JP4078701B2 - Rotary kiln - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an indirect heating type rotary kiln in which waste (for example, municipal waste) is pyrolyzed and gasified.
[0002]
[Prior art]
In recent years, as a next-generation waste treatment system, waste is heated and pyrolyzed in an inert atmosphere, and the generated pyrolysis gas and pyrolysis residue (carbon and ash) are reduced in the combustion / melting furnace. A gasification and melting method has been developed in which the amount of ash in the waste is combusted and the ash content in the garbage is taken out as molten slag, and some demonstration operations have been carried out. In such a system, a rotary kiln is employed in order to thermally decompose and gasify the waste, and the waste is indirectly heated and dried by heat from the outside to be thermally decomposed.
[0003]
The indirect heating type rotary kiln used for pyrolyzing waste gas is a double pipe that is disposed sideways so that it can be rotated and tilted about 3 degrees as shown in FIG. An inlet hopper 5 is provided at the inlet 2 at one end in the longitudinal direction of the outer cylinder 1 having a structure via a dust feeder 4, and the pyrolysis gas 6a and pyrolysis are provided at the outlet 3 at the other end in the longitudinal direction of the outer cylinder 1. In the state where the separation chamber 7 for separating the residue 6b is provided and the outer cylinder 1 is rotated at a low speed, the waste 6 thrown into the charging hopper 5 is gradually supplied into the outer cylinder 1 by the dust feeder 4. On the other hand, the heating gas 9 is circulated from the outlet 3 side toward the inlet 2 side in the heating flow path 8 formed in the double tube portion of the outer cylinder 1, thereby the waste 6 in the outer cylinder 1 is discharged. Pyrolysis gas 6a generated by heating and drying is removed from the upper part of the separation chamber 7. The pyrolysis residue 6b containing the metals is taken out from the lower part of the separation chamber 7 and sent to the combustion / melting process after the metal separation process. It is like that.
[0004]
Reference numeral 10 denotes a rotary joint, and 11 denotes a seal plate.
[0005]
However, in the case of the rotary kiln, since it is an indirect heating method and the heat transfer efficiency is poor, it is necessary to secure a sufficient contact area with the waste 6, and there is a problem that the outer cylinder 1 becomes long. Furthermore, since the outer cylinder 1 becomes long, a large installation area is required, and there is a problem that greatly affects land use.
[0006]
On the other hand, a multi-cylinder rotary kiln used for the treatment of dioxin-containing waste and the like is known as one that can increase the amount of treatment without making the outer cylinder 1 relatively long. That is, as schematically shown in FIG. 4, the multi-cylinder rotary kiln has a plurality of inner cylinders 13 housed and fixed in an outer cylinder 12 having a single-pipe structure that is horizontally disposed so as to be rotationally driven. A space formed between the cylinder 13 and the outer cylinder 12 is used as a heating flow path 8 so that heating gas is circulated.
[0007]
[Problems to be solved by the invention]
However, in the case of an indirect heating type multi-cylinder rotary kiln as shown in FIG. 4, the outer cylinder 12 has a large outer peripheral dimension, so that the amount of heat radiation is large, and the area of the heating channel 8 is inevitably determined. Because it is large, it is difficult to adjust the optimum flow rate according to the flow rate unless a structure such as a baffle is inserted, and the heating gas can be unevenly distributed and uneven in temperature, so that each inner cylinder 13 is heated evenly with the heating gas. There is also a problem that it is difficult.
[0008]
Therefore, the present invention enables the optimum flow rate to be adjusted according to the flow rate of the heating gas in the indirect heating multi-cylinder rotary kiln and allows the heating gas under the same condition to flow through each inner cylinder. In addition, it is intended to further reduce the heat radiation amount.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a plurality of double pipe structures composed of an inner pipe and an outer pipe in an outer cylinder that is disposed laterally so as to be rotationally driven with one end in the longitudinal direction as an inlet and the other end as an outlet. The inner cylinder of the book is stored and fixed, and the gap between the inner tube and the outer tube of the inner cylinder is used as a heating channel for circulating the heating gas, and the inner tube of each inner cylinder is discarded. So that the waste is thermally decomposed while being passed through the inner pipe of each inner cylinder , and further, the space between the outer cylinder and the inner cylinder It is set as the structure used as the heat insulation layer by enclosure.
[0010]
Since the inner pipe is composed of a gap between the outer pipes as a heating flow path, the optimum flow velocity can be adjusted according to the flow rate of the heating gas by adjusting the size of the outer pipe. The heating gas of the same condition can be made to flow through the cylinder, and the amount of heat radiation can be reduced because the inner and outer cylinders are provided as a heat insulating layer.
[0011]
Moreover, instead of making the space between the outer cylinder and the inner cylinder enclose air, the heat insulation is improved and the heat radiation amount is reduced by adopting a structure filled with a heat insulating material. Will be able to.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
1 (a) and 1 (b) show an embodiment of the present invention. An outer cylinder 12 having a single tube structure in which a refractory material 14 is lined with one end in the longitudinal direction as an inlet 2 and the other end as an outlet 3, The inner tube 13a and the outer tube 13b are arranged in a concentric manner inside the outer cylinder 12 with a required gap between them. A plurality of (three in the figure) inner cylinders 13 serving as heating passages 18 for the heating gas 9 are accommodated between the pipe 13a and the outer pipe 13b, and both ends in the longitudinal direction of the inner cylinder 13 are arranged as outer cylinders. 12 and the inner cylinders 13 are separated by a partition plate 15, and the inner pipes 13 a of the inner cylinders 13 are assembled at respective end positions to form collecting pipe parts 16, 17. , One collecting pipe portion 16 is located in the inlet 2 and the other collecting pipe portion 17 is located in the outlet 3, respectively. By allowing the heating gas 9 to flow in from the mouth 3 side, the heating flow path 18 between the inner tube 13a and the outer tube 13b of the inner cylinder 13 is regulated by the partition plate 15, and further flows. A heat insulation layer is formed by enclosing air in the space 19 formed between the inner surface of the outer cylinder 12 and the outer surface of the outer tube 13b of the inner cylinder 13 and between the inner cylinders 12.
[0014]
In FIG. 1, the same parts as those in FIG. 3 are denoted by the same reference numerals.
[0015]
As the outer cylinder 12 and the inner cylinder 13 are integrally rotated at a low speed, the waste 6 is supplied through the collecting pipe portion 16 of the inlet 2 by the dust feeder 4, and the inner pipe 13a and the outer cylinder 13 of each inner cylinder 13 are supplied. When the heating gas 9 is circulated through the heating flow path 18 formed between the pipes 13b, the waste 6 is heated and dried while being passed through the inner pipes 13a of the respective inner cylinders 13. The pyrolysis gas 6 a generated by pyrolysis is taken out from the upper part of the separation chamber 7 through the collecting pipe portion 17 of the outlet 3, while the pyrolysis residue 6 b is taken out from the lower part of the separation chamber 7.
[0016]
In the above, the heating gas 9 for indirectly heating the waste 6 is made to circulate through the heating flow path 18 formed between the inner tube 13a and the outer tube 13b constituting the inner cylinder 13. 4, the area outside the inner cylinder 13 is inevitably determined, and the flow rate can be easily adjusted in accordance with the flow rate as compared with the case where the area flows through the heating channel 8 having a large area. The heating gas 9 under the same conditions (temperature, flow rate, flow rate) can be flowed through the cylinder 13, and each inner cylinder 13 can be heated uniformly. In addition, since a heat insulating layer is formed by air sealing in the outer space 19 of the inner cylinder 13, the amount of heat released to the outside of the outer cylinder 12 can be reduced, and efficient operation can be performed. Can do.
[0017]
Next, FIG. 2 shows another embodiment of the present invention. In the same configuration as that shown in FIGS. 1 (A) and 1 (B), between the outer cylinder 12 and the inner cylinder 13 and the inner cylinder. Instead of enclosing air in the space 19 between the 13 members, the heat insulating material 20 is filled.
[0018]
If it shows as shown in FIG. 2, heat insulation can be improved further and the amount of heat dissipation to the exterior can be decreased more.
[0019]
In the above embodiment, the case where three inner cylinders 13 having a double-pipe structure are accommodated in the outer cylinder 12 is shown. Of course, various modifications can be made without departing from the scope of the present invention.
[0020]
【The invention's effect】
As described above, according to the rotary kiln of the present invention, the following excellent effects are exhibited.
(1) A plurality of inner cylinders having a double-pipe structure are housed and fixed in an outer cylinder arranged laterally so that it can be rotationally driven with one end in the longitudinal direction as the inlet and the other as the outlet. In addition, the gap between the inner tube and the outer tube of the inner cylinder is a heating flow path for circulating the heating gas, and the waste is allowed to pass through the inner tube of each inner cylinder, The waste is thermally decomposed while being passed through the inner pipe of each inner cylinder, and the space between the outer cylinder and the inner cylinder is configured as a heat insulating layer by air sealing. Therefore, the heating gas can flow through the gap between the outer tubes in the inner cylinder, so that the optimum flow rate can be adjusted according to the flow rate, and the heating gas of the same condition is set in each inner cylinder. Therefore, each inner cylinder can be heated evenly, and further, the inner and outer cylinders Since heat radiation to the outside can be suppressed by the heat insulating layer by air sealing in the interspace, the operating efficiency can be improved.
(2) Instead of allowing air to be enclosed in the space between the outer cylinder and the inner cylinder, the heat insulation effect can be further enhanced by adopting a configuration filled with a heat insulating material, so that the outside It is advantageous that the amount of heat released can be reduced.
[Brief description of the drawings]
1A and 1B show an embodiment of a rotary kiln of the present invention, where FIG. 1A is a schematic cut side view, and FIG. 1B is a view taken in the direction of arrows A-A in FIG.
FIG. 2 shows another embodiment of the present invention and is a cross-sectional view corresponding to FIG.
FIG. 3 is a schematic diagram showing an example of a rotary kiln.
FIG. 4 is a schematic longitudinal sectional view showing an example of a multi-cylinder rotary kiln.
[Explanation of symbols]
2 Inlet 3 Outlet 9 Heating gas 12 Outer cylinder 13 Inner cylinder 13a Inner pipe 13b Outer pipe 18 Heating flow path 19 Space 20 Thermal insulation

Claims (2)

A plurality of inner cylinders having a double-pipe structure are accommodated and fixed in an outer cylinder arranged laterally so as to be rotationally driven with one end in the longitudinal direction as an inlet and the other as an outlet, and The gap between the inner tube and the outer tube of the inner cylinder is used as a heating flow path for circulating a heating gas , and the waste is allowed to pass through the inner tube of each inner cylinder. Are thermally decomposed while being passed through the inner pipe of each inner cylinder , and further, the space between the outer cylinder and the inner cylinder is configured as a heat insulating layer by air sealing. A rotary kiln.   The rotary kiln according to claim 1, wherein a heat insulating material is filled in place of air in the space between the outer cylinder and the inner cylinder.

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