CN116981883A

CN116981883A - Arrangement for burning purge gas and method thereof

Info

Publication number: CN116981883A
Application number: CN202280018912.4A
Authority: CN
Inventors: T·默克索伦森; S·莫嘉尔德; L·斯凯特乔根森
Original assignee: Alfa Laval Corporate AB
Current assignee: Alfa Laval Corporate AB
Priority date: 2021-03-19
Filing date: 2022-03-15
Publication date: 2023-10-31
Also published as: EP4060230A1; KR20230156369A; WO2022194804A1; TWI826962B; TW202248569A; JP2024508927A

Abstract

An arrangement (100) and method for combusting a purge gas derived from an ammonia fuel system (108) for fueling an ammonia fuel engine (112), the arrangement (100) comprising: a boiler system (102), comprising: a burner (104), a fuel inlet (111) configured to supply fuel and thereby maintain a supporting flame in the burner (104), and a purge gas inlet (121) configured to intermittently receive a purge gas from an ammonia-fuelled engine (112) and to supply the purge gas to the burner (104), the purge gas comprising a mixture of ammonia and an inert gas, wherein the burner (104) is configured to combust the ammonia with the supporting flame.

Description

Arrangement for burning purge gas and method thereof

Technical Field

The present disclosure relates to an arrangement for combusting purge gas derived from an ammonia fuel system for fueling an ammonia fuelled engine and a method thereof.

Background

Marine engines powered by oil or gas are well known in the art. Boilers for combusting oil and gas for marine steam generation are also well known in the art. Typically, the selection of fuel for boiler operation is made with respect to the fuel selected for marine engine operation. Thus, if the marine engine is powered by oil, the boiler is typically also powered by oil. However, the marine engine and the boiler may be powered by different fuels.

One disadvantage of most marine engines today is marine air pollution, especially carbon dioxide (CO) emitted from marine engines when providing propulsion power ₂ ). It is generally agreed that from an environmental point of view, it is necessary to reduce CO ₂ Emissions and other greenhouse gas emissions. As a solution, alternative fuels are attractive in the marine industry. This includes fuels such as methanol, hydrogen, ammonia or converted biological materials. However, by introducing alternative fuels, other problems may occur, such as other environmental problems. For example, by powering marine engines with some of the alternative fuels, gases derived from these fuels may often not be directly vented to the atmosphere, for example due to toxicity, and often need to be eliminated prior to venting to the atmosphere. The latter is the case, for example, when ammonia is used as fuel. Thus, while alternative fuels may be more environmentally friendly in terms of greenhouse gas emissions than conventional fuels, there are other problems that need to be overcome.

To solve some parts of this problem, document CN109140496 discloses a boiler ignition device using an ammonia purge gas as a heat source, which includes a purge gas supply line and an ignition gas supply line.

However, as will be explained below, the prior art does not disclose a more environmentally friendly marine arrangement that fully meets the ganged design criteria that makes possible the use of alternative fuels and at the same time provides for no or limited amounts of toxic gases to be discharged to the atmosphere, and especially when it comes to meeting said ganged design criteria, the prior art does not disclose how to provide an overall arrangement that is used in a convenient manner over time.

Disclosure of Invention

It is an object of the present disclosure to provide a more environmentally friendly marine arrangement that fully meets the set of design criteria that makes possible the use of alternative fuels and at the same time provides for no or limited amounts of toxic gases to be vented to the atmosphere.

This object has been achieved by an arrangement for combusting a purge gas originating from an ammonia fuel system for fueling an ammonia fuelled engine, comprising:

a boiler system, comprising

The air flow of the burner is controlled by the air flow of the burner,

a fuel inlet configured to supply fuel and thereby maintain a supporting flame in the combustor, and

a purge gas inlet configured to intermittently receive a purge gas from the ammonia fuel system and supply the purge gas to the burner, the purge gas comprising a mixture of ammonia and an inert gas,

wherein the burner is configured to combust ammonia with a supporting flame.

Preferably, the ammonia fuel engine is a marine engine. Ammonia-fueled engines are advantageous because they use more environmentally friendly fuels (i.e., ammonia) to power the engine than most fossil fuels (e.g., oil and gas) in use today. This arrangement is advantageous because it burns the purge gas from the ammonia fuel system rather than venting the purge gas to the atmosphere. The purge gas may be generated when the ammonia fuel engine switches fuel from ammonia to another fuel or when the ammonia fuel engine is shut down in a controlled manner or due to an emergency. At this stage, the purge gas is toxic and therefore should not be vented to atmosphere. Instead, the purge gas inlet receives purge gas from the ammonia fuel system and supplies the purge gas to the burner. By combusting the mixture in the burner, the purge gas is discharged to the atmosphere as a combustion gas consisting essentially of nitrogen and water, rather than as a toxic gas. Thus, it can be said that this arrangement acts as a safety mechanism by burning the purge gas in the burner rather than discharging toxic gases to the atmosphere. Hereby, a more environmentally friendly marine arrangement is achieved that uses an alternative fuel, i.e. ammonia, and at the same time provides for no or as little toxic gases to be emitted to the atmosphere as possible.

Preferably, the ammonia-fueled engine operates on ammonia in pure form. However, it should be noted that ammonia may include a small amount of water. It should also be noted that ammonia may be mixed with another fuel, for example, an alcohol such as methanol or ethanol or a gas such as hydrogen. If ammonia is too difficult to utilize to support flame combustion, it may be advantageous to mix the ammonia with another fuel.

The purge gas may comprise a mixture of ammonia and an inert gas. The inert gas may be nitrogen. Preferably, the nitrogen is compressed nitrogen. However, it should be noted that other inert gases may be used. It should also be noted that if ammonia is mixed with another fuel, the purge gas will also include the other fuel. Fuel may be supplied first to provide a pilot flame and may also be supplied as the main fuel when the burner is operating in an operational mode. When the fuel is supplied to provide a pilot flame, the fuel may be small so that a small flame for igniting the main fuel may be provided. The pilot flame may be used to ignite the fuel supplied as the main fuel. When the fuel is supplied as the main fuel, the fuel is supplied in a larger amount than the fuel supplied for providing the pilot flame. Preferably, when combusting ammonia, the main fuel acts as a supporting flame, so that the purge gas is combusted with the supporting flame. The support flame must be of a certain size to ensure complete combustion of the ammonia.

Preferably, when starting up to burn the purge gas, the boiler may be operated at 15-50%, preferably 25-50% compared to full operation in the following sense: the support flame may be maintained by supplying fuel at a rate of 15-50%, preferably 25-50% compared to the rate at which the fuel is supplied when the boiler is operating in full operation, thereby ensuring that ammonia supplied to the burner is also combusted when the burner is started for the purpose of combusting the purge gas and not started in operation in full operation to generate heat. In this context, it may be noted that the generation of heat may refer to the generation of steam, heating hot water, heating a hot fluid, or any other medium used in a heating boiler. The support flame must generally be larger than the pilot flame because the purge gas is generally more difficult to ignite than the main fuel. The fuel inlet and the purge gas inlet may be separate inlets. However, if the purge gas includes both a gas and a liquid, the liquid may be supplied to the burner by the fuel inlet and the gas may be supplied to the burner by the purge gas inlet, as will be discussed further below.

The burner may be of the steam atomizing type or of the pressure atomizing type. It should be noted that if the burner is of the steam atomizing type, fuel may be supplied to provide a pilot fuel for igniting the main fuel. If the burner is of the pressure atomizing type, the fuel is usually supplied only as main fuel. Instead, the pressure atomizing burner includes a spark igniter configured to ignite the main fuel. However, if the burner is of the steam atomizing type, fuel may be supplied to provide a pilot flame as a spark igniter for igniting the main fuel.

The boiler system may be configured to operate in one of at least a first mode and a second mode, wherein

The first mode is a heat generation mode in which heat is generated, and

the second mode is an ammonia safe purge mode, wherein the boiler remains warm and ready for fast operation and/or wherein the pilot flame is maintained.

The first mode may be the mode of operation discussed above. The second mode may be a ready mode in which the boiler is ready for quick operation or ready for quick start. In the first mode and the second mode, the burner may be an active burner. By the term "active burner" is meant herein a burner that is ready to receive purge gas via a purge gas inlet at any time (as the shut down of the engine may occur at any time). If the burner is an active burner, the burner is in an operational mode or in a ready mode, ready to receive purge gas.

The disclosed boiler system provides for a more flexible implementation of the boiler system. By having a more flexible boiler system it is possible to use the boiler system in more ways than just the main purpose of the burner, i.e. to generate heat. Thus, the boiler system may also be configured to combust the purge gas. Switching between different modes is provided in that a conventional burner (e.g. a fuel-oil burner or a gas burner) can be used to both generate heat and burn the purge gas. It should be noted, however, that the burner may be configured to operate in more than two modes.

The boiler system may be configured to operate in at least one of a first sub-mode and a second sub-mode of the first mode, wherein in the first sub-mode, the main flame is maintained in the burner for heat production and no purge gas is supplied to the burner, and in the second sub-mode, the main flame is maintained in the burner for heat production and purge gas is supplied to the burner and ammonia is combusted with the main flame serving as a supporting flame.

The first sub-mode of the first mode may be configured to generate heat from the main fuel. The second sub-mode of the first mode may be configured to generate heat from the main fuel and the purge gas to combust the purge gas.

The boiler system may be configured to ignite the supporting flame by first igniting the pilot flame and then igniting the supporting flame from the pilot flame, or if the pilot flame is maintained, directly igniting the supporting flame from the pilot flame, and supplying the purge gas to the burner and combusting ammonia with the supporting flame.

Preferably, the respective inlets are controllable by one or more valves. The one or more valves may be configured to open and close the fuel inlet and the purge gas inlet such that switching between at least two modes and/or between a first sub-mode and a second sub-mode of the first mode may be possible. The one or more valves may be configured to independently open and close the fuel inlet and to independently open and close the purge gas inlet.

The fuel inlet may be connected to a fuel source via a fuel supply line, and the fuel source may be configured to supply a fuel selected from the group consisting of Liquefied Natural Gas (LNG), distillate, and residual fuel. This may include, for example, diesel, marine light diesel (MGO), very Low Sulfur Fuel Oil (VLSFO), heavy Fuel Oil (HFO). The fuel may also be a biofuel. It should be noted that other types of fuels may also be used as the fuel, such as ammonia, hydrogen, and methanol. It should be noted that the fuel may include two types of fuels. The two types of fuel may be premixed with each other and supplied from the same fuel source, or may be kept separate and supplied from two different fuel sources. For example, the fuel source may be a tank. If the fuel comprises two types of fuel supplied from two different fuel sources, they may each have one supply line from the respective fuel tank to the burner, but they may also be shared. If the two types of fuel are each supplied with a supply line from two different fuel sources, they may also each have a fuel inlet, or alternatively there may be one fuel inlet connected to two different supply lines, so that fuel from two different fuel sources may be introduced into the burner from a common inlet. The other fuel source may be configured to supply a fuel selected from the group consisting of Liquefied Natural Gas (LNG), distillate, and residual fuel. This may include, for example, diesel, marine light diesel (MGO), very Low Sulfur Fuel Oil (VLSFO), heavy Fuel Oil (HFO). The fuel may also be a biofuel. It should be noted that other types of fuels may also be used as the fuel, such as ammonia, hydrogen, and methanol.

The arrangement may further comprise an ammonia fuel system comprising:

an ammonia fuel source for storing ammonia,

a fuel supply system is provided that is configured to supply fuel,

ammonia fuel engine, and

a purge source comprising an inert gas and configured to purge ammonia from a portion of the ammonia fuel system to the purge gas inlet by flushing the inert gas through the portion of the ammonia fuel system.

This is advantageous because it ensures that there is no unwanted fuel in the lines of the ammonia fuel system. Thus, when an ammonia-fueled engine is switched to fuel or shut down, as previously discussed, ammonia may be present in the line that should not be vented to the atmosphere nor supplied back to the ammonia fuel source. By flushing the inert gas through those parts of the ammonia fuel system, ammonia that may be left in the pipeline is forced out of the ammonia fuel system, forming a mixture of ammonia and inert gas, and this mixture may be directed towards the boiler system. It is contemplated that the mixture of ammonia and inert gas may also be a mixture of a gas phase and a liquid phase, which may be directed, for example, via an evaporator and/or a separator. Forcing ammonia from the ammonia fuel system by the inert gas is provided such that substantially all of the ammonia is discharged from the ammonia fuel system. Thereby a safer and environmentally friendly arrangement is achieved.

Ammonia may be purged from portions of the ammonia fuel system. Preferably, ammonia may be purged from portions near the engine, as ammonia within these portions may be dirty ammonia, and mixing of dirty ammonia back into the ammonia fuel source should be avoided.

Preferably, ammonia forced out of the ammonia fuel system should not be able to be forced to other parts within the ammonia fuel system, but rather out of the system. The ammonia fuel system may include one or more valves configured to control the flow of ammonia as the ammonia is forced out of the ammonia fuel system.

The arrangement may further include a fuel valve mechanism and recirculation of ammonia responsible for unnecessary purging. This may typically be ammonia, for example, present in those portions of the ammonia fuel system that are relatively close to the fuel tank. Such ammonia typically does not absorb too much dirt and water and can typically be returned to the fuel tank.

The mixture of ammonia and inert gas may include gaseous ammonia, liquid ammonia, and inert gas.

The arrangement may further include a vaporizer configured to vaporize the liquid ammonia into gaseous ammonia, thereby providing a gaseous mixture of ammonia and inert gas for supply to the burner. The mixture includes both liquid and gaseous ammonia, which is generally not optimal for the burner. Thus, burners typically require liquids or gases, but often do not work well with mixtures of the two. Thus, if the mixture can include both liquid and gas, it may be desirable to convert it to either liquid or gas. By introducing an evaporator in this arrangement, it is possible to evaporate liquid ammonia into gaseous ammonia, so that the purge supplied to the burner may comprise only purge gas. Thus, the evaporator may be advantageous in that it is provided to receive only gaseous purge by the burner. Preferably, the evaporator is arranged such that the purge gas is supplied to the evaporator before being supplied to the purge gas inlet.

The arrangement may further or alternatively comprise a separator configured to separate liquid ammonia from gaseous ammonia and inert gas, thereby providing a gaseous mixture of ammonia and inert gas for supply to the burner. By introducing a separator in this arrangement, it is possible to separate liquid ammonia from gaseous ammonia and inert gas, so that the purge supplied to the burner may comprise only purge gas. The separator may be a gas/liquid separator, typically a drum or tank with a mist eliminator in the outlet. The purged liquid phase may be connected to a main fuel supply system such that the liquid phase is mixed with the liquid main fuel. It should be noted that the arrangement may comprise both the evaporator and the separator, or only one of them.

The evaporator may for example be arranged downstream of the separator such that the purge gas from which the majority of the liquid phase has been removed at the separator is supplied to the evaporator before being supplied to the purge gas inlet.

The burner may be a multi-fuel burner configured to burn at least two different fuels one at a time or simultaneously. This is advantageous because more than one fuel may be configured to power or be combusted by the burner. The multi-fuel burner may be configured to burn at least two different fuels, preferably two different liquid fuels, preferably one at a time. The multi-fuel burner may be configured to combust one or more liquid fuels in combination with combusting one or more gaseous fuels, wherein the one or more liquid fuels, preferably one liquid fuel at a time, are combusted simultaneously with the combustion of the one or more gaseous fuels, preferably one gaseous fuel at a time.

The arrangement may further comprise a liquid ammonia inlet connected to the fuel supply line via a liquid ammonia connection such that the liquid ammonia is mixed with the fuel. This may be advantageous if the arrangement comprises a separator and/or an evaporator. If this is the case, the liquid ammonia separated from the purge gas may be configured to mix with the fuel and still reach the burner, but in a different mixture than the purge gas mixture.

The arrangement may further include a combustion fan configured to provide combustion air to the combustor. The combustion fan may be configured to supply a specific amount of combustion air based on preset requirements. Preferably, the combustion air in the boiler system should be 10-15% more than fuel. This combustion air ratio is typically required to fully combust not only the fuel but also the purge gas. Incomplete combustion, if not complete, can result in furnace fouling and having a higher carbon monoxide CO content than the desired black exhaust.

The arrangement may further include a gas valve mechanism configured to control the flow of purge gas supplied from the ammonia fuel system to the combustor.

The combustion fan may be further or alternatively configured to direct the purge gas to the combustor. The combustion fan may include a purge gas inlet, wherein the combustion fan may be configured to mix the purge gas with combustion air and provide a mixture of the purge gas and the combustion air to the combustor.

The gas valve mechanism may be excluded from this arrangement if the combustion fan is configured to direct purge gas to the burner. Instead, the combustion fan may be arranged to control and direct the flow of purge gas supplied from the ammonia fuel system to the burner. In the combustion fan, the purge gas may be mixed with the combustion air. The mixture may be directed to a burner where the mixture may be combusted with a supporting flame. However, it should be noted that the arrangement may include both a combustion fan and a gas valve mechanism for directing the purge gas. The combustion fan may be designed for a purge gas. The purge gas inlet included in the combustion fan ensures optimal mixing with the combustion air. In addition, the combustion fan may be arranged to prevent backflow of the purge gas.

Furthermore, if the arrangement comprises an evaporator and/or a separator, the combustion fan is preferably arranged downstream of the evaporator and/or the separator.

The above-mentioned object is also achieved by a method for combusting a purge gas originating from an ammonia fuel system for fueling an ammonia-fuelled engine, the method comprising:

maintaining a support flame in a burner included in the boiler system, wherein the support flame is maintained by fuel supplied through a fuel inlet; and

intermittently supplying a purge gas, wherein the purge gas is supplied from the ammonia fuel system to the burner by a purge gas inlet, the purge gas comprising a mixture of ammonia and an inert gas, and

the ammonia is combusted in the burner with a supporting flame.

Thus, the method includes receiving purge gas from an ammonia fuel system in a combustor prior to combustion of ammonia.

According to the method, the boiler system may be configured to operate in one of at least a first mode and a second mode, wherein

The first mode is a heat generation mode in which heat is generated, and

The different further preferred embodiments mentioned above in connection with the arrangement are equally applicable to the method.

The arrangement is preferably placed on a ship. The method is preferably performed on board a ship. However, it may be noted that neither the arrangement nor the method is limited to use on board a ship. The arrangement and method may be useful for other applications where there is an engine and boiler located close to each other. This may be the case, for example, in other marine applications besides vessels. It may for example be a platform, such as of the type used for drilling oil or gas. The arrangement and method may also be used for land-based applications. The arrangement and method may be used, for example, in logging or mining applications.

In general, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, device, component, means, step, etc" are to be interpreted openly as referring to at least one instance of said element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Drawings

The above and additional objects, features and advantages of the present disclosure will be better understood from the following exemplary and non-limiting detailed description of preferred embodiments thereof with reference to the accompanying drawings, in which like reference numerals will be used for like elements, wherein:

fig. 1 discloses an arrangement for combusting purge gas originating from an ammonia-fueled engine.

Fig. 2 discloses a flow chart illustrating a method for combusting purge gas from an ammonia-fueled engine.

Detailed Description

The present disclosure now will be described more fully hereinafter with reference to the accompanying drawings, in which presently preferred embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

Referring to FIG. 1, an arrangement 100 for combusting purge gas derived from an ammonia fuel system 108 that fuels an ammonia fuel engine 112 is disclosed. The arrangement 100 includes a boiler system 102 and an ammonia fuel system 108. The ammonia fuel system 108 includes an ammonia fuel engine 112.

The purge gas may be generated when the ammonia fuel engine 112 switches fuel from ammonia to another fuel or when the ammonia fuel engine 112 is shut down in a controlled manner or due to an emergency. At this stage, the purge gas is toxic and therefore should not be vented to atmosphere. The purge gas is typically a mixture of ammonia and an inert gas for purging ammonia from the ammonia fuel system 108. The ammonia may be liquid ammonia, gaseous ammonia, or a mixture thereof. The inert gas may be nitrogen. It should be noted that the inert gas may also be any other inert gas.

The boiler system 102 includes a burner 104, a fuel inlet 111, and a purge gas inlet 121. The combustor 104 is configured to combust a purge gas derived from the ammonia fuel system 108. In other words, the combustor 104 is configured to combust ammonia within the sweep gas. The combustor 104 may be a multi-fuel combustor configured to combust two different fuels at a time or simultaneously. The burner 104 may be of the pressure atomizing type. Alternatively, the burner 104 may be of the steam atomizing type.

The fuel inlet 111 is configured to supply fuel and thereby maintain a supporting flame in the combustor 104. The fuel inlet 111 is generally configured to continuously supply fuel, and at least in the sense that it is capable of sustaining a supporting flame. Fuel may be supplied first to provide a pilot flame and may also be supplied as the main fuel when the burner is operating in an operational mode. The main fuel may act as a support flame so that the purge gas may be combusted with the support flame.

The purge gas inlet 121 is preferably separate from the fuel inlet 111. The purge gas inlet 121 is configured to intermittently receive purge gas from the ammonia fuel system 108 and supply the purge gas to the combustor 104. Purge gas may be supplied from the ammonia fuel system 108 to the purge gas inlet 121 via a purge gas line 123. The conduit 123 may be of the double-wall type; especially for those portions of line 123 where the purge is in the gas phase.

The fuel inlet 111 may be connected to a fuel source 115, such as a fuel tank, via a fuel supply line 113. The fuel source 115 is configured to supply fuel to the combustor 104 via the fuel inlet 111. The fuel may be Liquefied Natural Gas (LNG), distillate, and residual fuel. This may include, for example, diesel, marine light diesel (MGO), very Low Sulfur Fuel Oil (VLSFO), heavy Fuel Oil (HFO). The fuel may also be a biofuel. It should be noted, however, that the main fuel may also be other fuels. The fuel may include one or more types of fuel. If the fuel includes more than one type of fuel, the fuel inlet 111 may be connected to more than one fuel source. Thus, if the fuel includes two types of fuel, one fuel type may be supplied from the fuel source 115 and another fuel type may be supplied from the other fuel source 135. Typically, only one fuel at a time is supplied to the combustor 104. Typically, as shown in FIG. 1, the fuel supply line 113 is operated, wherein different fuels are provided one at a time (although at different times) using the same inlet 111. One conceivable combination is to provide liquid fuel to inlet 111 via fuel supply line 113 and at the same time provide gas via a separate gas inlet, such as via combustion fan 120. The gas provided via the separate gas inlet (such as combustion fan 120) may be a purge gas, and/or it may be a gaseous fuel that is not derived from a purge operation.

However, the fuel supply line 113 as shown in fig. 1 may be used to mix two types of fuel in the fuel supply line 113 if desired, wherein another fuel may be supplied to the fuel supply line 113 by another fuel supply line 133 such that the mixture is supplied to the burner 104 via the fuel inlet 111. However, although not shown, both types of fuel may be supplied to the combustor 104 by two different fuel inlets via two different supply lines. Accordingly, the arrangement 100 may include an additional supply line disposed separately from the fuel supply line 113, wherein the additional supply line may be disposed to supply another fuel from another fuel source 135 to the combustor 104. The other fuel may be any of the fuels listed above with respect to the fuel. Preferably, if the fuel comprises two types of fuel, one type may be a liquid fuel and the other type may be a gaseous fuel.

Referring to FIG. 2, a flow chart 200 is shown by way of example, the flow chart 200 illustrating a method 200 for combusting purge gas derived from an ammonia fuel system 108 that fuels an ammonia fuel engine 112. The boiler system 102 is configured to operate in a first mode 201. The boiler system 102 is configured to operate in a second mode 211. The boiler system 102 may be configured to operate in other modes than the first mode 201 and the second mode 211. The first mode 201 may be a heat generation mode in which heat is generated. In this context, it may be noted that the generation of heat may refer to the generation of steam, heating hot water, heating a hot fluid, or any other medium used in a heating boiler. The second mode 211 may be an ammonia safe purge mode, wherein the boiler 106 remains warm and ready for fast operation and/or wherein a pilot flame may be maintained. A boiler 106 is included in the boiler system 102. In the second mode 211, the boiler may be ready for quick operation or ready for quick start.

The boiler system 102 may be configured to operate in a first sub-mode 201a and a second sub-mode 201b of the first mode 201. In the first sub-mode 201a, the main flame is maintained in the burner 104 for heat generation, and no purge gas is supplied to the burner 104. The first sub-mode 201a is configured to generate heat from fuel supplied to the combustor 104 by the fuel inlet 111. The second sub-mode 201b of the first mode 201 is configured to generate heat from the main fuel and the purge gas, wherein the purge gas is supplied by the purge gas inlet 121. Thus, in the second sub-mode 201b, the main flame is maintained in the burner 104 for heat generation, and the purge gas is supplied to the burner 104. Ammonia is combusted with a main flame acting as a supporting flame.

The boiler system 102 is configured to ignite the support flame by first igniting a pilot flame or a pilot spark and then igniting the support flame from the pilot flame. The boiler system 102 is configured to ignite the support flame directly from the pilot flame if the pilot flame is maintained, and to supply purge gas to the burner 104 and combust ammonia with the support flame.

Thus, both the first mode and the second mode are configured to combust ammonia, but have different starting points.

Referring back to FIG. 1, the ammonia fuel system 108 includes an ammonia fuel source 155, a fuel supply system 110, and an ammonia fuel engine 112. The ammonia fuel system 108 may include a purge source 165. The ammonia fuel source 155 may be an ammonia tank and configured to store ammonia prior to supply to the ammonia fuel engine 112. The fuel supply system 110 is configured to supply ammonia within the ammonia fuel system 108. The ammonia fuel engine 112 is configured to be powered by ammonia supplied from an ammonia fuel source 155.

Purge source 165 is typically a gas canister containing an inert gas. Inert gas from purge source 165 is configured to purge ammonia from ammonia fuel system 108 to purge gas inlet 121 by flushing inert gas through ammonia fuel system 108. The arrangement 100 may include a gas valve mechanism 118 configured to control the flow of purge gas supplied from the ammonia fuel system 108 to the combustor 104. As discussed above, the purge gas is a mixture of ammonia and an inert gas. The ammonia may be liquid ammonia, gaseous ammonia, or a mixture thereof. If the ammonia is a mixture of gaseous ammonia and liquid ammonia, the purge gas is a mixture of gas and liquid. The purge gas supplied to the burner 104 should be in gaseous form and thus liquid must be removed from the purge gas before being supplied to the burner 104.

The arrangement 100 may include an evaporator 114 configured to evaporate liquid ammonia (if present in the mixture) into gaseous ammonia. By vaporizing the liquid ammonia into gaseous ammonia, a gaseous mixture of ammonia and inert gas may be supplied to the combustor 104. The evaporator 114 may be disposed within the purge gas line 123, between the boiler system 102 and the ammonia fuel system 108.

The arrangement 100 may further or alternatively comprise a separator 116 configured to separate liquid ammonia from gaseous ammonia and inert gas (if present in the mixture). By separating liquid ammonia from gaseous ammonia and inert gas, a gaseous mixture of ammonia and inert gas may be supplied to the combustor 104. The separator 116 may be disposed within the purge gas line 123 between the boiler system 102 and the ammonia fuel system 108.

It should be noted that the arrangement 100 may comprise both the evaporator 114 and the separator 116, or only one of the evaporator 114 and the separator 116.

The arrangement 100 may include a liquid ammonia inlet 141. The liquid ammonia inlet 141 may be connected to the fuel line 133 via a liquid ammonia line 143. The liquid ammonia inlet 141 may be configured to supply liquid ammonia from the evaporator 114 and/or the separator 116 to the fuel line 133 such that the liquid ammonia may be mixed with fuel disposed in the fuel line 133. Thus, liquid ammonia may be supplied to the combustor 104 as a mixture with fuel.

The arrangement 100 may include a combustion fan 120. The combustion fan 120 may be configured to provide air to the combustor 104 for combustion of the ammonia. The combustion fan 120 may be configured to supply a specific amount of air based on preset requirements. The combustion fan 120 may be further or alternatively configured to direct the purge gas to the combustor 104. The combustion fan may be further or alternatively configured to direct the purge gas to the combustor. The combustion fan 120 may include a purge gas inlet 121, wherein the combustion fan 120 may be configured to mix the purge gas with the combustion air. The combustion fan 120 may be further arranged to direct a mixture of purge gas and combustion air to the combustor 104. Those skilled in the art will recognize that the present disclosure is in no way limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

Claims

1. An arrangement (100) for combusting a purge gas originating from an ammonia fuel system (108) for fueling an ammonia fuel engine (112), the arrangement (100) comprising:

a boiler system (102) comprising

A burner (104),

a fuel inlet (111) configured to supply fuel and thereby maintain a supporting flame in the burner (104), and

a purge gas inlet (121) configured to intermittently receive a purge gas from the ammonia fuel system (108) and supply the purge gas to the burner (104), the purge gas comprising a mixture of ammonia and an inert gas,

wherein the burner (104) is configured to combust the ammonia with the support flame.

2. The arrangement (100) of claim 1, wherein the boiler system (102) is configured to operate in one of at least a first mode (201) and a second mode (211), wherein

The first mode (201) is a heat generation mode in which heat is generated, and

the second mode (211) is an ammonia safe purge mode, wherein the boiler (106) remains warm and ready for fast operation and/or wherein a pilot flame is maintained.

3. The arrangement (100) of claim 2, wherein the boiler system (102) is configured to operate in one of at least a first sub-mode (201 a) and a second sub-mode (201 b) of the first mode (201), wherein in the first sub-mode (201 a) a main flame is maintained in the burner (104) for heat generation and no purge gas is supplied to the burner (104), and in the second sub-mode (201 b) the main flame is maintained in the burner (104) for heat generation and purge gas is supplied to the burner (104) and the ammonia is combusted with the main flame acting as the support flame.

4. An arrangement (100) according to claim 2 or claim 3, wherein the boiler system (102) is configured to

Igniting a supporting flame by first igniting a pilot flame and then igniting the supporting flame from the pilot flame, or directly igniting the supporting flame from the pilot flame if the pilot flame is maintained, and

a purge gas is supplied to the burner (104) and the ammonia is combusted with the support flame.

5. The arrangement (100) according to any one of the preceding claims, wherein the fuel inlet (111) is connected to a fuel source (115, 135) via a fuel supply line (113, 133), the fuel source (115, 135) being configured to supply a fuel selected from the group consisting of Liquefied Natural Gas (LNG), distillate oil and residual fuel.

6. The arrangement (100) according to any one of the preceding claims, further comprising the ammonia fuel system (108), the ammonia fuel system (108) comprising:

an ammonia fuel source (155) for storing ammonia,

a fuel supply system (110),

the ammonia fuel engine (112), and

a purge source (165) containing the inert gas and configured to purge ammonia from the ammonia fuel system (108) to the purge gas inlet (121) by flushing the inert gas through the ammonia fuel system (108).

7. The arrangement (100) according to any one of claims 1 to 6, wherein the mixture of ammonia and inert gas comprises gaseous ammonia, liquid ammonia and inert gas.

8. The arrangement (100) of claim 7, wherein the arrangement (100) further comprises an evaporator (114) configured to evaporate liquid ammonia into gaseous ammonia, thereby providing a gaseous mixture of ammonia and inert gas for supply to the burner (104).

9. The arrangement (100) according to claim 7 or claim 8, wherein the arrangement (100) further comprises a separator (116), the separator (116) being configured to separate the liquid ammonia from the gaseous ammonia and inert gas, thereby providing a gaseous mixture of ammonia and inert gas for supply to the burner (104).

10. The arrangement (100) according to any one of the preceding claims, wherein the burner (104) is a multi-fuel burner configured to

Combusting at least two different fuels, preferably two different liquid fuels, preferably one at a time, or

In combination with combusting one or more gaseous fuels to combust one or more liquid fuels, wherein the one or more liquid fuels, preferably one liquid fuel at a time, are combusted simultaneously with the combustion of the one or more gaseous fuels, preferably one gaseous fuel at a time.

11. The arrangement (100) according to any one of the preceding claims, further comprising a combustion fan (120), the combustion fan (120) comprising the purge gas inlet (121), wherein the combustion fan (120) is configured to mix the purge gas with combustion air and to provide a mixture of purge gas and combustion air to the burner (104).

12. The arrangement (100) according to any one of the preceding claims, wherein the inert gas is nitrogen.

13. A method (200) for combusting a purge gas derived from an ammonia fuel system (108) that fuels an ammonia fuel engine (112), the method (200) comprising:

maintaining a support flame in a burner (104) included in a boiler system (102), wherein the support flame is maintained by fuel supplied through a fuel inlet (111); and

intermittently supplying the purge gas, wherein the purge gas is supplied from the ammonia fuel system (108) to the burner (104) by a purge gas inlet (121), the purge gas comprising a mixture of ammonia and an inert gas, and

-combusting the ammonia with the supporting flame in the burner (104).

14. The method (200) of claim 13, wherein the boiler system (102) is configured to operate in one of at least a first mode (201) and a second mode (211), wherein

The first mode (201) is a heat generation mode in which heat is generated, and

the second mode (211) is an ammonia safe purge mode, wherein the boiler remains warm and ready for fast operation and/or wherein a pilot flame is maintained.