevented by allowing the liquid in a supercooled state, which is pressurized and discharged by the internal pressure of the fuel storage unit (10), to flow into the pressure pump (42). The fuel flowing out through the pressure pump (42) can be pressurized to a high pressure of about 300 bar to 350 bar and flow into the vaporizer (51) to be described later.
[0075] At this time, the transfer unit (40) may not additionally include a pressurizing means other than the pressurizing pump (42). For example, the shipboard LNG engine test device (1) of the present invention can maintain the pressure of the fuel flowing into the pressurizing pump (42) at a high pressure of 10 bar or more using only the internal pressure of the fuel storage unit (10), so that a separate feed pump to prevent cavitation may not be provided upstream of the pressurizing pump (42).
[0076] Meanwhile, the above-mentioned pressure pump (42) may further include a gas remover connected to the above-mentioned transfer pipe (41) in a state capable of collecting gas in order to more effectively prevent cavitation. Specifically, the gas remover may be a gas filter including a mesh-structured filter or a bubble collector capable of collecting bubbles by means of a collection chamber.
[0077] The pressure valve (43) is configured to be installed at the rear end of the transfer pipe (41) to supply high-pressure fuel, which is pressurized and discharged from the pressure pump (42), to the vaporizer (51) described later at an appropriate level.
[0078] The fuel supply unit (50) can be understood as being configured to vaporize fuel, which has been pressurized to a high pressure by the pressure pump (42), into a gaseous state usable by the engine and supply it to the engine. The fuel supply unit (50) may include a vaporizer (51) that vaporizes liquid fuel in a supercooled state, a fuel supply pipe (52) that supplies the vaporized fuel, a pressure valve (53), and a buffer tank (54).
[0079] The above vaporizer (51) is configured to change the phase of the subcooled liquid LNG fuel, which is introduced through the transfer pipe (41) and the pressure pump (42), into natural gas in a gaseous state. Specifically, it can vaporize the liquid fuel supplied by heat transfer from an external heat source such as air, water, or a heater, and can supply the vaporized fuel to the engine (70) at an appropriate pressure and speed.
[0080] The fuel supply pipe (52) is configured to be connected to one end of the vaporizer (51) to supply vaporized fuel to the engine (70). At this time, the fuel supply pipe (52) may additionally be provided with a heat exchanger connected to the transfer pipe (41) described above to enable heat exchange, or with an insulating material that surrounds the outer surface of the transfer pipe to prevent heat penetration from the outside.
[0081] The pressure valve (53) is configured to be installed on the fuel supply pipe (52) to supply high-pressure vaporized fuel discharged from the vaporizer (51) to the buffer tank (54) described later at an appropriate level.
[0082] The buffer tank (54) is an intermediate storage tank that temporarily stores the vaporized fuel transferred through the fuel supply pipe (52) before supplying it to the engine (70). Specifically, the buffer tank (54) can improve the stable fuel supply to the engine (70) and the safety of the LNG engine test device by controlling the flow rate of the vaporized fuel, which is in a low-temperature, high-pressure state of 300 bar or more, and supplying it uniformly.
[0083] Referring to FIG. 5 and FIG. 2, the extraction unit (60) can be understood as being configured to extract a predetermined amount of vaporized fuel from the fuel supply pipe (52) and return it to the fuel storage unit (10).
[0084] During the testing process of an engine using a marine LNG engine test device, vaporization caused by heat penetration through the piping or a pressure drop inside the fuel tank due to continuous fuel leakage from the fuel storage unit may occur, which may result in damage to the test equipment or failure to supply fuel to the engine, thereby preventing the test from being conducted properly.
[0085] Accordingly, the present invention allows for the internal pressure of the fuel storage unit (10) to be compensated by extracting a predetermined amount of vaporized fuel from the fuel supply pipe (52) through the extraction unit (60) and returning it to the fuel storage unit (10).
[0086] The above extraction unit (60) may include an extraction pipe (61) that extracts vaporized fuel and returns it to the fuel storage unit (10), and a flow control valve (62) that controls the flow rate of the fuel returned to the fuel storage unit (10) through the extraction pipe.
[0087] The above-mentioned extraction pipe (61) is configured to be connected to allow the vaporized fuel to be returned from the fuel supply pipe (62) to the fuel storage unit (10). Referring to FIG. 6, one end of the extraction pipe (61) is connected to be fluidly connected from a predetermined position on the fuel supply pipe (52) to the upper part of the fuel storage unit (10). At this time, the diameter of the extraction pipe (61) is formed to be smaller than the diameter of the fuel supply pipe (52), so that the vaporized fuel can be returned to the fuel storage unit (10) without obstructing the flow rate of fuel supplied to the engine (70) through the fuel supply pipe (52).
[0088] Meanwhile, the above-mentioned discharge pipe (61) may be configured with a dual path. By configuring an auxiliary discharge pipe with a dual path separately from the above-mentioned discharge pipe (61), when the internal pressure of the fuel storage unit (10) drops rapidly, the controller (31) controls the valve of the auxiliary discharge pipe to open as well, thereby allowing the pressure to be quickly compensated through the additional return of vaporized fuel.
[0089] The above flow control valve (62) may be positioned at a predetermined location on the discharge pipe (61) between the fuel supply unit (50) and the fuel storage unit (10) to control the flow rate of vaporized fuel returned to the fuel storage unit (10). Additionally, by controlling the degree of opening and closing of the flow control valve (23) by the controller (31), the flow rate of vaporized fuel returned to the fuel storage unit (10) through the discharge pipe (61) is controlled, and accordingly, the internal pressure of the fuel storage unit (10) can be controlled. At this time, the controller (31) can determine the degree of opening and closing of the flow control valve (62) according to a predetermined algorithm based on the pressure value measured by the fuel pressure sensor (32).
[0090] Specifically, the controller (31) can control the pressure inside the fuel storage unit (10) to be increased by the gas supply from the gas supply unit (20) when the initial pressure of the fuel storage unit (10) is formed for fuel delivery according to the operation of the LNG engine test device for a ship of the present invention.
[0091] Meanwhile, in the case where the LNG engine test device (1) for a ship according to one embodiment of the present invention is configured to form pressure inside the fuel storage unit (10) only by the gas supply unit (20) and does not include the extraction unit (60), the controller (31) can control the gas volume control valve (23) of the gas supply unit (20) to open.
[0092] In contrast, when the LNG engine test device (1) for a ship according to another embodiment of the present invention is configured to form pressure inside the fuel storage unit (10) by both the gas supply unit (20) and the extraction unit (60), when forming the initial pressure inside the fuel storage unit (10), the controller (31) can form the initial pressure inside the fuel storage unit (10) by controlling only the gas volume control valve (23) of the gas supply unit (20) to open and the flow rate control valve (62) of the extraction unit (60) to close.
[0094] Referring to FIGS. 4 and 6, after an initial pressure is formed inside the fuel storage unit (10) and fuel is pressurized and discharged from the fuel storage unit, if the controller (31) determines that it is necessary to control the internal pressure of the fuel storage unit (10) during operation, the internal pressure of the fuel storage unit (10) can be controlled by at least one of the gas supply unit (20) and the extraction unit (60).
[0095] For example, in a ship LNG engine test device (1) according to one embodiment of the present invention, only the gas supply unit (20) is provided and the extraction unit (60) is not included, or there may be cases where pressurization is performed during the operation of the fuel storage unit (10) using only the gas supply unit (20) because instantaneous rapid pressurization is required. At this time, if the internal pressure of the fuel storage unit (10) decreases below a critical value after the initial pressure of the fuel storage unit (10) is formed, the controller (31) may further open the gas volume control valve (23) of the gas supply unit (20) to increase the gas supply amount. If the ship LNG engine test device (10) is provided with an extraction unit (60), the controller (31) may close the flow control valve (62) of the extraction unit (60) simultaneously with opening the gas volume control valve (23) to temporarily stop the return of vaporized fuel, thereby rapidly increasing the internal pressure.
[0096] In addition, when the LNG engine test device (1) for a ship according to one embodiment of the present invention performs pressurization during the operation of the fuel storage unit (10) solely by the extraction unit (60), the controller (31) can increase the internal pressure of the fuel storage unit (10) by closing the gas volume control valve (23) of the gas supply unit (20) and opening the flow rate control valve (62) of the extraction unit (60) to return the vaporized fuel to the fuel storage unit (10). This provides a gas saving effect by utilizing existing vaporized fuel without using additional gas, and has the advantage of enabling economical operation.
[0098] In addition, when the pressurization of the fuel storage unit (10) during operation of the ship LNG engine test device (1) according to one embodiment of the present invention is configured to be performed by both the gas supply unit (20) and the extraction unit (60), the sensing unit (30) of the present invention can control the internal pressure of the fuel storage unit (10) by performing a different function as follows.
[0099] First, when the controller (31) determines that the internal pressure of the fuel storage unit (10) is maintained at a relatively constant level and that the pressure increase of the fuel storage unit (10) is not urgent, the vaporized fuel from the extraction unit (60) can be used as the primary means of increasing the pressure during the process of increasing the internal pressure of the fuel storage unit (10), and the gas supply amount from the gas supply unit (20) can be used as an auxiliary means of increasing the pressure. In this case, the controller (31) can reduce the gas supply amount by decreasing the degree of opening and closing of the gas volume control valve (23), and can more efficiently control the internal pressure of the fuel storage unit (10) by opening the flow rate control valve (62) to increase the flow rate of the vaporized fuel returned to the fuel storage unit (10). This has the advantage of enabling a smooth and stable pressure increase while reducing gas usage by maximizing fuel recycling.
[0100] Additionally, when a sudden decrease in internal pressure of the fuel storage unit (10) occurs during normal operation of the ship's LNG engine test device (1), and the controller (31) determines that there is an urgent situation to increase the pressure of the fuel storage unit (10), gas supply can be used as a primary means rather than vaporized fuel to increase the internal pressure of the fuel storage unit (10). In this case, the controller (31) controls the degree of opening and closing of the flow control valve (62) of the extraction unit (60) to be slightly open to limit the amount of returned vaporized fuel, while opening the degree of opening and closing of the gas volume control valve (23) somewhat more widely to adjust the proportion of the gas supply amount to be greater than the amount of returned vaporized fuel, thereby allowing the internal pressure of the fuel storage unit (10) to be gradually increased. This has the advantage of preventing excessive gas usage while raising the pressure relatively quickly.
[0101] Meanwhile, the controller (31) may make a judgment based on the internal pressure of the fuel storage unit (10) measured by the fuel pressure sensor (32) using a predetermined algorithm. Specifically, the controller (31) may be configured to model the dynamic characteristics of the fuel storage unit (10) during a repeated test of a marine LNG engine through a data processing module that processes data collected in real time from various sensors including the fuel pressure sensor (32), predict the internal pressure change over a certain period of time based on the measured internal pressure of the fuel storage unit (10), and issue a command to open or close a valve in advance to ensure optimal fuel efficiency and prevent cavitation based on the prediction result.
[0103] Referring to FIG. 7, a test method (S) for a ship’s LNG engine according to another embodiment of the present invention may include an initial pressure forming step (S1) for forming an initial pressure inside a fuel storage unit (10), a transfer step (S2) for transferring fuel pressurized and sent from the fuel storage unit (10), a fuel supply step (S3) for vaporizing the transferred fuel and supplying it to the engine side, and a driving pressurization step (S4) for returning the vaporized fuel to the fuel storage unit (10) side to compensate for the reduced pressure of the fuel storage unit (10).
[0104] The above initial pressure formation step (S1) can be understood as a step of forming an initial pressure by increasing the internal pressure by supplying gas to the fuel storage unit (10) through a gas supply pipe (22) connected to supply gas from a gas tank (20) that stores gas to the fuel storage unit (10).
[0105] The above transfer step (S2) can be understood as a step of transferring fuel pressurized and discharged from the fuel storage unit (10) to the fuel supply unit (50) through a transfer pipe (41) that directly connects the fuel storage unit (10), the pressure pump (42), and the fuel supply unit (50).
[0106] The above fuel supply step (S3) can be understood as a step of vaporizing the fuel in a supercooled liquid state, which has been pressurized by the above pressure pump (42), through the vaporizer (51) and supplying it to the engine (70) side through the fuel supply pipe (52).
[0107] The above driving pressurization step (S4) can be understood as a step of compensating for a pressure drop in the fuel storage unit (10) caused by fuel leakage or heat penetration from the fuel storage unit (10) during driving after the initial pressure formation step (S1) by returning the vaporized LNG fuel through the extraction unit (60), and in which, when the internal pressure of the fuel storage unit (10) is below a threshold value, the controller (31) raises and maintains the internal pressure of the fuel storage unit (10) above the threshold value.
[0108] Specifically, in the driving pressurization step (S4), if the internal pressure of the fuel storage unit (10) measured by the fuel pressure sensor (32) is higher than a threshold value, the controller (31) may reduce or stop the flow rate of at least one of the gas supplied from the gas tank (21) to the fuel storage unit (10) through the gas supply pipe (22) and the vaporized fuel that is drawn out in a predetermined amount from the fuel supply pipe (61) and returned to the fuel storage unit (10).
[0109] Additionally, if the internal pressure of the fuel storage unit (10) measured by the fuel pressure sensor (32) is below a threshold value, the controller (31) can increase the flow rate of at least one so that the internal pressure of the fuel storage unit (10) is maintained above the threshold value.
[0110] Meanwhile, the above driving pressurization step (S4) may further include a predictive control step (S41) which processes data collected from various sensors including the fuel pressure sensor (32) by a data processing module, models the dynamic characteristics of the fuel storage unit (10) according to the repeated driving of the ship's LNG engine test device (1), and calculates an optimal valve opening and closing command by a predetermined algorithm based on the result of predicting the internal pressure change over a certain period of time based on the measured internal pressure of the fuel storage unit (10).
[0111] The above predictive control step (S41) can be understood as a step in which the controller (31) determines the degree of opening and closing of various valves according to a predetermined algorithm based on the internal pressure of the fuel storage unit (10) or data detected from various sensors. Specifically, in the above predictive control step (S41), the controller (31) models the dynamic characteristics of the fuel storage unit (10) by processing data collected in real time from the fuel pressure sensor (32) and various sensors in a data processing module. Subsequently, based on the measured internal pressure value of the fuel storage unit (10), the internal pressure change over a certain period of time is predicted, and a predetermined algorithm is applied according to the prediction result to issue an optimal opening and closing command for the gas volume control valve (23) and / or flow rate control valve (62).
[0113] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.
[0114] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention. Explanation of the symbols
[0115] 1: Marine LNG Engine Test Device 10: Fuel storage unit 20: Gas supply unit 21: Gas tank 22: Gas supply pipe 23: Gas volume control valve 30: Detector 31: Controller 32: Fuel pressure sensor 33: Fuel temperature sensor 34: Fuel level sensor 35: Transfer pressure sensor 36: Transfer temperature sensor 40: Transfer section 41: Transfer pipe 42: Pressure pump 43: Pressure valve 50: Fuel supply unit 51: Carburetor 52: Fuel supply pipe 53: Pressure valve 54: Buffer tank 60: Extraction unit 61: Discharge tube 62: Flow control valve 70: Engine
Claims
Claim 1 A test device for a marine LNG engine, comprising: a fuel storage unit for storing LNG fuel in a liquid state; a gas supply unit for supplying gas to the fuel storage unit; a sensing unit for detecting the state of the fuel storage unit and controlling the fuel to be discharged to the outside; a transfer unit for transferring the fuel discharged from the fuel storage unit in a liquid state; and a fuel supply unit for vaporizing the fuel transferred through the transfer unit and supplying it to the engine side, wherein the fuel is pressurized and discharged from the fuel storage unit to the engine by the pressure formed by the fluid supplied to the fuel storage unit, thereby enabling testing of whether the engine is operating normally. Claim 2 A test device for a marine LNG engine according to claim 1, wherein the gas supply unit comprises a gas tank for storing gas, a gas supply pipe fluidly connected from the outlet end of the gas tank to the front end of the fuel storage unit, and a gas volume control valve connected to the gas supply pipe for determining the flow rate of gas supplied to the fuel storage unit, and wherein the sensing unit maintains the internal pressure of the fuel storage unit higher than a threshold value by controlling the degree of opening and closing of the gas volume control valve. Claim 3 In paragraph 2, the sensing unit comprises a fuel pressure sensor that measures the internal pressure of the fuel storage unit and a controller that controls the degree of opening and closing of the gas volume control valve or the flow rate control valve according to the pressure measured by the fuel pressure sensor, wherein the controller reduces or closes the degree of opening and closing of the gas volume control valve when the internal pressure measured by the fuel pressure sensor is higher than a threshold value, and increases the degree of opening and closing of the gas volume control valve to maintain the internal pressure at an increased level when the internal pressure measured by the fuel pressure sensor is lower than or equal to a threshold value. Claim 4 In paragraph 3, the ship LNG engine test device further comprises an extraction unit formed to extract a predetermined amount of vaporized fuel from the fuel supply unit and return it to the fuel storage unit, wherein the extraction unit comprises an extraction pipe fluidly connected from one end of the fuel supply unit to the upper part of the fuel storage unit, and a flow control valve connected to the extraction pipe to determine the flow rate of the vaporized fuel extracted from the fuel supply unit and returned to the fuel storage unit, and wherein the sensing unit maintains the internal pressure of the fuel storage unit higher than a threshold value by controlling the degree of opening and closing of at least one of the gas volume control valve or the flow control valve. Claim 5 A test device for a marine LNG engine according to claim 4, wherein the transfer unit comprises a transfer pipe fluidly connected from the outlet end of the fuel storage unit to the front end of the fuel supply unit, and a pressure pump disposed at a predetermined position on the transfer pipe, wherein the pressure pump pressurizes the transferred liquid fuel to a level usable in the engine. Claim 6 A test device for a marine LNG engine according to claim 5, wherein the transfer unit does not additionally include a pressurizing means other than the pressure pump. Claim 7 A test device for a marine LNG engine according to claim 6, wherein the controller increases the degree of opening and closing of the gas volume control valve to increase the internal pressure of the fuel storage unit when the initial pressure of the fuel storage unit is formed, and during operation after the initial pressure of the fuel storage unit is formed, if the internal pressure measured by the fuel pressure sensor is higher than a threshold value, it decreases or closes the degree of opening and closing of the flow control valve, and if the internal pressure measured by the fuel pressure sensor is lower than a threshold value, it increases the degree of opening and closing of the flow control valve to maintain the internal pressure higher than a threshold value. Claim 8 A test device for a marine LNG engine according to claim 7, wherein the threshold value is the pressure of the fuel flowing into the pressure pump, which is the minimum pressure at which the LNG fuel can be maintained in a liquid state. Claim 9 A method for testing a marine LNG engine using a marine LNG engine test device according to any one of claims 1 to 8, comprising: an initial pressure forming step of supplying gas from a gas tank to a fuel storage unit through a gas supply pipe to increase internal pressure; a transfer step of transferring fuel leaked by the internal pressure of the fuel storage unit through a transfer pipe; a fuel supply step of vaporizing fuel pressurized by a pressure pump and supplying it to the engine side through a fuel supply pipe; and a driving pressurization step in which, when the internal pressure of the fuel storage unit is below a threshold value, a controller raises and maintains the internal pressure of the fuel storage unit above a threshold value. Claim 10 In the 9th, the driving pressurization step is characterized in that, when the internal pressure of the fuel storage unit measured by the fuel pressure sensor is higher than the threshold value, the controller reduces or stops the flow rate of at least one of the gas supplied from the gas tank to the fuel storage unit through the gas supply pipe and the vaporized fuel extracted in a predetermined amount from the fuel supply pipe and returned to the fuel storage unit, and when the internal pressure of the fuel storage unit measured by the fuel pressure sensor is lower than the threshold value, the controller increases the flow rate of at least one to maintain the internal pressure of the fuel storage unit higher than the threshold value.