JP3859306B2 - Main combustion control method and control apparatus for surface melting furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a main combustion control method and control device for a surface melting furnace for burning and melting sludge such as sewage sludge.
[0002]
[Prior art]
As a conventional surface melting furnace, for example, there is a vertical rotary furnace having an internal / external double structure of an inner cylinder capable of moving up and down and a rotatable outer cylinder as shown in FIG.
[0003]
In this surface melting furnace, when the sludge 1 containing organic matter such as sewage sludge is introduced from the supply hopper 2 into the supply path 5 between the inner cylinder 3 and the outer cylinder 4, the sludge 1 in the supply path 5 becomes the outer cylinder. Combustion of the combustion device 9 in which the fuel 7 is burned by the main combustion air 8 in the main combustion chamber 6 inside the inner cylinder 3 while moving down in its own weight while being distributed uniformly in the circumferential direction by the rotation of 4. The inner peripheral surface is combusted and melted by self-combustion heat in which heat and sludge 1 are combusted by the main combustion air 8.
[0004]
The molten slag generated by the combustion and melting flows into the secondary combustion chamber 10 and the pit 11 continuously from the slag port 8 at the bottom of the furnace together with the combustion gas, solidifies, and is carried out by the slag conveyor 12 or the like.
[0005]
The unburned gas in the combustion gas flowing into the secondary combustion chamber 10 is combusted by the secondary combustion air 13 supplied into the chamber and the combustion heat of the auxiliary burner 15 in which the fuel 14 is combusted. After being discharged and treated by a smoke treatment device (not shown), it is released into the atmosphere.
[0006]
At this time, in order to continue stable melting, the temperature of the main combustion chamber is controlled, and as a means for that, the rotational speed of the outer cylinder 4 that affects the supply of the sludge 1 to the main combustion chamber 6 is adjusted. The temperature and supply amount of the fuel 7 and the main combustion air 8 are adjusted in a balanced manner.
[0007]
At this time, in order to increase the melt processing amount, it is better that the temperature of the main combustion chamber is high. Therefore, the main combustion air supply amount is usually increased as much as possible to promote the self-combustion of the sludge 1.
[0008]
[Problems to be solved by the invention]
By the way, in the above-described method, if the sludge 1 in the main combustion chamber 6 is melted on the entire surface and forms an inverted conical melting surface as shown, the main combustion air supply amount is made uniform. By increasing, self-combustion and melting of the sludge 1 can be promoted, and as a result, the amount of treatment increases.
[0009]
However, if a part of the surface sludge is melted and a part is unburned, the unburned sludge is floated by increasing the supply amount of the main combustion air, falls from the slag port 8, and is discharged into the secondary combustion chamber. Combustion may occur within 10. In such a case, in the main combustion chamber 6, the supplied main combustion air is not fully utilized for combustion, and not only does not lead to an increase in the processing amount, but also causes a harmful effect such as damage to the secondary combustion chamber 10.
[0010]
SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object of the present invention is to provide a main combustion control method and control device for a melting furnace that can burn and melt sludge over the entire surface and increase the throughput. .
[0011]
[Means for Solving the Problems]
In order to solve the above problem, the main combustion control method for a melting furnace according to the present invention is configured such that the sludge supplied between the inner cylinder and the outer cylinder arranged concentrically is moved below the inner cylinder by the rotation of the outer cylinder. Through the core, and in the main combustion chamber inside the inner cylinder, while supplying main combustion air, the sludge on the inner peripheral surface is burned and melted, and the resulting molten slag is discharged at the center of the bottom of the main combustion chamber. When discharging from the outlet, the temperature near the top of the main combustion chamber and the temperature near the lower end of the inner cylinder are measured at the same time, and the temperature difference value T0 between them is sequentially calculated. When the maximum value T0max and the minimum value T0min are calculated, the fluctuation value T0max -T0min between the calculated temperature difference values T0max and T0min is obtained, and when the calculated fluctuation value T0max -T0min exceeds the preset allowable temperature range Supply of main combustion air, which causes floating of unburned sludge By increasing the amount of sludge into the main combustion chamber by reducing the rotational speed of the outer cylinder according to the difference between the fluctuation value T0max-T0min and the allowable temperature range. Combustion / melting is performed with priority given to the formation of a stable melting surface.
[0012]
A main combustion control device for a melting furnace according to the present invention is a control device that performs the above-described main combustion control method for a melting furnace, and is connected to main combustion air supply means for supplying main combustion air into the main combustion chamber. A main combustion air supply amount adjusting means for adjusting the supply amount of the main combustion air, and a rotary drive device for an outer cylinder that forms a sludge supply path between the inner cylinder that forms the main combustion chamber. Rotational speed adjusting means for adjusting the rotational speed of the outer cylinder, top temperature detecting means for detecting the temperature near the top in the main combustion chamber, and inner cylinder lower end temperature detection for detecting the temperature near the lower end of the inner cylinder in the main combustion chamber And a control device electrically connected to the main combustion air supply amount adjusting means, the rotational speed adjusting means, the top temperature detecting means, and the inner cylinder lower end temperature detecting means. The top detected when the melt surface is formed The allowable temperature range corresponding to the fluctuation width of the temperature difference between the side temperature and the temperature near the bottom end of the inner cylinder is stored in advance, and the temperature value near the top measured at the same time by each of the top temperature detecting means and the inner cylinder lower end temperature detecting means. And the temperature difference T0 between the temperature near the lower end of the inner cylinder is sequentially calculated, the maximum value T0max and the minimum value T0min of the temperature difference value T0 within the predetermined time immediately before are calculated, and the calculated temperature difference values T0max and T0min The fluctuation value T0max−T0min is obtained, and when the obtained fluctuation value T0max−T0min exceeds the allowable temperature range, the main combustion air supply amount adjusting means causes the main combustion air that causes unburned sludge to float. Supply of sludge to the main combustion chamber by stopping the increase of the supply amount and lowering the rotation speed of the outer cylinder by the rotation speed adjusting means according to the difference between the fluctuation value T0max−T0min and the allowable temperature range. Reducing the amount Therefore, which is constituted to perform the priority combustion and melting the formation of a homogeneous melt surface.
[0013]
In the above configuration, the temperature near the top in the main combustion chamber represents the average temperature of the entire sludge melting surface, and the temperature near the lower end of the inner cylinder is the temperature detection of the melting surface of the sludge moving by the rotation of the outer cylinder. It is strongly influenced by local parts close to the sensor part. Therefore, the fact that the temperature fluctuation range in the vicinity of the local melt surface is larger than the average temperature means that the melt surface is not uniformly formed on the entire sludge surface, and there is an unburned portion. Means that
[0014]
For this reason, in the configuration described above, the increase in the supply amount of the main combustion air is stopped so that sludge floating does not occur, and the formation of a uniform molten surface is promoted. Prevent burning. In conjunction with this, a uniform molten surface is formed more quickly by reducing the rotational speed of the outer cylinder and reducing the amount of sludge supplied into the main combustion chamber. As a result, the throughput is temporarily reduced, but stable melting can be continued in the long term in automatic operation, and the throughput can be secured.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, the surface melting furnace for incinerating / melting sludge such as sewage sludge is similar to that described above with reference to FIG. A supply path 23 having a supply hopper 22 is formed between the inner cylinder 20 and the outer cylinder 21, and the main combustion chamber 24 is located inside the inner cylinder 20 communicating with the supply path 23. Is formed. A driving device 25 that rotates the outer cylinder 21 is provided outside the outer cylinder 21.
[0016]
A slag port 26 is formed at the center of the bottom of the main combustion chamber 24, and a secondary combustion chamber 27 for completely burning unburned gas flowing in from the main combustion chamber 24 is formed below the slag port 26. A slug pit (not shown) is provided below the bottom.
[0017]
A plurality of main combustion air supply ports 29 communicating with the blower 28 are formed in the central portion of the inner cylinder 20 forming the ceiling of the main combustion chamber 24, and a burner supplied with fuel from a fuel tank (not shown). 30 is provided.
[0018]
Inside the main combustion chamber 24, there are a sensor portion 31a of a top temperature detection device 31 for detecting the temperature in the vicinity of the top portion in the main combustion chamber 24, and a sensor portion of the inner cylinder lower end temperature detection device 32 for detecting the temperature in the vicinity of the inner cylinder lower end. 32a.
[0019]
Outside the furnace, a main combustion air supply amount adjusting device 34 for adjusting the main combustion air supply amount by the blower 28 via the line L1 and the control valve 33 is provided, and the rotational speed of the outer cylinder 21 by the drive device 25 is adjusted. A rotation speed adjusting device 35 for adjusting through the line L2 is provided, and the main combustion air supply amount adjusting device 34 and the rotation speed adjusting device 35 are electrically connected to the top temperature detecting device 31 by L3 and L4, respectively. Yes.
[0020]
A control device 36 is provided by electrically connecting the main combustion air supply amount adjusting device 34, the rotation speed adjusting device 35, the top temperature detecting device 31 and the inner cylinder lower end temperature detecting device 32 by lines L5, L6, L7, and L8. It has been.
[0021]
The control device 36 stores in advance an allowable temperature width (for example, 20 ° C.) corresponding to the fluctuation width of the temperature difference between the temperature near the top and the temperature near the lower end of the inner cylinder that is detected when the uniformity of the molten surface is appropriate. The temperature difference between the temperatures continuously measured by the top temperature detection device 31 and the inner cylinder lower end temperature detection device 32 is sequentially calculated, and the fluctuation width of the temperature difference within a predetermined time immediately before (for example, 1 hour). A value is calculated, the calculated fluctuation width value is compared with the allowable temperature range, and based on the result, the main combustion air supply amount adjusting device 34 and the rotation speed adjusting device 35 are controlled under predetermined conditions. ing.
[0022]
The operation of the above configuration will be described.
When sludge 37 such as sewage sludge is introduced into the supply path 23 between the inner cylinder 20 and the outer cylinder 21 from the supply hopper 22, the sludge 37 in the supply path 23 is rotated by the rotation of the outer cylinder 21 by the driving device 25. While being uniformly distributed in the direction, it descends its own weight, moves in the direction of the core through the lower part of the inner cylinder 20, and is supplied from the blower 28 through the main combustion air supply port 29 in the main combustion chamber 24 inside the inner cylinder 20. The sludge 37 on the inner peripheral surface side is combusted and melted by the main combustion air. The burner 30 is used only at the start of combustion.
[0023]
The molten slag generated by the combustion / melting flows together with the combustion gas continuously from the slag port 26 to the secondary combustion chamber 27 and pits (not shown), solidifies, and is carried out. Unburned gas in the combustion gas burns in the secondary combustion chamber 27 and is released into the atmosphere through a flue and a flue gas treatment device (not shown).
[0024]
At this time, the temperature near the top in the main combustion chamber 24 is detected by the sensor 31a of the top temperature detection device 31, and the temperature near the bottom of the inner cylinder is detected by the sensor 32a of the inner cylinder lower end temperature detection device 32. The temperature data near the top is transmitted to the main combustion air supply amount adjusting device 34 and the rotation speed adjusting device 35 through the lines L3 and L4, and based on this, the main combustion air supply amount adjusting device 34 is connected to the line L1, the control valve 33, The main combustion air supply amount is adjusted by the blower 28, and the rotation speed adjustment device 35 adjusts the rotation speed of the outer cylinder 21 by the line L2 and the drive device 25.
[0025]
At this time, the detected top vicinity temperature data and inner cylinder lower end vicinity temperature data are transmitted to the control device 36 through lines L7 and L8, respectively. Then, in the control device 36, the temperature difference value between the temperature near the top and the temperature near the lower end of the inner cylinder measured at the same time is sequentially calculated, and the fluctuation value of the temperature difference within the predetermined time immediately before is calculated. The amplitude value is compared with the allowable temperature range stored in advance.
[0026]
When the fluctuation value exceeds the allowable temperature range, it is determined that the uniformity of the melting surface is not appropriate, and the main combustion air supply amount adjusting device 34 causes the unburned sludge to float. The increase in the supply amount of the combustion air is prohibited, and the rotational speed of the outer cylinder 21 is reduced by the line L6 and the rotational speed adjusting device 35 according to the difference between the fluctuation value and the allowable temperature range, and the main combustion. The amount of sludge supplied into the chamber 24 is reduced, and combustion and melting are performed with priority given to the formation of a uniform melting surface.
[0027]
Thereafter, if the runout value obtained in the same manner is within the allowable temperature range, the operation returns to the normal operation.
By controlling the main combustion in this way, the throughput is temporarily reduced, but it is possible to realize stable continuation of melting and securing of the throughput in the long term in the automatic operation.
[0028]
【The invention's effect】
As described above, according to the present invention, the temperature near the top representing the average temperature of the entire melting surface and the temperature near the lower end of the inner cylinder that is strongly influenced by the local melting surface in the vicinity are measured. Compare the fluctuation width within a predetermined time of the difference between them, and when the fluctuation value is large, judge that unburned sludge exists on the surface, and operate the main combustion air supply amount and the outer cylinder rotation speed to make it uniform By promoting the formation of a stable melting surface, although the throughput is temporarily reduced, it is possible to realize stable continuation of melting and securing of the throughput in the long term in the automatic operation.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the configuration of a main combustion control device for a surface melting furnace in an embodiment of the present invention.
FIG. 2 is an explanatory view showing a schematic overall configuration of a conventional surface melting furnace capable of controlling the temperature by the apparatus of FIG. 1;
[Explanation of symbols]
20 inner cylinder
21 outer cylinder
23 Supply channel
24 Main combustion chamber
25 Drive unit
28 Blower
31 Top temperature detector
32 Inner cylinder lower end temperature detector
34 Main combustion air supply control device
35 Rotational speed adjustment device
36 Control unit
37 Sludge

Claims (2)

The sludge supplied between the inner cylinder and the outer cylinder arranged concentrically is moved in the direction of the core through the lower part of the inner cylinder by the rotation of the outer cylinder, and in the main combustion chamber inside the inner cylinder, While supplying combustion air, the sludge on the inner peripheral surface is combusted and melted, and when the generated molten slag is discharged from the discharge port at the center of the bottom of the main combustion chamber, the temperature near the top of the main combustion chamber and the temperature near the bottom of the inner cylinder Are measured at the same time to sequentially calculate the temperature difference value T0 between the two, calculate the maximum value T0max and the minimum value T0min of the temperature difference value T0 within the immediately preceding predetermined time, and calculate the calculated temperature difference values T0max and T0min The fluctuation value T0max -T0min is calculated, and when the calculated fluctuation value T0max -T0min exceeds the preset allowable temperature range, the increase in the supply amount of the main combustion air that causes the unburned sludge to float is stopped. And the deflection value T0max−T0min Combustion and melting giving priority to the formation of a uniform melting surface by reducing the amount of sludge supplied to the main combustion chamber by reducing the rotational speed of the outer cylinder according to the difference between the allowable temperature range and the allowable temperature range A main combustion control method for a surface melting furnace. A control apparatus for performing a main combustion control method for a surface melting furnace according to claim 1, wherein the main combustion air supply means is connected to a main combustion air supply means for supplying main combustion air into the main combustion chamber. A main combustion air supply amount adjusting means for adjusting the amount and an inner cylinder forming a main combustion chamber are connected to a rotation driving device of an outer cylinder that forms a sludge supply path, and the rotation speed of the outer cylinder is set. A rotation speed adjusting means for adjusting; a top temperature detecting means for detecting a temperature near the top in the main combustion chamber; and an inner cylinder lower end temperature detecting means for detecting a temperature near the lower end of the inner cylinder in the main combustion chamber, and the main combustion. A control device electrically connected to the air supply amount adjusting means, the rotation speed adjusting means, the top temperature detecting means, and the inner cylinder lower end temperature detecting means is provided, which is detected when a uniform molten surface is formed. The temperature near the top and the temperature near the bottom of the inner cylinder The allowable temperature range corresponding to the fluctuation width of the temperature difference is stored in advance, and the temperature between the top vicinity temperature value and the inner cylinder lower end temperature value measured at the same time from the top temperature detection means and the inner cylinder lower end temperature detection means, respectively. The difference T0 is sequentially calculated, the maximum value T0max and the minimum value T0min of the temperature difference value T0 within the immediately preceding predetermined time are calculated, and the fluctuation value T0max-T0min between the calculated temperature difference values T0max and T0min is obtained and obtained. When the fluctuation range value T0max−T0min exceeds the allowable temperature range, the main combustion air supply amount adjusting means stops the increase in the supply amount of the main combustion air that causes the unburned sludge to float, and Uniform melting by reducing the amount of sludge supplied to the main combustion chamber by reducing the rotational speed of the outer cylinder by the rotational speed adjusting means according to the difference between the swing width value T0max-T0min and the allowable temperature range. surface A main combustion control device for a surface melting furnace, characterized in that combustion / melting is performed with priority given to formation of the surface melting furnace.

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