EP4709979A1 - Method of operating an internal combustion engine, internal combustion engine, fuel supply system for an internal combustion engine and leak unit for a fuel supply system - Google Patents

Method of operating an internal combustion engine, internal combustion engine, fuel supply system for an internal combustion engine and leak unit for a fuel supply system

Info

Publication number
EP4709979A1
EP4709979A1 EP23724003.1A EP23724003A EP4709979A1 EP 4709979 A1 EP4709979 A1 EP 4709979A1 EP 23724003 A EP23724003 A EP 23724003A EP 4709979 A1 EP4709979 A1 EP 4709979A1
Authority
EP
European Patent Office
Prior art keywords
leakage
fuel
leakage space
space
fuel supply
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23724003.1A
Other languages
German (de)
French (fr)
Inventor
Janne PELTTARI
Mathias BJÖRKLUND
Ilari HYÖTY
Oscar SUNNGREN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wartsila Finland Oy
Original Assignee
Wartsila Finland Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wartsila Finland Oy filed Critical Wartsila Finland Oy
Publication of EP4709979A1 publication Critical patent/EP4709979A1/en
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/0011—Constructional details; Manufacturing or assembly of elements of fuel systems; Materials therefor
    • F02M37/0017—Constructional details; Manufacturing or assembly of elements of fuel systems; Materials therefor related to fuel pipes or their connections, e.g. joints or sealings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/0047—Layout or arrangement of systems for feeding fuel
    • F02M37/0064—Layout or arrangement of systems for feeding fuel for engines being fed with multiple fuels or fuels having special properties, e.g. bio-fuels; varying the fuel composition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F02M55/002—Arrangement of leakage or drain conduits in or from injectors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
    • F02M65/006—Measuring or detecting fuel leakage of fuel injection apparatus
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

The method of operating an internal combustion engine (1) having a fuel supply system comprising a double-walled fuel line (2) for supplying fuel to the engine (1) comprises the steps of filling an annular leakage space (5) formed between an inner pipe (3) and an outer pipe (4) of the fuel line (2) with inert gas to create an inert atmosphere within said leakage space (5) (101), maintaining the inert atmosphere in said leakage space (5) while the engine (1) is operated using said first fuel that is conveyed in said double-walled fuel line (2), wherein the pressure of the inert atmosphere is kept within a first pressure range having a lower limit and an upper limit (102), and monitoring possible leakages of said first fuel into said leakage space (5) (103).

Description

Method of operating an internal combustion engine, internal combustion engine, fuel supply system for an internal combustion engine and leak unit for a fuel supply system
Technical field of the invention
The present invention concerns a method of operating an internal combustion engine, as defined in claim 1 . The invention also concerns an internal combustion engine, a fuel supply system for an internal combustion engine and a leak unit for a fuel supply system, as defined in other independent claims.
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 a leakage, the inner pipe and the leakage space can be purged using inert gas, such as nitrogen.
The use of double-walled pipes improves the safety of the engines using alternative fuels, but in some applications there is a need for even further safety improvements. Summary of the invention
An object of the invention is to provide an improved method for operating an internal combustion engine having a fuel supply system comprising a doublewalled fuel line for supplying fuel to the engine, the fuel line comprising an inner pipe configured to convey a first, liquid 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. Another object of the invention is to provide an improved internal combustion engine. A further object of the invention is to provide an improved fuel injection system. A still further object of the invention is to provide a leak unit for a fuel supply system.
The method according to the invention comprises the steps of filling the leakage space with inert gas to create an inert atmosphere within said leakage space, maintaining the inert atmosphere in said leakage space while the engine is operated using said first fuel that is conveyed in said double-walled fuel line, wherein the pressure of the inert atmosphere is kept within a first pressure range having a lower limit and an upper limit, and monitoring possible leakages of said first fuel into said leakage space.
The fuel supply system according to the invention comprises a double-walled fuel line for supplying fuel to the engine, the fuel line comprising an inner pipe configured to convey a first, liquid 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 fuel supply system comprising leak detection means for detecting a leakage of the first fuel into said leakage space, means for supplying inert gas into said leakage space when a leakage into the leakage space is detected to purge said leakage space, and means for supplying inert gas into said leakage space for maintaining an inert atmosphere within said leakage space when the engine is operated using said first fuel.
The engine according to the invention is configured to be operated according to the method defined above.
By maintaining an inert atmosphere in the leakage space, the engine can be operated in a safe manner, as small leakages into the leakage space do not create a flammable mixture. By monitoring possible leakages into the leakage space, corrective measures, such as shutting down of the engine or switching to use another fuel can be taken in case a leakage is detected.
According to an embodiment of the invention, the lower limit of said first pressure range is 50-300 kPa and the upper limit is 50-300 kPa higher than the lower limit. By having a small overpressure in the leakage space, gas tightness of the leakage space can be monitored and leakages of inert gas can be detected. A sufficient difference between the lower limit and the upper limit allows that the supply of the inert gas into the leakage space does not need to be continuous but inert gas can be supplied into the leakage space at predetermined intervals or according to the need. A relatively low upper limit allows using a higher pressure to purge the leakage space when needed.
According to an embodiment of the invention, in predetermined conditions, such as in case a leakage is detected, the leakage space is purged by introducing inert gas into the leakage space at a pressure that is higher than the upper limit of the first pressure range. The purging of the leakage space ensures safe operation of the engine in case of fuel leakages.
According to an embodiment of the invention, the pressure used for purging the leakage space is at least 200 kPa higher than the upper limit of the first pressure range. A sufficiently high pressure ensures effective purging of the leakage space.
According to an embodiment of the invention, the leakage space is divided into at least two separate portions and leakages into the leakage space are monitored to allow determining into which portion of the leakage space fuel is leaking. The leaking part of the fuel line can thus be found quickly.
According to an embodiment of the invention, leakages into the leakage space are monitored by monitoring the pressure of the leakage space. Leakages can be monitored by means of one or more pressure sensors. A pressure rise in the leakage space can indicate a fuel leakage into the leakage space.
According to an embodiment of the invention, leakages into the leakage space are monitored by means of at least one level sensor that is configured to detect the presence of liquid in a leak detection space that is in fluid communication with the leakage space. By means of level sensors, even small leakages can be detected. According to an embodiment of the invention, in case a leakage into the leakage space is detected, an alarm is triggered. An alarm allows an operator of the engine to take necessary corrective measures. Alternatively, or in addition, the engine can be switched to use another fuel or shut down.
According to an embodiment of the invention, in case a leakage into the leakage space is detected, the engine is switched to use another fuel or the engine is shut down. The switch to use another fuel or shutting down of the engine ensures safety. The corrective measures can depend on the amount of leaking fuel. For instance, an alarm can be triggered in case of small leakages, whereas in case of a larger amount of leaking fuel, the engine can be switched to use another fuel or shut down.
According to an embodiment of the invention, in case the pressure of the leakage space drops below a predetermined threshold, an alarm is triggered. Dropping of the pressure of the leakage space can indicate leakage of the inert gas.
According to an embodiment of the invention, the leakage space is refilled with the inert gas at predetermined intervals and/or in case the pressure of the leakage space drops below a predetermined threshold. To maintain the pressure in the leakage space at a correct level, inert gas can be supplied into the leakage space at predetermined intervals or when needed.
According to an embodiment of the invention, the duration of the refilling and/or the amount of inert gas introduced into the leakage space is monitored, and in case the duration of the refilling is longer than a predetermined threshold or the amount of inert gas introduced into the leakage space exceeds a predetermined threshold, an alarm is triggered and/or the engine is switched to use another fuel or shut down. If the filling of the leakage space takes too long or the amount of inert gas is greater than expected, it may be an indication of a leakage of the inert gas.
According to an embodiment of the invention, the first fuel is methanol. Because of the toxicity of methanol, the present invention is particularly useful when the engine is operated using methanol. However, the method could be applied also in engines using other toxic and/or highly flammable liquid fuels.
According to an embodiment of the invention, the inert gas is nitrogen. Nitrogen is an inexpensive inert gas, but also some other inert gas could be used. According to an embodiment of the invention, the fuel supply system comprises at least one pressure sensor for monitoring pressure in said leakage space. A pressure sensor can detect leakages anywhere within a section forming a continuous volume and can thus be positioned more freely than other types of sensors.
According to an embodiment of the invention, the fuel supply system comprises at least one level sensor for detecting leakage of liquid fuel into said leakage space. A level sensor allows detecting even smaller leakages, which are difficult to detect with a pressure sensor.
According to an embodiment of the invention, the means for supplying inert gas into said leakage space when a leakage into the leakage space is detected to purge said leakage space comprise at least one controllable purging valve for controlling flow of inert gas from an inert gas source into the leakage space. If the leakage space comprises separate portions, the fuel supply system can comprise a separate purging valve for each separate portion.
According to an embodiment of the invention, the means for supplying inert gas into said leakage space for maintaining an inert atmosphere within said leakage space when the engine is operated using said first fuel comprise at least one controllable filling valve for controlling flow of inert gas from an inert gas source into the leakage space. If the leakage space comprises separate portions, the fuel supply system can comprise a separate filling valve for each separate portion.
According to an embodiment of the invention, the means for supplying inert gas into said leakage space for maintaining an inert atmosphere within said leakage space when the engine is operated using said first fuel comprise at least one pressure reduction valve for reducing the pressure of the inert gas. The pressure reduction valve allows supplying the inert gas at a lower pressure when the inert gas is used for maintaining the inert atmosphere within the leakage space.
According to an embodiment of the invention, said leakage space is divided into at least two separate portions such that leakage into one of the portions can be detected independently of the other portions. That allows determining the location of a leakage. According to an embodiment of the invention, each separate portion of the leakage space is provided with at least one level sensor and/or pressure sensor for detecting leakage into said portion. This allows locating a leakage.
According to an embodiment of the invention, the fuel supply system comprises a leak unit comprising leak detection means for detecting leakage into the leakage space, and said fuel line comprises at least a first fuel supply portion extending from a fuel pump to said leak unit, a second fuel supply portion extending from said leak unit to an engine, a first overflow portion extending from the engine to said leak unit, and a second overflow portion extending from said leak unit downstream, said leak unit dividing the leakage space into said at least two separate portions. The leak unit allows arranging different functionalities of the fuel supply system into a single module.
The leak unit according to the invention comprises leak detection means for detecting leakage into the leakage space, a fuel supply channel having a fuel inlet connectable to the inner pipe of the first fuel supply portion and a fuel outlet connectable to the inner pipe of the second fuel supply portion, an overflow channel having a fuel inlet connectable to the inner pipe of the first overflow portion and a fuel outlet connectable to the inner pipe of the second overflow portion, a first leakage line having an inlet connectable to a leakage space portion of the first fuel supply portion and an outlet connected to the overflow channel, a first check valve arranged in the first leakage line for preventing flow from the overflow channel towards the inlet of the first leakage line, a second leakage line having an inlet connectable to a leakage space portion of the second fuel supply portion and an outlet connected to the overflow channel, and a second check valve arranged in the second leakage line for preventing flow from the overflow channel towards the inlet of the second leakage line.
The leak unit allows monitoring leakages in different parts of the fuel supply system and collecting possibly leaking fuel.
According to an embodiment of the invention, the leak unit comprises a third check valve arranged in the overflow channel for preventing flow towards the inlet of the overflow channel. The third check valve thus prevents backflow of fuel to the engine. According to an embodiment of the invention, the leak unit comprises a first inert gas channel having an inlet that is connectable to an inert gas source and an outlet connectable to the leakage space portion of the first overflow portion. This allows filling and purging of said leakage space portion via the leak unit.
According to an embodiment of the invention, the leak unit comprises a second inert gas channel having an inlet that is connectable to an inert gas source and an outlet connectable to a leakage space portion of the second overflow portion. Also the leakage space portion of the second overflow portion can thus be filled and purged via the leak unit.
According to an embodiment of the invention, the leak unit comprises at least one leak detection space arranged in fluid communication with the leakage space, a level sensor arranged to detect presence of liquid in said at least one leak detection space, and an outlet for draining the leak detection space. The leak unit can thus be used for both detecting leakages and for discharging leaked fuel.
Brief description of the drawings
Embodiments of the invention are described below in more detail with reference to the accompanying drawings, in which
Fig. 1 shows schematically a fuel supply system according to an embodiment of the invention,
Fig. 2 shows schematically a leak unit according to an embodiment of the invention, and
Fig. 3 shows as a flowchart the method according to the invention.
Detailed description of embodiments of the invention
Figure 1 shows schematically a fuel supply system according to an embodiment of the invention. The fuel supply system supplies liquid fuel to an internal combustion engine 1 . The engine 1 is a piston engine. The engine 1 is a large piston engine, such as a main or an auxiliary engine of a ship or a power plant engine. The cylinder diameter of the engine is at least 150 mm and/or the rated power of the engine is at least 500 kW. The fuel supply system of figure 1 supplies to the engine 1 a first, liquid fuel. The first fuel can be, for instance, methanol. However, the first fuel could also be some other fuel. The first fuel can be, in particular, highly toxic and/or highly flammable, thus requiring specific protective measures for preventing the persons operating the engine 1 from being exposed to the fuel and/or for reducing the risk of fires.
The engine 1 can be provided with two or more separate or partly separate fuel supply systems. For instance, the engine 1 can be operable using a second fuel and the engine 1 could be provided with a separate fuel supply system for supplying the second fuel to the engine 1 . The second fuel could be a liquid fuel, such as light fuel oil, or a gaseous fuel, such as natural gas. The engine 1 could also be operable using mixtures of different fuels or using one fuel as a main fuel and another fuel as a pilot fuel for igniting the main fuel.
The fuel supply system comprises a double-walled fuel line 2 for supplying fuel to the engine 1 . The fuel line 2 comprises an inner pipe 3 that is configured to convey the first fuel and an outer pipe 4 arranged around the inner pipe 3 such that an annular leakage space 5 is formed between the inner pipe 3 and the outer pipe 4. The annular leakage space 5 does not need to be continuous but it can be divided into two or more sections. The fuel supply system comprises at least one fuel pump 19 for pressurizing the first fuel.
The fuel supply system further comprises leak detection means 6, 7, 8, 9, 14, 15, 16 for detecting a leakage of the first fuel into the leakage space 5, means 33, 43, 53 for supplying inert gas into the leakage space 5 when a leakage into the leakage space 5 is detected to purge the leakage space 5, and means 31 , 32, 41 , 42, 51 , 52 for supplying inert gas into the leakage space 5 for maintaining an inert atmosphere within the leakage space 5 when the engine 1 is operated using the first fuel.
In the fuel supply system according to the invention, inert gas is thus used for two purposes: during operation of the engine 1 using the first fuel, the leakage space 5 is kept filled with the inert gas. The inert atmosphere in the leakage space 5 effectively reduces the risk of fires if fuel leaks from the inner pipe 3 into the leakage space 5. In case of a leakage, the inert gas can be used for purging the leakage space 5 to remove the leaked fuel from the leakage space 5. The inert gas can be, for instance, nitrogen. The leak detection means can comprise one or more pressure sensors 14, 15, 16 and/or one or more level sensors 6, 7, 8, 9. The level sensors 6, 7, 8, 9 can detect even small leakages of liquid fuel, but need to be positioned such that the leaking fuel reaches at least one of the level sensors. Pressure sensors 14, 15, 16 can be positioned more freely, but do not necessarily detect as small leakages as the level sensors 6, 7, 8, 9. On the other hand, the pressure sensors 14, 15, 16 can also be configured to detect leakages from the leakage space 5.
The leakage space 5 can be divided into two or more separate portions 5A, 5B, 5C, 5D such that leakage into one of the portions 5A, 5B, 5C, 5D can be detected independently of the other portions. This allows detecting where the fuel supply system is leaking. Also, in case of a leakage, it is not necessary to purge the whole leakage space 5 but it is sufficient to purge the affected portions of the leakage space 5.
In the embodiment of figure 1 , different functionalities of the fuel supply system are arranged in a leak unit 20. This provides a convenient way for filling the leakage space 5 with inert gas, monitoring leakages and purging the leakage space 5. However, the leak unit 20 is not necessary, but the fuel supply system could be implemented without the leak unit 20.
The leak unit 20 comprises the leak detection means 6, 7, 8, 9, 14, 15, 16 for detecting a leakage into the leakage space 5. The fuel line 2 comprises a first fuel supply portion 2A extending from the fuel pump 19 to the leak unit 20, a second fuel supply portion 2B extending from the leak unit 20 to the engine 1 , a first overflow portion 2C extending from the engine 1 to the leak unit 20, and a second overflow portion 2D extending from the leak unit 20 downstream. The leak unit 20 divides the leakage space 5 into the two or more separate portions 5A, 5B, 5C, 5D.
The first fuel is supplied via the first and second fuel supply portions 2A, 2B to the engine 1 . Excess fuel from the engine 1 flows via the overflow portions 2C, 2D to an overflow tank.
Figure 2 shows details of a leak unit 20 according to an embodiment of the invention. The leak unit 20 comprises a fuel supply channel 21 having a fuel inlet 21A connectable to the inner pipe 3A of the first fuel supply portion 2A and a fuel outlet 21 B connectable to the inner pipe 3B of the second fuel supply portion 2B, an overflow channel 22 having a fuel inlet 22A connectable to the inner pipe 3C of the first overflow portion 2C and a fuel outlet 22B connectable to the inner pipe 3C of the second overflow portion 2C. The leak unit 20 further comprises a first leakage line 23 having an inlet 23A connectable to a leakage space portion 5A of the first fuel supply portion 2A and an outlet 23B connected to the overflow channel 22, a first check valve 24 arranged in the first leakage line 23 for preventing flow from the overflow channel 22 towards the inlet 23A of the first leakage line 23, a second leakage line 25 having an inlet 25A connectable to a leakage space portion 5B of the second fuel supply portion 2B and an outlet 25B connected to the overflow channel 22, and a second check valve 26 arranged in the second leakage line 25 for preventing flow from the overflow channel 22 towards the inlet 25A of the second leakage line 25. In the embodiment of the figures, the leak unit 20 further comprises a third check valve 27 arranged in the overflow channel 22 for preventing flow towards the inlet 22A of the overflow channel 22.
In the embodiment of the figures, the leakage space 5 thus comprises four portions 5A, 5B, 5C, 5D. However, the leakage space portions 5B, 5C of the second fuel supply portion 2B and the first overflow portion 2C are in fluid communication with each other and thus not completely separated from each other. The fuel supply system is provided with a first pressure sensor 14, second pressure sensor 15 and third pressure sensor 16, which function as leak detection means. The first pressure sensor 14 is configured to monitor pressure in the leakage space portion 5A of the first fuel supply portion 2A, the second pressure sensor 15 is configured to monitor pressure in the leakage space portion 5D of the second overflow portion 2D, and the third pressure sensor 16 is configured to monitor pressure in the leakage space portions 5B, 5C of the second fuel supply portion 2B and the first overflow portion 2C.
In case of a leakage of the first fuel supply portion 2A, the fuel leaking into the leakage space 5 can be purged via the first leakage line 23 into the overflow channel 22. Similarly, a fuel leakage of the second fuel supply portion 2B can be purged via the second leakage line 25 into the overflow channel 22. The leak unit 20 further comprises leak detection spaces 10, 11 , 12, 13 arranged in fluid communication with each leakage space portion 5A, 5B, 5C, 5D of the leakage space 5 and a level sensor 6, 7, 8, 9 arranged to detect presence of liquid in each of the leak detection spaces 10, 11 , 12, 13. The leak unit 20 is arranged such that it forms the lowermost part of the fuel supply system and the fuel leaking into the leakage space 5 thus flows to the leak unit 20 by gravity.
The leak unit 20 further comprises an outlet 36, 37, 38, 39 and a drain valve 44, 45, 46, 47 for draining each of the leak detection spaces 10, 11 , 12, 13.
The leak unit 20 also comprises a first inert gas channel 28 having an inlet 28A that is connectable to an inert gas source 48 and an outlet 28B connectable to the leakage space portion 5C of the first overflow portion 2C. The leak unit 20 of the figures further comprises a second inert gas channel 29 having an inlet 29A that is connectable to an inert gas source 48 and an outlet 29B connectable to the leakage space portion 5D of the second overflow portion 2D. The inert gas channels 28, 29 allow introducing inert gas into the leakage space 5 for maintaining the inert atmosphere in the leakage space 5 and for purging the leakage space 5. In the embodiment of the figures, the leakage space portion 5A of the first fuel supply portion 2A is not filled via the leak unit 20.
For filling the leakage space 5 with the inert gas, the leakage space 5 is connected to the inert gas source 48. The inert gas can be stored in a tank at a pressure that is at least as high as the pressure needed for purging the leakage space 5. Alternatively, a pump can be arranged between the inert gas tank and the leakage space 5 to raise the pressure of the inert gas. The pressure used for purging the leakage space 5 can be, for instance, in the range of 600-1200 kPa.
Each separate portion of the leakage space 5 is connected to the inert gas source 48 via a filling valve 31 , 41 , 51 . The filling valves are controllable valves. In the embodiment of the figures, the fuel supply system comprises a first filling valve 31 for controlling the supply of inert gas into the leakage space portion 5A of the first fuel supply portion 2A, a second filling valve 41 for controlling the supply of inert gas into the leakage space portion 5D of the second overflow portion 2D, and a third filling valve 51 for controlling the supply of inert gas into the leakage space portions 5B, 5C of the second fuel supply portion 2B and the first overflow portion 2C. Each inert gas line supplying inert gas into the leakage space 5 is further provided with a pressure reduction valve 32, 42, 52 for lowering the pressure of the inert gas to the desired pressure level. The pressure of the inert gas supplied into the leakage space 5 for maintaining the inert atmosphere could be, for instance, in the range of 150-400 kPa.
For purging the leakage space 5, the fuel supply system is provided with a purging valve 33, 43, 53 for each separate portion of the leakage space 5 for supplying the inert gas into the respective portion 5A, 5B, 5C, 5D at a higher pressure. In the embodiment of the figures, the fuel supply system thus comprises a first purging valve 33, a second purging valve 43, and a third purging valve 53. Via the purging valves 33, 43, 53, the inert gas can be supplied into the leakage space 5 at a higher pressure than via the filling valves 31 , 41 , 51 .
The same valves could be used both as the purging valves and the filling valves if the pressure of the inert gas can be regulated according to the need.
Figure 3 shows as a flowchart the method according to the invention for operating an internal combustion engine 1 . The fuel supply system of the engine 1 can be as in the embodiment of figure 1 . However, the fuel supply system does not need to comprise all the features of figure 1 and/or the fuel supply system can also comprise features not shown in figure 1 .
In a first step 101 of the method, the leakage space 5 is filled with inert gas to create an inert atmosphere within the leakage space 5. If the leakage space 5 is divided into separate portions 5A, 5B, 5C, 5D, each portion can be filled with the inert gas. In a second step 102 of the method, the inert atmosphere is maintained in the leakage space 5 while the engine 1 is operated using the first fuel that is conveyed in the double-walled fuel line 2, wherein the pressure of the inert atmosphere is kept within a first pressure range having a lower limit and an upper limit. In a third step 103 of the method, possible leakages of the first fuel into the leakage space 5 are monitored. If the leakage space 5 is divided into separate portions 5A, 5B, 5C, 5D, possible leakages into each of the portions can be monitored separately.
The lower limit of the first pressure range can be, for instance, 50-300 kPa and the upper limit can be, for instance, 50-300 kPa higher than the lower limit. In predetermined conditions, such as in case a leakage is detected, the leakage space 5 can be purged by introducing inert gas into the leakage space 5 at a pressure that is higher than the upper limit of the first pressure range. The pressure used for purging the leakage space 5 can be configured to be, for instance, at least 200 kPa higher than the upper limit of the first pressure range.
Leakages into the leakage space 5 can be monitored by monitoring the pressure of the leakage space 5. In addition, or instead of monitoring leakages by the pressure monitoring, leakages into the leakage space 5 can be monitored by means of at least one level sensor 6, 7, 8, 9 that is configured to detect the presence of liquid in a leak detection space 10, 11 , 12, 13 that is in fluid communication with the leakage space 5.
In case a leakage into the leakage space 5 is detected, an alarm can be triggered. Alternatively, or in addition, the engine 1 can be switched to use another fuel or the engine 1 can be shut down. For instance, in case the first fuel is methanol, the engine 1 could be switched to use light fuel oil.
The pressure monitoring of the leakage space 5 can also be used for determining whether a sufficient pressure of the inert atmosphere is maintained in the leakage space 5. For instance, if the pressure of the leakage space 5 drops within a predetermined period of time below a predetermined threshold, an alarm can be triggered.
To maintain the inert atmosphere in the leakage space 5, the leakage space 5 can be refilled with the inert gas at predetermined intervals. Alternatively, or in addition, the leakage space 5 can be refilled with the inert gas in case the pressure of the leakage space 5 drops below a predetermined threshold after a predetermined period of time has lapsed.
When the leakage space 5 is refilled, the duration of the refilling and/or the amount of inert gas introduced into the leakage space 5 can be monitored, and in case the duration of the refilling is longer than a predetermined threshold or the amount of inert gas introduced into the leakage space 5 exceeds a predetermined threshold, an alarm can be triggered and/or the engine 1 can be switched to use another fuel or shut down. By monitoring the duration of the filling or the amount of inert gas, it can be ensured that the leakage space 5 is not leaking and safe inert atmosphere is maintained within the leakage space
5.

Claims

Claims:
1. A method of operating an internal combustion engine (1 ) having a fuel supply system comprising a double-walled fuel line (2) for supplying fuel to the engine (1 ), the fuel line (2) comprising an inner pipe (3) configured to convey a first, liquid fuel and an outer pipe (4) arranged around the inner pipe (3) such that an annular leakage space (5) is formed between the inner pipe (3) and the outer pipe (4), the method comprising the steps of filling the leakage space (5) with inert gas to create an inert atmosphere within said leakage space (5) (101 ), maintaining the inert atmosphere in said leakage space (5) while the engine (1 ) is operated using said first fuel that is conveyed in said double-walled fuel line (2), wherein the pressure of the inert atmosphere is kept within a first pressure range having a lower limit and an upper limit (102), and monitoring possible leakages of said first fuel into said leakage space (5) (103).
2. A method according to claim 1 , wherein the lower limit of said first pressure range is 50-300 kPa and the upper limit is 50-300 kPa higher than the lower limit.
3. A method according to claim 1 or 2, wherein in predetermined conditions, such as in case a leakage is detected, the leakage space (5) is purged by introducing inert gas into the leakage space (5) at a pressure that is higher than the upper limit of the first pressure range.
4. A method according to claim 3, wherein the pressure used for purging the leakage space (5) is at least 200 kPa higher than the upper limit of the first pressure range.
5. A method according to any of the preceding claims, wherein the leakage space (5) is divided into at least two separate portions (5A, 5B, 5C, 5D) and leakages into the leakage space (5) are monitored to allow determining into which portion (5A, 5B, 5C, 5D) of the leakage space (5) fuel is leaking.
6. A method according to any of the preceding claims, wherein leakages into the leakage space (5) are monitored by monitoring the pressure of the leakage space (5).
7. A method according to any of the preceding claims, wherein leakages into the leakage space (5) are monitored by means of at least one level sensor (6, 7, 8, 9) that is configured to detect the presence of liquid in a leak detection space (10, 11 , 12, 13) that is in fluid communication with the leakage space (5).
8. A method according to any of the preceding claims, wherein in case a leakage into the leakage space (5) is detected, an alarm is triggered.
9. A method according to any of the preceding claims, wherein in case a leakage into the leakage space (5) is detected, the engine (1 ) is switched to use another fuel or the engine (1 ) is shut down.
10. A method according to any of the preceding claims, wherein in case the pressure of the leakage space (5) drops below a predetermined threshold, an alarm is triggered, the engine (1 ) is switched to use another fuel, or the engine (1 ) is shut down.
11. A method according to any of the preceding claims, wherein the leakage space (5) is refilled with the inert gas at predetermined intervals and/or in case the pressure of the leakage space (5) drops below a predetermined threshold.
12. A method according to claim 11 , wherein the duration of the refilling and/or the amount of inert gas introduced into the leakage space (5) is monitored, and in case the duration of the refilling is longer than a predetermined threshold or the amount of inert gas introduced into the leakage space (5) exceeds a predetermined threshold, an alarm is triggered and/or the engine (1 ) is switched to use another fuel or shut down.
13. A method according to any of the preceding claims, wherein the first fuel is methanol.
14. A method according to any of the preceding claims, wherein the inert gas is nitrogen.
15. An internal combustion engine (1 ) configured to operate according to the method of any of the preceding claims.
16. A fuel supply system for an internal combustion engine (1 ), the fuel supply system comprising a double-walled fuel line (2) for supplying fuel to the engine (1 ), the fuel line (2) comprising an inner pipe (3) configured to convey a first, liquid fuel and an outer pipe (4) arranged around the inner pipe (3) such that an annular leakage space (5) is formed between the inner pipe (3) and the outer pipe (4), the fuel supply system comprising leak detection means (6, 7, 8, 9, 14, 15, 16) for detecting a leakage of the first fuel into said leakage space (5), means (33, 43, 53) for supplying inert gas into said leakage space (5) when a leakage into the leakage space (5) is detected to purge said leakage space (5), and means (31 , 32, 41 , 42, 51 , 52) for supplying inert gas into said leakage space (5) for maintaining an inert atmosphere within said leakage space (5) when the engine (1 ) is operated using said first fuel.
17. A fuel supply system according to claim 16, wherein the fuel supply system comprises at least one pressure sensor (14, 15, 16) for monitoring pressure in said leakage space (5).
18. A fuel supply system according to claim 16 or 17, wherein the fuel supply system comprises at least one level sensor (6, 7, 8, 9) for detecting leakage of liquid fuel into said leakage space (5).
19. A fuel supply system according to any of claims 16-18, wherein the means for supplying inert gas into said leakage space (5) when a leakage into the leakage space (5) is detected to purge said leakage space (5) comprise at least one controllable purging valve (33, 43, 53) for controlling flow of inert gas from an inert gas source (48) into the leakage space (5).
20. A fuel supply system according to any of claims 16-19, wherein the means (31 , 32, 41 , 42, 51 , 52) for supplying inert gas into said leakage space (5) for maintaining an inert atmosphere within said leakage space (5) when the engine (1 ) is operated using said first fuel comprise at least one controllable filling valve (31 , 41 , 51 ) for controlling flow of inert gas from an inert gas source (48) into the leakage space (5).
21 . A fuel supply system according to claim 20, wherein the means (31 , 32, 41 , 42, 51 , 52) for supplying inert gas into said leakage space (5) for maintaining an inert atmosphere within said leakage space (5) when the engine (1 ) is operated using said first fuel comprise at least one pressure reduction valve (32, 42, 52) for reducing the pressure of the inert gas.
22. A fuel supply system according to any of claims 16-21 , wherein said leakage space (5) is divided into at least two separate portions (5A, 5B, 5C, 5D) such that leakage into one of the portions (5A, 5B, 5C, 5D) can be detected independently of the other portions.
23. A fuel supply system according to claim 22, wherein each separate portion (5A, 5B, 5C, 5D) of the leakage space (5) is provided with at least one level sensor (6, 7, 8, 9) and/or pressure sensor (14, 15, 16) for detecting leakage into said portion (5A, 5B, 5C, 5D).
24. A fuel supply system according to claim 22 or 23, wherein the fuel supply system comprises a leak unit (20) comprising leak detection means (6, 7, 8, 9, 14, 15, 16) for detecting leakage into the leakage space (5), and said fuel line (2) comprises at least a first fuel supply portion (2A) extending from a fuel pump (19) to said leak unit (20), a second fuel supply portion (2B) extending from said leak unit (20) to an engine (1 ), a first overflow portion (2C) extending from the engine (1 ) to said leak unit (20), and a second overflow portion (2D) extending from said leak unit (20) downstream, said leak unit (20) dividing the leakage space (5) into said at least two separate portions (5A, 5B, 5C, 5D).
25. A leak unit (20) for a fuel supply system according to claim 24, the leak unit (20) comprising leak detection means (6, 7, 8, 9, 14, 15, 16) for detecting leakage into the leakage space (5), a fuel supply channel (21 ) having a fuel inlet (21 A) connectable to the inner pipe (3A) of the first fuel supply portion (2A) and a fuel outlet (21 B) connectable to the inner pipe (3B) of the second fuel supply portion (2B), an overflow channel (22) having a fuel inlet (22A) connectable to the inner pipe (3C) of the first overflow portion (2C) and a fuel outlet (22B) connectable to the inner pipe (3C) of the second overflow portion (2C), a first leakage line (23) having an inlet (23A) connectable to a leakage space portion (5A) of the first fuel supply portion (2A) and an outlet (23B) connected to the overflow channel (22), a first check valve (24) arranged in the first leakage line (23) for preventing flow from the overflow channel (22) towards the inlet (23A) of the first leakage line (23), a second leakage line (25) having an inlet (25A) connectable to a leakage space portion (5B) of the second fuel supply portion (2B) and an outlet (25B) connected to the overflow channel (22), and a second check valve (26) arranged in the second leakage line (25) for preventing flow from the overflow channel (22) towards the inlet (25A) of the second leakage line (25).
26. A leak unit (20) according to claim 25, wherein the leak unit (20) comprises a third check valve (27) arranged in the overflow channel (22) for preventing flow towards the inlet (22A) of the overflow channel (22).
27. A leak unit (20) according to claim 25 or 26, wherein the leak unit (20) comprises a first inert gas channel (28) having an inlet (28A) that is connectable to an inert gas source (48) and an outlet (28B) connectable to the leakage space portion (5C) of the first overflow portion (2C).
28. A leak unit (20) according to any of claims 25-27, wherein the leak unit (20) comprises a second inert gas channel (29) having an inlet (29A) that is connectable to an inert gas source (48) and an outlet (29B) connectable to a leakage space portion (5D) of the second overflow portion (2D).
29. A leak unit (20) according to any of claims 25-28, wherein the leak unit (20) comprises at least one leak detection space (10, 11 , 12, 13) arranged in fluid communication with the leakage space (5), a level sensor (6, 7, 8, 9) arranged to detect presence of liquid in said at least one leak detection space (10, 11 , 12, 13), and an outlet (36, 37, 38, 39) for draining the leak detection space (10, 11 , 12, 13).
EP23724003.1A 2023-05-08 2023-05-08 Method of operating an internal combustion engine, internal combustion engine, fuel supply system for an internal combustion engine and leak unit for a fuel supply system Pending EP4709979A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/FI2023/050250 WO2024231592A1 (en) 2023-05-08 2023-05-08 Method of operating an internal combustion engine, internal combustion engine, fuel supply system for an internal combustion engine and leak unit for a fuel supply system

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EP4709979A1 true EP4709979A1 (en) 2026-03-18

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EP23724003.1A Pending EP4709979A1 (en) 2023-05-08 2023-05-08 Method of operating an internal combustion engine, internal combustion engine, fuel supply system for an internal combustion engine and leak unit for a fuel supply system

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EP (1) EP4709979A1 (en)
KR (1) KR20250174726A (en)
CN (1) CN121079498A (en)
WO (1) WO2024231592A1 (en)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2011996B1 (en) * 2007-07-04 2012-03-14 Caterpillar Motoren GmbH & Co. KG Fuel system for a combustion engine having local leakage detection
ES2536309T3 (en) * 2011-11-04 2015-05-22 Caterpillar Motoren Gmbh & Co. Kg Double wall fuel supply pipe element
US20150129076A1 (en) * 2015-01-23 2015-05-14 Caterpillar Inc. Fuel supply routing assembly for engine to detect fuel leakage

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WO2024231592A1 (en) 2024-11-14
CN121079498A (en) 2025-12-05

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