JP7703676B2 - Apparatus and method for burning purge gas - Patents.com - Google Patents

Description

The present disclosure relates to an apparatus and method for combusting purge gas from an ammonia fuel system that fuels an ammonia-fueled engine.

Marine engines powered by oil or gas are well known in the art. Oil and gas fired boilers for marine steam production are also well known in the art. Typically the selection of fuel for boiler operation is made in conjunction with the fuel selected for marine engine operation. So, when the marine engine is oil powered, the boiler is often oil powered as well. However, the marine engine and boiler may be powered by different fuels.

One drawback with most of today's marine engines is marine air pollution, in particular carbon dioxide (CO ₂ ), which is emitted by marine engines when providing propulsion. It is generally agreed that CO ₂ emissions, as well as other greenhouse gas emissions, must be reduced in light of environmental aspects. As a solution, alternative fuels are gaining traction in the maritime industry. This includes fuels such as methanol, hydrogen, ammonia or conversion of biomaterials. However, by introducing alternative fuels, other problems may arise, such as other environmental problems. For example, by running marine engines on some alternative fuels, gases resulting from those fuels often must not be released directly into the atmosphere, for example due to toxicity, and often need to be scrubbed before being released into the atmosphere. This latter is the case, for example, when ammonia is used as fuel. So, although alternative fuels may be more environmentally friendly in terms of greenhouse gas emissions compared to traditional fuels, there are still other problems that need to be overcome.

In an attempt to address some of this problem, document CN109140496 discloses a boiler ignition system using ammonia purge gas as a heat source, including a purge gas supply pipeline and an ignition gas supply pipeline.

However, as will be explained below, the prior art does not disclose a more environmentally friendly marine system that adequately addresses a set of design criteria that allows for the use of alternative fuels while providing for no or limited amounts of toxic gases being released into the atmosphere, and in particular the prior art does not disclose how to provide an overall system that can be easily adapted over time to meet said set of design criteria.

CN109140496

The objective of the present disclosure is to provide a more environmentally friendly marine system that adequately addresses a set of design criteria that allows for the use of alternative fuels while providing for no or limited amounts of toxic gases being released into the atmosphere.

The object is achieved by an apparatus for combusting purge gas originating from an ammonia fuel system fuelling an ammonia-fuelled engine, the apparatus comprising:
Burna and
a fuel inlet configured to supply fuel to thereby maintain a support flame in the burner;
a purge gas inlet configured to intermittently receive purge gas from the ammonia fuel system and supply purge gas to the burner, the purge gas comprising a mixture of ammonia and an inert gas;
The burner is configured to combust ammonia with a supporting flame.
Equipped with a boiler system.

Preferably, the ammonia-fueled engine is a marine engine. The ammonia-fueled engine is advantageous because it uses an environmentally friendly fuel, i.e. ammonia, to run the engine compared to most fossil fuels used today, e.g. oil and gas. The device is advantageous because it burns the purge gas originating from the ammonia fuel system instead of releasing it to the atmosphere. Purge gas may be generated when the ammonia-fueled engine switches fuel from ammonia to another fuel, in a controlled manner or as a result of an emergency, or when the ammonia-fueled engine is shut down. At this stage, the purge gas is toxic and therefore should not be released to the atmosphere. Instead, a purge gas inlet receives the purge gas originating from the ammonia fuel system and supplies the purge gas to the burner. By burning the mixture in the burner, the purge gas is released to the atmosphere as combustion gases consisting mainly of nitrogen and water instead of as a toxic gas. Therefore, the device may be said to act as a safety mechanism by burning the purge gas in the burner instead of releasing toxic gas to the atmosphere. This achieves a more environmentally friendly marine system that uses an alternative fuel, namely ammonia, while ensuring that no or as few toxic gases are released into the atmosphere.

Preferably, an ammonia-fueled engine runs on ammonia in pure form. However, it should be noted that ammonia may contain trace amounts of water. It should further 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 burn with a supporting flame, it may be advantageous to mix it with another fuel.

The purge gas may include 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 as well. It should be further noted that if the ammonia is mixed with another fuel, the purge gas will include the other fuel as well. The fuel may be initially provided to provide a pilot flame, and may also be provided as the main fuel when the burner is running in an operational mode. When the fuel is provided to provide a pilot flame, the fuel may be in a small amount so that a small flame for ignition of the main fuel may be provided. The pilot flame may be for igniting the fuel being provided as the main fuel. When the fuel is provided as the main fuel, the fuel is provided in a large amount compared to the fuel provided to provide the pilot flame. Preferably, when burning ammonia, the main fuel is acting as a support flame such that the purge gas is burned in the support flame. The support flame must be of a certain size to ensure complete combustion of the ammonia.

Preferably, the boiler may be operated at 15-50%, preferably 25-50%, compared to full capacity, in the sense that when started to burn the purge gas, the support flame may be maintained by providing fuel at a rate of 15-50%, preferably 25-50%, compared to the rate at which fuel is provided when the boiler is running at full capacity, thereby ensuring that the ammonia provided to the burner is burned even when the burner is started for the purpose of burning the purge gas and is not running at full capacity when started to produce heat. It may be noted that in this context, the production of heat may refer to the production of steam, heating hot water, heating a thermal fluid, or heating any other medium used in the boiler. The support flame must typically be larger than the pilot flame, since the purge gas is typically difficult to ignite compared to the main fuel. The fuel inlet and the purge gas inlet may be separate inlets. However, as will be further described below, when the purge gas contains both gas and 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.

The burner may be of the steam atomized or pressure atomized type. It should be noted that if the burner is of the steam atomized type, fuel may be supplied to provide a pilot fuel for igniting the main fuel. If the burner is of the pressure atomized type, fuel is typically only supplied as the main fuel. Instead, pressure atomized burners include a spark igniter configured to ignite the main fuel. However, if the burner is of the steam atomized 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 at least one of a first mode and a second mode;
The first mode is a heat production mode in which heat is produced;
The second mode is an ammonia safe purge mode where the boiler is kept warm and ready for high speed operation and/or the pilot flame is maintained.

The first mode may be the operating mode described above. The second mode may be a preparation mode, in which the boiler is ready for high speed operation or is ready for a high speed start. In the first and second modes, the burner may be an active burner. By the term "active burner" is meant here a burner that is ready to receive purge gas via the purge gas inlet at any time, since engine shutdown may occur at any time. If the burner is an active burner, the burner is in an operating mode or in a preparation mode, in which it is ready to receive purge gas.

The disclosed boiler system provides for a more flexible boiler system to be achieved. By having a more flexible boiler system, it is possible to use the boiler system in more ways than just the primary purpose of the burner, i.e., to produce heat. The boiler system may therefore also be configured to burn purge gas. Switching between different modes provides for a conventional burner, e.g., an oil-fired burner or a gas-fired burner, to be used both to produce heat and to burn purge gas. However, it should be noted that the burner may be configured to operate in more than two modes.

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

A first sub-mode of the first mode may be configured to produce heat from the main fuel. A second sub-mode of the first mode may be configured to produce heat from the main fuel and the purge gas, thereby combusting the purge gas.

The boiler system may be configured to ignite the support flame by first igniting the pilot flame and then igniting the support flame from the pilot flame, or to ignite the support flame directly from the pilot flame if the pilot flame is maintained, and to supply purge gas to the burner to combust the ammonia in the support flame.

Preferably, each inlet may be controlled 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 first and second sub-modes of the first mode may be possible. The one or more valves may be configured to independently open and close the fuel inlet and 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 oil, and residual fuel. This may include, for example, diesel, marine gas oil (MGO), very low sulfur fuel oil (VLSFO), heavy fuel oil (HFO). The fuel may be a biofuel. It should be noted that other types of fuels may be used as fuels as well, such as ammonia, hydrogen, and methanol. It should be noted that the fuel may include two types of fuel. The two types of fuel may be premixed with each other and supplied from the same fuel source, or kept separate and supplied from two different fuel sources. The fuel source may be, for example, a tank. When the fuel includes two types of fuel and is supplied from two different fuel sources, they may each have one supply line from the respective fuel tank to the burner, but they may be shared. If the two fuels are supplied from two different fuel sources, each with a supply line, they may also each have a fuel inlet, or alternatively there is one fuel inlet connected to two different supply lines so that fuels from the two different fuel sources can be input to the burner through 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 oil and residual fuels. This may include, for example, diesel, marine gas oil (MGO), very low sulfur fuel oil (VLSFO), heavy fuel oil (HFO). The fuel may be a biofuel. It should be noted that other types of fuels, such as ammonia, hydrogen and methanol, may be used as fuels as well.

The apparatus may further comprise an ammonia fuel system, the ammonia fuel system comprising:
an ammonia fuel source for storing ammonia;
A fuel supply system;
an ammonia-fueled engine;
a purge source containing an inert gas and configured to purge ammonia from the 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. Therefore, when the ammonia-fueled engine switches fuels or shuts down, there may be ammonia in the lines that should not be released to the atmosphere or fed back to the ammonia fuel source, as previously described. By flushing the inert gas through those parts of the ammonia fuel system, the ammonia that may be left in the lines is pushed out of the ammonia fuel system to form a mixture of ammonia and inert gas, which may be directed towards the boiler system. The mixture may be directed through an evaporator and/or separator, for example, to take into account that the mixture of ammonia and inert gas may also be a gas-liquid phase mixture. By pushing the ammonia out of the ammonia fuel system with the inert gas, more or less all of the ammonia is provided for to be released from the ammonia fuel system. A safer and more environmentally friendly device is thereby achieved.

The ammonia may be purged from the portion of the ammonia fuel system. Preferably, the ammonia may be purged from the portion close to the engine since it may be dirty ammonia in the portion close to the engine and mixing dirty ammonia back into the ammonia fuel source should be avoided.

Preferably, the ammonia being pushed out of the ammonia fuel system should be able to be pushed out of the system rather than being forced into other parts of the ammonia fuel system. The ammonia fuel system may include one or more valves configured to control the flow of ammonia as it is being pushed out of the ammonia fuel system.

The apparatus may further include a fuel valve train and recirculation to handle ammonia that does not need to be purged. This may be, for example, ammonia that is typically present in a portion of the ammonia fuel system that is relatively close to the fuel tank. Such ammonia typically does not pick up much dirt and water, and may typically be returned to the fuel tank.

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

The apparatus may further comprise an evaporator configured to evaporate the liquid ammonia into gaseous ammonia, thereby providing a gaseous mixture of ammonia and an inert gas to be fed to the burner. It is typically not optimal for the burner for the mixture to include both liquid and gaseous ammonia. Thus, the burner typically requires either liquid or gas, but typically does not function well with a mixture of both. Thus, if the mixture may include both liquid and gas, it may need to be converted to either liquid or gas. By introducing an evaporator into the apparatus, it may be possible to evaporate the liquid ammonia into gaseous ammonia such that the purge fed to the burner may only include the purge gas. Thus, the evaporator may be advantageous in that it provides for only a gaseous purge to be received by the burner. Preferably, the evaporator is arranged such that the purge gas is fed to the evaporator before being fed to the purge gas inlet.

The apparatus 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 to be fed to the burner. By introducing a separator into the apparatus, it may be possible to separate liquid ammonia from gaseous ammonia and inert gas such that the purge fed to the burner may only contain purge gas. The separator may be a gas-liquid separator, typically a drum or tank with a demister at the outlet. The liquid phase of the purge may be connected to the main fuel supply system such that the liquid phase is mixed with the liquid main fuel. It should be noted that the apparatus may comprise either an evaporator or a separator, or only one of them.

The evaporator may be positioned downstream of the separator, for example, so that the purge gas from which most of the liquid phase has been removed in 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 in that more than one fuel may be configured to drive or be burned 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 burn one or more liquid fuels in combination with burning one or more gaseous fuels, where one or more liquid fuels, preferably one liquid fuel at a time, are burned at the same time as one or more gaseous fuels, preferably one gaseous fuel at a time.

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

The apparatus may further comprise a combustion fan configured to provide combustion air to the burner. The combustion fan may be configured to provide a specific amount of combustion air based on pre-set requirements. Preferably, there should be 10-15% more combustion air than fuel in the boiler system. This ratio of combustion air is typically required to have complete combustion of the fuel as well as the purge gas. If the combustion is not complete, it can lead to a dirty furnace and black exhaust gas with a higher carbon oxide CO content than desired.

The apparatus may further include a gas valve train configured to control the flow of purge gas being supplied to the burner from the ammonia fuel system.

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

If the combustion fan is configured to direct the purge gas to the burner, the gas valve train may be omitted from the apparatus. Instead, the combustion fan may be arranged to control and direct the flow of the purge gas being 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 the burner, where it may be combusted in a supporting flame. However, it should be noted that the apparatus may include both a combustion fan and a gas valve train for directing the purge gas. The combustion fan may be designed for the purge gas. A purge gas inlet provided in the combustion fan may ensure optimal mixing with the combustion air. In addition, the combustion fan may be arranged to prevent backflow of the purge gas.

Furthermore, when the apparatus includes an evaporator and/or a separator, the combustion fan is preferably positioned downstream of the evaporator and/or the separator.

The above objects are also achieved by a method for combusting purge gas resulting from an ammonia fuel system fueling an ammonia-fueled engine, the method comprising:
maintaining a support flame in a burner included in the boiler system, the support flame being maintained by fuel provided by a fuel inlet;
intermittently supplying a purge gas, the purge gas being supplied to the burner from an ammonia fuel system by a purge gas inlet, the purge gas comprising a mixture of ammonia and an inert gas;
and combusting the ammonia in a burner with a supporting flame.

The method therefore includes the step of receiving purge gas from the ammonia fuel system into the burner before the ammonia is combusted.

According to the method, the boiler system may be configured to operate in at least one of a first mode and a second mode;
The first mode is a heat production mode in which heat is produced;
The second mode is an ammonia safe purge mode where the boiler is kept warm and ready for high speed operation and/or the pilot flame is maintained.

The further preferred embodiments described above with respect to the apparatus are equally applicable to the method.

The apparatus is preferably located on a ship. The method is preferably carried out on a ship. However, it may be noted that neither the apparatus nor the method is limited to be used on a ship. The apparatus and the method may be useful for other applications where the engine and the boiler are located close to each other. This may be the case, for example, in other marine applications apart from a ship. It may be a platform, such as, for example, a platform of the kind used for drilling for oil or gas. The apparatus and the method may also be useful for land-based applications. The apparatus and the method may be used, for example, for logging or mining applications.

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

The above, as well as additional objects, features and advantages of the present disclosure will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present disclosure, taken in conjunction with the accompanying drawings, in which like reference numerals will be used for similar elements, in which:

FIG. 1 illustrates an apparatus for combusting purge gas resulting from an ammonia-fueled engine. 1 is a flow chart illustrating a method for combusting purge gas resulting from an ammonia-fueled engine.

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

With reference to FIG. 1, an apparatus 100 is disclosed for combusting purge gas resulting from an ammonia fuel system 108 to fuel an ammonia fueled engine 112. The apparatus 100 includes a boiler system 102 and an ammonia fuel system 108. The ammonia fuel system 108 includes an ammonia fueled engine 112.

Purge gas may be generated when the ammonia-fueled engine 112 switches fuel from ammonia to another fuel, either in a controlled manner or as a result of an emergency situation, or when the ammonia-fueled engine 112 shuts down. At this stage, the purge gas is toxic and therefore should not be released to the atmosphere. The purge gas is typically a mixture of ammonia and an inert gas used to purge the 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 be any other inert gas.

The boiler system 102 comprises a burner 104, a fuel inlet 111 and a purge gas inlet 121. The burner 104 is configured to burn the purge gas originating from the ammonia fuel system 108. In other words, the burner 104 is configured to combust the ammonia in the purge gas. The burner 104 may be a multi-fuel burner configured to burn two different fuels, one at a time or simultaneously. The burner 104 may be of the pressure atomized type. The burner 104 may alternatively be of the steam atomized type.

The fuel inlet 111 is configured to supply fuel and thereby maintain a support flame in the burner 104. The fuel inlet 111 is typically configured to supply fuel continuously, at least in the sense that it is capable of maintaining a support flame. Fuel may be supplied initially to provide a pilot flame and may also be supplied as a main fuel when the burner is operating in an operational mode. The main fuel may act as a support flame so that purge gas may be combusted in 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 burner 104. Purge gas may be supplied to the purge gas inlet 121 from the ammonia fuel system 108 via purge gas piping 123. The piping 123 may be double-walled, particularly for the portion of the piping 123 where the purge is in the gas phase.

The fuel inlet 111 may be connected to a fuel source 115, e.g., a fuel tank, via a fuel supply line 113. The fuel source 115 is configured to supply fuel to the burner 104 via the fuel inlet 111. The fuel may be liquefied natural gas (LNG), distillate oil, and residual fuel. This may include, for example, diesel, marine gas oil (MGO), very low sulfur fuel oil (VLSFO), heavy fuel oil (HFO). The fuel may be biofuel. However, it should be noted that the main fuel may be other fuels. The fuel may include one or more types of fuel. If the fuel includes two or more types of fuel, the fuel inlet 111 may be connected to two or more fuel sources. Thus, if the fuel includes two types of fuel, one fuel type may be supplied from the fuel source 115, and the other fuel type may be supplied from another fuel source 135. Typically, the fuels are supplied to the burner 104 exclusively one at a time. Typically, the fuel supply line 113 is operated in that different fuels are provided one at a time, but using the same inlet 111, as illustrated in FIG. 1. One possible combination is to provide liquid fuel to the inlet 111 via the fuel supply line 113 and simultaneously provide gas via a separate gas inlet, such as via the combustion fan 120. The gas provided via the separate gas inlet, such as the combustion fan 120, may be a purge gas and/or it may be a gaseous fuel that does not result from a purge operation.

1 may, if desired, be used to mix two types of fuel in the fuel supply line 113, and the other fuel may be fed to the fuel supply line 113 by another one of the fuel supply lines 133, so that the mixture is fed to the burner 104 via the fuel inlet 111. However, although not illustrated, the two types of fuel may be fed to the burner 104 by two different fuel inlets via two different feed lines. Thus, the apparatus 100 may include an additional feed line arranged separately from the fuel supply line 113, and the additional feed line may be arranged to feed the other fuel to the burner 104 from the other fuel source 135. The other fuel may be any of the fuels listed above with respect to the fuel. Preferably, if the fuel includes two types of fuel, one type may be a liquid fuel and the other type may be a gaseous fuel.

2, a flow chart 200 illustrating a method 200 for combustion of purge gas originating from an ammonia fuel system 108 to fuel an ammonia-fueled engine 112 is shown by way of example. 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 a mode other than the first mode 201 and the second mode 211. The first mode 201 may be a heat production mode in which heat is produced. It may be noted that in this context, the production of heat may refer to the production of steam, heating hot water, heating a thermal fluid, or heating any other medium used in the boiler. The second mode 211 may be an ammonia safe purge mode in which the boiler 106 is warmed and ready for high speed operation and/or a pilot flame may be maintained. The boiler 106 is included in the boiler system 102. In the second mode 211, the boiler may be ready for high speed operation or ready for a high speed 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, a main flame is maintained on the burner 104 for heat production, and no purge gas is supplied to the burner 104. The first sub-mode 201a is configured to produce heat from fuel supplied to the burner 104 by the fuel inlet 111. The second sub-mode 201b of the first mode 201 is configured to produce heat from the main fuel and purge gas, with the purge gas being supplied by the purge gas inlet 121. Thus, in the second sub-mode 201b, a main flame is maintained on the burner 104 for heat production, and purge gas is supplied to the burner 104. Ammonia is combusted with the 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 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 provide purge gas to the burner 104 to combust the ammonia in the support flame.

As such, both the first and second modes are configured to burn ammonia, albeit from 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-fueled engine 112. The ammonia fuel system 108 may include a purge source 165. The ammonia fuel source 155 may be an ammonia tank and is configured to store ammonia before being supplied to the ammonia-fueled engine 112. The fuel supply system 110 is configured to supply ammonia within the ammonia fuel system 108. The ammonia-fueled engine 112 is configured to be powered by ammonia supplied from the ammonia fuel source 155.

The purge source 165 is typically a gas tank containing an inert gas. The inert gas from the purge source 165 is 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. The apparatus 100 may include a gas valve train 118 configured to control the flow of purge gas being supplied from the ammonia fuel system 108 to the burner 104. As described 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. When 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 gas form, and therefore liquid must be removed from the purge gas before being supplied to the burner 104.

The apparatus 100 may include an evaporator 114 configured to evaporate liquid ammonia, if present in the mixture, into gaseous ammonia. By evaporating the liquid ammonia into gaseous ammonia, a gaseous mixture of ammonia and an inert gas may be provided to the burner 104. The evaporator 114 may be disposed in the purge gas piping 123 between the boiler system 102 and the ammonia fuel system 108.

The apparatus 100 may further or alternatively include a separator 116 configured to separate liquid ammonia from gaseous ammonia and inert gas, if present in the mixture. By separating the liquid ammonia from the gaseous ammonia and inert gas, a gaseous mixture of ammonia and inert gas may be provided to the burner 104. The separator 116 may be disposed in the purge gas piping 123 between the boiler system 102 and the ammonia fuel system 108.

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

The apparatus 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 the fuel disposed in the fuel line 133. Thus, the liquid ammonia may be supplied to the burner 104 as a mixture with the fuel.

The apparatus 100 may include a combustion fan 120. The combustion fan 120 may be configured to provide air to the burner 104 for the combustion of ammonia. The combustion fan 120 may be configured to supply a specific amount of air based on a pre-set requirement. The combustion fan 120 may be further or alternatively configured to direct a purge gas to the burner 104. The combustion fan may be further or alternatively configured to direct a purge gas to the burner. The combustion fan 120 may include a purge gas inlet 121, and 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 the purge gas and the combustion air to the burner 104. Those skilled in the art will recognize that the present disclosure is by no means limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

100 Apparatus 102 Boiler system 104 Burner 106 Boiler 108 Ammonia fuel system 110 Fuel supply system 111 Fuel inlet 112 Ammonia fuel engine 113 Fuel supply line 114 Evaporator 115 Fuel source 116 Separator 118 Gas valve train 120 Combustion fan 121 Purge gas inlet 123 Purge gas piping 133 Fuel supply line 135 Fuel source 141 Liquid ammonia inlet 143 Liquid ammonia piping 155 Ammonia fuel source 165 Purge source

Claims (13)

1. An apparatus (100) for combusting purge gas resulting from an ammonia fuel system (108) that fuels an ammonia-fueled engine (112), comprising:
A burner (104),
a fuel inlet (111) configured to supply fuel to thereby maintain a supporting flame for said burner (104);
a boiler system (102) configured to intermittently receive 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; and
An apparatus (100), wherein the burner (104) is configured to combust the ammonia with the supporting flame. the boiler system (102) is configured to operate in at least one of a first mode (201) and a second mode (211);
the first mode (201) is a heat production mode in which heat is produced;
The second mode (211) is an ammonia safe purge mode in which the boiler (106) is warmed and ready for high speed operation and/or a pilot flame is maintained , and the boiler system (102) is
igniting the supporting flame by first igniting a pilot flame and then igniting the supporting flame from the pilot flame, or, if a pilot flame is maintained, igniting the supporting flame directly from the pilot flame; and
The apparatus (100) of claim 1 configured to supply a purge gas to the burner (104) to combust the ammonia with the supporting flame . The apparatus (100) according to claim 2, wherein the boiler system (102) is configured to operate in one of at least a first sub-mode (201a) and a second sub-mode (201b) of the first mode (201), in which in the first sub-mode (201a), a main flame is maintained in the burner (104) for heat production and no purge gas is supplied to the burner (104), and in the second sub-mode (201b), the main flame is maintained in the burner (104) for heat production and purge gas is supplied to the burner (104) to combust the ammonia with the main flame acting as the supporting flame. 4. The apparatus (100) of claim 1, 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 the fuel selected from the group consisting of liquefied natural gas (LNG), distillate oil, and residual fuel. The ammonia fuel system (108) further comprises:
an ammonia fuel source (155) for storing ammonia;
A fuel supply system (110);
the ammonia-fueled engine (112);
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). 6. The apparatus (100) of any one of claims 1 to 5 , wherein the mixture of ammonia and an inert gas comprises gaseous ammonia, liquid ammonia and an inert gas. 7. The apparatus (100) of claim 6, further comprising an evaporator (114) configured to evaporate liquid ammonia into gaseous ammonia, thereby providing a gaseous mixture of ammonia and an inert gas to be supplied to the burner (104). 8. The apparatus (100) of claim 6 or 7, further comprising a separator (116) configured to separate the liquid ammonia from the gaseous ammonia and inert gas, thereby providing a gaseous mixture of ammonia and inert gas to be supplied to the burner (104). The burner (104)
9. The apparatus (100) of any one of claims 1 to 8, which is a multi-fuel burner configured to burn at least two different fuels, one at a time or simultaneously , or to burn one or more liquid fuels in combination with burning one or more gaseous fuels. 10. The apparatus (100) of any one of claims 1 to 9, further comprising a combustion fan (120), the combustion fan (120) comprising the purge gas inlet ( 121 ), the combustion fan (120) configured to mix the purge gas with combustion air and to provide a mixture of the purge gas and combustion air to the burner (104). The apparatus (100) of any one of claims 1 to 10 , wherein the inert gas is nitrogen. 1. A method (200) for combusting purge gas resulting from an ammonia fuel system (108) that fuels an ammonia-fueled engine (112), comprising:
maintaining a support flame in a burner (104) included in the boiler system (102), said support flame being maintained by fuel supplied by a fuel inlet (111);
intermittently supplying the purge gas, the purge gas being 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 in the burner with the supporting flame. the boiler system (102) is configured to operate in at least one of a first mode (201) and a second mode (211);
the first mode (201) is a heat production mode in which heat is produced;
The second mode (211) is an ammonia safe purge mode in which the boiler is warmed and ready for high speed operation and/or a pilot flame is maintained , and the boiler system (102) is
igniting the supporting flame by first igniting a pilot flame and then igniting the supporting flame from the pilot flame, or, if a pilot flame is maintained, igniting the supporting flame directly from the pilot flame; and
The method (200) of claim 12 , further comprising providing a purge gas to the burner (104) to combust the ammonia with the supporting flame .

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