JPH0247649B2 - ROOTARIKIRUNNIOKERUNENSHOHAIGASUOMOCHIITANENSHOSEIGYOHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a combustion control method using combustion exhaust gas in a rotary kiln.

Conventional Technology Waste input into a rotary kiln passes through a drying zone, a pyrolysis/gasification zone, a flaming combustion zone, and an arbor combustion zone, and then completes its combustion.

Problems to be Solved by the Invention By the way, according to the above combustion, due to differences in the properties of the waste (moisture content, calorific value, ignition temperature, etc.),
The time required for the above processes varies widely. In particular, waste material changes rapidly in its properties, so depending on the property changes, the drying zone in the rotary kiln,
Although the lengths of the pyrolysis/gasification zone, flaming combustion zone, and stoking combustion zone vary, it has been impossible to stably control each zone due to the structure of the rotary kiln. For this reason, in the case of high calorific value waste with good ignitability, rapid flaming combustion cannot be controlled after being put into the kiln, causing damage to the inner wall of the kiln and high concentration of NOx.
There was a problem that occurred. On the other hand, in the case of low calorific value waste with poor ignitability, the length of the drying zone and pyrolysis/gasification zone from the time it is introduced into the kiln to the start of flaming combustion is long and unstable, so There was a problem that combustion could not be obtained. All of these problems are due to the fact that most of the heat required for the drying zone of hydrous fuel and the pyrolysis/gasification zone depends on heat radiation from the flame due to flaming combustion, and that the intensity of this flame radiation is usually This is due to the fact that the previous combustion control method was unable to control the combustion. In other words, if it is possible to artificially control the distribution of pyrolysis gas concentration, oxygen concentration, and combustion reaction zone temperature within the furnace wall, which determine the flame radiation intensity,
This also makes it possible to control each zone within the zone.

Conventionally, methods have been used for this type of purpose by changing the amount of combustion air and the position at which it is introduced, but because the oxygen concentration in the air is as high as approximately 21%,
The combustion reaction between the pyrolysis gas and the incoming air was difficult to control, and therefore it was also impossible to control the flame radiation intensity.

Means for Solving the Problem In order to solve the above problem, the combustion control method in a rotary kiln of the present invention has a cylindrical furnace wall, and waste is transferred from one of the open ends of the furnace wall to the other. In a rotary kiln, in which a drying zone, a pyrolysis/gasification zone, a flaming combustion zone, and a stoking combustion zone are formed in the order of the waste transfer route, primary air for combustion is supplied from the open end of one of the furnace walls. At the same time, the flue gas is supplied from the middle part of the furnace wall, and the amount of this flue gas supplied is controlled by the temperature inside the furnace wall, and the flue gas is supplied to the middle part of the furnace wall, that is, the flaming combustion zone. This prevents temperature rise in the flaming combustion zone and provides stable combustion.

Embodiment An embodiment of the present invention will be described below with reference to FIG. Reference numeral 1 denotes a cylindrical furnace wall of a cocurrent rotary kiln, which is rotatably supported. 2 is this furnace wall 1
A loading hood installed on one open end side of the
A waste input hopper 3 is inserted in the middle part, and an auxiliary fuel injection nozzle 4 is inserted in the lower part.
is provided. Reference numeral 5 denotes an exhaust hood provided on the other open end side of the furnace wall 1, with an incineration residue exhaust port 6 formed at its lower part and a combustion gas exhaust port 7 formed at its upper part. 8 and 9 are first and second annular air supply chambers provided at intermediate longitudinal positions of the furnace wall 1 and along the outer peripheral surface of the furnace wall 1;
It communicates with the inside of the furnace wall 1 via a plurality of air intake pipes 11 each having a flow rate regulating valve 10.
12 is an air supply line that supplies primary air for combustion and secondary air for combustion into the furnace wall 1;
3, and three air supply branch pipes 12B branched from this main air supply pipe 12A and each having a damper 14.
12C and 12D are branched, and one of them is 1
2B is connected to the charging hopper 3, and the remaining two 12C and 12D are connected to the first and second annular air supply chambers 8 and 9, respectively. 15 is an exhaust gas supply line that supplies combustion exhaust gas into the furnace wall 1;
Exhaust gas supply main pipe 15A and this exhaust gas supply main pipe 1
5A and a damper 16 respectively.
each having a tip end connected to each of the air supply branch pipes 1
Three exhaust gas supply branch pipes 15B, 15 connected downstream from the damper 14 of 2B, 12C, 12D
C, 15D. As the combustion exhaust gas, treated combustion exhaust gas taken out from the rear of the rotary kiln may be used, or combustion exhaust gas discharged from another incinerator may be used.
The amount of combustion air and combustion exhaust gas supplied to the input hood 2 and both annular air supply chambers 8 and 9 is controlled depending on the internal temperature of the furnace wall 1 corresponding to each location. . That is, first, second, and third temperature detectors 17, 18, and 19 are arranged in the drying zone A, the pyrolysis/gasification zone B, the flaming combustion zone C, and the post-combustion zone D, and The opening degree of the dampers 14 and 16 of each branch pipe 12B and 15B connected to the charging hood 2 is determined by the signal from the temperature detector 17, and the opening degree of the damper 14 and 16 of each branch pipe 12B and 15B connected to the charging hood 2 is determined by the signal from the second temperature detector 18. Air supply chamber 8
Damper 1 of each branch pipe 12C, 15C connected to
Further, the opening degrees of the dampers 14 and 16 of the branch pipes 12D and 15D connected to the second annular air supply chamber 9 are adjusted by the signal from the third temperature detector 19. be done.

In the above configuration, from the input hopper 3 to the furnace wall 1
The waste introduced into the interior is first vaporized and dried in the drying zone A and the pyrolysis/gasification zone B, and the temperature is raised to the ignition temperature, and then flaming combustion is carried out in the flaming combustion zone C. After the fixed carbon content is burned in the combustion zone D, it is discharged from the discharge port 6 of the discharge hood 5 as incineration residue. By the way, primary air for combustion is supplied into the furnace wall 1 from the input hood 2, and secondary air for combustion is supplied into the furnace wall 1 from the first and second annular air supply chambers 8, 9. At this time, if the temperature of the flaming combustion zone C is high, the corresponding damper 16 is automatically controlled by the signal from the second temperature detector 18, and the combustion exhaust gas is transferred to the flaming combustion zone. C
Temperature control, that is, combustion control, can be easily achieved by supplying the fuel into the fuel tank. At the same time, the air dampers 14 are also adjusted to control the O ₂ concentration.

Of course, if the temperatures in the drying zone A, the pyrolysis/gasification zone B, and the combustion zone D are high, the temperature is controlled in the same manner as above based on the signals from the first and third temperature detectors 17 and 19. That is, combustion control is achieved. In this way, the temperature is controlled by supplying combustion exhaust gas to the middle part of the rotary kiln wall, that is, the flaming combustion zone, so compared to the conventional case where combustion air is supplied to control combustion. It is very easy to prevent the temperature rise in the flaming combustion zone, thereby reliably preventing damage to the furnace wall and the generation of NOx, and also easily achieving stable combustion. Further, since secondary air for combustion can be supplied to all combustion zones, complete combustion can be achieved in each zone even for waste whose properties change drastically.

Incidentally, in the above embodiment, a parallel flow type rotary kiln (suitable for waste with good ignitability and a large calorific value) in which combustion air is sent in the same direction as the waste was explained, but of course, the combustion air is sent in the same direction as the waste. It can also be applied to counter-current rotary kilns in which the air is sent in the opposite direction to the waste (suitable for waste with high moisture content and poor ignitability). In this case, as shown in FIG. 2, the auxiliary fuel injection nozzle 4 is provided in the exhaust hood 5, and the primary combustion air is supplied into the lower part of the exhaust hood 5.

Effects of the Invention As described above, according to the method of the present invention, the temperature is controlled by supplying the combustion exhaust gas to the intermediate part in the furnace wall of the rotary kiln, that is, the flaming combustion zone. Compared to the case where control is performed, the temperature rise in the flaming combustion zone can be extremely easily prevented, and therefore, damage to the furnace wall and generation of NOx can be reliably prevented, and stable combustion can be easily obtained. I can do it.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view of another embodiment. 1... Furnace wall, 8... First annular air supply chamber, 9...
...Second annular air supply chamber, 10...Flow rate adjustment valve, 1
1...Air intake pipe, 12...Air supply line, 1
3...Blower fan, 14...Damper, 15...
Exhaust gas supply line, 16... damper, 17...
First temperature detector, 18...Second temperature detector, 19
...Third temperature detector.

Claims (1)

[Claims] 1 It has a cylindrical furnace wall, and the waste is transferred from one of both open ends of this furnace wall to the other, and the waste transfer route includes a drying zone, a pyrolysis/gasification zone, a flaming combustion zone, and an oven. In a rotary kiln in which a combustion zone is formed, primary air for combustion is supplied from the open end of either one of the furnace walls, and
A combustion control method using combustion exhaust gas in a rotary kiln, characterized in that combustion exhaust gas is supplied from an intermediate part of the furnace wall, and the amount of the combustion exhaust gas supplied is controlled by the temperature inside the furnace wall.