JP2002156105A - External heat type kiln - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable improvement of processing capacity by effecting enhancement of heat transfer without increasing the size of the whole of an external heat type kiln. SOLUTION: An inner cylinder 3 having at one end in a longitudinal direction an inlet for waste 14 and at the other end an outlet and an outer cylinder 2 horizontally disposed in a state of being rotatively-drivable are concentrically contained such that a heating flow passage 7 is formed between the inner and the outer cylinders, and the waste 14 in the inner cylinder 3 is thermal decomposed and gasified by hot air 12. In a so formed external heat type kiln, a plurality of heat transfer tubes 19 formed in a plate-form manner such that gas passages 20 in a flat rectangular section are formed are mounted at given intervals in a peripheral direction on the inner peripheral surface of the inner cylinder 3. Each heat transfer pipe 19 is formed in a spiral state in a longitudinal direction. Hot air 12 is made to flow, also through the gas passage 20 of the heat transfer pipe 19 to effect enhancement of heat transfer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external heat type kiln for subjecting waste such as municipal waste to pyrolysis gasification.

[0002]

2. Description of the Related Art In recent years, waste materials are thermally decomposed by heating in a low oxygen atmosphere, and the generated pyrolysis gas and pyrolysis residues (carbon content and ash content) are burned at a high temperature in a combustion / melting furnace and discarded. A gasification and melting system has been developed in which the ash in the material is taken out as molten slag, and demonstration operation has been performed in some parts. In such a method, a rotary kiln is employed to thermally decompose the waste into gas, and the waste is indirectly heated and dried by heat from the outside so as to be thermally decomposed.

[0003] As shown in FIG. 3, an external heat type kiln used to pyrolyze waste gas into a pyrolysis gas is formed by connecting each end of a laterally placed outer cylinder 2 in the longitudinal direction. The fixedly arranged inlet tube 4 and outlet tube 5 are rotatably supported via a rotary joint 6, and the outer tube 2 is arranged to be inclined such that the outlet tube 5 side is lower than the inlet tube 4 side. The inner cylinder 3 is concentrically housed in the outer cylinder 2 so that a heating channel 7 is formed between the outer cylinder 2 and the inner cylinder 3 and the outer cylinder 2 and the inner cylinder 3 rotate integrally. The kiln body 1 has a double-cylinder structure, and both ends of the inner tube 3 serving as an inlet and an outlet are connected to a supply pipe 8 and a discharge pipe 9 having smaller diameters than the inner cylinder 3. As a configuration in which the supply pipe 8 and the discharge pipe 9 are connected to each other via the face plate 3a and the outlet pipe 5 and the outlet pipe 5 respectively, A state in which the hot air 12 as a heating gas introduced from the hot air supply port 10 of the mouth tube 5 is allowed to flow out of the hot air outlet 11 of the inlet tube 4 through the heating channel 7 and the kiln body 1 is rotated at a low speed. In the above, while the waste 14 charged in the charging hopper 13 is gradually supplied into the inner cylinder 3 through the supply pipe 8 of the inlet cylinder 4 by the screw feeder type duster 15, the waste 14 is supplied between the inner and outer cylinders of the kiln body 1. By flowing the hot air 12 from the outlet tube 5 side to the inlet tube 4 side in the formed heating channel 7, the waste 14 in the inner tube 3 is transferred to the high temperature heat transfer around the inner tube 3. The surface is heated, dried, pyrolyzed, and generated pyrolysis gas 14a
Is transferred to the separation chamber 16 through the discharge pipe 9 of the outlet tube 5 and then taken out from the upper part to be directly sent to the downstream combustion / melting furnace. The pyrolysis residue 14b containing metals is discharged from the discharge pipe 9. After being transferred to the separation chamber 16 through the interior 9, the metal is taken out from the lower portion, subjected to a metal separation step, and then sent to the combustion / melting furnace.

However, in the case of the above kiln, the inner cylinder 3
Since the heat transfer surface is the only external heat transfer method, the heat transfer area is small, and in order to increase the processing capacity, it is necessary to increase the diameter or length of the inner cylinder 3. However, there is a problem that the size becomes large.

Therefore, conventionally, as shown in FIG.
Inside the cylinder 17, a number of heat transfer tubes 18 are arranged in a circular shape in parallel and arranged in a straight line, so that hot air flows in each heat transfer tube 18 to increase the heat transfer area and increase the processing capacity. A scheme for increasing the level has been proposed.

[0006]

However, in the case of the system shown in FIG. 4, the waste is entangled with the heat transfer tubes 18 or the wastes pass through the gaps between the heat transfer tubes 18 and move into the cylinder 17. This causes a problem that stable operation cannot be performed.

In view of the above, the present invention provides an external heat type kiln that allows waste in an inner cylinder to contact a heat transfer surface for a long time and efficiently transports waste. It is intended to be able to operate.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an outer cylinder which is rotatably driven and placed horizontally, in which one end in the longitudinal direction has a waste inlet and the other end has an outlet. The cylinder is housed concentrically so that a heating channel is formed between the outer cylinder and the inner cylinder and the outer cylinder and the inner cylinder can be rotated integrally, and the waste supplied into the inner cylinder is removed. In an external heat type kiln which is heated by external heat by hot air flowing through the heating flow path to be pyrolyzed into gas, a flat rectangular cross-sectional shape is provided at a required circumferential position on an inner peripheral surface of the inner cylinder. A plurality of plate-shaped heat transfer tubes that form the gas passages are erected so as to protrude inward by a required amount, and are attached spirally over the entire length in the longitudinal direction. The configuration is such that hot air is circulated in the passage.

Since the heat transfer tube scoops up the waste with the rotation of the inner cylinder, the surface of the heat transfer tube and the inner surface of the inner cylinder serve as a heat transfer surface and can contact the waste. Is transported upwards, then dropped and scooped up again, so it is agitated and, at the same time, transported by the spiral action of the heat transfer tubes, thus increasing waste disposal capacity. Can be.

[0010] Further, by making the cross-sectional shape of each heat transfer tube into a U-shape or an arc shape, the amount of waste to be scooped can be further increased, and heat transfer can be promoted. it can.

Further, since each heat transfer tube is configured to be inclined forward in the rotation direction, it is possible to extend the time until the wastes scooped up by the heat transfer tube fall.
The time in contact with the heat transfer surface can be extended,
The heat transfer promoting effect can be further improved.

[0012]

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

FIGS. 1A and 1B show an embodiment of the present invention. In the configuration similar to that of the external heating type kiln shown in FIG. A plurality of plate-shaped heat transfer tubes 19 having flat rectangular cross-sectional gas passages 20 formed at the interval positions are required to have a required angle smaller than 90 degrees forward in the rotation direction (arrow X direction) of the kiln body 1. (In the present embodiment, inclined about 30 degrees with respect to the radial direction) and arranged in a spiral state over the entire length in the longitudinal direction so as to protrude inward in a fin-like shape by a required amount. While being fixed to the inner surface of the tube 3, both ends of each heat transfer tube 19 are opened outside the end face plate 3 a of the inner tube 3, so that the hot air 12 supplied from the hot air supply port 10 allows the inner and outer tubes 3, 2. Between the heating passage 7 and the gas passage 20 of each heat transfer tube 19. To. Other configurations are shown in FIG.
And the same parts are denoted by the same reference numerals.

While the kiln body 1 is rotated at a low speed, the waste 14 is supplied into the inner cylinder 3 through the supply pipe 8 by the duster 15 while the heating unit formed between the inner and outer cylinders 3 and 2 is heated. When the hot air 12 is caused to flow through the gas passage 20 of each heat transfer tube 19 attached to the flow path 7 and the inner tube 3, the waste 14 is passed through the inner tube 3 while being passed through the inner tube 3.
The mixture is agitated, stirred and transported downstream, and is heated and dried by the external heat received from the inner cylinder 3 and the external heat received from the heat transfer tube 19 to be pyrolyzed into gas.

More specifically, as the inner cylinder 3 rotates, the inner cylinder 3
The waste 14 located in the lower part of the inside is sequentially scooped up by each heat transfer tube 19, and at this time, the waste 14 is heated by being in contact with both the surface of the heat transfer tube 19 and the inner surface of the inner cylinder 3. Therefore, the heat transfer area is larger than in the case where only the inner surface of the inner cylinder 3 is in contact with the inner surface, and the heat transfer can be promoted.

The external heat type kiln of the present invention has an inner cylinder 3 having an inner diameter of 1500 mm, supply pipes 8 and discharge pipes 9 having an inner diameter of 700 mm, nine heat transfer tubes 19, and a cross section of heat transfer tube 19. Dimension is 75mm × 400mm, heat transfer area is 11.9m ²
The heat transfer area was compared with that of a conventional external heat type kiln having the same size and having only the outer peripheral surface of the inner cylinder 3 as shown in FIG. 2.52 times the heat transfer area was obtained. Similarly, the external heating type kiln of the present invention has an inner cylinder 3 having an inner diameter of 2800 mm, supply pipes 8 and discharge pipes 9 each having an inner diameter of 1450 mm, the number of heat transfer tubes 19 being eight, and a cross-sectional dimension of heat transfer tubes 19. Is 75mm ×
When the heat transfer area is 650 mm and the heat transfer area is 19.2 m ² / length 1 m, the heat transfer area is 2.18 times as large as the conventional product of the same size having only the outer peripheral surface of the inner cylinder 3 as the heat transfer surface. Obtained. Therefore, in the case of the externally heated kiln of the present invention, the inner cylinder 3
The heat transfer surface can be formed about twice or more as large as the heat transfer area only when the outer peripheral surface is used, and the heat transfer can be promoted.

Further, as described above, the waste 14 scooped up by the heat transfer tube 19 is transported upward and dropped by its own weight, but the heat transfer tube 19 is inclined forward in the rotation direction. Because of the overhang, the time required for the scooped waste 14 to fall can be lengthened, which is more advantageous in promoting heat transfer. Further, as described above, the waste 14 is repeatedly scooped up, carried upward, and then dropped, so that the waste 14 is subjected to a large stirring action. It will be gasified and the heat transfer tube 1
Since 9 is attached in a spiral shape in the longitudinal direction, the waste 14 is subjected to the transporting action simultaneously with the above-mentioned stirring action, and the size can be reduced with an increase in the processing capacity.

In the above, since the heat transfer tube 19 has a flat rectangular cross-sectional shape and the front and back surfaces are flat, the waste 14 is repeatedly taken up and dropped during the cycle. There is no entanglement or snagging, and stable operation can be performed.

Next, FIGS. 2A and 2B show other embodiments of the present invention. In the same configuration as that shown in FIGS. 1A and 1B, FIGS. (A) shows a case where the cross-sectional shape of the heat transfer tube 19 is bent in a U-shape so as to protrude backward in the rotation direction, and FIG. Each case is shown as being curved in an arc shape so as to protrude backward in the direction.

When the heat transfer tube 19 is shaped as shown in FIGS. 2A and 2B, it can receive and lift more waste when the inner cylinder 3 rotates, and can transfer heat for a longer time. Therefore, it is more advantageous in terms of enhancing heat transfer, and the waste can be heated more effectively.

[0021]

As described above, according to the external heat type kiln of the present invention, one end in the longitudinal direction is set to the waste inlet and the other end is set to the outside in the laterally rotatable outer cylinder. The cylinder is housed concentrically so that a heating channel is formed between the outer cylinder and the inner cylinder and the outer cylinder and the inner cylinder can be rotated integrally, and the waste supplied into the inner cylinder is removed. In an external heat type kiln which is heated by external heat by hot air flowing through the heating flow path to be pyrolyzed into gas, a flat rectangular cross-sectional shape is provided at a required circumferential position on an inner peripheral surface of the inner cylinder. A plurality of plate-shaped heat transfer tubes that form the gas passages are erected so as to protrude inward by a required amount, and are attached spirally over the entire length in the longitudinal direction. The structure is such that hot air is circulated in the passage. Waste heat can be scooped up by the heat transfer tube, and the waste scooped up by the heat transfer tube repeats a cycle of being carried upward, falling and scooping up again, and is affected by the spiral shape of the heat transfer tube , Waste can be conveyed at the same time as stirring, so that the processing capacity can be increased, the overall size can be reduced, and the heat transfer tube is flat,
When the above cycle is repeated, waste does not become entangled, stable operation can be performed, and the cross-sectional shape of each heat transfer tube is made into a U shape or an arc shape, and further, By adopting a configuration in which each heat transfer tube is inclined forward in the rotation direction, it is possible to lengthen the time required to scoop up more waste and drop the waste, which is further advantageous in promoting heat transfer. And other excellent effects.

[Brief description of the drawings]

FIG. 1 shows an embodiment of an externally heated kiln of the present invention, in which (a) is a schematic cross-sectional side view of the whole, and (b) is (a).
FIG. 3 is an enlarged view in the direction of arrows AA in FIG.

FIG. 2 shows another embodiment of the present invention.
(B) shows different cross-sectional shapes of the heat transfer tubes in FIG.
FIG. 4A is a view corresponding to an enlarged view taken in the direction of arrows AA in FIG.

FIG. 3 is a schematic sectional side view showing an example of a conventional external heat type kiln.

FIG. 4 is a schematic view showing another example of a conventional external heat type kiln.

[Explanation of symbols]

 2 outer cylinder 3 inner cylinder 7 heating channel 12 hot air 14 waste 19 heat transfer tube 20 gas passage

Claims (3)

[Claims] 1. An inner cylinder having one end in a longitudinal direction and an outlet at the other end concentrically housed in an outer cylinder which is rotatably driven and horizontally placed, and which is concentric with the outer cylinder and the inner cylinder. A heating flow path is formed between the outer cylinder and the inner cylinder so that the outer cylinder and the inner cylinder can be rotated integrally, and the waste supplied in the inner cylinder is heated by external heat by hot air flowing through the heating flow path to generate heat. In an external heat type kiln which is made to be decomposed and gasified, a plurality of plate-shaped heat transfer tubes formed with flat rectangular cross-sectional gas passages at required circumferential positions on the inner peripheral surface of the inner cylinder. Are arranged so as to protrude inward by a required amount and spirally attached to the entire length in the longitudinal direction, so that hot air flows through the heating passage and the gas passage of each heat transfer tube. And external heating kiln. 2. The external heat type kiln according to claim 1, wherein the cross-sectional shape of each heat transfer tube is formed in a U-shape or an arc shape. 3. The external heat type kiln according to claim 1, wherein each heat transfer tube is inclined forward in the rotation direction.