JP3844929B2 - Burner number control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to boiler burner number control, and more particularly to a boiler burner number control apparatus suitable for burner ignition / extinguishing adjustment even in an emergency such as load change, system frequency fluctuation, or runback.
[0002]
[Prior art]
FIG. 2 shows a control block for burner number control in the prior art. According to this, the signal B serving as the generator output command in FIG. 2 is also used in principle for burner number control. That is, the adjustment of the number of boiler burners when the load changes is determined in advance in accordance with the generator output command signal by determining the burner pattern and the burner ignition / extinguishing order in advance. A configuration that adjusts the number of burners by detecting and judging whether the load is increasing or decreasing, and outputting a burner ignition command in the upward direction and a burner extinguishing command in the decreasing direction. It was.
[0003]
However, since the generator output command signal also includes a correction signal for the generator output due to frequency fluctuation, a minute load change at the time of frequency fluctuation (generally, about ± 5% of the reference output at that time) If the point fire extinguishing load setting of the burner is overlapped with the frequency fluctuation load, unnecessary burner ignition / extinguishing is performed, so the burner equipment (pulse igniter, (Solenoid valves, limit switches, etc.) are consumed quickly, and particularly for devices used for burner ignition / extinguishing, such as ignition transformers, there is a problem that the lifetime is significantly consumed.
[0004]
For example, the burner equipment will operate when the burner point is extinguished, so the number of operations will be related to the life of the equipment, and in particular, the ignition transformer (burn igniter) etc. This leads to the problem of not getting a good spark.
[0005]
On the other hand, during large frequency fluctuations such as power system accidents, if the burner ignition / extinguishing does not correspond to the change in the actual output of the generator, the relationship between the fuel and the number of burners becomes unbalanced, and the power plant During run-back in the station (load drop operation due to emergency stop of auxiliary equipment), it is necessary to ignite and extinguish the burner according to the load change. In this run-back, the actual output signal of the generator When the burner is ignited and extinguished (during runback, the generator output command G uses the generator actual output MW → switch 15, 1 → A → B in FIG. 2) on the contrary to the load target command As a result, the ignition / extinguishing of the burner was delayed and the burner pressure became unstable.
[0006]
FIG. 2 shows a control block diagram of burner number control in the prior art. In this prior art, as a generator output command signal for adjusting the number of burners, a signal B to which a system frequency control command AFC and a frequency bias signal Δf are added, which is a preceding stage that is switched to an output change command signal at the time of runback. The signal was used.
[0007]
FIG. 3 is a diagram showing the relationship between the burner ignition / extinguishing program in the prior art and the burner ignition / extinguishing with a minute load change. As shown in FIG. 3, the output fluctuation (ΔMW) due to the frequency fluctuation is Because the output is adjusted within a range of ± 5% maximum, the ignition / fire extinguishing command will be output when the ignition / extinguishing program band (Δ'MW) or more is exceeded. Nevertheless, unnecessary burner ignition / extinguishing is performed.
[0008]
Here, the upper part of FIG. 3 shows the characteristics of the function generators 4 and 5, and shows the relationship between the number of fire extinguishing and ignition of the burner with respect to the generator output command, and in the range of Δ′MW. It shows that the number of ignition and extinguishing is changed. The lower diagram of FIG. 3 takes into account the load change (ΔMW) due to frequency fluctuations, and when the Δ′MW <ΔMW, the burnout of the burner is repeated.
[0009]
In addition, runback (works when the load is restricted by the capacity of the auxiliary machine. For example, in the case of 2 units of forced draft fan (FDF) with 100% load, only 50% load will occur when one FDF trips. When the boiler load is quickly reduced to 50% because it is not acceptable, the ignition / fire extinguishing command uses the signal B (see FIG. 2) before the run-back command, so the change in the generator actual output MW signal is used. In other words, the generator actual output MW signal (instead of the target load command shown in FIG. 2) selected by the signal switcher 14 at the time of the runback is not the rapid load narrowing command E at the time of the runback. (The generator actual output MW signal has a delayed response because there is boiler heat storage for rapid narrowing down), and burner ignition / extinguishment command is output, So that the ignition and extinguishing of the burner is delayed with respect to the narrowing of that boiler input.
[0010]
[Problems to be solved by the invention]
The above prior art does not consider reducing the number of times the burner is ignited and extinguished with respect to a minute load change due to frequency fluctuations during load operation (allowable range of burner turndown (stable combustion)). As the frequency of fire extinguishing increases, there is a problem that the consumption rate of burner equipment is large.
[0011]
Also, during large frequency fluctuations such as power system accidents, and during runback in the power plant, burner pressure may become unstable due to delays in ignition and extinguishing of the burner with respect to the load target command.
[0012]
The object of the present invention is to solve the above-mentioned problems of the prior art, and in the burner point fire extinguishing during a load change, it is possible to extend the life of the burner equipment by reducing the number of unnecessary point fire extinguishing accompanying a minute load change. There is to do.
[0013]
Another object of the present invention is to provide a burner number control device capable of quickly igniting and extinguishing a burner according to a load change to a target load in an emergency where a load change must be made rapidly and greatly.
[0014]
[Means for Solving the Problems]
In order to solve the above problems, the present invention mainly adopts the following configuration.
[0015]
A generator output command signal is created using a target load command signal or a generator actual output signal, and a system frequency control command AFC signal and a frequency bias signal due to system frequency deviation, and according to a change in the generator output command signal In the burner number control device that controls the number of ignition and extinguishing of the boiler burner,
During normal operation, among the generator output command signal, a signal obtained by removing the frequency bias signal from the system frequency control instruction AFC signal and the grid frequency deviation, a configuration is used as a command signal number control of the boiler burner .
[0016]
Further, in the burner number control device, wherein the time frequency variation the deviation exceeds a predetermined value of the power system frequency, using the frequency bias signal from the generator actual output signal, the system frequency control instruction AFC signal and the system frequency deviation a generator output command signal generated Te, a configuration is used as a command signal number control of the boiler burner.
[0017]
Further, in the above burner number control device, during the run-back operation by accessory trip, the generator actual output signal, the system frequency control instruction AFC signal and the generator was made using a frequency bias signal according to the system frequency deviation output instead of the command signal, the runback rapid load refine instruction signal set by the runback target load and a target rate of descent is the generator output drops command signal, a configuration is used as a command signal number control of the boiler burner.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
A burner number control apparatus according to an embodiment of the present invention will be described below with reference to FIGS. 1 and 3.
[0019]
The output target value (EDC or DPC) from the central power supply command station (medium pay) is selected by the signal switcher 1 instead of the output command (ALR) set in the power plant, and the change rate limiter 2 The change rate of the input signal is appropriately adjusted and set, and then given as a generator output command C.
[0020]
The generator output command C is switched to the detected generator actual output signal MW by the signal switcher 14 at the time of runback (load lowering operation accompanying an emergency stop of an auxiliary machine such as FDF) or at the time of manual operation of the turbine governor. . Here, when the actual output is determined by the boiler input signal as in the boiler manual mode, the signal switch 15 further switches the generator actual output signal MW to the boiler input signal (BID signal). That is, at the time of runback, MW → switchers 15, 14 → C → D → G is used for the generator output command (as will be described later, E → switcher 13 → switches for burner number control at the time of runback. Use vessel 3 → F).
[0021]
After the system frequency control command AFC signal B and the frequency bias signal A due to system frequency deviation are added to the generator output command C by the adders 8 and 9, the output upper and lower limits are further output by the high / low signal selectors 11 and 12, respectively. Each value is created as a limited signal. Here, the system frequency control command AFC is created in the range of the maximum ± 5% (constant rate) of the generator output command C between 50 to 100% load.
[0022]
Further, the frequency bias signal is determined by the relationship of the governor arbitration rate, and the governor moves according to this value. For example, in the case of a 600 MW power plant with a 60 Hz power system, the governor moves with a relationship of 600 MW / 2.4 Hz with a 4% arbitration rate. Accordingly, the generator output command is also corrected according to the movement of the governor by the frequency bias signal.
[0023]
Next, the burner number control device according to the embodiment of the present invention will be described. According to FIG. 1, the relationship between the generator output and the number of burners is programmed by the function generators 4 and 5 using the signal C in the previous stage to which the system frequency control command B and the frequency bias signal A are added. The output of the upper stage is generated and compared with the actual number of burner ignitions, and the burner ignition or extinguishing is detected by the monitor relays 6 and 7, and the burner number increase command or decrease command is output. To do. In the embodiment of the present invention, the system frequency control command B and the system frequency deviation A of FIG. 1 are not added to the burner number control command F. That is, the generator output command from which B and A are removed is used for the burner number control.
[0024]
Here, the characteristics of the function generators 4 and 5 are such that, as shown in the upper diagram of FIG. 3, the generator output command is input, and the point fire extinguishing operation of the burner is output according to the point fire extinguishing program. As shown in the figure, the number of ignition and extinguishing is changed within the range of Δ′MW.
[0025]
Further, at the time of the runback, the signal switch 13 is switched to the signal E (rapid load narrowing command E at the time of the runback) set by the runback target load and the target descent rate, and the E → switchers 13 and 3 → F are switched. Via, it is used to control the number of burners. Here, the runback works when the load is restricted by the capacity of the auxiliary machine. For example, in the case of two forced draft fans (FDF) at 100% load, one FDF is used. Since only 50% load can be allowed when tripped, it is used to rapidly reduce boiler load to 50%. Note that MW → switchers 15 and 14 → C → D → G in FIG.
[0026]
Furthermore, when a large frequency deviation (deviation exceeding the specified frequency deviation) occurs such as a power system fault, the burner number control command is MW → switch 15 → switch 14 → C → D → switch in FIG. The signal of the device 13 → the switch 3 → F is used.
[0027]
Thus, in the burner number control device according to the embodiment of the present invention, the generator output command C on the upstream side of the system frequency command AFC is used during normal operation, and the command E on the runback side is used in the event of a runback emergency. It is configured to use a signal that takes into account the system frequency control command and its deviation to the actual generator output when there is a large frequency fluctuation.
[0028]
Next, as another embodiment of the present invention, a boiler input acceleration command is generated by using a generator output command signal in order to compensate for a surplus or deficiency of heat storage of the boiler at the time of load change (when the load is increased) This includes overfiring, overpumping, underfiling during underload, and underpumping).
[0029]
In this case, if a boiler input acceleration command that is unnecessary for a minute load change is applied, a disturbance such as steam temperature control occurs, so the circuit configuration is performed by using a signal that removes the load change command component due to frequency fluctuations. The same effect as the embodiment of the invention can be obtained.
[0030]
As described above, the present invention uses the signal C obtained by removing the load fluctuation correction component due to the frequency fluctuation from the generator output command signal D as an index for burner point fire extinguishing control, and when runback occurs. This is achieved by switching from the index signal C to the command signal E after the target runback rate.
[0031]
By using the signal from which the generator output command correction component due to the frequency fluctuation is removed, a fixed generator output signal can be provided even if a minute load change due to the frequency fluctuation occurs. Can be fixed against a minute load change such as when the system frequency fluctuates, and unnecessary fire extinguishing of the burner is eliminated. As a result, the life of the burner device can be extended.
[0032]
Furthermore, since a load change requiring an emergency is switched to a signal corresponding to the load change, quick burner ignition / extinguishing corresponding to the load change is possible, and the burner pressure is also stabilized.
[0033]
【The invention's effect】
According to the present invention, even if a minute load change due to the frequency fluctuation occurs by using the signal from which the generator output command correction component due to the frequency fluctuation is removed, it is unnecessary for such a minute load change. This eliminates the point-extinguishing of burners and extends the life of burner equipment.
[0034]
Furthermore, in response to an emergency load change, it is possible to switch to a signal corresponding to the load change, enabling quick burner ignition / extinguishment corresponding to the load change, stable burner pressure, and stable fuel adjustment. It becomes.
[Brief description of the drawings]
FIG. 1 is a diagram showing a control block of burner number control according to an embodiment of the present invention.
FIG. 2 is a diagram showing a control block of burner number control in the prior art.
FIG. 3 is a diagram showing a relationship between a burner ignition / digestion program and burner ignition / extinguishing with a small load change in the prior art.
[Explanation of symbols]
1, 3, 13, 14, 15 Switch 2 Change rate limiter 4, 5 Function generator 6, 7 Monitor relay 8, 9 Adder 11 High signal selector 12 Low signal selector

Claims (3)

A generator output command signal is created using a target load command signal or a generator actual output signal, and a system frequency control command AFC signal and a frequency bias signal due to system frequency deviation, and according to a change in the generator output command signal In the burner number control device that controls the number of ignition and extinguishing of the boiler burner,
During normal operation, among the generator output command signal, characterized in that a signal obtained by removing the frequency bias signal from the system frequency control instruction AFC signal and the grid frequency deviation, is used as the command signal number control of the boiler burner Burner number control device. In claim 1,
Wherein the time frequency variation the deviation exceeds a predetermined value of the grid frequency, the generator actual output signal, a generator output command signal generated by using the frequency bias signal from the system frequency control instruction AFC signal and the system frequency deviation burner number control device, which comprises using as a command signal number control of the boiler burner. In claim 1,
During the run-back operation by accessory trip, the generator actual output signal, instead of the power generator output command signal generated by using the frequency bias signal from the system frequency control instruction AFC signal and the grid frequency deviation, the power generator output the runback rapid load refine instruction signal set by the runback target load and a target rate of descent is drop command signal, the burner number control device, which comprises using as a command signal number control of the boiler burner.

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