Gas supply system of a gas engine or dual-fuel engine and method for operating the same

Description

[0001] The invention relates to a gas supply and inerting system for a gas engine or dual-fuel engine. Furthermore, the invention relates to a method for operating the gas supply system.

[0002] In a gas engine and a dual-fuel engine, a gaseous fuel is burned as fuel in gas-fuel operation. The respective engine can be supplied with the gaseous fuel via a gas supply system. Such a gas supply system has a tank for holding gaseous fuel, a gas control station for supplying the engine with gaseous fuel at a constant gas pressure depending on the required engine power, and a double-walled gas line extending from the gas control station to the engine cylinders.

[0003] The double-walled gas line of the gas supply and inerting system has an inner pipe through which the gas flows toward the engine. Furthermore, the double-walled gas line of the gas supply system has an outer pipe that surrounds at least some of the inner pipe and flows toward the gas control station to vent any potential gas leaks with the aid of purge air. The inner pipe and outer pipe define a leakage flow channel through which the purge air flows in a countercurrent direction to the inner pipe.

[0004] The gas control station of such a gas supply system is also called a gas supply room.

[0005] During purging operation of a gas engine, and especially when a dual-fuel engine is switched from gaseous fuel operation to liquid fuel operation, it is necessary to purge the lines previously carrying the gaseous fuel with inert gas. For engines known from practice, this requires complex piping for inert gas purge lines in the engine area. This is a disadvantage.

[0006] EP 2 952 727 A1 discloses a gas supply system for a dual-fuel engine. A double-walled line extends to the cylinders of the dual-fuel engine, comprising an inner tube and an outer tube that at least partially surrounds the inner tube. Fuel can be guided toward the cylinders via the inner tube of the double-walled line. The gas supply system disclosed therein further comprises an inert gas purge line and a shut-off valve associated with the inert gas purge line. When the shut-off valve is open, inert gas can be guided toward the cylinders via the inert gas purge line and the outer tube of the double-walled gas line.

[0007] EP 2 818 674 A1 and DE 10 2015 214 563 B3 disclose further prior art.

[0008] There is therefore a need for a gas supply system for a gas engine or a dual-fuel engine in which it is possible to purge the gaseous fuel-carrying pipes with inert gas, with little design effort and without the need for complex piping of an inert gas purge line in the area of ​​the engine.

[0009] Based on this, the present invention is based on the object of creating a novel gas supply system of a gas engine or dual-fuel engine and a method for operating the same.

[0010] According to the invention, the object is achieved by a gas supply system of a gas engine or dual-fuel engine according to claim 1.

[0011] The gas supply system according to the invention comprises a gas control station which serves to supply the engine in a gas fuel operation thereof with a gaseous fuel of constant gas pressure depending on a requested engine power.

[0012] The gas supply system according to the invention further comprises a double-walled gas line extending from the gas control station to the cylinders of the engine, which double-walled gas line has an inner tube and an outer tube surrounding the inner tube at least in sections, wherein in gas fuel operation the inner tube of the double-walled gas line can be flowed through by the gaseous fuel starting from an end of the double-walled gas line on the gas control station side in the direction of an end of the double-walled gas line on the engine side.

[0013] In the area of ​​the gas control station, a gas line extends to the gas control station-side end of the double-walled gas line, into which at least one gas shut-off valve is integrated. This gas line merges into the inner pipe of the double-walled gas line or provides the same. In the area of ​​the gas control station, at least one vent line with a vent valve integrated into the respective vent line branches off from the gas line between the at least one gas shut-off valve and the gas control station-side end of the double-walled gas line.

[0014] The gas supply system according to the invention further comprises an inert gas purge line and a shut-off valve associated with the inert gas purge line, wherein, in a purge operation of the engine with the first shut-off valve open, inert gas can be supplied via the inert gas purge line to the outer pipe of the double-walled gas line at the gas control station-side end of the double-walled gas line, which inert gas flows through the outer pipe in the direction of the engine-side end of the double-walled gas line, passes into the inner pipe there and flows back via the inner pipe in the direction of the gas control station-side end of the double-walled gas line in order to exit therefrom, namely in such a way that, with the vent valve open and the gas shut-off valve closed, the inert gas escaping from the double-walled gas line at the gas control station-side end during purge operation of the engine can be discharged via the respective vent line.

[0015] The present invention proposes a gas supply system in which inert gas can be supplied to the double-walled gas line, whose inner pipe is traversed by gaseous fuel during gas-fuel operation, via the gas control station-side end of the double-walled gas line during purge operation. This inert gas initially flows via the outer pipe, crosses from the outer pipe into the inner pipe in the region of the engine-side end, and then flows back via the inner pipe toward the gas control station-side end, from where it is discharged. This makes it possible to dispense with the previously required, complex piping for an inert gas purge line in the engine area.

[0016] According to an advantageous development of the invention, a valve is provided at the engine-side end of the double-walled gas line, which valve allows the inert gas to pass from the outer tube of the double-walled gas line into the inner tube of the double-walled gas line during engine purge operation. This valve can ensure that, on the one hand, the inert gas can pass from the outer tube to the inner tube during engine purge operation, and, on the other hand, the fuel gas can prevent the passage of the fuel gas from the inner tube to the outer tube during gas operation. This valve can be, for example, a check valve or an actively switchable valve.

[0017] According to an advantageous development, a pressure sensor is attached to the double-walled gas line, which detects a pressure drop in a double-walled gas line filled with inert gas. This allows for a simple and reliable leak test for the double-walled gas line.

[0018] Methods for operating the gas supply system are defined in claims 6, 7 and 8.

[0019] Preferred developments of the invention will become apparent from the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail, without being limited thereto, with reference to the drawings. Herein: Fig. 1 shows a gas supply system according to the invention for a gas engine or dual-fuel engine in a first state, Fig. 2 shows the gas supply system in a second state, and Fig. 3 shows detail III of the Fig. 2 .

[0020] The invention relates to a gas supply system for an engine designed as a gas engine or dual-fuel engine, which is used in particular on a ship. Furthermore, the invention relates to a method for operating such a gas supply system.

[0021] Fig. 1 and 2 show an embodiment of a preferred gas supply system 10 in the sense of the present invention together with an engine 11 designed as a dual-fuel engine. The engine 11 is arranged in an engine room 12.

[0022] The engine 11, designed as a dual-fuel engine or pure gas engine, has several cylinders 13 in which a gaseous fuel is combusted during gaseous fuel operation of the engine 11. In liquid fuel operation, a liquid fuel, such as diesel fuel, can be combusted in the cylinders 13 of the engine 11.

[0023] Fig. 1 further shows a generator 14 arranged in the engine room 12, which can be coupled to the engine 11 via a clutch 15. When the clutch 15 is engaged, the generator 14 can be driven by the engine 11, for example, to generate electrical energy. The engine 11 can also be used to provide propulsion power to another output, such as a ship's propeller.

[0024] In gaseous fuel operation, the gaseous fuel is supplied to the cylinders 13 of the engine 11 via the gas supply system 10. The gas supply system 10 has a tank (not shown) for supplying the gaseous fuel.

[0025] Furthermore, the gas supply system 10 has a gas control station, which is part of the aforementioned gas supply unit 16. The gas control station 16 serves to supply the engine 11 with gaseous fuel, specifically with gaseous fuel of constant gas pressure depending on the requested engine power.

[0026] Fig. 1 shows a gas line 17 which extends from the tank (not shown) in the direction of the engine 11, wherein this gas line 17 is part of a double-walled gas line 18 between the gas control station 16 and the engine 11. In the area of ​​the double-walled gas line 18, the gas line 17 forms an inner pipe 18a of the double-walled gas line 18, wherein this inner pipe 18a of the double-walled gas line 18 is partially surrounded by an outer pipe 18b.

[0027] The inner pipe 18a and the outer pipe 18b of the double-walled gas line 18 form separate flow channels.

[0028] The double-walled gas line 18 has a gas control station-side end 19 and an engine-side end 20. During gas fuel operation of the engine 11, gaseous fuel flows through the double-walled gas line 18, starting from the gas control station-side end 19 in the direction of the engine-side end 20, namely the inner tube 18a of the double-walled gas line 18.

[0029] Fig. 1 shows gas shut-off valves 21 installed in the area of ​​the gas control station 16. When the engine 11 is operated in gaseous fuel mode, these gas shut-off valves 21 are open. Viewed in the flow direction of the gaseous fuel, upstream of the gas shut-off valves 21, assemblies of a pressure regulator 22 are shown, via which the constant gas pressure of the gaseous fuel can be provided. Furthermore, Fig. 1 vent valves 29 installed in the area of ​​the gas control station 16, which interact with vent lines 30.

[0030] In the Fig. 1 and 2 In the gas supply system 10 shown, it is provided that in gas fuel operation, the outer pipe 18b of the double-walled gas line 18 is flowed through by purge air to discharge any gas leakage that may be present, starting from the engine-side end 20 in the direction of the gas control station-side end 19 of the double-walled gas line 18, so that accordingly in gas fuel operation in the gas supply system 10 of the Fig. 1 and 2 the inner pipe 18 and the outer pipe 18b are flowed through in opposite directions. The purge air can be supplied to the outer pipe 18b at the engine-side end 20 of the double-walled gas line 18 via a purge air supply line 23. The purge air can exit the double-walled gas line 18 at the gas control station-side end 19 and be discharged via a purge air discharge line 24.

[0031] In the gas supply system 10 according to the invention, it is provided that an inert gas purge line 25 is present, specifically with a first shut-off valve 26 assigned to the inert gas purge line 25. Then, when the purge air supply line 23 and the purge air outlet line 24 are present, a second shut-off valve 27 is assigned to the purge air supply line 23 and a third shut-off valve 28 is assigned to the purge air outlet line 24.

[0032] In gas fuel operation, the second shut-off valve 27 and the third shut-off valve 28 are both open, whereas the first shut-off valve 26 is closed in gas fuel operation. Then, when there is no gas fuel operation of the engine 10, but rather a purge operation, for example to convert the dual-fuel engine from gas fuel operation to liquid fuel operation, the first shut-off valve 26 is opened, so that inert gas can then be supplied via the inert gas purge line 25 to the outer pipe 18b of the double-walled gas line 18 at the gas control station-side end 19 of the double-walled gas line 18, which inert gas flows through the outer pipe 18b in the direction of the engine-side end 20 of the double-walled gas line 18, there passes from the outer pipe 18b into the inner pipe 18a and flows via the inner pipe 18a back in the direction of the gas control station-side end 19 of the double-walled gas line 18 in order to exit therefrom, orto be discharged there via the venting device 29, 30. When the purge air supply line 23 and the purge air discharge line 24 are present, the second shut-off valve 27 and the third shut-off valve 28 are both closed during purge operation. Likewise, the two gas shut-off valves 21 are closed during purge operation.

[0033] As described above, the two gas shut-off valves 21 are provided in the area of ​​the gas control station 16. Likewise, several vent valves 29 are provided, wherein in the illustrated embodiment, two vent valves 29 are assigned to a vent line 30 that branches off from the gas line 17 between the or each gas shut-off valve 21 and the gas control station-side end 19 of the double-walled gas line 18.

[0034] In purging mode, as explained above, the gas shut-off valves 21 are closed, but the vent valves 29, which are assigned to the vent lines 30, which branch off from the gas line 17 between the gas shut-off valves 21 and the gas control station-side end 19 of the double-walled gas line 18, are open in purging mode of the engine 11, so that the inert gas escaping from the gas control station-side end of the double-walled gas line 18, namely from the inner pipe 18a thereof, can be discharged via the vent line 30.

[0035] Then, when, as in Fig. 1 When, as shown, the engine 11 is operated in gas mode, the first shut-off valve 26 is closed and no inert gas is supplied to the engine 11. The gas shut-off valves 21 are open so that gaseous fuel can be supplied to the cylinders 13 of the engine 11 via the double-walled gas line 18 via the inner tube 18a.

[0036] When the outer pipe 18b is purged with purge air during gas-fuel operation, the two shut-off valves 27 and 28 are opened, so that the purge air can be supplied to the engine-side end 20 of the double-walled gas line 18, namely the outer pipe 18b, via the purge air supply line 23, and the purge air exiting the double-walled gas line 18 at the gas control station-side end 19, namely the outer pipe 18b, can then be discharged via the purge exhaust air line 24. During gas-fuel operation, the vent valves 29 are closed.

[0037] During purging operation, the first shut-off valve 26 is open, the second shut-off valve 27 and the third shut-off valve 28 are both closed. The gas shut-off valves 21 are also closed. At least one of the vent valves 29, which is assigned to the vent lines 30 branching off from the gas line 17 between the gas shut-off valves 21 and the gas control station-side end 19 of the double-walled gas line 18a, is open.

[0038] Thus, during purging operation, with the shut-off valve 26 open, inert gas can be supplied to the outer pipe 18b via the gas control station-side end 19 of the double-walled gas line 18, with the inert gas then flowing via the outer pipe 18b toward the engine-side end 20 of the double-walled gas line 18 and there passing into the inner pipe 18a. In the inner pipe 18a, the inert gas flows from the engine-side end 20 back to the gas control station-side end 19 of the double-walled gas line 18, exits the double-walled gas line 18 there, and is discharged via the vent line 30, which branches off from the gas line 17 upstream of the gas shut-off valves 21, as seen in the direction of flow of the inert gas.

[0039] As best seen in detail III of the Fig. 3 can be removed, a valve 31 is provided at the engine-side end 20 of the double-walled gas line 18, which, during purging operation, allows the inert gas to pass from the outer tube 18b of the double-walled gas line 18 into the inner tube 18a of the double-walled gas line. In the illustrated embodiment, this valve 31 is a check valve. When, in gaseous fuel operation, the gaseous fuel flows through the inner tube 18a in the opposite direction, the check valve 31 is closed.

[0040] A switchable valve can also be used as valve 31. However, a check valve is structurally simpler.

[0041] A pressure sensor 32 can be assigned to the double-walled gas line 18 to measure the pressure in the double-walled gas line 18, specifically in the outer pipe 18b. This can be used, in particular, to close the first shut-off valve 26 and then monitor the pressure in the double-walled gas line 18 when the double-walled gas line 18 is filled with inert gas during purging operation, both in the inner pipe 18a and the outer pipe 18b. If a pressure drop is detected, a leak in the double-walled gas line 18 can be concluded. This functionality requires a switchable valve as valve 31. Valve 31 must be closed before valve 26. The pressure drop is then monitored in 18b.

[0042] Although in Fig. 1 and 2the purge air supply line 23 and the purge air discharge line 24 with the two shut-off valves 27 and 28 are shown, these assemblies can also be omitted. In this case, the outer tube 18b can be filled with inert gas during gaseous fuel operation. The pressure of the inert gas in the outer tube 18b is then higher than the pressure of the gaseous fuel in the inner tube 18a. By omitting the purge air supply line 23 and the purge air discharge line 24, a particularly simple structure of the gas supply system 10 can be ensured. The outer tube 18b is then permanently filled with inert gas. This can then be used to purge the inner tube 18a during purge operation, for example when switching from gaseous fuel operation to liquid fuel operation on a dual-fuel engine.

[0043] The invention further relates to methods for operating a gas supply system 10, wherein the shut-off valve 26 is closed during gaseous fuel operation and the shut-off valve 26 is open during purge operation. If the purge air supply line 23 and the purge air discharge line 24 are present, the shut-off valves 27 and 28 are both open during gaseous fuel operation and both are closed during purge operation.

[0044] Then, when no gaseous fuel is burned in the engine 11 during purge operation and the two gas shut-off valves 21 are closed, and when the double-walled gas line 18 has been filled with inert gas by opening the shut-off valve 26, the first shut-off valve 26 can be closed and then the pressure in the double-walled gas line 18 can be monitored with a pressure sensor 32, wherein a leak in the double-walled gas line is then concluded in the event of a pressure change. List of reference symbols

[0045] 10Gas supply system 11Engine 12Engine room 13Cylinder 14Power take-off / generator 15Coupling 16Gas control station 17Gas line 18Double-walled gas line 18aInner pipe 18bOuter pipe 19Gas control station end 20Engine end 21Gas shut-off valve 22Pressure regulator 23Purge air supply line 24Purge air outlet 25Inert gas purge line 26Shut-off valve 27Shut-off valve 28Shut-off valve 29Vent valve 30Vent line 31Valve 32Pressure sensor

Claims

1. A gas supply system (10) of a gas engine or dual fuel engine (11), having a gas regulating station (16) for supplying the engine (11) in a gas fuel mode of the same with a gaseous fuel of constant gas pressure dependent on a requested engine output, having a double-walled gas line (18) extending from the gas regulating station (16) to cylinders (13) of the engine (11), which comprises an inner pipe (18a) and an outer pipe (18b) surrounding the inner pipe (18a) at least in sections, wherein in the region of the gas regulating station (16) a gas line (17) extends to the gas regulating station-side end (19) of the double-walled gas line (18), which is integrated in the at least one gas shut-off valve (21), wherein this gas line (17) merges into the inner pipe (18a) of the double-walled gas line (18) or provides the same, wherein in the region of the gas regulating station (16) at least one vent line (30) with a vent valve (29) integrated in the respective vent line (30) branches off the gas line (17) between the at least one gas shut-off valve (21) and the gas regulating station-side end (19) of the double-walled gas line (18), wherein in the gas fuel mode the inner pipe (18a) of the double-walled gas line (18), emanating from a gas regulating station-side end (19) of the double-walled gas line (18) can be flowed through by the gaseous fuel in the direction of an engine-side end (20)of the double-walled gas line (18), having an inert gas purging line (25) and a first shut-off valve (26) assigned to the inert gas purging line (25), wherein in a purging mode of the engine (11) with opened first shut-off valve (26), inert gas can be supplied via the inert gas purging line (25) to the outer pipe (18b) of the double-walled gas line (18) on the gas regulating station-side end (19) of the double-walled gas line (18), which flows through the outer pipe (18b) in the direction of the engine-side end (20) of the double-walled gas line (18), there passes into the inner pipe (18a) and via the inner pipe (18a) flows back in the direction of the gas regulating station-side end (19) of the double-walled gas line (18), in order to exit from the same, namely in such a manner that with opened vent valve (29) and closed gas shut-off valve (21) the inert gas exiting at the gas regulating station-side end (19) from the double-walled gas line (18) in the purging mode of the engine (11), can be discharged via the respective vent line (30).

2. The gas supply system according to Claim 1, characterised in that for supplying the engine (11) with gaseous fuel the first shut-off valve (26) is closed.

3. The gas supply system according to Claim 1 or 2, characterised in that a pressure sensor (32) acts on the double-walled gas line (18) via which a pressure drop of the double-walled gas line (18) filled with inert gas is detectable.

4. The gas supply system according to any one of the Claims 1-3, characterised in that at the engine-side end (20) of the double-walled gas line (18) a valve (31) is provided, which in the purging mode allows the inert gas from the outer pipe (18b) of the double-walled gas line (18) to pass into the inner pipe (18a) of the double-walled gas line (18).

5. The gas supply system according to any one of the Claims 1-4, characterised by the outer pipe (18b) of the double-walled gas line (18) in the gas fuel mode of the engine for discharging a gas leakage in the direction of the gas regulating station (16) can be flowed through by purging air, wherein the purging air can be supplied to the outer pipe (18b) at the engine side-end (20) of the double-walled gas line (18) via a purging air supply line (23), and wherein the purging air can be discharged from the outer pipe (18b) at the gas regulating station-side end (19) of the double-walled gas line (18) via a purging air discharge line (24), a second shut-off valve (27) assigned to the purging air supply line (23) and a third shut-off valve (28) assigned to the purging air discharge line (24), wherein the second and third shut-off valve (27, 28) are closed in the purging mode of the engine (11) and opened in the gas fuel mode of the engine (11).

6. A method for operating a gas supply system according to any one of the Claims 1-5, characterised in that in particular when in the gas fuel mode of the engine (11) gaseous fuel is combusted in the engine, the first shut-off valve (26) is closed and the second and third shut-off valve (27, 28), if any, are opened.

7. The method for operating a gas supply system according to Claims 1-5 or method according to Claim 6, characterised in that in particular when in the purging mode of the engine (11) no gaseous fuel is combusted in the engine, in particular with a dual fuel engine for the transition into a liquid fuel mode of the engine, the first shut-off valve (26) is opened and the second and third shut-off valve (27, 28), if any, are closed.

8. The method for operating a gas supply system according to Claim 3 or method according to Claim 6 or 7, characterised in that in particular when in the purging mode of the engine (11) no gaseous fuel is combusted in the engine, in particular with a dual fuel engine for the transition into a liquid fuel mode of the engine, the double-walled gas line was filled with inert gas, the first shut-off valve (26) is then closed and the pressure in the double-walled gas line (18) is then monitored via the pressure sensor (32).