JPH0366567B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION The present invention relates to a method for controlling combustion air flow rate and exhaust gas exhaust flow rate in an incinerator.

In conventional waste incinerators, the combustion air flow rate and the exhaust gas exhaust flow rate are controlled only by dampers. Therefore, the forced air blower and induced air blower must be driven so that the air flow rate is always greater than the maximum value of the combustion air flow rate and the maximum value of the exhaust gas exhaust flow rate. There was a problem with power consumption.

The combustion air flow rate and exhaust gas discharge flow rate control method in an incinerator according to the present invention is such that the combustion air flow rate is controlled so that the furnace temperature and furnace pressure become appropriate values based on the detection signals of the furnace temperature detector and the furnace pressure detector. The exhaust gas discharge flow rate is controlled by the damper, and the air flow rate of the forced air blower and induced air blower is controlled based on the measured value of the generated steam flow rate of the waste heat boiler. It is determined based on the appropriate combustion air flow rate for the measured value of the generated steam flow rate calculated from the measured value and the predetermined relationship between the generated steam flow rate of the waste heat boiler and the appropriate combustion air flow rate, and the air flow rate of the induced blower is From the temperature adjustment blower to the appropriate combustion air flow rate calculated from the measured value of the generated steam flow rate and the predetermined relationship between the generated steam flow rate of the waste heat boiler and the appropriate combustion air flow rate. It is characterized in that the measured value of the air flow rate being sent to is determined based on the added value.

In the present invention, the combustion air flow rate and the exhaust gas discharge flow rate are controlled by the damper based on the detection signals of the furnace temperature detector and the furnace pressure detector so that the furnace temperature and furnace pressure become appropriate values. ,
Since the air flow rate of the forced air blower and induced air blower is controlled based on the measured value of the flow rate of steam generated by the waste heat boiler, the air blower can be driven efficiently and the power consumption of the air blower can be saved.
Highly accurate control can be performed even near the lower limit and near the upper limit of the air amount control range, and control with high responsiveness can be performed.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows an incinerator 1 showing a waste incinerator.
is equipped with a waste heat boiler 2. A steam flow rate detector 4 is provided in the steam extraction passage 3 of the boiler 2 . Combustion air from the forced air blower 5 passes through the main air passage 6a and three branch air passages 6b branched from the main air passage 6a to the drying grate hopper 1a, combustion grate hopper 1b, and back of the incinerator 1. Each is sent to the grate hopper 1c. A fire spread air amount adjusting damper 7 is provided in the middle of each branch air passage 6b. Air from the temperature regulating blower 8 is sent into the incinerator 1 through an air passage 9. An air amount adjustment damper 10 for temperature adjustment is provided in the middle of the air passage 9. Further, a temperature adjustment air flow rate detector 11 is provided between the damper 10 of the air passage 9 and the incinerator 1 to detect the amount of temperature adjustment air sent into the incinerator 1 .

The exhaust gas generated in the incinerator 1 passes through an exhaust gas treatment device 12, is sucked in by an induced blower 14 installed in a flue 13, and is discharged into a chimney 15. A furnace pressure regulating damper 16 is provided in the middle of the flue 13.

As is well known, each damper 7, 10, 16 controls the temperature within the furnace by the central controller 17 based on detection signals from a furnace temperature detector (not shown) and a furnace pressure detector (not shown). And the furnace pressure is automatically controlled to maintain an appropriate value.

Each blower 5, 8, 14 is driven by a drive motor 5a, 8
a, 14a. Drive motor 5
a, 8a, 14a are drive control circuits 5b, 8b, 1
The drive is controlled by 4b. Each blower 5, 8,
14 air blowing amount (suction amount), that is, the drive motor 5
The rotational speeds of a, 8a, and 14a are determined by the blower control device 2.
Controlled by 0.

FIG. 2 shows the configuration of the blower control device.
The control device 20 includes a central processing unit (CPU) 21 and a clock pulse generator 22 that generates pulses at regular intervals (for example, 30 seconds to 5 minutes). CPU21 memorizes the program
ROM23 and RAM2 that stores various data
It is equipped with 4.

1 and 2, the CPU 21 includes a pulse signal outputted from the clock pulse generation circuit 22, a steam flow rate detection signal from the steam flow rate detector 4, and a steam flow rate detection signal from the temperature adjusting air flow rate detector 11. Air flow detection signal for temperature adjustment and central control unit 16
Damper control signals sent from the dampers 7 and 16 to the dampers 7 and 16, respectively, are input via the input port 25. From CPU21, each blower 5, 8, 14
A speed designation signal designating the rotational speed of the motors 5a, 8a, 14a is outputted to each motor drive control circuit 5b, 8b, 14b via the output port 26, respectively.

The appropriate combustion air flow rate Qf for combusting waste in an appropriate combustion state is the lower calorific value of waste.
Letting Hu and the amount of waste incineration be R, it can be expressed by the following formula.

Qf=K1・Hu・R...(1) K1: Constant In addition, the flow rate of steam generated in the waste heat boiler Qs can be expressed by the following formula.

Qs=K2・Hu・R (2) K2: Constant Therefore, the appropriate combustion air flow rate Qf can be expressed as follows using the generated steam flow rate Qs.

Qf=(K1/K2)Qs...(3) =K3・Qs...(4) However, K3=K1/K2 The constant K3 can be determined in advance by experiment.
Therefore, the appropriate combustion air flow rate Qf can be determined from the measured value of the generated steam flow rate. However, since there is a time delay between when combustion air is sent into the incinerator and when the steam flow rate corresponding to the combustion air flow rate appears, the appropriate combustion air flow rate Qf calculated using equation (4) above is Contains errors due to time delays. Since the combustion air flow rate is ultimately controlled by the damper 7, if the air flow rate QF of the forced air blower 5 is set to a value larger than the appropriate combustion air flow rate Qf by at least the maximum error due to time delay,
The damper 7 compensates for the error. Therefore, in this embodiment, the air flow rate QF of the forced air blower 5 is calculated by multiplying the appropriate combustion air flow rate Qf by a predetermined constant A1 of 1 or more (1.1 to 1.5). In other words, QF is calculated by the following formula.

QF=A1・Qf ……(5) =A1・K3・Qs ……(6) Since the air flow rate of the temperature adjustment fan 8 is smaller than that of the other blowers 5 and 14, the air flow rate determined in advance is It is set to a value equal to the maximum value of the temperature adjustment air flow rate. In other words, the temperature adjusting air flow rate is controlled only by the damper 10.

The air flow QI of the induced air blower 14 is determined by the following equation.

QI=A2・(Qc+Qf) ……(7) Here, A2 is a predetermined constant from 1.3 to
It is about 1.7. Moreover, Qc is the temperature adjustment air flow rate measured by the flow meter 11.

Constants K3, S1 and A2 are stored in advance in the RAM 24. The constant A1 is preferably 1.2. Further, the constant A2 is preferably 1.4.

The blower control process by the CPU 21 will be described below. The blower control process is performed every time a clock pulse is sent from the clock pulse generating circuit 22. When a pulse is sent from the clock pulse generation circuit 22, the steam flow rate Qs detected by the steam flow rate detector 4 and the air flow rate detected by the air flow rate detector 11 are
Qc is captured and stored, for example, in a buffer (not shown).

Next, the airflow amount QF of the forced air blower 5 and the airflow amount QI of the suction air blower 14 are calculated (No. (6) and No.
(see formula (7)). And the motor 5a according to the air flow QF
Speed designation signal indicating the rotation speed and air flow rate
Speed designation signals representing the rotational speed of motor 14a according to QI are sent to drive control circuits 5b and 14b, respectively. With this, each motor 5a,
The rotational speed of the fan 14a is equal to the specified speed, and the amount of air blown (amount of suction) of each of the blowers 5 and 14 is made equal to QF and QI. The flow rate of air output from the blower 5 is controlled by the central controller 1.
After the furnace pressure is controlled to an appropriate value by the damper 7 controlled by the hopper 1a to
It is sent to 1c. Further, the exhaust gas discharge amount sucked by the blower 14 is controlled by a damper 16 controlled by a central controller 17 so that the furnace internal pressure becomes an appropriate value.

After that, based on the damper control signal, it is determined whether the dampers 7 and 16 are smaller than the reference opening degree DL (for example, 20%) for large air flow rate discrimination, and whether or not the dampers 7 and 16 are smaller than the reference opening degree DH (for example, 60%) for small air flow rate discrimination. It is determined whether the size is small or not. This judgment is made for each damper 7, 16, and the opening degree of each damper 7, 16 is smaller than the opening degree DL within the time until the next clock pulse is input from the clock pulse generation circuit 22. Narukama is repeated until the opening degree becomes larger than DH.

When the opening degree of the dampers 7 and 16 is determined to be smaller than the opening degree DL or larger than the opening degree DH, the state of being smaller than the opening degree DL and the state of being larger than the opening degree DH is constant. It is determined whether it continues for more than a certain amount of time. This fixed time is set, for example, to 1/3 to 1/2 of the clock pulse interval. If the opening degree continues to be smaller than DL for a certain period of time, it means that the amount of air blown is larger than necessary, so the damper 7
Blower 5 (or 14) corresponding to (or 16)
The speed designation signal is changed so that the amount of air blown is reduced by a fixed correction amount. In this case, motor 5a
(or 14a) is gradually reduced.

On the other hand, if the opening degree continues to be larger than DH for a certain period of time, there is a possibility that the airflow volume will be insufficient, so the airflow volume of the blower 5 (or 14) corresponding to the damper 7 (or 16) should be kept constant. The speed designation signal is changed so that it increases by the amount of correction. In this case, the rotational speed of the motor 5a (or 14a) is gradually increased. The amount of correction is determined in advance and stored in the RAM 24.

When executing blower control processing,
The next pulse is generated from the clock pulse generation circuit 22.
If it is sent to the CPU 21, the blower process is executed from the beginning without continuing the process currently being executed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the waste incineration apparatus, and FIG. 2 is a block diagram showing the electrical structure of the blower control device. 1... Incinerator, 2... Waste heat boiler, 4... Steam flow rate detector, 5... Forced blower, 7... Combustion air amount adjustment damper, 14... Induced blower, 16...
Furnace pressure adjustment damper, 20...Blower control device, 2
1...CPU, 22...Clock pulse generation circuit, 23...ROM, 24...RAM.

Claims (1)

[Claims] 1 Based on the detection signals of the furnace temperature detector and furnace pressure detector, the combustion air flow rate and exhaust gas exhaust flow rate are controlled by the damper so that the furnace temperature and furnace pressure become appropriate values, and the waste heat is The air flow rate of the forced air blower and the induced air blower is controlled based on the measured value of the generated steam flow rate of the boiler. It is determined based on the appropriate combustion air flow rate for the measured value of the generated steam flow rate calculated from the relationship with the combustion air flow rate. The value is the sum of the measured value of the air flow rate sent into the incinerator from the temperature adjustment blower to the appropriate combustion air flow rate for the measured value of the generated steam flow rate calculated from the relationship between the steam flow rate and the appropriate combustion air flow rate. A method for controlling the combustion air flow rate and exhaust gas discharge flow rate in an incinerator based on the following.