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EP-4739898-A1 - FUEL SUPPLY SYSTEM, POWER GENERATING UNIT, POWER PLANT AND METHOD OF PERFORMING A FUNCTIONALITY TEST OF A LEAKAGE SPACE OF A FUEL SUPPLY SYSTEM

EP4739898A1EP 4739898 A1EP4739898 A1EP 4739898A1EP-4739898-A1

Abstract

The fuel supply system for an internal combustion engine (10) comprises a double-walled fuel supply line (1) having an inner pipe (2) for conveying pressurized fuel and an outer pipe (3) arranged around the inner pipe (2) such that an annular leakage space (4) is formed between the inner pipe (2) and the outer pipe (3), the leakage space (4) being open to the outside of the leakage space (4) for continuous venting of the leakage space (4). The leakage space (4) is connected to the outside via flow restriction means (6), and the fuel supply system comprises means (7) for monitoring the pressure in the leakage space (4).

Inventors

  • SMEDS, Anders
  • MÄKINEN, Jani

Assignees

  • Wärtsilä Finland Oy

Dates

Publication Date
20260513
Application Date
20230704

Claims (20)

  1. 1 . A fuel supply system for an internal combustion engine (10), the fuel supply system comprising a double-walled fuel supply line (1 ) having an inner pipe (2) for conveying pressurized fuel and an outer pipe (3) arranged around the inner pipe (2) such that an annular leakage space (4) is formed between the inner pipe (2) and the outer pipe (3), the leakage space (4) being open to the outside of the leakage space (4) for continuous venting of the leakage space (4), wherein the leakage space (4) is connected to the outside via flow restriction means (6), and the fuel supply system comprises means (7) for monitoring the pressure in the leakage space (4).
  2. 2. A fuel supply system according to claim 1 , wherein the flow restriction means (6) comprise at least one orifice.
  3. 3. A fuel supply system according to claim 2, wherein the flow restriction means (6) comprise a single orifice having a cross-sectional area of 0.1- 10 mm 2 , or the flow restriction means comprise two or more orifices allowing parallel flow from the leakage space, and the combined cross- sectional area of the orifices is 0.1-10 mm 2 .
  4. 4. A fuel supply system according to claim 3, wherein the cross-sectional area of the orifice(s) is 0.2-5.0 mm 2 .
  5. 5. A fuel supply system according to any of the preceding claims, wherein the fuel supply system comprises means (8, 9) for introducing pressurized non-flammable gas into the leakage space (4) for testing the functionality of the leakage space (4).
  6. 6. A fuel supply system according to claim 5, wherein the pressurized nonflammable gas is air.
  7. 7. A fuel supply system according to any of the preceding claims, wherein the inner pipe (2) is configured to convey gaseous fuel.
  8. 8. A power generating unit comprising a piston engine (10) and a fuel supply system according to any of the preceding claims.
  9. 9. A power generating unit according to claim 8, wherein the means (7) for monitoring the pressure in the leakage space (4) are operatively connected to a control unit (19) that is configured to monitor the pressure in the leakage space (4) during operation of the engine (10).
  10. 10. A power generating unit according to claim 9, wherein the control unit (19) is configured to trigger an alarm when the pressure in the leakage space (4) exceeds a predetermined alarm threshold.
  11. 11. A power generating unit according to claim 9 or 10, wherein the power generating unit is configured to shut down the engine (10) when the pressure in the leakage space (4) exceeds a predetermined shutdown threshold.
  12. 12. A power generating unit according to any of claims 8-11 , wherein the power generating unit is configured to perform a functionality test of the leakage space (4) when predetermined conditions are met and/or upon manual activation of the functionality test.
  13. 13. A power generating unit according to any of claims 8-12, wherein the power generating unit is configured to perform a functionality test of the leakage space (4) when the power generating unit is switched to a standby mode.
  14. 14. A power generating unit according to any of claims 8-13, wherein the power generating unit is configured to perform a functionality test of the leakage space (4) at predetermined intervals when the power generating unit is in a standby mode.
  15. 15. A power generating unit according to any of claims 8-14, wherein the power generating unit is configured to perform a functionality test of the leakage space (4) at predetermined intervals when the engine (10) is running.
  16. 16. A power generating unit according to claims 11 and 15, wherein the shutdown threshold is configured to be higher during the functionality test of the leakage space (4) than during other operation of the power generating unit.
  17. 17. A power generating unit according to any of claims 12-16, wherein the power generating unit is configured to perform the functionality test by introducing pressurized non-flammable gas into the leakage space (4) and by monitoring the pressure in the leakage space (4) after the supply of the pressurized non-flammable gas into the leakage space (4) has been terminated to detect too fast or too slow decreasing of the pressure.
  18. 18. A power generating unit according to any of claims 12-17, wherein the engine (10) is a four-stroke engine.
  19. 19. A power generating unit according to any of claims 12-18, wherein the engine (10) is arranged within a building (12) and the power generating unit comprises a venting pipe (13) connecting the leakage space (4) to the outdoors.
  20. 20. A power generating unit according to claim 19, wherein the power generating unit comprises a degassing valve (14), which is configured to allow the inner pipe (2) of the fuel supply line (1 ) to be connected to the venting pipe (13) to allow discharging of fuel from the inner pipe (2) into the venting pipe (13) upon shutdown of the engine (10).

Description

Fuel supply system, power generating unit, power plant and method of performing a functionality test of a leakage space of a fuel supply system Technical field of the invention The invention concerns a fuel supply system for an internal combustion engine, as defined in claim 1. The invention also concerns a power generating unit comprising a piston engine and a fuel supply system, and a power plant comprising a power generating unit. The invention further concerns a method of performing a functionality test of a leakage space of a fuel supply system of a power generating unit. Background of the invention There is an increasing need for large internal combustion engines, such as ship and power plant engines, that can be operated using other types of fuel than conventional liquid fuels, such as light fuel oil or heavy fuel oil. Alternative fuels can be either liquid fuels, such as methanol or ammonia, or gaseous fuels, such as natural gas or hydrogen. The use of alternative fuels helps reducing carbon dioxide and other emissions of the engines. However, the use of alternative fuels also poses many challenges. For instance, leakages of gaseous fuels pose a much more serious safety risk than leakages of liquid fuels with high flash point. Also, some fuels, such as methanol, can be more toxic than conventional fuels, such as light fuel oil. In many cases, the use of alternative fuels causes a need for extra safety measures. A common safety measure to address both the risk of fires and poisoning is to use double-walled pipes for conveying fuel. A double-walled pipe comprises an inner pipe for conveying the fuel and an outer pipe arranged coaxially around the inner pipe to form an annular leakage space between the two pipes. The leakage space collects the fuel possibly leaking from the inner pipes and allows both detecting leakages and conveying the leaking fuel to a safe place, such as a tank or outdoors. In case of gaseous fuels, the leakage space can be an open space that is vented outdoors. A problem related to open leakage spaces is that detection of small leakages is difficult and typically requires an expensive gas detector. A major problem with gas detectors is that the detectors are very sensitive to all sorts of leaks. The detectors sense even so called fugitive leaks, which are minor and non-dangerous leaks. Thus, due to their sensitive nature, the use of gas detectors in fuel supply systems may result in increase of false shutdowns as the detectors detect fugitive leaks and report the leaks to the engine control system, eventually causing the shutdown of the fuel supply system and engine. A further problem with gas detectors is that they do not allow testing the condition of the outer pipe. Another problem encountered with prior outer pipe leakage detection systems is that they typically include various external components, which would maybe not otherwise be associated with the engine. Such components may include for example moving parts such as outlet/inlet valves or gas detectors. The additional parts increase both the system complexity of the fuel supply system and the risk of system failure in case of component malfunctioning or failure. The system complexity is particularly cumbersome when a) the engine is operated in places where repair or maintenance services are elusively available, or b) the engine is operated in such a manner that unexpected fuel supply system failures result in significant loss of revenue. Such places may be remote locations such as jungles, islands or places with underdeveloped infrastructure. Further example of engine operation is when engine is used for electricity generation and utilized in a peaking power plant that is operated during peak electricity demand hours. In a peaking power plant, it is important that all the sub-systems of the power plant remain functional even in a standby mode to allow quick starting of the engines when needed. Frequent starts and varying loads and operating temperatures of peaking power plants cause extra challenges for leak monitoring of fuel supply systems. Summary of the invention An object of the present invention is to provide an improved fuel supply system for an internal combustion engine. Other objects of the invention are to provide an improved power generating unit and power plant. A still further object is to provide an improved method of performing a functionality test of a leakage space of a fuel supply system. The fuel supply system according to the invention comprises a double-walled fuel supply line having an inner pipe for conveying pressurized fuel and an outer pipe arranged around the inner pipe such that an annular leakage space is formed between the inner pipe and the outer pipe, the leakage space being open to the outside of the leakage space for continuous venting of the leakage space, wherein the leakage space is connected to the outside via flow restriction means, and the fuel supply system comprises means for