JP2000179821A - Method and apparatus for controlling hearth temperature of fluidized bed incinerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate an incompletely burned state in a furnace body. SOLUTION: A water spraying nozzle 12 is mounted at a sidewall of a body 2 of a fluidized bed incinerating furnace 1 having a lower hearth 3 and its upper side secondary combustion chamber 7, and a water feed tube 13 provided with a flow regulating valve 19 is connected. A flow regulating valve controller 20 for controlling a valve travel of the valve 19 according to a difference between a hearth temperature T obtained by averaging detected values of a plurality of temperature detectors 16 by a calculator 21 and a set temperature T0 of a temperature setter 17 when the temperature T exceeds the temperature T0 is provided. Thus, the travel of the valve 19 is changed to continuously increase or decrease an amount of water 14 sprayed from a water spraying nozzle 12 to the hearth 3 to smoothly temperature change the chamber 7 in the case of controlling the temperature T.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a hearth temperature of a fluidized bed incinerator used for incinerating waste such as municipal waste.

[0002]

2. Description of the Related Art A fluidized bed incinerator 1 used for incinerating waste such as municipal solid waste is shown in FIG.
At the lower part of the furnace body 2, sand 4 as a combustion medium is filled to provide a hearth 3 as a fluidized bed, and a plurality of diffuser tubes 5 are arranged in the furnace hearth 3 in a horizontal state. By blowing air for primary combustion into the hearth 3 through the trachea 5, the hearth 3 is fluidized to cause primary combustion of waste in the hearth 3, and furthermore, the combustion gas generated in the primary combustion Is burned in the secondary combustion chamber 7 above the hearth 3 by the secondary combustion air supplied through the air supply pipe 6.
8 is a dust supply device for supplying waste into the furnace body 2, 9
Is an exhaust gas outlet provided at the top of the furnace body 2, 10 is an incombustible substance discharge device provided at the bottom of the furnace body 2, 11 is the sand 4 separated from the incombustible substance after being dropped and discharged together with the incombustible substance. It is a sand circulation conveyor for returning to the hearth 3 inside.

Further, in the fluidized bed incinerator 1, the temperature of the hearth 3 is required to be maintained within an appropriate temperature range (for example, 640 ± 15 ° C.). A water spray nozzle 12 for spraying water 14 fed through a water feed pipe 13 provided with an electromagnetic valve 15 toward the hearth 3 is provided on a side wall of the furnace body 2 located therein. The detected hearth temperature T is compared with a set temperature T ₀ previously set to 640 ° C. or the like in the temperature setting unit 17, and when the hearth temperature T becomes higher than the set temperature T ₀ , the electromagnetic valve controller By turning on the electromagnetic valve 15 in response to a command from 18, water 14 is sprayed from the water spray nozzle 12 toward the hearth 3, thereby cooling the hearth 3. The water spray nozzle 12 prevents thermal damage by blowing out cooling air when the water 14 is not sprayed.

[0004]

However, in the prior art,
Since the CO concentration in the exhaust gas was not considered to be a problem, an electromagnetic valve 15 was provided in the water supply pipe 13 to turn the CO on.
In the configuration in which the OFF is switched, in the hearth temperature control method of the above-mentioned conventional fluidized bed incinerator, the spray of the water 14 from the water spray nozzle 12 is performed by the ON-OF of the electromagnetic valve 15.
It is intermittent due to the switching of F. Therefore, the change between the spray state of the water 14 and the spray stop state is a disturbance factor for the combustion state in the furnace body 2, and particularly, the moment the water 14 is sprayed from the water spray nozzle 12
In this case, there is a problem that an incomplete combustion state occurs in the secondary combustion chamber 7 and the generation amount of harmful gas such as carbon monoxide may be increased. In order to take measures against dioxin in recent years, it is necessary to eliminate the above incomplete combustion state.
N, OFF could not control.

[0005] Therefore, the present invention provides a hearth of a fluidized bed incinerator capable of controlling the temperature of the hearth without causing an incomplete combustion state that may increase the generation amount of harmful gas. It is intended to provide a temperature control method and device.

[0006]

According to the present invention, in order to solve the above-mentioned problems, water is continuously sprayed onto a hearth of a fluidized bed incinerator using a hearth as a fluidized bed by a water spray nozzle. And a hearth temperature control method for a fluidized bed incinerator, wherein the hearth temperature is controlled by continuously adjusting the spray amount of water based on the hearth temperature detection signal. Temperature detector for detecting the temperature of the hearth of a fluidized bed incinerator having a fluidized bed, a water spray nozzle assembled to a furnace body so that water can be sprayed toward the hearth, and the water spray nozzle A water supply pipe connected to the water supply pipe, a flow control valve provided in the middle of the water supply pipe, a hearth temperature based on a detection signal from the temperature detector and a set temperature, and according to the difference, A flow control valve controller for continuously sending an opening control command to the flow control valve. The furnace bed temperature control system for a fluidized bed incinerator.

When the hearth temperature rises above the set temperature during operation of the fluidized bed incinerator, an opening control command is continuously sent from the flow control valve controller to the flow control valve based on the temperature, and the water spray By adjusting the amount of water sprayed from the nozzle to the hearth, the hearth temperature is maintained near the set temperature.

An air supply pipe provided with an electromagnetic valve is connected to the water supply pipe at a position downstream of the flow control valve, and an opening control command from the flow control valve controller is monitored to control the flow rate. By providing an electromagnetic valve controller that turns on the electromagnetic valve when the opening degree of the control valve becomes equal to or less than a predetermined value, the amount of water supplied to the water spray nozzle is reduced. When the water does not become mist, the solenoid valve is turned on by a command from the solenoid valve controller, so that water is dripped from the water spray nozzle by introducing air into the water supply pipe. Can be prevented.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a method and an apparatus for controlling a hearth temperature of a fluidized bed incinerator according to the present invention.
In the fluidized bed incinerator 1 in which the inner hearth 3 is a fluidized bed,
As shown in FIG. 2, the water spray nozzle 12 is assembled to the furnace body 2, and the water feed pipe 1 connected to the water spray nozzle 12 is connected.
3, a flow control valve 19 is provided, and the flow control valve 1
9 by controlling the opening degree of the flow control valve 19 to be continuously changed by sending the opening degree control command C ₁ to the amount of water 14 sprayed from the water spray nozzle 12 through the water feed pipe 13. A flow control valve controller 20 for continuously changing the flow rate is provided. The flow control valve controller 20 includes the hearth 3
The hearth temperature T obtained by averaging the detected values from the temperature detectors 16 installed so as to be able to detect the temperatures at a plurality of locations (two locations in the figure) by the computing unit 21 and the temperature setting unit 17 Set temperature (for example, 640 ° C.) T _O set in advance
Is input and a comparison operation is performed, and the hearth temperature T becomes the set temperature T
_{When the value} exceeds _O , the degree of opening of the flow control valve 19 can be controlled so as to correspond to the magnitude of the difference. During the operation of the fluidized-bed incinerator 1, the flow control valve 19 is kept in a closed state so as not to be in a fully closed state.
4 is controlled to flow.

Further, an air supply pipe 22 connected to a pressurized air supply device (not shown) is connected to a position downstream of the flow control valve 19 of the water supply pipe 13 so as to connect the air supply pipe. An electromagnetic valve 23 and a check valve 26 are provided in the middle of 22 and the opening control command C ₁ sent from the flow control valve controller 20 to the flow control valve 19 is constantly monitored to open the flow control valve 19. Degree 2
When 0% opening control command C ₁ as to become less is issued, provided the solenoid valve controller 24 for sending the ON command C ₂ to the solenoid valve 23, is fed to the water spray nozzle 12 Water 1
In the case where the flow rate of 4 is restricted by the flow rate control valve 19 to a small value of 20% or less, the pressurized air 25 generated by the pressurized air supply device is passed through the air supply pipe 22 to the water supply pipe. 1
3 and can be sprayed from the water spray nozzle 12 together with the water 14.

The same components as those shown in FIG. 2 are denoted by the same reference numerals.

When the fluidized bed incinerator 1 is operated, the temperature of each part detected by each temperature detector 16 is averaged by the calculator 21 to obtain the hearth temperature. The set temperature T _O set in the section 17 is compared with the flow control valve controller 20, and a difference between the hearth temperature T and the set temperature T ₀ is such that the hearth temperature T exceeds the set temperature T _O. If so, the opening control command is given from the flow control valve controller 20 to the flow control valve 19 in accordance with the difference between the hearth temperature T and the set temperature T _O , the opening is controlled, and the water feed pipe is controlled. The flow rate of water 14 sent to water spray nozzle 12 through 13 is adjusted, and the amount of water 14 sprayed from water spray nozzle 12 toward hearth 3 is appropriately increased or decreased. As a result, the hearth temperature T is controlled so that there is no difference from the set temperature T _O.

In this case, for example, the hearth temperature T is set to a set temperature.
Degree T_OIf higher than, from the flow control valve controller 20
Opening control command C₁And the opening of the flow control valve 19 is large.
So that the water spray nozzle 12
The amount of water 14 sprayed towards 3 will be increased.
The hearth temperature T is lowered, and the hearth temperature T and the set temperature T
_OOf the temperature detector 1
The hearth temperature T detected in Step 6 is averaged by the arithmetic unit 21.
Set temperature T₀And the hearth temperature T
Set temperature T₀, The opening of the flow control valve 19 becomes
It is continuously controlled so that it gradually becomes smaller,
Water 14 sent to the water spray nozzle 12 and sprayed on the hearth 3
Is adjusted so as to gradually decrease, and the hearth temperature T
Set temperature T _OIt will be held near.

As described above, since the temperature T of the hearth 3 can be controlled by continuously adjusting the amount of the water 14 sprayed from the water spray nozzle 12 in accordance with the temperature T of the hearth 3, The temperature change in the secondary combustion chamber 7 when increasing or decreasing the amount of spray can be moderated, the combustion state in the secondary combustion chamber 7 can be stably maintained, and the electromagnetic valve
N, secondary combustion chamber 7 as in conventional hearth temperature control to be turned off
It is possible to eliminate the occurrence of an incomplete combustion state due to a rapid temperature drop in the inside, and thus to suppress the generation amount of harmful gases such as carbon monoxide.

In the state where the spray amount of the water 14 is continuously controlled as described above, the hearth temperature T becomes equal to the set temperature T.
_When the flow rate of the water is reduced so that there is no difference from ₀ , when a small amount of water flows such that the opening degree of the flow control valve 19 becomes 20% or less, the electromagnetic valve controller 24 controls the air flow. The electromagnetic valve 23 provided on the feed pipe 22 is turned on,
Pressurized air 25 guided through the air supply pipe 22 is supplied into the water supply pipe 13, and is supplied to the water spray nozzle 12 together with the water 14.
To be ejected from the water spray nozzle 12 together with the water 14. Therefore, the difference between the hearth temperature T and the set temperature T _O is reduced, and the water 1
It is possible to prevent the water 14 from dropping from the water spray nozzle 12 due to a shortage of the water pressure due to a decrease in the feed amount of 4.

Although the present invention is not limited to the above embodiment, the water spray nozzle 12 is shown to be provided at one place on the side wall of the furnace body 2, but the place and number of the water spray nozzles 12 can be arbitrarily determined. The case where the temperature detector 16 is installed at two places on the hearth 3 has been described. However, the number and location of the temperature detectors 16 can be arbitrarily selected. Although the case where the ON operation is performed when the degree becomes 20% or less is shown, it is not limited to this.
In addition, it goes without saying that various changes can be made without departing from the spirit of the present invention.

[0018]

As described above, according to the present invention, water is continuously sprayed to the hearth of a fluidized bed incinerator using a hearth as a fluidized bed by a water spray nozzle. A method of controlling the temperature of the hearth of a fluidized bed incinerator in which the spray amount of water is continuously adjusted based on the temperature detection signal of the hearth to control the temperature of the hearth, A temperature detector for detecting the temperature of the hearth of the fluidized bed incinerator, a water spray nozzle attached to the furnace body so that water can be sprayed toward the hearth, and water connected to the water spray nozzle. A feed pipe,
The flow rate control valve provided in the middle of the water supply pipe is compared with the hearth temperature based on the detection signal from the temperature detector and the set temperature, and the flow rate control valve is continuously opened according to the difference. Flow rate control valve controller to send a degree control command, because it is a hearth temperature control device of a fluidized bed incinerator having a configuration comprising a
By continuously controlling the opening of the flow control valve by the flow control valve controller, the amount of water sprayed from the water spray nozzle can be continuously changed, and the furnace for increasing or decreasing the water spray amount The temperature change in the body can be moderated, and the occurrence of an incomplete combustion state due to a rapid temperature drop in the furnace body such as the conventional hearth temperature control can be eliminated. It has an excellent effect that the hearth temperature can be controlled without increasing the amount of harmful gas generated in the furnace, and an electromagnetic valve is installed at a position downstream of the flow control valve of the water supply pipe. The solenoid valve is turned on when the air supply pipe provided is connected and the opening control command from the flow control valve controller is monitored and the opening of the flow control valve falls below a predetermined value.
When the water supply amount to the water spray nozzle is reduced and the water pressure is reduced by adopting the configuration including the electromagnetic valve controller configured to send air together with water to the water spray nozzle Therefore, it is possible to prevent water from dripping from the water spray nozzle.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a method and an apparatus for controlling a hearth temperature of a fluidized bed incinerator according to the present invention.

FIG. 2 is a schematic diagram showing an example of a conventional fluidized bed incinerator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluid bed incinerator 2 Furnace body 3 Furnace floor 12 Water spray nozzle 13 Water supply pipe 14 Water 16 Temperature detector 19 Flow control valve 20 Flow control valve controller 22 Air supply pipe 23 Solenoid valve 24 Solenoid valve controller

Claims (3)

[Claims] The present invention is characterized in that water is continuously sprayed to a hearth of a fluidized bed incinerator using a hearth as a fluidized bed by a water spray nozzle, and water is sprayed on the basis of a temperature detection signal of the hearth. A method for controlling a hearth temperature of a fluidized-bed incinerator, wherein the hearth temperature is controlled by continuously adjusting a spray amount. 2. A temperature detector for detecting the temperature of the hearth of a fluidized bed incinerator having a hearth as a fluidized bed, and a water spray attached to the furnace body so that water can be sprayed toward the hearth. A nozzle, a water feed pipe connected to the water spray nozzle, a flow control valve provided in the middle of the water feed pipe, and a comparison between a hearth temperature and a set temperature based on a detection signal from the temperature detector. And a flow control valve controller for continuously sending an opening control command to the flow control valve according to the difference. . 3. An air supply pipe provided with an electromagnetic valve is connected to a position downstream of the flow control valve of the water supply pipe, and an opening control command from the flow control valve controller is monitored to control the flow rate. 3. The apparatus according to claim 2, further comprising an electromagnetic valve controller configured to turn on the electromagnetic valve when the opening of the control valve is equal to or less than a predetermined value.