JP2020098069A - Boiler and control method for the same - Google Patents

Abstract

To appropriately reduce NOx and CO.SOLUTION: A boiler 1 includes a can body 10 having water pipes 51, 52, 53, a burner 16 connected to the can body 10 for supplying primary fuel F1 and air A into the can body 10, a secondary fuel supply part 24 for supplying secondary fuel F2 into the can body 10 on the further downstream side than the burner 16 in the flowing direction of combustion gas, a cooling line 26 for introducing cooling fluid G0 to reduce the temperature of a predetermined space in the can body 10 on the further downstream side than the burner 16 in the flowing direction of the combustion gas, a flow amount adjustment part 28 provided in the cooling line 26 for making the flow amount of the cooling fluid G0 adjustable to be introduced from the cooling line 26 into the can body 10, and a control part for controlling the flow amount adjustment part 28 to supply the flow amount of the cooling fluid G0 to be introduced into the can body 10 so that the temperature of the predetermined space becomes 800°C-1200°C.SELECTED DRAWING: Figure 2

Description

The present invention relates to a boiler and a boiler control method.

As a boiler that generates steam by using heat generated by burning fuel gas, for example, as in Patent Documents 1 and 2, a fuel supply that further supplies fuel gas to a downstream side of a burner that supplies fuel gas into a can body. Some parts are equipped with a part to perform two-stage combustion. Patent Documents 1 and 2 describe that the above configurations can reduce NOx, CO, and oxygen concentrations contained in exhaust gas. Further, Patent Document 2 describes that exhaust gas from the can body is sucked by an ejector and recirculated to the can body.

JP, 2006-220373, A JP, 2011-133180, A

For example, in Patent Document 2, the position where the combustion gas is supplied is adjusted according to the amount of combustion, but for two-stage combustion as in Patent Documents 1 and 2, NOx and NOx There is room for further improvement in reducing CO.

The aspect of this invention aims at providing the boiler and the control method of a boiler which reduce NOx and CO appropriately.

According to the aspect of the present invention, a can body having a water pipe, a burner that is connected to the can body and supplies primary fuel and air into the can body, and a downstream side of the burner in a flow direction of combustion gas. A secondary fuel supply unit that supplies a secondary fuel into the can body, and a cooling line that introduces a cooling fluid that reduces the temperature of a predetermined space in the can body downstream of the burner in the flow direction of combustion gas, A flow rate adjusting unit provided in the cooling line and capable of adjusting the flow rate of the cooling fluid introduced into the can body from the cooling line, and controlling the flow rate adjusting unit so that the temperature of the predetermined space is 800° C. or more. There is provided a boiler having a control unit that supplies a flow rate of the cooling fluid introduced into the can body at 1200° C. or lower.

According to the aspect of the present invention, a can body having a water pipe, a burner that is connected to the can body and supplies primary fuel and air into the can body, and a burner downstream of the burner in the flow direction of combustion gas. A secondary fuel supply unit that supplies a secondary fuel to the can body, and a cooling line that introduces a cooling fluid that reduces the temperature of a predetermined space in the can body downstream of the burner in the flow direction of combustion gas. And a flow rate adjusting unit which is provided in the cooling line and is capable of adjusting the flow rate of the cooling fluid introduced into the can body from the cooling line. A method for controlling a boiler is provided, which controls and supplies a flow rate of the cooling fluid introduced into the can body such that the temperature of the predetermined space is 800° C. or higher and 1200° C. or lower.

According to the aspect of the present invention, a boiler and a boiler control method for appropriately reducing NOx and CO are provided.

FIG. 1 is a schematic sectional view of a boiler according to the first embodiment. FIG. 2 is a schematic partial cross-sectional view of the boiler according to the first embodiment. FIG. 3 is a schematic block diagram of the control device according to the first embodiment. FIG. 4 is a graph showing the relationship among the primary fuel amount, the secondary fuel amount, and the cooling fluid amount. FIG. 5: is a flowchart which shows an example of the control method of the boiler system which concerns on this embodiment. FIG. 6 is a schematic cross-sectional view of the boiler according to the second embodiment. FIG. 7 is a schematic diagram of the ejector according to the second embodiment.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The constituent elements of the embodiments described below can be appropriately combined. In addition, some components may not be used.

In the following description, the combustion gas is a concept including at least one of the one in which the combustion reaction of the fuel gas is completed and the fuel gas in the combustion reaction, and the one in which the combustion reaction of the fuel gas is completed and the fuel in the combustion reaction. The concept includes both the case of having both of the gases, the case of having only the fuel gas in the combustion reaction, and the case of having only the one in which the combustion reaction of the fuel gas is completed.

(First embodiment)
(Overall structure of boiler)
FIG. 1 is a schematic sectional view of a boiler according to the first embodiment. FIG. 2 is a schematic partial cross-sectional view of the boiler according to the first embodiment. FIG. 2 is a schematic partial cross-sectional view when the boiler 1 according to the first embodiment is viewed from the Z direction side described later, that is, when the boiler 1 is looked down from above in the vertical direction. As shown in FIGS. 1 and 2, the boiler 1 according to the first embodiment includes a can body 10, a blower 12, a duct 14, a burner 16, an exhaust stack 18, and a fuel supply unit 20 (see FIG. 2 ). ), a primary fuel supply unit 22, a secondary fuel supply unit 24 (see FIG. 2), a cooling line 26 (see FIG. 2), a flow rate adjusting unit 28 (see FIG. 2), and a control device 30. ..

As shown in FIG. 1, the can body 10 includes a main body portion 40, an upper header 42, a lower header 44, and a water pipe group 50. In the present embodiment, the X direction is the flow direction of the combustion gas flowing inside the main body 40. Further, a direction that is orthogonal to the X direction and is along the vertical direction and that is directed toward the upper side in the vertical direction is referred to as the Z direction. The Z direction is a direction overlapping with the vertical direction in the present embodiment, but is not limited to the vertical direction. The main body 40 is a housing whose longitudinal direction is along the X direction, and accommodates the water tube group 50 therein. The upper header 42 is a header connected to the end of the main body 40 on the Z direction side, here, the vertical direction side. The lower header 44 is a header connected to the end of the main body 40 on the side opposite to the Z direction, here, the lower side in the vertical direction.

The water pipe group 50 has a plurality of water pipes 51, 52, 53 through which water or steam flows. The water pipes 51, 52, 53 are provided in the main body 40, extend along the Z direction, and connect the upper header 42 and the lower header 44. As shown in FIG. 2, the plurality of water pipes 51 (outer water pipes) are located at both ends of the main body 40 and are arranged along the direction in which the combustion gas flows, that is, the X direction. The plurality of water pipes 53 (central water pipes) are located inside the water pipe 51 and are arranged along the X direction. The plurality of water pipes 52 (intermediate water pipes) are located between the water pipes 51 and 53 and are arranged along the X direction. In addition, a connection wall 54 that extends along the X direction and connects the plurality of water pipes 51 to each other is provided in the main body portion 40. The space surrounded by the water pipe 51, the connecting wall 54, the upper header 42, and the lower header 44 forms a gas flow space. The water pipes 52 are arranged so that the distance between the some water pipes 52 along the X direction is longer than the distance between the other water pipes 52 along the X direction. That is, a part of the water pipe 52 is removed. In the gas flow space, the space between the water pipes 52 having the long distance, that is, the space removed from the water pipes 52 is wider than the space between the other water pipes. Hereinafter, the space between the water pipes 52 having a long distance is referred to as a combustion promotion space S. Since the combustion promotion space S is kept wide, combustion, that is, oxidation of CO in the combustion gas is promoted. The combustion promoting space S is not limited to the space between the water pipes 52 as long as it is kept wider than the other space surrounded by the water pipes, and is a space surrounded by arbitrary water pipes. Good. For example, in the main body portion 40, by making the diameter of the water pipe in the upstream space in the combustion gas flow direction smaller than the diameter of the downstream space in the combustion gas flow direction, the upstream in the combustion gas flow direction The pitch of the water tubes in the side space may be larger than the pitch of the water tubes in the space on the downstream side in the flow direction of the combustion gas. In this case, the combustion promoting space S may be provided in the upstream space in the flow direction of the combustion gas. However, the combustion promoting space S does not necessarily have to be provided.

The blower 12 supplies the air A for mixing with the primary fuel F1 described later. The duct 14 is a duct connected to the blower 12, and the air A supplied from the blower 12 flows. In addition, the duct 14 is connected to the primary fuel supply unit 22. Specifically, as shown in FIG. 2, the primary fuel supply unit 22 has a fuel supply line 60 and a primary fuel adjustment valve 62. The fuel supply line 60 has one end connected to the fuel supply unit 20 that supplies the fuel F, and the other end connected to the duct 14. Further, the fuel supply line 60 is provided with a primary fuel adjustment valve 62. The fuel F supplied from the fuel supply unit 20 flows through the fuel supply line 60, and at least a part of the flowing fuel F is supplied into the duct 14 as the primary fuel F1 via the primary fuel adjustment valve 62. The primary fuel F1 supplied from the fuel supply line 60 is mixed with the air A supplied from the blower 12 in the duct 14 to generate a mixed gas F1A. The fuel F (that is, the primary fuel F1 and the secondary fuel F2 described later) is a combustible fuel gas such as natural gas or propane gas, but may be any fuel. The opening/closing of the primary fuel adjusting valve 62 is controlled by the control device 30 to adjust the supply amount of the primary fuel F1 to the duct 14.

Further, as shown in FIG. 1, the duct 14 has a pressure reducing member 12A on the upstream side of the flow of the air A with respect to the location where the fuel supply line 60 is connected. The depressurizing member 12A is a member that lowers the pressure of the air A on the downstream side of the flow of the air A than itself by lowering the pressure of the air A on the upstream side of the flow of the air A, for example, by narrowing the flow path. Is. The pressure reducing member 12A is, for example, punching metal in the present embodiment. Further, the boiler 1 has an air differential pressure sensor 12B that detects a differential pressure between the pressure on the downstream side of the pressure reducing member 12A and the pressure on the downstream side of the pressure reducing member 12A. The air differential pressure sensor 12B detects the differential pressure between the pressure of the air A on the downstream side of the pressure reducing member 12A in the duct 14 and the pressure of the air A on the upstream side of the pressure reducing member 12A, and provides information on the detected differential pressure. Output to the control device 30.

Further, as shown in FIG. 2, the primary fuel supply unit 22 further includes a pressure reducing member 64 and a fuel differential pressure sensor 66. The pressure reducing member 64 is provided in the fuel supply line 60, and for example, by narrowing the flow path, the pressure reducing member 64 is more downstream than the pressure of the primary fuel F1 on the upstream side of the flow of the fuel F than itself and the downstream side of the flow of the fuel F on itself. It is a member that lowers the pressure of the primary fuel F1. More specifically, the pressure reducing member 64 is provided on the downstream side of the primary fuel regulating valve 62 and on the upstream side of the connection point of the fuel supply line 60 with the duct 14. In the present embodiment, the pressure reducing member 64 is, for example, an orifice. Further, the fuel differential pressure sensor 66 detects the differential pressure between the pressure on the downstream side of the pressure reducing member 64 and the pressure on the downstream side of the pressure reducing member 64. The fuel differential pressure sensor 66 detects the differential pressure between the pressure of the primary fuel F1 downstream of the pressure reducing member 64 and the pressure of the primary fuel F1 upstream of the pressure reducing member 64 in the fuel supply line 60, and the detected difference is detected. The pressure information is output to the control device 30.

The duct 14 is also connected to the main body portion 40 of the can body 10. The duct 14 is connected to a portion of the main body 40 on the side opposite to the X direction, that is, a portion on the upstream side in the flow direction of the combustion gas. Further, a burner 16 is provided at the connection point between the duct 14 and the main body 40. That is, it can be said that the burner 16 is connected to the can body 10 and is connected to a location on the opposite side of the main body 40 from the X direction. The mixed gas F1A flowing through the duct 14 is supplied to the burner 16. The burner 16 supplies the mixed gas F1A, that is, the primary fuel F1 and the air A into the main body portion 40 of the can body 10.

The exhaust pipe 18 is connected to the main body portion 40 of the can body 10, and more specifically, is connected to a portion on the X direction side of the main body portion 40 (a portion on the most downstream side in the combustion gas flow direction). The combustion gas in the body 40 is discharged from the body 40 to the exhaust stack 18 as exhaust gas.

The secondary fuel supply unit 24 supplies the secondary fuel F2 into the can body 10 on the downstream side of the burner 16 in the flow direction of the combustion gas. Specifically, the secondary fuel supply unit 24 has secondary fuel supply lines 70 and 74 and a secondary fuel adjustment valve 72, as shown in FIG. The secondary fuel supply line 70 is connected to the fuel supply line 60. More specifically, the secondary fuel supply line 70 is connected to the fuel supply line 60 at a location between the connection location of the fuel supply section 20 and the connection location of the primary fuel regulating valve 62. Therefore, in the fuel supply line 60, at least a part of the fuel F is supplied as the secondary fuel F2 from the fuel supply unit 20. The secondary fuel adjustment valve 72 is provided in the secondary fuel supply line 70. The opening/closing of the secondary fuel adjustment valve 72 is controlled by the control device 30 to adjust the supply amount of the secondary fuel F2 to the secondary fuel supply line 70.

The secondary fuel supply line 74 is connected to a position on the downstream side of the flow of the secondary fuel F2 with respect to the connection position of the secondary fuel supply line 70 with the secondary fuel adjustment valve 72. The secondary fuel supply line 74 is supplied with the secondary fuel F2 from the secondary fuel supply line 70 via the secondary fuel adjustment valve 72. The secondary fuel supply line 74 is also connected to the main body portion 40 of the can body 10. More specifically, the secondary fuel supply line 74 is connected to a portion of the main body portion 40 on the X direction side (downstream side in the combustion gas flow direction) with respect to the connection portion with the burner 16. Therefore, the secondary fuel supply line 74 supplies the secondary fuel F2 from the secondary fuel supply line 70 into the can body 10 on the downstream side of the burner 16 in the flow direction of the combustion gas. Furthermore, the secondary fuel supply line 74 is connected to the downstream side of the location in the can body 10 where combustion with the primary fuel F1 starts, that is, the downstream side of the ignition means (not shown). Further, the secondary fuel supply line 74 should be connected to a position where the temperature of the combustion gas is 800° C. or higher, that is, a position where the secondary fuel F2 is appropriately self-combusted and the generation of CO can be suppressed. Is preferred. In addition, the secondary fuel supply line 74 is preferably connected to a location on the opposite side of the combustion promoting space S in the X direction (upstream side in the combustion gas flow direction). In the present embodiment, two secondary fuel supply lines 74 are provided branching from the secondary fuel supply line 70, and each of them is connected to the main body 40. However, the number of the secondary fuel supply lines 74 is arbitrary and may be one, for example.

As shown in FIG. 2, the cooling line 26 has one end connected to the exhaust stack 18 and the other end connected to the secondary fuel supply line 70. The cooling line 26 is supplied with the exhaust gas from the exhaust stack 18, that is, the combustion gas discharged from the can body 10 as the cooling fluid G0. The cooling line 26 is a part of the secondary fuel supply line 70 on the downstream side of the flow of the secondary fuel F2 with respect to the connection part of the secondary fuel regulating valve 72, and is more than the connection part of the secondary fuel supply line 74. It is connected to a location on the upstream side of the flow of the secondary fuel F2. Therefore, the cooling fluid G0 flowing through the cooling line 26 is supplied to the secondary fuel supply line 74 via the secondary fuel supply line 70, and is supplied from the secondary fuel supply line 74 to the burner 16 in the flow direction of the combustion gas. It is introduced into the downstream can body 10. Furthermore, the secondary fuel F2 is also supplied to the secondary fuel supply line 74. Therefore, in the secondary fuel supply line 74, the secondary fuel F2 and the cooling fluid G0 are mixed to generate a mixed gas F2A. The secondary fuel supply line 74 introduces the mixed gas F2A, that is, the secondary fuel F2 and the cooling fluid G0 into the can body 10.

Further, the flow rate adjusting unit 28 is provided in the cooling line 26. The flow rate adjusting unit 28 adjusts the supply amount of the cooling fluid G0 introduced into the can body 10 from the cooling line 26 via the secondary fuel supply line 74 under the control of the control device 30. In the present embodiment, the flow rate adjusting unit 28 is a fan. The flow rate adjusting unit 28 sucks the cooling fluid G0 (exhaust gas) from the exhaust stack 18 and supplies the cooling fluid G0 into the cooling line 26, and the cooling fluid G0 supplied into the cooling line 26 is passed through the secondary fuel supply line 74. Is supplied into the can body 10. The flow rate adjusting unit 28 adjusts the supply amount of the cooling fluid G0 to be supplied to the can body 10 by the control device 30 controlling the number of rotations of the built-in blades (not shown). However, the flow rate adjusting unit 28 is not limited to controlling the rotation speed as long as the supply amount of the cooling fluid G0 supplied by the control of the control device 30 can be adjusted, and the cooling fluid G0 can be controlled by any method. The supply may be adjusted. For example, the flow rate adjusting unit 28 may adjust the supply amount of the cooling fluid G0 by controlling the opening of the built-in vane.

In addition, in this embodiment, the cooling line 26, the secondary fuel supply line 70, and the secondary fuel supply line 74 are described as separate tubes. However, since the cooling line 26, the secondary fuel supply line 70, and the secondary fuel supply line 74 are connected, the cooling line 26, the secondary fuel supply line 70, and the secondary fuel supply line 74 are combined into one. In other words, it is a tube.

In the boiler 1 configured as described above, first, the primary fuel F1 introduced from the fuel supply line 60 and the air A supplied from the blower 12 are mixed in the duct 14 to generate a mixed gas F1A. It The mixed gas F1A is supplied from the burner 16 into the main body portion 40 of the can body 10. The mixed gas F1A supplied into the main body 40 is ignited by an igniting means (not shown), and the burner 16 forms a combustion gas in a combustion reaction accompanied by a flame. The combustion gas flows in the X direction side while exchanging heat with the water pipes 51, 52, 53 in the main body 40. Further, the cooling fluid G0 introduced from the cooling line 26 and the secondary fuel F2 introduced from the secondary fuel supply line 70 are mixed in the secondary fuel supply line 74, and are mixed gas F2A as the main body portion. The gas is introduced into a portion of the burner 40 downstream of the burner 16 in the flow of combustion gas. The mixed gas F2A comes into contact with the combustion gas and burns. As described above, the boiler 1 performs the two-stage combustion by supplying the mixed gas F1A and F2A from the burner 16 and the secondary fuel supply line 74. The combustion gas, which is supplied with the mixed gas F2A and has undergone two-stage combustion, further flows in the X direction while exchanging heat with the water pipes 51, 52, 53 in the main body 40, and is exhausted from the exhaust stack 18 as exhaust gas.

By performing the two-stage combustion in this way, the boiler 1 according to the present embodiment can reduce the NOx amount and the CO amount contained in the combustion gas discharged from the can body 10. Here, in order to suppress the generation of CO by self-combusting the secondary fuel F2, it is preferable to keep the temperature at the supply position of the secondary fuel F2 high to some extent. However, if the temperature of the supply position of the secondary fuel F2 is made too high, the combustion temperature of the secondary fuel F2 (the maximum temperature reached by combustion) becomes too high, and the amount of NOx in the combustion gas may increase. .. Therefore, when performing the two-stage combustion in the boiler 1, it is preferable to keep the temperature in the can 10 within a predetermined range in order to suppress the NOx amount and the CO amount.

The boiler 1 according to the present embodiment keeps the temperature inside the can body 10 within a predetermined range by introducing the cooling fluid G0 into the can body 10. Since the cooling fluid G0 is a fluid that does not burn with the combustion gas and has a temperature lower than that of the combustion gas in the can body 10, the temperature in the can body 10 can be lowered. Here, a position in the can body 10 to which the cooling fluid G0 is supplied, in other words, a position in the can body 10 to which the secondary fuel supply line 74 is connected is defined as a supply position. The cooling line 26 reduces the temperature of the supply position by supplying the cooling fluid G0 to the supply position inside the can body 10. Here, the space in the can 10 between the supply position and the position on the X direction side of the supply position by a predetermined distance is referred to as a predetermined space. It can be said that the cooling line 26 reduces the temperature of the predetermined space by supplying the cooling fluid G0 to the supply position. In the first embodiment, the predetermined space is a space extending from the supply position where the secondary fuel F2 is supplied to the downstream side of the combustion gas. That is, the cooling line 26 reduces the temperature of the space in which the unburned component of the primary fuel F1 and the secondary fuel F2 or the secondary fuel F2 burn by supplying the cooling fluid G0 to the supply position. I can say. In other words, it can be said that the predetermined space is a space where at least the secondary fuel F2 of the primary fuel F1 and the secondary fuel F2 burns. In addition, in this embodiment, since the supply position is fixed, it can be said that the predetermined space is a space whose position is fixed in the can body 10, but the position does not move in the can body 10.

Thus, the boiler 1 reduces the temperature of the predetermined space in the can body 10 by introducing the cooling fluid G0 into the can body 10. Further, the boiler 1 maintains the temperature inside the can body 10 within a predetermined range by adjusting the amount of the cooling fluid G0 supplied by the control device 30. Hereinafter, the control device 30 will be described.

(Configuration of control device)
FIG. 3 is a schematic block diagram of the control device according to the first embodiment. As shown in FIG. 3, the control device 30 includes a control unit 80 and a storage unit 82. The control device 30 is a computer that controls the boiler 1. The storage unit 82 is a memory that stores the calculation content of the control unit 80, the program information, and the like. The storage unit 82 includes at least one external storage device such as a RAM (Random Access Memory), a ROM (Read Only Memory), and a flash memory (Flash Memory).

The control unit 80 is a computing device, that is, a CPU (Central Processing Unit). The controller 80 includes an air controller 84, a primary fuel controller 86, a secondary fuel controller 88, and a fluid controller 90. The air control unit 84, the primary fuel control unit 86, the secondary fuel control unit 88, and the fluid control unit 90 execute the processing described later by reading the software (program) stored in the storage unit 82. .. However, the air control unit 84, the primary fuel control unit 86, the secondary fuel control unit 88, and the fluid control unit 90 may each be configured by dedicated hardware circuits.

The air control unit 84 calculates the supply amount of the air A to be supplied to the can body 10, and controls the supply amount of the air A to be supplied to the can body 10 so that the calculated supply amount is obtained. Specifically, the air control unit 84, for example, according to the combustion stage instructed to the boiler 1, that is, in accordance with the instruction as to which combustion stage the boiler 1 is to be operated, the supply amount of the air A is supplied. To calculate. For example, in the present embodiment, information indicating the relationship between the combustion stage and the amount of air A is stored in the storage unit 82. The air control unit 84 reads this information from the storage unit 82 and substitutes the instructed combustion stage into this relationship to calculate the supply amount of the air A. For example, the supply amount of the air A is set to increase as the instructed combustion stage increases, that is, as the combustion increases. The method of calculating the supply amount of the air A is not limited to this, and may be set arbitrarily. Further, in the boiler 1 in the present embodiment, a plurality of combustion stages are set for each combustion amount, and for example, four of stop, low combustion, medium combustion, and high combustion are set.

The air control unit 84 controls the blower 12 so that the amount of air A calculated in this way is supplied. For example, the air control unit 84 supplies the calculated amount of air A to the duct 14 by adjusting the opening degree of a damper (not shown) provided on the upstream side of the pressure reducing member 12A shown in FIG. For example, the air control unit 84 acquires information on the differential pressure between the upstream side and the downstream side of the pressure reducing member 12A from the air differential pressure sensor 12B shown in FIG. The air control unit 84 acquires the amount of the air A actually supplied to the duct 14 from the information on the differential pressure detected by the air differential pressure sensor 12B, and calculates it based on the acquired actual supply amount of the air A. The opening degree of the damper is adjusted so that the amount of air A actually supplied is adjusted. The air control unit 84 is not limited to adjusting the opening degree of the damper when controlling the supply amount of the air A. For example, the air control unit 84 may control the supply amount of the air A by controlling the rotation speed of the blower 12 with an inverter, or may control the supply amount of the air A using both the inverter and the damper. You may.

The primary fuel control unit 86 calculates the supply amount of the primary fuel F1 supplied to the can body 10, and controls the supply amount of the primary fuel F1 supplied to the can body 10 so that the calculated supply amount is obtained. Specifically, the primary fuel control unit 86 calculates the target supply amount of the primary fuel F1 based on the supply amount of the air A to the duct 14. The primary fuel control unit 86 acquires information on the differential pressure between the upstream side and the downstream side of the pressure reducing member 12A from the air differential pressure sensor 12B shown in FIG. 1, and based on the acquired differential pressure information, air to the duct 14 is obtained. Acquire the supply amount of A. In addition, the primary fuel control unit 86 may acquire information on the supply amount of the air A from the air control unit 84. In the present embodiment, the storage unit 82 stores information indicating the relationship between the amount of air A and the amount of primary fuel F1. The primary fuel control unit 86 reads out information indicating the relationship between the amount of air A and the amount of primary fuel F1 from the storage unit 82, and substitutes the obtained supply amount of air A into this relationship, whereby the primary fuel F1 Calculate the target supply amount. As described above, the boiler 1 controls the primary fuel control unit 86 to supply the target supply amount of the primary fuel F1 calculated based on the information indicating the relationship between the amount of the air A and the amount of the primary fuel F1. However, the method of supplying the target supply amount of the primary fuel F1 is not limited to this. For example, in the boiler 1, a mechanical governor is provided in the fuel supply line 60, and the governor operates according to the differential pressure between the upstream side and the downstream side of the pressure reducing member 12A (that is, the differential pressure detected by the air differential pressure sensor 12B). The amount of primary fuel F1 may be controlled to be supplied by changing the amount. That is, the operation amount of the governor is set in association with the supply amount (differential pressure) of the air A, and the governor is operated according to the supply amount of the air A to supply the primary fuel F1 of the target supply amount. May be. The target supply amount of the primary fuel F1 is set so that the proportion of oxygen contained in the combustion gas after combustion of the primary fuel F1 is, for example, 6% or more and 10% or less, preferably about 8%. It is set. The proportion of oxygen contained in the combustion gas refers to the proportion of oxygen contained in the combustion gas with respect to the total quantity of the combustion gas. Further, the combustion gas after the combustion of the primary fuel F1 refers to the combustion gas in the state where the combustion reaction of the primary fuel F1 is completed, and the state where the combustion reaction of the primary fuel F1 is completed and the secondary fuel F2 is supplied. It can be said that it refers to the combustion gas in the state where it is not. It should be noted that the combustion reaction may continue even though it is extremely small in the above-mentioned "combustion gas in a state where the combustion reaction is completed". Therefore, "combustion reaction completion" means 100% of the combustion reaction. In some cases, that is, it does not mean that the combustion is completed. In addition, it can be said that the target supply amount of the primary fuel F1 is set so that the air ratio in the mixed gas F1A becomes a predetermined value. In this case, the air ratio is preferably 1.4 or more and 2.0 or less, for example. The target supply amount of the primary fuel F1 is not limited to the above description and may be calculated by any method.

The primary fuel control unit 86 controls the primary fuel supply unit 22 so that the target supply amount of the primary fuel F1 calculated in this way is supplied. Specifically, the primary fuel control unit 86 controls the opening degree of the primary fuel adjustment valve 62 to supply the calculated amount of the primary fuel F1 to the can body 10. In the present embodiment, the primary fuel control unit 86 acquires information on the differential pressure of the primary fuel F1 between the upstream side and the downstream side of the pressure reducing member 64 from the fuel differential pressure sensor 66, and based on this differential pressure information, actually Alternatively, the amount of the primary fuel F1 supplied to the can body 10 may be acquired. In this case, the primary fuel control unit 86 adjusts the opening degree of the primary fuel adjustment valve 62 so that the actually supplied amount of the primary fuel F1 becomes the target supply amount. The primary fuel control unit 86 is not limited to adjusting the opening degree of the primary fuel adjustment valve 62 when controlling the supply amount of the primary fuel F1. For example, the primary fuel control unit 86 may control the supply amount of the primary fuel F1 by a mechanical governor provided in the fuel supply line 60, or may use both the governor and the primary fuel adjustment valve 62. The supply amount of the primary fuel F1 may be controlled.

The secondary fuel control unit 88 calculates the supply amount of the secondary fuel F2 supplied to the can body 10, and controls the supply amount of the secondary fuel F2 supplied to the can body 10 so that the calculated supply amount is obtained. Specifically, the secondary fuel control unit 88 acquires information on the differential pressure of the primary fuel F1 between the upstream side and the downstream side of the pressure reducing member 64 from the fuel differential pressure sensor 66, and based on the acquired differential pressure information. , The supply amount of the primary fuel F1 to the can body 10 is acquired. Further, the secondary fuel control unit 88 may acquire information on the supply amount of the primary fuel F1 from the primary fuel control unit 86. Then, in the present embodiment, information indicating the relationship between the amount of the primary fuel F1 and the amount of the secondary fuel F2 is stored in the storage unit 82. The secondary fuel control unit 88 reads information indicating the relationship between the amount of the primary fuel F1 and the amount of the secondary fuel F2 from the storage unit 82, and substitutes the acquired supply amount of the primary fuel F1 into this relationship. The target supply amount of the secondary fuel F2 is calculated. The target supply amount of the secondary fuel F2 is set so that the proportion of oxygen contained in the combustion gas after combustion of the secondary fuel F2 is, for example, 2% or more and 6% or less, preferably about 4%. , Has been set. The combustion gas after combustion of the secondary fuel F2 refers to the combustion gas in a state where the combustion reaction of the secondary fuel F2 is completed. Furthermore, in other words, the combustion gas after the combustion of the secondary fuel F2 may be rephrased as the combustion gas in a state where the combustion reactions of both the primary fuel F1 and the secondary fuel F2 have been completed. It may be said that the combustion gas is exhaust gas (exhaust gas). It can also be said that the target supply amount of the secondary fuel F2 is set so that the air ratio when the mixed gas F1A and the mixed gas F2A are summed is a predetermined value. In this case, the air ratio is preferably 1.1 or more and 1.4 or less. The target supply amount of the secondary fuel F2 is not limited to the above description and may be calculated by any method.

In this way, the target supply amount of the secondary fuel F2 is set according to the supply amount of the primary fuel F1. When the supply amount of the primary fuel F1 is adjusted by the information on the pressure difference from the fuel pressure difference sensor 66, the supply of the secondary fuel F2 is also appropriately performed according to the supply amount of the primary fuel F1. However, the method of calculating the target supply amount of the secondary fuel F2 is not limited to this. For example, an oxygen concentration sensor is provided in the exhaust stack 18, and the secondary fuel control unit 88 detects the secondary fuel F2 according to the detection result of the oxygen concentration contained in the combustion gas in the exhaust stack 18 by the oxygen concentration sensor. The target supply amount of the secondary fuel F2 may be set so that the ratio of oxygen contained in the combustion gas after combustion becomes a predetermined ratio.

The secondary fuel control unit 88 controls the secondary fuel supply unit 24 so that the target supply amount of the secondary fuel F2 thus calculated is supplied. Specifically, the secondary fuel control unit 88 controls the opening degree of the secondary fuel adjustment valve 72 to supply the calculated amount of the secondary fuel F2 to the can body 10. Note that the secondary fuel control unit 88 is not limited to adjusting the opening degree of the secondary fuel adjustment valve 72 when controlling the supply amount of the secondary fuel F2. For example, the secondary fuel control unit 88 may control the supply amount of the secondary fuel F2 by a mechanical governor provided in the secondary fuel supply line 70, or may control the governor and the secondary fuel adjustment valve 72. Both may be used to control the supply amount of the secondary fuel F2.

It should be noted that the supply amount of the secondary fuel F2 can be said to be an amount that can consume up to about 4% of oxygen contained in the combustion gas by about 8%, and is proportional to the supply amount of the primary fuel F1. That is, the secondary fuel control unit 88 increases the supply amount of the secondary fuel F2 in proportion to the increase of the supply amount of the primary fuel F1.

The fluid control unit 90 controls the flow rate adjusting unit 28 to change the amount of the cooling fluid G0 supplied into the can body 10 according to the supply amount of the secondary fuel F2. More specifically, the fluid control unit 90 calculates the supply amount of the cooling fluid G0 supplied to the can body 10 and controls the supply amount of the cooling fluid G0 supplied to the can body 10 so that the calculated supply amount is obtained. To do. The fluid control unit 90 controls the flow rate adjusting unit 28 to supply the calculated supply amount of the cooling fluid G0 to the can body 10.

The fluid control unit 90 calculates the amount of the cooling fluid G0 supplied into the can body 10 based on the supply amount of the secondary fuel F2. Specifically, the fluid control unit 90 calculates the amount of the cooling fluid G0 with which the temperature of the predetermined space inside the can 10 falls within the predetermined temperature range. The predetermined temperature range is 800° C. or higher and 1200° C. or lower, and more preferably 1000° C. or higher and 1200° C. or lower. Further, as described above, the predetermined space is a space in which the unburned portion of the primary fuel F1 and the secondary fuel F2 or the secondary fuel F2 burn, so the fluid control unit 90 controls the flow rate adjusting unit 28. Therefore, it can be said that the flow rate of the cooling fluid G0 is adjusted so that the combustion temperature of the combustion by the primary fuel F1 and the secondary fuel F2 falls within the predetermined temperature range. In other words, it can be said that the fluid control unit 90 supplies the cooling fluid G0 for a flow rate capable of keeping the combustion temperature of the predetermined space within the predetermined temperature range. For example, in the present embodiment, the storage unit 82 stores information indicating the relationship between the amount of the secondary fuel F2 and the amount of the cooling fluid G0 that keeps the temperature of the predetermined space in the can body 10 within the predetermined temperature range. I remember it. The air control unit 84 reads this information from the storage unit 82 and substitutes the supply amount of the secondary fuel F2 into this relationship to calculate the supply amount of the cooling fluid G0. Since the supply position of the secondary fuel F2 (the connection position of the secondary fuel supply line 74) is provided at a position where the temperature of the combustion gas is 800° C. or higher, the fluid control unit 90 causes the temperature of the predetermined position to rise. It can be said that the amount of the cooling fluid G0 is controlled so that the temperature becomes 1200° C. or lower.

In this way, the fluid control unit 90 calculates the supply amount of the cooling fluid G0 to the can body 10 based on the supply amount of the secondary fuel F2. However, the method of calculating the supply amount of the cooling fluid G0 is not limited to this. For example, the fluid control unit 90 may calculate the supply amount of the cooling fluid G0 to the can body 10 based on the supply amount of the primary fuel F1, or the can based on the supply amount of the air A to the duct 14. The supply amount of the cooling fluid G0 to the body 10 may be calculated, or the supply amount of the cooling fluid G0 to the can body 10 may be calculated based on the combustion stage instructed to the boiler 1. .. In this case, for example, the fluid control unit 90 has information indicating the relationship between the amount of the primary fuel F1 and the cooling fluid G0, the information indicating the relationship between the amount of the air A and the amount of the cooling fluid G0, or the combustion. Information indicating the relationship between the stage and the amount of the cooling fluid G0 is stored in the storage unit 82. The fluid control unit 90 reads this information from the storage unit 82 and substitutes the supply amount of the primary fuel F1, the supply amount of the air A, or the combustion stage into this relationship to calculate the supply amount of the cooling fluid G0. .. Further, the boiler 1 may be provided with a nitrogen oxide concentration sensor in the exhaust stack 18, and calculate the supply amount of the cooling fluid G0 to the can body 10 based on the detection result of the nitrogen oxide concentration sensor. In this case, the fluid control unit 90 acquires information on the nitrogen oxide concentration of the cooling fluid G0 inside the exhaust stack 18 detected by the nitrogen oxide concentration sensor. Then, the fluid control unit 90 calculates the flow rate of the cooling fluid G0 in which the content of nitrogen oxides falls within a predetermined range, based on the acquired nitrogen oxide concentration. The fluid control unit 90 controls the flow rate adjusting unit 28 to supply the can body 10 with the calculated cooling flow amount G0 of cooling fluid.

As described above, the cooling fluid G0 can reduce the temperature of the combustion gas, and the more the supply amount of the cooling fluid G0 is, the more the temperature can be reduced. Here, the combustion temperature in the can 10 depends on the combustion amount, that is, the supply amount of the primary fuel F1, the secondary fuel F2, and the air A, but the supply amount of the secondary fuel F2 is the supply amount of the primary fuel F1. The supply amount of the primary fuel F1 is calculated based on the supply amount of the air A. That is, the supply amounts of the primary fuel F1, the secondary fuel F2, and the air A are related to each other. Therefore, it can be said that the combustion temperature in the can 10 depends on the supply amount of the primary fuel F1. Therefore, it can be said that the fluid control unit 90 changes the supply amount of the cooling fluid G0 according to the supply amount of the primary fuel F1 in order to maintain the temperature of the predetermined space within the predetermined temperature range. That is, the fluid control unit 90 increases the amount of the cooling fluid G0 to be supplied as the supply amount of the primary fuel F1 is larger, and decreases the amount of the cooling fluid G0 to be supplied as the supply amount of the primary fuel F1 is smaller. There is.

The supply amount of the cooling fluid G0 will be further described. FIG. 4 is a graph showing the relationship among the primary fuel amount, the secondary fuel amount, and the cooling fluid amount. In FIG. 4, the horizontal axis represents the supply amount of the primary fuel F1. The line segment L1 indicates the relationship between the supply amount of the primary fuel F1 and the supply amount of the secondary fuel F2. As indicated by the line segment L1, the secondary fuel control unit 88 linearly increases the supply amount of the secondary fuel F2 as the supply amount of the primary fuel F1 linearly increases. That is, the rate at which the flow rate of the secondary fuel F2 increases when the supply amount of the primary fuel F1 increases is substantially constant. The line segment L2 shows the relationship between the supply amount of the primary fuel F1 and the supply amount of the cooling fluid G0. As indicated by the line segment L2, when the supply amount of the primary fuel F1 linearly increases, the fluid control unit 90 increases the supply amount of the secondary fuel F2 in a downwardly convex quadratic curve shape. .. That is, the fluid control unit 90 increases the rate of increase in the supply amount of the cooling fluid G0 when the supply amount of the primary fuel F1 increases as the supply amount of the primary fuel F1 increases. It controls the supply amount of. In a high combustion state in which the supply amount of the primary fuel F1 is large, the temperature rise rate of the can 10 may increase. The fluid control unit 90 can appropriately suppress the temperature rise in the high combustion state by increasing the supply amount of the cooling fluid G0 in the high combustion state like the line segment L2.

The control device 30 is configured as described above. Next, a flow of a method for supplying fuel and the like by the control device 30 will be described based on a flowchart. FIG. 5 is a flowchart illustrating a control flow of the control unit according to the first embodiment. As shown in FIG. 5, first, the control unit 80 calculates the supply amount of the air A by the air control unit 84, and controls the blowing amount so that the calculated amount of the air A is supplied (step). S10). Then, the control unit 80 calculates the supply amount of the primary fuel F1 based on the supply amount of the air A by the primary fuel control unit 86 and supplies the calculated amount of the primary fuel F1 to the primary fuel adjustment valve 62. Is controlled (step S12). Then, the control unit 80 calculates the supply amount of the secondary fuel F2 based on the supply amount of the primary fuel F1 by the secondary fuel control unit 88 and supplies the calculated amount of the secondary fuel F2. The next fuel adjustment valve 72 is controlled (step S14). Then, the control unit 80 causes the fluid control unit 90 to cool the predetermined space within the can body 10 within a predetermined temperature range (for example, 800° C. or more and 1200° C. or less) based on the supply amount of the secondary fuel F2. The supply amount of G0 is calculated, and the flow rate adjusting unit 28 is controlled so that the calculated amount of the cooling fluid G0 is supplied (step S16). In this way, by supplying the primary fuel F1, the air A, the secondary fuel F2, and the cooling fluid G0, this processing ends.

In the description of FIG. 5, detection of the combustion stage, supply control of air A based on the combustion stage, supply control of primary fuel F1 based on the supply amount of air AA, and secondary fuel F2 based on the supply amount of primary fuel F1. The supply control and the supply control of the cooling fluid G0 based on the supply amount of the secondary fuel F2 are performed in this order. However, each control is not limited to be performed in this order. For example, the control device 30 includes information (table) indicating the relationship between the combustion stage and the supply amount of the air A, information indicating the relationship between the combustion stage and the supply amount of the primary fuel F1, and the combustion stage and the supply of the secondary fuel F2. Information indicating the relationship between the amounts and the information indicating the relationship between the combustion stage and the supply amount of the cooling fluid G0 may be stored in the storage unit 82 in advance. In this case, the control device 30 reads these pieces of information, and from the combustion stage instructed to the boiler 1, the supply amount of the air A, the supply amount of the primary fuel F1, the supply amount of the secondary fuel F2, and the cooling amount. The supply amount of the fluid G0 is calculated, and the air A, the primary fuel F1, the secondary fuel F2, and the cooling fluid G0 are supplied so that the calculated supply amount is obtained. After performing the supply control in this way, the control device 30 controls the supply of the primary fuel F1 based on the supply amount of the air A and the supply control of the secondary fuel F2 based on the supply amount of the primary fuel F1 as described above. The supply amount of the cooling fluid G0 may be controlled based on the supply amount of the secondary fuel F2 to finely adjust the supply amount.

As described above, the boiler 1 according to the present embodiment includes the can body 10 having the water pipes 51, 52, 53, the burner 16, the secondary fuel supply unit 24, the cooling line 26, and the flow rate adjusting unit 28. , And a control unit 80. The burner 16 is connected to the can body 10 and supplies the primary fuel F1 and the air A into the can body 10. The secondary fuel supply unit 24 supplies the secondary fuel F2 into the can body 10 on the downstream side of the burner 16 in the flow direction of the combustion gas. The cooling line 26 introduces a cooling fluid G0 that reduces the temperature of a predetermined space in the can body 10 on the downstream side of the burner 16 in the flow direction of the combustion gas. The flow rate adjusting unit 28 is provided in the cooling line 26, and can adjust the flow rate of the cooling fluid G0 introduced into the can body 10 from the cooling line 26. The control unit 80 controls the flow rate adjusting unit 28 to supply the flow rate of the cooling fluid G0 introduced into the can body 10 such that the temperature of the predetermined space is 800° C. or higher and 1200° C. or lower.

The boiler 1 according to the present embodiment suppresses the generation of CO by setting the temperature of the predetermined space in the can body 10 to 800° C. or higher. Further, the boiler 1 reduces the NOx by setting the temperature of the predetermined space in the can body 10 to 1200° C. or lower by the cooling fluid G0. Here, for example, in the case where the boiler 1 having a plurality of combustion stages as described above is in low combustion, if the combustion stage is changed from the required load and the combustion amount is increased, the temperature rise becomes large, It may be difficult to maintain the temperature in the predetermined space at 800°C to 1200°C. On the other hand, the boiler 1 according to the present embodiment can control the temperature in the predetermined space to 800°C to 1200°C by cooling with the cooling fluid G0. Therefore, according to the boiler 1, even if the combustion stage changes, the flow rate adjusting unit 28 is controlled to adjust the flow rate of the cooling fluid G0, so that NOx and CO can be appropriately reduced. Furthermore, the boiler 1 according to this embodiment may control the supply amount of the cooling fluid G0 according to the amount of the primary fuel F1, the secondary fuel F2, or the air A. In this case, in the boiler 1, for example, when the supply amount of the primary fuel F1, the secondary fuel F2, or the air A is small, the supply amount of the cooling fluid G0 becomes excessive and the temperature becomes too low, and the primary fuel F1 When the supply amount of the secondary fuel F2 or the air A is large, it is possible to prevent the supply amount of the cooling fluid G0 from becoming insufficient and the temperature becoming too high.

Further, the control unit 80 controls the flow rate adjusting unit 28 such that the larger the supply amount of the primary fuel F1 is, the higher the rate of increase of the flow rate of the cooling fluid G0 when the supply amount of the primary fuel F1 is increases. To do. By increasing the supply amount of the cooling fluid G0 in the high combustion state as described above, the boiler 1 can suitably suppress the temperature rise in the high combustion state.

The secondary fuel supply unit 24 (secondary fuel supply line 70) is connected to the cooling line 26, and supplies the secondary fuel F2 to the inside of the can body 10 in a state of being mixed with the cooling fluid G0. This boiler 1 supplies the secondary fuel F2 to the cooling body G0 in a state of being mixed with the cooling fluid G0, so that the temperature is raised by the cooling fluid G0 while preferably performing two-stage combustion with the secondary fuel F2. It is possible to suppress the passing.

However, the cooling line 26 may not be connected to the secondary fuel supply unit 24, and the secondary fuel F2 and the cooling fluid G0 may be separately supplied into the can body 10 without being mixed. .. In this case, the cooling line 26 is preferably connected to the can body 10 on the upstream side of the flow of the combustion gas with respect to the secondary fuel supply unit 24. That is, in this case, the cooling line 26 is connected to a position between the ignition means (not shown) and the secondary fuel supply unit 24 (secondary fuel supply line 74). Therefore, in this case, it can be said that the secondary fuel supply unit 24 supplies the secondary fuel F2 into the can body 10 on the downstream side of the cooling line 26 in the flow direction of the combustion gas. In this way, by supplying the secondary fuel F2 to the downstream side of the cooling fluid G0, it is possible to cool the combustion gas, slow the reaction with the secondary fuel F2, and suppress the temperature rise. Further, by supplying the secondary fuel F2 to the downstream side of the cooling fluid G0, that is, by supplying the cooling fluid G0 to the upstream side of the secondary fuel F2, the cooling fluid G0 causes the primary fuel F1 to flow. It is possible to block the flame of the combustion gas from going downstream. As a result, the flame of the combustion gas can be prevented from coming into contact with the secondary fuel F2, and the temperature rise due to the combustion of the secondary fuel F2 with the flame can also be suppressed.

The flow rate adjusting unit 28 is a fan that supplies the exhaust gas discharged from the inside of the can body 10 into the cooling line 26. Further, the cooling line 26 introduces the exhaust gas supplied from the flow rate adjusting unit 28 into the can body 10 as the cooling fluid G0. This boiler 1 can cool the inside of the can body 10 appropriately by using the exhaust gas as the cooling fluid G0. Furthermore, by introducing the exhaust gas into the can body 10, it also functions as EGR (Exhaust Gas Recirculation), and NOx can be reduced appropriately. Further, by using the flow rate adjusting unit 28 as a fan, the exhaust gas as the cooling fluid G0 can be suitably taken in, and the intake amount of the exhaust gas can also be suitably controlled.

However, the cooling fluid G0 is not limited to the exhaust gas, and may be any fluid as long as it is a fluid that can reduce the temperature inside the can body 10 raised by the combustion gas. More specifically, the cooling fluid G0 is a fluid that does not burn with the combustion gas and is preferably a fluid having a temperature lower than that of the combustion gas in the can 10. The cooling fluid G0 is preferably gas, but may be liquid. Examples of the cooling fluid G0 other than the exhaust gas include steam, water, or an inert gas. That is, the cooling line 26 may introduce at least one or more of exhaust gas, steam, water, and an inert gas discharged from the inside of the can body 10 into the can body 10 as the cooling fluid G0. .. By using such a cooling fluid G0, the temperature rise in the can body 10 can be suppressed appropriately. Note that examples of the inert gas include nitrogen, carbon dioxide, argon, and the like.

(Second embodiment)
Next, a second embodiment will be described. The boiler 1a according to the second embodiment shows an example in which steam is used as the cooling fluid. Descriptions of parts of the second embodiment that have the same configuration as the first embodiment will be omitted.

FIG. 6 is a schematic cross-sectional view of the boiler according to the second embodiment. As shown in FIG. 6, the boiler 1a according to the second embodiment has a cooling line 26a and a flow rate adjusting unit 28a. One end of the cooling line 26a is connected to the upper header 42 and the steam header (not shown), and the other end is connected to the secondary fuel supply line 70 via the ejector 76a. The cooling line 26a is supplied with the steam from the upper header 42 as a cooling fluid G0a. The cooling fluid G0a flowing through the cooling line 26a is supplied to the secondary fuel supply line 74 via the secondary fuel supply line 70, and is introduced into the can body 10 while being mixed with the secondary fuel F2. The flow rate adjusting unit 28a is an opening/closing valve that is opened/closed by the fluid control unit 90 of the control device 30. The flow rate adjusting unit 28a is controlled to open and close to adjust the supply amount of the cooling fluid G0a into the can body 10. Since the cooling fluid G0a is steam, the cooling line 26a does not have to be provided with a fan for taking in the cooling fluid G0a.

FIG. 7 is a schematic diagram of the ejector according to the second embodiment. As shown in FIG. 7, the ejector 76a has an inner cylinder 76a1 and an outer cylinder 76a2. The inner cylinder 76a1 is provided inside the outer cylinder 76a2. One end of the inner cylinder 76a1 is connected to the cooling line 26a, and the other end is tapered. The outer cylinder 76a2 has one end connected to the secondary fuel supply line 70 and the other end connected to the secondary fuel supply line 74. The cooling fluid G0a supplied from the cooling line 26a to the inner cylinder 76a1 is injected into the outer cylinder 76a2 from the inner cylinder 76a1 and flows from the outer cylinder 76a2 to the secondary fuel supply line 74. On the other hand, the secondary fuel F2 is sucked into the outer cylinder 76a2 from the secondary fuel supply line 70 by the injection of the cooling fluid G0a into the outer cylinder 76a2. The secondary fuel F2 sucked into the outer cylinder 76a2 flows from the outer cylinder 76a2 to the secondary fuel supply line 74 and is mixed with the cooling fluid G0a.

Even when steam is used as the cooling fluid G0a like the boiler 1a according to the second embodiment, NOx and CO can be appropriately reduced as in the first embodiment. Further, the boiler 1a according to the second embodiment has an ejector 76a connected to the cooling line 26a through which the cooling fluid G0a flows and the secondary fuel supply line 70 through which the secondary fuel F2 flows. The ejector 76a sucks the secondary fuel F2 from the secondary fuel supply line 70 by injecting the cooling fluid G0a from the cooling line 26a into the inside, and connects the secondary fuel F2 and the cooling fluid G0a. To the secondary fuel supply line 74. As described above, the boiler 1a has the ejector 76a that takes in the secondary fuel F2 by utilizing the vapor pressure of the cooling fluid G0a, so that the secondary fuel F2 is appropriately supplied even when the supply pressure of the secondary fuel F2 is low. And can be mixed with the cooling fluid G0a. It is also possible to carry out secondary combustion using, for example, steam with low dryness.

1, 1a... Boiler, 10... Can body, 12... Blower, 12A... Pressure reducing member, 12B... Air differential pressure sensor, 14... Duct, 16... Burner, 18... Exhaust pipe, 20... Fuel supply section, 22... Primary fuel Supply unit, 24... Secondary fuel supply unit, 26, 26a... Cooling line, 28, 28a... Flow rate adjusting unit, 30... Control device, 40... Main body unit, 42... Upper header, 44... Lower header, 50... Water pipe group , 51, 52, 53... Water pipe, 54... Connection wall, 60... Fuel supply line, 62... Primary fuel regulating valve, 64... Pressure reducing member, 66... Fuel differential pressure sensor, 70, 74... Secondary fuel supply line, 72 ... secondary fuel regulating valve, 76a... ejector, 76a1... inner cylinder, 76a2... outer cylinder, 80... control unit, 82... storage unit, 84... air control unit, 86... primary fuel control unit, 88... secondary fuel control Part, 90... Fluid control part, A... Air, F... Fuel, F1... Primary fuel, F1A, F2A... Mixed gas, F2... Secondary fuel, G0, G0a... Cooling fluid, L1, L2... Line segment, S … Combustion promotion space.

Claims (7)

A can body having a water pipe,
A burner connected to the can body and supplying primary fuel and air into the can body;
A secondary fuel supply unit that supplies a secondary fuel into the can body on the downstream side of the burner in the flow direction of combustion gas;
A cooling line that introduces a cooling fluid that reduces the temperature of a predetermined space inside the can on the downstream side of the burner in the flow direction of the combustion gas,
A flow rate adjusting unit provided in the cooling line, capable of adjusting the flow rate of the cooling fluid introduced into the can body from the cooling line,
A control unit that controls the flow rate adjusting unit and supplies a flow rate of the cooling fluid that is introduced into the can body such that the temperature of the predetermined space is 800° C. or higher and 1200° C. or lower;
Having a boiler. The control unit controls the flow rate adjusting unit so that the larger the supply amount of the primary fuel is, the higher the rate of increase in the flow rate of the cooling fluid when the supply amount of the primary fuel is,
The boiler according to claim 1. The secondary fuel supply unit is connected to the cooling line, and supplies the secondary fuel into the can body while being mixed with the cooling fluid.
The boiler according to claim 1 or 2. The secondary fuel supply unit supplies the secondary fuel into the can body on the downstream side of the cooling line in the flow direction of combustion gas,
The boiler according to any one of claims 1 to 3. The cooling line introduces at least one or more of exhaust gas discharged from the can body, steam, water, and an inert gas into the can body as the cooling fluid.
The boiler according to any one of claims 1 to 4. The flow rate adjusting unit is a fan that supplies the exhaust gas discharged from the can body into the cooling line,
The cooling line introduces the exhaust gas supplied from the flow rate adjusting unit into the can body as the cooling fluid.
The boiler according to claim 3. A can body having a water pipe, a burner that is connected to the can body and supplies primary fuel and air into the can body, and a secondary fuel in the can body downstream of the burner in the flow direction of combustion gas. Is provided in the cooling line, and a secondary fuel supply unit that supplies the cooling fluid, a cooling line that introduces a cooling fluid that reduces the temperature of a predetermined space inside the can downstream of the burner in the flow direction of the combustion gas, and the cooling line. A flow rate adjusting unit capable of adjusting the flow rate of the cooling fluid introduced into the can body from the cooling line,
The flow rate adjusting unit is controlled to supply the flow rate of the cooling fluid introduced into the can body such that the temperature of the predetermined space is 800° C. or higher and 1200° C. or lower.
Boiler control method.

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