JP2002243102A - Reheater gas damper opening degree controller utilizing change of superheater spray flow rate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the improvement of controllability of a reheater vapor temperature through a simple constitution employing an already existing signal without providing any pressure gauge and a multitude of thermometers. SOLUTION: The reheater gas damper opening degree controller is provided with a damper opening degree correction operating circuit 45 equipped with a subtractor 49 for obtaining a spray flow rat difference signal 60 by subtracting a reference spray flow rate 47 obtained by converting a reference signal 27 by a first function generator 46 from a superheater total spray flow rate signal 48, a second function generator 54 for obtaining a flow rate difference signal 55 after correcting a neutral zone by converting the spray flow rate difference signal 50 from the subtractor 49, an integrator 56 for obtaining an opening degree correcting signal 57 by integrating the spray flow rate difference signal 55 after correcting the neutral zone, and an adder 58 for adding the opening degree correcting signal 57 to the reheater gas damper reference opening degree program 29 of an automatic plant controller 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reheater gas damper opening control device utilizing a change in a superheater spray flow rate.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a boiler. In FIG. 4, reference numeral 1 denotes a boiler main body having a furnace 1a and a rear heat transfer section 1b, and 2 denotes a fuel into the furnace 1a of the boiler main body 1. Burner to inject and burn, 3 is primary superheater, 4 is secondary superheater, 5 is tertiary superheater, 6 is final superheater, 7 is primary reheater, 8 is secondary reheater, 9 is node It is a charcoal unit, and generates fuel gas by injecting fuel from the burner 2 into the furnace 1a of the boiler main body 1 to burn the fuel gas, circulate the generated combustion gas, and make the secondary superheater 4, the tertiary superheater 5, heat exchange with the final superheater 6, the secondary reheater 8, the primary superheater 3, the primary reheater 7, and the economizer 9, and the exhaust gas after the heat exchange is discharged to the exhaust gas duct 10, and the downstream side After removing nitrogen oxides and sulfur oxides with a flue gas treatment device (not shown) such as denitrification and desulfurization installed in It is adapted to release to.

On the other hand, FIG. 5 shows a water supply / steam system of the above-mentioned boiler. The boiler water is supplied to an evaporator 1 formed on a furnace wall of a furnace 1a of a boiler body 1 in which fuel is burned.
1, the steam is separated into water and steam by the steam separator 13 through the nose portion 12, and the steam separated from the water by the steam separator 13 is supplied to the ceiling of the boiler main body 1 and the peripheral wall 1 of the rear heat transfer section.
4, is superheated by the primary superheater 3, the secondary superheater 4, the tertiary superheater 5, and the final superheater 6, is guided to the high-pressure turbine 15, and drives the high-pressure turbine 15 to generate power. The steam after driving the high-pressure turbine 15 is guided to the primary reheater 7 and the secondary reheater 8, and is reheated by the primary reheater 7 and the secondary reheater 8. Low pressure turbine 16
And the medium / low pressure turbine 16 is driven to generate power. The steam after driving the medium / low pressure turbine 16 is led to a condenser 17 and returned to the boiler feedwater. The boiler feedwater is condensed by a condensate desalination device 18 and a low pressure feedwater heater 19.
And the deaerator 20, and the water is fed to the economizer 9 by a feedwater pump 21 via a high-pressure feedwater heater 22.
And is fed to the evaporator 11 and circulated.

[0004] In FIG. 4, reference numeral 23 denotes a rear heat transfer section 1.
b, which is provided below the economizer 9 on the primary reheater 7 side and the primary superheater 3 side to control the flow rate of the combustion gas on the primary reheater 7 side and the primary superheater 3 side. The reheater gas damper 23 controls the flow rate of gas passing through the primary reheater 7 according to a damper opening command 25 from a reheater gas damper opening control device 24, thereby producing reheat steam. The temperature is controlled.

FIG. 6 shows a conventional reheater gas damper opening control.
FIG. 3 shows an example of the device 24, in which the reheater gas
The opening control device 24 has an automatic plant control device 26.
ing. The automatic plant control device 26 has a MWD (Mega
Demand or BID (Boiler Input Dima)
From the reference signal 27 which is the reference for boiler control such as
Reheater gas damper basic opening degree program by number generator 28
I have a ram 29. This function generator 28 is shown in FIG.
As shown in FIG. _Three(X)
Exit the reheater gas damper basic opening program 29
It is designed to help.

The adder 30 adds a reheater gas damper advance correction signal 31 to the reheater gas damper basic opening degree program 29. This reheater gas damper advance correction signal 31 is used to correct the delay in the rise of the steam temperature at the outlet of the reheater (secondary reheater 8) when the load rises, as shown in FIG.
Is added, as shown in FIG.
In order to compensate for a delay in dropping the reheater outlet steam temperature when the load is reduced, a leading decrease signal 31b as shown in FIG. 9 is added. Further, the reheater gas damper advance correction signal 31
Is added to the reheater gas damper basic opening program 29
, A correction signal 34 from a proportional integrator 33 to which the reheater outlet steam temperature deviation 32 is input is added by an adder 35. The reheater outlet steam temperature deviation 32 is the difference between the temperature detected by the thermometer 36 in FIG. 5 which detects the reheater (secondary reheater 8) outlet steam temperature and the reference value of the temperature,
The proportional integrator 33 outputs the correction signal 34 to the adder 35 so as to eliminate the reheater outlet steam temperature deviation 32 by inputting the reheater outlet steam temperature deviation 32.

[0007] In the case of a coal-fired boiler, it is known that the type of coal used as fuel changes the heat collection of the furnace 1a. For example, when the coal burns afterwards, the heat collection on the rear heat transfer section 1b side increases and the heat collection on the furnace 1a side decreases. Also, when ash generated during the combustion adheres to the inner wall of the furnace wall of the furnace 1a, the heat transfer of the furnace 1a decreases, and the heat collection on the furnace 1a side also decreases. It is also known that, as described above, when the heat collection of the furnace 1a changes, the opening of the reheater gas damper 23 changes so as to increase or decrease from the reference value.

As described above, when the heat collection of the furnace 1a changes, the correction signal 34 from the proportional integrator 33 based on the reheater outlet steam temperature deviation 32 as described above, and the reheater gas damper basic opening degree. Only by correcting the program 29, a control delay occurs due to the time constant, so that the reheater outlet steam temperature cannot be stably controlled. That is,
Even if the opening degree of the reheater gas damper 23 is changed, the change in the opening degree does not immediately change in the reheater outlet steam temperature. Had become stable.

In order to eliminate such control instability,
It has been proposed to provide a damper opening correction device 37 shown in FIG. This damper opening correction device 37 uses a multi-carbon type control device 37A (CAPS).

In order to use the multi-coal type control device 37A, as shown in FIG.
8 and a thermometer 39, and a thermometer 39 at the inlet of the evaporator 11 and at the outlet of the nose portion 12. Further, when the sprayer 40 is provided at the inlet of the primary superheater 3 and at the outlet of the primary superheater 3, before and after the spray 40, and when the sprayer 41 is provided at the outlet of the secondary superheater 4, If a spray 42 is provided before and after the spray 41 and at the outlet of the tertiary superheater 5, thermometers 39 are provided before and after the spray 42 and at the outlet of the final superheater 6.

The detected pressure from the pressure gauge 38 and the temperature detected by each of the thermometers 39, 39,... Are input to a multi-coal type controller 37A having a large arithmetic capacity, so that each of the boilers can be controlled. The heat collection of the furnace 1a is obtained by calculating the heat collection in the heat transfer section, and the opening correction signal 4 of the reheater gas damper based on the change of the heat collection of the furnace 1a.
3 is calculated and output.

The opening correction signal 43 from the multi-coal type controller 37A is added to the reheater gas damper basic opening program 29 of the automatic plant controller 26 by an adder 44.

The damper opening correction device 37 shown in FIG.
Then, the heat recovery of the furnace 1a is obtained by the multi-coal type control device 37A, and the opening correction signal 43 obtained according to the change of the heat recovery of the furnace 1a is input to the automatic plant control device 26, and the reheater gas damper Since the opening of the reheater gas damper 23 is controlled by the damper opening command 25 in consideration of the change in the heat absorption of the furnace 1a, the heat collection of the furnace 1a is controlled as described above. Even if it changes, stable control can be performed so that the reheater outlet steam temperature becomes equal to the reference value.

[0014]

However, since the damper opening correction device 37 is controlled by using the multi-carbon type control device 37A, the pressure gauge 38 and the plurality of thermometers 39, 39 are used. .. Require a large-capacity computing device for computing the heat collection of the furnace 1a from the temperature detected by the...

A pressure gauge 38 and a plurality of thermometers 39, 39
… Needs to be installed, which leads to an increase in equipment costs. When applied to an existing boiler, a pressure gauge 3
. And a large number of thermometers 39, 39...

The present invention has been made in view of the above circumstances, and has made it possible to improve the controllability of the reheat steam temperature with a simple configuration using existing signals without providing a pressure gauge and a large number of thermometers. An object of the present invention is to provide a reheater gas damper opening control device using a change in a superheater spray flow rate.

[0017]

SUMMARY OF THE INVENTION The present invention relates to an automatic plant control device for outputting a damper opening command to a reheater gas damper based on a reheater gas damper basic opening program obtained from a reference signal, and a reference signal. Is subtracted from the reference spray flow rate determined by converting the first function generator by the first function generator and the total spray flow rate signal of the superheater that has detected the spray flow rate, to obtain a spray flow rate deviation signal. And a second function generator for converting the spray flow deviation signal of the above to obtain a spray flow deviation signal after dead zone correction, and integrating the dead zone corrected spray flow deviation signal from the second function generator to obtain an opening correction signal. A damper opening correction arithmetic circuit having an integrator to be obtained and an adder for adding an opening correction signal from the integrator to a reheater gas damper basic opening program of the automatic plant control device. Reheater utilizing change of superheater spray flow rate and gas damper opening control device, which relates to.

In the above means, the damper opening correction operation circuit may include a switch between the subtractor and the integrator for outputting a 0% signal during a load change.

According to the above means, the following effects can be obtained.

During operation of the boiler body, the superheater total spray flow signal, which detects the spray flow of the superheater, and the MWD
Alternatively, the reference flow signal of the BID is input to the first function generator, and the reference spray flow rate obtained by conversion is input to the subtractor and subtracted to obtain a spray flow rate deviation signal. The spray flow deviation signal from the subtractor is input to a second function generator via a switch to be converted into a dead band corrected spray flow deviation signal, and the obtained dead band corrected spray flow deviation signal is integrated by an integrator. Is integrated to obtain an opening correction signal. The opening correction signal from the integrator is added to the reheater gas damper basic opening program of the automatic plant controller via an adder, whereby the reheater gas damper basic opening program changes the superheater spray flow rate. That is, it is corrected to a state in which the heat collection of the furnace is considered.

Therefore, the damper opening command output from the automatic plant control device to the reheater gas damper takes into account the change in the superheater spray flow rate, that is, the change in the heat recovery of the furnace. Fluctuations in the outlet steam temperature are minimized, and stable control can be performed.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a reheater gas damper opening control device according to the present invention. In the drawing, the same reference numerals as in FIG. 6 denote the same parts, and a detailed description will be given. Are omitted, and only the features of the present invention will be described in detail below.

The inventor of the present invention has found that when the heat collection of the furnace changes and the heat collection of the furnace decreases (increases), the heat collection on the superheater side increases (decreases), so that the superheater spray flow rate becomes lower than the reference value. Focusing on the tendency to increase (decrease), the damper opening correction that corrects the reheater gas damper basic opening program of the automatic plant control device with the opening correction signal calculated based on the change in the total spray flow of the superheater An arithmetic circuit was provided.

In FIG. 1, a damper opening correction arithmetic circuit 4
Reference numeral 5 indicates a reference spray flow rate 47 by inputting and converting a reference signal 27 composed of MWD or BID into a first function generator 46. This first function generator 46
As shown in FIG. 2, a reference spray flow rate 47 obtained from static characteristics such as a function F ₁ (x) is output in response to the input of the reference signal 27.

The reference spray flow rate 47 and the superheater total spray flow rate signal 48 are input to a subtractor 49 and subtracted to obtain a spray flow rate deviation signal 50. At this time, since the conventional automatic plant controller 26 also detects the superheater spray flow rate, the superheater total spray flow signal 48 obtained thereby is input to the subtracter 49 and used.

The spray flow deviation signal 50 from the subtracter 49 is input to a switch 51. The switch 51 switches so that the spray flow deviation signal 50 is cut off and the 0% signal 53 is output when the load change 52 signal is input when the load changes.

The spray flow deviation signal 50 from the switch 51 is converted into a spray flow deviation signal 55 after dead zone correction by being input to a second function generator 54. As shown in FIG. 3, the second function generator 54 supplies the spray flow deviation signal 50 with a required dead band and gain, such as a function F ₂ (x), in response to the input of the spray flow deviation signal 50. A signal 55 is output. 3, the proportional integrator 33 of the automatic plant controller 26 has a dead band of a predetermined width so that the minute control is not repeated. The dead zone corrected spray flow rate deviation signal 55 obtained by the second function generator 54 is integrated by an integrator 56 to become an opening correction signal 57.

The opening correction signal 57 obtained by the integrator 56 is added to the reheater gas damper basic opening program 29 of the automatic plant control device 26 via an adder 58. .

Next, the operation of the illustrated example will be described.

When the boiler body 1 is operated, a superheater total spray flow signal 48 which detects the spray flow rate of the superheater (for example, the spray flow rates of the sprays 40, 41 and 42 in FIG. 5) is input to a subtractor 49. At the same time, the MWD or BID reference signal 27 is input to the first function generator 46 and converted and the reference spray flow rate 47 obtained and input to the subtractor 49 to be subtracted to obtain the spray flow deviation signal 50. obtain.

The spray flow deviation signal 50 from the subtractor 49
Is input to the second function generator 54 via the switch 51 and is converted into the dead zone corrected spray flow deviation signal 55. The dead zone corrected spray flow deviation signal 55 obtained by the second function generator 54 is An opening correction signal 57 is obtained by being integrated by the integrator 56. The opening correction signal 57 from the integrator 56 is added to the reheater gas damper basic opening program 29 of the automatic plant control device 26 via the adder 58, whereby the reheater gas damper basic opening program 29 Is corrected to a state in which the change in the superheater spray flow rate, that is, the heat collection of the furnace 1a is taken into consideration.

Accordingly, the opening correction signal 57 is supplied to the adder 5
The reheater gas damper advance correction signal 31 is added to the reheater gas damper basic opening degree program 29 added at 8 through the adder 30, and the reheater outlet steam temperature deviation 32 is further added through the adder 35. Automatic plant controller 26 which adds the correction signal 34 obtained by the proportional integrator 33 from
Since the change in the superheater spray flow rate, that is, the heat collection of the furnace 1a is taken into consideration, the damper opening degree command 25 of the above (2) minimizes the fluctuation of the reheater outlet steam temperature and can perform stable control. Become like

The reheater gas damper opening control device utilizing the change in the superheater spray flow rate according to the present invention is not limited to the above-described example, but may be used within the scope of the present invention. Of course, various changes can be made.

[0035]

As described above, according to the reheater gas damper opening control device utilizing the change of the superheater spray flow rate of the present invention, the change of the heat collection of the furnace is controlled by the change of the spray flow rate of the superheater. The reheater gas damper basic opening program is corrected by the opening correction signal corresponding to the change in the heat absorption of the furnace. Compared to the above, an excellent effect that it is possible to provide an inexpensive device by drastically reducing the device configuration and computational capacity and to perform stable control while minimizing fluctuations in the reheater outlet steam temperature. Can be played.

[Brief description of the drawings]

FIG. 1 is a control block diagram illustrating an example of an embodiment of the present invention.

FIG. 2 is a diagram showing a function input to a first function generator shown in FIG. 1;

FIG. 3 is a diagram showing a function input to a second function generator shown in FIG. 1;

FIG. 4 is an overall schematic configuration diagram illustrating an example of a general boiler.

FIG. 5 is a schematic configuration diagram showing a water supply / steam system of the boiler shown in FIG.

FIG. 6 is a control block diagram showing an example of a conventional reheater gas damper opening control device.

FIG. 7 is a diagram showing a function input to the function generator shown in FIG. 6;

FIG. 8 is a diagram when the reheater gas damper advance correction signal of FIG. 7 is an advance increase signal.

FIG. 9 is a diagram illustrating a case where the reheater gas damper advance correction signal of FIG. 7 is an advance decrease signal.

[Explanation of symbols]

 23 Reheater gas damper 25 Damper opening command 26 Automatic plant controller 27 Reference signal 29 Reheater gas damper basic opening program 45 Damper opening correction operation circuit 46 First function generator 47 Reference spray flow rate 48 Superheater total spray Flow signal 49 Subtractor 50 Spray flow deviation signal 51 Switch 52 During load change 5 30% signal 54 Second function generator 55 Spray flow deviation signal after dead zone correction 56 Integrator 57 Opening correction signal 58 Adder

Claims (2)

[Claims] An automatic plant control device for outputting a damper opening command to a reheater gas damper based on a reheater gas damper basic opening program obtained from a reference signal, and a reference signal generated by a first function generator. A subtractor that obtains a spray flow deviation signal by subtracting the reference spray flow rate obtained by the conversion and the superheater total spray flow signal that has detected the spray flow rate, and converts the spray flow deviation signal from the subtractor A second function generator for obtaining a spray flow rate deviation signal after dead zone correction, an integrator for integrating the dead zone corrected spray flow rate deviation signal from the second function generator to obtain an opening correction signal, An adder for adding an opening correction signal from the automatic plant controller to the reheater gas damper basic opening program of the automatic plant control device. Reheater gas damper opening control device using a change. 2. The superheater spray flow rate as claimed in claim 1, wherein the damper opening correction operation circuit includes a switch between the subtractor and the integrator, which outputs a 0% signal during a load change. Reheater gas damper opening control device using change.