JP2022075566A - Compression ignition internal combustion engine operating with ammonia, and modified kit - Google Patents

Abstract

To provide a compression ignition internal combustion engine having at least one operating mode in which main fuel is ammonia.SOLUTION: An engine comprises a cylinder 1 having a reciprocating piston 10 inside and a cylinder cover 22 covering itself, a combustion chamber formed between the reciprocating piston in the cylinder and the cylinder cover, a prechamber 33 that is arranged on the cylinder cover and connected to the combustion chamber so that it can be moved back and forth through an opening, and an ammonia valve 50 with a nozzle provided with a plurality of nozzle holes that open to the prechamber. The ammonia valve has an inlet port connected to a source of pressurized liquid ammonia, and the ammonia valve is configured to inject the liquid ammonia from the source into the prechamber through the nozzle holes.SELECTED DRAWING: Figure 4

Description

The disclosure of the present application relates to a compression ignition internal combustion engine such as a crosshead type large low speed 2-stroke compression ignition internal combustion engine, and relates to a compression ignition internal combustion engine in which at least one of the operation modes is an operation mode in which ammonia is used as a main fuel.

background

Compression ignition Internal combustion engines (diesel engines) have traditionally been driven primarily by hydrocarbon fuels such as fuel oils such as diesel oil and fuel gases such as natural gas or petroleum gas. Combustion of hydrogen fuel is accompanied by the generation of greenhouse gases such as carbon dioxide (CO ₂ ), which can cause air pollution and climate change. Unlike petroleum fuel impurities that produce by-products emissions, the generation of CO ₂ is inevitable for the combustion of hydrocarbons. Fuel energy density and CO ₂ footprint depend on the length of the hydrocarbon chain and the complexity of the hydrocarbon molecule. For this reason, gas hydrocarbon fuels have a smaller footprint than liquid hydrocarbon fuels. However, gas hydrocarbon fuels are more difficult and costly to handle and store. Non-hydrocarbon fuels have been studied to reduce the CO ₂ footprint.

Ammonia is a compound obtained from petroleum, biomass and renewable energy sources (wind, solar, hydro, geothermal). Ammonia produced using renewable energy sources has a virtually zero carbon footprint when burned, or virtually zero emissions of CO ₂ , SOx, particulate matter, and unburned hydrocarbons.

Ammonia has been tested and used on a small scale in spark-ignition internal combustion engines. However, it has not yet been used to operate a compression ignition internal combustion engine.

A turbocharged large two-stroke uniflow scavenging compression internal combustion crosshead engine is typically used as a propulsion system for large vessels or as a prime mover for a power plant. Its size, weight, and output make this type of compressed internal combustion engine far from other combustion engines, placing this type of compressed internal combustion engine in a unique category.

EP266477 discloses the turbocharged large two-stroke uniflow scavenging compression internal combustion engine according to claim 1. In this engine, ammonia is injected into the combustion chamber as fuel and as a reducing agent. Ammonia, along with a reduction catalyst located downstream of the turbocharger turbine, assists in the process of reducing NOx emissions.

An object is to provide a compression ignition internal combustion engine having at least one mode of operation in which the main fuel is ammonia.

The above-mentioned objectives and other objectives are achieved by the characteristics described in the independent claims. More specific implementations will be clarified from the dependent claims, detailed description of the invention, and drawings.

According to the first concept, a large two-stroke turbocharged uniflow scavenging compression ignition internal combustion engine is provided as follows. The engine is configured to operate on ammonia as the main fuel or the sole fuel in at least one mode of operation.
With at least one cylinder provided in the cylinder liner having a reciprocating piston inside, a cylinder cover covering itself, and a cylinder liner where the scavenging port is located.
A combustion chamber formed between the reciprocating piston in the cylinder and the cylinder cover,
The exhaust valve arranged in the center of the cylinder cover and
With at least one prechamber located on the cylinder cover and connected to the combustion chamber to allow fluid to flow through the openings.
An ammonia valve having a nozzle provided with a plurality of nozzle holes opening to at least one prechamber,
Equipped with
The ammonia valve has an inlet port connected to a source of pressurized ammonia.
The ammonia valve is configured to inject liquid ammonia from the source into the prechamber through the nozzle holes.

There are some technical challenges in using ammonia as a fuel. One of the challenges is low output density compared to typical hydrocarbon fuels. This leads to a very large amount of fuel having to be injected, thus leading to a large flow rate. Such a large flow rate can result in flame digestion. That is, even if ignition occurs very early in the injection event, the subsequent large flow rate and the accompanying high speed fuel jet will extinguish (blow out) the flame. Another issue is that ammonia is less ignitable (flammable) than liquid hydrocarbon fuels. A further challenge is the large evaporative cooling of ammonia, which cools the fuel during injection. Therefore, a lot of ignition energy is required. High temperature in the fuel region is a prerequisite for stable combustion due to strong evaporative cooling. These technical challenges have strongly prevented the use of ammonia as the main fuel in compression ignition engines.

The inventor of the present application injects ammonia into the prechamber connected to the combustion chamber at the opening through the nozzle of the ammonia valve, which causes a significant deceleration of the fuel before the fuel enters the combustion chamber through the opening, and the prechamber is preheated. I realized that it could act as a chamber. Therefore, the fuel rate decreases when entering the combustion chamber through the opening, and the fuel temperature rises when entering the combustion chamber. Thereby, the above-mentioned problems related to the use of ammonia as a fuel in a compression ignition internal combustion engine are solved at least in part.

In one example of the first capture embodiment, the engine comprises an ignition fluid valve associated with at least one prechamber, the ignition fluid valve comprises an ignition fluid nozzle having nozzle holes, and the ignition fluid valve. Is connected to a source of pressurized ignition fluid. As a result, the ignition fluid is mixed with ammonia in the prechamber, and the reliability of ignition of ammonia is improved. By injecting the ignition fluid into the prechamber at high pressure, it is guaranteed that the ignition fluid is well dispersed in the ammonia, and that the mixture of the ignition fluid and the ammonia is already well mixed when it enters the combustion chamber. Will be done.

In one example of the implementation of the first conception, the source of the pressurized ignition fluid is either a source of the pressurized pilot fluid or a source of the pressurized ignition accelerator. The pilot fluid can be, for example, dimethyl ether (GME) or fuel oil. The ignition accelerator can be, for example, hydrogen. The hydrogen may be obtained from an external source or may be produced from ammonia itself using, for example, a catalytic process.

In one example of the implementation of the first conception, the engine injects pilot fluid through the nozzle of the ignition fluid valve and then only ammonia through the nozzle of the ammonia valve, or through the ignition fluid valve. It is configured to inject both the pilot fluid and ammonia through the ammonia valve.

In an example of the implementation of the first conception, the prechamber takes the form of an insert in the cylinder cover. Therefore, if the pre-chamber or the opening between the pre-chamber and the combustion chamber is damaged, the pre-chamber can be easily replaced by simply replacing the insert, and therefore the entire cylinder cover can be repaired and processed. There is no need to do.

In an example of the implementation of the first conception, the prechamber forms a single unit with the ammonia valve, the single unit being an insert placed in the cylinder cover. Therefore, the prechamber and ammonia valve can be attached to the cylinder cover with a single operation.

In an example of the implementation of the first conception, at least a part of the wall separating the prechamber from the combustion chamber forms a protrusion from the cylinder cover to the combustion chamber. By forming a protrusion into the combustion chamber, the walls separating the prechamber are ensured to heat up during the operation of the engine. This ensures that the prechamber becomes hot and that the region of the combustion chamber near the prechamber becomes hot. Therefore, it is ensured that the region where ammonia reaches is high in temperature, and the reliability of combustion is enhanced.

In an example of the implementation of the first conception, the total cross-sectional area of the plurality of nozzle holes is smaller than the cross-sectional area of the opening between the prechamber and the combustion chamber. It is preferably much smaller, more preferably less than half. This allows ammonia to enter the combustion chamber at a much slower rate than when it enters the prechamber.

In an example of the implementation form of the first conception, a plurality of prechambers are arranged around the exhaust valve.

In an example of the implementation of the first conception, the pressurized ammonia source is a pressurized liquid phase ammonia source.

In one example of the implementation of the first conception, the engine is configured to simultaneously inject ammonia and other fuels into the prechamber.

In one example of the implementation of the first capture, the engine comprises a fuel valve having a nozzle with nozzle holes opening in the at least one prechamber, wherein the fuel valve is of another pressurized fuel. It has an inlet port connected to the source and is configured to inject the other fuel from the source into the prechamber through the nozzle holes of the fuel valve.

According to the second perspective, a modified kit for a compression ignition internal combustion engine is provided. This modification kit is a kit for putting the engine into a state in which it is appropriate to operate on ammonia as the main fuel or the sole fuel in at least one mode of operation. Here, the institution is
With at least one cylinder having a reciprocating piston inside and a cylinder cover covering itself,
A combustion chamber formed between the reciprocating piston in the cylinder and the cylinder cover,
The modified kit is equipped with
A prechamber that is attached to the cylinder cover and has an opening for connecting the prechamber to the combustion chamber.
An ammonia valve having a nozzle provided with a plurality of nozzle holes opening to at least one prechamber,
Equipped with
The ammonia valve has an inlet port connected to a source of pressurized liquid ammonia.
The ammonia valve is configured to inject liquid ammonia from the source into the prechamber through the nozzle holes.

These and other perspectives will be further clarified by the examples described below.

Hereinafter, various ways of thinking, embodiments, and implementation examples will be described in detail with reference to the exemplary embodiments shown in the drawings.
It is a figure which shows the overview of the large-sized two-stroke diesel engine which according to an exemplary embodiment as seen from the front direction. It is a figure which shows the overview of the large two-stroke engine of FIG. 1 as seen from the rear direction. It is a schematic representation of the large two-stroke engine of FIG. It is sectional drawing which shows the detailed structure which concerns on the cylinder of the large 2-stroke engine of FIG. It is a schematic representation of the ammonia valve used in the large two-stroke engine of FIG. It is a schematic representation of a fuel valve for ammonia fuel used in the large two-stroke engine of FIG. It is a schematic representation of the ignition liquid valve used in the large two-stroke engine of FIG. FIG. 3 is a schematic cross-sectional view of an ammonia valve and a prechamber forming a single unit mounted on the cylinder cover of the large two-stroke engine of FIG.

Detailed explanation

In the following detailed description, the compression ignition internal combustion engine will be described with reference to the crosshead type large low speed 2-stroke uniflow scavenging turbocharged compression ignition internal combustion engine. Note that in some cases, the compression ignition internal combustion engine may be another type of engine.

1-Fig. 3 depicts a turbocharged large low-speed 2-stroke diesel engine. This engine has a crankshaft 8 and a crosshead 9. FIG. 3 is a schematic representation of a turbocharged large low-speed 2-stroke diesel engine together with its intake system and exhaust system. In an embodiment, the engine has six cylinders 1 in series. A turbocharged large low speed 2-stroke diesel engine typically has 4 to 14 cylinders arranged in series. These cylinders are supported on the cylinder frame 23. The cylinder frame 23 is supported on the engine frame 11. Further, such an engine can be used, for example, as a main engine of a ship or a fixed engine for operating a generator in a power plant. The total output of the engine can be, for example, 1000 kW to 110,000 kW.

The engine in this embodiment is a two-stroke uniflow compression ignition type engine, and each cylinder liner 1 is provided with a scavenging port 18 in a lower region thereof, and an exhaust valve is arranged in the center of the top thereof. The scavenging air is guided to the scavenging port 18 of each cylinder 1 through the scavenging receiver 2. The piston 10 reciprocates between the bottom dead center (BDC) and the top dead center (TDC) in the cylinder liner 1 to compress the scavenging air. Ammonia is injected from the ammonia valve 50. The ammonia valve 50 is arranged on the cylinder cover 22. Combustion occurs following the injection of ammonia, producing exhaust gas. The ammonia valve 50 is configured to inject ammonia. In some embodiments, the engine has an additional fuel valve. Additional fuel valves, not shown, are configured to inject conventional fuels such as fuel oil and heavy oil. In such an embodiment, the engine is a dual engine and comprises a fuel supply system for supplying conventional fuel (not shown).

When the exhaust valve 4 is opened, the exhaust gas flows to the exhaust receiver 3 through the exhaust duct provided in the cylinder 1, and further advances to the turbine 6 of the turbocharger 5 through the first exhaust pipe 19. From there, the exhaust gas flows through the second exhaust pipe 25 to the economizer 20 and is further discharged into the atmosphere from the outlet 21.

The turbine 6 drives the compressor 7 via a shaft. Outside air is supplied to the compressor 9 through the air intake port 12. The compressor 7 sends the compressed scavenging air to the scavenging pipe 13 connected to the scavenging receiver 2. The scavenging pipe 13 passes through an intercooler 14 for cooling the scavenging air.

The cooled scavenging air passes through an auxiliary blower 16 driven by an electric motor 17. The auxiliary blower 16 compresses the scavenging airflow when the compressor 7 of the turbocharger 5 cannot provide sufficient pressure for the scavenging receiver 2, i.e., when the engine is underloaded or partially loaded. If the engine load is high, the turbocharger compressor 7 can supply a fully compressed scavenger so that the auxiliary blower 16 is bypassed by the check valve 15.

The engine is operated on ammonia as the main fuel in at least one mode of operation. Ammonia is supplied to the ammonia valve 50 at a substantially constant pressure and temperature. Ammonia can be supplied to the ammonia valve 50 in liquid or gas phase. The liquid phase ammonia may be aqueous ammonia (ammonia), that is, an aqueous solution of ammonia.

The ammonia fuel system 30 forms part of a source 40 of pressurized liquid phase ammonia. The ammonia fuel system 30 supplies liquid ammonia to the ammonia valve 50 through a supply pipe 31 at a relatively low supply pressure (eg 30-80 bar). In an alternative example, ammonia is supplied to the ammonia valve 50 in the gas phase at a relatively low supply pressure (eg 30-80 bar).

In some embodiments, ammonia is stored in a type C pressure storage tank (not shown) in liquid phase at about 17 bar. Ammonia is a liquid phase at a temperature of 20 ° C. and a pressure higher than 8.6 bar. However, in order to maintain the liquid phase even when the temperature rises, it is preferable to store ammonia at about 17 bar. Existing engines configured to operate on LPGs and other gas fuels stored in the liquid phase will become ammonia combustion engines with relatively minor modifications, i.e., according to embodiments of the invention disclosed herein. Can be remodeled into. For the modification, a slightly modified fuel supply system will be used, but since the same fuel tank can be used, the modification can be made on a relatively small scale.

The ammonia valve 50 has an inlet port connected to the pressurized liquid phase ammonia source 40. In some embodiments, the pressurized liquid phase ammonia source is part of a fuel system 30 configured to supply pressurized liquid phase ammonia to the ammonia valve 50.

Referring to FIG. 4, a cylinder 1 supported on a cylinder frame 23 is shown. A cylinder cover 22 is fastened on the cylinder 1. The piston 10 is also drawn, and the top dead center and bottom dead center are shown by broken lines. A combustion chamber is formed in the cylinder. The combustion chamber is formed between the reciprocating piston 10 and the cylinder cover 22. An exhaust valve 4 is arranged in the center of the cylinder cover 22. On the cylinder cover 22 of each cylinder 1, two or three ammonia valves 50 are arranged (circumferentially) around the central exhaust valve 4.

FIG. 5 illustrates the ammonia valve 50 in more detail. The ammonia valve 50 has a long valve body and a nozzle 51 at the front end of the valve body. The ammonia valve 50 has an ammonia inlet port. The ammonia inlet port is connected to the pressurized liquid phase ammonia source 40. The nozzle 51 is preferably detachably attached to the valve body.

The nozzle 51 has one or more nozzle holes 52. The nozzle 51 and the nozzle hole 52 are configured to inject ammonia into the prechamber 33.

The ammonia valve 50 can be of the type controlled by a control signal to perform an ammonia injection event. This type of ammonia valve 50 can be connected to a common rail type ammonia supply source that is maintained at a substantially constant pressure. The control signal is synchronized with the engine cycle so that the timing of the ammonia injection is appropriate.

In an alternative example, the ammonia valve 50 is a type of valve that opens when the supply pressure at the ammonia inlet port exceeds a given threshold and closes when the supply pressure at the ammonia inlet port falls below a given threshold. be able to. The latter type of ammonia valve 50 requires a connection to a pressure variable pressurized liquid phase ammonia source that is controlled synchronously with the engine cycle.

A prechamber 33 is associated with each ammonia valve 50. The prechamber 33 forms part of the cylinder cover 22, preferably in the form of an insert 55 attached to the cylinder cover 22, and is preferably detachably attached. By using the pre-chamber 33 as the insert 55, the pre-chamber 33 can be maintained or repaired by simply replacing the insert 55 without replacing or repairing the entire cylinder cover 22. can. In the embodiment shown in FIG. 7, the prechamber 33 is formed as a single unit together with the ammonia valve 50. This single unit is an insert attached to the cylinder cover 22, preferably detachably attached, as in the previous example.

The brichamber 33 allows fluid to flow to and from the combustion chamber through the opening 35. The cross-sectional area of the opening 35 is preferably larger than the cross-sectional area of the entire plurality of nozzle holes 52 of the nozzle 51. More preferably, the cross-sectional area of the opening 35 is twice or more the cross-sectional area of the entire plurality of nozzle holes 52 of the nozzle 51.

The wall separating the prechamber 33 from the combustion chamber forms a protrusion from the cylinder cover 22 to the combustion chamber. Preferably, the opening 35 forms part of the wall forming the protrusion. By making the wall a protrusion to the combustion chamber, the wall can be heated during the operation of the engine, whereby the prechamber 33 can be heated during the operation of the engine, which is within the prechamber. Helps improve the stability of the ammonia jet.

In some embodiments, an ignition fluid valve 60 (see FIG. 6) is associated with the prechamber 33. In this example, the ignition fluid valve 60 is attached to the cylinder cover 22 at the portion of the ignition fluid nozzle 61. The ignition fluid nozzle 61 has a nozzle hole 62. These are configured to be ignited fluid into the prechamber 33 by the action of the ignition fluid valve 60. The ignition fluid valve 60 has an inlet port connected to a source 44 of the pressurized ignition fluid. In some embodiments, the ignition fluid is a pilot fluid. That is, the fluid is injected immediately before or at the same time as the start of fuel injection into the prechamber. The ignition fluid can be, for example, fuel oil (eg diesel oil), DME, hydrogen, or the like. (Hydrogen can be used as a pilot fluid or ignition accelerator.) The operation of the ignition fluid valve 60 is such that the ignition fluid is injected into the prechamber 33 before and / or with ammonia. Synchronized with the engine cycle. Therefore, an engine according to an embodiment injects pilot fluid through the nozzle 61 of the ignition fluid valve 60 and then only ammonia through the nozzle 51 of the ammonia valve 60, or the pilot fluid through the ignition fluid valve 60. And inject both ammonia through the ammonia valve 60.

In another embodiment, the ignition promoting medium is added to the ammonia before or when it is injected into the prechamber. In some embodiments, the ignition accelerator is hydrogen. This hydrogen is mixed with the ammonia in the gas phase. Another medium with suitable ignition characteristics may be used. .. In the case of liquid phase ammonia, the ignition accelerator is also a liquid phase substance and can therefore be mixed with liquid phase ammonia. In the case of vapor phase ammonia, the ignition accelerator is also a gas phase substance and can therefore be mixed with the vapor phase ammonia.

In some embodiments, the engine is configured to simultaneously inject ammonia and other fuels into the prechamber 33. In some embodiments, the other fuel is a conventional hydrocarbon fuel such as fuel oil or natural gas. That is, the other fuel can also be of a liquid phase or a gas phase. Ammonia can be supplied to the ammonia valve 50 in liquid or gas phase.

As shown in FIG. 5a, the engine of this embodiment includes a fuel valve 70 having a nozzle 71. The nozzle 71 has a nozzle hole 72 that opens into at least one prechamber 33. The fuel valve 70 has an inlet port connected to a source 49 of other pressurized fuel. The fuel valve 70 is configured to inject the other fuel from the source 49 into the prechamber 33 through the nozzle holes 72.

A control unit (not shown) is configured to control engine operation, including the operating and stopping times of the ammonia valve 50 and the ignition fluid valve 60.

By injecting the pilot fluid before injecting ammonia, it is possible to raise the temperature inside the prechamber 33 to a temperature sufficient for the ammonia to ignite when it enters the prechamber 33. Further in this embodiment, the prechamber 33 ensures that the pilot fuel and ammonia are mixed. This is because they are discharged from the prechamber 33 to the main combustion chamber.

The prechamber 33 allows the ignition fluid and ammonia to mix before entering the combustion chamber. This allows for a uniform distribution of ammonia and the igniting fluid. The ignition fluid is therefore part of the ammonia jet that escapes the prechamber 33 through the opening 35, allowing proper use of the ignition fluid for stabilizing the combustion process. The rise in temperature of the air (compressed scavenging) and the prechamber wall is most noticeable during the initial stages of ammonia injection. This also solves the problems associated with high evaporative cooling of ammonia. The prechamber 33 therefore eliminates, or at least minimizes, the amount of ignition fluid required by proper mixing and improved temperature transfer from the wall surface.

Stable combustion of ammonia in direct injection mode results in significant improvements in combustion control and combustion stability.

The nozzles or atomizers 51, 61 are arranged in the prechamber 33, which also has the effect of protecting the nozzles or atomizers 51, 61 from the harsh environment in the combustion chamber.

Many aspects and implementations have been described with some examples. However, considering the specification, drawings, and claims of the present application, those skilled in the art have many variations in carrying out the inventions described in the claims in addition to the described examples. You will be able to understand and embody that. The terms "prepared", "have", and "include" described in the claims do not exclude the existence of elements or steps that are not described. Even if it is not explicitly stated that the number of elements described in the claims is multiple, it does not exclude the existence of multiple elements. Even if some matters are described in separate dependent claims, it does not exclude the combined implementation of these matters, and the combined implementation can be profitable.

The reference numerals used in the claims shall not be construed as limiting the scope of the invention. Unless otherwise stated, the drawings are intended to be read with the specification and are part of the entire disclosure of this application. In the specification, the terms "horizontal", "vertical", "left", "right", "upper", and "lower", as well as their adjective and adjunct forms (for example, "horizontally", "rightward", and "upward"). The term "etc.) merely refers to the orientation of the structure illustrated in the direction the reader sees it. Similarly, the terms "inwardly" and "outwardly" generally refer to the orientation of a surface with respect to a longitudinal axis or a rotation axis, depending on the situation.

Claims (16)

A large two-stroke turbocharged uniflow scavenging compression ignition internal combustion engine configured to operate on ammonia as the main fuel or sole fuel in at least one mode of operation.
With at least one cylinder provided in the cylinder liner having a reciprocating piston inside, a cylinder cover covering itself, and a cylinder liner where the scavenging port is located.
A combustion chamber formed between the reciprocating piston in the cylinder and the cylinder cover,
The exhaust valve arranged in the center of the cylinder cover and
With at least one prechamber located on the cylinder cover and connected to the combustion chamber to allow fluid to flow through the openings.
An ammonia valve having a nozzle provided with a plurality of nozzle holes opening to at least one prechamber,
Equipped with
The ammonia valve has an inlet port connected to a source of pressurized ammonia.
The ammonia valve is configured to inject liquid ammonia from the source into the prechamber through the nozzle holes.
institution. The ignition fluid valve is provided with an ignition fluid valve associated with the at least one prechamber, the ignition fluid valve comprises an ignition fluid nozzle having nozzle holes, and the ignition fluid valve is connected to a source of pressurized ignition fluid, claim. The institution described in 1. The engine according to claim 2, wherein the ignition fluid valve is configured to inject the ignition fluid into the prechamber through the nozzle. The engine according to claim 2 or 3, wherein the source of the pressurized ignition fluid is a source of the pressurized pilot fluid or a source of the pressurized ignition accelerator. The pilot fluid is injected through the nozzle of the ignition fluid valve and then only ammonia is injected through the nozzle of the ammonia valve, or both the pilot fluid through the ignition fluid valve and ammonia are injected through the ammonia valve. The institution according to any one of claims 2 to 4, which is configured to be such. The engine according to any one of claims 1 to 5, wherein the prechamber is an insert arranged in the cylinder cover, preferably an insert that is detachably attached. 6. The prechamber, wherein the prechamber forms a single unit with the ammonia valve, wherein the single unit is an insert that is attached to the cylinder cover, preferably a removable attachment. institution. At least a part of the wall separating the prechamber from the combustion chamber forms a protrusion from the cylinder cover into the combustion chamber, preferably a protrusion from the side surface of the cylinder cover facing the combustion chamber. The institution according to any one of claims 1 to 7. The engine according to any one of claims 1 to 8, wherein the total cross-sectional area of the plurality of nozzle holes is smaller than the cross-sectional area of the opening, preferably considerably smaller, and more preferably less than half. The engine according to any one of claims 1 to 9, which has a plurality of prechambers arranged around the exhaust valve. The engine according to any one of claims 1 to 10, wherein the source of pressurized ammonia is a source of pressurized liquid phase ammonia. The engine according to any one of claims 1 to 11, configured to simultaneously inject ammonia and other fuels into the prechamber. The fuel valve comprises a fuel valve having a nozzle with a nozzle hole that opens into the at least one prechamber, the fuel valve having an inlet port connected to a source of other pressurized fuel, said from said source. 12. The engine of claim 12, configured to inject other fuel into the prechamber through the nozzle holes of the fuel valve. A modification kit for a compression ignition internal combustion engine, the modification kit for making the engine suitable to operate on ammonia as the main fuel or the sole fuel in at least one mode of operation. It is a kit, where the institution is
With at least one cylinder having a reciprocating piston inside and a cylinder cover covering itself,
A combustion chamber formed between the reciprocating piston in the cylinder and the cylinder cover,
The modified kit is equipped with
A prechamber that is attached to the cylinder cover and has an opening for connecting the prechamber to the combustion chamber.
An ammonia valve having a nozzle provided with a plurality of nozzle holes opening to at least one prechamber,
Equipped with
The ammonia valve has an inlet port connected to a source of pressurized liquid ammonia.
The ammonia valve is configured to inject liquid ammonia from the source into the prechamber through the nozzle holes.
Remodeling kit. The modified kit of claim 14, wherein the prechamber forms an insert mounted on the cylinder cover, preferably a removable mount. 15. The prechamber forms a single unit with the ammonia valve, wherein the single unit is an insert mounted on the cylinder cover, preferably a removable mount. The modified kit described.

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