Fuel Gas Heating System

Abstract

The present invention relates to a fuel gas heating system. The fuel gas heating system of the present invention comprises an engine section, a fuel supply section which supplies the fuel gas to the engine section, a fuel heating section which heats the fuel gas supplied to the engine section, a gas valve unit section which is provided in a gas valve unit room and controls the pressure and flow rate of the fuel gas supplied to the engine section, an outside air exhaust section which exhausts outside air sucked into the gas valve unit room for air circulation, a nitrogen gas supply section which generates, pressurizes and supplies nitrogen from a nitrogen generator, and a control section which controls the fuel gas heating system.

Description

[Technical field]

[0001] The present invention relates to a fuel gas heating system, and more particularly to a fuel gas heating system that uses an electric heating device to raise the temperature of fuel gas to a temperature required by an engine before supplying the fuel gas to the engine, thereby smoothly supplying the fuel gas to the engine. [Background technology]

[0002] Generally, engines and other combustion equipment installed on various ships use oils such as MDO (Marine Diesel Oil) and HFO (Heavy Fuel Oil) as fuel. However, such fuel oils have become the main culprits of environmental pollution due to the greenhouse gases and various harmful substances that are generated during combustion. In addition, when oil prices rise due to the depletion of fossil fuels or international instability, fuel costs will skyrocket, causing problems in ship operation.

[0003] In recent years, regulations on air pollution have become increasingly strict, and clean fuels such as liquefied natural gas (LNG), which has low sulfur oxide (Sox) and nitrogen oxide (NOx) content, have been attracting attention as an alternative energy source to fuel oil. LNGCs (LNG Carriers), which transport large quantities of LNG, are already using technology to use LNG stored in storage tanks as engine fuel.

[0004] Engines that use liquefied gas as fuel must pre-treat the liquefied gas to the pressure and temperature required by the engine before supplying it to the engine, rather than simply putting the liquefied gas into the engine and burning it.

[0005] Currently, when the fuel gas pipes of an LNG carrier are installed on the weather deck, the temperature of the fuel gas drops due to the influence of the outside air temperature.To prevent this temperature drop, electric heat tracing and insulation are applied to the fuel gas pipes.

[0006] In the above case, the piping length can reach up to 200m, and therefore, when applying electric heat tracing and insulation, a large amount of materials is required, which makes the installation expensive. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE PRESENT EMBODIMENT In order to solve the above problems, the present invention aims to provide a fuel gas heating system.

[0008] More specifically, the object is to provide a fuel gas heating system that can smoothly supply the required temperature of the engine by raising it at the front end of the engine using an electric gas heater.

[0009] Another object of the present invention is to provide a fuel gas heating system equipped with an electric gas heater that reduces the risk of explosion.

[0010] The technical problems of the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned can be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0011] In order to achieve the above-mentioned object, one aspect of the present invention provides a fuel gas heating system comprising an engine section, a fuel supply section which supplies the fuel gas to the engine section, a fuel heating section which heats the fuel gas supplied to the engine section, a gas valve unit section which is provided in a gas valve unit room and controls the pressure and flow rate of the fuel gas supplied to the engine section, an outside air exhaust section which exhausts outside air sucked into the gas valve unit room for air circulation, a nitrogen gas supply section which generates and pressurizes nitrogen using a nitrogen generator and supplies it, and a control section which controls the fuel gas heating system.

[0012] Preferably, the fuel heating section includes an electric gas heater formed of a double pipe, and is provided within the gas valve unit room.

[0013] Preferably, the electric gas heater has an electric coil provided in the inner tube of the double tube, and a heat-insulating filler is filled between the inner tube in which the electric coil is provided and between the inner tube and the outer tube to transfer heat from the electric coil of the inner tube.

[0014] Preferably, the electric gas heater further includes a nitrogen gas supply valve for supplying nitrogen gas, a leak detection pressure sensor for detecting the pressure of the nitrogen gas, and a gas pressure sensor for detecting the pressure of the fuel gas, and the nitrogen gas supply valve is opened to supply nitrogen gas to the inner tube of the double tube.

[0015] Preferably, the supply pressure of the nitrogen gas is higher than the supply pressure of the fuel gas, and when the supply pressure of the nitrogen gas is lower than the supply pressure of the fuel gas, the supply of the fuel gas is stopped.

[0016] Preferably, the electric gas heater may further include an air circulation fan for circulating air between the double pipe and the electric coil, an air circulation line for circulating air from one end of the electric gas heater to the other end, and a gas sensor for detecting leakage of the fuel gas.

[0017] Preferably, a gas sensor is disposed on the air circulation line, and when the gas sensor detects fuel gas, the supply of fuel gas is stopped.

[0018] Preferably, the engine section includes a gas temperature sensor that detects the temperature of fuel gas supplied to the engine section and controls the fuel heating section in response to the temperature of the fuel gas.

[0019] In order to achieve the above-mentioned object, another aspect of the present invention provides a method for operating a fuel gas heating system, comprising a first fuel supply step of supplying fuel gas from a fuel supply unit to a fuel heating unit, a fuel gas heating step of heating the supplied fuel gas, and a second fuel supply step of supplying the fuel gas heated in the fuel heating unit to an engine unit.

[0020] Preferably, the fuel gas heating step includes supplying fuel gas to an electric gas heater formed of a double tube, supplying fuel gas to an outer tube of the double tube, and heating an electric coil provided in an inner tube of the double tube to heat the fuel gas.

[0021] Preferably, the fuel gas heating step further includes a leakage detection step of detecting leakage or backflow of the fuel gas while the fuel gas is being heated.

[0022] Preferably, the leak detection step includes a nitrogen gas supply step of supplying nitrogen gas and an air circulation step of circulating air in the inner tube, and is performed by selecting either one of the nitrogen gas supply step and the air circulation step.

[0023] Preferably, the air circulation step periodically changes the air circulation direction.

[0024] Preferably, if a leak is detected in the leak detection step, the supply of fuel gas is stopped and the gas mode operation of the engine is stopped. Effect of the Invention

[0025] An object of the present invention configured as described above is to provide a fuel gas heating system.

[0026] Specifically, the present invention provides a fuel gas heating system that smoothly supplies the required temperature to the engine by raising it using an electric gas heater at the front end of the engine.

[0027] Another advantage is the provision of a fuel gas heating system including an electric gas heater that reduces the risk of explosion.

[0028] The technical problems of the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned can be clearly understood by those skilled in the art from the following description. [Brief description of the drawings]

[0029] [Figure 1] 1 is a schematic diagram of a fuel gas heating system according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The details of the objectives, technical configuration, and operation and effects of the present invention can be more clearly understood from the detailed description of the present invention based on the accompanying drawings.

[0031] The terms used in this specification are merely used to describe certain embodiments and are not intended to limit the present invention. For example, in this specification, "including" or "comprising" a certain component means that it may further include or comprise other components, without excluding other components, unless otherwise specified. Furthermore, when a description is made that a certain component is "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to the other component, but that other components may exist in between.

[0032] Hereinafter, the present invention will be described in detail using preferred embodiments of the present invention with reference to the accompanying drawings. The embodiments described below are provided to allow those skilled in the art to easily understand the technical concept of the present invention, and should not be construed as limiting the present invention. It is natural that the embodiments of the present invention can be applied in various ways by those skilled in the art.

[0033] FIG. 1 is a configuration diagram of a fuel gas heating system according to one embodiment of the present invention.

[0034] Referring to FIG. 1, the fuel gas heating system according to the present invention may include an engine unit, a fuel supply unit, a fuel heating unit, a gas valve unit, an outside air exhaust unit, a nitrogen gas supply unit and a control unit.

[0035] The engine section includes an engine that can run on LNG (Liquefied Natural Gas) as fuel, is arranged in an engine room (E / R), and may include one or more engines. For example, the engine section may include a first engine 100a and a second engine 100b, and the number of engines may be adjusted as needed.

[0036] In addition, the first engine 100a and the second engine 100b are equipped with a first gas temperature sensor 110a and a second gas temperature sensor 110b to measure the temperature of the fuel gas supplied to the engines in order to control the temperature of the fuel gas required by the engines.

[0037] The fuel supply unit supplies fuel gas to the engine unit and may include a fuel storage tank (not shown) that stores the fuel gas (LNG).

[0038] Specifically, the fuel supply unit supplies fuel gas to the first engine 100a and the second engine 100b via a main fuel supply line 400, and a master gas valve 410 that adjusts the supply of the fuel gas may be provided in the main fuel supply line 400.

[0039] The fuel heater heats the fuel gas supplied to the engine to a temperature required by the engine, and may be installed in a Gas Valve Unit Room (GVU room).

[0040] At this time, the gas valve unit room is a space classified as a gas hazardous area and must be located in an area isolated from the engine room (E / R). For safety reasons, periodic ventilation is required, and dry air must be exchanged 30 times per hour to prepare for gas leakage. Therefore, it is preferable that the gas valve unit room is configured to include an outside air exhaust part 500 that sucks in leaked gas or outside air and exhausts the circulated air to the outside.

[0041] In addition, the outside air exhaust unit 500 includes an exhaust fan, and a gas detection sensor may be provided at the front end of the exhaust fan so that gas leakage can be detected when it occurs.

[0042] The fuel heating unit is provided in a gas valve unit room (GVU room), and therefore should be constructed to prevent the risk of explosion. Therefore, the fuel heating unit is characterized by being constructed of an explosion-proof electric gas heater 200.

[0043] The electric gas heater 200 includes an electric coil 220, and heats the fuel gas by applying power to the electric coil 220. At this time, if the electric coil 220 and the fuel gas come into direct contact with each other, there is a risk of explosion, so it is necessary to configure the electric coil 220 so that they do not come into direct contact with each other.

[0044] Therefore, the electric gas heater 200 is preferably configured to include an electric coil 220 in the inner tube of a double tube 210. In order to improve the heat transfer efficiency of the electric coil 220, the double tube 210 may be filled with a heat-insulating filler 230.

[0045] Specifically, the heat-insulating filler 230 is configured to be filled in the inner pipe including the electric coil 220 and between the inner pipe and the outer pipe. By filling the heat-insulating filler 230 in the inner pipe and between the inner pipe and the outer pipe, the movement of the electric coil 220 can be prevented and the heat transfer efficiency can be improved.

[0046] Furthermore, a filter (not shown) can be provided at one end and the other end of the electric gas heater 200. By disposing a filter at one end and the other end of the electric gas heater 200, the heat-retaining filler 230 is prevented from flowing out of the electric gas heater 200.

[0047] In addition, the fuel heating unit further includes a means for detecting a fuel gas leak in order to reduce the risk of explosion. Specifically, the electric gas heater 200 further includes a nitrogen supply line 300 and a nitrogen gas supply valve 310 for supplying nitrogen gas, and a leak detection pressure sensor 250 for detecting the pressure of the nitrogen gas.

[0048] In addition, a fuel supply line 420 is provided for supplying the fuel gas heated by the electric gas heater 200 to the engine section, and a gas pressure sensor (not shown in the drawing) for detecting the pressure of the fuel gas is disposed on the fuel gas supply line 420.

[0049] At this time, the electric gas heater 200 can supply nitrogen gas to the inner pipe of the double pipe 210 in order to prevent the fuel gas from flowing back (leaking).

[0050] Specifically, nitrogen is generated and pressurized by a nitrogen generator inside the ship and supplied from a nitrogen gas supply unit (not shown), and the nitrogen gas supply valve 310 is opened to fill the inner pipe of the double pipe 210 with nitrogen gas.

[0051] That is, it is preferable that the supply pressure of the nitrogen gas supplied to the inner pipe of the double pipe 210 is higher than the supply pressure of the fuel gas.

[0052] At this time, if the nitrogen gas is supplied at a pressure higher than the fuel gas supply pressure, the nitrogen gas supply valve 310 is closed to stop the supply of nitrogen. However, if the nitrogen gas supply valve 310 remains open and not closed for a predetermined period of time or more, it is determined that the inner pipe of the double pipe 210 has been damaged and the nitrogen gas has leaked into the fuel gas piping.

[0053] In addition, by comparing the pressure of the gas pressure sensor (not shown in the drawing) with the pressure of the leak detection pressure sensor 250, if the supply pressure of the nitrogen gas is lower than the supply pressure of the fuel gas, it is determined that the fuel gas has leaked (backflowed) into the inner pipe of the double pipe 210.

[0054] As described above, if it is determined that fuel gas has leaked (backflowed) and nitrogen gas has leaked into the fuel gas piping, the master gas valve 410 of the main fuel supply line 400 is closed to stop the fuel supply, the gas mode operation of the first engine 100a and the second engine 100b of the engine section is stopped, and the fuel gas is discharged to the outside to prevent danger.

[0055] Furthermore, the electric gas heater 200 may further include an air circulation fan 240 for circulating air between the inner tube of the double tube 210 and the electric coil 220, an air circulation line (not shown in the drawing) for circulating air from one end of the electric gas heater 200 to the other end, and a gas sensor 260 for detecting leakage of fuel gas, and the gas sensor 260 is disposed on the air circulation line.

[0056] Specifically, nitrogen gas is not injected into the inner tube of the double tube 210, and the air inside the inner tube of the double tube 210 is circulated through an air circulation line, and if fuel gas is detected by the gas sensor 260 during circulation, it is determined that a leak has occurred.

[0057] At this time, in order to prevent the heat-retaining filler 230 from being biased in one direction, it is preferable to periodically change the air circulation flow.

[0058] If it is determined that fuel gas has leaked as described above, the master gas valve 410 of the main fuel supply line 400 is closed to stop the fuel supply, the gas mode operation of the first engine 100a and the second engine 100b of the engine section is stopped, and the fuel gas is discharged to the outside to prevent danger.

[0059] The fuel gas heated by the fuel heating unit is supplied to the gas valve unit through the fuel supply line 420. At this time, it is preferable that the gas valve unit controls the pressure and flow rate of the fuel gas supplied to the engine unit, and is provided in accordance with the number of engines in the engine unit.

[0060] Specifically, when the engine section includes a first engine 100a and a second engine 100b, the gas valve unit section includes a first gas valve unit (not shown in the drawing) and a second gas valve unit (not shown in the drawing), the fuel supply line 420 branches into a first-1 fuel supply line 420a and a second-1 fuel supply line 420b, the first-1 fuel supply line 420a is connected to the first gas valve unit, and the second-1 fuel supply line 420b is connected to the second gas valve unit.

[0061] In addition, the first gas valve unit is connected to the first engine 100a via a first-second fuel supply line 120a, and the second gas valve unit is connected to the second engine 100b via a second-second fuel supply line 120b.

[0062] At this time, the first-second fuel supply line 120a and the second-second fuel supply line 120b are arranged to pass through a gas valve unit room (GUV room) and an engine room (E / R).

[0063] The engine room (E / R) is classified as a Gas Safe Zone, and is an area that must be secured from the Gas Hazardous Zone. Therefore, direct entry and exit from the Gas Hazardous Zone to the Gas Safe Zone is prohibited (airlocks must be installed if necessary), and the fuel supply line (fuel supply pipe) passing through the Gas Safe Zone must be completely enclosed by a double pipe or duct. Therefore, it is preferable that the first-second fuel supply line 120a and the second-second fuel supply line 120b are formed of a double pipe.

[0064] The control unit controls the operation of the fuel gas heating system of the present invention, specifically, by controlling the flow of fuel gas and the operating mode of the engine using temperature and pressure information measured by sensors in the system.

[0065] The control unit may be placed in the gas valve unit room. However, since explosion-proofing is required when placing the control unit in the gas valve unit room, it is preferable to place the control unit in the engine room E / R.

[0066] Hereinafter, with reference to the fuel gas heating system according to the embodiment of the present invention described above, a method of operating the fuel gas heating system according to the embodiment of the present invention will be described.

[0067] The method of operating the fuel gas heating system includes a first fuel supply step of supplying fuel gas from a fuel supply unit to a fuel heating unit, a fuel gas heating step of heating the supplied fuel gas, and a second fuel supply step of supplying the fuel gas heated in the fuel heating unit to an engine unit.

[0068] In the first fuel supply step, LNG fuel, which is the fuel gas, is supplied to the engine section, and the fuel is supplied to the fuel heater section via the main fuel supply line 400.

[0069] In the fuel gas heating step, the fuel gas supplied to the fuel heating section is heated by an electric gas heater 200 formed of a double pipe 210 .

[0070] Specifically, the fuel gas is heated by heating the electric coil 220 in the inner tube of the double tube 210, and the fuel gas is supplied to the outer tube of the double tube 210, and the electric coil 220 is heated to heat the fuel gas to a temperature required by the engine.

[0071] The second fuel supply step supplies the fuel gas heated through the fuel gas heating step to the engine section, and the engine section to which the fuel is supplied is operated in a gas mode.

[0072] Specifically, the heated fuel gas is supplied to the first gas valve unit and the second gas valve unit via the first-1 fuel supply line 420a and the second-1 fuel supply line 420b, and is supplied to the first engine 100a and the second engine 100b via the first-2 fuel supply line 120a and the second-2 fuel supply line 120b. The first engine 100a and the second engine 100b, which have received the fuel, operate using the supplied fuel gas.

[0073] Meanwhile, in the fuel gas heating step, a fuel gas leakage detection step is performed simultaneously to prevent leakage of the fuel gas when the fuel gas heating step is performed. If the fuel gas leaks into the inner pipe of the double pipe 210 in which the electric coil is arranged, there is a risk of explosion upon contact with the electric coil, so it is preferable to always detect leakage while the fuel gas is being supplied.

[0074] The step of detecting the leak includes a nitrogen gas supply step of supplying nitrogen gas and an air circulation step of circulating the air in the inner tube, and it is preferable to selectively carry out either the nitrogen gas supply step or the air circulation step.

[0075] In the nitrogen gas supplying step, nitrogen gas is supplied to the electric gas heater 200, and leakage can be detected based on the supply pressure of the nitrogen gas.

[0076] Specifically, while fuel gas is being supplied to the outer tube of the electric gas heater 200 formed of the double tube 210, the nitrogen gas supply valve 310 is opened to supply nitrogen gas to fill the inner tube of the double tube 210.

[0077] At this time, the nitrogen gas is supplied at a pressure higher than the supply pressure of the fuel gas, and when the supply pressure of the nitrogen gas becomes higher than the supply pressure of the fuel gas, the nitrogen gas supply valve 310 is closed to stop the supply of nitrogen gas.

[0078] However, if the supply pressure of the nitrogen gas is lower than the supply pressure of the fuel gas, it is determined that the combustion gas has backflowed (leaked).

[0079] Also, if the nitrogen gas supply valve 310 is left open for a predetermined time or more without being closed, it is determined that the inner pipe of the double pipe 210 is broken and the nitrogen gas leaks into the fuel gas piping.

[0080] If it is determined that fuel gas is leaking (backflowing) as described above and nitrogen gas is leaking into the fuel gas piping, the master gas valve 410 of the main fuel supply line 400 is closed to stop the fuel supply, and the gas mode operation of the first engine 100a and the second engine 100b of the engine section is controlled to be stopped.

[0081] In addition, in order to detect leakage while the fuel gas is being heated, the air circulation step does not inject nitrogen gas into the inner tube of the double tube 210, but circulates the air inside the inner tube of the double tube 210 via an air circulation line, and if fuel gas is detected by the gas sensor 260 during circulation, it can be determined that a leakage has occurred.

[0082] At this time, it is preferable to periodically change the air circulation flow in order to prevent the heat-retaining filler 230 from being biased in one direction. For example, when air is circulated from one end of the electric gas heater to the other end, it is preferable to change the air circulation flow so that air circulates from the other end to the one end after a predetermined time has elapsed, and to change the air flow in accordance with a predetermined period.

[0083] As described above, if a leak is detected, the master gas valve 410 is closed to stop the fuel supply, and the first engine 100a and the second engine 100b of the engine section are controlled to stop gas mode operation.

[0084] In addition, when the supply of fuel gas and the gas mode operation of the engine are stopped, it is preferable to discharge the residual fuel gas remaining in the fuel supply line, the fuel heating unit, the engine unit, etc. to the outside via the outside air discharge unit 500.

[0085] Thus, the present invention has the advantage of providing a fuel gas heating system which smoothly supplies the required temperature to the engine by raising it at the front end of the engine using an electric gas heater.

[0086] Furthermore, by controlling the temperature of the fuel gas immediately prior to delivery to the engine, the amount and cost of thermal equipment used to maintain the temperature of the fuel gas can be reduced.

[0087] In addition, the application of a double tube to the electric gas heater reduces the risk of explosion, and the leakage detection means detects the leakage of fuel gas and controls the operating mode of the engine, thereby improving the stability of the fuel gas heating system.

[0088] The above description is merely illustrative of the technical idea of ​​the present invention, and a person having ordinary knowledge in the technical field to which the present invention belongs may make various modifications, changes, and substitutions without departing from the essential characteristics of the present invention. Therefore, the embodiments and accompanying drawings disclosed in the present invention are for the purpose of explaining, not limiting, the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments and accompanying drawings. The scope of protection of the present invention should be interpreted according to the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

Claims

1. In a fuel gas heating system, Engine section: a fuel supply unit for supplying fuel gas to the engine unit; a fuel heating unit that heats the fuel gas supplied to the engine unit; a gas valve unit section provided in the gas valve unit room and controlling the pressure and flow rate of fuel gas supplied to the engine section; an outside air exhaust unit for exhausting the outside air sucked into the gas valve unit room for air circulation; a nitrogen gas supply unit that generates and pressurizes nitrogen from a nitrogen generator and supplies it; A control unit for controlling the fuel gas heating system; The fuel heating unit includes an electric gas heater formed of a double pipe and is installed in a gas valve unit room; The electric gas heater includes an electric coil provided in an inner tube of the double tube, In order to transfer heat from the electric coil of the inner pipe, a heat-insulating filler is filled inside the inner pipe equipped with the electric coil and between the inner pipe and the outer pipe. Fuel gas heating system.

2. the electric gas heater includes a nitrogen gas supply valve for supplying nitrogen gas; a leak detection pressure sensor that detects the pressure of nitrogen gas; A gas pressure sensor that detects the pressure of the fuel gas; The nitrogen gas supply valve is opened to supply nitrogen gas to the inner pipe of the double pipe. The fuel gas heating system of claim 1 .

3. The supply pressure of the nitrogen gas is higher than the supply pressure of the fuel gas, and when the supply pressure of the nitrogen gas is lower than the supply pressure of the fuel gas, the supply of the fuel gas is stopped.

3. The fuel gas heating system of claim 2.

4. The electric gas heater comprises: an air circulation fan for circulating air between the double pipe and the electric coil; an air circulation line for circulating air from one end of the electric gas heater to the other end; A gas sensor for detecting leakage of the fuel gas is further provided. The fuel gas heating system of claim 1 .

5. the gas sensor is disposed in the air circulation line, and when the gas sensor detects fuel gas, the supply of fuel gas is stopped.

5. The fuel gas heating system of claim 4.

6. the engine section includes a gas temperature sensor; The gas temperature sensor detects the temperature of the fuel gas supplied to the engine section, The fuel heating unit is controlled in accordance with the temperature of the fuel gas. The fuel gas heating system of claim 1 .

7. 1. A method for operating a fuel gas heating system, comprising: a first fuel supply step of supplying a fuel gas from a fuel supply unit to a fuel heating unit; a fuel gas heating step of heating the supplied fuel gas; a second fuel supply step of supplying the fuel gas heated by the fuel heating unit to an engine unit; The fuel gas heating step includes supplying the fuel gas to an electric gas heater formed of a double pipe, supplying the fuel gas to an outer pipe of the double pipe, and heating an electric coil provided in an inner pipe of the double pipe to heat the fuel gas. A method for operating a fuel gas heating system.

8. The fuel gas heating step further includes a leakage detection step of detecting leakage or backflow of the fuel gas during heating of the fuel gas.

8. A method for operating a fuel gas heating system according to claim 7.

9. The leak detection step includes a nitrogen gas supply step of supplying nitrogen gas; An air circulation step for circulating air in the inner tube; The nitrogen gas supply step and the air circulation step are selected and carried out.

9. A method for operating a fuel gas heating system according to claim 8.

10. The air circulation step periodically changes the direction of air circulation.

10. A method for operating a fuel gas heating system according to claim 9.

11. If a leak is detected in the leak detection step, the supply of fuel gas is stopped and the gas mode operation of the engine is stopped. A method for operating a fuel gas heating system according to claim 8.

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