JPH05322155A - Fuel supply control device in combustion device - Google Patents

Abstract

PURPOSE:To perform a stable fuel supply control against a load variation in which a phase displacement caused by a delay in responding speed between fine powder coal fuel and heavy oil fuel is eliminated and occurrence of distur bance is prevented. CONSTITUTION:A load distribution outputted from a load adjusting unit 10 is distributed by distributors 12 and 13 in response to a distribution rate alphaset in advance by a rate setting unit 11, the load instruction is given to a flow rate adjusting meter 14 of a fine powder coal control system and to a flow rate adjusting meter 15 of a heavy oil control system so as to control a fine powder coal flow rate and a heavy oil flow rate supplied to a boiler 1, respectively. Instruction values outputted from the flow rate adjusting meters 14 and 15 are given to a calculator 17, a real feeding rate beta of fine powder coal is calculated, this calculated value is given to a comparator 18, compared with the rate alpha set by the rate setting unit 11 so as to discriminate if the real feeding rate beta of fine powder coal is within a certain range in respect to a reference rate set by a rate setting unit. If the value is within the range, the load instruction inputted from the distributor 12 into the flow rate adjusting meter 14 is fixed by a holding unit 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control device for a combustion apparatus such as a co-firing type boiler and a heating furnace for simultaneously burning pulverized fuel such as pulverized coal and fluid fuel such as liquid or gas.

[0002]

2. Description of the Related Art Conventionally, for example, in a co-firing type boiler that simultaneously combusts pulverized coal and heavy oil to generate steam, the supply amount of these fuels is adjusted to keep the steam pressure constant.

FIG. 3 shows a fuel supply control system for such a boiler. In FIG. 3, reference numeral 1 denotes a boiler, and the boiler 1 is supplied with pulverized coal cut out from a tank 2 to a conveying section 3 by a blower 4 through a fuel conveying line 5, and a fuel supply line from a heavy oil tank side (not shown). The heavy oil is supplied through No. 6. In this case, a cutout amount control mechanism 8 that is driven by a motor 7 to control the cutout amount of pulverized coal is provided in the lower portion of the tank 2, and a flow rate control valve 9 is provided in the fuel supply line 6. ..

On the other hand, 10 is a load controller for issuing a load command for keeping the steam pressure generated from the boiler constant, that is, a fuel increase / decrease command. The fuel increase / decrease command issued from this load controller 10 is the ratio setter 11 It is input as a set value to the flow rate controllers 14 and 15 through the distributors 12 and 13 which distribute based on the standard mixed combustion rate set by. The flow rate controller 14 controls the amount of pulverized coal cut out by controlling the motor 7 based on the set value input from the distributor 12, and the flow rate controller 15 sets the set value input from the distributor 13. And the flow rate detected by the heavy oil flow rate detector 16 provided in the fuel supply line 6 is adjusted to adjust the flow rate control valve 8 to control the supply amount of heavy oil.

In the fuel supply control system of such a boiler, pulverized coal and heavy oil are supplied to the boiler 1 through the fuel supply line and the heavy oil supply line according to the same command issued from the load controller 10. Since the fuel is a powder fuel and a liquid fuel, a phase shift occurs due to the difference in the following speeds of fuel supply.

FIG. 4 shows a response waveform of each fuel in response to a fuel command. As you can see from this response waveform,
Pulverized coal has a better changeability than pulverized coal because it has a change in the amount conveyed by controlling the cut-out amount and changes in the flow rate of heavy oil due to pressure feeding.

[0007]

As described above, in the conventional fuel supply control device, the cutting amount of the pulverized coal and the supply flow rate of the heavy oil are controlled by the same command issued from the load controller 10. Due to a large difference in follow-up speed of fuel supply, a phase shift occurs until pulverized coal and heavy oil are supplied to the boiler 1, and as a result, disturbance causes control instability.

The present invention eliminates the phase shift due to the response delay of the time between the fine powder fuel and the fluid fuel such as liquid or gas to prevent the occurrence of disturbance and to stably control the fuel supply when the load changes. An object of the present invention is to provide a fuel supply control device for a combustion device that can be used.

[0009]

In order to achieve the above object, the present invention distributes a load command issued from a load controller based on a standard co-firing rate, and uses this as a set value to adjust the flow rate of a fine powder fuel control system. And a flow rate controller of the fluid fuel control system to control the flow rate of the fine powder fuel and the flow rate of the fluid fuel supplied to the combustion device, the flow rate controller of each fuel control system outputs The actual mixed combustion ratio of the fine fuel and the reference mixed combustion ratio are calculated by comparing the actual mixed combustion ratio of the fine fuel obtained by this calculator with the reference mixed combustion ratio. A comparator for determining whether or not it is within a certain range with respect to the rate, and the actual mixed combustion rate with respect to the reference mixed combustion rate provided by the comparator provided on the input side of the flow rate controller of the fine powder fuel control system. Determined to be within range It is obtained and a cage for fixing the set value input to the flow controllers of the pulverized fuel control system to be.

[0010]

In the fuel supply control device having such a structure, when the actual mixed combustion ratio calculated by the arithmetic unit is within a certain range with respect to the reference mixed combustion ratio, it is input to the flow rate controller of the fine powder fuel control system. Since the set value that is set is fixed, the frequency of changing the set value is reduced as much as possible, and the phase shift due to the response delay of the fine fuel and the fluid fuel is eliminated, so it is possible to prevent the occurrence of disturbance. Therefore, the combustion supply control that follows the load fluctuation can be stably performed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a system configuration diagram showing an example of a fuel supply control device for a combustion apparatus according to the present invention. The same parts as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. Here, only different points will be described. State.

In this embodiment, as shown in FIG. 1, the flow rate is adjusted.
Pulverized coal cutting amount command value output from total 14 and flow controller
Pulverized coal by incorporating the heavy oil flow rate command value output from 15
With the calculator 17 and the ratio setter 11 for obtaining the actual mixed burning rate of
Calculated by the standard co-firing rate of the pulverized coal set and the calculator 17.
The actual co-firing rate of the pulverized coal is compared to the actual co-firing rate of the pulverized coal.
Is within the specified range for the standard co-firing rate of pulverized coal
It is distributed by the comparator 18 and the distributor 12 for judging whether
The fuel increase / decrease command is input, and the comparator 18 mixes the pulverized coal.
The burning rate is within the specified range with respect to the standard mixed burning rate of pulverized coal
Retainer that fixes the fuel increase / decrease command load command when it is determined that
19 are provided respectively, and the pulverized coal flow rate control system is for coarse adjustment.
The heavy oil fuel flow control system to function as a fine adjustment.
It is a scam. Next, the fuel supply configured in this way
The operation of the feed control device will be described.

When the load controller 10 issues a fuel increase / decrease command so that the steam pressure generated from the boiler 1 is kept constant, the fuel increase / decrease command is distributed based on the reference mixed combustion rate set by the ratio setter 1. It is distributed by the devices 12 and 13 and is given to the flow controllers 14 and 15 as set values, respectively. In this case, the calculator 17 calculates the actual mixed combustion rate of the pulverized coal by A / (A + B) based on the flow rate increase / decrease commands A and B output from the flow rate controllers 14 and 15, and inputs the value to the comparator 18. To do. In this comparator 18, the actual mixed combustion rate β of the pulverized coal is compared with the reference mixed combustion rate α set by the ratio setting device 11, and the actual mixed combustion rate β of the pulverized coal is determined by the reference mixed combustion rate α.
For (a, -b) is determined whether or not,
If it is not within the range, a pulverized coal increase / decrease command based on the standard mixed combustion rate set by the ratio setter 11 is given to the flow rate controller 14 as a set value through the retainer 19 as in the conventional case. By giving a holding command to fix the pulverized coal increase / decrease command value input from the distributor 12, and by giving this to the flow rate controller 14 as a set value, the amount of pulverized coal cut out becomes constant.

Therefore, when the pulverized coal actual input ratio β is within a certain range (a, -b), only the flow controller 15 follows the heavy oil increase / decrease command distributed by the distributor 13 based on the standard mixed combustion rate. Then, by controlling the supply flow rate of the heavy oil, the steam pressure of the boiler 1 is controlled to the set value. As described above, the flow rate controller 14 of the pulverized coal control system functions for coarse adjustment, and the flow rate controller 15 of the heavy oil control system functions for fine adjustment.

FIG. 2 is a time chart showing the fuel increase / decrease command issued from the load controller 10 and the response of the flow controller 14 of the pulverized coal control system and the flow controller 15 of the heavy oil control system. As can be seen from this time chart, if the actual co-firing rate β of pulverized coal is within a certain range (a, -b) with respect to the reference co-firing rate α set by the ratio setter, the load command for coarse adjustment is set. Although there is no change, when it is outside a certain range (a, -b), the cut amount of pulverized coal is controlled so as to change at a constant speed.

Thus, in this embodiment, the load adjuster 10
The fuel increase / decrease command issued by the distributor is distributed by the distributors 12 and 13 based on the reference mixed combustion rate α set by the ratio setting device 11, and the flow controller 14 of the pulverized coal control system is used as the set value.
And the boiler 1 by giving it to the flow rate controller 15 of the heavy oil control system 1.
In the fuel supply control device for controlling the amount of cut pulverized coal and the flow rate of heavy oil supplied to the pulverized coal, the flow rate increase / decrease command values A and B output from the flow rate controllers 14 and 15 are given to the calculator 17 to determine the actual pulverized coal. The co-firing rate β is determined, and this is given to the comparator 18 and compared with the reference co-firing rate α set by the ratio setting device 11, and the actual co-firing rate β of the pulverized coal is within a range (a,
-B) is determined, and if it is within the range, the pulverized coal increase / decrease command value input as a set value from the distributor 12 to the flow rate controller 14 is fixed by the retainer 19. The frequency of changing the set value of the flow rate controller 14 of the pulverized coal control system can be reduced as much as possible, and the fuel increase / decrease command issued from the load controller 10 and the cut amount of the pulverized coal controlled by the flow rate controller 14 can be controlled. There is no phase shift between them, fuel supply control that follows load changes can be performed stably, and stable steam pressure can be obtained from the boiler 1.

[0018]

As described above, according to the present invention, the phase shift due to the response delay in time between the fine powder fuel and the fluid fuel such as liquid or gas is eliminated to prevent the occurrence of disturbance and to prevent the occurrence of disturbance. It is possible to provide a fuel supply control device for a combustion device that can stably perform fuel supply control.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an embodiment of a fuel supply control device according to the present invention.

FIG. 2 is a view showing a time chart for explaining the operation of the embodiment.

FIG. 3 is a system configuration diagram showing a conventional fuel supply control device.

FIG. 4 is a view showing a time chart for explaining the operation of the apparatus.

[Explanation of symbols]

1 ... boiler, 2 ... tank, 3 ... conveying section, 4 ... blower, 5 ... fuel conveying line, 6 ... fuel supply line,
7 ... Motor, 8 ... Cutting amount control mechanism, 9 ... Flow control valve, 10 ... Load controller, 1 ... Ratio setting device, 12, 1
3 ... Distributor, 14, 15 ... Flow rate controller, 16 ... Heavy oil flow rate detector, 17 ... Computing unit, 18 ... Comparator, 19
…… Cage.

Claims (1)

[Claims] 1. A combustor in which a load command issued from a load controller is distributed based on a reference co-firing rate and is given to a flow controller of a fine fuel control system and a flow controller of a fluid fuel control system as a set value. In the fuel supply control device for controlling the flow rate of the fine powder fuel and the flow rate of the fluid fuel supplied to the fuel cell, the control command values output from the flow rate controller of each fuel control system are respectively taken in to obtain the actual mixed combustion rate of the fine fuel powder. By comparing the actual mixed combustion rate of the pulverized fuel obtained by this arithmetic unit with the reference mixed combustion rate to determine whether the actual mixed combustion rate is within a certain range with respect to the reference mixed combustion rate. A comparator and the pulverized fuel control system is provided on the input side of the flow rate controller, and when the comparator determines that the actual co-firing rate is within a certain range with respect to the reference co-firing rate, the pulverized fuel control system Input to the flow controller And a retainer for fixing a set value.