Boilers, boiler systems

Abstract

The present invention provides a boiler that can quickly detect abnormalities or malfunctions in the abatement equipment and safely shut down without causing ammonia leakage that would adversely affect the surrounding environment or human health, as well as a boiler system that can suppress ammonia leakage even when the boiler is shut down in an emergency. [Solution] The boiler is used in a boiler system that includes a boiler that burns ammonia fuel or a first fuel and ammonia fuel, a pollution control device, and an exhaust gas line, and includes an exhaust gas pressure detection unit and a control unit. The control unit includes an exhaust gas pressure storage unit that stores a first pressure value and a second pressure value, which are criteria for determining abnormalities on the high pressure side and low pressure side of the exhaust gas pressure, and a first operation stop control associated with these, which stops the operation of the boiler after burning only the first fuel, and the control unit performs the first operation stop control when the exhaust gas pressure becomes equal to or greater than the first pressure value or less than or equal to the second pressure value.

Description

Technical Field

[0001] The present invention relates to a boiler that uses ammonia as fuel and a boiler system including the same.

Background Art

[0002] Conventionally, hydrocarbon fuels such as natural gas and oil fuel have been used in boilers and the like. However, in recent years, in order to reduce carbon dioxide emissions, a part of the hydrocarbon fuel has been replaced with ammonia that does not generate carbon dioxide, and various boilers that use ammonia as fuel, such as boilers that co-fire hydrocarbon fuel and ammonia, and boilers that burn only ammonia, have been developed (see, for example, Patent Document 1). When burning ammonia, depending on the combustion state of the boiler and the like, ammonia may be contained in the exhaust gas. Even at a low concentration, leakage of ammonia raises concerns about adverse effects on the surrounding environment and the human body. Therefore, a boiler system including a decontamination device for removing residual ammonia in the exhaust gas so that ammonia is not released into the atmosphere is also widely known (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] On the other hand, when the operation is stopped due to an abnormality in the decontamination device, or when a flow path blockage or the like occurs due to a malfunction of a damper or the like provided in the exhaust gas flow path to the decontamination device, the exhaust gas from the boiler has nowhere to go, and there is a risk of ammonia leakage due to combustion problems caused by an increase in furnace pressure and exhaust gas leakage from the exhaust gas line. Furthermore, if exhaust gas is drawn in at a volume exceeding the intended level due to a malfunction in the control of the induced draft fan installed in the pollution control device, the pressure in the exhaust gas flow path may drop, causing the boiler furnace pressure to decrease and potentially leading to a fire.

[0005] During a normal boiler shutdown, the boiler's control unit shuts off the ammonia supply, performs an air purge of the furnace and other areas with combustion air, and purges any remaining ammonia in the ammonia supply line piping with purge gas before stopping operation. At this time, a fuel other than ammonia fuel, such as city gas, may be burned to burn the ammonia contained in the purge gas. However, if the boiler is shut down in an emergency due to the abnormalities or malfunctions described above, it may not be possible to perform a normal shutdown.

[0006] The present invention has been made in view of the above problems, and aims to provide a boiler that can quickly detect abnormalities or malfunctions on the pollution control device side and safely shut down without causing ammonia leakage that would adversely affect the surrounding environment or human health, and a boiler system that can suppress ammonia leakage even when the boiler is shut down in an emergency. [Means for solving the problem]

[0007] The present invention solves the above problem by the following means.

[0008] The boiler of the present invention is a boiler used in a boiler system comprising: a boiler that burns ammonia fuel containing ammonia, or a boiler that burns a first fuel having a faster combustion rate than the ammonia fuel and the ammonia fuel; a pollution control device that removes ammonia contained in the exhaust gas discharged from the boiler; and an exhaust gas line that flows the exhaust gas from the boiler to the pollution control device, wherein the boiler comprises a boiler body that recovers heat from combustion gas produced by combustion; an exhaust gas pressure detection unit that detects the exhaust gas pressure in the exhaust gas line; and a control unit that controls the operation of the boiler, the control unit comprising an exhaust gas pressure storage unit, and the exhaust gas pressure storage unit, The control unit stores a first pressure value which is a criterion for determining an abnormality on the high-pressure side of the exhaust gas pressure, a second pressure value which is a criterion for determining an abnormality on the low-pressure side of the exhaust gas pressure and is smaller than the first pressure value, and a first operation stop control which is associated with the first pressure value and the second pressure value and stops the operation of the boiler after burning only the first fuel. The control unit performs the first operation stop control in at least one of the following cases: when the detection result of the exhaust gas pressure detection unit is greater than or equal to the first pressure value read from the exhaust gas pressure storage unit, or when the detection result of the exhaust gas pressure detection unit is less than or equal to the second pressure value read from the exhaust gas pressure storage unit.

[0009] Furthermore, the exhaust gas pressure storage unit stores a third pressure value which is a criterion for determining an abnormality on the high-pressure side of the exhaust gas pressure and is greater than the first pressure value, a fourth pressure value which is a criterion for determining an abnormality on the low-pressure side of the exhaust gas pressure and is less than the second pressure value, and a second operation stop control which is associated with the third pressure value and the fourth pressure value and immediately stops the operation of the boiler. The control unit preferably performs the second operation stop control in at least one of the following cases: when the exhaust gas pressure rises and the detection result of the exhaust gas pressure detection unit becomes greater than or equal to the third pressure value read from the exhaust gas pressure storage unit, or when the exhaust gas pressure falls and the detection result of the exhaust gas pressure detection unit becomes less than or equal to the fourth pressure value read from the exhaust gas pressure storage unit.

[0010] The boiler system of the present invention comprises the above-mentioned boiler, a decontamination device for removing ammonia contained in the exhaust gas, and an exhaust gas line for circulating the exhaust gas from the boiler to the decontamination device.

[0011] The boiler system of the present invention comprises the above-mentioned boiler, a decontamination device for removing ammonia contained in the exhaust gas discharged from the boiler, and an exhaust gas line for circulating the exhaust gas from the boiler to the decontamination device, wherein the boiler system control unit controls the operation of the boiler system, and a washing unit removes ammonia from the exhaust gas by washing, the exhaust gas line comprises a branch exhaust gas line that branches off from the exhaust gas line and through which at least a portion of the exhaust gas flows, and a flow control unit provided in the branch exhaust gas line The boiler system control unit comprises an opening / closing section that can open and close a passage, the washing section is provided upstream of the branching section of the branch exhaust gas line from the exhaust gas line, and the boiler system control unit opens the opening / closing section and discharges the exhaust gas washed by the washing section from the branch exhaust gas line when the detection result of the exhaust gas pressure detection section is equal to or greater than the third pressure value read from the exhaust gas pressure storage section, or when the detection result of the exhaust gas pressure detection section is equal to or less than the fourth pressure value read from the exhaust gas pressure storage section. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a boiler that can quickly detect abnormalities or malfunctions on the abatement device side and safely shut down without causing ammonia leakage that would adversely affect the surrounding environment or human health, and a boiler system that can suppress ammonia leakage even when the boiler is shut down in an emergency. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram illustrating a boiler and boiler system according to the first embodiment. [Figure 2] This table shows an example of the first to fourth pressure values ​​T4 of the exhaust gas in the first embodiment. [Figure 3] This is a diagram illustrating a boiler and boiler system according to a second embodiment. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below with reference to the drawings and other figures. Note that the following figures, including Figure 1, are schematic representations, and the size and shape of each part have been exaggerated as appropriate for ease of understanding.

[0015] (First Embodiment) Figure 1 is a diagram illustrating the boiler 10 and boiler system 1 of the first embodiment. The boiler 10 of this embodiment is an ammonia co-firing boiler that burns ammonia fuel (ammonia) F2 and a first fuel F1, which burns faster than ammonia, in a burner 12. In addition to simultaneous combustion of ammonia fuel F2 and the first fuel F1, the boiler of this embodiment may also be a boiler capable of burning only ammonia fuel F2 (ammonia-only combustion). Furthermore, the boiler 10 in this embodiment is a steam boiler that burns ammonia fuel F2 and first fuel F1 to heat water and generate steam, and supplies steam to load equipment (not shown).

[0016] In this embodiment, ammonia fuel F2 is described as ammonia, but it is not limited to ammonia. Any fuel in which ammonia (NH3) accounts for 20% or more of the volume concentration of the components constituting the gaseous fuel may be used. Furthermore, in this specification, "ammonia contained in exhaust gas" refers to unburned ammonia contained in exhaust gas E1 when ammonia fuel F2 does not burn completely, and ammonia remaining in the piping of the ammonia fuel supply line L200 etc. which is mixed into exhaust gas E1 after the boiler has stopped burning.

[0017] The boiler 10 includes a boiler body 11, a burner 12, an economizer 55, an exhaust gas pressure sensor 41, a first fuel supply line L100, an ammonia fuel supply line L200, an air supply line L300, a feed water line L500, a purge gas supply line L600, a steam supply line (not shown), a control unit 70 for controlling the operation of the boiler 10, and the like. Further, the boiler system 1 includes this boiler 10, an exhaust gas line L400 through which the exhaust gas E1 discharged from the boiler 10 flows, and a decontamination device 80. In this specification, the "line" is a general term for a flow path, a route, a pipeline, and the like.

[0018] The boiler body 11 includes a lower header, a plurality of water pipes, an upper header, a combustion space (all not shown), and the like. The boiler body 11 recovers heat from the combustion gas generated by burning fuel in the combustion space, and heats the water (feed water W1) supplied from the feed water line L500 to the boiler body 11 to generate steam. The burner 12 is disposed above the boiler body 11. The first fuel supply line L100 and the ammonia fuel supply line L200 are connected to the burner 12. Further, the air supply line L300 is connected to the wind box 13 to supply combustion air A1 to the burner 12. The burner 12 ejects the first fuel F1 and the ammonia fuel F2, and burns the first fuel F1 and the ammonia fuel F2 in the combustion space of the boiler body 11. In the present embodiment, first, the first fuel F1 and the combustion air A1 are supplied to the burner 12 to start combustion. Next, the ammonia fuel F2 is supplied to the combustion part of the first fuel F1, and a predetermined amount of combustion air A1 corresponding to the total amount of the first fuel F1 and the ammonia fuel F2 is supplied to the burner 12. Thereby, the boiler 10 starts co-combustion of the ammonia fuel F2 and the first fuel F1.

[0019] The first fuel supply line L100 supplies the first fuel F1 from a supply source (not shown) of the first fuel F1 to the burner 12. The first fuel supply line L100 includes shut-off valves V11, V13 and a flow rate adjustment valve V12. The shut-off valves V11 and V13 are constituted by solenoid valves, open and close the flow path of the first fuel supply line L100, and supply or stop the supply of the first fuel F1. The shut-off valves V11 and V13 are electrically connected to the control unit 70 and are controlled by signals transmitted from the control unit 70. In the present embodiment, in the first fuel supply line L100, the shut-off valve V11 is arranged on the upstream side of the shut-off valve V13.

[0020] The flow rate adjustment valve V12 is an adjustment valve that adjusts the flow rate of the first fuel F1 by adjusting the opening degree of the valve. The flow rate adjustment valve V12 is electrically connected to the control unit 70, and the control unit 70 transmits a signal for controlling the opening degree to the flow rate adjustment valve V12 according to the required combustion amount. In the present embodiment, in the first fuel supply line L100, the flow rate adjustment valve V12 is arranged between the shut-off valve V11 and the shut-off valve V13.

[0021] The first fuel F1 is a fuel with a combustion rate faster than ammonia. The first fuel F1 may use liquid fuel or gaseous fuel. As the liquid fuel, oil fuel, alcohol fuel, etc. can be used as the first fuel. As the gaseous fuel, hydrogen-based fuel gas including hydrogen gas and mixed gas containing hydrogen, liquefied natural gas (hereinafter referred to as LNG), liquefied petroleum gas (LPG), hydrocarbon gas such as city gas (13A), etc. can be used. In the present embodiment, as an example, an example of using city gas (13A) as the first fuel F1 will be described.

[0022] The ammonia fuel supply line L200 supplies the ammonia fuel F2 from a supply source (not shown) of the ammonia fuel F2 to the burner 12. The ammonia fuel supply line L200 includes shut-off valves V21 and V23 and a flow rate adjustment valve V22. The shut-off valves V21 and V23 are constituted by solenoid valves, open and close the flow path of the ammonia fuel supply line L200, and supply or stop the supply of the ammonia fuel F2. The shut-off valves V21 and V23 are electrically connected to the control unit 70 and are controlled by signals transmitted from the control unit 70. In the present embodiment, in the ammonia fuel supply line L200, the shut-off valve V21 is arranged on the upstream side of the shut-off valve V23.

[0023] The flow control valve V22 is a control valve that adjusts the flow rate of ammonia fuel F2 by adjusting the opening degree of the valve. The flow control valve V22 is electrically connected to the control unit 70, and the control unit 70 transmits a signal to the flow control valve V22 to control the opening degree according to the required combustion amount. In this embodiment, the flow control valve V22 is located in the ammonia fuel supply line L200 between shut-off valve V21 and shut-off valve V23. In this embodiment, the ammonia fuel F2 is ammonia gas, as described above.

[0024] The purge gas supply line L600 supplies purge gas G1 from a purge gas supply source (not shown) to the ammonia fuel supply line L200. The upstream side of the purge gas supply line L600 is connected to the purge gas supply source, and the downstream side of the purge gas supply line L600 is connected to the downstream side of the shut-off valve V23 of the ammonia fuel supply line L200 and in the vicinity of the shut-off valve V23. The purge gas supply line L600 is equipped with shut-off valves V61, V62, etc.

[0025] The shut-off valves V61 and V62 are composed of solenoid valves and open and close the flow path of the purge gas supply line L600 to supply or stop the purge gas G1. The shut-off valves V61 and V62 are electrically connected to the control unit 70 and are controlled by signals transmitted from the control unit 70. The purge gas supply line L600 is further equipped with a flow sensor and an orifice (not shown). The flow sensor is a detection unit that detects the flow rate of the purge gas G1. The flow sensor is electrically connected to the control unit 70, which can acquire the detection result of the flow sensor. As the purge gas G1, gases such as nitrogen, helium, and neon, hydrocarbon gases such as methane, and city gas can be used. In this embodiment, an example in which nitrogen is used as the purge gas G1 will be explained.

[0026] The air supply line L300 supplies combustion air A1 to the burner 12. The upstream end of the air supply line L300 is connected to the blower 31, and the downstream end of the air supply line L300 is connected to the wind box 13. The air supply line L300 comprises the blower 31 and the damper 33, from upstream to downstream. The blower 31 supplies combustion air A1 to the burner 12. The blower 31 comprises a fan and a motor that rotates the fan, and the rotation speed of the motor can be adjusted by controlling the frequency with an inverter 32. Therefore, the amount of combustion air A1 supplied to the burner 12 can be adjusted by controlling the frequency of the inverter 32. The inverter 32 is electrically connected to the control unit 70 and is controlled by signals transmitted from the control unit 70.

[0027] The damper 33 adjusts the amount of combustion air A1 supplied to the burner 12 by adjusting the damper's opening. Specifically, the damper 33 is rotatably positioned between a closed state, which blocks the flow path of the air supply line L300, and an open state, which rotates from this closed state to a predetermined angle (e.g., 90 degrees) to open the flow path of the air supply line L300. The damper 33 is electrically connected to the control unit 70 and controlled by signals transmitted from the control unit 70.

[0028] The combustion gas generated by the combustion of at least one of the first fuel F1 and ammonia fuel F2 is heat-exchanged in the boiler 11 and then further heat-exchanged in the economizer 55 before flowing through the exhaust gas line L400 as exhaust gas E1. The upstream side of the exhaust gas line L400 is connected to the economizer 55, and the downstream side of the exhaust gas line L400 is connected to the damper 42 of the pollution control device 80. The economizer 55 is a heat exchanger that exchanges heat between the combustion gas, which has undergone heat exchange in the boiler 11, and the feedwater W1. The feedwater W1 heated in the economizer 55 is supplied to the lower header (not shown) of the boiler 11, where it is heated by the combustion gas and turned into steam.

[0029] An exhaust gas pressure sensor 41, which is an exhaust gas pressure detection unit for detecting the exhaust gas pressure of the exhaust gas line L400, is provided at the exhaust gas outlet of the economizer 55. The exhaust gas pressure sensor 41 is electrically connected to the control unit 70, and the detection result of the exhaust gas pressure sensor 41 can be obtained by the control unit 70. Note that the exhaust gas pressure sensor 41 may be installed at a location other than the location shown in Figure 1, as long as the exhaust gas pressure can be detected, for example, it may be installed in the exhaust gas line L400.

[0030] The water supply line L500 supplies water W1 from a water source (not shown) to the boiler 10. The upstream side of the water supply line L500 is connected to the water source (not shown), and the downstream side is connected to the economizer 55. The water supply line L500 is equipped with a pump 51, shut-off valves V52 and V53, and a flow control valve V54.

[0031] Pump 51 adjusts the amount of water supplied to the water supply W1. Note that, in addition to pump 51, a flow control valve or similar device capable of adjusting the flow rate of the water supply W1 may also be provided. The shut-off valves V52 and V53 are composed of solenoid valves and open and close the flow path of the water supply line L500 to supply or stop the water supply W1. The shut-off valves V52 and V53 are electrically connected to the control unit 70 and are controlled by signals transmitted from the control unit 70. The flow control valve V54 is a control valve that adjusts the flow rate of the water supply W1 by adjusting the valve opening. The flow control valve V54 is electrically connected to the control unit 70, and the control unit 70 sends a signal to the flow control valve V54 to control its opening according to the required combustion rate. In this embodiment, the boiler 10 and boiler system 1 will be described using an example where the feedwater to the boiler 10 is a continuous feedwater supply that continuously supplies an amount of water that has been converted into steam according to the amount of combustion.

[0032] The control unit 70 controls various operations, such as the operation of the boiler 10. As shown in Figure 1, the control unit 70 includes a storage unit 71. The control unit 70 is composed of an arithmetic processor such as a PLC (Programmable Logic Controller), a DSP (Digital Signal Processor), or an FPGA (Field-Programmable Gate Array). The various functions of the control unit 70 are realized, for example, by executing predetermined software (programs) stored in the memory unit 71. The various functions of the control unit 70 may be realized through the cooperation of hardware and software, or they may be realized by hardware (electronic circuits) alone.

[0033] The memory unit 71 stores various setting information. The memory unit 71 also includes an exhaust gas pressure memory unit 72. The exhaust gas pressure memory unit 72 stores a first pressure value T1, which is a criterion for determining abnormalities on the high-pressure side of the exhaust gas pressure; a second pressure value T2, which is a criterion for determining abnormalities on the low-pressure side of the exhaust gas pressure and is smaller than the first pressure value T1; and a first operation stop control associated with the first pressure value T1 and the second pressure value T2. Furthermore, the exhaust gas pressure memory unit 72 stores a third pressure value T3 which is greater than the first pressure value T1 and serves as a criterion for determining abnormalities on the high-pressure side of the exhaust gas pressure, a fourth pressure value T4 which is less than the second pressure value T2 and serves as a criterion for determining abnormalities on the low-pressure side of the exhaust gas pressure, and a second operation stop control associated with the third pressure value T3 and the fourth pressure value T4.

[0034] The control unit 70 performs a first operation stop control to stop the operation of the boiler 10 when the detection result of the exhaust gas pressure sensor 41, which is the exhaust gas pressure detection unit, becomes equal to or greater than the first pressure value T1 read from the exhaust gas pressure storage unit 72, and when the detection result of the exhaust gas pressure sensor 41 becomes equal to or less than the second pressure value T2 read from the exhaust gas pressure storage unit. The first shutdown control is performed by stopping the boiler 10 in the normal shutdown process. In the first shutdown control, the control unit 70 first stops the supply of ammonia fuel F2 to the burner 12 and supplies purge gas G1 to the ammonia fuel supply line L200. At this time, the control unit 70 supplies the first fuel F1 to the burner 12 and the combustion air A1 to the burner 12, and continues to burn only the first fuel F1 for a predetermined time. When burning only the first fuel F1, the control unit 70 adjusts the frequency of the inverter 32 and the opening of the damper 33 so that the flow rate of the combustion air A1 is matched to the lowest combustion rate (minimum combustion rate).

[0035] Here, the control unit 70 performs a first operation stop control to improve safety when the detection result of the exhaust gas pressure sensor 41 becomes greater than or equal to a first pressure value T1, or when it becomes less than or equal to a second pressure value T2. However, the first operation stop control may be performed in either the case where the pressure becomes greater than or equal to the first pressure value T1, or when it becomes less than or equal to the second pressure value T2. For example, in a state where ammonia in the exhaust gas E1 can be removed by the abatement device 80, if the detection result of the exhaust gas pressure sensor 41 is less than or equal to the second pressure value T2, the control unit 70 may not perform the first operation stop control when the pressure is less than or equal to the second pressure value T2.

[0036] In the first shutdown control of the boiler 10, the control unit 70 closes the shut-off valves V21 and V23 of the ammonia fuel supply line L200 to stop the supply of ammonia fuel F2. The control unit 70 also opens the shut-off valves V61 and V62 of the purge gas supply line L600 to start supplying purge gas G1 to the ammonia fuel supply line L200 and purges the piping of the ammonia fuel supply line L200. The control unit 70 also continues to supply the first fuel F1 to the burner 12, controls the frequency of the inverter 32, and supplies combustion air A1 necessary for the combustion of the first fuel F1 from the air supply line L300 using the blower 31.

[0037] As a result, the control unit 70 injects the first fuel F1 and combustion air A1 from the burner 12 for a predetermined time, burning only the first fuel F1. At this time, the ammonia fuel F2 remaining in the ammonia fuel supply line L200 is discharged to the burner 12 by pipe purging and is burned by the combustion of the first fuel F1. After burning only the first fuel F1 for a predetermined time and burning off the ammonia fuel F2 remaining in the pipe, the control unit 70 stops supplying the first fuel F1 to the burner 12 and stops the operation of the blower 31. The control unit 70 may simultaneously stop the supply of ammonia fuel F2 and start the supply of purge gas G1, or it may start supplying purge gas G1 after stopping the supply of ammonia fuel F2.

[0038] Furthermore, the control unit 70 performs a second operation stop control to stop the operation of the boiler 10 when the exhaust gas pressure rises and the detection result of the exhaust gas pressure sensor 41, which is the exhaust gas pressure detection unit, becomes equal to or greater than the third pressure value T3 read from the exhaust gas pressure storage unit 72, and when the exhaust gas pressure falls and the detection result of the exhaust gas pressure sensor 41 becomes equal to or less than the fourth pressure value T4 read from the exhaust gas pressure storage unit 72. The second shutdown control immediately stops the operation of the boiler 10. In the second shutdown control, the control unit 70 stops the supply of ammonia fuel F2 and first fuel F1 to the burner 12, stops the supply of combustion air A1, and immediately stops the operation of the boiler 10.

[0039] Here, the control unit 70 performs a second operation stop control when the detection result of the exhaust gas pressure sensor 41 is above the third pressure value T3 or below the fourth pressure value T4, thereby improving safety during shutdown. However, the control unit 70 may perform the second operation stop control when the detection result of the exhaust gas pressure sensor 41 is above the third pressure value T3 or below, or when the detection result is below the fourth pressure value T4. For example, if the boiler 10 is equipped with a furnace pressure detection unit (not shown) and control is performed to emergency stop the boiler 10 when the furnace pressure drops below a predetermined pressure, it is possible not to perform the second operation stop control when the fourth pressure value T4 or below is not shown.

[0040] In the second operation shutdown control of the boiler 10, the control unit 70 closes the shut-off valves V21 and V23 of the ammonia fuel supply line L200 to stop the supply of ammonia fuel F2 to the burner 12. The control unit 70 also closes the shut-off valves V11 and V13 of the first fuel supply line L100 to stop the supply of the first fuel F1 to the burner 12. Furthermore, the control unit 70 stops the operation of the blower 31 to stop the supply of combustion air A1 to the burner 12. Note that in the second operation shutdown control, the control unit 70 does not purge the ammonia fuel supply line L200 or burn only the first fuel F1. In this embodiment, as an example, the control unit 70 will be described in which it simultaneously stops the supply of ammonia fuel F2, the supply of first fuel F1, and the supply of combustion air A1.

[0041] The boiler system 1 comprises a boiler 10, an exhaust gas line L400, and a pollution control device 80. The exhaust gas line L400 is connected to the boiler's economizer 55 on its upstream side and to the damper 42 of the pollution control device 80 on its downstream side. The exhaust gas line L400 introduces the exhaust gas E1 discharged from the boiler 10 into the pollution control device 80.

[0042] The abatement device 80 is a device that abates ammonia in the exhaust gas E1, and removes ammonia by dissolving it through methods such as water spraying. The abatement device 80 comprises a damper 42, an induced draft fan 44, and an abatement device control unit (not shown). The exhaust gas E1 from which ammonia has been removed by the abatement device 80 is discharged out of the system from a second exhaust gas line L430 located downstream of the abatement device 80.

[0043] The damper 42 adjusts the flow rate of exhaust gas E1 discharged to the pollution control device 80. The damper 42 is rotatably positioned to operate between a closed state, which blocks the flow path of the exhaust gas line L400, and an open state, which rotates from this closed state to a predetermined angle (e.g., 90 degrees) to open the flow path of the exhaust gas line L400. The damper 42 is electrically connected to a pollution control device control unit (not shown), which will be described later, and is controlled by signals transmitted from the control unit 70.

[0044] The induced draft fan 44 is installed in the exhaust gas line L400 and is a fan capable of drawing exhaust gas E1 into the abatement device 80. The induced draft fan 44 is electrically connected to the abatement device control unit, and the rotation speed of the induced draft fan 44 (amount of exhaust gas E1 drawn in) is controlled by a signal transmitted from the abatement device control unit. The rotation speed of the induced draft fan 44 is controlled by the abatement device control unit so that the pressure of an exhaust gas pressure sensor (not shown) installed at the inlet (near the upstream side) of the induced draft fan 44 becomes a predetermined set pressure. Furthermore, the predetermined set pressure of the exhaust gas pressure sensor is set so that the amount of exhaust gas drawn in is appropriate according to the combustion rate of the boiler 10.

[0045] The pollution control unit controls the operation of the pollution control unit 80. This pollution control unit is electrically connected to the control unit 70 of the boiler 10, so that the pollution control unit 80 can obtain operating information of the boiler 10, and the boiler 10 can obtain operating information of the pollution control unit 80. For example, if the pollution control unit 80 stops operating, a stop signal is sent to the control unit 70.

[0046] In this embodiment, the control unit 70 determines abnormalities on the low-pressure and high-pressure sides of the exhaust gas pressure in the exhaust gas line L400 based on the detected pressure of the exhaust gas pressure sensor 41 which detects the exhaust gas pressure in the exhaust gas line L400 and a reference value stored in the exhaust gas pressure memory unit for determining abnormalities in the exhaust gas pressure, and performs an abnormality response operation. Figure 2 is a table showing an example of the first pressure value T1 to the fourth pressure value T4 of the exhaust gas E1 in the first embodiment. Regarding exhaust gas pressure, the normal range for exhaust gas pressure during boiler 10 operation corresponds to a range greater than the second pressure value T2 and less than the first pressure value T1 (a range greater than -0.5 kPa and less than 2.0 kPa). If the detection result of the exhaust gas pressure sensor 41 meets this range, boiler 10 and boiler system 1 are operating normally.

[0047] If the amount of exhaust gas discharged from the pollution control device 80 decreases due to blockage of the pollution control device 80 or the exhaust gas line L400, or a malfunction of the induced draft fan 44, the exhaust gas pressure detected by the exhaust gas pressure sensor 41 will exceed the normal range. Also, if the amount of exhaust gas E1 induced by the induced draft fan 44 to introduce exhaust gas E1 into the pollution control device 80 exceeds the appropriate amount induced, the exhaust gas pressure detected by the exhaust gas pressure sensor 41 will fall below the normal range.

[0048] When the exhaust gas pressure rises to the first pressure value T1, the control unit 70 determines that although a blockage (flue blockage) has occurred in the exhaust gas flow path such as the exhaust gas line L400, it will not immediately impede the operation of the boiler (low risk of flue blockage: exhaust gas E1 is not flowing easily). When the exhaust gas pressure rises further and reaches the third pressure value T3, the control unit 70 determines that the boiler 10 is on the verge of malfunctioning (high risk of flue blockage: exhaust gas E1 will not flow). Furthermore, if the exhaust gas pressure decreases, at the second pressure value T2, the control unit 70 determines that the degree of pressure drop inside the furnace is small and the risk of burner 12 misfiring is small. However, if it drops further and reaches the fourth pressure value T4, the control unit 70 determines that the pressure drop inside the furnace increases and the risk of burner 12 misfiring is large.

[0049] In this embodiment, if the exhaust gas pressure detected by the exhaust gas pressure sensor 41 becomes equal to or greater than the first pressure value T1 (2.0 kPa in the example shown in Figure 2) read from the exhaust gas pressure storage unit 72, the control unit 70 determines that it is difficult for exhaust gas E1 to flow into the exhaust gas line L400 and performs the first operation stop control.

[0050] In the first operation stop control, the control unit 70 closes the shut-off valves V21 and V23 of the ammonia fuel supply line L200 as described above, stopping the supply of ammonia fuel F2 to the burner 12. The control unit 70 also opens the shut-off valves V61 and V62 of the purge gas supply line L600 to purge the ammonia fuel supply line L200. Furthermore, the control unit 70 keeps the shut-off valve V11 of the first fuel supply line L100 open and continues operating the blower 31 of the air supply line L300, burning only the first fuel F1 for a predetermined time. Furthermore, the control unit 70 transmits to the pollution control unit (not shown) that the boiler 10 has been stopped by the first operation stop control, and the pollution control unit stops the operation of the induced draft fan 44.

[0051] As a result, any ammonia fuel F2 remaining in the piping of the ammonia fuel supply line L200 is discharged to the burner 12 and incinerated by the combustion of the first fuel F1. After the combustion of only the first fuel F1 continues for a predetermined time, the control unit 70 closes the shut-off valves V11 and V13 of the first fuel supply line L100, stops the operation of the blower 31, and stops the operation of the boiler 10. In addition, upon receiving notification that the boiler 10 has stopped, the abatement device control unit also stops the operation of the abatement device 80. This first shutdown control allows the boiler 10 to safely shut down by burning the ammonia fuel F2 remaining in the piping through the combustion of the first fuel F1 in the burner 12, thereby suppressing the emission of ammonia outside the system.

[0052] Furthermore, if the exhaust gas pressure rises and the exhaust gas pressure detected by the exhaust gas pressure sensor 41 becomes equal to or greater than the third pressure value T3 (3.0 kPa in the example shown in Figure 2) read from the exhaust gas pressure storage unit 72, the control unit 70 determines that the exhaust gas line L400 is blocked (exhaust gas E1 is not flowing) and performs a second operation stop control to immediately stop the boiler 10. In the second operation stop control, the control unit 70 closes the shut-off valves V21 and V23 of the ammonia fuel supply line L200 to stop the supply of ammonia fuel F2, and closes the shut-off valves V11 and V13 of the first fuel supply line L100 to stop the supply of the first fuel F1. In addition, it stops the operation of the blower 31 of the air supply line L300 to stop the supply of combustion air A1. When the control unit 70 performs the second operation stop control, the boiler 10 immediately stops operating. This prevents combustion problems due to rising furnace pressure, leakage from the exhaust gas line L400, etc. In addition, upon receiving the boiler 10's operation stop, the abatement device control unit also stops the abatement device 80 and the induced draft fan 44.

[0053] Furthermore, if the exhaust gas pressure detected by the exhaust gas pressure sensor 41 falls below the second pressure value T2 (in the example shown in Figure 2, -0.5 kPa) read from the exhaust gas pressure storage unit 72, the control unit 70 determines that the furnace pressure is beginning to decrease and that there is a risk of burner 12 misfire, and performs the first operation stop control. The first operation stop control is as described above. In this case, the pollution control unit (not shown) does not stop the operation of the induced fan 44, etc.

[0054] Furthermore, if the exhaust gas pressure decreases and the exhaust gas pressure detected by the exhaust gas pressure sensor 41 falls below the fourth pressure value T4 (in the example shown in Figure 2, -1.0 kPa) read from the exhaust gas pressure storage unit 72, the control unit 70 determines that there is a high risk of misfire due to a drop in furnace pressure and performs a second operation stop control to immediately stop the boiler 10. The second operational shutdown control is as described above.

[0055] Furthermore, for example, if the exhaust gas pressure sensor 41 detects a first pressure value T1 or higher, and the control unit 70 is performing the first operation stop control, and the exhaust gas pressure rises further, causing the exhaust gas pressure sensor 41 to detect a third pressure value T3 or higher, the control unit 70 performs the second operation stop control and immediately stops the operation of the boiler 10. Similarly, if the exhaust gas pressure drops further while the exhaust gas pressure sensor 41 is performing the first operation stop control, and the exhaust gas pressure sensor 41 is performing the second operation stop control, and the exhaust gas pressure sensor 41 is performing the fourth pressure value T4 or lower, the control unit 70 will perform the second operation stop control and immediately stop the operation of the boiler 10.

[0056] The control unit 70 stops the operation of the boiler 10 as described above in accordance with the exhaust gas pressure detected by the exhaust gas pressure sensor 41. This allows the boiler 10 to be safely shut down without combustion problems occurring due to rising furnace pressure, leakage of ammonia-containing exhaust gas E1 from the exhaust gas line L400, or misfires.

[0057] According to the embodiment described above, the following effects can be achieved. (1) The boiler 10 is a boiler provided in a boiler system 1 which includes a boiler 10 that burns ammonia fuel F2, which is a gaseous fuel containing ammonia, or a boiler 10 that burns ammonia fuel F2 and a first fuel F1 which has a faster combustion rate than ammonia fuel F2, an abatement device 80 that removes ammonia contained in exhaust gas E1 discharged from the boiler 10, and an exhaust gas line L400 that flows exhaust gas E1 from the boiler 10 to the abatement device 80. The boiler 10 includes a boiler body 11 that recovers heat from combustion gas produced by combustion, an exhaust gas pressure sensor 41 which is an exhaust gas pressure detection unit that detects the exhaust gas pressure of the exhaust gas line L400, and a control unit 70 that controls the operation of the boiler 10. The control unit 70 includes an exhaust gas pressure storage unit 72, which stores a first pressure value T1, which is a criterion for determining abnormalities on the high-pressure side of the exhaust gas pressure; a second pressure value T2, which is a criterion for determining abnormalities on the low-pressure side of the exhaust gas pressure and is smaller than the first pressure value; and a first operation stop control associated with the first pressure value T1 and the second pressure value T2, which stops the operation of the boiler 10 after burning only the first fuel F1. The control unit 70 performs the first operation stop control in at least one of the following cases: when the detection result of the exhaust gas pressure sensor 41, which is an exhaust gas pressure detection unit, is greater than or equal to the first pressure value T1 read from the exhaust gas pressure storage unit 72; or when the detection result of the exhaust gas pressure sensor 41, which is an exhaust gas pressure detection unit, is less than or equal to the second pressure value T2 read from the exhaust gas pressure storage unit 72.

[0058] When the exhaust gas pressure detected by the exhaust gas pressure sensor 41, which detects the exhaust gas pressure in the exhaust gas line L400, becomes equal to or greater than the first pressure value T1, or equal to or less than the second pressure value T2, the control unit 70 performs a first shutdown control, which involves burning only the first fuel F1, as is done when shutting down a normal boiler 10, and then shutting down the boiler 10. This allows for the detection of pressure changes in the exhaust gas line L400, which indicate malfunctions or abnormalities in the exhaust gas line L400 or the abatement device 80, while the boiler 10 and abatement device 80 are still operational. At this stage, the operation of the boiler 10 and abatement device 80 can be continued, and normal shutdown control can be performed promptly. Therefore, even if the boiler 10 or abatement device 80 is shut down in an emergency, the leakage of ammonia from the system due to the discharge or leakage of exhaust gas E1 containing ammonia that has accumulated in the boiler 10, exhaust gas line L400, and abatement device 80 can be suppressed. Furthermore, the period of unstable combustion and exhaust gas treatment leading up to the emergency shutdown of the boiler 10 or abatement device 80 can be interrupted by performing the first shutdown control, thereby suppressing abnormal ammonia leakage, such as ammonia leakage exceeding the standard value, or the detection of ammonia in an operating state where ammonia is not normally detected.

[0059] (2) The exhaust gas pressure memory unit 72 stores a third pressure value T3 which is greater than the first pressure value T1 and is a criterion for determining abnormalities on the high-pressure side of the exhaust gas pressure, a fourth pressure value T4 which is less than the second pressure value T2 and is a criterion for determining abnormalities on the low-pressure side of the exhaust gas pressure, and a second operation stop control which is associated with the third pressure value T3 and the fourth pressure value T4 and immediately stops the operation of the boiler 10. The control unit 70 performs the second operation stop control in at least one of the following cases: when the exhaust gas pressure rises and the detection result of the exhaust gas pressure sensor 41, which is the exhaust gas pressure detection unit, becomes greater than or equal to the third pressure value T3 read from the exhaust gas pressure memory unit 72, or when the exhaust gas pressure falls and the detection result of the exhaust gas pressure sensor 41, which is the exhaust gas pressure detection unit, becomes less than or equal to the fourth pressure value T4 read from the exhaust gas pressure memory unit 72.

[0060] If the exhaust gas pressure rises to a third pressure value T3 or higher, which is greater than the first pressure value T1, or if the exhaust gas pressure falls to a fourth pressure value T4 or lower, which is less than the second pressure value T2, the control unit 70 performs a second operation stop control to immediately stop the boiler 10. In other words, if a large abnormality occurs in the exhaust gas pressure of the exhaust gas line L400, the control unit 70 immediately stops the operation of the boiler 10. This prevents the continued leakage of ammonia due to unstable combustion or exhaust gas treatment of the boiler 10 or the abatement device 80, and also prevents the worsening of ammonia leakage and a decrease in safety due to malfunctions such as boiler 10 misfires.

[0061] (3) The boiler system 1 comprises a boiler 10 as described in at least one of (1) and (2) above, a pollution control device 80 for removing ammonia contained in the exhaust gas E1, and an exhaust gas line L400 for circulating the exhaust gas E1 from the boiler 10 to the pollution control device 80. Since the boiler system 1 includes the boiler 10 and the abatement device 80, when the exhaust gas pressure is within the permissible range and the boiler 10 is operating normally, it can remove and discharge the ammonia contained in the exhaust gas E1.

[0062] Furthermore, in such a boiler system 1, if a malfunction occurs in the abatement device 80 or the induced draft fan 44, or if the exhaust gas line becomes blocked (damper malfunction, filter clogging, etc.), the abnormality can be detected from the exhaust gas pressure in the exhaust gas line L400, and the boiler 10 can be safely stopped (first operation stop control) while suppressing ammonia leakage, or the boiler 10 can be stopped before the malfunction escalates.

[0063] In a system where exhaust gas E1 is drawn in by an induced draft fan 44 and treated by a pollution control device 80, if the amount drawn by the induced draft fan 44 is excessive relative to the amount of exhaust gas generated by the boiler 10, the exhaust gas pressure in the exhaust gas line L400 will fall below the appropriate pressure. A decrease in exhaust gas pressure reduces the furnace pressure of the boiler, increasing the risk of burner misfire. To address this safety reduction caused by a malfunction of the induced draft fan 44, a second pressure value T2 and a fourth pressure value T4 are provided to detect abnormalities on the low-pressure side that are below the appropriate exhaust gas pressure range. This allows for prompt and normal shutdown control (first shutdown control) while the boiler 10 and pollution control device 80 can continue operating, or for immediately stopping the operation of the boiler 10 (second shutdown control). As a result, the boiler system 1 can prevent the continued leakage of ammonia due to unstable combustion or exhaust gas treatment until the boiler 10 or the pollution control device 80 is shut down in an emergency, and can also prevent the worsening of ammonia leakage and the deterioration of safety due to the expansion of malfunctions such as fire failures in the boiler 10.

[0064] (Second Embodiment) The boiler system 2 of the second embodiment includes a boiler 20, a washing section 58, and a pollution control device 80. If the pollution control device 80 cannot treat the exhaust gas E1, the washing section 58 washes the exhaust gas E1. Figure 3 is a diagram illustrating the boiler system 2 of the second embodiment. The boiler system 2 of this embodiment comprises a boiler 20 equipped with a water washing section 58, an exhaust gas line L400, a pollution control device 80, and a boiler system control unit 90. Furthermore, the boiler system 2 of this embodiment is similar in form to the boiler system 1 shown in the first embodiment, except that the boiler 20 is equipped with a water washing section 58, the exhaust gas line L400 is equipped with a branch exhaust gas line L410, the feedwater line L500 is equipped with a second feedwater line L510, etc., and the boiler system control unit 90 is included. Therefore, in describing this embodiment, parts that perform the same functions as those in the first embodiment described above are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0065] In this embodiment, the exhaust gas line L400 includes a branch exhaust gas line L410 that branches off from the exhaust gas line L400 at a branching point upstream of the damper 42. At least a portion of the exhaust gas E1 flowing through the exhaust gas line L400 flows through the branch exhaust gas line L410. The upstream side of the branch exhaust gas line L410 is connected to the exhaust gas line L400, and the downstream side is connected to the second exhaust gas line L430 downstream of the pollution control device 80. The downstream side of the branch exhaust gas line L410 may be open to the atmosphere.

[0066] The branch exhaust gas line L410 is equipped with a damper 45. The damper 45 is an opening / closing unit that can open and close the flow path of the branch exhaust gas line L410, and the flow rate of exhaust gas E1 in the branch exhaust gas line L410 is adjusted by adjusting the opening degree of the damper. Specifically, the damper 45 is rotatably positioned between a closed state in which the flow path of the branch exhaust gas line L410 is blocked and an open state in which it rotates from this closed state to a predetermined angle (e.g., 90 degrees) to open the flow path of the branch exhaust gas line L410. The damper 45 is electrically connected to the control unit 70 and is controlled by signals transmitted from the control unit 70.

[0067] In this embodiment, the water supply line L500 is located downstream of the pump 51 and includes a second water supply line L510 that branches off from the upstream side of the shut-off valves V51 and V52. The second water supply line L510 is equipped with a shut-off valve V56 and supplies water W2 from a water source (not shown) to the watering section 57. The shut-off valve V56 opens and closes the flow path of the second feedwater line L220 to supply or stop water W2 to the water spraying unit 57. The shut-off valve V56 is electrically connected to the boiler system control unit 90 and is controlled by signals transmitted from the boiler system control unit 90.

[0068] The water washing section 58 removes ammonia from the exhaust gas E1 by washing it with water. In this embodiment, the water washing section 58 corresponds to the economizer 55 and the water spraying section 57, and water is sprayed from the water spraying section 57 onto the heat exchanger of the economizer 55 to remove ammonia from the exhaust gas E1 by washing it with water. The water spraying unit 57 is positioned above the economizer 55 and sprays water W2 toward the heat exchanger of the economizer 55. As a result, at least a portion of the ammonia in the exhaust gas E1 dissolves in the sprayed water W2, removing the ammonia contained in the exhaust gas E1. This water washing unit 58 is located in the exhaust gas line L400 upstream of the branching point of the branch exhaust gas line L410.

[0069] A blowdown discharge line L420 is provided near the bottom of the economizer 55. Water W2 containing dissolved ammonia, sprayed from the water spraying section 57, is discharged out of the system as blowdown through the blowdown discharge line L420. Since a blowdown discharge line L420 is generally located near the economizer 55, the water W2 containing dissolved ammonia can be easily discharged from the blowdown discharge line L420. Furthermore, by spraying the water W2 onto the heat exchanger of the economizer 55, the ammonia can be efficiently dissolved in the water W2 and removed by utilizing the water film on the surface of the heat exchanger.

[0070] In addition, the washing section may be a wet scrubber equipped with a water spraying section 57 and a packing material, and may be installed independently of the boiler 20 on the upstream side of the exhaust gas line L400 where the branched exhaust gas line L410 branches off from the exhaust gas line L400. Furthermore, although the example shown illustrates that the water supplied to the sprinkler unit 57 is supplied by a second feedwater line L510 branched from the feedwater line L500 that supplies water to the boiler 20, the system is not limited to this, and water may be supplied from a separate feedwater system from the feedwater line L500.

[0071] In this embodiment, when the exhaust gas pressure rises and the detection result of the exhaust gas pressure sensor 41 becomes equal to or greater than the third pressure value T3 (3.0 kPa in the example shown in Figure 2) read from the exhaust gas pressure storage unit 72, the control unit 70 determines that the exhaust gas line L400 is blocked (exhaust gas E1 is not flowing), performs a second operation stop control, and transmits information to the boiler system control unit 90 that the exhaust gas line pressure is equal to or greater than the third pressure value T3.

[0072] When the boiler system control unit 90 receives information from the control unit 70 that the exhaust gas line pressure is equal to or greater than the third pressure value T3, it performs exhaust gas flushing control. Specifically, the boiler system control unit 90 opens the shut-off valve V56 to open the flow path of the second feedwater line L510 and supplies water W2 to the water spraying unit 57. The boiler system control unit 90 also opens the damper 45 of the branch exhaust gas line L410 to secure the exhaust flow path. Furthermore, the boiler system control unit 90 sends signals to the abatement device control unit (not shown) to stop the induced draft fan 44 and close the damper 42 of the exhaust gas line L400, thereby stopping the inflow of exhaust gas E1 to the abatement device 80. This series of controls is called exhaust gas washing control.

[0073] When water W2 is supplied to the water spraying section 57, in the washing section 58, water W2 is sprayed from the water spraying section 57 onto the heat exchanger of the economizer 55, and ammonia in the exhaust gas E1 dissolves in the water W2. The water W2 containing dissolved ammonia is then discharged from the blowdown discharge line L420 and treated by a treatment device (not shown).

[0074] Furthermore, when the boiler system control unit 90 performs exhaust gas washing control, it sends a signal to the control unit 70 of the boiler 20 to operate the blower 31 of the air supply line L300, thereby operating the blower 31. The ammonia-containing gas remaining in the boiler 20 is pushed out (air purged) by the air A1 supplied from the blower 31, washed in the washing section 58, and discharged outside the system by flowing through the branch exhaust gas line L410.

[0075] The boiler system control unit 90 continues to spray water W2 from the spraying unit 57 and supply air A1 from the blower 31, then closes the shut-off valve V56 of the second feedwater line L510, stopping the supply of water W2 to the spraying unit 57 and ending the series of exhaust gas washing controls. As a result, even if the boiler 20 stops combustion due to the second operation stop control, ammonia contained in the exhaust gas can be removed, and the leakage of ammonia into the environment can be suppressed.

[0076] The boiler system control unit 90 also performs the above-described exhaust gas flushing control when the exhaust gas pressure decreases and the detection result of the exhaust gas pressure sensor 41 falls below the fourth pressure value T4 (in the example shown in Figure 2, -1.0 kPa) read from the exhaust gas pressure storage unit 72. Furthermore, the boiler system control unit 90 may be configured to perform the exhaust gas washing control described above when the detection result of the exhaust gas pressure sensor 41 is 3rd pressure value T3 or higher, and not perform the exhaust gas washing control described above when it is 4th pressure value T4 or lower. For example, if the cause of the exhaust gas pressure drop is on the boiler 20 side and the ammonia removal by the ammonia removal device 80 is functioning effectively, the ammonia can be removed by the ammonia removal device 80.

[0077] If the control unit 70 immediately stops the boiler 20 (emergency stop) due to the second operation stop control, piping purging of the ammonia fuel supply line L200 is not performed, and ammonia fuel remains in the ammonia fuel supply line L200, etc. In this embodiment, the ammonia remaining in the boiler 20 can be removed from the exhaust gas E1 by washing with water in the washing section 58, which consists of the economizer 55 and the water spraying section 57, thereby suppressing the leakage of ammonia outside the system and allowing the operation of the boiler 20 to be safely stopped.

[0078] In addition to the effects of (1) and (2) above, the boiler system 2 of this embodiment can provide the following effects. (4) The boiler system 2 is a boiler system comprising a boiler 20, a pollution control device 80 that removes ammonia contained in exhaust gas E1 discharged from the boiler 20, and an exhaust gas line L400 that flows exhaust gas E1 from the boiler 10 to the pollution control device 80, and further comprising a boiler system control unit 90 that controls the operation of the boiler system, and a washing unit 58 that washes away ammonia in the exhaust gas E1 with water. The exhaust gas line L400 comprises a branch exhaust gas line L410 that branches off from the exhaust gas line L400 and through which at least a portion of the exhaust gas E1 flows, and a damper 45 that is provided in the branch exhaust gas line L410 and is an opening / closing unit that can open and close the flow path of the branch exhaust gas line L410. The water washing section 58 is located upstream of the branch of the branch exhaust gas line L410 from the exhaust gas line L400. The boiler system control unit 90 opens the damper 45, which is an opening / closing section, when the detection result of the exhaust gas pressure sensor 41, which is an exhaust gas pressure detection section, becomes equal to or greater than the third pressure value T3 read from the exhaust gas pressure storage section 72, or when the detection result of the exhaust gas pressure sensor 41 becomes equal to or less than the fourth pressure value T4 read from the exhaust gas pressure storage section 72, and discharges the exhaust gas E1 washed by the water washing section 58 from the branch exhaust gas line L410.

[0079] When the boiler 20 is immediately stopped (emergency stop) by the second operation stop control, the boiler 20 removes unburned ammonia contained in the exhaust gas E1 and ammonia mixed in the exhaust gas E1 and air-purged combustion air A1 remaining in the ammonia fuel supply line L200, etc., by dissolving them in water W2 using the economizer 55 and water spraying section 57, which are the washing section 58, and discharges the exhaust gas E1 and air-purged combustion air A1 through the branch exhaust gas line L410. This prevents ammonia from leaking out of the system even when the boiler 20 is emergency stopped.

[0080] (Transformed form) The present invention is not limited to the embodiments described above, and various modifications and changes are possible, all of which fall within the scope of the present invention. In each embodiment, boilers 10 and 20 are shown to burn ammonia fuel F2 and first fuel F1 simultaneously. However, boiler 20 may be capable of burning ammonia fuel F2 simultaneously with first fuel F1, and then burning only ammonia fuel F2 (ammonia-only combustion). In that case, during the first operation stop control, it is preferable that the control unit 70 opens the shut-off valves V11 and V13 of the first fuel supply line L100 to start supplying the first fuel F1 to the burner 12, before closing the shut-off valves V21 and V23 of the ammonia fuel supply line L200 or opening the shut-off valves V61 and V62 of the purge gas supply line L600.

[0081] In each embodiment, the boilers 10 and 20 are shown to be equipped with an economizer 55, but the invention is not limited to this, and may be configured without an economizer 55.

[0082] In each embodiment, the normal range of exhaust gas pressure is defined as the range that is greater than the second pressure value and less than the first pressure value T1. However, the exhaust gas pressure storage unit 72 may also store an acceptable range that takes into account the acceptable difference (deviation) from this normal range of exhaust gas pressure. For example, if the goal is to enhance the safety of the operation of boilers 10, 20 and boiler systems 1, 2, the control unit 70 may perform a first operation stop control when the detection result of the exhaust gas pressure sensor 41 falls outside the normal range. Alternatively, if the goal is to prioritize the continued operation of boilers 10, 20 and boiler systems 1, 2, the control unit 70 may perform a first operation stop control when the detection result of the exhaust gas pressure sensor 41 falls outside the acceptable range.

[0083] In each embodiment, the control unit 70 may be configured to include an exhaust gas pressure storage unit 72 separately from the storage unit 71. Furthermore, in each embodiment, the abatement device 80 may be a device that removes ammonia by combustion or catalytic combustion.

[0084] In each embodiment, the control unit 70 may, in the first operation stop control, stop the supply of ammonia fuel F2 and first fuel F1, then blow air into the furnace to perform an air purge inside the furnace, perform an inert gas purge (pipe purge) by supplying an inert gas to the ammonia fuel supply line L200 during the air purge, and then terminate the air purge after the pipe purge is completed. Furthermore, in each embodiment, the control unit 70 may, in the first operation stop control, stop the supply of ammonia fuel F2, then stop the combustion of the first fuel F1, then start air purging in the furnace, start piping purging during air purging in the furnace, and end air purging after piping purging is completed. Furthermore, in each embodiment, the control unit 70 may, in the first operation stop control, stop the supply of ammonia fuel F2, perform an air purge in the furnace for a predetermined time, and then stop operation. At this time, the ammonia discharged from the boiler 10 by the air purge is removed by the abatement device 80.

[0085] In the second embodiment, the boiler 20 is provided with a steam injection line (not shown) that supplies steam from the steam phase portion of the boiler body 11 to the economizer 55. Simultaneously with the opening of the damper 45 of the branch exhaust gas line L410, an automatic valve (not shown) of the steam injection line is opened to inject steam into the economizer 55, thereby washing away ammonia in the exhaust gas E1. Furthermore, in the second embodiment, if exhaust gas E1 can be induced by the induced fan 44 and exhausted via the abatement device 80, the branched exhaust gas line L410 may be omitted, and the water-washed exhaust gas E1 may be discharged from the exhaust gas line L400.

[0086] In the second embodiment, the boiler system control unit 90 opens the shut-off valve V56 in exhaust gas washing control, but the embodiment is not limited to this, and the control unit 70 may open the shut-off valve V56. Furthermore, although the second embodiment shows an example in which the boiler 20 is equipped with the exhaust gas pressure sensor 41, the system is not limited to this, and the boiler system 2 may be equipped with the exhaust gas pressure sensor 41, and the control unit 70 may receive the signal from the exhaust gas pressure sensor 41 either directly or via the boiler system control unit 90. Furthermore, in the second embodiment, the boiler system control unit 90 was shown to receive information regarding exhaust gas pressure values, such as the exhaust gas line pressure being equal to or greater than the third pressure value T3, from the control unit 70. However, it is not limited to this, and the control unit 90 may also receive a signal from the control unit 70 to start the second operation stop control. Furthermore, in the second embodiment, an example was shown in which the boiler system control unit 90 opens the shut-off valve V56 to start supplying water to the water spraying unit 57 and washes away ammonia in the exhaust gas E1 in the washing unit 58. However, the system is not limited to this, and the start of water supply to the water spraying unit 57 by opening the shut-off valve V56 may be performed by the control unit 70 in addition to the second operation stop control.

[0087] In the first embodiment, the system may be configured to include a boiler system control unit that controls the operation of the boiler system 1.

[0088] The embodiments and variations of this invention can be used in combination as appropriate, but a detailed explanation is omitted. Furthermore, the present invention is not limited to the embodiments described above.

[0089] Furthermore, since the present invention promotes the use of ammonia as a fuel that does not emit carbon dioxide, it can contribute, for example, to United Nations Sustainable Development Goal (SDG) 7, "Ensure access to affordable, reliable, sustainable and modern energy." [Explanation of Symbols]

[0090] 1,2 Boiler System 10,20 boilers 11 Can body 12 burners L100 Fuel supply line 1 L200 Ammonia Fuel Supply Line L300 Air Supply Line L400 exhaust gas line L410 Branch Exhaust Gas Line L500 Water supply line L510 Second water supply line F1 1st fuel F2 Ammonia Fuel G1 Purge Gas A1 Combustion air W1 Water Supply W2 Water

Claims

1. A boiler used in a boiler system comprising: a boiler that burns ammonia fuel containing ammonia, or a boiler that burns a first fuel having a faster combustion rate than the ammonia fuel and the ammonia fuel; a decontamination device that removes ammonia contained in the exhaust gas discharged from the boiler; and an exhaust gas line that flows the exhaust gas from the boiler to the decontamination device, The aforementioned boiler is A boiler that recovers heat from combustion gases produced by combustion, An exhaust gas pressure detection unit detects the exhaust gas pressure in the aforementioned exhaust gas line, A control unit that controls the operation of the boiler, Equipped with, The control unit includes an exhaust gas pressure storage unit, The exhaust gas pressure storage unit is A first pressure value which is a criterion for determining abnormalities on the high-pressure side of the exhaust gas pressure, This is a criterion for determining an abnormality on the low-pressure side of the exhaust gas pressure, and includes a second pressure value that is smaller than the first pressure value, A first operation stop control, associated with the first pressure value and the second pressure value, which stops the operation of the boiler after burning only the first fuel, Remember this, The control unit performs the first operation stop control in at least one of the following cases: when the detection result of the exhaust gas pressure detection unit is equal to or greater than the first pressure value read from the exhaust gas pressure storage unit, or when the detection result of the exhaust gas pressure detection unit is equal to or less than the second pressure value read from the exhaust gas pressure storage unit. Boiler.

2. The exhaust gas pressure storage unit is This is a criterion for determining an abnormality on the high-pressure side of the exhaust gas pressure, and is a third pressure value that is greater than the first pressure value, This is a criterion for determining abnormalities on the low-pressure side of the exhaust gas pressure, and is a fourth pressure value that is smaller than the second pressure value, A second operation stop control, associated with the third pressure value and the fourth pressure value, immediately stops the operation of the boiler, Remember this, The control unit performs the second operation stop control in at least one of the following cases: when the detection result of the exhaust gas pressure detection unit is equal to or greater than the third pressure value read from the exhaust gas pressure storage unit, or when the detection result of the exhaust gas pressure detection unit is equal to or less than the fourth pressure value read from the exhaust gas pressure storage unit. The boiler according to claim 1.

3. A boiler according to claim 1 or claim 2, A decontamination device for removing ammonia contained in the exhaust gas, An exhaust gas line for circulating the exhaust gas from the boiler to the pollution control device, A boiler system equipped with [a specific feature / feature].

4. The boiler according to claim 2, A decontamination device for removing ammonia contained in the exhaust gas discharged from the boiler, An exhaust gas line for circulating the exhaust gas from the boiler to the pollution control device, A boiler system comprising, A boiler system control unit that controls the operation of the boiler system, A water washing section for washing away ammonia from the exhaust gas, Equipped with, The aforementioned exhaust gas line is A branch exhaust gas line that branches off from the aforementioned exhaust gas line and through which at least a portion of the exhaust gas flows, An opening / closing unit is provided in the aforementioned branch exhaust gas line and is capable of opening and closing the flow path of the aforementioned branch exhaust gas line, Equipped with, The water washing section is provided upstream of the branch exhaust gas line from the exhaust gas line. The boiler system control unit is: When the detection result of the exhaust gas pressure detection unit becomes equal to or greater than the third pressure value read from the exhaust gas pressure storage unit, or when the detection result of the exhaust gas pressure detection unit becomes equal to or less than the fourth pressure value read from the exhaust gas pressure storage unit, the opening / closing unit is opened, and the exhaust gas washed by the water washing unit is discharged from the branch exhaust gas line. Boiler system.

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