Boiler system and boiler control method

Abstract

To appropriately control a boiler without requiring operation performed by an operator even when the properties of solid fuel which is supplied to a combustion apparatus change.SOLUTION: A boiler system is provided, including a boiler and a control unit controlling the boiler. The boiler includes: a furnace 11 composed of a furnace wall 101 having a heat transfer tube in which fluid flows; a combustion apparatus generating combustion gas by injecting solid fuel and combustion air to the furnace 11; a first temperature detection unit detecting first temperature of a lower region 101A of the furnace wall 101 to which the combustion apparatus is attached; and a second temperature detection unit detecting second temperature of an upper region 101B of the furnace wall 101 to which the combustion apparatus is not attached and which is disposed above the lower region 101A. The control unit controls the boiler on the basis of a temperature difference between the first temperature detected by the first temperature detection unit and the second temperature detected by the second temperature detection unit.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, coal-fired boilers that switch between different coal types with different properties are known (see, for example, Patent Document 1). Patent Document 1 discloses that in a coal-fired boiler that switches between different coal types with different properties, a change in the operating data of a coal mill is detected to determine the change in coal type for a coal bunker, and the setting of the boiler control mechanism is switched to the setting of the coal type after the change. Patent Document 1 also discloses that a change in combustion data such as the heat amount in the boiler, the temperature distribution in the boiler, and the boiler efficiency is detected to determine the change in coal type for the coal bunker that has the shortest remaining coal consumption time at that time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-315636 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, it is possible to detect changes in the operation data and combustion data of the coal mill to determine whether the coal type in the coal bunker has been switched, but it is not possible to directly set the boiler control mechanism based on the detection results of changes in the operation data and combustion data of the coal mill.The coal-fired boiler in Patent Document 1 is equipped with a storage means that stores property data such as calorific value and mass content by coal type, and allows the operator to change the property data of the coal type after switching by inputting the coal type number after switching in advance.

[0005] That is, in Patent Document 1, although the timing of the coal type change can be detected from changes in the operation data and combustion data of the coal mill, the coal type after the change and the settings of the boiler control mechanism for that coal type must be done in advance by the operator of the coal-fired boiler. Therefore, in Patent Document 1, the operator must recognize in advance what coal type the coal bunker's coal type will be changed to, and input the coal type number, etc. as settings of the boiler control mechanism.

[0006] 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 controlling the boiler in accordance with changes in the properties of solid fuel supplied to a combustion device without requiring operator operation when the properties of the solid fuel change. [Means for solving the problem]

[0007] A boiler system according to one embodiment of the present disclosure includes a boiler and a control unit that controls the boiler, the boiler having a furnace configured with a furnace wall having a heat transfer tube through which a fluid flows, a combustion device that injects solid fuel and combustion air into the furnace to generate combustion gas, a first temperature detection unit that detects a first temperature of a lower region of the furnace wall to which the combustion device is attached, and a second temperature detection unit that detects a second temperature of an upper region of the furnace wall to which the combustion device is not attached and which is located above the lower region, and the control unit controls the boiler based on a temperature difference between the first temperature detected by the first temperature detection unit and the second temperature detected by the second temperature detection unit.

[0008] In a boiler control method according to one embodiment of the present disclosure, the boiler includes a furnace configured with a furnace wall having a heat transfer tube through which a fluid flows, a combustion device that generates combustion gas by injecting solid fuel and combustion air into the furnace, a first temperature detection step of detecting a first temperature of a lower region of the furnace wall to which the combustion device is attached, a second temperature detection step of detecting a second temperature of an upper region of the furnace wall to which the combustion device is not attached and which is located above the lower region, and a control step of controlling the boiler based on a temperature difference between the first temperature detected by the first temperature detection unit and the second temperature detected by the second temperature detection unit. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a boiler system and a boiler control method that can appropriately control the boiler in accordance with changes in the properties of the solid fuel supplied to the combustion device without requiring operator operation, even when the properties of the solid fuel supplied to the combustion device change. [Brief description of the drawings]

[0010] [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. 3 is a cross-sectional view taken along the line DD in the upper region of the furnace wall shown in FIG. 2. [Diagram 5] 4 is a flowchart illustrating a method for controlling a boiler according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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").

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] Next, the first temperature detection unit 60 and the second temperature detection unit 70 for detecting the temperature of the furnace wall 101 will be described with reference to Figs. 2 to 4. Fig. 2 is a perspective view showing a furnace 11 according to one 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 line CC. Fig. 4 is a cross-sectional view of the upper region 101B of the furnace wall 101 shown in Fig. 2, taken along the line DD. Note that the furnace 11 and the furnace wall 101 shown in Figs. 2 to 4 are merely examples, and the shapes of the furnace 11 and the furnace wall 101 can be modified in various ways.

[0032] 2 to 4, 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 3, the boiler 10 of this embodiment has a first temperature detection unit 60 that detects a first temperature T1 in a lower region 101A in which the combustion device 20 is attached in the furnace wall 101. The first temperature detection unit 60 that detects a first temperature T1 [°C] in the lower region 101A is attached to the furnace wall 101 in which the burners 21A, 21B, 21C, 21D, 21E, and 21F of the combustion device 20 are attached.

[0037] 3, the first temperature detection unit 60 has a plurality of first temperature detection sensors 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 first temperature detection sensors 60a to 60t). The first temperature detection unit 60 detects, for example, an average value of temperatures output from the first temperature detection sensors 60a to 60t as a first temperature T1 [°C].

[0038] In addition, the first temperature detection unit 60 may detect the first temperature T1 using a predetermined calculation method based on the temperatures output from the first temperature detection sensors 60a to 60t, such as the highest temperature among the temperatures output from the first temperature detection sensors 60a to 60t, or the median of the standard deviation of the temperatures output from the first temperature detection sensors 60a to 60t.

[0039] 4, the boiler 10 of this embodiment has a second temperature detection unit 70 that detects a second temperature T2 in an upper region 101B of the furnace wall 101 where the combustion device 20 is not installed and which is located above the lower region 101A. A second temperature detection unit 70 that detects a second temperature T2 [°C] in the upper region 101B is installed in the furnace wall 101 where the burners 21A, 21B, 21C, 21D, 21E, and 21F of the combustion device 20 are not installed.

[0040] 3, the second temperature detection unit 70 has a plurality of second temperature detection sensors 70a, 70b, 70c, 70d, 70e, 70f, 70g, 70h, 70i, 70j, 70k, 70l, 70m, 70n, 70o, 70p, 70q, 70r, 70s, and 70t (hereinafter, also referred to as second temperature detection sensors 70a to 70t). The second temperature detection unit 70 detects, for example, an average value of temperatures output from the second temperature detection sensors 70a to 70t as a second temperature T2 [°C].

[0041] In addition, the second temperature detection unit 70 may detect the second temperature T2 using a predetermined calculation method based on the temperatures output from the second temperature detection sensors 70a-70t, such as the highest temperature among the temperatures output from the second temperature detection sensors 70a-70t, or the median of the standard deviation of the temperatures output from the second temperature detection sensors 70a-70t.

[0042] Next, a method for controlling the boiler 10 of this embodiment will be described with reference to Fig. 5. Fig. 5 is a flowchart showing a method for controlling the boiler 10 according to an embodiment of the present disclosure. The control unit 50 executes a control program to perform each process shown in Fig. 5. The process shown in Fig. 5 is a process executed by the control unit 50 while the boiler 10 is in operation.

[0043] In step S101, the control unit 50 acquires the first temperature T1 of the lower region 101A of the furnace wall 101 detected by the first temperature detection unit 60 from the first temperature detection unit 60. The first temperature detection unit 60 transmits the first temperature T1 of the lower region 101A of the furnace wall 101 to the control unit 50 in response to receiving a control command to detect the first temperature T1 from the control unit 50.

[0044] In step S102, the control unit 50 acquires the second temperature T2 of the upper region 101B of the furnace wall 101 detected by the second temperature detection unit 70 from the second temperature detection unit 70. In response to receiving a control command from the control unit 50 to detect the second temperature T2, the second temperature detection unit 70 transmits the second temperature T2 of the upper region 101B of the furnace wall 101 to the control unit 50.

[0045] In step S103, the control unit 50 determines whether the temperature difference obtained by subtracting the first temperature T1 from the second temperature T2 is higher than a predetermined temperature Ta, and if YES, proceeds to step S104, and if NO, proceeds to step S105.

[0046] In step S104, the control unit 50 estimates that the type of the solid fuel is low-fuel-ratio coal because the temperature difference obtained by subtracting the first temperature T1 from the second temperature T2 is higher than the predetermined temperature Ta.

[0047] In step S105, the control unit 50 determines whether the temperature difference obtained by subtracting the first temperature T1 from the second temperature T2 is lower than a predetermined temperature Tb, and if YES, proceeds to step S106, and if NO, proceeds to step S107.

[0048] In this embodiment, the temperature difference between the first temperature T1 and the second temperature T2 when multiple types of solid fuels are burned is acquired in advance, and the predetermined temperature Ta and the predetermined temperature Tb are set by associating the type of solid fuel with the temperature difference between the first temperature T1 and the second temperature T2 acquired in advance. For example, the temperature difference between the first temperature T1 and the second temperature T2 when three types of solid fuels, high fuel ratio, medium fuel ratio, and low fuel ratio, in descending order of fuel ratio of the solid fuel, are burned is acquired in advance.

[0049] Then, the numerical value between the temperature difference between the first temperature T1 and the second temperature T2 when the solid fuel with a high fuel ratio is burned and the temperature difference between the first temperature T1 and the second temperature T2 when the solid fuel with a medium fuel ratio is burned is set as the predetermined temperature Tb. Also, the numerical value between the temperature difference between the first temperature T1 and the second temperature T2 when the solid fuel with a medium fuel ratio is burned and the temperature difference between the first temperature T1 and the second temperature T2 when the solid fuel with a low fuel ratio is burned is set as the predetermined temperature Ta.

[0050] In step S106, the control unit 50 estimates that the type of the solid fuel is high-fuel-ratio coal because the temperature difference obtained by subtracting the first temperature T1 from the second temperature T2 is lower than the predetermined temperature Tb.

[0051] In step S107, the control unit 50 estimates that the type of solid fuel is medium fuel ratio coal because the temperature difference obtained by subtracting the first temperature T1 from the second temperature T2 is equal to or lower than the predetermined temperature Ta and equal to or higher than the predetermined temperature Tb.

[0052] In step S108, the control unit 50 estimates the fuel ratio of the solid fuel based on the temperature difference between the first temperature T1 detected by the first temperature detection unit 60 and the second temperature T2 detected by the second temperature detection unit 70, and sets control parameters for controlling the boiler 10 based on the fuel ratio. After setting the control parameters, the control unit 50 controls the boiler 10 based on the set control parameters.

[0053] Here, the control parameters of the boiler 10 are various parameters that affect the operating characteristics of the boiler 10, such as the flow rate setting of the superheater spray valve of the superheater 102. The control parameters of the boiler 10 are, for example, the spray flow rate for controlling the superheater spray valve to an appropriate temperature with respect to the main steam temperature. The control unit 50 estimates the fuel ratio of the solid fuel based on the temperature difference between the first temperature T1 detected by the first temperature detection unit 60 and the second temperature T2 detected by the second temperature detection unit 70, and controls the operation of the superheater spray valve based on the fuel ratio.

[0054] In addition to the flow rate setting of the superheater spray valve, the control parameters include parameters for stabilizing boiler operation according to the load (such as the set values ​​of the outlet and inlet temperatures of each heat transfer tube), and these control parameters are switched according to the type of solid fuel.

[0055] 5, the control unit 50 estimates the fuel ratio of the solid fuel based on the temperature difference between the first temperature T1 detected by the first temperature detection unit 60 and the second temperature T2 detected by the second temperature detection unit 70, and sets the control parameters for controlling the boiler 10 based on the fuel ratio, but other aspects may be used. For example, the control unit 50 may directly set the control parameters for controlling the boiler 10 based on the temperature difference between the first temperature T1 detected by the first temperature detection unit 60 and the second temperature T2 detected by the second temperature detection unit 70.

[0056] For example, when controlling the flow rate of the superheater spray valve of the superheater 102 as a control parameter, the main steam temperature is associated in advance with the temperature difference between the first temperature T1 and the second temperature T2, and the spray flow rate is determined from the temperature difference. In addition, for other control parameters (e.g., the outlet temperature and inlet temperature of each heat transfer tube, etc.), the set values ​​of the control parameters are associated in advance with the temperature difference between the first temperature T1 and the second temperature T2, and the set values ​​of the control parameters are determined from the temperature difference.

[0057] According to the boiler system 100 of the present embodiment described above, the following actions and effects are achieved. According to the boiler system of this embodiment, a first temperature of a lower region of the furnace wall where the combustion device is installed is detected by the first temperature detection unit, and a second temperature of an upper region of the furnace wall where the combustion device is not installed and is disposed above the lower region is detected by the second temperature detection unit. The inventors have found a new finding that the larger the temperature difference obtained by subtracting the first temperature from the second temperature, the lower the fuel ratio of the solid fuel, and the smaller the temperature difference obtained by subtracting the first temperature from the second temperature, the higher the fuel ratio of the solid fuel.

[0058] According to the boiler system 100 of this embodiment, the boiler 10 is controlled based on the temperature difference between the first temperature T1 detected by the first temperature detection unit 60 and the second temperature T2 detected by the second temperature detection unit 70. Since the temperature difference corresponds to the fuel ratio of the solid fuel, the boiler 10 can be appropriately controlled in response to changes in the properties of the solid fuel without requiring any operation from an operator.

[0059] Furthermore, according to the boiler system 100 of this embodiment, the fuel ratio of the solid fuel can be estimated based on the temperature difference between the first temperature T1 detected by the first temperature detection unit 60 and the second temperature T2 detected by the second temperature detection unit 70, and the boiler 10 can be appropriately controlled based on the fuel ratio.

[0060] Furthermore, according to the boiler system 100 of this embodiment, the boiler 10 can be appropriately controlled based on the fuel ratio estimated based on the temperature difference between the first temperature T1 detected by the first temperature detection unit 60 and the second temperature T2 detected by the second temperature detection unit 70.

[0061] Furthermore, according to the boiler system 100 of this embodiment, the boiler 10 can be appropriately controlled in response to changes in the properties of the solid fuel based on the temperature difference between the first temperature T1 in the lower region 101A of the furnace wall 101 and the second temperature T2 in the upper region 101B of the furnace wall 101, in which the heat transfer tube is formed to extend along the vertical direction VD.

[0062] Furthermore, according to the boiler system 100 of this embodiment, the boiler 10 can be appropriately controlled in response to changes in the properties of the solid fuel based on the temperature difference between the first temperature T1 in the lower region 101A of the furnace wall 101, in which the heat transfer tubes are formed along the vertical direction, and the second temperature T2 in the upper region 101B of the furnace wall 101, in which the heat transfer tubes are formed to extend along the vertical direction VD.

[0063] The boiler system and the boiler control method described in each of the above-described embodiments can be understood, for example, as follows.

[0064] 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 includes a furnace (11) configured with a furnace wall (101) having 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 first temperature detection unit (60) that detects a first temperature (T1) of a lower region (101A) of the furnace wall to which the combustion device is attached, and a second temperature detection unit (70) that detects a second temperature (T2) of an upper region (101B) of the furnace wall to which the combustion device is not attached and which is located above the lower region, and the control unit controls the boiler based on a temperature difference between the first temperature detected by the first temperature detection unit and the second temperature detected by the second temperature detection unit.

[0065] According to the boiler system according to the first aspect of the present disclosure, a first temperature of a lower region of the furnace wall where the combustion device is installed is detected by a first temperature detection unit, and a second temperature of an upper region of the furnace wall where the combustion device is not installed and is disposed above the lower region is detected by a second temperature detection unit. The inventors have found a new finding that the larger the temperature difference obtained by subtracting the first temperature from the second temperature, the lower the fuel ratio of the solid fuel, and the smaller the temperature difference obtained by subtracting the first temperature from the second temperature, the higher the fuel ratio of the solid fuel.

[0066] According to the boiler system according to the first aspect of the present disclosure, the boiler is controlled based on the temperature difference between the first temperature detected by the first temperature detector and the second temperature detected by the second temperature detector. Since the temperature difference corresponds to the fuel ratio of the solid fuel, the boiler can be appropriately controlled in response to changes in the properties of the solid fuel without requiring an operator's operation.

[0067] The boiler system according to a second aspect of the present disclosure is the first aspect, further comprising the following configuration: That is, the control unit estimates a fuel ratio of the solid fuel based on the temperature difference, and controls the boiler based on the fuel ratio. According to the boiler system of the second aspect of the present disclosure, the fuel ratio of the solid fuel can be estimated based on the temperature difference between the first temperature detected by the first temperature detection unit and the second temperature detected by the second temperature detection unit, and the boiler can be appropriately controlled based on the fuel ratio.

[0068] The boiler system according to the third aspect of the present disclosure further includes the following configuration in the second aspect: the boiler includes a superheater having a superheater spray valve, and the control unit controls the operation of the superheater spray valve based on the fuel ratio. According to the boiler system of the third aspect of the present disclosure, the operation of the superheater spray valve is controlled based on a fuel ratio estimated based on the temperature difference between the first temperature detected by the first temperature detection unit and the second temperature detected by the second temperature detection unit, thereby making it possible to appropriately control the boiler in accordance with changes in the properties of the solid fuel.

[0069] A boiler system according to a fourth aspect of the present disclosure is any one of the first to third aspects, further comprising the following configuration: In the lower region of the furnace wall, the heat transfer tube is formed in a spiral shape so as to extend in a direction inclined with respect to a vertical direction, and in the upper region of the furnace wall, the heat transfer tube is formed so as to extend along the vertical direction. According to the boiler system of the fourth aspect of the present disclosure, the boiler can be appropriately controlled in response to changes in the properties of the solid fuel based on the temperature difference between a first temperature in a lower region of the furnace wall, where the heat transfer tubes are formed in a spiral shape, and a second temperature in an upper region of the furnace wall, where the heat transfer tubes are formed to extend along the vertical direction.

[0070] A boiler system according to a fifth aspect of the present disclosure is any one of the first to third aspects, further comprising the following configuration: In the lower region of the furnace wall, the heat transfer tube is formed to extend along a vertical direction, and in the upper region of the furnace wall, the heat transfer tube is formed to extend along the vertical direction. According to the boiler system of the fifth aspect of the present disclosure, the boiler can be appropriately controlled in response to changes in the properties of the solid fuel based on the temperature difference between a first temperature in a lower region of the furnace wall in which the heat transfer tubes are formed to extend along a straight direction and a second temperature in an upper region of the furnace wall in which the heat transfer tubes are formed to extend along a vertical direction.

[0071] In a boiler control method according to a sixth aspect of the present disclosure, the boiler has a furnace constituted by a furnace wall having a heat transfer tube through which a fluid flows, and a combustion device that generates combustion gas by injecting solid fuel and combustion air into the furnace, and is provided with a first temperature detection step of detecting a first temperature of a lower region of the furnace wall to which the combustion device is attached, a second temperature detection step of detecting a second temperature of an upper region of the furnace wall to which the combustion device is not attached and which is located above the lower region, and a control step of controlling the boiler based on a temperature difference between the first temperature detected by the first temperature detection step and the second temperature detected by the second temperature detection step.

[0072] According to the boiler control method of the sixth aspect of the present disclosure, a first temperature of a lower region of the furnace wall where the combustion device is installed is detected in a first temperature detection step, and a second temperature of an upper region of the furnace wall where the combustion device is not installed and which is disposed above the lower region is detected in a second temperature detection step. The inventors have found a new finding that the larger the temperature difference obtained by subtracting the first temperature from the second temperature, the lower the fuel ratio of the solid fuel, and the smaller the temperature difference obtained by subtracting the first temperature from the second temperature, the higher the fuel ratio of the solid fuel.

[0073] According to the boiler control method of the sixth aspect of the present disclosure, the boiler is controlled based on the temperature difference between the first temperature detected in the first temperature detection step and the second temperature detected in the second temperature detection step. Since the temperature difference corresponds to the fuel ratio of the solid fuel, the boiler can be appropriately controlled in response to changes in the properties of the solid fuel without requiring an operation from an operator.

[0074] A boiler control method according to a seventh aspect of the present disclosure is the sixth aspect, further comprising the following configuration: That is, the control step estimates a fuel ratio of the solid fuel based on the temperature difference, and controls the boiler based on the fuel ratio. According to the boiler control method of the seventh aspect of the present disclosure, the fuel ratio of the solid fuel is estimated based on the temperature difference between the first temperature detected in the first temperature detection process and the second temperature detected in the second temperature detection process, and the boiler can be appropriately controlled based on the fuel ratio.

[0075] The boiler control method according to an eighth aspect of the present disclosure is the seventh aspect, further comprising the following configuration: the boiler includes a superheater having a superheater spray valve, and the control step controls the operation of the superheater spray valve based on the fuel ratio. According to the boiler control method of the eighth aspect of the present disclosure, the operation of the superheater spray valve is controlled based on a fuel ratio estimated based on the temperature difference between the first temperature detected by the first temperature detection process and the second temperature detected by the second temperature detection process, thereby making it possible to appropriately control the boiler in accordance with changes in the properties of the solid fuel.

[0076] A boiler control method according to a ninth aspect of the present disclosure is any one of the sixth to eighth aspects, further comprising the following configuration: In the lower region of the furnace wall, the heat transfer tube is formed in a spiral shape so as to extend in a direction inclined with respect to a vertical direction, and in the upper region of the furnace wall, the heat transfer tube is formed so as to extend along the vertical direction. According to the boiler control method of the ninth aspect of the present disclosure, the boiler can be appropriately controlled in response to changes in the properties of the solid fuel based on the temperature difference between a first temperature in a lower region of the furnace wall in which the heat transfer tubes are formed in a spiral shape and a second temperature in an upper region of the furnace wall in which the heat transfer tubes are formed to extend along the vertical direction.

[0077] A boiler control method according to a tenth aspect of the present disclosure is any one of the sixth to eighth aspects, further comprising the following configuration: In the lower region of the furnace wall, the heat transfer tube is formed to extend along a vertical direction, and in the upper region of the furnace wall, the heat transfer tube is formed to extend along the vertical direction. According to the boiler control method of the tenth aspect of the present disclosure, the boiler can be appropriately controlled in response to changes in the properties of the solid fuel based on the temperature difference between a first temperature in a lower region of the furnace wall in which the heat transfer tubes are formed to extend along the vertical direction and a second temperature in an upper region of the furnace wall in which the heat transfer tubes are formed to extend along the vertical direction. [Explanation of symbols]

[0078] 10. Boiler 11 Furnace 12 Combustion gas passage 13 Flue 20 Combustion equipment 21, 21A, 21B, 21C, 21D, 21E, 21F Burner 22,22A,22B,22C,22D,22E,22F Fine fuel supply pipe 23 Wind Box 24 Wind road 25 Additional Air Port 26 Additional Air Duct 31 Mil 32 Forced draft fan 41 Gas Duct 42 Air preheater 43 Denitration equipment 44 Equipment 46 Desulfurization equipment 47 Chimney 50 Control section 60 First temperature detection unit 60a~60t First temperature detection sensor 70 Second temperature detection unit 70a~70t Second temperature detection sensor 100 Boiler System 101 Furnace wall 101A Lower area 101B Upper area 101C Heat transfer tube 101a Front wall 101b Back wall 101c Right side wall 101d Left side wall 102,102A,102B,102C Superheater 103,103A,103B Reheater 104 Economizer VD Vertical direction

Claims

1. Boiler and A control unit for controlling the boiler, The boiler comprises: A furnace configured with a furnace wall having a heat transfer tube through which a fluid flows; a combustion device that injects solid fuel and combustion air into the furnace to generate combustion gas; A first temperature detection unit that detects a first temperature of a lower region of the furnace wall where the combustion device is installed; A second temperature detection unit detects a second temperature of an upper region of the furnace wall to which the combustion device is not attached and which is disposed above the lower region, The control unit controls the boiler based on a temperature difference between the first temperature detected by the first temperature detection unit and the second temperature detected by the second temperature detection unit.

2. The boiler system according to claim 1 , wherein the control unit estimates a fuel ratio of the solid fuel based on the temperature difference, and controls the boiler based on the fuel ratio.

3. The boiler comprises: a superheater having a superheater spray valve; The boiler system of claim 2 , wherein the control unit controls operation of the superheater spray valve based on the fuel ratio.

4. In the lower region of the furnace wall, the heat transfer tube is formed in a spiral shape so as to extend in a direction inclined with respect to a vertical direction, The boiler system according to any one of claims 1 to 3, wherein in the upper region of the furnace wall, the heat transfer tubes are formed to extend along the vertical direction.

5. In the lower region of the furnace wall, the heat transfer tube is formed to extend along a vertical direction, The boiler system according to any one of claims 1 to 3, wherein in the upper region of the furnace wall, the heat transfer tubes are formed to extend along the vertical direction.

6. 1. A method for controlling a boiler, comprising: The boiler comprises: A furnace configured with a furnace wall having a heat transfer tube through which a fluid flows; a combustion device that injects solid fuel and combustion air into the furnace to generate combustion gas; a first temperature detection step of detecting a first temperature of a lower region of the furnace wall where the combustion device is installed; a second temperature detection step of detecting a second temperature of an upper region of the furnace wall to which the combustion device is not attached and which is disposed above the lower region; a control step of controlling the boiler based on a temperature difference between the first temperature detected in the first temperature detection step and the second temperature detected in the second temperature detection step.

7. The boiler control method according to claim 6 , wherein the control step estimates a fuel ratio of the solid fuel based on the temperature difference, and controls the boiler based on the fuel ratio.

8. The boiler comprises: a superheater having a superheater spray valve; 8. The method of claim 7, wherein the control step controls operation of the superheater spray valve based on the fuel ratio.

9. In the lower region of the furnace wall, the heat transfer tube is formed in a spiral shape so as to extend in a direction inclined with respect to a vertical direction, The boiler control method according to any one of claims 6 to 8, wherein in the upper region of the furnace wall, the heat transfer tubes are formed to extend along the vertical direction.

10. In the lower region of the furnace wall, the heat transfer tube is formed to extend along a vertical direction. It has been The boiler control method according to any one of claims 6 to 8, wherein in the upper region of the furnace wall, the heat transfer tubes are formed to extend along the vertical direction.

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