JPS5895118A - Method for controlling steam temperature - Google Patents

Abstract

PURPOSE:To prevent fluctuations in main steam temperature when the output varies by a method wherein an output precedence bias signal is applied before the commanded value for fuel supply changes and the bias signal is reset when the commanded value commences to change. CONSTITUTION:A steam temperature output precedence bias setting console 17 is arranged to apply precedently a bias signal DBIAS on the day when fuel supply quantity indication is made before the output changes thereby compensating delays in response to stoker and mill. An electronic computer 18 calculates the precedence bias signal and inputs it to the bias setting console 17. By applying the precedence bias DBIAS to the negative side when the output is dropping and applying it to the positive side when the output drop has completed, the defference between the fuel supply value commanded by a control system for the whole plant and an actual quantity of fuel supplied due to delays in response to coal stokers and mills can be compensated. By this arrangement, it is possible to prevent fluctuations in main steam temperature when the output varies.

Description

DETAILED DESCRIPTION OF THE INVENTION 1ml Field of the Invention The present invention provides a method for controlling steam temperature in a coal-fired power plant 5:
related.

lbl Technical Problem 81 Figure is a system A configuration diagram showing the overall configuration of coal-fired power loading. Water supply flow 111i' supplied from water supply pump 11
The WF is sent to the vessel 2I, where it is heated by a coal burner 3 and becomes steam. Steam from the boiler 2 passes through a steam pipe 4' and is sent to a turbine 6 while its flow k is regulated by a control valve 5. The turbine 61 is directly connected to the generator 7, and is designed to generate electric power.

A plant integrated control device 8 is a device that controls such a steam system. This is to control the input m (fuel amount, feed water flow rate) to the boiler 2 and the output amount (steam pressure and steam temperature) of the boiler 2 while coordinating the boiler 2 and the turbine 6.

That is, the generated power Mj of the generator 7, the water supply flow rate IWν, the steam pressure P, and the steam temperature τ are fed back, and the load request amount (target value of generated power amount) 8;
i! Driving device for water pump l 419. Control valve 5, coal feeder 10. A command is issued to each mill 11 that crushes coal into fine powder.

Coal feed $110 and mill 11 are each installed in multiple locations, and 1% of each coal burner 3 is #1 category (vertical mold powder)! supply In coal-fired power plants, coal is treated as fuel for boiler 2 in this way, so the total fuel ν in the power plant is A block diagram of the fuel control system during coal-only combustion by the plant integrated control system @gC is shown in the IJZ diagram.

The output requirements for the power plants are determined by commands from the central dispatch center based on the general operation of the power system and **. In response to the change 62 in the output demand, the power plant increases or decreases the output at a constant rate. This operation is performed by giving the boiler 2 a fuel input amount corresponding to the output change by the plant integrated control WaS. That is, the target value 1 of the generated power; the target value of the corresponding fuel amount and the fuel amount DV corresponding to the actual amount of generated power.
The deviation ΔDv from On the other hand, the differential calculation element 12B calculates the rate of change in the target value of the amount of fuel that changes in response to the change in the target value of the amount of generated electric power.
Fuel command for O - two ahead? This is to give the T-value molecule v.

Here, for the fuel command p' to the coal feeder, coal feed am
Since the speed delay Tatami &: 13 works, the power supply ajiIiv is obtained as "'&! Therefore, by passing the feeder speed vy conversion element 16, the fuel amount Dv'I
k is returning. In this way, the amount of fuel is adjusted to obtain the desired generated power.

However, the plant integrated control system fIL as described above
In the fuel flow rate control system according to No. 8, there is a difference between the amount of fuel DV obtained as the actual input fuel signal and the amount of fuel actually supplied to the coal burner C2 and burned.

This is as shown in Figure 2. This is because the fuel supplied by the degree V is supplied to the coal burner and burned with the addition of the coal feeding slow velocity dead time element 14° and the mill dead time element 15. Therefore, the third factor is As shown, the actual combustion amount νC lags behind the target value of the combustion amount corresponding to the output change. The coal feeding slow velocity dead time element 14 is greatly influenced by the length of the belt conveyor, and the mill dead time element 15 is unique to coal boilers, and is determined by the characteristics of coal as a compressible fluid during the feeding process. This is because it shows that

In other words, the fuel command (item 1! ([)) and the delay in combustion amount are
When the output increases or decreases, there is an imbalance between the generated output and the input fuel! As a result, the main steam temperature fluctuates, which is undesirable.

(Cl @ Akira's Purpose Book @ Akira's Purpose is a steam temperature control method that can prevent the main steam temperature from changing during normal output changes in a power plant and keep the main steam temperature constant C: Obtaining 6: be.

(ctl Structure of the Invention The present invention will be described below with reference to FIGS. 4 to 6.

1 is a block diagram of the fuel control system in the present invention. 1 identical to the one shown in Figure 2! Since the elements are given the same reference numerals, their explanation will be omitted. Reference numeral 17 is a bias setting device with a steam temperature tip, which applies a fuel quantity command (411) in advance before the output changes, and corrects the delay of B M B mill in the coal feeder. be. Moreover, 1B is an electronic meter 1# machine and has an advance bias signal t'ltJ! This is set in the L bias setting 517.

Let us now consider the case where the output is reduced from the current output, that is, the generated power MVP, to the line-of-sight output MWτ by its rate of change M W RC. In this case, the actual fuel injection 1iIFc is delayed with respect to the momentary output command MW as described above. Therefore, in the present invention, the cutting edge advance bias D Y is applied for a period of t before the start of the output drop. Given the leading bias “BIA!I”, the fourth @
As can be seen from I, before the start of output reduction, a deviation occurs between the fuel command and the actual fuel, and a fuel reduction command is issued.

Preliminary bias setting [1 hour, 1 hour.

The output is set before the start time T1 to compensate for the delay time of the mill. Since the operation schedule is predetermined, the time TI is predetermined, and the 11 NI values of 1 after this time τ1 become the time 0.31 hours after the time 0, the output change starts at the time 0. Once reached, the fuel command is given in accordance with the power depletion command. In this case, a preceding command f corresponding to the improvement rate of the fuel command is given, so from the output drop start time T onwards, the preceding command f and command deviation △D are used to reduce the response delay of the feed RIIA and the mill. It is possible to compensate and continuously give fuel injection commands. Therefore, the cutting advance bias DB□, 8 that has already been set is returned to 0.

Next, when the output MY approaches the target value MY, the preceding command fv
In order to gradually cancel the target value, the time tt is increased from the target value arrival time τ.
li] is applied to the + side, and just when the target output is reached, the fuel command and the fuel 1 are applied.
Make sure that C is balanced.

As mentioned above, by applying the advance bias D to one side during the output reduction Bm8 and to the + side when the output reduction is completed, the plant integrated control device ζ: due to the response delay of the coal feeder and mill can be used to generate fuel commands. It is possible to compensate for the difference between the actual fuel and the actual fuel, and can greatly contribute to steam temperature control (2). However, in a system without this circuit, the same effect can be obtained by maintaining the leading edge bias at t''t at time τ1 and returning the leading bias to its original state at time (τa-t*). It is a struggle that is looked down upon.

Now, the above-mentioned calculation and setting operation of the German Deba leading bias grave, as well as the judgment of the timing of each operation, can be done manually, but this! Input/output koji making and calculation control i
The effect of the operation of the present invention can be further enhanced by implementing it by the electronic meter radio 18 consisting of ll. In other words, since the output rate adjustment costs for power plants may be required several times a day depending on the case, it is desirable that they be done automatically. This is because if manual intervention is required each time, the effectiveness will be halved.

゛The magnetic needle NJII18 has a memory that stores the output pattern for one day in advance.

By having a process input/output control device, it is possible to read and store various process inputs such as the generator output and the amount of fuel at that time by having a process input/output control device. I can do it. This electronic calculation 111
118. Details of the setting operation of the BIA8 are shown in the 70-chart of FIG.

The electronic calculation m18 calculates the bias setting time t and the bias setting change rate a in order to output it to the cutting advance bias DB machine A8v bias setter before output deterioration starts. The bias setting time t is empirically obtained as a function of the fuel command at that time.

That is, s tt=r(n). Further, the advance bias amount change rate a may be the same as the output change rate MW1'l. Therefore, a=wvp. Therefore, the lead bias “BIA8”
C"BIAfl""'-t(t:0-t, ),
Time t again.

The signal added to the fuel command as a leading bias during this period is /DBIA8-2@t1.
One of the plant general control devices 1g: It is set in a certain bias setting device 17 (ana cost memory), and the output signal of the bias setting device 17 is added to the fuel command.

As described above, in the present invention, 11 electronic meters are used to set the advance bias setting value t'1llL, and the result is determined by the plant integrated control device 1l1 at the necessary timing when the output changes.
8, and in the plant integrated control device 8, the bias value! It is incorporated into the fuel control system and eliminates the deviation between the fuel command and the actual fuel, in other words, it is possible to provide the output command and the corresponding fuel without response delay, so that fuel input when the output changes does not disturb the steam temperature control. It is possible to obtain the effect of suppressing the steam temperature and preventing the steam temperature from moving back.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a coal-fired power plant, Figure 2 is a block diagram of a conventional fuel control system, Figure 3 is a characteristic diagram of fuel command and combustion amount, and Figure IJ4 is a diagram of the fuel control system of the present invention. The block diagram, FIG. 5 is a characteristic diagram of the fuel flow rate and combustion amount in the present invention, and FIG. 6 is a flowchart showing the operation of setting the blade advance bias. l... Water supply pump 2 River boiler 3... Coal burner 4... Steam pipe 5... Steam control valve 6
...Turbine 7...Ya 1 and Machine 8...
Plant general control device 9... Drive device lO・
...Coal feeder 11...Mill 12m...P engineering operation unit 12B...D operation 'II# required! 13...
・Coal feeder speed delay collection 14...Coal feeder speed dead time 1
1 table 15...Mill dead time wall $16...Conversion screen element 17.
・Advance bias setting device 18 ・Electronic meter 'klIA (7317) Agent Patent attorney Noriyuki Chika (and 1 others)
Figure 5 Figure 6

Claims (1)

[Claims] tilJat so that the deviation between the bonito material command value obtained based on the predetermined operation schedule of the coal-fired power plant 6 and the actual amount of fuel input becomes zero, 1: Therefore, the steam temperature of the coal-fired power plant ! In the case where the fuel command value is controlled to a predetermined value, when the fuel command value changes, the cutting lead bias signal l is added to the fuel command value by the response delay compensation of the fuel supply system, and when the fuel command value starts to change, the fuel command value is changed. A steam temperature control method characterized in that a blade advance bias signal is reset.