JPH05240422A - Combustion air flow rate controller - Google Patents

Abstract

PURPOSE:To enable a stable function to be performed in an air flow rate control system and a blower discharging pressure control system even if a target value of the air flow rate is rapidly changed. CONSTITUTION:The number of revolution of one blower 1 is controlled by a VVVF power supply device 2 and then a combustion air flow rate control device is operated such that an air flow rate supplied to combustion air supplying systems 3a,... of a plurality of facilities is controlled in response to each of target values set in response to a requested amount of combustion air. The combustion air flow rate control device is comprised of a variation sensing part 12 for sensing a variation of the air flow rate target value requested for each of the facilities and an operation output processing part 13 for outputting an operating instruction for limiting to cause the master pressure control over the discharging pressure of the blower 1 to be temporarily held upon detection of the variation of the air flow rate target value with the variation sensing part 12 to the VVVF power supply device 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion air amount control device used for combustion control required for furnace equipment and boiler equipment in the steel industry, for example.

[0002]

2. Description of the Related Art For example, in the steel industry, when supplying combustion air to a plurality of systems of equipment, one blower is controlled in rotation speed by a variable voltage variable frequency (VVVF) power supply device, blower discharge pressure and each system are controlled. Combustion control required for furnace equipment and boiler equipment is performed by controlling the flow rate of combustion air.
In this case, especially when the air flow rate is low, the function is to monitor the air flow rate of each system for the purpose of saving power consumption and change the set value of blower discharge pressure according to the required amount. The rotation speed of the blower is suppressed.

[0003]

However, in such a combustion air flow rate control device, since the air flow rate control and the blower discharge pressure control are continuously controlled respectively, both control will be performed if the target value of the air flow rate changes suddenly. There was a problem that the systems act in a direction to reduce the control deviation, and finally both control systems interfere with each other and become unstable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a combustion air flow rate control device capable of stably operating the air flow rate control system and the blower discharge pressure control system even if the target value of the air flow rate suddenly changes.

[0005]

In order to achieve the above object, the present invention achieves the above object by controlling the rotation speed of one blower by a VVVF power supply device to control the flow rate of the air supplied to the combustion air supply system of a plurality of facilities. In a combustion air flow rate control device that controls based on target values that are respectively set in accordance with required amounts, change detection means that detects changes in the air flow rate target values required for each of the equipment, and air by the change detection means. And a discharge pressure operating means for outputting to the VVVF power supply device an operation command for limiting so that the original pressure control of the discharge pressure of the blower is temporarily held when a change in the target flow rate is detected.

[0006]

In the combustion air flow rate control device having such a configuration, when the change detection means detects a change in the target air flow rate value required for each facility, the discharge pressure operating means causes VV to be applied.
The operation command given to the VF power supply device restricts the source pressure control of the blower discharge pressure to be temporarily held, so that the air flow rate control system and the blower that transiently occur when the air flow rate target value suddenly changes. The discharge pressure control system can be prevented from interfering with each other, and both control systems can function stably.

[0007]

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

FIG. 1 shows a system configuration example of a combustion air flow rate control device according to the present invention. In FIG. 1, 1 is V
A plurality of combustion air supply systems 3a, 3b, ... for supplying combustion air to a furnace facility (not shown) or a boiler with a single blower whose rotation speed is controlled by the VVF power supply device 2.
Are connected. Further, a pressure detector 4 for detecting the blower discharge pressure is provided on the discharge side of the blower 1, and the flow rate detectors 5a, 5b, ... And the flow rate control valves 6a, 6b, ... Are provided in each of the combustion air supply systems 3a, 3b. Are provided respectively.

On the other hand, 7 is a combustion control section for outputting a set value corresponding to the air demand amount from the temperature control of the furnace equipment or boiler equipment of each system as a target signal of each system, 8a, 8
In b, the combustion air flow rate detection signal detected by the flow rate detectors 5a, 5b, ... Of each system and the target signal corresponding to each system input from the combustion control unit 7 are input, and the combustion air flow rate of each system is The flow rate control valve 6a. 6b,
It is a flow rate controller that controls the flow rate by adjusting the opening degree of.

Further, 9 is a set value corresponding to each system output from the combustion control section 7, and is a maximum value selecting section for selecting the maximum value of these setting values. 10 is a maximum value selecting section 9. A polygonal line processing unit 11 which corrects the selected set value based on a polygonal line characteristic given in advance and outputs this as a target signal. Reference numeral 11 denotes the blower 1 detected by the pressure detector 4.
Is a pressure controller to which the discharge pressure detection signal and the target signal output from the broken line processing unit 10 are input.

Further, reference numeral 12 is a target value corresponding to each system output from the combustion control unit 7, and when a sudden change in each target value is detected, a target value for outputting a hold request signal based on a hold request determination process. The change detector, 13 is VV based on the pressure control signal input from the pressure controller 11.
An operation command is given to the VF power supply device 2, and the target value change detection unit 1
When a holding request command is input from 2, the output processing is performed according to the holding request, and an operation command is given to the VVVF power supply device 2 so as to limit the original pressure control of the discharge pressure of the blower 1 to be held. It is an output processing unit. Next, the operation of the combustion air flow rate control device configured as described above will be described.

Now, it is assumed that the set value output from the combustion control unit 7 according to the required air amount of each system is input as target signals to the flow rate controllers 8a, 8b, ... And the maximum value selection unit 9. For example, the flow rate controllers 8a, 8b, ... Compare the air flow rate detection signals detected by the flow rate detectors 5a, 5b, ...
The opening degrees of b, ... Are adjusted so that the combustion air flow rate of each system becomes the target value of that system.

Further, the maximum value selection unit 9 selects the maximum value of the set values corresponding to each system, and the selected set value is given to the polygonal line processing unit 10. In this polygonal line processing unit 10,
Based on the PQ curve determined by the blower performance and the like, the optimum source pressure corresponding to the change in the maximum value of the air flow rate is determined, and this is given to the pressure controller 11 as a setting signal of the discharge pressure of the blower 1. In this pressure controller 11, the discharge pressure detection signal of the blower 1 detected by the pressure detector 4 is compared with the target signal,
It is input to the operation output processing unit 13 which gives an operation command for controlling the discharge pressure of the blower 1 to the source pressure to the VVVF power supply device 2 based on the deviation.

At the same time, the set value corresponding to each system output from the combustion control section 7 is also given to the change detection section 12, and there is no change in the set value at this time, and a hold request is issued to the operation output processing section 13. If not, the operation output processing unit 13
Is VVV based on the deviation input from the pressure controller 11.
An operation command is given to the F power supply device 2, the rotation speed of the blower 1 is controlled, and the discharge pressure thereof is controlled. Further, the change detection unit 12 detects a sudden change in the target value of the air flow rate, and when it is determined that the rate of change has exceeded a certain value, the operation output processing unit 13
A hold request command is issued to. When the operation output processing unit 13 receives the holding request command, the operation output processing unit 13 operates to limit the source pressure control of the discharge pressure of the blower 1 to the VVVF power supply device 2 for a predetermined time from the time when the holding request command is received. Give orders.

After the transient response time of the combustion air flow rate control system of each system and the discharge pressure control system of the blower 1 has elapsed, the hold of the source pressure control of the discharge pressure of the blower 1 is released, and the source pressure control is performed. Returned to.

As described above, in this embodiment, the demand for the combustion air supplied from the blower 1 whose rotation speed is controlled by the VVVF power supply device 2 to the furnace equipment and the boiler equipment through the plurality of combustion air supply systems 3a, 3b ,. The amount of combustion air in each system is controlled by the flow rate controllers 8a, 8b, ... Based on the set value of the combustion control unit 7 set according to the amount, and the maximum value of these set values is set to the maximum value selection unit. 9, the pressure controller 11 calculates the control amount of the discharge pressure of the blower 1 based on the setting signal corrected by the polygonal line processing unit 10, and the change of the air flow rate target value of the combustion control unit 7 is detected by the change detection unit. VV from the operation output processing unit 13 that outputs the control amount of the discharge pressure obtained by the pressure controller 11 when detected by 12 in accordance with the holding request from the change detection unit 12.
The VF power supply device 2 is provided with an operation command for limiting the original pressure control of the discharge pressure of the blower 1 to be temporarily held.

Therefore, even if the target value in the air flow rate control of each system suddenly changes, the unstable elements in both the discharge pressure control system and the air flow rate control system at the time of transient response are eliminated. A stable supply of combustion air is possible even in combustion control of plants such as furnace equipment and boiler equipment, which change easily. Further, by stabilizing the supply of combustion air, efficient and clean combustion can be realized. The present invention is not limited to the embodiments described above and shown in the drawings, and it goes without saying that various modifications can be made without departing from the scope of the invention.

[0018]

As described above, according to the present invention, there is provided a combustion air flow rate control device capable of stably operating the air flow rate control system and the blower discharge pressure control system even if the target value of the air flow rate suddenly changes. Can be provided.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an embodiment of a combustion air flow rate control device according to the present invention.

[Explanation of symbols]

1: Blower, 2: VVVF power supply device, 33, 3b, ...:
Combustion air supply system, 4: Pressure detector, 5a, 5b, ...:
Flow rate detector, 6a, 6b, ...: Flow rate control valve, 7: Fuel control section, 8a, 8b, ...: Flow rate controller, 9: Maximum value selection section, 10: Broken line processing section, 11: Pressure controller, 12 : Change detection unit, 13: Operation output processing unit.

Claims (1)

[Claims] 1. A variable voltage variable frequency (V
VVF) A combustion air flow rate control device for controlling a rotation speed by a power supply device to control an air flow rate supplied to a combustion air supply system of a plurality of equipments based on target values respectively set according to combustion air demands, Change detecting means for detecting a change in the target value of the air flow rate required for each facility, and when the change detecting means detects a change in the target value of the air flow rate, the source pressure control of the discharge pressure of the blower is temporarily held. And a discharge pressure operating means for outputting an operation command to limit the operation to the VVVF power supply device.