Boiler system and control method for boiler

Abstract

To appropriately operate a soot blower in accordance with a state of a furnace, such as an adhesion amount of clinker adhering to a heat transfer pipe.SOLUTION: In a control method for a boiler, the boiler includes: a furnace comprising a furnace wall having a plurality of heat transfer pipes in which fluid flows; a combustion apparatus that generates combustion gas by injecting solid fuel and combustion air to the furnace; and a plurality of soot blowers that injects steam to surfaces of the heat transfer pipes and enables switching between an insertion state of being inserted in the furnace and a pulling-out state of being pulled out from the furnace. The control method for the boiler includes: a temperature detection process S102 of detecting temperature of the plurality of heat transfer pipes by using a plurality of temperature detection sections; and a control process S104 of controlling the predetermined soot blower on the basis of a plurality of first temperature detection values detected by the plurality of temperature detection sensors in a first period when the predetermined soot blower starts steam injection in the insertion state.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present disclosure relates to a boiler system and a method for controlling a boiler. [Background technology]

[0002] Boilers that burn solid fuels such as pulverized coal inject powdered solid fuel from a fuel burner into a furnace and burn it in the furnace. The boiler is provided with many heat transfer tubes that constitute a superheater and a reheater, and ash and the like burned during boiler operation adheres to the heat transfer tubes as clinker. If the boiler continues to operate with clinker adhering to the heat transfer tubes, the heat exchange efficiency of the heat transfer tubes decreases. For this reason, a soot blower is periodically operated to remove the clinker adhering to the heat transfer tubes (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3615776 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, the operation interval of the soot blower is fixed, so the soot blower cannot be operated appropriately according to the amount of clinker adhering to each heat transfer tube. Even if there is a bias in the amount of clinker adhering to each heat transfer tube, the soot blower operates at a fixed operation interval.

[0005] The present disclosure has been made in consideration of the above circumstances, and aims to provide a boiler system and a boiler control method that are capable of appropriately operating a soot blower depending on the condition of the furnace, such as the amount of clinker adhering to the heat transfer tubes. [Means for solving the problem]

[0006] A boiler system according to one embodiment of the present disclosure comprises a boiler and a control unit that controls the boiler, wherein the boiler has a furnace composed of a furnace wall having a plurality of heat transfer tubes through which a fluid flows, a combustion device that injects solid fuel and combustion air into the furnace to generate combustion gas, a plurality of soot blowers that inject steam onto the surface of the heat transfer tubes and are switchable between an inserted state in which they are inserted into the furnace and an extracted state in which they are extracted from the furnace, and a plurality of temperature detection units that detect the temperatures of the plurality of heat transfer tubes, and the control unit controls the operation of a predetermined soot blower based on a plurality of first temperature detection values ​​detected by the plurality of temperature detection units during a first period after a predetermined soot blower starts steam injection to inject steam in the inserted state.

[0007] In a boiler control method according to one embodiment of the present disclosure, the boiler has a furnace composed of a furnace wall having a plurality of heat transfer tubes through which a fluid flows, a combustion device that injects solid fuel and combustion air into the furnace to generate combustion gas, and a plurality of soot blowers that inject steam onto the surface of the heat transfer tubes and are switchable between an inserted state in which they are inserted into the furnace and an extracted state in which they are extracted from the furnace, and the method includes a temperature detection process for detecting the temperatures of the plurality of heat transfer tubes using a plurality of temperature detection units, and a control process for controlling the operation of a predetermined soot blower based on a plurality of first temperature detection values ​​detected by the plurality of temperature detection units during a first period after a predetermined soot blower starts steam injection to inject steam in the inserted state. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a boiler system and a boiler control method capable of appropriately operating a soot blower depending on the condition of the furnace, such as the amount of clinker adhering to the heat transfer tube. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram showing a boiler system according to an embodiment of the present disclosure. [Diagram 2]FIG. 1 is a perspective view of a furnace according to an embodiment of the present disclosure. [Diagram 3] 3 is a cross-sectional view taken along the line CC of the lower region of the furnace wall shown in FIG. 2. [Figure 4] FIG. 2 is a diagram showing a schematic structure of a soot blower. [Diagram 5] FIG. 4 is a front view of the lower region of the furnace shown in FIG. 3, seen from the front wall side. [Figure 6] FIG. 4 is a rear view of the lower region of the furnace shown in FIG. 3, seen from the rear wall side. [Figure 7] FIG. 4 is a right side view of the lower region of the furnace shown in FIG. 3, as viewed from the right wall side. [Figure 8] FIG. 4 is a left side view of the lower region of the furnace shown in FIG. 3, seen from the left wall side. [Figure 9] 1 is a graph showing the operating state of a soot blower and the change in temperature of a heat transfer tube over time. [Figure 10] 11 is a diagram showing, in sections A to D, differential temperature values ​​between maximum and minimum temperature values ​​detected by a plurality of temperature detection units when the soot blower is operated. FIG. [Figure 11] 13 is a diagram showing, in the form of a grayscale image, the difference temperature value between the maximum temperature value and the minimum temperature value detected by multiple temperature detection units when the soot blower is operated. [Figure 12] 10 is a flowchart showing an operation for setting a predetermined soot blower operation interval. [Figure 13] 10 is a flowchart showing a process for operating a predetermined soot blower at a set operation interval. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to this embodiment, and when there are multiple embodiments, the present invention also includes a configuration in which each embodiment is combined. In the following description, up and above refer to the upper side in the vertical direction, and down and below refer to the lower side in the vertical direction, and the vertical direction is not precise and includes an error.

[0011] 1 shows a boiler system 100 including a boiler 10 using pulverized fuel of this embodiment as a main fuel. The boiler system 100 includes the boiler 10 and a control unit 50 that controls the boiler 10. The boiler 10 of this embodiment is a boiler that can burn pulverized fuel made of pulverized solid fuel in a combustion device and exchange heat generated by this combustion with feed water or steam to generate superheated steam. Biomass fuel, coal, etc. are used as the solid fuel.

[0012] The boiler 10 has a furnace 11, a combustion device 20, and a combustion gas passage 12. The furnace 11 has a hollow rectangular cylinder shape and is installed vertically. The furnace 11 is formed by a furnace wall 101 that serves as the inner wall surface. The furnace wall 101 is composed of a plurality of heat transfer tubes through which fluids (water, steam) flow, and fins that connect the heat transfer tubes. The furnace wall 101 recovers heat generated by the combustion of pulverized fuel by heat exchange with the water and steam flowing inside the heat transfer tube. The heat transfer tube suppresses the temperature rise of the furnace wall 101.

[0013] The combustion device 20 is a device that generates combustion gas by injecting solid fuel and combustion air into the furnace 11. The combustion device 20 is installed in the lower region 101A of the furnace 11. In this embodiment, the combustion device 20 has a plurality of burners 21A, 21B, 21C, 21D, 21E, and 21F (hereinafter, when there is no need to distinguish between these burners, they will be simply referred to as "burners 21") attached to the furnace wall 101.

[0014] The burners 21 are arranged at equal intervals in the furnace width direction along the furnace wall 101 (for example, arranged in the furnace width direction so as to face each of the opposing furnace walls 101 for opposed combustion), and are arranged in multiple tiers along the vertical direction. The shape of the furnace, the number of burner tiers, the number of burners in one tier, the arrangement of the burners, and the like are not limited to this embodiment.

[0015] Burners 21A, 21B, 21C, 21D, 21E, and 21F are respectively connected to a plurality of mills (pulverizers) 31A, 31B, 31C, 31D, 31E, and 31F (hereinafter, when there is no need to distinguish between these mills, they will be simply referred to as "mills 31") via a plurality of pulverized fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F (hereinafter, when there is no need to distinguish between these mills, they will be simply referred to as "mills 31").

[0016] The mill 31 is, for example, a vertical roller mill in which a grinding table (not shown) is supported inside so as to be rotatable, and a plurality of grinding rollers (not shown) are supported above the grinding table so as to be rotatable in conjunction with the rotation of the grinding table. The solid fuel ground by the cooperation of the grinding rollers and the grinding table is transported to a classifier (not shown) provided in the mill 31 by primary air (carrier gas, oxidizing gas) supplied to the mill 31.

[0017] In the classifier, the fuel particles are classified into pulverized fuel having a particle size equal to or smaller than that suitable for combustion in the burner 21, and coarse pulverized fuel having a particle size larger than that. The pulverized fuel passes through the classifier and is supplied to the burner 21 together with primary air via the pulverized fuel supply pipe 22. The coarse pulverized fuel that does not pass through the classifier falls onto the grinding table by its own weight inside the mill 31 and is re-ground.

[0018] An air register 23 is provided on the outside of the furnace 11 at the mounting position of the burner 21, and one end of an air duct 24 is connected to the air register 23. A forced draft fan (FDF) 32 is connected to the other end of the air duct 24. Air supplied from the forced draft fan 32 is heated by an air preheater 42 installed in the air duct 24, and is supplied to the burner 21 via the air register 23 as secondary air (combustion air, oxidizing gas), and is introduced into the furnace 11.

[0019] The combustion gas passage 12 is connected to the vertical upper part of the furnace 11. In the combustion gas passage 12, superheaters 102A, 102B, and 102C (hereinafter, when the superheaters are not distinguished from each other, they will be simply referred to as "superheaters 102"), reheaters 103A and 103B (hereinafter, when the reheaters are not distinguished from each other, they will be simply referred to as "reheaters 103"), and a coal economizer 104 are provided as heat exchangers for recovering heat from the combustion gas, and heat is exchanged between the combustion gas generated in the furnace 11 and the feed water or steam flowing inside each heat exchanger. The arrangement and shape of each heat exchanger are not limited to the form shown in FIG. 1.

[0020] A flue 13 is connected to the downstream side of the combustion gas passage 12, and discharges the combustion gas whose heat has been recovered by the heat exchanger. An air preheater (air heater) 42 is provided between the flue 13 and the air duct 24, and heat is exchanged between the air flowing through the air duct 24 and the combustion gas flowing through the flue 13, thereby heating the primary air supplied to the mill 31 and the secondary air supplied to the burner 21, thereby recovering further heat from the combustion gas after heat exchange with water and steam.

[0021] Furthermore, a denitration device 43 may be provided in the flue 13 at a position upstream of the air preheater 42. The denitration device 43 supplies a reducing agent having an effect of reducing nitrogen oxides, such as ammonia or urea water, to the combustion gas flowing through the flue 13, and promotes a reaction between the nitrogen oxides (NOx) in the combustion gas to which the reducing agent has been supplied and the reducing agent by the catalytic action of a denitration catalyst provided in the denitration device 43, thereby removing and reducing the nitrogen oxides in the combustion gas.

[0022] A gas duct 41 is connected to the flue 13 downstream of the air preheater 42. The gas duct 41 is provided with environmental equipment such as a dust collector 44, such as an electrostatic precipitator, for removing ash and the like from the combustion gas, a desulfurization equipment 46 for removing sulfur oxides, and an induced draft fan (IDF) 45 for directing the exhaust gas to these environmental equipment. The downstream end of the gas duct 41 is connected to a chimney 47, and the combustion gas treated in the environmental equipment is discharged to the outside of the system as exhaust gas.

[0023] When pulverized fuel is burned in the boiler 10, a plurality of mills 31 are driven to pulverize the solid fuel, and the pulverized fuel classified by a classifier is supplied together with primary air to the burner 21 via the pulverized fuel supply pipe 22. Secondary air heated by an air preheater 42 is supplied to the burner 21 from an air duct 24 via an air box 23. The burner 21 blows a pulverized fuel mixture, which is a mixture of the pulverized fuel and the primary air, into the furnace 11, and also blows secondary air into the furnace 11.

[0024] The pulverized fuel mixture injected into the furnace 11 ignites and reacts with the secondary air to form a flame. The flame is formed in the lower region of the furnace 11, and high-temperature combustion gas rises inside the furnace 11 and flows into the combustion gas passage 12. In this embodiment, air is used as the oxidizing gas (primary air, secondary air), but the oxidizing gas may have a higher or lower oxygen content than air. By adjusting the ratio of the amount of oxygen to the amount of fuel supplied to an appropriate range, stable combustion is achieved in the furnace 11.

[0025] Moreover, above the mounting position of the burner 21 of the furnace 11, a plurality of additional air ports (AA ports) 25 for supplying additional air for combustion (AA) into the furnace 11 are provided. An end of an additional air duct (AA duct) 26 branched off from the air duct 24 is connected to the additional air port 25, and a part of the air supplied from the forced draft fan 32 can be supplied to the additional air port 25 via the additional air duct 26 as additional air for combustion.

[0026] In region A (corresponding to the installation range of the wind box 23 in the height direction) inside the furnace 11 shown in FIG. 1, a flame is formed by the combustion of a mixture of primary air and pulverized fuel with secondary air. Here, the air ratio in region A is set to be 1 or less, specifically, the amount of air (total amount of primary air and secondary air) supplied to the burner 21 is set to be less than the theoretical amount of air for the amount of fuel supplied to the burner 21, so that region A and region B (region between the top of the burner 21 and the bottom of the additional air port 25) inside the furnace 11 become reducing atmospheres, and nitrogen oxides (NOx) generated by combustion are reduced inside the furnace 11. After that, in region C (region above the bottom of the additional air port 25), additional air for combustion is supplied from the additional air port 25 to the combustion gas in which NOx has been reduced, and the combustion is completed, but the amount of NOx generated is reduced by the amount of the reduction effect in region A and region B.

[0027] The combustion gas flowing into the combustion gas passage 12 exchanges heat with water and steam in a superheater 102, a reheater 103, and a coal economizer 104 arranged inside the combustion gas passage 12, and is then discharged into the flue 13, where nitrogen oxides are removed in a denitration device 43, and the combustion gas exchanges heat with primary air and secondary air in an air preheater 42, and is then discharged into a gas duct 41, where ash and the like are removed in a dust collector 44, and sulfur oxides are removed in a desulfurization device 46, and the combustion gas is then discharged to the outside of the system from a chimney 47. Note that the arrangement of the heat exchangers in the combustion gas passage 12 and the devices from the flue 13 to the gas duct 41 with respect to the combustion gas flow does not necessarily have to be in the order described above.

[0028] The control unit 50 is a device that controls each part of the boiler 10. The control unit 50 is composed of, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in the storage medium or the like in the form of a program, for example, and the CPU reads this program into the RAM or the like and executes information processing and arithmetic processing to realize various functions.

[0029] The program may be installed in advance in a ROM or other storage medium, may be provided in a state stored in a computer-readable storage medium, may be distributed via wired or wireless communication means, etc. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, etc.

[0030] Next, a temperature detection sensor (temperature detection unit) 60 for detecting the temperature of the furnace wall 101 will be described with reference to Fig. 2 to Fig. 4. Fig. 2 is a perspective view showing a furnace 11 according to an embodiment of the present disclosure. Fig. 3 is a cross-sectional view of the lower region 101A of the furnace wall 101 shown in Fig. 2 taken along the CC arrow.

[0031] 2, the furnace 11 of this embodiment is formed by a furnace wall 101 having a lower region 101A and an upper region 101B. The furnace wall 101 has a front wall 101a to which the burners 21D, 21E, and 21F of the combustion device 20 are attached, a rear wall 101b to which the burners 21A, 21B, and 21C of the combustion device 20 are attached, a right wall 101c which is the right side of the furnace 11, and a left wall 101d which is the left side of the furnace 11.

[0032] In FIG. 2, reference symbols 21Aa, 21Ba, 21Ca, 21Da, 21Ea, and 21Fa indicate positions where burners 21A, 21B, 21C, 21D, 21E, and 21F are attached, respectively.

[0033] 2, in the lower region 101A of the furnace wall 101, the heat transfer tube 101C is formed so as to extend in a direction inclined with respect to the vertical direction VD. The heat transfer tube 101C is formed in a spiral shape that turns in the order of the front wall 101a, the right side wall 101c, the rear wall 101b, and the left side wall 101d as it moves along the vertical direction VD. The heat transfer tube 101C may be formed on each of the front wall 101a, the right side wall 101c, the rear wall 101b, and the left side wall 101d so as to extend along the vertical direction VD.

[0034] 2, the heat transfer tubes 101C are formed to extend along the vertical direction VD in the upper region 101B of the furnace wall 101. The heat transfer tubes 101C in the lower region 101A and the heat transfer tubes 101C in the upper region 101B are connected at a connection position between the lower region 101A and the upper region 101B so that a fluid (water, steam) flows continuously between them.

[0035] 3, the boiler 10 of this embodiment has a plurality of temperature detection sensors 60 for detecting the temperature of the heat transfer tubes 101C in the lower region 101A where the combustion device 20 is attached in the furnace wall 101. The temperature detection sensor 60 for detecting the temperature T [°C] of the lower region 101A is attached to the lower region 101A of the furnace wall 101 where the burners 21A, 21B, 21C, 21D, 21E, and 21F of the combustion device 20 are attached.

[0036] As shown in FIG. 3, the boiler 10 has multiple temperature detection sensors (temperature detection units) 60a, 60b, 60c, 60d, 60e, 60f, 60g, 60h, 60i, 60j, 60k, 60l, 60m, 60n, 60o, 60p, 60q, 60r, 60s, and 60t (hereinafter also referred to as temperature detection sensors 60).

[0037] Next, the soot blower 70 provided in the boiler 10 of this embodiment will be described with reference to Fig. 4. The soot blower 70 shown in Fig. 4 is a device that injects steam onto the surface of the heat transfer tube 101C and removes clinker attached to the surface of the heat transfer tube 101C and the inner wall surface of the furnace wall 101. The boiler 10 has a plurality of soot blowers 70 attached to the front wall 101a, the rear wall 101b, the right side wall 101c, and the left side wall 101d, respectively. Note that the soot blower 70 shown in Fig. 4 is disposed on the furnace wall 101 of the furnace 11, but may be in other forms. For example, the soot blower 70 may be disposed in the combustion gas passage 12 in which the superheater 102, the reheater 103, and the economizer 104 are disposed.

[0038] As shown in Fig. 4, the soot blower 70 includes a nozzle block 71 having spray holes 71a and 71b, a soot blower tube 72 whose tip is connected to the nozzle block 71, and a motor 73. The motor 73 and the soot blower tube 72 are connected via a power transmission mechanism (not shown) such as gears, and rotation of the motor 73 enables the soot blower tube 72 to rotate about its central axis and move in the direction of the central axis. The soot blower 70 is switchable between an inserted state shown by a solid line in which the nozzle block 71 is inserted into the furnace 11, and a withdrawn state shown by a dotted line in which the nozzle block 71 is withdrawn to the outside of the furnace 11.

[0039] The motor 73 is driven based on a command from the control unit 50. The rear end of the soot blower tube 72 is connected to a spray steam supply line 74. The soot blower 70 circulates steam at a pressure adjusted by a steam pressure control valve 75 through the soot blower tube 72, and sprays the steam from the spray holes 71a, 71b into the furnace 11. By spraying the steam from the spray holes 71a, 71b onto the heat transfer tube 101C, clinker adhering to the heat transfer tube 101C is removed.

[0040] Next, the soot blower 70 attached to the furnace wall 101 will be described with reference to Figures 5 to 8. In Figures 5 to 8, the horizontal direction is indicated by HD, and the vertical direction is indicated by VD. Note that the positions and numbers of the multiple soot blowers 70 shown in Figures 5 to 8 are merely examples, and the positions and numbers may be different from those shown in Figures 5 to 8.

[0041] Fig. 5 is a front view of the lower region 101A of the furnace 11 shown in Fig. 3 as seen from the front wall 101a side. As shown in Fig. 5, soot blowers 70F1a, 70F3a, 70F5a, 70F2b, 70F4b, 70F6b, 70F1c, 70F3c, 70F5c, 70F2d, 70F4d, and 70F6d are attached to the front wall 101a. Soot blowers 70F1a, 70F3a, 70F5a, 70F2b, 70F4b, 70F6b, 70F1c, 70F3c, 70F5c, 70F2d, 70F4d, and 70F6d are mounted so as to move forward and backward along axes Y1a, Y3a, Y5a, Y2b, Y4b, Y6b, Y1c, Y3c, Y5c, Y2d, Y4d, and Y6d, respectively.

[0042] Fig. 6 is a front view of the lower region 101A of the furnace 11 shown in Fig. 3 as seen from the rear wall 101b side. As shown in Fig. 6, soot blowers 70B6a, 70B4a, 70B2a, 70B5b, 70B3b, 70B1b, 70B6c, 70B4c, 70B2c, 70B5d, 70B3d, and 70B1d are attached to the rear wall 101b. Soot blowers 70B6a, 70B4a, 70B2a, 70B5b, 70B3b, 70B1b, 70B6c, 70B4c, 70B2c, 70B5d, 70B3d, and 70B1d are mounted so as to move forward and backward along axes Y6a, Y4a, Y2a, Y5b, Y3b, Y1b, Y6c, Y4c, Y2c, Y5d, Y3d, and Y1d, respectively.

[0043] The axes Y1a, Y1b, Y1c, and Y1d are disposed at the position of the axis Y1 shown in FIG. 3. The axes Y2a, Y2b, Y2c, and Y2d are disposed at the position of the axis Y2 shown in FIG. 3. The axes Y3a, Y3b, Y3c, and Y3d are disposed at the position of the axis Y3 shown in FIG. 3. The axes Y4a, Y4b, Y4c, and Y4d are disposed at the position of the axis Y4 shown in FIG. 3. The axes Y5a, Y5b, Y5c, and Y5d are disposed at the position of the axis Y5 shown in FIG. 3. The axes Y6a, Y6b, Y6c, and Y6d are disposed at the position of the axis Y6 shown in FIG. 3.

[0044] Fig. 7 is a front view of the lower region 101A of the furnace 11 shown in Fig. 3 as seen from the right side wall 101c side. As shown in Fig. 7, soot blowers 70R1a, 70R3a, 70R2b, 70R4b, 70R1c, 70R3c, 70R2d, and 70R4d are attached to the right side wall 101c. The soot blowers 70R1a, 70R3a, 70R2b, 70R4b, 70R1c, 70R3c, 70R2d, and 70R4d are attached so as to move forward and backward along axes X1a, X3a, X2b, X4b, X1c, X3c, X2d, and X4d, respectively.

[0045] Fig. 8 is a front view of the lower region 101A of the furnace 11 shown in Fig. 3 as seen from the left side wall 101d side. As shown in Fig. 8, soot blowers 70L4a, 70L2a, 70L3b, 70L1b, 70L4c, 70L2c, 70L3d, and 70L1d are attached to the left side wall 101d. The soot blowers 70L4a, 70L2a, 70L3b, 70L1b, 70L4c, 70L2c, 70L3d, and 70L1d are attached so as to advance and retreat along axes X4a, Y2a, X3b, X1b, X4c, X2c, X3d, and X1d, respectively.

[0046] The axes X1a, X1b, X1c, and X1d are disposed at the position of the axis X1 shown in Figure 3. The axes X2a, X2b, X2c, and X2d are disposed at the position of the axis X2 shown in Figure 3. The axes X3a, X3b, X3c, and X3d are disposed at the position of the axis X3 shown in Figure 3. The axes X4a, X4b, X4c, and X4d are disposed at the position of the axis X4 shown in Figure 3.

[0047] The control unit 50 controls the multiple soot blowers 70 attached to the front wall 101a, rear wall 101b, right side wall 101c, and left side wall 101d of the furnace wall 101 to switch between an inserted state and a withdrawn state independently. FIG. 9 is a graph showing the operating state of the soot blower 70 and the temperature change over time of the heat transfer tube. The stopped state is a state in which the nozzle block 71 of the soot blower 70 is in a withdrawn state in which it is withdrawn from the furnace 11 and the driving of the motor 73 is stopped. The operating state is a state in which the motor 73 is driven to move the nozzle block 71 from the withdrawn state to the inserted state, steam is sprayed from the nozzle block 71, and then the nozzle block 71 is moved from the inserted state to the withdrawn state.

[0048] As shown in Fig. 9, the control unit 50 switches a certain soot blower 70 to an operating state at time t1 after keeping it in a stopped state from time t0 to time t1. From time t1, the control unit 50 drives the motor 73 to move the soot blower tube 72 from the position shown by the dotted line in Fig. 4 to the position shown by the solid line, switching the soot blower 70 from the withdrawn state to the inserted state.

[0049] In response to the soot blower insertion operation, the control unit 50 opens the steam pressure control valve 75 and sprays steam from the spray holes 71a, 71b into the furnace 11. In response to the soot blower withdrawal operation, the control unit 50 closes the steam pressure control valve 75 and stops the spraying of steam from the spray holes 71a, 71b. Thereafter, the control unit 50 drives the motor 73 from the completion of spraying until time t3 to move the soot blower tube 72 from the position shown by the solid line in Figure 4 to the position shown by the dotted line, and switches the soot blower 70 from the inserted state to the withdrawn state.

[0050] 4 is configured to switch between an open state in which steam is sprayed from the spray holes 71a, 71b into the furnace 11 and a closed state in which steam is not sprayed from the spray holes 71a, 71b into the furnace 11 by a steam pressure regulating valve 75 arranged in the spray steam supply line 74, but other configurations are also possible. For example, a stop valve may be arranged inside the soot blower tube 72, and the stop valve may be used to switch between the open state and the closed state.

[0051] During the soot blower operation period, steam is sprayed from the spray holes 71a and 71b onto the heat transfer tube 101C to remove clinker adhering to the heat transfer tube 101C. As the clinker is removed, the heat transfer performance of the heat transfer tube 101C increases, and the temperature of the heat transfer tube 101C detected by the temperature detection sensor 60 increases as shown in FIG.

[0052] The control unit 50 detects the maximum temperature value (first temperature detection value) T1 detected by the temperature detection sensor 60 during a first period PR1 from time t2 during steam injection from the spray holes 71a, 71b to time t3 when the soot blower 70 is stopped. The control unit 50 also detects the minimum temperature value (second temperature detection value) T2 detected by the temperature detection sensor 60 during a second period PR2 from time t1 when the soot blower 70 is started to time t2.

[0053] The control unit 50 calculates a differential temperature value Tdif, which is the difference obtained by subtracting the temperature value T2 from the temperature value T1. The differential temperature value Tdif is a value indicating the degree of increase in the thermal conductivity of the heat transfer tube 101C due to the removal of clinker adhering to the heat transfer tube 101C. The larger the differential temperature value Tdif, the greater the amount of clinker removed. The larger the differential temperature value Tdif calculated when a specified soot blower 70 is operated, the greater the amount of clinker removed when a specified soot blower 70 is operated.

[0054] Therefore, when operating a specified soot blower 70 to perform steam injection to inject steam onto the surface of the heat transfer tube 101C, it is effective to calculate a differential temperature value Tdif from the temperature values ​​T1, T2 detected by multiple temperature detection sensors 60, and control the operation of the specified soot blower 70 in accordance with the differential temperature value Tdif.

[0055] For example, by shortening the operating interval at which a given soot blower 70 performs steam injection as the differential temperature value Tdif becomes higher, the soot blower 70 can be operated appropriately according to the condition of the furnace 11 so as to remove clinker from areas where clinker accumulates in large amounts.

[0056] Here, an example of the differential temperature value Tdif calculated from the temperature values ​​T1, T2 detected by the plurality of temperature detection sensors 60 when a certain soot blower 70 performs steam injection will be described with reference to the drawings. Fig. 10 is a diagram showing, in sections A to D, the differential temperature value Tdif between the maximum temperature value T1 and the minimum temperature value T2 detected by the plurality of temperature detection sensors 60 when the soot blower 70 is operated.

[0057] In Fig. 10, the symbols shown in each row indicate a combination of a pair of soot blowers 70 that are simultaneously put into operation by the control unit 50. For example, 70F1a, 70B6a indicate that the soot blower 70F1a attached to the front wall 101a and the soot blower 70B6a attached to the rear wall 101b are simultaneously put into operation. Note that, although the example shown in Fig. 10 shows that the soot blower 70 attached to the front wall 101a and the soot blower 70 attached to the rear wall 101b are simultaneously put into operation, other embodiments may be used. For example, the soot blower 70 attached to the front wall 101a and the soot blower 70 attached to the rear wall 101b may be put into operation at different times.

[0058] In Fig. 10, the symbols in each column indicate the value of the differential temperature value Tdif calculated from the temperature values ​​T1, T2 detected by the temperature detection sensors 60 when a pair of soot blowers 70 in each row is operated. In Fig. 10, A, B, C, and D respectively indicate the range of the differential temperature value Tdif, with the relationship A>B>C>D. For example, when soot blowers 70F1a and 70B6a are operated simultaneously, the temperature detection sensor 60n has the largest differential temperature value Tdif.

[0059] The control unit 50 stores in a memory unit (not shown) a table indicating which range, A, B, C, or D, the multiple temperature detection sensors 60 and the differential temperature value Tdif shown in Fig. 10 fall into. Then, as described below, the control unit 50 reads out the table stored in the memory unit and, when operating a pair of soot blowers 70, identifies the maximum value among the multiple differential temperature values ​​Tdif corresponding to the multiple temperature detection sensors 60, and controls the operation of the pair of soot blowers 70 based on the maximum value.

[0060] 10, the range of the differential temperature value Tdif is divided into four stages, A, B, C, and D, but other embodiments are also possible. For example, it may be divided into a number of stages more than four stages, or the differential temperature value Tdif may be used as a value in a table as it is without being divided into the stages A, B, C, and D. Also, for example, instead of dividing it into the four stages A, B, C, and D shown in FIG. 10, it may be displayed on a display unit (not shown) as a four-stage grayscale image.

[0061] Fig. 11 is a diagram showing, in a shading image, the differential temperature value Tdif between the maximum temperature value T1 and the minimum temperature value T2 detected by the multiple temperature detection sensors 60 when the soot blower 70 is operated. The image shown in four types of shading in Fig. 11 corresponds to the four ranges of the differential temperature value Tdif, A, B, C, and D, shown in Fig. 10. The boiler 10 of this embodiment includes a display unit that displays multiple differential temperature values ​​(temperature differences) Tdif in association with the temperature detection sensors 60 corresponding to each differential temperature value Tdif when a specific soot blower 70 performs steam injection.

[0062] A (the range with the largest differential temperature value Tdif) shown in Fig. 10 corresponds to the highest density image area in Fig. 11, and B (the range with the second largest differential temperature value Tdif after A) corresponds to the second highest density image area in Fig. 11. D (the range with the smallest differential temperature value Tdif) shown in Fig. 10 corresponds to the lowest density image area in Fig. 11, and C (the range with the second smallest differential temperature value Tdif after D) corresponds to the second lowest density image area in Fig. 11.

[0063] 11 on the display unit, an operator of the boiler system 100 can intuitively recognize at which position in the furnace 11 the differential temperature value Tdif becomes large (i.e., the amount of clinker removed becomes large) when steam injection is performed by a specified soot blower 70. For example, the operator can identify from the grayscale image the soot blower 70 that was operated when the differential temperature value Tdif became large (i.e., the amount of clinker removed becomes large), and set the control unit 50 so that the operation interval at which the identified soot blower 70 performs steam injection is shortened.

[0064] Next, an operation for setting a predetermined operation interval of the soot blower 70 will be described with reference to Fig. 12. Fig. 12 is a flowchart showing an operation for setting a predetermined operation interval of the soot blower 70. Each process shown in Fig. 12 is executed by the control unit 50.

[0065] In step S101, the control unit 50 controls a predetermined soot blower 70 to start its operation.

[0066] In step S102, the control unit 50 detects the maximum temperature value (first temperature detection value) T1 detected by the multiple temperature detection sensors 60 during a first period PR1 from time t2 during steam injection from the spray holes 71a, 71b to time t3 when the soot blower 70 is stopped. The control unit 50 also detects the minimum temperature value (second temperature detection value) T2 detected by the multiple temperature detection sensors 60 during a second period PR2 from time t1 when the soot blower 70 is started to time t2 during steam injection from the spray holes 71a, 71b.

[0067] In step S103, the control unit 50 calculates differential temperature values ​​Tdif, which are obtained by subtracting temperature value T2 from temperature value T1, based on temperature values ​​T1 and T2 detected by the multiple temperature detection sensors 60, in association with the multiple temperature detection sensors 60. Then, the control unit 50 calculates the maximum value of the multiple differential temperature values ​​Tdif.

[0068] In step S104, the control unit 50 sets a predetermined operation interval of the soot blower 70 based on the maximum value calculated in step S103. The control unit 50 sets the operation interval so that the operation interval becomes shorter as the maximum value increases.

[0069] In step S105, the control unit 50 controls the operation of a specific soot blower 70 to stop, and ends the processing of this flowchart. The control unit 50 executes a series of processes of the flowchart shown in Figure 12 for each of the multiple soot blowers 70, and sets an operation interval for each of the multiple soot blowers 70.

[0070] 12, in step S102, the temperature values ​​T1 and T2 are detected, and in step S103, the differential temperature value Tdif is calculated in association with the multiple temperature detection sensors 60, but other aspects are also possible. For example, in step S102, only the temperature value T1 may be detected, and in step S103, the maximum value of the multiple temperature values ​​T1 may be calculated. In this case, in step S104, the control unit 50 sets an operation interval at which a predetermined soot blower 70 performs steam injection based on the maximum value of the multiple temperature values ​​T1.

[0071] In this case, it is preferable that the boiler 10 is provided with a display unit that displays multiple temperature values ​​T1 in correspondence with the temperature detection sensor 60 corresponding to each temperature value T1 when a specified soot blower 70 performs steam injection.

[0072] Next, a process for operating a predetermined soot blower 70 at a set operation interval will be described with reference to Fig. 13. Fig. 13 is a flow chart showing a process for operating a predetermined soot blower 70 at a set operation interval.

[0073] In step S201, the control unit 50 controls a predetermined soot blower 70 to start its operation. In step S202, the control unit 50 controls a predetermined soot blower 70 to stop its operation.

[0074] In step S203, the control unit 50 determines whether to stop the boiler 10, and if YES, ends the processing of this flowchart and executes an operation to stop the boiler 10. If NO, the control unit 50 advances the processing to step S204.

[0075] In step S204, the control unit 50 determines whether the predetermined operation interval of the soot blower 70 set in step S104 of Fig. 12 has elapsed, and if YES, the process proceeds to step S201 to again perform the predetermined operation of the soot blower 70. If NO, the process of step S204 is repeated.

[0076] According to the boiler system 100 of the present embodiment described above, the following actions and effects are achieved. According to the boiler system 100 of this embodiment, the control unit 50 controls the operation of the specified soot blower 70 based on multiple temperature values ​​T1 detected by multiple temperature detection sensors 60 during the first period PR1 from the start of the specified soot blower 70 to the start of steam injection. Since the first period PR1 is a period during which the specified soot blower 70 starts steam injection in an inserted state, the temperature of the heat transfer tube 101C after the clinker has been removed by steam injection can be detected. The higher the temperature of the heat transfer tube 101C after the clinker has been removed, the greater the amount of clinker removed. Therefore, by controlling the operation of the specified soot blower 70 based on multiple temperature values ​​T1, the soot blower 70 can be operated appropriately according to the state of the furnace, such as the amount of clinker attached.

[0077] Furthermore, according to the boiler system 100 of this embodiment, by detecting a plurality of temperature values ​​T2 detected by the plurality of temperature detection sensors 60 in the second period PR2 prior to the first period PR1, a plurality of differential temperature values ​​Tdif, which are the differences between the plurality of temperature values ​​T1 and the plurality of temperature values ​​T2, can be calculated. Since the differential temperature value Tdif corresponds to the amount of clinker removed, the soot blower 70 can be appropriately operated according to the state of the furnace, such as the amount of attached clinker.

[0078] Furthermore, according to the boiler system 100 of this embodiment, multiple differential temperature values ​​Tdif are displayed in correspondence with the temperature detection sensors 60 corresponding to each differential temperature value Tdif, so that the operator of the boiler system 100 can intuitively recognize at which position in the furnace 11 the temperature difference is large (i.e., the amount of clinker removed is large).

[0079] Furthermore, according to the boiler system 100 of this embodiment, the first period PR1 is a period during which a certain soot blower 70 starts injecting steam while inserted, so the multiple temperature values ​​T1 correspond to the amount of clinker removed. Therefore, the soot blower 70 can be operated appropriately according to the state of the furnace 11, such as the amount of clinker adhesion.

[0080] According to the boiler system 100 of this embodiment, multiple temperature values ​​T1 are displayed in correspondence with the temperature detection sensors 60 corresponding to each temperature value T1, so that the operator of the boiler system 100 can intuitively recognize at which position in the furnace 11 the temperature difference is large (i.e., the amount of clinker removed is large).

[0081] Other Embodiments In the above description, the boiler system 100 has multiple temperature detection sensors 60 that detect the temperatures of multiple heat transfer tubes 101C, and the control unit 50 controls the operation of a specific soot blower 70 based on multiple temperature values ​​(first temperature detection values) detected by the multiple temperature detection sensors 60 during the first period PR1 in which a specific soot blower 70 starts steam injection injecting steam in an inserted state, but other embodiments may also be used.

[0082] For example, the boiler system 100 may have a plurality of temperature detection sensors that detect the temperature of the combustion gas flowing through the combustion gas passage 12, and the control unit 50 may be configured to control the operation of a specified soot blower based on a plurality of temperature values ​​(first temperature detection values) detected by the plurality of temperature detection sensors during a first period PR1 in which a specified soot blower is inserted and starts steam injection.

[0083] In this case, the multiple soot blowers inject steam into heat exchangers (superheater 102, reheater 103, economizer 104) arranged in the combustion gas passage 12, and are switchable between an inserted state in which they are inserted into the combustion gas passage 12 and a withdrawn state in which they are withdrawn from the combustion gas passage 12.

[0084] When a predetermined soot blower is operated to perform steam injection to inject steam onto the surface of the heat exchanger, the control unit 50 calculates a differential temperature value Tdif from the combustion gas temperature values ​​T1, T2 detected by the multiple temperature detection sensors, and controls the operation of the predetermined soot blower according to the differential temperature value Tdif. For example, by shortening the operation interval at which the predetermined soot blower performs steam injection as the differential temperature value Tdif increases, the soot blower 70 can be appropriately operated according to the state of the combustion gas passage 12 so as to remove clinker from areas where a large amount of clinker has accumulated.

[0085] The boiler system and the boiler control method described in each of the above-described embodiments can be understood, for example, as follows.

[0086] A boiler system according to a first aspect of the present disclosure includes a boiler (10) and a control unit (50) that controls the boiler. The boiler has a furnace (11) composed of a furnace wall (101) having a plurality of heat transfer tubes through which a fluid flows, a combustion device (20) that injects solid fuel and combustion air into the furnace to generate combustion gas, a plurality of soot blowers (70) that inject steam onto the surface of the heat transfer tubes and are switchable between an inserted state in which the soot blowers are inserted into the furnace and an extracted state in which the soot blowers are extracted from the furnace, and a plurality of temperature detection units (60) that detect the temperatures of the plurality of heat transfer tubes. The control unit controls the operation of a predetermined soot blower based on a plurality of first temperature detection values ​​detected by the plurality of temperature detection units during a first period (PR1) in which a predetermined soot blower starts steam injection to inject steam in the inserted state.

[0087] According to the boiler system according to the first aspect of the present disclosure, the control unit controls the operation of the specified soot blower based on a plurality of first temperature detection values ​​detected by a plurality of temperature detection units during a first period (PR1) during which the specified soot blower starts steam injection in an inserted state. Since the first period is a period during which the specified soot blower starts steam injection in an inserted state, the temperature of the heat transfer tube after the clinker has been removed by steam injection can be detected. The higher the temperature of the heat transfer tube after the clinker has been removed, the greater the amount of clinker removed. Therefore, by controlling the operation of the specified soot blower based on a plurality of first temperature detection values, the soot blower can be operated appropriately according to the state of the furnace, such as the amount of clinker attached.

[0088] The boiler system according to the second aspect of the present disclosure is the first aspect, and further includes the following configuration: That is, the control unit controls an operation interval at which the predetermined soot blower performs the steam injection, based on a plurality of temperature differences that are differences between the plurality of temperature detection values ​​and a plurality of second temperature detection values ​​detected by the plurality of temperature detection units in a second period (PR2) prior to the first period (PR1). According to the boiler system of the second aspect of the present disclosure, by detecting the second temperature detection values ​​detected by the temperature detection units in a second period before the first period, it is possible to calculate the temperature differences between the first temperature detection values ​​and the second temperature detection values. Since the temperature differences correspond to the amount of clinker removed, the soot blower can be operated appropriately according to the state of the furnace, such as the amount of attached clinker.

[0089] The boiler system according to the third aspect of the present disclosure is the second aspect, further including the following configuration: the first temperature detection value is a maximum temperature value detected by the temperature detection unit in the first period, and the second temperature detection value is a minimum temperature value detected by the temperature detection unit in the second period. According to the boiler system of the third aspect of the present disclosure, the soot blower can be operated appropriately based on the difference between the maximum temperature value detected by the temperature detection unit in the first period and the minimum temperature value detected by the temperature detection unit in the second period.

[0090] The boiler system according to a fourth aspect of the present disclosure is the second or third aspect, further comprising the following configuration: A display unit that displays a plurality of the temperature differences in association with the temperature detection units corresponding to the respective temperature differences when the predetermined soot blower performs the steam injection. According to the boiler system of the fourth aspect of the present disclosure, multiple temperature differences are displayed in correspondence with the temperature detection units corresponding to each temperature difference, so that an operator of the boiler system can intuitively recognize at which position in the furnace the temperature difference is larger (i.e., where the amount of clinker removed is greater).

[0091] The boiler system according to the fifth aspect of the present disclosure is the first aspect, further comprising the following configuration: That is, the control unit controls an operation interval at which the predetermined soot blower performs the steam injection, based on a plurality of the first temperature detection values. According to the boiler system of the fifth aspect of the present disclosure, the first period is a period during which a certain soot blower starts to inject steam while inserted, so that the first temperature detection values ​​correspond to the amount of clinker removed, and therefore the soot blower can be operated appropriately according to the state of the furnace, such as the amount of adhering clinker.

[0092] A boiler system according to a sixth aspect of the present disclosure is the fifth aspect, further including the following configuration: That is, the first temperature detection value is a temperature value detected by the temperature detection unit in the first period. According to the boiler system according to the sixth aspect of the present disclosure, the soot blower can be appropriately operated based on the temperature value detected by the temperature detection unit in the first period.

[0093] The boiler system according to a seventh aspect of the present disclosure is the fifth or sixth aspect, further comprising the following configuration: A display unit that displays a plurality of the first temperature detection values ​​in association with the temperature detection units corresponding to the respective first temperature detection values ​​when the predetermined soot blower performs the steam injection. According to the boiler system of the seventh aspect of the present disclosure, multiple first temperature detection values ​​are displayed in correspondence with the temperature detection units corresponding to each first temperature detection value, so that an operator of the boiler system can intuitively recognize at which position in the furnace the temperature difference is larger (i.e., where the amount of clinker removed is greater).

[0094] In a boiler control method according to an eighth aspect of the present disclosure, the boiler has a furnace composed of a furnace wall having a plurality of heat transfer tubes through which a fluid flows, a combustion device that injects solid fuel and combustion air into the furnace to generate combustion gas, and a plurality of soot blowers that inject steam onto the surface of the heat transfer tubes and are switchable between an inserted state in which they are inserted into the furnace and an extracted state in which they are extracted from the furnace, and is provided with a temperature detection process (S102) for detecting the temperatures of the plurality of heat transfer tubes using a plurality of temperature detection units, and a control process (S104) for controlling the operation of a predetermined soot blower based on a plurality of first temperature detection values ​​detected by the plurality of temperature detection units during a first period in which a predetermined soot blower starts steam injection in the inserted state.

[0095] According to the boiler control method according to the eighth aspect of the present disclosure, the control step controls the operation of the predetermined soot blower based on a plurality of first temperature detection values ​​detected by a plurality of temperature detection units in a first period after the predetermined soot blower starts steam injection injecting steam in an inserted state. Since the first period is a period after the predetermined soot blower starts steam injection injecting steam in an inserted state, the temperature of the heat transfer tube after the clinker is removed by steam injection can be detected. The higher the temperature of the heat transfer tube after the clinker is removed, the greater the amount of clinker removed. Therefore, by controlling the operation of the predetermined soot blower based on a plurality of first temperature detection values, the soot blower can be operated appropriately according to the state of the furnace, such as the amount of clinker attached.

[0096] A boiler system according to a ninth aspect of the present disclosure comprises a boiler and a control unit that controls the boiler, the boiler having a furnace, a combustion device that injects solid fuel and combustion air into the furnace to generate combustion gas, a combustion gas passage through which the combustion gas generated by the combustion device flows, a heat exchanger arranged in the combustion gas passage and recovering heat from the combustion gas, a plurality of soot blowers that inject steam into the heat exchanger and are switchable between an inserted state inserted into the combustion gas passage and an extracted state extracted from the combustion gas passage, and a plurality of temperature detection units that detect the temperature of the combustion gas flowing through the combustion gas passage, and the control unit controls the operation of a predetermined soot blower based on a plurality of first temperature detection values ​​detected by the plurality of temperature detection units during a first period during which a predetermined soot blower starts steam injection in the inserted state.

[0097] According to the boiler system according to the ninth aspect of the present disclosure, the control unit controls the operation of the specified soot blower based on a plurality of first temperature detection values ​​detected by a plurality of temperature detection units during a first period during which the specified soot blower starts steam injection in an inserted state. Since the first period is a period during which the specified soot blower starts steam injection in an inserted state, the temperature of the heat transfer tube after the clinker is removed by steam injection can be detected. The lower the temperature of the combustion gas after the clinker is removed, the greater the amount of clinker removed. Therefore, by controlling the operation of the specified soot blower based on a plurality of first temperature detection values, the soot blower can be operated appropriately according to the state of the furnace, such as the amount of clinker adhesion. [Explanation of symbols]

[0098] 10. Boiler 11 Furnace 20 Combustion equipment 21 Burner 31 Mil 50 Control section 60 Temperature detection sensor 70 Soot Blower 71 Nozzle Block 71a,71b spray hole 72 Sootblower tube 73 Motor 74 Atomizing steam supply line 75 Steam pressure control valve 100 Boiler System 101 Furnace wall 101C Heat transfer tube VD Vertical direction PR1 1st period PR2 2nd period Tdif Temperature difference value Tmax, Tmin temperature values

Claims

1. Boiler and A control unit for controlling the boiler, The boiler comprises: A furnace having a furnace wall with a plurality of heat transfer tubes through which a fluid flows; a combustion device that injects solid fuel and combustion air into the furnace to generate combustion gas; A plurality of soot blowers that inject steam onto a surface of the heat transfer tube and are switchable between an inserted state in which the soot blowers are inserted into the furnace and a withdrawn state in which the soot blowers are withdrawn from the furnace; A plurality of temperature detection units for detecting the temperatures of the plurality of heat transfer tubes, The control unit controls the operation of the specified soot blower based on a plurality of first temperature detection values ​​detected by a plurality of temperature detection units during a first period in which the specified soot blower starts steam injection in the inserted state.

2. The boiler system of claim 1, wherein the control unit controls the operating interval at which the specified soot blower performs the steam injection based on a plurality of temperature differences which are the differences between a plurality of the first temperature detection values ​​and a plurality of second temperature detection values ​​detected by a plurality of the temperature detection units in a second period prior to the first period.

3. the first temperature detection value is a maximum temperature value detected by the temperature detection unit during the first period, The boiler system according to claim 2 , wherein the second detected temperature value is a minimum temperature value detected by the temperature detection unit during the second period.

4. A boiler system as described in claim 2 or claim 3, further comprising a display unit that displays a plurality of the temperature differences in correspondence with the temperature detection unit corresponding to each of the temperature differences when the specified soot blower performs the steam injection.

5. The boiler system according to claim 1 , wherein the control unit controls an operation interval at which the predetermined soot blower performs the steam injection based on a plurality of the first temperature detection values.

6. The boiler system according to claim 5 , wherein the first temperature detection value is a maximum temperature value detected by the temperature detection unit during the first period.

7. A boiler system as described in claim 5 or claim 6, further comprising a display unit that displays a plurality of the first temperature detection values ​​in correspondence with the temperature detection units corresponding to each of the first temperature detection values ​​when the specified soot blower performs the steam injection.

8. 1. A method for controlling a boiler, comprising: The boiler comprises: A furnace having a furnace wall with a plurality of heat transfer tubes through which a fluid flows; a combustion device that injects solid fuel and combustion air into the furnace to generate combustion gas; A plurality of soot blowers that inject steam onto the surface of the heat transfer tube and are switchable between an inserted state in which the soot blowers are inserted into the furnace and a withdrawn state in which the soot blowers are withdrawn from the furnace, a temperature detection step of detecting temperatures of the plurality of heat transfer tubes by a plurality of temperature detection units; A boiler control method comprising: a control process for controlling the operation of a specified soot blower based on a plurality of first temperature detection values ​​detected by a plurality of temperature detection units during a first period in which the specified soot blower starts steam injection in the inserted state.

9. Boiler and A control unit for controlling the boiler, The boiler comprises: The furnace and a combustion device that injects solid fuel and combustion air into the furnace to generate combustion gas; a combustion gas passage through which the combustion gas generated in the combustion device flows; a heat exchanger disposed in the combustion gas passage and configured to recover heat from the combustion gas; a plurality of soot blowers that inject steam into the heat exchanger and are switchable between an inserted state in which the soot blowers are inserted into the combustion gas passage and a withdrawn state in which the soot blowers are withdrawn from the combustion gas passage; a plurality of temperature detection units for detecting a temperature of the combustion gas flowing through the combustion gas passage; The control unit controls the operation of the specified soot blower based on a plurality of first temperature detection values ​​detected by a plurality of temperature detection units during a first period in which the specified soot blower starts steam injection in the inserted state.

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