Combustion system, method for purging ammonia gas in combustion system, and method for supplying ammonia gas in combustion system

Abstract

A combustion system 100 comprises: a burner 12; a fuel conduit L1 which is connected to the burner 12, and through which ammonia gas ga is supplied to the burner 12; a fuel valve V2 which is provided in the fuel conduit L1, and which opens and closes the fuel conduit L1; a first gas conduit L3 which is in fluid communication with the fuel conduit L1 between the burner 12 and the fuel valve V2, and through which a first gas g1 inert to the ammonia gas ga is supplied to the fuel conduit L1; and a second gas conduit L4 which is in fluid communication with the fuel conduit L1 between the burner 12 and the fuel valve V2, and through which a second gas g2 inert to the first gas g1 is supplied to the fuel conduit L1.

Description

COMBUSTION SYSTEM, METHOD FOR PURGE OF AMMONIA GAS IN A COMBUSTION SYSTEM, AND METHOD FOR SUPPLYING AMMONIA GAS IN A COMBUSTION SYSTEM - Patent application

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2024-040973, filed on March 15, 2024, the contents of which are incorporated herein by reference.

[0002] In combustion systems such as boilers, ammonia may be used as fuel. For example, Patent Document 1 discloses a power generation facility including a boiler that uses ammonia as fuel. When combustion stops and the boiler is not used for a long period of time, ammonia gas in the ammonia gas fuel piping facility is replaced with nitrogen gas, and the ammonia gas is sent to an ammonia gas absorption unit.

[0003] Patent No. 6319526

[0004] To purge ammonia gas from the piping, a gas inert to ammonia gas, such as nitrogen, is used. Furthermore, to maintain the gas seal on the piping after purging, it is necessary to continue supplying the gas to prevent a pressure drop within the piping. However, using nitrogen for purging, as in Patent Document 1, increases costs.

[0005] The present disclosure aims to provide a combustion system that, when ammonia gas is used as fuel, can maintain gas sealing of piping after purging. The present disclosure also aims to provide a method for purging ammonia gas in a combustion system and a method for supplying ammonia gas in a combustion system.

[0006] A combustion system according to one aspect of the present disclosure includes a burner, a fuel conduit connected to the burner and supplying ammonia gas to the burner, a fuel valve provided in the fuel conduit and opening and closing the fuel conduit, a first gas conduit fluidly connected to the fuel conduit between the burner and the fuel valve and supplying a first gas inert to the ammonia gas to the fuel conduit, and a second gas conduit fluidly connected to the fuel conduit between the burner and the fuel valve and supplying a second gas inert to the first gas to the fuel conduit.

[0007] The first gas may be nitrogen and the second gas may be air.

[0008] The combustion system may include a first gas valve provided in the first gas conduit for opening and closing the first gas conduit, a second gas valve provided in the second gas conduit for opening and closing the second gas conduit, and a control device for controlling the fuel valve, the first gas valve, and the second gas valve, the control device being configured to close the fuel valve to stop the supply of ammonia gas to the burner in order to purge the ammonia gas from the fuel conduit, open the first gas valve to supply the first gas to the fuel conduit, and after supplying the first gas to the fuel conduit, open the second gas valve to supply the second gas to the fuel conduit.

[0009] The control device may be configured to close the second gas valve to stop the supply of the second gas to the fuel conduit to supply ammonia gas to the burner, open the first gas valve to supply the first gas to the fuel conduit, and after supplying the first gas to the fuel conduit, open the fuel valve to supply the ammonia gas to the burner.

[0010] Another aspect of the present disclosure is a method of purging ammonia gas in a combustion system comprising: a burner; a fuel conduit connected to the burner for supplying ammonia gas to the burner; a fuel valve disposed in the fuel conduit for opening and closing the fuel conduit; a first gas conduit in fluid communication with the fuel conduit between the burner and the fuel valve for supplying a first gas inert to the fuel conduit; a second gas conduit in fluid communication with the fuel conduit between the burner and the fuel valve for supplying a second gas inert to the first gas conduit; a first gas valve disposed in the first gas conduit for opening and closing the first gas conduit; and a second gas valve disposed in the second gas conduit for opening and closing the second gas conduit, the method including: closing the fuel valve to stop the supply of ammonia gas to the burner; opening the first gas valve to supply the first gas to the fuel conduit; and, after supplying the first gas to the fuel conduit, opening the second gas valve to supply the second gas to the fuel conduit.

[0011] Yet another aspect of the present disclosure is a method for supplying ammonia gas in a combustion system, the combustion system including: a burner; a fuel conduit connected to the burner for supplying ammonia gas to the burner; a fuel valve disposed in the fuel conduit for opening and closing the fuel conduit; a first gas conduit in fluid communication with the fuel conduit between the burner and the fuel valve for supplying a first gas inert to the fuel conduit; a second gas conduit in fluid communication with the fuel conduit between the burner and the fuel valve for supplying a second gas inert to the first gas conduit; a first gas valve disposed in the first gas conduit for opening and closing the first gas conduit; and a second gas valve disposed in the second gas conduit for opening and closing the second gas conduit, the method including: closing the second gas valve to stop supply of the second gas to the fuel conduit; opening the first gas valve to supply the first gas to the fuel conduit; and, after supplying the first gas to the fuel conduit, opening the fuel valve to supply the ammonia gas to the burner.

[0012] According to the present disclosure, when ammonia is used as fuel, the gas can maintain a seal on the piping after purging.

[0013] 1 is a schematic diagram of a combustion system according to an embodiment; FIG 2 is a flow chart illustrating a method for purging ammonia gas; and FIG 3 is a flow chart illustrating a method for supplying ammonia gas.

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0015] 1 is a schematic diagram of a combustion system 100 according to an embodiment. For example, in this embodiment, the combustion system 100 is applied to a boiler 1 of a thermal power plant. In other embodiments, the combustion system 100 may be applied to other facilities. For example, the combustion system 100 includes the boiler 1 and a control device 90.

[0016] The boiler 1 includes a furnace 11. The furnace 11 defines a combustion space S. In the present disclosure, combustion space means the space in which fuel is combusted.

[0017] The boiler 1 includes at least one burner 12. In this embodiment, the boiler 1 includes a plurality of burners 12. For example, a burner 12 is provided on each of the opposing front and rear walls of the furnace 11. For example, the plurality of burners 12 are arranged in a single row or multiple rows along the horizontal direction.

[0018] The burners 12 inject fuel containing ammonia gas ga into the combustion space S. For example, in the present embodiment, the burners 12 may inject only ammonia gas ga into the combustion space S. Furthermore, for example, in another embodiment, the burners 12 may inject a mixed fuel of ammonia gas ga and another fuel such as a fossil fuel into the combustion space S. Furthermore, for example, in another embodiment, some of the multiple burners 12 may inject ammonia gas ga into the combustion space S, and the rest of the multiple burners 12 may inject another fuel into the combustion space S. Furthermore, the burners 12 may inject only the other fuel into the combustion space S as necessary. The fuel is combusted in the combustion space S.

[0019] The burner 12 is connected to a fuel conduit L1. The fuel conduit L1 supplies ammonia gas ga to the burner 12. For example, the fuel conduit L1 is connected to an ammonia supply source (not shown), such as a tank or an ammonia manufacturing apparatus. For example, the ammonia supply source may be a tank that stores liquid ammonia. In this case, for example, a vaporizer (not shown) may be provided in the fuel conduit L1, and ammonia gas ga may be supplied from the vaporizer to the burner 12. Note that if a portion of the liquid ammonia is not vaporized in the vaporizer, the ammonia gas ga may contain liquid ammonia. The ammonia supply source is not limited to a tank.

[0020] A first fuel valve V1 is provided in the fuel conduit L1. The first fuel valve V1 opens and closes the fuel conduit L1. The first fuel valve V1 is communicatively connected to the control device 90 via wire or wirelessly and is controlled by the control device 90. For example, the first fuel valve V1 may be a ball valve. The first fuel valve V1 is not limited to a ball valve and may include any mechanism that can open and close the fuel conduit L1.

[0021] A second fuel valve V2 is provided in the fuel conduit L1. The second fuel valve V2 is provided in the fuel conduit L1 between the first fuel valve V1 and the burner 12. The second fuel valve V2 is provided in the fuel conduit L1 downstream of the first fuel valve V1. The second fuel valve V2 opens and closes the fuel conduit L1. The second fuel valve V2 is connected to the control device 90 via wire or wireless communication and is controlled by the control device 90. For example, the second fuel valve V2 may be a ball valve. The second fuel valve V2 is not limited to a ball valve and may include any mechanism that can open and close the fuel conduit L1.

[0022] A vent pipe L2 is connected to the fuel conduit L1 between the first fuel valve V1 and the second fuel valve V2. For example, the vent pipe L2 is connected to an ammonia disposal device (not shown), such as a water abatement tank or a flare stack.

[0023] A vent valve V3 is provided in the vent pipe L2. The vent valve V3 opens and closes the vent pipe L2. The vent valve V3 is communicatively connected to the control device 90 via wire or wirelessly and is controlled by the control device 90. For example, in the present embodiment, the second fuel valve V2 and the vent valve V3 may be operated simultaneously by a single driving device. In other embodiments, the second fuel valve V2 and the vent valve V3 may be operated by separate driving devices. For example, the vent valve V3 may be a ball valve. The vent valve V3 is not limited to a ball valve and may include any mechanism capable of opening and closing the vent pipe L2.

[0024] The fuel conduit L1 is in fluid communication with the first gas conduit L3. The first gas conduit L3 supplies the first gas g1 to the fuel conduit L1. The first gas conduit L3 is connected to the fuel conduit L1 at a position downstream of the second fuel valve V2. In this embodiment, the first gas conduit L3 is connected to a junction pipe L5 and is connected to the fuel conduit L1 via the junction pipe L5. In other embodiments, the first gas conduit L3 may be connected directly to the fuel conduit L1.

[0025] The first gas g1 is a gas inert to ammonia. For example, the first gas g1 may be nitrogen. The first gas g1 is not limited to nitrogen. For example, the first gas conduit L3 may be connected to a first gas supply source (not shown), such as a tank or a nitrogen production device. For example, the first gas supply source may be a tank that stores gaseous nitrogen. The first gas supply source is not limited to a tank.

[0026] A first gas valve V4 is provided in the first gas conduit L3. The first gas valve V4 opens and closes the first gas conduit L3. The first gas valve V4 is communicatively connected to the control device 90 via wire or wirelessly and is controlled by the control device 90. For example, the first gas valve V4 may be a ball valve. The first gas valve V4 is not limited to a ball valve and may include any mechanism capable of opening and closing the first gas conduit L3.

[0027] The fuel conduit L1 is in fluid communication with a second gas conduit L4. The second gas conduit L4 supplies a second gas g2 to the fuel conduit L1. The second gas conduit L4 is connected to the fuel conduit L1 at a position downstream of the second fuel valve V2. In this embodiment, the second gas conduit L4 is connected to a junction pipe L5 and is connected to the fuel conduit L1 via the junction pipe L5. In other embodiments, the second gas conduit L4 may be connected directly to the fuel conduit L1.

[0028] The second gas g2 is a gas that is inert with respect to the first gas g1. For example, the second gas g2 may be a gas that is cheaper than the first gas g1. For example, the second gas g2 may be air, specifically, ambient air. The second gas is not limited to air. For example, the second gas conduit L4 may be connected to a second gas supply source such as a compressor (not shown). For example, the compressor may draw in ambient air and send the drawn air to the second gas conduit L4. The second gas supply source is not limited to a compressor.

[0029] A second gas valve V5 is provided in the second gas conduit L4. The second gas valve V5 opens and closes the second gas conduit L4. The second gas valve V5 is communicatively connected to the control device 90 via wire or wirelessly and is controlled by the control device 90. For example, the second gas valve V5 may be a ball valve. The second gas valve V5 is not limited to a ball valve and may include any mechanism capable of opening and closing the second gas conduit L4.

[0030] The fuel conduit L1 may be provided with a pressure sensor Se that measures the pressure inside the fuel conduit L1. The pressure sensor Se is connected to the control device 90 so as to be able to communicate with the control device 90 via wire or wirelessly, and transmits measurement data to the control device 90.

[0031] The control device 90 controls the combustion system 100. The control device 90 includes components such as a processor 90a, a storage device 90b, and a connector 90c, which are connected to each other via a bus. For example, the processor 90a includes a central processing unit (CPU). For example, the storage device 90b includes a hard disk, a read-only memory (ROM) in which programs and the like are stored, and a random access memory (RAM) as a work area. The control device 90 is connected to each component of the combustion system 100 via the connector 90c so as to be able to communicate with them via wired or wireless communication. For example, the control device 90 may further include other components, such as a display device such as a liquid crystal display or a touch panel, and an input device such as a keyboard, buttons, or a touch panel. For example, the operation of the control device 90 may be realized by the processor 90a executing a program stored in the storage device 90b.

[0032] Next, the operation of the combustion system 100 while the ammonia gas ga is being combusted will be described.

[0033] During operation of the boiler 1 (burner 12), the processor 90a opens the first fuel valve V1 and the second fuel valve V2 and closes the vent valve V3, the first gas valve V4, and the second gas valve V5. The fuel conduit L1 supplies ammonia gas ga to the burner 12. The burner 12 injects the ammonia gas ga into the combustion space S, where the ammonia gas ga is combusted. For example, the combustion gas may be used to heat water to steam.

[0034] Next, the operation of the combustion system 100 when the boiler 1 is stopped will be described.

[0035] Fig. 2 is a flowchart showing a method for purging ammonia gas g. For example, the operation shown in Fig. 2 may be started when a command to shut down the boiler 1 is input to the control device 90. Referring to Fig. 1, before the operation shown in Fig. 2, the first fuel valve V1 and the second fuel valve V2 are open, and the vent valve V3, the first gas valve V4, and the second gas valve V5 are closed.

[0036] 2, the processor 90a closes the second fuel valve V2 to stop the supply of ammonia gas ga to the burner 12 (step S100). At the same time, the vent valve V3 is opened in step S100.

[0037] Next, the processor 90a opens the first gas valve V4 to supply the first gas g1 to the fuel conduit L1 (step S102).

[0038] 1, the first gas g1 pushes the ammonia gas ga remaining in the section of the fuel conduit L1 downstream of the second fuel valve V2 into the combustion space S via the burner 12. When the ammonia gas ga is no longer pushed out from the burner 12, combustion stops. Note that the combustion may be stopped by any fire extinguishing means before the operation shown in FIG.

[0039] Referring to FIG. 2, the processor 90a then determines whether or not a predetermined amount or more of the ammonia gas ga in the fuel conduit L1 has been replaced with the first gas g1 (step S104).

[0040] 1 , for example, the length of time required to replace a predetermined amount or more of ammonia gas ga in the fuel conduit L1 with the first gas g1 may be determined in advance by experiment or analysis and stored in the memory device 90b. For example, the predetermined amount of ammonia gas ga may be determined so that the remaining ammonia gas ga does not burn when the second gas g2 is supplied. In step S104, if the elapsed time since the first gas valve V4 was opened exceeds the length of time stored in the memory device 90b, the processor 90a may determine that the ammonia gas ga in the fuel conduit L1 has been replaced with the first gas g1.

[0041] 2, if it is determined in step S104 that the ammonia gas ga in the fuel conduit L1 has not been replaced with the first gas g1 in an amount equal to or greater than the predetermined amount (NO), the processor 90a returns to step S104. For example, step S104 may be repeated at predetermined intervals.

[0042] In step S104, if it is determined that a predetermined amount or more of ammonia gas ga in the fuel pipe L1 has been replaced with the first gas g1 (YES), the processor 90a closes the first gas valve V4 and stops the supply of the first gas g1 to the fuel pipe L1 (step S106).

[0043] Next, the processor 90a opens the second gas valve V5 to supply the second gas g2 to the fuel conduit L1 (S108), and then ends the operation.

[0044] 1 , the second gas g2 pushes the first gas g1 remaining in the section of the fuel conduit L1 downstream of the second fuel valve V2 into the combustion space S via the burner 12. Therefore, the first gas g1 in the fuel conduit L1 is replaced with the second gas g2.

[0045] According to the above operation, ammonia gas ga is purged from the fuel conduit L1. While the boiler 1 is shut down, the second gas conduit L4 continues to supply the second gas g2 to the fuel conduit L1. This seals the burner 12 and the fuel conduit L1, protecting them from unburned fuel and foreign matter from the combustion space S. Furthermore, if the pressure of the ammonia supply source exceeds a predetermined threshold while the boiler 1 is shut down, excess ammonia gas ga is sent to the ammonia treatment device via the vent valve V3 and the vent pipe L2. Note that while the boiler 1 is shut down, the processor 90a may keep the first fuel valve V1 open, or may close the first fuel valve V1 at any time.

[0046] Next, the operation of the combustion system 100 when starting the operation of the boiler 1 will be described.

[0047] Fig. 3 is a flowchart showing a method for supplying ammonia gas g. For example, the operation shown in Fig. 3 may be started when a command to start operation of the boiler 1 is input to the control device 90. With reference to Fig. 1, before the operation shown in Fig. 3, the second fuel valve V2 and the first gas valve V4 are closed, and the vent valve V3 and the second gas valve V5 are open. The first fuel valve V1 may be closed or open.

[0048] Referring to FIG. 3, the processor 90a closes the second gas valve V5 to stop the supply of the second gas g2 to the fuel conduit L1 (step S200).

[0049] Next, the processor 90a opens the first gas valve V4 to supply the first gas g1 to the fuel conduit L1 (step S202).

[0050] Referring to FIG. 1, the first gas g1 pushes out the second gas g2 remaining in the section of the fuel conduit L1 downstream of the second fuel valve V2 into the combustion space S via the burner 12.

[0051] Referring to FIG. 3, the processor 90a then determines whether or not a predetermined amount or more of the second gas g2 in the fuel conduit L1 has been replaced with the first gas g1 (step S204).

[0052] 1 , for example, the length of time required to replace a predetermined amount or more of the second gas g2 in the fuel conduit L1 with the first gas g1 may be determined in advance by experiment or analysis and stored in the memory device 90b. For example, the predetermined amount of the second gas g2 may be determined so that the ammonia gas ga does not burn in the fuel conduit L1 when the ammonia gas ga is supplied. In step S204, if the elapsed time since the first gas valve V4 was opened exceeds the length of time stored in the memory device 90b, the processor 90a may determine that the second gas g2 in the fuel conduit L1 has been replaced with the first gas g1.

[0053] 3, if it is determined in step S204 that the second gas g2 in the fuel conduit L1 has not been replaced with the first gas g1 by a predetermined amount or more (NO), the processor 90a returns to step S204. For example, step S204 may be repeated at predetermined intervals.

[0054] In step S204, if it is determined that a predetermined amount or more of the second gas g2 in the fuel conduit L1 has been replaced with the first gas g1 (YES), the processor 90a closes the first gas valve V4 and stops the supply of the first gas g1 to the fuel conduit L1 (step S206).

[0055] Next, the processor 90a opens the second fuel valve V2 to supply ammonia gas ga to the burner 12 (S208), and ends the operation. Also, in step S208, the vent valve V3 is simultaneously closed. Also, if the first fuel valve V1 is closed, the processor 90a opens the first fuel valve V1 in step S208.

[0056] According to the above operation, ammonia gas ga is supplied to the burner 12. Referring to Fig. 1, the ammonia gas ga injected from the burner 12 into the combustion space S is ignited by an arbitrary ignition device.

[0057] As described above, the combustion system 100 according to this embodiment includes the burner 12, the fuel conduit L1 connected to the burner 12 and supplying ammonia gas ga to the burner 12, the fuel valve V2 provided in the fuel conduit L1 and opening and closing the fuel conduit L1, the first gas conduit L3 fluidly connected to the fuel conduit L1 between the burner 12 and the fuel valve V2 and supplying a first gas g1 inert to the ammonia gas ga to the fuel conduit L1, and the second gas conduit L4 fluidly connected to the fuel conduit L1 between the burner 12 and the fuel valve V2 and supplying a second gas g2 inert to the first gas g1 to the fuel conduit L1. With this configuration, first, the ammonia gas ga remaining in the fuel conduit L1 can be purged with the first gas g1, and then the first gas g1 remaining in the fuel conduit L1 can be purged with the second gas g2. After purging the first gas g1, the burner 12 and the fuel conduit L1 can be sealed by continuing to supply the second gas g2 to the fuel conduit L1. Therefore, when ammonia gas ga is used as fuel, the gas seal of the piping can be maintained even after purging. Furthermore, by using a gas that is less expensive than the first gas g1 as the second gas g2, the cost of sealing can be reduced.

[0058] Furthermore, in the combustion system 100, the first gas g1 is nitrogen and the second gas g2 is air. With this configuration, the second gas g2 can be obtained inexpensively.

[0059] The combustion system 100 also includes a first gas valve V4 provided in the first gas conduit L3 for opening and closing the first gas conduit L3, a second gas valve V5 provided in the second gas conduit L4 for opening and closing the second gas conduit L4, and a control device 90 for controlling the fuel valve V2, the first gas valve V4, and the second gas valve V5. The control device 90 is configured to close the fuel valve V2 to stop the supply of ammonia gas ga to the burner 12 in order to purge the ammonia gas ga from the fuel conduit L1 (step S100), open the first gas valve V4 to supply the first gas g1 to the fuel conduit L1 (step S102), and, after supplying the first gas g1 to the fuel conduit L1, open the second gas valve V5 to supply the second gas g2 to the fuel conduit L1 (step S108). With this configuration, purging and sealing can be automatically performed by the control device 90 when the operation of the burner 12 is stopped.

[0060] Furthermore, in the combustion system 100, the control device 90 is configured to execute the following steps in order to supply ammonia gas ga to the burner 12: close the second gas valve V5 to stop the supply of the second gas g2 to the fuel conduit L1 (step S200), open the first gas valve V4 to supply the first gas g1 to the fuel conduit L1 (step S202), and, after supplying the first gas g1 to the fuel conduit L1, open the fuel valve V2 to supply ammonia gas ga to the burner 12 (step S208). With this configuration, when starting operation of the burner 12, the control device 90 can automatically release the seal and supply ammonia gas ga.

[0061] Furthermore, a method for purging ammonia gas ga in the combustion system 100 according to this embodiment includes closing the fuel valve V2 to stop the supply of ammonia gas ga to the burner 12 (step S100), opening the first gas valve V4 to supply the first gas g1 to the fuel conduit L1 (step S102), and, after supplying the first gas g1 to the fuel conduit L1, opening the second gas valve V5 to supply the second gas g2 to the fuel conduit L1 (step S108). With this configuration, purging and sealing can be performed when the operation of the burner 12 is stopped.

[0062] Furthermore, the method for supplying ammonia gas ga in the combustion system 100 according to this embodiment includes closing the second gas valve V5 to stop the supply of the second gas g2 to the fuel conduit L1 (step S200), opening the first gas valve V4 to supply the first gas g1 to the fuel conduit L1 (step S202), and, after supplying the first gas g1 to the fuel conduit L1, opening the fuel valve V2 to supply ammonia gas ga to the burner 12 (step S208). With this configuration, in addition to performing purging and sealing when the operation of the burner 12 is stopped, it is possible to release the seal and supply ammonia gas ga when the operation of the burner 12 is started.

[0063] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to the above embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also fall within the technical scope of the present disclosure. Furthermore, the steps of the method of the above embodiments do not have to be performed in the order described above, and may be performed in a different order as long as no technical contradiction occurs.

[0064] For example, referring to Figure 2, in the above embodiment, step S102 is started after step S100. In other embodiments, for example, step S102 may be started simultaneously with step S100.

[0065] Similarly, in the above embodiment, step S108 is started after step S106. In other embodiments, for example, step S108 may be started simultaneously with step S106.

[0066] 3, in the above embodiment, step S202 is started after step S200. In other embodiments, for example, step S202 may be started simultaneously with step S200.

[0067] Similarly, in the above embodiment, step S208 is started after step S206. In other embodiments, for example, step S208 may be started simultaneously with step S206.

[0068] The present disclosure provides ２ It can promote the use of ammonia, which leads to reduced emissions, thereby contributing, for example, to Sustainable Development Goal (SDG) 7 "Ensure access to affordable, reliable, sustainable and modern energy" and SDG 13 "Take urgent action to combat climate change and its impacts".

[0069] 12 Burner 90 Control device 100 Combustion system g1 First gas g2 Second gas ga Ammonia gas L1 Fuel conduit L3 First gas conduit L4 Second gas conduit V2 Second fuel valve (fuel valve) V4 First gas valve V5 Second gas valve

Claims

1. A combustion system comprising: a burner; a fuel conduit connected to the burner and supplying ammonia gas to the burner; a fuel valve provided in the fuel conduit and opening and closing the fuel conduit; a first gas conduit fluidly communicating with the fuel conduit between the burner and the fuel valve and supplying a first gas inert to the ammonia gas to the fuel conduit; and a second gas conduit fluidly communicating with the fuel conduit between the burner and the fuel valve and supplying a second gas inert to the first gas to the fuel conduit.

2. The combustion system of claim 1, wherein said first gas is nitrogen and said second gas is air.

3. The combustion system according to claim 1 or 2, comprising: a first gas valve provided in the first gas conduit for opening and closing the first gas conduit; a second gas valve provided in the second gas conduit for opening and closing the second gas conduit; and a control device for controlling the fuel valve, the first gas valve, and the second gas valve, the control device being configured to perform the following operations in order to purge ammonia gas from the fuel conduit: close the fuel valve to stop the supply of ammonia gas to the burner; open the first gas valve to supply the first gas to the fuel conduit; and after supplying the first gas to the fuel conduit, open the second gas valve to supply the second gas to the fuel conduit.

4. The combustion system according to claim 1 or 2, comprising: a first gas valve provided in the first gas conduit for opening and closing the first gas conduit; a second gas valve provided in the second gas conduit for opening and closing the second gas conduit; and a control device for controlling the fuel valve, the first gas valve, and the second gas valve, the control device being configured to perform the following operations in order to supply ammonia gas to the burner: close the second gas valve to stop the supply of the second gas to the fuel conduit; open the first gas valve to supply the first gas to the fuel conduit; and after supplying the first gas to the fuel conduit, open the fuel valve to supply the ammonia gas to the burner.

5. The combustion system according to claim 3, wherein the control device is configured to execute the following operations in order to supply ammonia gas to the burner: close the second gas valve to stop the supply of the second gas to the fuel conduit; open the first gas valve to supply the first gas to the fuel conduit; and after supplying the first gas to the fuel conduit, open the fuel valve to supply ammonia gas to the burner.

6. A method for purging ammonia gas in a combustion system, the combustion system comprising: a burner; a fuel conduit connected to the burner and supplying ammonia gas to the burner; a fuel valve provided in the fuel conduit and opening and closing the fuel conduit; a first gas conduit fluidly communicating with the fuel conduit between the burner and the fuel valve and supplying a first gas inert to the fuel conduit; a second gas conduit fluidly communicating with the fuel conduit between the burner and the fuel valve and supplying a second gas inert to the first gas conduit; a first gas valve provided in the first gas conduit and opening and closing the first gas conduit; and a second gas valve provided in the second gas conduit and opening and closing the second gas conduit, the method comprising: closing the fuel valve to stop the supply of ammonia gas to the burner; opening the first gas valve to supply the first gas to the fuel conduit; after supplying the first gas to the fuel conduit, opening the second gas valve to supply the second gas to the fuel conduit.

7. A method for supplying ammonia gas in a combustion system, the combustion system comprising: a burner; a fuel conduit connected to the burner for supplying ammonia gas to the burner; a fuel valve provided in the fuel conduit for opening and closing the fuel conduit; a first gas conduit in fluid communication with the fuel conduit between the burner and the fuel valve for supplying a first gas inert to the fuel conduit; a second gas conduit in fluid communication with the fuel conduit between the burner and the fuel valve for supplying a second gas inert to the first gas conduit; a first gas valve provided in the first gas conduit for opening and closing the first gas conduit; and a second gas valve provided in the second gas conduit for opening and closing the second gas conduit, the method comprising: closing the second gas valve to stop the supply of the second gas to the fuel conduit; opening the first gas valve to supply the first gas to the fuel conduit; after supplying the first gas to the fuel conduit, opening the fuel valve to supply ammonia gas to the burner.

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