JPS599412A - Controller for temperature of reheated steam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reheat steam temperature control device for controlling the humidity of reheat steam in a reheater to an appropriate value in a boiler equipped with a reheater.

Generally, the reheater is installed at the furnace outlet of the boiler.
The temperature of the reheated steam in the reheater depends on the gas humidity at the furnace outlet. Therefore, the reheat steam temperature is controlled by controlling the furnace outlet gas temperature.

Conventionally, the main methods of controlling the furnace outlet gas humidity are burner tilting, gas recirculation amount adjustment, and reheater passing gas amount adjustment (G^S BYP^88BYDAMPER).
was used. However, each of these means has the following drawbacks. In other words, the controllable range of burner tilting is narrow, and it is necessary to use a gas recirculation amount adjusting means in combination.This combination reduces equipment costs such as the gas recirculation fan and gas recirculation duct Y, and reduces the cost of driving the gas recirculation fan. The internal power of the station increases, and the power generation efficiency decreases due to the increase in the station power. If only the gas recirculation amount adjusting means is used, the shaft power of the gas recirculation fan will further increase, equipment costs will increase, and power generation efficiency will further decrease. The means for adjusting the amount of gas passing through the reheater cannot be installed in a boiler with a structure in which a reheater and a superheater are installed inside the furnace, and it is impossible to install a damper for adjusting the amount of gas passing through the reheater. Even if it is, the control response is slow and unfavorable in terms of controllability.

An object of the present invention is to provide a reheat steam temperature control device that can control the reheat steam temperature with good responsiveness without using a gas recirculation fan (excluding the above-mentioned conventional drawbacks).

To achieve this objective, the present invention detects the reheat steam temperature, compares the detected fM degrees with a predetermined target value of the reheat steam temperature and generates an output signal when they do not match; It is characterized in that the distribution ratio of the fuel supply pipes to the burners in each stage is changed by a signal.

The present invention will be explained below based on the embodiments shown in FIGS. 1, 3, and 4.

FIG. 1 is a layout diagram of burners in a boiler.

In this embodiment, the burners are arranged in three stages.

1 is an upper stage burner, 2 is a middle stage burner, and 3 is a lower stage burner. The dotted lines indicate the upper, middle, and lower divisions. 4
Reference numerals 5 and 6.7 indicate fuel supply pipes for supplying fuel to the burners 1.2.3 of each stage, and fuel supply pipes 5, 6.7 branch from the fuel supply pipe 4 at upper, middle and lower stages. Reference numerals 8, 9, and 10 indicate upper, middle, and lower fuel adjustment valves disposed midway between the fuel supply pipes 5, 6, and 7 of each stage;
011.1 The amount of fuel supplied to each burner 1, 2.3 can be controlled by adjusting 10.
2.13 are air dampers for the upper, middle, and lower stages that adjust the amount of secondary air supplied to each stage. In such a burner configuration, the concept of how to control the log gas m degrees out of the furnace and, ultimately, the reheated steam temperature is discussed in the second section.
This will be explained with reference to Figures (a) and (b).

Figure 2(a) is a characteristic diagram showing the distribution of the fuel supply amount to each stage with respect to the turbine load in the burner shown in Figure 1.
Figure (b) is a characteristic diagram showing the relationship between the distribution ratio of fuel supply to the upper burner and lower burner shown in the mt diagram and the furnace outlet gas humidity.

In Figure 2 (α), the horizontal axis shows the load W, and the vertical axis shows the fuel supply 1i.
Q is the answer. The straight line ^1 is the fuel supply pipe 4 shown in Figure 1.
shows the total fuel supply cap supplied from the fuel tank, which increases proportionally as the load increases. Between the straight line M1 and the straight line 3, the fuel supply to the upper stage burner 1 is determined, and between the straight line A and the straight line A8, the fuel supply amount Q to the middle stage burner 2 is determined, and the straight line A
, and the horizontal axis indicate the fuel supply amount Q8 to the lower burner 3.

As shown in the figure, the total fuel supply f for a constant load
& The straight line follows the AI. In this embodiment, the total fuel supply amount is set to 1, and by changing the distribution ratio of fuel supply jiQ+ and 鵡-Qa to each stage burner, the furnace outlet gas temperature is changed and the reheat steam temperature is controlled. be.

In FIG. 2(b), the horizontal axis represents the load W, and the vertical axis represents the furnace outlet gas temperature T. Curve B, when the total fuel supply lid is determined for each load as shown in Figure 2 (b),
When the fuel supply i1Q to the upper burner 1 is maximized (
Therefore, the amount of fuel supplied to murder will decrease. ), and curve B2 shows the furnace exit gas temperature when the fuel supply amount Q3 to the lower burner 1 is maximized (the supply amount to the murder is decreased). From the figure, it is clear that the contribution to the furnace exit gas humidity T is large in the upper stage burner 1 and small in the lower stage burner 3. Therefore, changing the distribution ratio of the fuel supply amount to each stage will affect the furnace exit gas temperature. This means that it can be controlled. song! at and curve B2
The area between is the range in which the furnace outlet gas temperature can be controlled.

FIG. 3 is a block diagram of a reheat steam temperature control device based on the above idea.

In FIG. 3, 15 is a boiler input signal. The boiler input signal 15 is a signal for fuel flow to obtain the currently required amount of steam, which is corrected by the difference between the predetermined amount of steam suspended by the load and the actual amount of steam. Secure the steam turtle. 16 is a reheat steam temperature correction signal. The reheat steam temperature correction signal 16 is a correction signal of the combustion device for correcting the humidity difference between the target value of the reheat steam humidity and the actual reheat steam humidity. 17, 18, and 19 are upper, middle, and lower burner control circuits. The control circuit 17 in the upper stage receives the boiler human power signal 15 as well as the 1 reheat steam temperature correction signal 16 . In this case, the reheat steam humidity correction signal @16 is added to the boiler human power signal 16 if the reheat steam temperature is below the target value, and is subtracted from the boiler input correction signal 16 if it is above the target value. On the contrary, in the lower stage PANA control circuit 19, the reheat steam temperature correction signal 16 is subtracted from the boiler input signal @16 if the reheat steam temperature is below the target value, and the reheat steam temperature correction signal 16 is subtracted from the boiler input signal @16. If it is greater than the value, it will be added to this. 20a, 21a
, 22α are fuel supply amount transmitters for the upper stage, middle stage, and lower stage, respectively, which feed back the current fuel supply amount. 20b, 21b% 22b are upper, middle and lower air supply amount transmitters, respectively, which feed back the current air supply amount. 23α, 24a, and 25α are the upper, middle, and lower stage fuel supply amount control circuits, respectively, and each transmits the fuel supply amount! ii! 20G, 21C122α, and the outputs of the upper, middle, and lower burner control circuits M17, 18, and 19 are manually generated. 23be, 24b, and 25b are upper, middle, and lower air supply amount control circuits, respectively. I am typing. These fuel supply amount control surfaces M23α.

24cL, 25α, and air supply amount control circuit 23b,
By the outputs of 24b and 25b, the upper, middle, and lower fuel adjustment valves 8, 9.10 and air dampers 11, 12.1 are activated.
Control 3.

Here, an outline of the operation of this control device will be explained.

The boiler input signal 15 is a signal corresponding to the amount of fuel supplied to obtain the required amount of steam at that time. If the reheat steam temperature is below the target value, the reheat steam temperature correction signal 16 will have a value corresponding to the amount of fuel supply required to correct this temperature discrepancy. Upper burner control circuit 17
, the fuel supply amount target value for the upper stage burner 1 is output by adding the reheat steam temperature correction signal 16 to the boiler input signal 15. In the upper stage fuel supply amount control circuit 23G, the fuel supply amount signal currently being supplied from the upper stage side fuel supply amount axis signal device 20G and the upper stage burner control circuit 1
7 and outputs the deviation value. Using this way of output, the upper fuel adjustment valve 8 is controlled so that the fuel supply lid increases. On the other hand, in the lower burner control circuit 19, the target value of the fuel supply amount to the lower burner 3 is obtained by subtracting the reheat steam temperature correction signal 16 from the boiler input signal 15. The lower stage fuel supply & amount control circuit 25G compares the fuel supply amount signal currently being supplied from the lower stage fuel supply amount transmitter 22α with the fuel supply amount target value from the lower stage burner control circuit 19. Output the deviation value. This output is used to control the lower fuel adjustment valve 1° so that its fuel supply amount is reduced.

That is, when the reheat steam temperature is lower than the target value, the amount of fuel supplied to the upper stage burner 1 is increased, and at the same time, the amount of fuel supplied to the lower stage burner 3 is decreased, and as explained in FIG. The gas temperature is raised and the reheated steam temperature is increased to match the target value. In this way, the reheat steam temperature can be controlled by changing the distribution ratio between the upper and lower fuel supply lids using the reheat steam temperature correction signal 16. It should be noted that in this farm, the reheated steam temperature correction signal 16 is not input to the middle stage burner control circuit 18, and no control is performed based on this signal. Also, upper and lower burner control (b) path 1
7.19, the same signal is positive on one side and negative on the other, so the total fuel supply remains unchanged. 0 When the reheat steam temperature is higher than the target value, contrary to the above operation, the reheat steam temperature The correction signal 16 is subtracted by the upper burner control circuit 17 and added by the lower burner control circuit 19. Note that the air supply amount control is performed in the same manner as the fuel supply amount control, so a description thereof will be omitted.

FIG. 4 is a block diagram showing an example of an integral part of the reheat steam temperature control device shown in FIG. 3.

In Fig. 4, 26 is a main steam pressure transmitter that generates a signal according to the airless pressure that enters the high pressure turbine from the boiler superheater outlet, and 27 is a main steam pressure transmitter that is set for a predetermined boiler load. A main steam pressure set value transmitter 28 that generates a signal according to the steam pressure is a first comparator that compares the output signals of the main steam pressure transmitter 26 and the main steam pressure set value transmitter 27. Reference numeral 29 denotes a first proportional-integral calculator which outputs eccentricity in accordance with the deviation signal when the deviation signal is output from the l-th comparator 28. This first proportional-integral calculator 29 performs a proportional-integral operation commensurate with the deviation signal, and at the initial stage of the response performs a proportional operation that outputs a signal at a predetermined level with a gain adjusted according to the deviation signal. After that, the integral action is applied to cancel out the deviation.

Reference numeral 30 is a steam amount setting signal corresponding to the required steam amount determined by the load, and is an input signal for obtaining the necessary boiler generated steam required from the load/steam flow rate ratio. 31 is the output of the first proportional-integral calculator 29 and the steam amount setting signal 30
The output base of this adder 31 is IM-adjusted to the fuel amount according to the added value. 32 is a total fuel supply amount transmitter, which indicates the total amount of fuel supply suspended due to the load, that is, 1°2 for each of the upper, middle, and lower burners.
．． A signal corresponding to the total number of fuel caps to be supplied to No. 3 is output. A second comparator 33 compares the output signal of the adder 31 and the output signal of the total fuel supply amount transmitter 32, and outputs the difference thereof. 34 is a second proportional-integral calculator;
It has the same function as the l-th proportional-integral calculator 29. 35 is a multiplier.

The multiplier 35 is provided for the purpose of correcting the change in boiler characteristics due to the number of stages of the burner. For example, if the number of stages is only one, the deviation signal output from the proportional-integral calculator 34 is corrected so that it becomes slightly larger, and conversely, when a plurality of stages, for example three burners, are used, it is corrected so that it becomes slightly smaller. Note that the multiplier 35 is not necessary if there are no particular problems as a result of operation. Reference numeral 36 is a manual/automatic operating device which allows required signals to be input manually.

37, 38, and 39 are the first adder in the upper stage and the first adder in the middle stage, respectively.
The adder is the first adder in the lower stage. Adder 3 of each of these stages
7, 38, and 39 are each adjusted to a level corresponding to 1/3 of the predetermined total fuel supply and equipment depending on the load. The upper first adder 37 has a manual/automatic operator 36.
and the same reheat steam temperature correction signal 16 as described in the description of FIG. 3 are input and summed.

The output of this upper stage first adder 37 is a value corresponding to the target value of the fuel supply amount to the upper stage burner 1. 40 is a ratio setter. In the case of this embodiment, the boiler is a mixed combustion of oil and gas, and the ratio setter 40 (determines the mixed combustion ratio of the boiler). This is a multiplier for multiplying the ratio of oil, and multiplier 41
The output signal becomes the target value of the oil supply amount. 20α8 is
This is an upper fuel oil flow rate transmitter corresponding to the upper fuel supply amount transmitter 201m shown in FIG. 3, and transmits a feedback signal of the flow rate of oil currently being supplied. 42 is a comparator that compares the signal from the multiplier 41 and the signal from the upper fuel oil flow rate transmitter 20α1, and the comparator 42 detects the deviation between the actual supply amount and the target supply amount. 43 is 1
This third proportional-integral calculator has the same function as the proportional-integral calculator 29, and performs proportional operation and integral operation according to the deviation signal of the comparator 42, and outputs a signal at a level suitable for control.

The output signal of the third proportional-integral calculator 43 is used as a control signal for the upper stage fuel oil regulating valve.

44 is an upper stage silk 2 adder, which calculates the output of the multiplier 41 from the output of the upper stage l adder 37 (upper stage fuel supply amount target value).
Subtract oil accompaniment #8M@spear value). The output of the upper stage 2 adder 44 (is the m value of the supply amount of 1 gas. 20 Gm is the upper R (Ill fuel gas flow position transmitter) 45 is the comparator of the vessel 4,
Reference numeral 46 denotes a fourth proportional-integral calculator, which corresponds to the comparator 42 and the third proportional-integral calculator 43 of the upper fuel oil flow rate transmitter 20α11-3, respectively. The output signal of the proportional-integral calculator 46 of the candy 4 is used as a control signal for the fuel gas adjustment valve in the upper stage. The configuration within the dashed line is the upper stage fuel supply lid control circuit 23α, which is also shown in FIG.

Note that the fuel oil dispersion transmitter 1 fuel gas flow rate transmitter and the fuel supply 1 control circuits 24α and 25a in the middle and lower stages have the same configuration as those in the upper stage, so illustration and description will be omitted. The air body device control circuit is also illustrated)
The explanation will be omitted.

Next, the operation of this specific example will be explained.

A signal corresponding to the steam pressure in the high-pressure turbine is output from the main steam pressure transmitter 26, and this signal is compared with a signal corresponding to the set value from the main steam pressure set value transmitter 27 in the first comparator 28. be done. When the steam pressure in the high pressure turbine is lower than the set value, the comparator 28 of w41 outputs, for example, a deviation signal of a positive predetermined level. When the first proportional-integral calculator 29 outputs this deviation signal, it initially amplifies the deviation signal with the adjusted gain and produces an output that is approximately proportional to this deviation signal, but as time passes, Integral action is involved. The output signal of the first proportional-integral calculator 29, which should compensate for the lack of steam pressure, is added to the signal 30 corresponding to the required amount of generated steam suspended by the load in the adder 31, and the currently required steam lid is created. It will be done. Adder 31
Since the output base of is adjusted to the base of the fuel amount according to this steam amount, the output becomes a signal according to the required fuel supply amount. This signal is combined with a signal from the transmitter 32 corresponding to the total fuel supply amount determined by the load and a second comparator 33.
compared in. If the former is large, for example, a positive deviation signal of a predetermined level is output from the second comparator 33. This deviation signal operates the second proportional-integral calculator 34,
By the same operation as the first proportional-integral calculator 29, the second
A predetermined output signal is generated from the proportional-integral calculator 34. This output signal is corrected by the multiplier 35 according to the number of stages a, and then passed through the manual/automatic controller 36 to the first addition 1 of each stage.
37, as, and 39 respectively.In the end, the signal output from the multiplier 35 becomes a signal corresponding to the fuel supply amount to be corrected in order to secure the amount of steam required by the boiler.

The open l adders 37, 38, and 39 at each stage adjust the level KN to 1/3 of the total fuel supply amount as described above, and by adding the output signal of the multiplier 35 to this, the required steam The amount of fuel supplied to ensure the required amount of fuel can be obtained. On the other hand, when the reheated steam temperature is lower than the target value, the 1 reheated steam temperature correction signal becomes, for example, a positive predetermined level signal. In order to obtain such a reheat steam temperature correction signal, for example, a reheat steam temperature transmitter that detects the reheat steam temperature and generates a signal according to the detected temperature, and a predetermined reheat steam temperature transmitter that detects the reheat steam temperature and generates a signal according to the detected temperature, Control using a reheat steam temperature set value transmitter that generates a signal according to the heat steam temperature, a comparator that compares the output signals of both distributors, and a proportional integral calculator that generates an output based on the deviation signal of the comparator. Just configure the circuit. The reheated steam temperature correction signal 16 of the pressure (well, it is added in the upper stage first adder 37 to increase the fuel supply amount to the upper stage burner.
The adder 39 adds a minus value to reduce the fuel supply amount to the lower burner. Therefore, the distribution ratio between the upper and lower fuel supply needles is changed, and the amount of fuel supplied to the upper stage is increased, which increases the boiler furnace outlet gas temperature and raises the reheat steam temperature to the target value. In this case, the reheat steam temperature correction signal 16 having the same value is added by the upper stage #11 adder 37, and the middle stage #11 addition 1i! 38, but is subtracted by the lower first adder 39, so the total fuel supply amount remains unchanged. In the end, each stage's adder 37, 38゜3
9 outputs a signal corresponding to the target value of the fuel supply needle of each stage.

As described above, the output signal of the first adder 37 in the upper stage is divided into signals according to the target value of fuel oil supply amount and the target value of fuel gas supply amount by the ratio setter 40, the multiplier 41, and the second upper stage adder 44. The upper stage fuel oil flow rate transmitter 20cL and the upper stage fuel generate feedback signals according to the fuel oil supply amount and fuel gas supply amount currently supplied to the upper stage burner. The signal from the gas flow rate transmitter 20a and #! s t It is compared by the fourth comparator 42.45, and the third and fourth
An output is generated in the proportional integral calculators 43 and 48, and this output signal controls the upper stage fuel oil regulating valve and the upper stage fuel gas regulating valve, so that a desired amount of fuel can be supplied to the upper stage burner. The same applies to the middle and lower rows. In addition, in order to equalize the temperature distribution in the furnace, the middle stage adder 3
Adjustment is made by inputting the outputs of the upper stage adder 37 and the lower stage first adder 39 to 8.

As described above, in this embodiment and its specific examples, in order to obtain a necessary steam cover for the boiler, a means for obtaining a boiler input signal corresponding to the fuel supply IT is provided, and the reheat steam temperature is A means is provided to generate a reheat steam temperature correction signal when it does not match the target value, and this reheat steam humidity correction signal is used to change the distribution ratio of the fuel supply amount in the upper and lower stages. It is possible to control the reheating steam temperature with good responsiveness without using it, and it is also possible to secure the steam lid necessary for the boiler.

Note that the number of stages of the burner may be two, or even if the number of stages is four or more, the distribution ratio of the fuel supply lid can be changed as appropriate.

As described above, in the present invention, means is provided for generating an output signal when the reheat steam temperature does not match the predetermined target value, and the distribution ratio of the fuel supply lids of each stage is changed by this output signal. This makes it possible to control the reheat steam temperature with good responsiveness without using a gas recirculation fan.

[Brief explanation of the drawing]

Figure 11 is a burner layout, Figures 2 (a) and (b) are characteristic diagrams of fuel supply amount and furnace outlet gas temperature with respect to boiler load, and Figure 3 is reheat steam temperature control according to an embodiment of the present invention. 4 is a block diagram showing a specific example of the reheat steam humidity control device shown in FIG. 3. FIG. 1... Upper burner, 2... Middle burner, 3...! Lower burner, 8, 9, 10...
・Fuel adjustment valve, 16... Reheat steam temperature correction signal, 17... Upper burner control circuit, 18...
...Middle burner control Igl path, 19...Lower burner control circuit, 20α...Upper stage fuel supply amount transmitter, 21α...Middle stage fuel supply amount transmitter, 2
2cL・・・Lower side fuel supply amount transmitter, 23α・
...Lower stage fuel supply amount control circuit, 24a...
-Middle stage fuel supply amount control circuit, 25G...Lower stage fuel supply amount control circuit, 37...Upper rR11 adder, 38...Middle stage first adder, 39...・・・・・・
Lower stage l adder.

Claims (1)

[Claims] 1. In a boiler equipped with a reheater, multiple stages of burners, and a fuel supply amount adjustment device provided in each of these stages,
means for generating an output signal when the reheat steam temperature of the reheater does not match a predetermined target value of the reheat steam temperature;
A reheat steam humidity control device characterized by further comprising means for changing the distribution ratio of the amount of fuel supplied to the burners in each stage based on the output signal! .