JPS63194120A - Fuel control system for coal feeder - Google Patents

Abstract

PURPOSE:To stabilize a fuel line by controlling to stabilize combustion of a boiler, by previously controlling the coal rate by a corrected mill differential pressure in accordance with the changing rate of required value of coal feed rate, and by controlling the feeding rate of coal by adding a primary delay function to an operating signal to a coal feeder. CONSTITUTION:A preceding circuit 'H' is a driver to bring the rising of mill differential pressure in a mill near to a primary air differential pressure by previously controlling the differential pressure by adding a corrected value of mill ratio to it. A coal- feeder operating signal 31 calculated by a feeding coal arithmetic and adding circuit E-1 adds a primary delay circuit 'I' to a coal feeding rate command, that is a demanded value to the primary air differential pressure command for a primary air damper. Then the coal feeder is operated by a feed coal command. The delay time which appears as a mill differential pressure, that is, a delay time to pulverize coal is corrected by the primary delay circuit 'I'. A corrected value is added to the set signal of coal feeding rate, and a proper control is performed by a control circuit G-1 constituted of a proportional control and an integral control. The change caused by stoking of coal fuel is absorbed by the primary delay circuit 'I', and a feed coal controlling signal 28 which conducts a stabilized coal feeding can be output.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention is aimed at stabilizing a fuel control system in combination with equipment with a first-order lag time constant of equipment in a coal-fired power plant, in the fuel control of a coal-fired power plant. This invention relates to a coal supply fuel control device.

(Prior art) In the conventional fuel control method, the coal supply amount command and the primary air command are controlled by proportional control, integral control,
Since the control was a combination of differential control, the response of the amount of coal to the amount of -water and air has a time constant, which causes a large delay in the control system. A deviation occurs in the amount of air relative to the primary air amount command, resulting in an imbalance in fuel control, which causes the problem that pulverized coal, which is the fuel, cannot be stably supplied from the mill to the boiler, which is the combustion device.

FIG. 2 shows an example of the configuration of a conventional fuel control device for a coal-fired power plant. Turbine 1, which is a load, has pressure.

It requires steam at a constant temperature, and the rotation of the turbine 1 drives the generator 2 to generate electric power. In the boiler 3 as well, steam, temperature, and pressure must be kept constant. In order for the boiler 3 to always create steam conditions with constant pressure and temperature and to control the amount of steam through the steam pipe and the steam control valve 4, it is necessary to maintain the weight balance and energy balance of the water in the boiler 3. must be preserved.

In order to maintain the weight balance and energy balance of the water in the boiler 3, the steam flow rate, pressure, and temperature of the boiler output are detected by detectors 5 and 6.7, respectively, and the signals from the respective detectors and the boiler The output steam flow rate signal a, pressure signal 10, and temperature signal 11 are input to the boiler fuel control device 8. Based on the detected boiler output signal quantities 9 and 10.11, the boiler fuel control device 8 sends the steam from the turbine 1 through the condenser 12 to the feed water pump 13 to control the feed water control valve 14 using the feed water control signal 15. to control the amount of water supplied to the boiler 3, and control the vane operating device 16 using a vane opening control signal 17 from the boiler fuel control device 8 to control the opening and closing of the vanes 18. By controlling the opening of the vanes 18, the flow rate of the air 20 sent through the primary air fan 19 is controlled, and the air 20 is supplied to the input side of the mill 21. This maintains the weight balance of the water in the boiler 3 and also maintains the energy balance. The air flow rate in the mill 21 and the supply of pulverized coal to the boiler 3 are controlled as follows.

Coal 24 from the hopper 22 is sent to the mill 21 by a coal feeder 23, where it is crushed. The crushed pulverized coal 25 is supplied to the boiler 3 by air 20 controlled by a primary air fan 19 and combusted.

The amount of coal supplied to the boiler 3 is controlled by detecting the difference between the inlet air pressure and the output air pressure of the mill 21 using a mill differential pressure detector 26, and transmitting a mill differential pressure signal 27 using the mill differential pressure to the boiler fuel control device. 8 and outputs a coal supply amount adjustment signal 28.

Further, the air flow rate signal 30 detected by the air amount detector 29 of the air 20 is inputted to the boiler fuel control device 8, and the air flow rate signal 30 is multiplied by a certain ratio inside the boiler fuel control device [8]. The coal feeder operation signal 31 is output based on the deviation from the set value, and the coal feeder operating device 32 is operated to control the coal feeder 23 and control the coal feed amount. or,
Based on the signal of the load control command 34 from the central power supply station 33, it is input to the boiler fuel control device 8, and the coal feeder operating device 32 is controlled by the coal feeder operation signal 31 according to the state quantity of the plant.

Next, the operation of the conventional fuel control system shown in FIG. 3 will be explained. The difference between the inlet air pressure and the outlet air pressure of the mill 21 is detected by the mill differential pressure detector 26, and the mill differential pressure signal 27 of the mill differential pressure detector and the air flow rate signal 30 are determined based on the inlet air flow rate and the outlet air flow rate. This is a plant state quantity that indicates the ratio of flow rates. A steam flow rate signal 9, a pressure signal 10, and a temperature signal 11 of the boiler output are input to a conversion calculation circuit A, and then input to a calculation circuit C through a first-order lag function circuit B. -The second lag function circuit B is provided to correct the transmission delay of pulverized coal from the mill to the boiler. The mill differential pressure signal 27 is input to the calculation circuit C. By calculating the ratio between the control value of the transmission delay amount of pulverized coal and the mill differential pressure signal amount in the calculation circuit C, a parameter value indicating the particle size of the pulverized coal to be supplied to the mill 21 is output, and the coal A coal supply amount signal that takes into account the grain size of the coal is input to the coal supply calculation and addition circuit E.

On the other hand, the mill differential pressure signal 27 is input to the adjustment circuit to correct the mill ratio, and is input to the coal supply calculation and addition circuit E, which outputs the coal feeder operation signal 31.

Further, the air flow rate signal 30 is input to the ratio calculation circuit F.

A coal supply amount setting signal is outputted by multiplying by a certain ratio, and is inputted to the adjustment circuit G to adjust the coal supply amount to the hopper 22 1, and a coal supply amount adjustment signal 28 is output.

(Problems for Solving the Invention) In this configuration, if the quality of the coal 24 supplied to the mill 21 is constant and the particle size of the pulverized coal 25 pulverized by the mill 21 is constant, the mill differential pressure can provide accurate However, if the quality of the coal varies or is low, it is impossible to accurately measure the coal supply amount due to errors in the mill differential pressure, and the boiler The fuel control device 18 becomes unstable in combustion due to an imbalance between the amount of air and the amount of coal, and cannot perform constant boiler combustion control.

Further, the operation of the coal feeder operating device 32 in response to the coal feeder operation signal 31 and the vane opening control signal 17 that controls the air amount of the primary air fan that takes in the air 20 are sent to the vane operating device 16 to control the amount of coal. The response delay was large, causing an imbalance between the amount of coal and air inside the mill 21, and the boiler 3
There is a problem in that the pulverized coal 25 cannot be stably supplied.

[Structure of the invention]

(Means for Solving the Problems) The present invention corrects the mill differential pressure based on the ratio of the mill differential pressure to the boiler output in the control circuit of the coal feeder system, and uses the corrected mill differential pressure to feed the coal feeder. The amount of coal is controlled in advance in accordance with the rate of change of the required value of coal, and the amount of coal supplied is controlled by adding a first-order lag function to the coal feeder operation signal in order to control the amount of coal supplied to the hopper. This is how it was done.

(Function) As a result, in the combustion control system of the boiler, the fuel system that performs stable combustion control of the boiler can be stabilized.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1 shows an embodiment of the boiler fuel control device of the present invention. The difference from FIG. 3 is that the adjustment circuit D-L controls the proportional control and the integral FrJ, the preceding circuit H1, the coal supply calculation addition circuit E- 1. An addition circuit J that adds a signal obtained by passing the first-order lag function circuit I and the air flow rate signal 30 through the ratio calculation circuit F to the coal supply amount adjustment signal 28, and the addition circuit J. A mill differential pressure signal 27 obtained by providing an adjustment circuit G-1 which adds proportional control and integral control to the output of is added to the coal supply calculation addition circuit E-1 through the preceding circuit H.

The air flow rate signal 30 is multiplied by a constant ratio from the ratio calculation circuit F to output a coal supply amount setting signal, which is input to the coal supply calculation addition circuit E-1. The advance circuit H brings the rise of the mill differential pressure within the mill closer to the primary air differential pressure by adding advance control to the mill ratio correction value. Further, the coal feeder operation signal 31 calculated from the coal supply calculation adding circuit E-1 adds a primary delay circuit to the coal supply amount command of the request value for the primary air differential pressure command of the primary air differential pressure bar. , the delay time when the coal feeder operates according to the coal feed command and the mill differential pressure occurs, that is, the pulverization delay time from coal to pulverized coal, is 1.
Adjustment circuit G-1 composed of proportional control and integral control, corrected by the next delay circuit I and added to the setting signal of 1 coal supply amount
This outputs a coal supply adjustment signal that performs appropriate control and absorbs fluctuations in coal input using the first-order lag circuit to provide a stable coal supply.

〔Effect of the invention〕

According to the present invention, a preceding circuit is added to the feeder operation signal,
By using proportional control and integral control in the regulation circuit, the responsiveness to fluctuations in the mill differential pressure signal has been improved.Furthermore, by adding an air flow rate commensurate with the coal supply by coal feeder operation, the coal Balance control of air volume and air flow rate can be performed, and stable boiler combustion control can be performed.

Furthermore, by adding a first-order delay function circuit for coal pulverization (1) and (2), it is possible to perform mill ratio control in which the mill ratio signal is stable and the coal supply adjustment signal is continuously stable.

The coal supply adjustment signal enables stable coal supply control even when load changes.

The present invention can be configured not only by an analog circuit, but also by a configuration using digital control to perform boiler combustion control and coal supply control, and a stable control system can be configured.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a boiler fuel control device of the present invention, FIG. 2 is a block diagram of a fuel control device for a coal-fired power plant, and FIG. 3 is a block diagram of a conventional fuel control device. 1... Turbine 21... Mill 2
... Generator 22 ... Hopper 3
... Boiler 23 ... Coal feeder 4
...Steam control valve 24...Coal 5.
...Steam flow rate detector 25...Pulverized coal 6.
...Pressure detector 26...Mil differential pressure detector 7...Temperature detector 27...Mil differential pressure signal 8...Boiler fuel control device 28.
... Coal supply amount adjustment signal 9 ... Steam flow rate signal of boiler output 29 ... Air amount detector IO ... Pressure signal of boiler output 30 ... Air flow rate signal 11 ... Temperature signal of boiler output 31...Coal feeder operation signal 16
... Vane operating device 32 ... Coal feeder operating device 17 ... Vane opening control signal 18 ... Vane 19 ... -Next air fan A ... Conversion calculation circuit meter ... First-order delay Function circuit C...Arithmetic circuit D...Adjustment circuit E...Coal supply calculation addition circuit F...Ratio calculation circuit G...Adjustment circuit H...Advance circuit J...Addition circuit ■・...1st-order lag function circuit agent Patent attorney Nori Chika Ken Yutong Wang Hou Hongbun Ho ゛4 Laeka r, Kai 3 n Fig. 1 Fig. 2

Claims (2)

[Claims] (1) A mill that inputs the coal supplied by controlling the hopper from the coal feeder and the air amount controlled by the vane of the primary air fan, and sends out the pulverized coal that has been pulverized by the mill and burns it. In order to improve the response delay of coal mills in the boiler, the turbine that is driven by the amount of steam produced by the combustion of the boiler, and the boiler combustion control system that supplies water to the boiler through the steam from the turbine through the condenser and feed pump. A mill differential pressure signal of the air pressure ratio between the inlet and outlet of the mill and a preceding circuit are added to the mill differential pressure signal, and the boiler output and primary air flow rate are coordinated through the primary lag circuit that corrects the transmission delay of the boiler output. A coal supply fuel control device characterized by controlling the coal feeder in an optimal manner. (2) In claim 1, a primary delay circuit is added to the coal feeder operation signal to which the preceding circuit is added, thereby correcting the response delay of coal crushing and coordinating the air flow rate and the mill differential pressure. A coal supply fuel control device characterized by performing optimal coal supply adjustment control for advance control of a coal mill.