JP3366200B2 - Combustion control method in incinerator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling combustion in an incinerator, and more particularly, to waste (general waste such as municipal waste from homes and offices, waste Including combustible materials such as plastic, car shredder dust, waste office equipment, electronic equipment, industrial waste such as chemical products)
The present invention relates to a method for controlling combustion in an incinerator suitable for incineration of incinerators. 2. Description of the Related Art Waste is introduced into an incinerator as one of the treatment apparatuses for waste such as municipal solid waste such as general waste, industrial waste such as waste plastic, and the like, including combustible waste. And
In general, a method is employed in which combustion air is sent in and incinerated, exhausted as exhaust gas, and incombustibles are collected. As combustion air, primary air for burning waste and incomplete combustion also occur due to the primary air to reduce CO2
Is generated, secondary air is supplied to completely combust this. The incinerator is, for example, a fluidized bed incinerator with a fast burning rate, in which air is blown into the fluidized sand that accumulates on the hearth, causing the sand to flow so that the incombustibles move downward with the sand. It is dropped and the combustion products are discharged as exhaust gas. A reference example of control at the time of shutdown for stopping the operation of the incinerator will be described with reference to FIG. When shutting down the incinerator, first, the operation of supplying waste such as refuse is stopped, and the input of waste to the incinerator is stopped. Next, the secondary air and the primary air are stopped in two stages as shown in the figure. In order to burn the waste remaining in the furnace even after the refuse is stopped, the primary air is blown off with a slight delay. Under such control, the temperature of the exhaust gas from the furnace is lowered from about 850 ° C. in the normal state, and the O ₂ concentration is increased from 13% in the normal state to 18% in the fall. However, the CO concentration was 10 ppm or less during normal combustion, but rose temporarily to 500 ppm or more at the time of shutdown, indicating that incomplete combustion has occurred. This is presumed to be because in an incinerator with a fast burning rate such as a fluidized bed incinerator, the shutdown during shutdown is completed in only a few minutes, but in any case, this CO peak is eliminated. To prevent the furnace temperature from dropping,
Shutdown is performed using auxiliary fuel such as kerosene, which is inefficient in terms of economics and maintenance.
There was a problem that an increase in the O concentration was not preferable. An object of the present invention is to solve the above-mentioned problems. When the incinerator is shut down, the supply of waste is stopped, and the amount of combustion air is controlled to prevent incomplete combustion. An object of the present invention is to provide a combustion control method in an incinerator that enables stable shutdown without increasing the CO concentration. [0005] The above-mentioned problems have been solved as follows. The present invention, waste such as dust through the waste supply means was charged into the fluidized bed incinerator, one into said incinerator
Fluidized bed incineration in which secondary air and secondary air are supplied for incineration
When shutting down the furnace , first stop the supply of the waste ,
Then, the blowing of the secondary air and the primary air is stopped.
Before, so as to hold the temperature inside the incinerator, the
A gradually decreasing section A gradually decreasing the supply of the secondary air and before
Set the gradually decreasing section B to gradually reduce the primary air supply.
After the elapse of each gradual section, the secondary air
Then, while stopping the blowing of the primary air,
The gradually decreasing gradient of the gradually decreasing section A of the air is determined by the decreasing section of the secondary air.
It is characterized in that the control is performed more gently than the gradually decreasing gradient of the interval B. By such control, incomplete combustion of the waste remaining in the furnace is prevented, and the shutdown of the incinerator without increasing the CO concentration can be realized. That is, by preventing the generation of CO by the secondary air and effectively performing the primary combustion of the waste remaining in the furnace, a stable shutdown can be realized.
Therefore, in a fluidized bed incinerator that can be shut down in a short time, incomplete combustion during shutdown is prevented, and CO
Since the increase in the concentration can be prevented, no means such as auxiliary fuel is required, which is extremely effective for labor saving. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram illustrating an embodiment of the combustion control method according to the present invention. As shown in FIG. 1, the incinerator 1 uses a fluidized bed incinerator as an incinerator with a high burning rate. A steeply inclined pan-type conveyer 2 for quantitatively placing waste on a pan and transporting the waste by steeply inclined, and a flow of air unnecessary for combustion and from the inside of the incinerator to a waste introduction path to the incinerator 1. In order to prevent flashback, an air sealing device 3 for quantitatively collecting wastes conveyed from the conveyor 2 in a compartment defined by an impeller and feeding the waste into the incinerator 1 is provided. . The incinerator 1 also includes a push (primary) air valve 4, a push (primary) air pipe 6 having a push (primary) blower 5, a secondary air valve 7, and a secondary blower 8. The secondary air piping 9 is connected to each other. In the present embodiment, the temperature sensor 1 is disposed at an arbitrary position in the incinerator 1.
0, the pushing air valve 4 and the secondary air valve 7
1 are connected. With this configuration, when shutting down the incinerator, after the introduction of waste is stopped, the temperature sensor is monitored, the temperature in the furnace is maintained within a certain range, incomplete combustion is prevented, and a rise in the CO concentration is prevented. To prevent this, the supply of primary and secondary air was controlled. In the present embodiment, the exhaust gas outlet temperature detecting unit 12 is connected to the operation motor of the conveyor 2 and the motor for rotating the impeller of the air seal device 3 so that the supply of waste can be controlled by the exhaust gas outlet temperature. Has become. Next, an example of control when the incinerator is shut down by the method of the present invention will be described with reference to FIG. As shown in FIG. 2, the supply of the waste is first stopped. Next, before stopping the blowing of the secondary air and the primary air, the furnace temperature is maintained by the furnace temperature sensor 10, so that the supply of the secondary air is gradually reduced, and the primary air is gradually reduced. Similarly, a gradually decreasing section B was set, and after the elapse of each gradually decreasing section, control was performed such that the blowing of the secondary air and then the primary air was stopped. In order to burn the waste remaining in the furnace, the gradual gradient of the primary air is made gentler than that of the secondary air. By performing such control,
Compared with the reference example of FIG. 3, no increase in the CO concentration was observed. Also, the temperature of the exhaust gas from the furnace gradually decreases, and
_{2 is} also rising. Next, a fluidized bed waste incinerator to which the combustion control method of the present invention is applied will be described with reference to FIG. FIG. 4 is a configuration diagram illustrating an example of a fluidized bed waste incineration apparatus. As shown in FIG. 4, the waste 31 temporarily stays in the pit 32, and is appropriately conveyed to the waste feeder 34 by the crane 33. A screw feeder is used for the waste feeder 34, and has the following two main functions. It has a function to break bags containing waste, or to crush or cut out waste, and a function to check and discharge unsuitable materials. The former function is a function of repeatedly compressing and loosening bag waste or the like between screws or between a screw and a casing, and cutting out waste while crushing. The latter function restricts the injection of non-combustible materials of a certain size or more, and also turns the screw forward and reverse to loosen waste such as garbage, and removes large-sized waste and waste with strong crushing resistance. Is a function of reversing and discharging from the rear outlet. [0010] The waste which has been roughly crushed after passing through the waste feeder 34 is sent to a metering machine 35. The metering machine 35 adjusts the amount of waste to be supplied to the incinerator and constantly supplies a constant amount thereof in order to perform stable combustion in the incinerator. In the present embodiment, a steeply inclined pan-type conveyor is used, and the waste in the hopper is transported on a pan of the conveyor. The waste conveyed from the metering machine 35 is supplied to the incinerator 37 via the air seal device 36. The air seal device 36 is provided in the waste supply part of the combustion furnace 37, maintains airtightness in the incinerator, and supplies air unnecessary for combustion when injecting waste into the incinerator. This is to prevent flashback. In the present embodiment, waste is collected by a rotating impeller and is sequentially supplied into an incinerator having an airtight structure. The incinerator 37 is a fluidized bed type incinerator, in which a forced sand 39 is blown into a fluidized sand (fluid medium) 38 deposited on the hearth to make the fluid flow so as to make the combustion temperature in the furnace constant. Or the incombustibles in the waste 31 are dropped together with the flowing sand 38. The air 39 pushed in to flow the sand 38 is also primary air for primary combustion. The incomplete combustion by the primary air 39 is completely burned by the secondary air 40 to be discharged as clean exhaust gas 41. In the present embodiment, as shown in FIG. 1, a temperature sensor is provided in the furnace, and the supply amounts of the primary air and the secondary air are controlled according to the furnace temperature. The combustion is adjusted by burning the fuel 43 with the auxiliary heat burner 42. Generally, heavy oil is used as the fuel. Also, the combustion temperature can be controlled by the manner of distribution of the primary air 39 and the secondary air 40. Usually, fluidized bed incinerator 37
The waste 31 put into the furnace is dried and completely incinerated in a short time by the fluidized sand 38 heated to 600 to 700 ° C. The temperature of the exhaust gas at the outlet of the fluidized bed incinerator 37 is maintained at 800 to 900 ° C. The incombustibles that cannot be burned in the incinerator are discharged out of the incinerator by the fluidized medium discharger 44 together with the fluidized sand.
It is separated from the fluidized sand by the fluidized media classifier 45 and the iron 47 and other noncombustibles (non-ferrous incombustibles 4) by the magnetic separator 46.
8) and are collected from the iron bunker 49 and the noncombustible bunker 50, respectively. Fluid medium classifier 45
The fluidized sand sieved in is returned to the combustion furnace 37 by the fluidized-medium transporter 51. The waste sewage 52 accumulated in the pits 32 is sprayed into the incinerator 37 via a filtration spray pump 53 and subjected to high-temperature oxidation treatment. Further, the odor of the waste 31 from the pit 32 or the like is sucked into the secondary air 40, the primary air (push air) 39 or the like as combustion air, supplied to the furnace, decomposed by high-temperature oxidative decomposition, and deodorized. . Pit 32
Is provided with a waste input door 54. Further, sludge 55 and the like can be put into the incinerator 37 for incineration. In such a fluidized bed type waste treatment apparatus, when the incinerator is shut down, as shown in FIG. 1, the control for gradually decreasing the supply amounts of the secondary and primary air while maintaining the furnace temperature is performed. In the fluidized bed incinerator, the operation of which can be stopped within a short period of time, incomplete combustion is prevented, and a rise in the CO concentration can be prevented. This is extremely effective for labor saving. As described above, the present invention has been described in detail with reference to the illustrated embodiments. However, the present invention is not limited to only those embodiments, and various modifications can be made without departing from the spirit of the present invention.
It goes without saying that a wide variety of modifications can be made. As described above, according to the combustion control method of the present invention, when the incinerator is shut down, the supply of waste air and the supply of combustion air are controlled at the same time as the supply of waste air is controlled. It is possible to prevent complete combustion and perform a stable shutdown without increasing the CO concentration. Therefore, there is an excellent effect that the conventional combustion with the auxiliary fuel is not required.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram for explaining an embodiment of a combustion control method according to the present invention. FIG. 2 is a diagram for explaining one control example of the present invention. FIG. 3 is a diagram illustrating a reference example of control according to the present invention. FIG. 4 is a configuration diagram showing an embodiment of a fluidized bed waste incinerator to which the present invention is applied. [Description of Signs] 1 Incinerator 2 Bread conveyor 3 Air seal device 4 Push-in (primary) air valve 5 Push-in (primary) blower 6 Push-in (primary) air pipe 7 Secondary air valve 8 Secondary blower 9 Secondary air pipe 10 Furnace temperature sensor 11 Controller 12 Exhaust gas outlet temperature detector 31 Waste 32 Pit 33 Crane 34 Waste feeder 35 Metering machine (steeply inclined conveyor) 36 Air seal device 37 Incinerator 38 Fluid sand (fluid medium) 39 Pushing Air (primary air) 40 Secondary air 41 Exhaust gas 42 Heating burner 43 Fuel 44 Fluid medium discharger 45 Fluid medium classifier 46 Magnetic separator 47 Iron 48 Non-ferrous non-combustible material 49 Iron bunker 50 Non-combustible material bunker 51 Fluid media carrier 52 Waste Waste water 53 Filtration spray pump 54 Waste input door 55 Sludge A, B Gradual reduction section

Continuation of front page (56) References JP-A-5-296430 (JP, A) JP-A-60-105808 (JP, A) JP-A-55-20359 (JP, A) JP-A-59-197716 (JP) , A) JP-A-8-145339 (JP, A) JP-A-61-38312 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23G 5/50 F23G 5/30 F23C 10/28

Claims (1)

(57) [Claims] [Claim 1] Waste such as garbage is put into a fluidized bed incinerator through a waste supply means, and primary air is introduced into the incinerator.
And when the fluidized bed incinerator for incineration by supplying secondary air is shut down, first, supply of the waste is stopped, and then
Before stopping the blowing of the secondary air and the primary air,
The secondary space is maintained by maintaining the temperature in the incinerator.
A gradually decreasing section A for gradually reducing the supply of air and the primary
Set the gradual decrease section B to gradually reduce the air supply.
After the elapse of each decreasing section, the secondary air and then the
While stopping the primary air blow, the primary air
The gradually decreasing gradient of the decreasing section A is set to the gradually decreasing section B of the secondary air.
A method for controlling combustion in an incinerator , wherein the control is performed more gently than the gradient .