OPERATIONAL CONDITION IMPROVEMENT SYSTEM, POWER PLANT, OPERATIONAL CONDITION IMPROVEMENT METHOD, AND OPERATIONAL CONDITION IMPROVEMENT PROGRAM

Abstract

To provide an operational state improvement system, a power generation plant, an operational state improvement method and an operational state improvement program, which can effectively improve an operational state of a boiler.SOLUTION: An operational state improvement system 200 includes an adjustment section in which settable ranges of predetermined operation parameters (mill outlet temperature, conveyance gas flow rate, boiler outlet oxygen concentration and auxiliary gas flow rate) are preset and that adjusts the operation parameters within the settable ranges on the basis of a predetermined evaluation index based on an operational state of a boiler 10.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to an operating state improvement system, a power generation plant, an operating state improvement method, and an operating state improvement program.

Background Art

[0002] Large boilers such as power generation boilers have a furnace that is vertically installed in a hollow shape, and a plurality of burners are arranged along the circumferential direction of the furnace on the furnace wall. Further, in a large boiler, a flue is connected above the furnace in the vertical direction, and a heat exchanger for generating steam is arranged in this flue. Then, a flame is formed by the burner injecting a mixture of fuel and air (oxidizing gas) into the furnace, combustion gas is generated, and the combustion gas flows into the flue. A heat exchanger is installed in the region where the combustion gas flows, and water or steam flowing in the heat transfer tubes constituting the heat exchanger is heated to generate superheated steam.

[0003] In order to optimize the operation of the boiler, Patent Document 1 discloses a method using AI.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Normally, the operating parameters in boiler control are adjusted using a standard type of fuel (design fuel) in a trial operation, and the values of the operating parameters based on the adjustment results are set. For this reason, it is desired to more effectively optimize the operating parameters of the boiler in accordance with the operating state that changes due to factors such as the properties of the fuel used and the cumulative operating time.

[0006] When using AI as in Patent Document 1, a model for predicting and reproducing the operating state of a boiler when input conditions (such as fuel used and operating parameters) are changed is required, so there are issues such as time and cost required for introduction.

[0007] The present disclosure has been made in view of such circumstances, and an object thereof is to provide an operating state improvement system and a power generation plant that can effectively improve the operating state of a boiler, an operating state improvement method, and an operating state improvement program.

Means for Solving the Problems

[0008] A first aspect of the present disclosure includes an adjustment unit that adjusts the operating parameter within a settable range based on a predetermined evaluation index based on the operating state of the boiler, where the settable range is preset for a predetermined operating parameter, the evaluation index is the amount of improvement in boiler efficiency, the operating parameter is the mill outlet temperature which is the temperature of the fluid discharged from the mill, The flow rate of the conveying gas supplied to the mill, which is the conveying gas flow rate, and the oxygen concentration of the combustion gas discharged from the boiler, which is the boiler outlet oxygen concentration, and a plurality of the mills are provided for the boiler when there is the said mill during stoppage and at least any one of the auxiliary gas flow rates which is the flow rate of the auxiliary gas supplied to the stopped mill and when the adjustment unit uses, as the said operation parameters, the mill outlet temperature, the conveying gas flow rate, the boiler outlet oxygen concentration, and the auxiliary gas flow rate, the adjustment unit adjusts each of the said operation parameters in the order of the boiler outlet oxygen concentration, the mill outlet temperature, the conveying gas flow rate, and the auxiliary gas flow rate is an operating state improvement system.

[0009] A second aspect of the present disclosure has a step of adjusting the operating parameter within a settable range based on a predetermined evaluation index based on the operating state of the boiler, where the settable range is preset for a predetermined operating parameter, the evaluation index is the amount of improvement in boiler efficiency, the operating parameter is the mill outlet temperature which is the temperature of the fluid discharged from the mill, The flow rate of the conveying gas supplied to the mill, which is the conveying gas flow rate, and the oxygen concentration of the combustion gas discharged from the boiler, which is the boiler outlet oxygen concentration, and a plurality of the mills are provided for the boiler when there is the said mill during stoppage and at least any one of the auxiliary gas flow rates which is the flow rate of the auxiliary gas supplied to the stopped mill and the said adjusting step is that when using, as the said operation parameters, the mill outlet temperature, the conveying gas flow rate, the boiler outlet oxygen concentration, and the auxiliary gas flow rate, each of the said operation parameters is adjusted in the order of the boiler outlet oxygen concentration, the mill outlet temperature, the conveying gas flow rate, and the auxiliary gas flow rate is an operating state improvement method.

[0010] A third aspect of the present disclosure is a process in which a computer is caused to execute a process of adjusting the operating parameter within a preset adjustable range based on a predetermined evaluation index based on the operating state of the boiler, the evaluation index being the amount of improvement in boiler efficiency, and the operating parameter being the mill outlet temperature, which is the temperature of the fluid discharged from the mill, The flow rate of the conveying gas supplied to the mill, which is the conveying gas flow rate, and the oxygen concentration of the combustion gas discharged from the boiler, which is the boiler outlet oxygen concentration, and a plurality of the mills are provided for the boiler when there is the said mill during stoppage at least any one of the auxiliary gas flow rates, which is the flow rate of the auxiliary gas supplied to the stopped mill and the said adjusting process is that when using, as the said operation parameters, the mill outlet temperature, the conveying gas flow rate, the boiler outlet oxygen concentration, and the auxiliary gas flow rate, each of the said operation parameters is adjusted in the order of the boiler outlet oxygen concentration, the mill outlet temperature, the conveying gas flow rate, and the auxiliary gas flow rate is an operation state improvement program.

Advantages of the Invention

[0011] According to the present disclosure, there is an effect that the operating state of the boiler can be effectively improved.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0013] 〔First Embodiment〕 Hereinafter, a first embodiment of an operation state improvement system, a power generation plant, an operation state improvement method, and an operation state improvement program according to the present disclosure will be described with reference to the drawings. Note that the present invention is not limited by this embodiment, and when there are a plurality of embodiments, those configured by combining each embodiment are also included. In the following description, "up" and "upper" indicate the upper side in the vertical direction, and "down" and "lower" indicate the lower side in the vertical direction, and the vertical direction is not strict and includes errors.

[0014] FIG. 1 is a schematic configuration diagram showing the coal-fired boiler of this embodiment.

[0015] The coal-fired boiler 10 of this embodiment is a coal-fired (pulverized coal-fired) boiler that can use pulverized coal obtained by pulverizing coal (carbon-containing solid fuel) as pulverized fuel, burn this pulverized fuel with a burner, and exchange heat generated by this combustion with feed water or steam to generate superheated steam.

[0016] In this embodiment, as shown in FIG. 1, the coal-fired boiler 10 has a furnace 11, a combustion device 12, and a combustion gas passage 13. The furnace 11 has a hollow rectangular tube shape and is installed along the vertical direction. The furnace wall 101 that constitutes the furnace 11 is composed of a plurality of heat transfer tubes and fins connecting these tubes, and exchanges heat with water or steam flowing inside the heat transfer tubes due to the combustion of pulverized fuel, suppressing the temperature rise of the furnace wall.

[0017] The combustion device 12 is provided on the lower side of the furnace wall that constitutes the furnace 11. In this embodiment, the combustion device 12 has a plurality of burners (for example, 21, 22, 23, 24, 25) attached to the furnace wall. For example, one set of burners 21, 22, 23, 24, 25 that are arranged at equal intervals along the circumferential direction of the furnace 11 is arranged in a plurality of stages (for example, 5 stages in FIG. 1) along the vertical direction. However, the shape of the furnace, the number of burners in one stage, the number of stages, the arrangement, etc. are not limited to this embodiment.

[0018] The burners 21, 22, 23, 24, 25 are connected to a plurality of mills (pulverizers) 31, 32, 33, 34, 35 via pulverized coal supply pipes 26, 27, 28, 29, 30. For example, in these mills 31, 32, 33, 34, 35, a pulverizing table (not shown) is supported rotatably in the housing of the mill, and a plurality of pulverizing rollers (not shown) are supported rotatably in conjunction with the rotation of the pulverizing table above the pulverizing table. When coal is fed between the plurality of pulverizing rollers and the pulverizing table, it is pulverized and conveyed to a classifier (not shown) in the housing of the mill by the conveying gas (primary air, oxidizing gas) supplied from a primary air fan (PAF: Primary Air Fan) 38B, and the pulverized fuel classified within a predetermined particle size range can be supplied from the pulverized coal supply pipes 26, 27, 28, 29, 30 to the burners 21, 22, 23, 24, 25.

[0019] Further, a bellows 36 is provided at the mounting positions of burners 21, 22, 23, 24, 25 in the furnace 11, and one end of an air duct (air passage) 37 is connected to this bellows 36. The other end of the air duct 37 is provided with a forced draft fan (FDF) 38A.

[0020] As shown in FIG. 1, the combustion gas passage 13 is connected to the upper part of the furnace 11 in the vertical direction. The combustion gas passage 13 is provided with superheaters 102, 103, 104, reheaters 105, 106, and a fuel economizer 107 as heat exchangers for recovering the heat of the combustion gas, and heat exchange is performed between the combustion gas generated in the furnace 11 and the feed water and steam flowing inside each heat exchanger.

[0021] As shown in FIG. 1, a flue 14 through which the combustion gas that has undergone heat exchange on the downstream side thereof is discharged is connected to the combustion gas passage 13. An air heater (air preheater) 42 is provided between the flue 14 and the air duct 37, and heat exchange is performed between the air flowing through the air duct 37 and the combustion gas flowing through the flue 14, so that the combustion air supplied to the burners 21, 22, 23, 24, 25 can be heated up.

[0022] Further, a denitration device 43 is provided at a position upstream of the air heater 42 in the flue 14. The denitration device 43 supplies a reducing agent having an action of reducing nitrogen oxides such as ammonia and aqueous urea into the flue 14, and promotes the reaction between the nitrogen oxides in the combustion gas supplied with the reducing agent and the reducing agent by the catalytic action of a denitration catalyst installed in the denitration device 43, thereby removing and reducing the nitrogen oxides in the combustion gas. A gas duct 41 connected to the flue 14 is provided with a dust collecting device 44 such as an electrostatic precipitator, an induced draft fan (IDF) 45, a desulfurization device 46, etc. at a position downstream of the air heater 42, and a chimney 50 is provided at the downstream end.

[0023] On one hand, when a plurality of mills 31, 32, 33, 34, 35 are driven, the generated pulverized fuel is supplied to burners 21, 22, 23, 24, 25 through pulverized coal supply pipes 26, 27, 28, 29, 30 together with the conveying gas (primary air, oxidizing gas). Further, by performing heat exchange with the exhaust gas discharged from the flue 14 using the air heater 42, the heated combustion air (secondary air, oxidizing gas) is supplied to the burners 21, 22, 23, 24, 25 from the air duct 37 via the wind box 36. The burners 21, 22, 23, 24, 25 blow the pulverized fuel mixture in which the pulverized fuel and the conveying gas are mixed into the furnace 11 and blow the combustion air into the furnace 11. At this time, when the pulverized fuel mixture ignites, a flame can be formed. A flame is generated at the lower part inside the furnace 11, and the high-temperature combustion gas rises inside this furnace 11 and is discharged into the combustion gas passage 13. In this embodiment, air is used as the oxidizing gas. It may be one with a higher oxygen ratio than air or conversely one with a lower oxygen ratio, and it can be made usable by optimizing it with the fuel flow rate.

[0024] Further, an additional air port 39 is provided above the mounting positions of the burners 21, 22, 23, 24, 25 in the furnace 11. The end of an additional air duct 40 branched from the air duct 37 is connected to the additional air port 39. Therefore, the combustion air (secondary air, oxidizing gas) sent by the forced draft fan 38A can be supplied from the air duct 37 to the wind box 36 and supplied from this wind box 36 to each of the burners 21, 22, 23, 24, 25, and the additional combustion air (additional air) sent by the forced draft fan 38A can be supplied from the additional air duct 40 to the additional air port 39.

[0025] In the lower region CA1 of the furnace 11, the pulverized fuel mixture and combustion air (secondary air, oxidizing gas) burn to generate a flame. Here, the furnace 11 is set such that the air supply amount is less than the theoretical air amount with respect to the pulverized coal supply amount, so that the inside is maintained in a reducing atmosphere. That is, nitrogen oxides (NOx) generated by the combustion of pulverized coal are reduced in the region CA2 of the furnace 11, and then additional combustion air (additional air) is additionally supplied from the additional air port 39, whereby the oxidative combustion of pulverized coal is completed, and the generation amount of NOx due to the combustion of pulverized coal is reduced.

[0026] Thereafter, as shown in FIG. 1, the combustion gas exchanges heat with the second superheater 103, the third superheater 104, the first superheater 102 (hereinafter may be simply referred to as a superheater), the second reheater 106, the first reheater 105 (hereinafter may be simply referred to as a reheater), and the economizer 107 disposed in the combustion gas passage 13, then nitrogen oxides are reduced and removed by the denitration device 43, particulate matter is removed by the dust collector 44, sulfur oxides are removed by the desulfurization device 46, and then it is discharged into the atmosphere from the chimney 50. Note that the heat exchangers do not necessarily have to be arranged in the above-described order with respect to the combustion gas flow.

[0027] Next, as heat exchangers, the superheaters 102, 103, 104, the reheaters 105, 106, and the economizer 107 provided in the combustion gas passage 13 will be described in detail. FIG. 2 is a schematic diagram showing the heat exchangers provided in the coal-fired boiler 10. Note that in FIG. 1, the positions of the heat exchangers (superheaters 102, 103, 104, reheaters 105, 106, and economizer 107) in the combustion gas passage 13 are not accurately shown, and the arrangement order of the heat exchangers with respect to the combustion gas flow is not limited to the description in FIG. 1.

[0028] As shown in FIG. 2, the boiler power generation plant 1 of the present embodiment includes heat exchangers (superheaters 102, 103, 104, reheaters 105, 106, economizer 107) provided in the coal-fired boiler 10, a steam turbine 110 that is rotationally driven by the steam generated by the coal-fired boiler 10, and a generator 115 that is connected to the steam turbine 110 and generates electricity by the rotation of the steam turbine 110.

[0029] The steam turbine 110 rotationally driven by the steam generated in the coal-fired boiler 10 is composed of, for example, a high-pressure turbine 111, an intermediate-pressure turbine 112, and a low-pressure turbine 113. The steam from the reheaters 105 and 106 described later flows into the intermediate-pressure turbine 112 and then into the low-pressure turbine 113. A condenser 114 is connected to the low-pressure turbine 113, and the steam that has rotationally driven the low-pressure turbine 113 is cooled by cooling water (for example, seawater) in this condenser 114 to become condensate. The condenser 114 is connected to the economizer 107 via a feed water line L1. For example, a condensate pump (CP) 121, a low-pressure feed water heater 122, a boiler feed water pump (BFP) 123, and a high-pressure feed water heater 124 are provided in the feed water line L1. A part of the steam driving each of the steam turbines 111, 112, and 113 is extracted to the high-pressure feed water heater 124 and the low-pressure feed water heater 122 as a heat source via an extraction line (not shown), and the feed water supplied to the economizer 107 is heated.

[0030] For example, the case where the coal-fired boiler 10 is a once-through boiler will be described. The economizer 107 is connected to each evaporation tube of the furnace wall 101. When the feed water heated in the economizer 107 passes through the evaporation tubes constituting the furnace wall 101, it is heated by receiving radiation from the flame in the furnace 11 and is led to the steam separator 126. The steam separated by the steam separator 126 is supplied to the superheaters 102, 103, 104, and the drain water separated by the steam separator 126 is led to the condenser 114 via the drain water line L2 through the steam separator drain tank 127.

[0031] Also, when starting the once-through boiler or during low-load operation, etc., when the feed water supplied from the economizer 107 passes through the evaporation tubes constituting the furnace wall 101, not all of it evaporates. As a result, there may be an operating state (wet operating state) where there is a water level in the steam separator 126. In this wet operating state, the drain water separated by the steam separator 126 may be circulated through the circulation line L6 using the boiler circulation pump (BCP) 128 and merged into the middle of the feed water line L1, and then circulated and supplied from the economizer 107 to the evaporation tubes constituting the furnace wall 101.

[0032] When the combustion gas flows through the combustion gas passage 13, this combustion gas is heat-recovered by the superheaters 102, 103, 104, the reheaters 105, 106, and the economizer 107. On the other hand, the feed water supplied from the boiler feed pump (BFP) 123 is preheated by the economizer 107 and then heated to become steam when passing through the evaporation tubes constituting the furnace wall 101, and is led to the steam separator 126. The steam separated by the steam separator 126 is introduced into the superheaters 102, 103, 104 and superheated by the combustion gas. The superheated steam generated by the superheaters 102, 103, 104 is supplied to the high-pressure turbine 111 via the steam line L3 to rotationally drive the high-pressure turbine 111. The steam discharged from the high-pressure turbine 111 is introduced into the reheaters 105, 106 via the line L4 and superheated again. The steam superheated again is supplied to the low-pressure turbine 113 via the steam line L5 through the intermediate-pressure turbine 112 to rotationally drive the intermediate-pressure turbine 112 and the low-pressure turbine 113. The rotating shafts of the steam turbines 111, 112, 113 rotationally drive the generator 115 to generate electricity. The steam discharged from the low-pressure turbine 113 is cooled by the condenser 114 to become condensate and is sent back to the economizer 107 again via the feed water line L1.

[0033] Further, in the combustion gas passage 13, a soot blower (dust removal device) (not shown) may be disposed in the gaps between the heat transfer tubes of each heat exchanger such as the superheaters 102, 103, 104, the reheaters 105, 106, and the carbon saver 107, or in the gaps between the heat exchangers. The soot blower is disposed to extend in a direction substantially perpendicular to the wall surface of the combustion gas passage 13. The soot blower is an injection device that injects steam (gas) in a direction perpendicular to the axial direction with the direction perpendicular to the wall surface of the combustion gas passage 13 as the axial direction, and the injection direction can also be varied. The steam injected from the soot blower toward the heat exchangers such as the superheaters 102, 103, 104, the reheaters 105, 106, and the carbon saver 107 removes the combustion ash adhering and depositing on the surfaces of the heat transfer tubes of the heat exchangers, and suppresses a decrease in the heat exchange efficiency in each heat transfer tube of the heat exchanger.

[0034] Next, a specific configuration example of the configuration (boiler system) around the coal-fired boiler 10 will be described with reference to FIG. 3. As shown in FIG. 3, the primary air is pressurized by the primary air blower 38B and branches into a cold air flow path and a hot air flow path via the PAF damper D1. In the hot air flow path, a part of the primary air is heated as hot air through the air heater 42, merges with the cold air via the hot air dampers W1, W2, W3, W4, W5, and is supplied as the primary air to the mills 31, 32, 33, 34, 35.

[0035] In the cold air flow path, a part of the primary air bypasses the air heater 42 as cold air, merges with the hot air via the cold air dampers R1, R2, R3, R4, R5, and is supplied as the primary air to the mills 31, 32, 33, 34, 35. The primary air supplied to the mills 31, 32, 33, 34, 35 is supplied as a conveying gas together with the pulverized fuel through the pulverized coal supply pipes 26, 27, 28, 29, 30 to the burners 21, 22, 23, 24, 25.

[0036] The temperature of the mixed fluid of the pulverized fuel and the primary air discharged from each mill is measured at T1 in FIG. 3. That is, the temperature at T1 is the mill outlet temperature, which is the temperature of the mixed fluid of the pulverized fuel and the primary air discharged from the mill. The mill outlet temperature is measured for each of the mills.

[0037] As shown in FIG. 3, the secondary air is pressurized by the forced draft fan 38A, the flow rate is adjusted by the damper (FDF damper) D2, and is heated by the air heater 42. The heated secondary air is supplied to the plenum chamber 36 and is supplied from the burners 21, 22, 23, 24, 25 into the furnace 11 of the boiler 10.

[0038] The differential pressure between the inlet of the secondary air to the plenum chamber 36 and the inside of the furnace 11 is defined as the plenum differential pressure and is measured at P1 in FIG. 3. The plenum chamber 36 is provided with a damper (not shown) for adjusting the flow rate of the secondary air supplied to the burners 21, 22, 23, 24, 25.

[0039] The exhaust gas, which is the combustion gas discharged from the boiler 10, exchanges heat with the secondary air in the air heater 42. The oxygen concentration of the exhaust gas discharged from the boiler 10 is measured at M1 in FIG. 3. That is, the oxygen concentration at M1 is the boiler outlet oxygen concentration, which is the oxygen concentration of the combustion gas (exhaust gas) discharged from the boiler 10. After heat exchange in the air heater 42, that is, the temperature of the exhaust gas after heat recovery in the boiler system (air heater outlet gas temperature) is measured at T2.

[0040] Also, the conveying gas flow rate, which is the flow rate of the primary air supplied to each of the mills 31, 32, 33, 34, 35, is measured at F3 in FIG. 3.

[0041] As shown in Fig. 3, in a configuration where a plurality of mills 31, 32, 33, 34, 35 are provided, when the power generation plant 1 is operated at a partial load (a load smaller than the rated load), some of the mills (for example, 32, 33, 34, 35) are in an operating state (the corresponding burners 22, 23, 24, 25 are ignited), and the other mills (for example, mill 31) are in a stopped state (the corresponding burner 21 is extinguished). For the stopped mill (for example, mill 31), cold air is supplied as auxiliary gas (auxiliary primary air) for preventing the reverse flow of combustion gas in the furnace 11 to the corresponding burner (for example, burner 21) and for cooling the burner 21. Note that hot air is not supplied to the stopped mill. Thus, the auxiliary gas flow rate, which is the flow rate of the auxiliary primary air supplied to the stopped mill, is also measured at F3 in Fig. 3.

[0042] Next, the control device 200 will be described. The control device 200 controls the power generation plant 1. In particular, the control device 200 according to the present embodiment performs control for improving the operating state of the boiler 10.

[0043] Fig. 4 is a diagram showing an example of the hardware configuration of the control device 200 according to the present embodiment. As shown in Fig. 4, the control device 200 is a computer system (computing system), and includes, for example, a CPU 1100, a ROM (Read Only Memory) 1200 for storing programs executed by the CPU 1100 and the like, a RAM (Random Access Memory) 1300 that functions as a work area during the execution of each program, a hard disk drive (HDD) 1400 as a mass storage device, and a communication unit 1500 for connecting to a network or the like. Note that a solid state drive (SSD) may be used as the mass storage device. These components are connected via a bus 1800.

[0044] Further, the control device 200 may include an input unit including a keyboard, a mouse, etc., and a display unit including a liquid crystal display device for displaying data.

[0045] Note that the storage medium for storing programs and the like executed by the CPU 1100 is not limited to the ROM 1200. For example, other auxiliary storage devices such as magnetic disks, magneto-optical disks, and semiconductor memories may be used.

[0046] A series of processing procedures for realizing various functions described later are recorded in the form of a program in a hard disk drive 1400 or the like. The CPU 1100 reads this program into the RAM 1300 or the like and executes information processing and arithmetic operations, thereby realizing various functions described later. Note that the program may be in a form pre-installed in the ROM 1200 or other storage media, in a form provided in a state stored in a computer-readable storage medium, or in a form distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0047] FIG. 5 is a functional block diagram showing the functions of the control device (operation state improvement system) 200. As shown in FIG. 5, the control device 200 includes an adjustment confirmation unit 201, an evaluation unit 202, and an adjustment unit 203. Note that the adjustment confirmation unit 201 and the evaluation unit 202 may be omitted.

[0048] The adjustment confirmation unit 201 determines whether the operation parameters can be adjusted. Specifically, as described later, since a settable range is set for the operation parameters, the difference between the current value of the operation parameters and the limit value of the settable range is confirmed. For example, when the target operation parameter is the mill outlet temperature, the current mill outlet temperature is compared with the upper limit value in the settable range to calculate the difference. Then, it is determined whether this difference is equal to or greater than a preset threshold value.

[0049] The threshold value is set as the maximum value of the difference assumed to be such that the value of the current operating parameter is sufficiently close to the limit value of the settable range, and no effect of improving the boiler efficiency can be expected even if adjusted to the limit value. That is, the threshold value is set so as to be able to determine that the value of the operating parameter is close to the limit value. It is preferable that the threshold value is set for each operating parameter respectively.

[0050] For example, before the adjustment by the adjustment unit 203 described later, the confirmation unit 201 confirms the operating parameter to be adjusted, and when the difference is equal to or greater than a preset threshold value, the adjustment process is actually performed. On the other hand, when the difference is less than the preset threshold value, the adjustment process for this operating parameter is not executed. That is, the adjustment unit 203 described later does not perform adjustment on an operating parameter for which the difference (adjustable amount) of the operating parameter in the settable range is smaller than the threshold value.

[0051] In this way, in the confirmation unit 201, by being able to confirm the necessity of adjusting the operating parameter, it is possible to suppress the execution of unnecessary adjustment processes. Note that, instead of executing the confirmation process in the confirmation unit 201, the adjustment process may be performed in the adjustment unit 203 described later.

[0052] The evaluation unit 202 calculates a predetermined evaluation index (evaluation criterion) calculated from the operating state value of the boiler 10. In the present embodiment, the evaluation index is the improvement amount of the boiler efficiency. That is, the evaluation unit 202 evaluates the improvement amount of the boiler efficiency using the operating state value of the boiler 10. Note that the evaluation index is not limited to the improvement amount of the boiler efficiency, and any index that changes with the change in the operating state (adjustment of the operating parameter) can be set.

[0053] In the evaluation unit 202, the improvement amount of the boiler efficiency is calculated based on the change in a predetermined operating state value before and after the adjustment of the operating parameter. That is, it is evaluated whether the boiler efficiency has been improved by the change in the operating state value changed by the adjustment of the operating parameter. Note that the operating state value used for the evaluation is preset as a parameter capable of calculating the improvement amount of the boiler efficiency.

[0054] In this embodiment, the operating state values are the oxygen concentration M1 at the boiler outlet and the gas temperature T2 at the air heater outlet. The oxygen concentration M1 at the boiler outlet is the oxygen concentration of the combustion gas discharged from the boiler 10. The gas temperature T2 at the air heater outlet is the temperature of the combustion gas discharged from the air heater 42 that performs heat exchange between the combustion gas discharged from the boiler 10 and the air supplied to the boiler 10, and indicates the temperature of the combustion gas after the heat recovery in the boiler system is completed.

[0055] Specifically, the evaluation unit 202 calculates the amount of improvement in boiler efficiency due to the change in the gas temperature T2 at the air heater outlet and the amount of improvement in boiler efficiency due to the change in the oxygen concentration M1 at the boiler outlet.

[0056] The amount of improvement in boiler efficiency due to the change in the gas temperature T2 at the air heater outlet is calculated by a function ηt2(ΔT2) with respect to the change amount ΔT2 of the gas temperature T2 at the air heater outlet. The change amount ΔT2 of the gas temperature at the air heater outlet is obtained by subtracting the gas temperature T2b at the air heater outlet before adjustment from the gas temperature T2a at the air heater outlet after adjustment (ΔT2 = T2a - T2b). The function ηt2 is a function defined in advance to calculate the amount of improvement in boiler efficiency from the change amount ΔT2 of the gas temperature T2 at the air heater outlet, and may be a theoretical formula (design formula) or an empirical formula obtained from past operation results.

[0057] The amount of improvement in boiler efficiency due to the change in the oxygen concentration M1 at the boiler outlet is calculated by a function ηm1(ΔC) with respect to the change amount ΔC of the oxygen concentration M1 at the boiler outlet. The change amount ΔC of the oxygen concentration M1 at the boiler outlet is obtained by subtracting the oxygen concentration C1b at the boiler outlet before adjustment from the oxygen concentration C2a at the boiler outlet after adjustment (ΔC = C2a - C1b). The function ηm1 is a function defined in advance to calculate the amount of improvement in boiler efficiency from the change amount ΔC of the oxygen concentration M1 at the boiler outlet, and may be a theoretical formula (design formula) or an empirical formula obtained from past operation results.

[0058] Then, in the evaluation unit 202, the total boiler efficiency improvement amount is calculated by adding the boiler efficiency improvement amount ηt2(ΔT) due to the change in the air heater outlet gas temperature T2 and the boiler efficiency improvement amount ηm1(ΔC) due to the change in the boiler outlet oxygen concentration M1. That is, the total boiler efficiency improvement amount is calculated as ηt2(ΔT)+ηm1(ΔC).

[0059] The evaluation process in the evaluation unit 202 is executed, for example, after the adjustment process for the operation parameters is executed in the adjustment unit 203 described later, in order to confirm the improvement result. Also, the evaluation process in the evaluation unit 202 may be performed before the execution of the adjustment process in the adjustment unit 203. In this case, for example, an estimated value of the boiler efficiency improvement amount is calculated based on the adjustable amount of the operation parameters. For example, as described above, when ηt2(ΔT)+ηm1(ΔC) is used to calculate the total boiler efficiency improvement amount, ΔT2 and ΔC are estimated from the current values and adjustable amounts of the respective operation parameters, and an estimated value of the boiler efficiency improvement amount is calculated based on this. And when the estimated boiler efficiency improvement amount is equal to or greater than a preset threshold value, an adjustment process may be performed on the operation parameter.

[0060] The adjustment unit 203 has a preset adjustable range for a predetermined operation parameter related to the evaluation index, and adjusts the operation parameter within the adjustable range based on the evaluation index.

[0061] The operation parameters are preset based on the degree of influence on the evaluation index. The degree of influence represents the magnitude of the change in the evaluation index with respect to the adjustment of the operation parameter. That is, by adjusting the operation parameter with a high degree of influence, it becomes possible to effectively adjust the evaluation index.

[0062] In this embodiment, the operating parameter is at least one of the mill outlet temperature, the conveying gas flow rate, the boiler outlet oxygen concentration, and the auxiliary gas flow rate. Note that if it is an operating parameter with a large influence on the evaluation index, it is not limited to the above and can be used. The mill outlet temperature is the temperature of the mixture of pulverized fuel and conveying gas discharged from the mill. The conveying gas flow rate is the flow rate of the conveying gas supplied to the mill. The boiler outlet oxygen concentration is the oxygen concentration of the combustion gas discharged from the boiler 10. The auxiliary gas flow rate is the flow rate of the auxiliary gas supplied to the stopped mill when a plurality of mills are provided for the boiler 10.

[0063] And when the adjustment unit 203 uses a plurality of operating parameters, it performs adjustment in order from the operating parameter with a large influence on the evaluation index. The influence on the evaluation index indicates the degree to which the evaluation index can be effectively improved when the operating parameter is adjusted.

[0064] In this embodiment, the adjustment order of the operating parameters is preset in consideration of the influence degree. Specifically, the adjustment unit 203 adjusts each operating parameter in the order of the boiler outlet oxygen concentration M1, the mill outlet temperature T1, the conveying gas flow rate F3h, and the auxiliary gas flow rate F3c. Note that the order may be changed from the above, and when there is an unused operating parameter, the unused operating parameter may be omitted from the above order.

[0065] The adjustment of each operating parameter will be described respectively. Note that in the adjustment of each of the following operating parameters, the devices to be operated (such as each damper) are not limited to the described means, and other means may be used as long as the adjustment purpose can be achieved.

[0066] First, the case of adjusting the mill outlet temperature will be described. The adjustment unit 203 increases the mill outlet temperature T1 in order to improve the boiler efficiency. Specifically, the mill outlet temperature is increased by operating the set value of the mill outlet temperature T1 to the upper limit value within the settable range.

[0067] The adjustable range of the mill outlet temperature T1 has an upper limit set based on the properties of the coal used. Note that it is also possible to set a lower limit for the adjustable range of the mill outlet temperature T1. The coal properties are, for example, the O / C value (molar ratio of oxygen to carbon).

[0068] In this way, by increasing the mill outlet temperature T1 up to the upper limit of the adjustable range, the boiler efficiency is improved.

[0069] Figure 6 is a diagram showing an example of the relationship between the mill outlet temperature and the boiler efficiency. In Figure 6, the relationship between the mill outlet temperature and the outlet gas temperature of the air heater 42, and the relationship between the mill outlet temperature and the boiler efficiency are shown. When the set value of the mill outlet temperature is increased, in order to increase the mill inlet temperature, the control device 220 performs control to increase the opening degrees of the hot air dampers W1, W2, W3, W4, W5 and decrease the opening degrees of the cold air dampers R1, R2, R3, R4, R5. By this operation, the flow rate of the primary air (hot air) passing through the air heater 42 increases (the flow rate ratio of the cold air bypassing the air heater 42 decreases), and the heat exchange amount between the primary air and the exhaust gas in the air heater 42 increases. As a result, the air heater outlet gas temperature decreases, the exhaust gas loss, which is the amount of heat carried out of the boiler system by the exhaust gas, decreases, and the boiler efficiency is improved.

[0070] Next, the case of adjusting the flow rate of the conveying gas (primary air) will be described. The adjustment unit 203 reduces the flow rate of the primary air in order to improve the boiler efficiency. Specifically, the hot air dampers W1, W2, W3, W4, W5 and the cold air dampers R1, R2, R3, R4, R5 are operated in the closing direction to the lower limit value within the settable range. When the flow rate of the primary air decreases, in order to ensure the total air flow rate set according to the fuel supply amount to the boiler 10, the control device 200 performs control to increase the secondary air flow rate by operating the FDF damper D2 in the opening direction. By this operation, the flow rate of the secondary air passing through the air heater 42 increases, and the heat exchange amount between the secondary air and the exhaust gas in the air heater 42 increases. As a result, the outlet gas temperature of the air heater 42 decreases, the exhaust gas loss, which is the amount of heat carried out of the boiler system by the exhaust gas, decreases, and the boiler efficiency is improved. Further, when the flow rate of the primary air decreases, in order to ensure the amount of heat supplied to the mill (in order to maintain the mill outlet temperature at the set value), an operation to increase the mill inlet temperature, specifically, to increase the opening degrees of the hot air dampers W1, W2, W3, W4, W5 and decrease the opening degrees of the cold air dampers R1, R2, R3, R4, R5 is performed by the control device 200. By this operation, the flow rate ratio of the primary air (hot air) passing through the air heater 42 increases (the flow rate ratio of the cold air, which is the primary air bypassing the air heater 42, decreases), and the heat exchange amount between the primary air (hot air) and the exhaust gas in the air heater 42 increases. As a result, the outlet gas temperature of the air heater 42 decreases, the exhaust gas loss, which is the amount of heat carried out of the boiler system by the exhaust gas, decreases, and the boiler efficiency is improved.

[0071] The settable range of the conveying gas flow rate is such that the lower limit value of the conveying gas flow rate is set according to at least one of the sedimentation flow rate of the solid-gas two-phase flow of the pulverized fuel and the conveying gas passing through the burners 21, 22, 23, 24, 25 and the pulverized coal supply pipes 26, 27, 28, 29, 30, and the dryness of the pulverized fuel in the mill. The dryness indicates that the mill outlet temperature can be ensured to be equal to or higher than the lower limit value (desired drying has been performed). Note that an upper limit value may be set for the settable range of the conveying gas flow rate.

[0072] By controlling in this way, the flow rate of the air (hot air which is a part of the primary air and the secondary air) passing through the air heater 42 increases, and the heat exchange amount between the primary air and the exhaust gas in the air heater 42 increases. As a result, the exhaust gas temperature at the outlet of the air heater 42 decreases, the exhaust gas loss which is the amount of heat carried out of the boiler system by the exhaust gas decreases, and the boiler efficiency is improved. For this reason, the boiler efficiency is improved by reducing the conveyance gas flow rate to the lower limit value within the settable range.

[0073] Note that it is preferable to confirm that the opening degrees of the cold air dampers R1, R2, R3, R4, and R5 are equal to or greater than the control lower limit value (for example, 5%), and when the opening degrees of the cold air dampers R1, R2, R3, R4, and R5 reach the control lower limit value before decreasing to the lower limit value of the flow rate, the control for reducing the conveyance gas flow rate is preferably terminated. The control lower limit value is the minimum damper opening degree necessary for stably controlling the conveyance gas temperature and flow rate.

[0074] FIG. 7 is a diagram showing an example of the relationship between the conveyance gas flow rate and the boiler efficiency. In FIG. 7, the relationship between the conveyance gas flow rate and the required mill inlet air temperature, the relationship between the conveyance gas flow rate and the outlet gas temperature of the air heater 42, and the relationship between the conveyance gas flow rate and the boiler efficiency are shown. As shown in the relationship between the conveyance gas flow rate and the required mill inlet air temperature, there is a point P1 where the cold air dampers R1, R2, R3, R4, and R5 reach the lower limit, and the conveyance gas flow rate can be decreased until this point is reached. In this way, when the conveyance gas flow rate decreases, the boiler efficiency is improved.

[0075] Next, the case of adjusting the boiler outlet oxygen concentration will be described. The adjustment unit 203 decreases the boiler outlet oxygen concentration in order to improve the boiler efficiency. Specifically, the boiler outlet oxygen concentration is decreased by operating in the direction of decreasing the amount of supplied air to the boiler 10 to the lower limit value within the settable range. The amount of supplied air to the boiler 10 is operated by, for example, operating the FDF damper D2.

[0076] The adjustable range of the oxygen concentration M1 at the boiler outlet is set with a lower limit value based on a specified value of the oxygen concentration M1 at the boiler outlet set in advance. Note that an upper limit value may also be set for the adjustable range of the oxygen concentration M1 at the boiler outlet. The specified value of the oxygen concentration M1 at the boiler outlet is set in advance so that, for example, the unburned content in the ash is equal to or less than a preset upper limit value.

[0077] By reducing the setting of the oxygen concentration M1 at the boiler outlet, the amount of air supplied to the boiler 10 decreases. As a result, the amount of exhaust gas discharged from the boiler decreases, and exhaust gas losses can be reduced. In this way, by reducing the oxygen concentration M1 at the boiler outlet to the lower limit value of the adjustable range, the boiler efficiency is improved.

[0078] Note that when the oxygen concentration M1 at the boiler outlet is reduced, effects such as an increase in the carbon monoxide concentration in the exhaust gas and a decrease in the windbox differential pressure P1 occur. The increase in the carbon monoxide concentration in the exhaust gas is caused by incomplete combustion of the fuel, and the boiler efficiency decreases. Also, a decrease in the windbox differential pressure P1 may cause combustion instability in the burner. For this reason, an upper limit value for the carbon monoxide concentration and a lower limit value for the windbox differential pressure P1 are set in advance. When the upper limit value for the carbon monoxide concentration or the lower limit value for the windbox differential pressure P1 is reached when the oxygen concentration M1 at the boiler outlet is reduced to the lower limit value, it is preferable to end the control for reducing the oxygen concentration M1 at the boiler outlet.

[0079] Figure 8 is a diagram showing an example of the relationship between the oxygen concentration at the boiler outlet and the boiler efficiency. In Figure 8, the relationships between the oxygen concentration at the boiler outlet (oxygen concentration at the economizer outlet) and the amount of exhaust gas, between the oxygen concentration at the boiler outlet and the carbon monoxide concentration in the exhaust gas, between the oxygen concentration at the boiler outlet and the unburned content in the ash, between the boiler efficiency and the amount of exhaust gas, between the boiler efficiency and the carbon monoxide concentration in the exhaust gas, and between the boiler efficiency and the unburned content are shown. As described above, when the oxygen concentration at the boiler outlet decreases, the boiler efficiency is improved.

[0080] Next, the case of adjusting the auxiliary gas flow rate will be described. The adjusting unit 203 reduces the auxiliary gas flow rate to improve the boiler efficiency. Specifically, when the mill is stopped (for example, mill 31), auxiliary gas is supplied. At this time, since the cold air damper (R1) is open and the hot air damper (W1) is closed, the auxiliary gas becomes the air from the cold air damper (R1). Therefore, the auxiliary gas flow rate is reduced by operating the cold air damper (R1) corresponding to the stopped mill in the closing direction to the lower limit value within the adjustable range.

[0081] When the auxiliary gas is supplied to the stopped mill (for example, mill 31), it is then supplied to the corresponding burner in the fire extinguished state (for example, burner 21). If the auxiliary gas is insufficient, the cooling of the burner becomes insufficient, and there is a possibility of burner burnout. Therefore, the lower limit value of the adjustable range of the auxiliary gas flow rate is set based on the upper limit operating temperature of the burner. It is also possible to set an upper limit value for the adjustable range of the auxiliary gas flow rate. The upper limit operating temperature of the burner depends on the burner specifications (for example, the materials and shapes used), and the flow rate of the auxiliary gas required for cooling the burner varies depending on the load of the boiler 10 (the heat load in the furnace 11). Therefore, it is preferable to set the lower limit value of the auxiliary gas flow rate according to the load of the boiler 10 by installing a thermocouple or the like (not shown in the figure) in the burner to monitor the metal temperature. When a thermocouple cannot be installed (when the temperature cannot be monitored), for example, the lower limit value of the auxiliary gas flow rate corresponding to the upper limit operating temperature of the burner may be set differently according to the load of the boiler 10 (the heat load of the furnace 11).

[0082] Thus, when the flow rate of the auxiliary gas branched from the primary air (cold air) bypassing the air heater 42 decreases, in order to ensure the total air flow rate set according to the fuel supply amount to the boiler 10, the control device 200 performs control to increase the secondary air flow rate by operating the FDF damper D2 in the opening direction. By this operation, the flow rate of the secondary air passing through the air heater 42 increases, and the heat exchange amount between the secondary air and the exhaust gas in the air heater 42 increases. As a result, the air heater outlet gas temperature decreases, the exhaust gas loss, which is the amount of heat carried out of the boiler system by the exhaust gas, decreases, and the boiler efficiency is improved.

[0083] FIG. 9 is a diagram showing an example of the relationship between the auxiliary gas flow rate and the boiler efficiency. In FIG. 9, it is a diagram showing the relationship between the auxiliary gas flow rate and the metal temperature of the fire extinguishing burner, the relationship between the auxiliary gas flow rate and the outlet gas temperature of the air heater 42, and the relationship between the auxiliary gas flow rate and the boiler efficiency. Thus, when the auxiliary gas flow rate decreases, the boiler efficiency is improved.

[0084] Next, an example of the operation parameter adjustment process by the above-described control device 200 will be described with reference to FIG. 10. FIG. 10 is a flowchart showing an example of the procedure of the operation parameter adjustment process according to the present embodiment. The flow shown in FIG. 10 is executed, for example, when an instruction to start adjustment control for improving the boiler efficiency is given.

[0085] In the present embodiment, since the priority order for executing the operation parameters is set, accordingly, the boiler outlet oxygen concentration is set as number A = 1, the mill outlet temperature is set as number A = 2, the conveying gas flow rate is set as number A = 3, and the auxiliary gas flow rate is set as number A = 4.

[0086] First, set the operation parameter to number A = 1 (S101).

[0087] Next, it is determined whether the set operation parameter can be adjusted (S102). Specifically, it is determined whether the difference between the current value of the operation parameter and the limit value of the adjustable range is equal to or greater than the threshold value.

[0088] If it is adjustable (YES determination in S102), an adjustment process is executed for the set operation parameter (S103).

[0089] If it is not adjustable (NO determination in S102), S105 is executed.

[0090] Next, after adjusting the operation parameter, the amount of improvement in boiler efficiency is evaluated (S104). The evaluated amount of improvement in boiler efficiency may be notified to, for example, the operator of the power generation plant 1.

[0091] Next, it is determined whether the number A of the operation parameter is the final number (4 in this embodiment) (S105).

[0092] If the number A of the operation parameter is not the final number (NO determination in S105), in S106, 1 is added to the number A (A = A + 1), and S102 is executed. As a result, the process is executed again for the operation parameter with the number A = 2 from S102.

[0093] If the number A of the operation parameter is the final number (YES determination in S105), the process is terminated.

[0094] Note that the above process may be repeatedly executed until the target improvement effect of the boiler efficiency is obtained.

[0095] By executing the process as in the above flow, adjustment processing is executed for each operation parameter according to the priority. That is, as shown in FIG. 11, first, the oxygen concentration at the boiler outlet is adjusted. Specifically, the oxygen concentration at the boiler outlet is decreased within the settable range. Then, next, the mill outlet temperature is adjusted. Specifically, the mill outlet temperature is increased within the settable range. Then, next, the conveying gas flow rate is adjusted. Specifically, the conveying gas flow rate is decreased within the settable range. Then, next, the auxiliary gas flow rate is adjusted. Specifically, the auxiliary gas flow rate is decreased within the settable range.

[0096] In this way, adjustment processing for each operation parameter is executed according to the priority, and the improvement of the boiler efficiency is performed.

[0097] As described above, according to the operation state improvement system, power generation plant, operation state improvement method, and operation state improvement program according to the present embodiment, within a settable range, the operation parameters are adjusted based on a predetermined evaluation index calculated from the operation state values of the boiler 10. Therefore, it becomes possible to adjust the operation parameters to improve the evaluation index and the like. And since it is an adjustment of the operation parameters within the settable range, it is possible to suppress the setting of the operation parameters for improving the evaluation index and the like to inappropriate values. By using the improvement amount of the boiler efficiency as the evaluation index, it becomes possible to adjust the operation parameters to improve the boiler efficiency.

[0098] Also, for example, compared with a method of optimizing operation parameters using AI, it can be expected to omit the reduction of introduction costs, verification of reproducibility by a model, and the like.

[0099] Also, based on the oxygen concentration of the combustion gas discharged from the boiler 10 and the temperature of the combustion gas discharged from the air preheater 42 that performs heat exchange between the combustion gas and the air supplied to the combustion gas and the boiler 10, the improvement amount of the boiler efficiency can be efficiently calculated.

[0100] Also, by setting the operation parameters based on the degree of influence on the evaluation index, it becomes possible to effectively perform the adjustment process of the operation parameters with respect to the evaluation index. By adjusting the operation parameters with a large degree of influence on the evaluation index in order, it is possible to preferentially adjust the operation parameters with a large degree of influence and efficiently perform the adjustment with respect to the evaluation index.

[0101] Further, by using any one of the mill outlet temperature, the conveying gas flow rate, the boiler outlet oxygen concentration, and the auxiliary gas flow rate as an operation parameter, it becomes possible to effectively adjust the evaluation index (boiler efficiency). By adjusting the operation parameters in the order of the boiler outlet oxygen concentration, the mill outlet temperature, the conveying gas flow rate, and the auxiliary gas flow rate, it is possible to preferentially adjust the operation parameters that have a greater influence on the evaluation index (boiler efficiency). Therefore, it becomes possible to effectively adjust the evaluation index (boiler efficiency). By increasing the mill outlet temperature when adjusting the mill outlet temperature, decreasing the conveying gas flow rate when adjusting the conveying gas flow rate, decreasing the boiler outlet oxygen concentration when adjusting the boiler outlet oxygen concentration, and decreasing the auxiliary gas flow rate when adjusting the auxiliary gas flow rate, it becomes possible to effectively adjust the evaluation index (boiler efficiency).

[0102] 〔Second Embodiment〕 Next, the operation state improvement system, the power generation plant, the operation state improvement method, and the operation state improvement program according to the second embodiment of the present disclosure will be described. In the above-described first embodiment, the case where adjustment processing is executed for each operation parameter by setting the priority order in advance has been described. In this embodiment, the case where the execution order is determined based on the state (current value) of each operation parameter when performing the processing will be described. Hereinafter, the operation state improvement system, the power generation plant, the operation state improvement method, and the operation state improvement program according to this embodiment will be mainly described with respect to the differences from the first embodiment.

[0103] FIG. 12 is a flowchart showing the operation parameter adjustment process in this embodiment. In this embodiment, the case where the mill outlet temperature, the conveying gas flow rate, the boiler outlet oxygen concentration, and the auxiliary gas flow rate are used as operation parameters will be described as an example.

[0104] In FIG. 12, the auxiliary symbols for each operation parameter are set as a for the mill outlet temperature, b for the conveying gas flow rate, c for the boiler outlet oxygen concentration, and d for the auxiliary gas flow rate.

[0105] First, calculate the adjustable amount (S201). The adjustable amount is the difference between the limit value within the settable range and the current value for each operation parameter. In S201, the adjustable amount (difference) is calculated for each operation parameter. Specifically, Sa is calculated as the adjustable amount for the mill outlet temperature, Sb is calculated as the adjustable amount for the conveying gas flow rate, Sc is calculated as the adjustable amount for the boiler outlet oxygen concentration, and Sd is calculated as the adjustable amount for the auxiliary gas flow rate.

[0106] Next, calculate the expected value of the improvement in boiler efficiency (expected improvement value) (S202). That is, the evaluation unit 202 performs an evaluation. The expected improvement value is the expected value (estimated value) of the amount by which the boiler efficiency is improved when the operation parameters are manipulated by only the adjustable amount. The expected improvement value is calculated using a predetermined function with the adjustable amount as a variable. The function is set in advance. Also, once the expected improvement value is calculated from the adjustable amount, it is not limited to the method of using a function. The function may be a theoretical formula (design formula) or an empirical formula based on past operation data.

[0107] Specifically, corresponding to Sa which is the adjustable amount of the mill outlet temperature, the expected improvement value is calculated as ΔEa = fa(Sa). Here, fa is the function for calculating the expected improvement value ΔEa from the adjustable amount Sa. Corresponding to Sb which is the adjustable amount of the conveying gas flow rate, the expected improvement value is calculated as ΔEb = fb(Sb). Corresponding to Sc which is the adjustable amount of the boiler outlet oxygen concentration, the expected improvement value is calculated as ΔEc = fc(Sc). Corresponding to Sd which is the adjustable amount of the auxiliary gas flow rate, the expected improvement value is calculated as ΔEd = fd(Sd).

[0108] Next, the driving parameters for which adjustment processing is to be performed are selected (S203). Specifically, it is determined whether the largest value among the improvement expected values corresponding to each driving parameter (MAX(ΔEa, ΔEb, ΔEc, ΔEd)) is greater than the threshold value (Eth(i)). That is, in the determination process of S203, the determination process of MAX(ΔEa, ΔEb, ΔEc, ΔEd)>Eth(i) is performed. Note that i is the number of repetitions, and 1 is set as the initial value.

[0109] When S203 is a negative determination (NO determination), S205 is executed.

[0110] When S203 is an affirmative determination (YES determination), adjustment processing is executed on the driving parameter corresponding to the largest value among the improvement expected values corresponding to each driving parameter (MAX(ΔEa, ΔEb, ΔEc, ΔEd)) (S204). In this way, adjustment processing is executed on the driving parameter with a large influence degree (improvement expected value) on the evaluation index (boiler efficiency).

[0111] Then, it is determined whether the process is finished (S205). Whether the process is finished is determined by whether i, which is the number of repetitions, has reached a predetermined upper limit value. For example, when the upper limit value is set to 4, the processes from S201 to S205 are performed 4 times. Note that for S205, the determination may also be made based on an end instruction from the driver or the like.

[0112] When the process is finished (YES determination in S205), the process is terminated. On the other hand, when the process is not finished (NO determination in S205), a process of adding 1 to i (i = i + 1) is performed (S206). Then, the process is executed again from S201.

[0113] Note that when i changes, the value of Eth(i) changes. Specifically, it is preferable that Eth(i) decreases as i increases. When decreasing Eth(i), for example, a predetermined amount is subtracted from the value. Note that Eth(i) may be a fixed value as Eth without using i as a variable.

[0114] By performing the processing in this way, adjustment processing for improving the boiler efficiency is executed from the operation parameters with a large expected improvement value as the degree of influence. As a result, the boiler efficiency is improved.

[0115] As described above, according to the operation state improvement system, power generation plant, operation state improvement method, and operation state improvement program according to the present embodiment, since the adjustment processing of the operation parameters is executed based on the degree of influence on the boiler efficiency, it is possible to effectively improve the boiler efficiency.

[0116] The present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the invention. It is also possible to combine the respective embodiments. That is, it is also possible to combine the above-described first embodiment and second embodiment.

[0117] The operation state improvement system, power generation plant, operation state improvement method, and operation state improvement program described in each of the above-described embodiments can be understood as follows, for example. The operation state improvement system (200) according to the present disclosure has a preset adjustable range for a predetermined operation parameter, and adjusts the operation parameter within the adjustable range based on a predetermined evaluation index based on the operation state of the boiler (10). It includes an adjustment unit (203).

[0118] According to the operation state improvement system (200) according to the present disclosure, within the adjustable range, the operation parameter is adjusted based on a predetermined evaluation index based on the operation state of the boiler (10). Therefore, it is possible to adjust the operation parameter to improve the evaluation index and the like. And since it is an adjustment of the operation parameter within the adjustable range, it is possible to suppress the operation parameter for improving the evaluation index and the like from being set to an inappropriate value. For example, compared with the method of optimizing the operation parameter using AI, it is expected to omit the introduction cost of AI and the verification of reproducibility by the model.

[0119] In the operating state improvement system (200) according to the present disclosure, the evaluation index may be the amount of improvement in boiler efficiency.

[0120] According to the operating state improvement system (200) according to the present disclosure, by using the amount of improvement in boiler efficiency as an evaluation index, it becomes possible to adjust the operation parameters to improve the boiler efficiency.

[0121] In the operating state improvement system (200) according to the present disclosure, the amount of improvement in the boiler efficiency is calculated based on the change in a predetermined operating state value before and after the adjustment of the operation parameters, and the operating state value is the oxygen concentration of the combustion gas discharged from the boiler (10), and the temperature of the combustion gas discharged from the air preheater (42) that performs heat exchange between the combustion gas and the air supplied to the boiler (10). It may also be.

[0122] According to the operating state improvement system (200) according to the present disclosure, based on the oxygen concentration of the combustion gas discharged from the boiler (10) and the temperature of the combustion gas discharged from the air preheater (42) that performs heat exchange between the combustion gas and the air supplied to the boiler (10), the amount of improvement in boiler efficiency can be calculated efficiently.

[0123] In the operating state improvement system (200) according to the present disclosure, the operation parameters may be preset based on the degree of influence on the evaluation index.

[0124] According to the operating state improvement system (200) according to the present disclosure, by setting the operation parameters based on the degree of influence on the evaluation index, it becomes possible to effectively adjust the operation parameters with respect to the evaluation index.

[0125] In the operating state improvement system (200) according to the present disclosure, when using a plurality of the operation parameters for the adjustment unit (203), the adjustment may be performed in order from the operation parameter having a large degree of influence on the evaluation index.

[0126] According to the operation state improvement system (200) according to the present disclosure, by sequentially adjusting the operation parameters having a large influence on the evaluation index, the adjustment of the operation parameters having a large influence is preferentially performed, and it is possible to efficiently perform the adjustment to the evaluation index.

[0127] The operation state improvement system (200) according to the present disclosure may be at least any one of the mill outlet temperature which is the temperature of the fluid discharged from the mills (31, 32, 33, 34, 35), the conveying gas flow rate which is the flow rate of the conveying gas supplied to the mills (31, 32, 33, 34, 35), the boiler outlet oxygen concentration which is the oxygen concentration of the combustion gas discharged from the boiler (10), and the auxiliary gas flow rate which is the flow rate of the auxiliary gas supplied to the stopped mills when a plurality of the mills (31, 32, 33, 34, 35) are provided for the boiler (10).

[0128] According to the operation state improvement system (200) according to the present disclosure, by using any one of the mill outlet temperature, the conveying gas flow rate, the boiler outlet oxygen concentration, and the auxiliary gas flow rate as the operation parameter, it is possible to effectively perform the adjustment to the evaluation index (boiler efficiency).

[0129] In the operation state improvement system (200) according to the present disclosure, when the adjustment unit (203) uses the mill outlet temperature, the conveying gas flow rate, the boiler outlet oxygen concentration, and the auxiliary gas flow rate as the operation parameters, the operation parameters may be adjusted in the order of the boiler outlet oxygen concentration, the mill outlet temperature, the conveying gas flow rate, and the auxiliary gas flow rate.

[0130] According to the operation state improvement system (200) according to the present disclosure, by adjusting the operation parameters in the order of the boiler outlet oxygen concentration, the mill outlet temperature, the conveying gas flow rate, and the auxiliary gas flow rate, it is possible to preferentially perform the adjustment of the operation parameters having a large influence on the evaluation index (boiler efficiency). Therefore, it is possible to efficiently perform the adjustment to the evaluation index (boiler efficiency).

[0131] In the operation state improvement system (200) according to the present disclosure, when adjusting the mill outlet temperature, the adjusting unit (203) increases the mill outlet temperature, when adjusting the conveying gas flow rate, the adjusting unit (203) decreases the conveying gas flow rate, when adjusting the boiler outlet oxygen concentration, the adjusting unit (203) decreases the boiler outlet oxygen concentration, and when adjusting the auxiliary gas flow rate, the adjusting unit (203) may decrease the auxiliary gas flow rate.

[0132] According to the operation state improvement system (200) according to the present disclosure, by increasing the mill outlet temperature when adjusting the mill outlet temperature, decreasing the conveying gas flow rate when adjusting the conveying gas flow rate, decreasing the boiler outlet oxygen concentration when adjusting the boiler outlet oxygen concentration, and decreasing the auxiliary gas flow rate when adjusting the auxiliary gas flow rate, it is possible to efficiently adjust the evaluation index (boiler efficiency).

[0133] In the operation state improvement system (200) according to the present disclosure, when using a plurality of the operation parameters, the adjusting unit (203) may not perform an adjustment on the operation parameter whose adjustable amount in the settable range is smaller than the threshold value.

[0134] According to the operation state improvement system (200) according to the present disclosure, it is possible to efficiently adjust the evaluation index (boiler efficiency).

[0135] In the operation state improvement system (200) according to the present disclosure, the adjusting unit (203) may repeatedly perform the adjustment of each operation parameter in the order.

[0136] According to the operation state improvement system (200) according to the present disclosure, by repeatedly performing the adjustment of each operation parameter, it is possible to more reliably perform the adjustment on the evaluation index.

[0137] The power generation plant (1) according to the present disclosure includes a boiler (10), a turbine (110) driven by steam generated by the boiler, and the above-described operation state improvement system (200).

[0138] The operation state improvement method according to the present disclosure has a settable range preset for a predetermined operation parameter, and includes a step of adjusting the operation parameter within the settable range based on a predetermined evaluation index based on the operation state of the boiler (10).

[0139] The operation state improvement program according to the present disclosure has a settable range preset for a predetermined operation parameter, and causes a computer to execute a process of adjusting the operation parameter within the settable range based on a predetermined evaluation index based on the operation state of the boiler (10).

Explanation of Signs

[0140] 1: Boiler power generation plant (power generation plant) 10: Coal-fired boiler (boiler) 11: Firebox 12: Combustion device 13: Combustion gas passage 14: Flue 21: Burner 22: Burner 23: Burner 24: Burner 25: Burner 26: Pulverized coal supply pipe 27: Pulverized coal supply pipe 28: Pulverized coal supply pipe 29: Pulverized coal supply pipe 30: Pulverized coal supply pipe 31: Mill 32: Mill 33: Mill 34: Mill 35: Mill 36: Air box 37: Air duct 38A: Forced draft fan 38B: Primary air fan 39: Additional air port 40: Additional air duct 41: Gas duct 42: Air heater (air preheater) 43: Denitration device 44: Dust collector 46: Desulfurization device 50: Chimney 101: Furnace wall 102: First superheater (superheater) 103: Second superheater (superheater) 104: Third superheater (superheater) 105: First reheater (reheater) 106: Second reheater (reheater) 107: Carbon saver 110: Steam turbine 111: High-pressure turbine 112: Medium-pressure turbine 113: Low-pressure turbine 114: Condenser 115: Generator 122: Low-pressure feedwater heater 123: Boiler feedwater pump 124: High-pressure feedwater heater 126: Steam separator 127: Steam separator drain tank 200: Control device (operation state improvement system) 201: Adjustment confirmation part 202: Evaluation part 203: Adjustment part 1100: CPU 1200: ROM 1300: RAM 1400: Hard disk drive 1500: Communication part 1800: Bus CA1: Area CA2: Area L1: Feedwater line L2: Drain water line L3: Steam line L4: Line L5: Steam Line L6: Circulation Line R1~R5: Cold Air Damper W1~W5: Hot Air Damper

Claims

1. an adjustment unit that adjusts a settable range for a predetermined operating parameter within the settable range based on a predetermined evaluation index based on an operating state of the boiler; The evaluation index is an improvement in boiler efficiency, the operating parameter is at least one of a mill outlet temperature, which is the temperature of a fluid discharged from the mill; a carrier gas flow rate, which is the flow rate of a carrier gas supplied to the mill; a boiler outlet oxygen concentration, which is the oxygen concentration of a combustion gas discharged from the boiler; and an auxiliary gas flow rate, which is the flow rate of an auxiliary gas supplied to a stopped mill when a plurality of the mills are provided for the boiler and one of the mills is stopped; The adjustment unit is an operational condition improvement system that adjusts each of the operational parameters in the order of the boiler outlet oxygen concentration, the mill outlet temperature, the conveying gas flow rate, and the auxiliary gas flow rate when the mill outlet temperature, the conveying gas flow rate, the boiler outlet oxygen concentration, and the auxiliary gas flow rate are used as the operational parameters.

2. The improvement amount of the boiler efficiency is calculated based on a change in a predetermined operational state value before and after the adjustment of the operational parameter, The operating condition improvement system according to claim 1, wherein the operating condition value is the oxygen concentration of the combustion gas discharged from the boiler and the temperature of the combustion gas discharged from an air preheater that performs heat exchange between the combustion gas and air supplied to the boiler.

3. The driving condition improving system according to claim 1 or 2, wherein the driving parameters are preset based on their influence on the evaluation index.

4. The driving condition improving system according to claim 3 , wherein when a plurality of the driving parameters are used, the adjustment unit adjusts the driving parameters in order of increasing influence on the evaluation index.

5. The operating condition improvement system described in any one of claims 1 to 4, wherein the adjustment unit increases the mill outlet temperature when adjusting the mill outlet temperature, decreases the carrier gas flow rate when adjusting the carrier gas flow rate, decreases the boiler outlet oxygen concentration when adjusting the boiler outlet oxygen concentration, and decreases the auxiliary gas flow rate when adjusting the auxiliary gas flow rate.

6. The driving condition improvement system according to any one of claims 1 to 5, wherein when a plurality of driving parameters are used, the adjustment unit does not adjust the driving parameters whose adjustable amount in the settable range is smaller than a threshold value.

7. The driving condition improving system according to claim 1 , wherein the adjustment unit repeatedly adjusts each of the driving parameters in the order.

8. Boiler and A turbine driven by steam generated by the boiler; A driving condition improvement system according to any one of claims 1 to 7, A power plant comprising:

9. A settable range is set in advance for a predetermined operating parameter, and the operating parameter is adjusted within the settable range based on a predetermined evaluation index based on an operating state of the boiler, The evaluation index is an improvement in boiler efficiency, the operating parameter is at least one of a mill outlet temperature, which is the temperature of a fluid discharged from the mill; a carrier gas flow rate, which is the flow rate of a carrier gas supplied to the mill; a boiler outlet oxygen concentration, which is the oxygen concentration of a combustion gas discharged from the boiler; and an auxiliary gas flow rate, which is the flow rate of an auxiliary gas supplied to a stopped mill when a plurality of the mills are provided for the boiler and one of the mills is stopped; The adjusting step is a method for improving an operational condition, in which, when the mill outlet temperature, the conveying gas flow rate, the boiler outlet oxygen concentration, and the auxiliary gas flow rate are used as the operational parameters, each of the operational parameters is adjusted in the order of the boiler outlet oxygen concentration, the mill outlet temperature, the conveying gas flow rate, and the auxiliary gas flow rate.

10. A settable range is set in advance for a predetermined operating parameter, and a computer is caused to execute a process of adjusting the operating parameter within the settable range based on a predetermined evaluation index based on an operating state of the boiler; The evaluation index is an improvement in boiler efficiency, the operating parameter is at least one of a mill outlet temperature, which is the temperature of a fluid discharged from the mill; a carrier gas flow rate, which is the flow rate of a carrier gas supplied to the mill; a boiler outlet oxygen concentration, which is the oxygen concentration of a combustion gas discharged from the boiler; and an auxiliary gas flow rate, which is the flow rate of an auxiliary gas supplied to a stopped mill when a plurality of the mills are provided for the boiler and one of the mills is stopped; The adjustment process is an operational condition improvement program that adjusts each of the operational parameters in the order of the boiler outlet oxygen concentration, the mill outlet temperature, the conveying gas flow rate, and the auxiliary gas flow rate when the mill outlet temperature, the conveying gas flow rate, the boiler outlet oxygen concentration, and the auxiliary gas flow rate are used as the operational parameters.

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