JPH0658509A - Bed temperature control method for fluidized bed boiler - Google Patents

Abstract

PURPOSE:To keep optimum the bed temperature of a fluidized bed by increasing the amount of a sludge when the bed temperature exceeds a predetermined upper limit while decreasing the same when the bed temperature becomes lower than a predetermined lower limit. CONSTITUTION:A detection signal by a bed temperature detector 6 on a fluidized bed is inputted into an adjuster 7. The adjuster 7 issues an increase/ decrease operation signal of the amount of the incorporation of a sludge correspondingly when bed temperature becomes greater or lower than an upper limit/lower limit. With this signal, a sludge supply installation 3 is operated, and hence the amount of a sludge incorporated onto a fluidized bed layer is increased/decreased. Thus, heat absorption on a fluidized bed layer surface is increased/decreased, and hereby the bed temperature in the fluidized bed layer becomes lower/higher to be kept at a predetermined value. Further, main steam pressure is kept at a specified value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bed temperature control of a fluidized bed boiler using sludge as a fuel.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, the main steam pressure at the boiler outlet 2 of a fluidized bed boiler 01 is detected by a pressure detector 4, and the detection signal 4 is input to a controller 5 for adjustment. 5 in total
To the fuel control valve 1 via the high / low signal selector. This signal regulates the fuel control valve 1 in the fluidized bed.

On the other hand, a bed temperature detector 6 is installed in the fluidized bed, and the detection signal 6 is input to the controller 8 to make the controller 8
The output signal from is input to the high / low signal selector 9. The high / low signal selector 9 operates the control valve 1 in the fluidized bed by the output signal of the controller 5 on the outlet side of the boiler and the high / low output signal of the controller 8 on the fluidized bed side. Was there.

[0004]

According to the conventional technique, as shown in FIG.
If the bed temperature in the fluidized bed is higher than the upper limit / lower than the lower limit, the signal is selected by the high / low signal selector 9 to decrease / increase the fuel control valve 1 in the fluidized bed to increase the bed temperature. Was in control. However, in this method, when the bed temperature control signal is selected by the selector 9, the boiler main steam pressure cannot be controlled well. Furthermore, the fuel in the fluidized bed has a minimum flow rate /
Since there is a maximum flow rate, it may not be possible to try to decrease / increase the fuel in the fluidized bed to increase / decrease the bed temperature, and there is a risk that optimal bed temperature control may not be possible.

[0005]

The present invention takes the following means in order to solve the above problems. That is, as a bed temperature control method of a fluidized bed boiler, in a controller of a fluidized bed boiler that inputs sludge onto a fluidized bed, the bed temperature is detected, and if the bed temperature becomes higher than a predetermined upper limit value, the amount of sludge is increased. Was adjusted so as to increase, and the sludge amount was adjusted so as to decrease when the value became lower than a predetermined lower limit value, so that the bed temperature was kept at the optimum value.

[0006]

By the above means, when the bed temperature in the fluidized bed becomes higher than the predetermined upper limit value, a large amount of sludge is added from above the bed, the heat absorption on the fluidized bed surface increases, and the bed temperature in the fluidized bed layer increases Becomes low and the bed temperature is maintained at a predetermined level. Further, when the amount becomes less than the predetermined lower limit value, a small amount of sludge is added and the bed temperature is maintained. This change is due to the property that the sludge contains a large amount of water.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. It should be noted that the parts described in the conventional example are denoted by the same reference numerals and the description thereof is omitted, and the parts relating to the present invention will be mainly described.

The output of the bed temperature detector 6 of the fluidized bed is sent to the sludge supply equipment 3 via a controller 7.

The output of the steam pressure detector 4 at the boiler outlet is sent to the fuel control valve 1 in the fluidized bed via the controller 5.

In the above, the detection signal of the bed temperature detector 6 is input to the controller 7. When the bed temperature is above the upper limit value / below the lower limit value in the controller 7, the input / output increase / decrease operation signals are output correspondingly. This signal operates the sludge supply equipment 3 to increase / decrease the amount of sludge injected onto the fluidized bed.

Therefore, a large amount of heat is absorbed on the surface of the fluidized bed /
The bed temperature in the fluidized bed is lowered / increased to be maintained at a predetermined temperature.

Further, by adding a large amount / a small amount of sludge, the total fuel amount increases / decreases, so that the main steam pressure tends to become higher / lower than the specified value. This pressure is detected by the pressure detector, and is passed through the controller 5 to decrease / increase the fuel control valve 1 in the fluidized bed. Therefore, the amount of fuel in the fluidized bed also decreases / increases, the bed temperature also decreases / increased, and the main steam pressure is maintained at a specified value.

As described above, a safe boiler operation can be achieved by controlling the amount of sludge fed into the fluidized bed so that the bed temperature does not exceed the upper limit value / lower limit value.

Further, stable bed temperature control can be obtained regardless of the lower limit / upper limit flow rate of the fuel in the fluidized bed. further,
Boiler main steam pressure control can be obtained because there is no restriction on the fuel in the fluidized bed by the bed temperature.

[0015]

As described above, according to the present invention, a safe boiler is operated by controlling the amount of sludge fed into the fluidized bed so that the bed temperature does not exceed the upper limit value / lower limit value. You can drive.

[Brief description of drawings]

FIG. 1 is a configuration system diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional example.

[Explanation of symbols] 1 Fuel control valve in fluidized bed 2 Main steam pipe at boiler outlet 3 Sludge supply equipment 4 Steam pressure detector at boiler outlet 5 Controller 6 Bed temperature detector 7 Controller

Claims (1)

[Claims] 1. A control device for a fluidized bed boiler, which inputs sludge onto a fluidized bed, detects a bed temperature, and adjusts the sludge amount to increase when the bed temperature becomes higher than a predetermined upper limit value, If it becomes lower than the specified lower limit,
A bed temperature control method for a fluidized bed boiler, which is characterized in that the sludge amount is adjusted to be reduced to maintain the bed temperature at an optimum value.