JPS63217111A - Boiler-superheater metal-temperature automatic controller - 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] [Industrial Application Field] The present invention relates to a boiler superheater metal temperature automatic control device,
In particular, the present invention relates to an automatic boiler superheater metal temperature control device suitable for automatically controlling the superheater metal temperature of a boiler equipped with an after-air port.

- [Prior Art] Fig. 4 is a block diagram of a boiler system equipped with an after-air port.

A wind box 1 into which secondary air is introduced is provided on the side of the boiler 100, and a burner 2 is disposed within the wind box 1.

A ninth after air port (AAP) 3 is provided on the boiler side wall above the burner 2 to lower the boiler exhaust gas temperature.
A part of the secondary air supplied to the wind box 1 is introduced via the damper 8.

On the downstream side of the boiler 100, superheaters 4a and 4b are provided to superheat low-temperature steam and supply it to the turbine 5. A desuperheater 6 is disposed between the connections of the superheaters 4a and 4b, and through water is supplied via a spray valve 7 to be mixed with the high temperature steam output from the superheater 4a. Further, the damper 8 is controlled by a damper control driver 9 to an opening degree vI, which is controlled by a control system having a configuration shown in FIG.
4 adjustments are made.

Next, the operation of the configuration shown in FIG. 4 will be explained.

The fuel supplied from the burner 2 is mixed with secondary air and burned within the boiler 100. The exhaust gas from the combustion passes through the superheaters 4b and 4at and is discharged to the outside of the boiler. The superheaters 4a and 4b exchange heat with exhaust gas,
The supplied fish and shellfish are heated and the high temperature fish and shellfish are supplied to the turbine 5.

If the temperature of the exhaust gas in the boiler 100 increases, the amount of unburned matter in the exhaust gas will increase, and the temperature of the tube metals of the superheaters 4a and 4b will increase, causing damage to the superheaters 4a and 4b.

In order to prevent this, a method is adopted in which a part of the secondary air is introduced into the after-air port 3 by opening the damper 8 and thrown into the high-temperature boiler combustion gas.

Furthermore, in order to keep the temperature of the main steam supplied to the turbine 5 constant, the spray valve 7 is adjusted according to the rise in main steam temperature, and the desuperheater 6 sprays water into the steam.

FIG. 5 is a block diagram showing the structure of a conventional control system for controlling the after-air port 3. As shown in FIG.

Based on the power supply command (MWD) 11 (or the actual boiler load), the function generator 12 generates a damper opening signal corresponding to each load. The output signal of the function generator 12 is converted by the electric-air converter 13, and then drives the control driver 9, opens and closes the damper 8, and adjusts the amount of secondary air supplied to the after-air port 3. As a result, the internal temperature of the boiler 100 is brought to an appropriate temperature, and it is possible to avoid a reduction in unburned matter and an abnormal rise in the tube metal temperature.

[Problem that the invention seeks to solve]

However, with the conventional boiler internal gas temperature and superheater metal temperature control means, the amount of after air released is uniquely determined by the boiler load, so fine control of the after air cannot be performed. Therefore, if the operating conditions change, there is a possibility that the after-air tray will deviate from the optimal setting.

For example, if you are planning to use the upper stage burner for after-air settings, if you use the lower stage burner in the next operation,
Even though the temperature of the superheater metal becomes difficult to rise, the set amount of air, that is, more electricity than is required, will be input, and the unburned content will increase due to the 02 drop in the burner zone. On the other hand, if it is set so that the lower stage burner is used, there is a problem that the metal temperature rises excessively when the upper stage burner is used. Furthermore, the optimum settings may deviate when the coal type is changed or due to changes over time such as dirt on the tube metal.

Furthermore, cooling the main steam once it has been superheated with spray water is a waste of energy, and although it is desirable to use as little spray water as possible, no consideration has been given to this point.

An object of the present invention is to provide an automatic boiler superheater metal temperature control device that enables automatic control of superheater tube metal temperature while minimizing the use of spray water.

[Means for solving problems]

In order to solve the above problems, the present invention provides spray water to be supplied to the superheater based on an increase in main steam temperature, and
In a boiler where after-air damping is carried out based on a load command, the after-air damper is adjusted based on the deviation between the spray wood cover set value for each load based on the load command and the detected value of the spray water supply amount to the superheater. The present invention is constructed by providing a correction means for correcting the opening command value.

[For production]

According to the above means, the after air damper opening command set using the spray water supply amount as a feedback signal can increase or decrease the after air supply area in accordance with the rise or fall of the tube metal temperature of the superheater. The entire automatic boiler superheater metal temperature control system can be configured without reducing controllability, such as by increasing the opening number of the spray valve.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing an automatic boiler superheater metal temperature control device according to the present invention, and FIG. 2 is a diagram showing a boiler to which the present invention is applied. In Figures 1 and 2, the same reference numerals are used for the same parts as in Figures 4 and 5, so repeated explanations will be omitted.

First, the spray 9f70 control system will be explained.

As shown in FIG. 2, a temperature transmitter 15 is connected to the outlet side of the superheater 4b to output the main steam temperature.

A subtractor 16 is connected to the temperature transmitter 15, and the deviation from the main steam temperature set value is calculated. A PI regulator 17 is connected to the subtractor 16, and an electro-nitrogen converter (E/P) 13 connected to the PI regulator 17 controls the spray valve 7.
is adjusted.

The deviation between the main steam temperature detected by the temperature/reaction transmitter 15 and the preset main steam temperature set value is taken by the subtractor 16, and this deviation value is subjected to proportional and integral processing by the PI controller 17. The signal is converted by an electric-air converter 13. The spray valve 7 is controlled based on this i-change signal,
Spray water corresponding to the main steam temperature deviation is supplied to the attemperator 6 to adjust the main steam temperature.

Next, after-air control according to the present invention will be explained.

As shown in FIG. 2, a flow rate transmitter 18 for detecting the flow rate of spray water is connected to the spray valve 7 and the water supply channel of the attemperator 6, and the detected flow rate value is output to a subtractor 19.

On the other hand, a function generator 12 and a function generator 12 which input the power supply command MWD (boiler load) are provided. The function generator 12 outputs an after-air (AAP) damper opening degree command, and the function generator 12 outputs the spray amount at each load. Function occurrence 0
The AAP damper opening degree command and # by the user and the spray flow rate detection value by the amount transmitter 18 are input to a subtracter 19, and a PI regulator 21 and an adder n are connected to this subtracter 19 in sequence. In addition to the output of the PI regulator 21, the output of the function generator 12 is applied to the adder B, and both inputs are added.

An electric-to-air converter 0 is connected to the adder a, and the damper control driver 9 is connected to the electric-to-air converter.
is controlled.

A subtracter 19 takes the deviation between the slickness amount setting value outputted from the function generator and the spray flow value detection value (actual measurement value), and this deviation value is integrated by the PI adjustment heat 21. The output value of the PI adjuster 21 and the damper opening command output from the function generator 12 are added by an adder n, and the deviation amount of the damper opening command is corrected. After the output of the adder 04 is electrical-pneumatically converted, the spray valve 7 is regulated by the converted signal.

When the tube metal temperature of superheaters 4a and 4b rises,
The steam temperature within the superheaters 4a, 4b also increases.

When the steam temperature rises, the spray valve 7 opens so that the temperature returns to the preset main steam temperature, spray water corresponding to the temperature deviation amount is injected, and the main steam temperature is lowered to a predetermined value.

At this time, an after air damper opening command that depends on the spray water is created based on the deviation between the spray flow IT detection value and the set value, and is added to the after air damper opening signal set as a function of the power supply command, and the spray (N By correcting the damper opening command by the operator, it is possible to obtain the optimum amount of after air required to prevent the temperature of the superheater tube metal from rising.

The function generation participation is set so as to output a characteristic in which the boiler load and the amount of spray water form a mountain shape, as shown in FIG.

As described above, since the main steam temperature can be controlled by the air waves of the after-air port, the frequency of opening and closing of the spray valve can be reduced compared to the conventional method, and controllability can be improved.

Furthermore, the rangeability of the spray valve can be reduced.

〔Effect of the invention〕

As described above, according to the present invention, the tube metal temperature of the superheater can be automatically controlled, thereby extending the life of the superheater tube and preventing accidents such as breakage of the superheater tube.

Furthermore, since it is possible to input the minimum amount of after-air required, it is possible to suppress an increase in unburned content and prevent a decrease in boiler efficiency.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of the present invention, Fig. 2 is a configuration diagram showing a boiler to which the present invention is applied, and Fig. 3 is a block diagram showing an embodiment of the present invention.
Fig. 4 is a block diagram showing an example of a boiler system equipped with an after-air port, and Fig. 5 is a block diagram showing a control system of a conventional after-air port damper. . 2...burner, 3...after air blow), 4a. 4b... Superheater, 6.16... Desuperheater, 7... Spray valve, 8... Damper,
9...Control driver, 11...
・Power supply command, 12.20...Function generator, 13
, Z3... Electricity-air converter, 15...
・Temperature transmitter, 17.21...PI controller, 1
8...Flow rate transmitter, 19...Desuperheater,
n... Adder. Figure 1 Figure 2 Figure 3 Hon Ira Koei □ Figure 4 Figure 5

Claims (1)

[Claims] (1) In a boiler where spray water is supplied to the superheater based on a rise in main steam temperature and the amount of after air is adjusted based on a load command, the spray water amount setting value for each load based on the load command is An automatic boiler superheater metal temperature control device comprising a correction means for correcting an after-air damper opening command value based on a deviation from a detected value of spray water supply amount to the superheater.