JP7585698B2 - FUEL SUPPLY AMOUNT CONTROL DEVICE, BOILER SYSTEM, AND FUEL SUPPLY AMOUNT CONTROL METHOD - Google Patents

Description

This disclosure relates to a fuel supply amount control device, a boiler system, and a fuel supply amount control method.

In recent years, technology has been developed to burn biomass fuel in addition to coal in boilers in order to reduce carbon dioxide emissions (for example, Patent Document 1).

JP 2011-106790 A

When mixing multiple types of solid fuels with different heat values, such as the coal and biomass fuels described in Patent Document 1, there is a need to develop technology that controls the supply flow rate to the boiler for each solid fuel so that a preset heat value mixing ratio (mixing ratio converted into heat value) is achieved.

In view of these problems, the present disclosure aims to provide a fuel supply amount control device, a boiler system, and a fuel supply amount control method that are capable of controlling the supply flow rate to a boiler for each solid fuel so as to achieve a preset heat mixing ratio.

In order to solve the above problems, a fuel supply amount control device according to one embodiment of the present disclosure includes a first flow rate calculation unit that calculates the flow rate of the first solid fuel to be supplied to the boiler based on a fuel flow rate command value, which is a target flow rate of the first solid fuel for the boiler, and a heat quantity co-combustion ratio of the first solid fuel and the second solid fuel to be supplied to the boiler, and a second flow rate calculation unit that calculates the flow rate of the second solid fuel to be supplied to the boiler based on the flow rate of the first solid fuel , the heat quantity co-combustion ratio, the heat quantity of the first solid fuel, and the heat quantity of the second solid fuel calculated by the first flow rate calculation unit , wherein the first solid fuel is coal and the second solid fuel is biomass fuel .

The first flow rate calculation unit may also calculate the flow rate of the first solid fuel based on the fuel flow rate command value, the heat mixing ratio, and the number of first fuel supply units that supply the first solid fuel to the boiler.

The heat quantity mixed combustion ratio is the ratio of the heat quantity of the second solid fuel to the heat quantity of the first solid fuel and the second solid fuel, and the first flow rate calculation unit may calculate the flow rate of the first solid fuel based on formula (A): Flow rate of the first solid fuel = fuel flow rate command value × {(100 - heat quantity mixed combustion ratio)/100}/number of first fuel supply units.

In addition, the second flow rate calculation unit may calculate the flow rate of the second solid fuel based on the number of second fuel supply units that supply the second solid fuel to the boiler, in addition to the flow rate and heat mixing ratio of the first solid fuel calculated by the first flow rate calculation unit.

In addition, the heat quantity co-combustion ratio is the ratio of the heat quantity of the second solid fuel to the heat quantity of the first solid fuel and the second solid fuel, and the second flow rate calculation unit calculates the flow rate of the second solid fuel by multiplying the calculated flow rate of the first solid fuel by a correction value, and the correction value may be calculated based on: correction value = {heat quantity co-combustion ratio/(100-heat quantity co-combustion ratio)} x (heat quantity of first solid fuel/heat quantity of second solid fuel) x (number of first fuel supply units/number of second fuel supply units) ... formula (B).

In order to solve the above problems, a boiler system according to one embodiment of the present disclosure includes a boiler, a first fuel supply unit that supplies a first solid fuel to the boiler, a second fuel supply unit that supplies a second solid fuel to the boiler, a first flow rate calculation unit that calculates a flow rate of the first solid fuel to be supplied to the boiler based on a fuel flow rate command value that is a target flow rate of the first solid fuel for the boiler and a heat quantity co-combustion ratio of the first solid fuel and the second solid fuel to be supplied to the boiler, and a second flow rate calculation unit that calculates the flow rate of the second solid fuel to be supplied to the boiler based on the flow rate of the first solid fuel , the heat quantity co-combustion ratio, the heat quantity of the first solid fuel, and the heat quantity of the second solid fuel calculated by the first flow rate calculation unit , wherein the first solid fuel is coal and the second solid fuel is biomass fuel .

The first fuel supply unit may also include a crushing unit that crushes the first solid fuel, and the second fuel supply unit may also include a crushing unit that crushes the second solid fuel.

In order to solve the above problems, a fuel supply amount control method according to one embodiment of the present disclosure includes a step of calculating a flow rate of a first solid fuel to be supplied to the boiler based on a fuel flow rate command value, which is a target flow rate of a first solid fuel for the boiler, and a heat capacity co-combustion ratio of the first solid fuel and the second solid fuel to be supplied to the boiler, and a step of calculating a flow rate of a second solid fuel to be supplied to the boiler based on the calculated flow rate of the first solid fuel, the heat capacity co-combustion ratio, the heat capacity of the first solid fuel, and the heat capacity of the second solid fuel , wherein the first solid fuel is coal and the second solid fuel is biomass fuel .

According to the present disclosure, it is possible to control the supply flow rate to the boiler for each solid fuel so as to achieve a preset heat mixing ratio.

FIG. 1 is a diagram illustrating a boiler system according to an embodiment. FIG. 2 is a diagram illustrating a target flow rate calculation unit according to the embodiment. FIG. 3 is a diagram illustrating an output correction unit according to the embodiment. FIG. 4 is a flowchart illustrating a process flow of the fuel supply amount control method according to the embodiment.

The embodiments of the present disclosure will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific values shown in the embodiments are merely examples for ease of understanding, and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid duplicated explanations, and elements not directly related to the present disclosure are not illustrated.

[Boiler system 100]
Fig. 1 is a diagram illustrating a boiler system 100 according to this embodiment. In Fig. 1, dashed arrows indicate flows of coal, biomass fuel, and steam. In Fig. 1, solid arrows indicate flows of signals.

As shown in FIG. 1, the boiler system 100 includes a fuel supply unit 110, a boiler 120, a turbine 130, a generator 140, and a fuel supply amount control device 200. In this embodiment, the boiler system 100 includes three fuel supply units 110.

The fuel supply unit 110 supplies solid fuel to the boiler 120. The fuel supply unit 110 includes a transport unit 112 and a crushing unit 114. The transport unit 112 is, for example, a conveyor. The transport unit 112 transports the solid fuel from a storage site to the crushing unit 114. The crushing unit 114 (mill) crushes the solid fuel. The crushed solid fuel is transported by air current to the boiler 120.

In this embodiment, of the three fuel supply units 110, two fuel supply units 110 function as fuel supply units 110A (first fuel supply units) that supply coal (first solid fuel) to the boiler 120. The remaining fuel supply unit 110 functions as fuel supply unit 110B (second fuel supply unit) that supplies biomass fuel (second solid fuel) to the boiler 120.

The fuel supply unit 110A supplies coal according to the mill master command MMD [t/h] output from the fuel supply amount control device 200 described below.

The coal is one of the following: anthracite, semi-anthracite, bituminous coal, sub-bituminous coal, and lignite.

The fuel supply unit 110B supplies biomass fuel according to the biomill master command BMMD [t/h] output from the fuel supply amount control device 200.

Biomass fuel is one or more of woody biomass, herbaceous biomass, and waste biomass processed into pellets. Woody biomass is, for example, wood chips, sawdust, bark, etc. Herbaceous biomass is, for example, wheat straw, rice straw, etc. Waste biomass is, for example, palm kernel shells (PKS) and empty fruit bunches (EFB), which are generated as a result of producing palm oil from palm.

The boiler 120 burns a mixture of coal and biomass fuel. The boiler 120 generates steam using the heat of combustion. The steam is guided to the turbine 130. The turbine 130 converts the energy contained in the steam into rotational energy. The generator 140 is coaxially connected to the turbine 130. The generator 140 generates electricity using the rotational energy transmitted from the turbine 130.

The fuel supply amount control device 200 is composed of a semiconductor integrated circuit including a CPU (central processing unit). The fuel supply amount control device 200 reads programs and parameters for operating the CPU itself from the ROM.

In this embodiment, the fuel supply amount control device 200 functions as a target flow rate calculation unit 210, a first flow rate calculation unit 220, a correction value calculation unit 230, and an output correction unit 240.

The target flow rate calculation unit 210 calculates the target flow rate FRT [t/h] based on the fuel flow rate command value FRD and the actual fuel flow rate FRC. The fuel flow rate command value FRD is a value determined for the boiler 120. The fuel flow rate command value FRD is a command value [t/h] indicating the flow rate of coal to be supplied to the boiler 120 required to satisfy the target power generation amount by the generator 140. In other words, the fuel flow rate command value FRD is a command value indicating the flow rate of coal that satisfies the target power generation amount when the boiler 120 is operated with 100% coal. The actual fuel flow rate FRC is a value obtained by converting the flow rate [t/h] of the solid fuel (coal and biomass fuel) currently supplied to the boiler 120 into the coal flow rate.

2 is a diagram illustrating the target flow rate calculation unit 210 according to this embodiment. As shown in FIG. 2, the target flow rate calculation unit 210 includes a subtraction unit 212 and a PI adjustment unit 214. The subtraction unit 212 calculates the difference (deviation) between the fuel flow rate command value FRD and the actual fuel flow rate FRC. In this embodiment, the subtraction unit 212 subtracts the actual fuel flow rate FRC from the fuel flow rate command value FRD. The PI adjustment unit 214 changes the output value (target flow rate FRT) by PI control so that the deviation calculated by the subtraction unit 212 becomes 0 (zero). The PI adjustment unit 214 outputs the target flow rate FRT to the first flow rate calculation unit 220.

Returning to FIG. 1, the first flow rate calculation unit 220 calculates the flow rate (mill master command MMD) [t/h] of coal to be supplied from one fuel supply unit 110A to the boiler 120 based on the target flow rate FRT, the heat mixed-firing ratio [%], and the number of fuel supply units 110A (here, 2).

In the present embodiment, the first flow rate calculation unit 220 calculates the mill master command MMD from the following formula (1).
Mill master command MMD=target flow rate FRT×{(100−heat amount mixed combustion ratio)/100}/number of fuel supply units 110A...Equation (1)
The heat quantity mixed-combustion ratio is the ratio of the heat quantity of the biomass fuel to the heat quantity of the coal and the biomass fuel (the heat quantity of the entire solid fuel supplied to the boiler 120). The heat quantity mixed-combustion ratio is a value that is set in advance.

The mill master command MMD calculated by the first flow rate calculation unit 220 is output to each of the multiple output correction units 240.

The correction value calculation unit 230 calculates a correction value CV for correcting the mill master command MMD. The correction value calculation unit 230 calculates the correction value CV from the following formula (2).
Correction value CV={heat quantity mixed-combustion ratio/(100-heat quantity mixed-combustion ratio)}×(heat quantity of coal/heat quantity of biomass fuel)×(number of fuel supply units 110A/number of fuel supply units 110B) (Equation (2))
The calorific value of the coal [kJ/kg] and the calorific value of the biomass fuel [kJ/kg] are values that are measured in advance by calorific analysis, etc. The correction value CV calculated by the correction value calculation unit 230 is output to each of the multiple output correction units 240.

The output correction units 240 are provided in the same number as the fuel supply units 110 (three in this example). In FIG. 1, the output correction unit 240A indicates the output correction unit 240 that outputs the flow rate to the fuel supply unit 110A. In FIG. 2, the output correction unit 240B indicates the output correction unit 240 that outputs the flow rate to the fuel supply unit 110B.

The output correction unit 240 corrects the input mill master command MMD when the output destination is the fuel supply unit 110B.

3 is a diagram illustrating the output correction unit 240 according to the present embodiment. As shown in FIG. 3, the output correction unit 240 includes an input switching unit 242, a change rate limiting unit 244, and a multiplying unit 246.

The input switching unit 242 receives the correction value CV and the fixed value FV (here, 1.0). The input switching unit 242 switches the input value depending on the output destination of the output correction unit 240. In this embodiment, when the output destination is the fuel supply unit 110A, that is, the input switching unit 242 of the output correction unit 240A, the input switching unit 242 switches the input to the fixed value FV. When the output destination is the fuel supply unit 110B, that is, the input switching unit 242 of the output correction unit 240B, the input switching unit 242 switches the input to the correction value CV. The input switching unit 242 then outputs the input value to the change rate limiting unit 244.

The change rate limiting unit 244 limits the change rate (rate of increase and rate of decrease) of the input value and outputs it. For example, when the fixed value FV is less than the correction value CV and the input value switches from the fixed value FV to the correction value CV, the change rate limiting unit 244 gradually increases the output value at a constant rate of increase from the fixed value FV to the correction value CV. Also, when the fixed value FV is less than the correction value CV and the input value switches from the correction value CV to the fixed value FV, the change rate limiting unit 244 gradually decreases the output value at a constant rate of decrease from the correction value CV to the fixed value FV. By providing the change rate limiting unit 244, it is possible to stabilize the fuel supply unit 110.

The multiplication unit 246 multiplies the output of the rate of change limiting unit 244 by the mill master command MMD. In other words, when the output correction unit 240 functions as the output correction unit 240A, the multiplication unit 246 multiplies the mill master command MMD by the fixed value FV. Therefore, the output correction unit 240A outputs the mill master command MMD as is to the fuel supply unit 110A.

On the other hand, when the output correction unit 240 functions as the output correction unit 240B, the multiplication unit 246 multiplies the mill master command MMD by the correction value CV. Therefore, the output correction unit 240B outputs the biomill master command BMMD [t/h] obtained by multiplying the mill master command MMD by the correction value CV to the fuel supply unit 110B. In other words, the output correction unit 240B functions as a second flow rate calculation unit that calculates the flow rate of the biomass fuel (biomill master command BMMD) to be supplied to the boiler 120 based on the target flow rate FRT, the heat amount mixed combustion ratio, the heat amount of the coal, the heat amount of the biomass fuel, and the number of the fuel supply units 110B (here, 1).

[Fuel supply amount control method]
Also provided is a fuel supply amount control method using the above-mentioned fuel supply amount control device 200. Fig. 4 is a flowchart showing a process flow of the fuel supply amount control method according to this embodiment. As shown in Fig. 4, the fuel supply amount control method includes a first flow rate calculation step S110, a first flow rate output step S120, a correction value calculation step S130, and a second flow rate output step S140.

[First flow rate calculation step S110]
In the first flow rate calculation step S110, the first flow rate calculation unit 220 calculates a mill master amount of fuel to be supplied from one fuel supply unit 110A to the boiler 120 based on the target flow rate FRT, the heat amount mixed combustion ratio, and the number of fuel supply units 110A. This is a process for calculating the command MMD.

[First flow rate output step S120]
The first flow rate output step S120 is a step in which the output correction unit 240A outputs the mill master command MMD calculated in the first flow rate calculation step S110 to the fuel supply unit 110A.

[Correction value calculation step S130]
The correction value calculation step S130 is a step in which the correction value calculation unit 230 calculates a correction value CV based on the heat quantity co-firing ratio, the heat quantity of coal, the heat quantity of biomass fuel, the number of fuel supply units 110A, and the number of fuel supply units 110B.

[Second flow rate output step S140]
In the second flow rate output process S140, first, the output correction unit 240B multiplies the mill master command MMD calculated in the first flow rate calculation process S110 by the correction value CV calculated in the correction value calculation process S130 to obtain the biomill The output correction unit 240B then outputs the calculated biomill master command BMMD to the fuel supply unit 110B.

As described above, the fuel supply amount control device 200 according to this embodiment and the fuel supply amount control method using the same make it possible to control the supply flow rate to the boiler 120 for each solid fuel so as to achieve a preset heat mixing ratio.

The fuel supply amount control device 200 also includes a correction value calculation unit 230 and an output correction unit 240B. This allows the fuel supply amount control device 200 to calculate the biomill master command BMMD by a simple process of simply multiplying the mill master command MMD by the correction value CV.

The fuel supply amount control device 200 also includes an output correction unit 240 having an input switching unit 242. This allows the fuel supply amount control device 200 to easily switch the output value when the solid fuel supplied to the fuel supply unit 110 is switched from coal to biomass fuel, or when the solid fuel supplied to the fuel supply unit 110 is switched from biomass fuel to coal.

Although the embodiments have been described above with reference to the attached drawings, it goes without saying that the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

For example, in the above-described embodiment, coal is given as an example of the first solid fuel, and biomass fuel is given as an example of the second solid fuel. However, there is no limitation on the type of the first solid fuel and the second solid fuel as long as they have different unit heat quantities. For example, the first solid fuel and the second solid fuel may be different types of biomass fuel (e.g., wood-based biomass and waste-based biomass).

In the above embodiment, the fuel supply unit 110 is provided with the pulverizing unit 114. However, the fuel supply unit 110 does not need to be provided with the pulverizing unit 114. For example, if the boiler 120 is a circulating fluidized bed boiler (CFB boiler), the fuel supply unit 110 does not need to be provided with the pulverizing unit 114.

In the above embodiment, the first flow rate calculation unit 220 calculates the mill master command MMD based on the fuel flow rate command value, the heat amount co-firing ratio, and the number of fuel supply units 110A. However, when there is one fuel supply unit 110A, the first flow rate calculation unit 220 may calculate the mill master command MMD based on the fuel flow rate command value and the heat amount co-firing ratio. Similarly, in the above embodiment, the correction value calculation unit 230 calculates the correction value CV based on the heat amount co-firing ratio, the heat amount of coal, the heat amount of biomass fuel, the number of fuel supply units 110A, and the number of fuel supply units 110B. However, when there are the same number of fuel supply units 110A and fuel supply units 110B, the correction value calculation unit 230 may calculate the correction value CV based on the heat amount co-firing ratio, the heat amount of coal, and the heat amount of biomass fuel.

Also, in the above embodiment, an example was given of the case where the output correction unit 240B functioning as the second flow rate calculation unit calculates the biomill master command BMMD by multiplying the mill master command MMD calculated by the first flow rate calculation unit 220 by the correction value CV. However, there is no limitation on the calculation method of the second flow rate calculation unit as long as it can calculate the biomill master command BMMD based on the fuel flow rate command value FRD (target flow rate FRT), the heat amount co-combustion ratio, the heat amount of the first solid fuel, the heat amount of the second solid fuel, and the number of fuel supply units 110B.

For example, the second flow rate calculation unit may calculate the biomill master command BMMD based on the following formula (3):

Biomill master command BMMD = target flow rate FRT x (calorific value mixed combustion ratio/100) x (calorific value of coal/calorific value of biomass fuel)/number of fuel supply units 110B ... formula (3)

In addition, when there is one fuel supply unit 110B, the second flow rate calculation unit may calculate the flow rate of the second solid fuel based on the fuel flow rate command value, the heat amount mixed combustion ratio, the heat amount of the coal, and the heat amount of the biomass fuel.

In the above embodiment, the heat amount mixing ratio is the ratio of the heat amount of the second solid fuel to the heat amount of the first solid fuel and the second solid fuel. However, the heat amount mixing ratio may be the ratio of the heat amount of the first solid fuel to the heat amount of the first solid fuel and the second solid fuel. In this case, the first flow rate calculation unit 220 calculates
Flow rate of first solid fuel=Fuel flow rate command value×(Heat mixed combustion ratio/100)/Number of first fuel supply units Equation (4)
The flow rate of the first solid fuel may be calculated based on the above.

Similarly, the correction value calculation unit 230
Correction value={(100−heat amount mixed-combustion ratio)/heat amount mixed-combustion ratio}×(heat amount of first solid fuel/heat amount of second solid fuel)×(number of first fuel supply units/number of second fuel supply units) (Equation (5))
The correction value may be calculated based on the above.

This disclosure can be used in fuel supply amount control devices, boiler systems, and fuel supply amount control methods.

100 Boiler system 110A Fuel supply unit (first fuel supply unit)
110B Fuel supply section (second fuel supply section)
114 Crushing section 200 Fuel supply amount control device 220 First flow rate calculation section 240B Output correction section (second flow rate calculation section)

Claims (8)

a first flow rate calculation unit that calculates a flow rate of the first solid fuel to be supplied to the boiler based on a fuel flow rate command value that is a target flow rate of the first solid fuel for the boiler and a heat mixed-combustion ratio of the first solid fuel and a second solid fuel to be supplied to the boiler;
a second flow rate calculation unit that calculates a flow rate of the second solid fuel to be supplied to the boiler based on the flow rate of the first solid fuel , the heat amount mixed combustion ratio, the heat amount of the first solid fuel, and the heat amount of the second solid fuel calculated by the first flow rate calculation unit;
Equipped with
A fuel supply amount control device , wherein the first solid fuel is coal and the second solid fuel is biomass fuel . The fuel supply amount control device according to claim 1, wherein the first flow rate calculation unit calculates the flow rate of the first solid fuel based on the fuel flow rate command value, the heat amount mixed combustion ratio, and the number of first fuel supply units that supply the first solid fuel to the boiler. the heat amount mixed combustion ratio is a ratio of a heat amount of the second solid fuel to a heat amount of the first solid fuel and the second solid fuel,
The first flow rate calculation unit is
Flow rate of first solid fuel=Fuel flow rate command value×{(100−heat amount mixed combustion ratio)/100}/Number of first fuel supply units (Equation (A))
The fuel supply amount control device according to claim 2 , wherein the flow rate of the first solid fuel is calculated based on the above formula: 4. The fuel supply amount control device according to claim 1, wherein the second flow rate calculation unit calculates the flow rate of the second solid fuel based on the number of second fuel supply units that supply the second solid fuel to the boiler, in addition to the flow rate of the first solid fuel and the heat mixed-combustion ratio calculated by the first flow rate calculation unit. the heat amount mixed combustion ratio is a ratio of a heat amount of the second solid fuel to a heat amount of the first solid fuel and the second solid fuel,
the second flow rate calculation unit multiplies the calculated flow rate of the first solid fuel by a correction value to calculate a flow rate of the second solid fuel;
The correction value is
Correction value={heat amount mixed-combustion ratio/(100-heat amount mixed-combustion ratio)}×(heat amount of first solid fuel/heat amount of second solid fuel)×(number of first fuel supply units/number of second fuel supply units) ... formula (B)
5. The fuel supply amount control device according to claim 1, wherein the fuel supply amount is calculated based on the above. Boiler and
A first fuel supply unit that supplies a first solid fuel to the boiler;
A second fuel supply unit that supplies a second solid fuel to the boiler;
a fuel supply amount control device including : a first flow rate calculation unit that calculates a flow rate of the first solid fuel to be supplied to the boiler based on a fuel flow rate command value that is a target flow rate of the first solid fuel for the boiler and a heat amount co-combustion ratio of the first solid fuel and the second solid fuel to be supplied to the boiler; and a second flow rate calculation unit that calculates the flow rate of the second solid fuel to be supplied to the boiler based on the flow rate of the first solid fuel, the heat amount co-combustion ratio, the heat amount of the first solid fuel, and the heat amount of the second solid fuel calculated by the first flow rate calculation unit;
Equipped with
A boiler system , wherein the first solid fuel is coal and the second solid fuel is a biomass fuel . the first fuel supply unit includes a crushing unit that crushes the first solid fuel,
The boiler system according to claim 6 , wherein the second fuel supply unit includes a pulverizer unit that pulverizes the second solid fuel. calculating a flow rate of the first solid fuel to be supplied to the boiler based on a fuel flow rate command value which is a target flow rate of the first solid fuel for the boiler and a heat mixed-combustion ratio of the first solid fuel and a second solid fuel to be supplied to the boiler;
calculating a flow rate of the second solid fuel to be supplied to the boiler based on the calculated flow rate of the first solid fuel , the heat amount mixed-combustion ratio, the heat amount of the first solid fuel, and the heat amount of the second solid fuel;
Including,
The fuel supply amount control method , wherein the first solid fuel is coal and the second solid fuel is biomass fuel .

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