JP2002031483A - External heat type rotary kiln - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an external heat type rotary kiln/capable of drying and carbonizing or drying and baking or drying in a short time, based on a small fuel consumption by one unit, even for a material to be treated containing high water content. SOLUTION: The external heat type rotary kiln agitates and heats the material to be treated and thrown from one end 6a of a rotary cylinder 6 passing through a heating chamber 4, while transferring the material to another end 6b. In this kiln, a throwing side part of the material of the cylinder 6 is formed as a large diameter part 15, having a larger diameter than that of the another part, and a vent pipe 16 opened at both ends 16a with the changer 4 passing through the part 15 in the direction of the diameter is provided in the part 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an externally heated rotary kiln used for drying and carbonizing sewage sludge.

[0002]

2. Description of the Related Art Generally, sludge generated in a sewage treatment plant is:
After drying, it is further heated and carbonized, and the obtained carbide is used as a soil conditioner, a snow melting agent, and the like. As a treatment method for drying and carbonizing the sludge, a dewatered cake having a water content of about 80% was dried by hot air generated in a hot air generating furnace to a water content of about 40% in a drying furnace, and thus obtained. A post-drying charging method in which dry sludge is charged into an externally heated rotary kiln type carbonizing furnace and carbonized is widely used.

[0003] However, the above-mentioned processing method has a problem in that many devices such as a hot-air generating furnace, a drying furnace, and a carbonizing furnace are required, equipment costs are increased, and a large space is required for the processing facility.

[0004] Therefore, a direct charging system in which the drying step by the above-mentioned separate apparatus is omitted and a dewatered cake having a water content of about 80% is directly charged into a carbonization furnace to perform drying and carbonization has been attempted. Means that sludge with a high moisture content accumulates in a dense state near the input section in the rotary cylinder of the externally heated rotary kiln, so the heat transfer efficiency from the rotary cylinder is poor, and it takes a long time for drying, 1/3 compared to after-loading method
There is a problem that only a processing amount (per hour) can be obtained and the fuel cost of the burner for heating the rotary cylinder increases.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned conventional problems, and it is possible to use a single apparatus with a low fuel consumption even for a material to be treated having a high water content. It is an object of the present invention to provide an externally heated rotary kiln capable of performing drying and carbonization or drying and firing or drying in a short time.

[0006]

According to a first aspect of the present invention, there is provided an externally heated rotary kiln wherein an externally heated rotary kiln agitates and heats a material to be processed introduced from one end of a rotary cylinder passing through a heating chamber to the other end. In the rotary kiln, a portion of the rotary cylinder on the side of the material to be treated is a large diameter portion having a larger diameter than other portions.

According to the first aspect of the present invention, the material to be processed introduced from one end of the rotary cylinder is first transported along the inner wall surface of the large-diameter portion of the rotary cylinder while being transferred from the heating chamber to the rotary cylinder. Although heated by heat transfer through the cylinder wall, the large-diameter part has a larger diameter than the other parts, so the heat-transfer area for the material to be processed is large, compared to a straight cylindrical rotary cylinder without the large-diameter part. hand,
Due to the increase in the heat transfer area, a large amount of heat transfer to the workpiece in the workpiece input side portion of the rotary cylinder can be obtained.

According to a second aspect of the present invention, there is provided an externally heated rotary kiln which stirs and heats a material to be processed introduced from one end of a rotary cylinder passing through a heating chamber to the other end. A vent pipe is provided in a portion of the cylinder on the side where the material to be treated is introduced, the pipe being diametrically penetrated through the rotating cylinder and having both ends opened to the heating chamber.

According to the second aspect of the present invention, the ventilation pipe provided at the portion of the rotary cylinder on the side of the material to be treated is heated by the high-temperature atmosphere gas in the heating chamber flowing through the ventilation pipe. Since the outer peripheral surface of the trachea comes into contact with the material to be processed in the material input side portion, the amount of heat transfer to the material to be processed increases due to an increase in the heat transfer area by the ventilation tube, and the ventilation tube is rotated by the rotation of the rotary cylinder. Since the heat transfer is further promoted by agitating the material to be processed, a larger amount of heat transfer to the material to be processed in the material input side portion of the rotating cylinder can be obtained as compared with the case where there is no ventilation pipe.

According to a third aspect of the present invention, there is provided an externally heated rotary kiln which stirs and heats a material to be processed introduced from one end of a rotary cylinder passing through a heating chamber to the other end. The material input side portion of the tube is a large diameter portion having a larger diameter than other portions,
The large-diameter portion is provided with a ventilation pipe penetrating the large-diameter portion in the diameter direction and having both ends opened to the heating chamber.

According to the third aspect of the present invention, the formation of the large diameter portion and the provision of the ventilation pipe in the large diameter portion allow the transmission to the material to be processed as in the first and second aspects of the invention. Since the heat area is increased and the heat transfer is promoted by stirring the material to be processed by the ventilation pipe in the same manner as in the second aspect of the present invention, a large amount of the material to be processed in the material input side portion of the rotary cylinder is provided. The amount of heat transfer is obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to a first example shown in FIGS. 1 in the figure
In a carbonization furnace, which is an externally heated rotary kiln, sludge having a high water content is directly introduced, and drying and carbonization are performed in the same furnace. Reference numeral 2 denotes a furnace body made of a refractory material. A heating chamber 4 is formed above the hearth 3, and a secondary combustion chamber 5 is formed below the hearth 3.

Reference numeral 6 denotes a rotating cylinder made of metal, which extends through the heating chamber 4 in the longitudinal direction of the furnace body 2 and is disposed substantially horizontally with one end 6a slightly upward, and is fixed to a protruding portion outside the furnace. By rotating the rings 7, 7 by rollers supported by a stand (not shown), the rotary cylinder 6 is driven to rotate around the axis in one direction at a low speed. Reference numeral 8 denotes a chain sprocket for driving the rotation, which is fixed to the rotary cylinder 6.

Reference numeral 10 denotes a hopper arranged on one end 6a side of the rotary cylinder 6, for temporarily storing a sludge dewatered cake (sludge cake) W of sludge, which is an object to be processed. The screw conveyor 11 extends into the rotary cylinder 6 so that the charging port 11 a reaches near the end of the heating chamber 4. 12 is the other end 6b of the rotary cylinder 6.
Is a discharge pipe surrounding the other end 6b.

The rotary cylinder 6 has a stepped cylindrical shape in which a portion to be processed into which the material is introduced is a large-diameter portion 15 having a larger diameter than the other portions, and the large-diameter portion 15 is located in the vicinity of the input port 11a of the screw conveyor 11. Extends toward the center of the furnace body and has a length L
Depending on the moisture content of the dewatered cake W, the temperature of the heating chamber, etc., for example, 1/3 to 1/2 of the length of the heating chamber so that the drying of the dewatered cake W is performed during the transfer in the large diameter portion 15. Set to length.

16 is an appropriate number (4 in this example) in the large diameter portion 15.
The vent pipe provided in this manner penetrates the large-diameter portion 15 in the diameter direction, and is fixed to the large-diameter portion 15 by welding or the like so that both ends 16a, 16a open to the heating chamber 4. The two end portions 16a may be protruded outward from the outer peripheral surface of the large diameter portion 15, or one end thereof may be bent in the rotating cylinder rotating direction. Reference numeral 17 denotes a discharge pipe for blowing dry distillation gas generated in the rotary cylinder 6 into the heating chamber 4 and drying the gas in the heating chamber 4.

Reference numeral 21 denotes an auxiliary burner disposed on the hearth 3.
The fuel such as kerosene is burned to raise the temperature in the heating chamber 4. After the combustion heat of the carbonized gas generated from the dewatered cake due to the progress of drying and carbonization, the combustion of the auxiliary burner 21 is started. The amount is adjusted to the decreasing side. Reference numeral 22 denotes a secondary combustion burner for burning the unburned portion of the exhaust gas from the heating chamber 4, and reference numeral 23 denotes an exhaust port provided at an end of the secondary combustion chamber 5, which is connected to a chimney (not shown).

In order to carry out the drying and carbonizing treatment of sludge by the carbonizing furnace 1 having the above structure, the dewatered cake W having a water content of about 80% carried in from the sewage treatment facility is fed to the screw conveyor 1.
1 puts into the rotary cylinder 6 from one end 6a side. After the combustion of fuel by the auxiliary burner 21 in the heating chamber 4 and the generation of dry distillation gas in the rotation cylinder 6, the
The heated dewatered cake W is heated to a high temperature by the combustion of the dry distillation gas blown out of the rotary cylinder 6. Is heated by the heat transfer from

At this time, since the dewatered cake W has a high moisture content, the dewatered cake W is densely deposited almost completely in the large-diameter portion 15 near the inlet 11a. The heat transfer area for the layer is large, and the heat transfer amount is large (for example, when the large-diameter portion 15 having a diameter of 400 mm is provided with respect to the inner diameter of the rotary cylinder of 300 mm when the large-diameter portion is not provided), the heat transfer is about 1.3 times. Calories), and the dehydrated cake W
Drying is promoted.

A high-temperature atmosphere gas in the heating chamber 4 flows through the ventilation pipe 16 provided in the large-diameter portion 15 so that the ventilation pipe 16
Is heated to substantially the same high temperature as the large-diameter portion 15, so that heat transfer to the dewatered cake W filled in the large-diameter portion 15
6, the heat transfer area is increased by the outer peripheral area of the pipe wall of the ventilation pipe 16 (the ventilation pipe 16 is longer than in the case of the third example described later, so the heat transfer area is increased more than in the third example). The amount of heat transfer to the dewatered cake W is increased by that amount, and the dewatered cake W in the large-diameter portion 15 is stirred by the ventilation pipe 16 that rotates together with the rotary cylinder 6.
Further, heat transfer to the dewatered cake W is promoted.

The large diameter portion 1 is thus heated and stirred.
The sludge that has passed through 5 is dried, for example, with a water content of about 40%, is transferred into the small-diameter portion 18 following the large-diameter portion 15, and is further heated by the heat transfer from the cylindrical wall of the small-diameter portion 18. The carbonized sludge is carbonized and discharged from the coal discharge port 12 as carbonized sludge and collected by the discharge tube 13.

As described above, the large-diameter portion 1 of the rotary cylinder 6
5 and the provision of the ventilation pipe 16, a large heat transfer area for the dewatered cake W is obtained.
The heat transfer is promoted by the agitation action of the water, so that even for the dewatered cake W having a high water content, a large amount of heat is transferred at a portion where the material to be treated (the large-diameter portion 15) is supplied, and a short time is achieved with a small amount of fuel consumption. Drying proceeds, without the need for a drying furnace to dry the dewatered cake W to dry sludge as in the past,
The dehydration cake W having a high water content is directly charged, and the drying and carbonizing treatment can be efficiently performed.

Next, FIG. 3 shows a second embodiment of the present invention, which has the same configuration as that of the first embodiment except that the ventilation pipe 16 in FIG. 1 is removed. The parts are denoted by the same reference numerals and their detailed description is omitted.

In the carbonization furnace 31 of this example, the large-diameter portion 1
5, a large heat transfer area with respect to the dewatered cake W is obtained, and the processing material input side portion (the large-diameter portion 1) is formed in the same manner as in the first example except for the operation and effect due to the provision of the ventilation pipe 16.
In 5), the drying of the dewatered cake W proceeds in a short time under a small amount of fuel consumption due to a large heat transfer amount, and the dewatering cake W having a high water content can be directly introduced to efficiently perform the drying and carbonizing treatment. .

FIG. 4 shows a third embodiment of the present invention, in which the large diameter portion 15 shown in FIG.
Has the same configuration as that of the first example, except that it has a straight cylindrical shape having the same diameter as the small diameter portion 18.
The same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the carbonization furnace 32 of this embodiment, a ventilation pipe 16 whose both ends 16a are open to the heating chamber 4 is provided at the portion of the rotary cylinder 6 having the same diameter over the entire length on the side where the material to be treated is introduced. Due to the increase in the heat transfer area for the dewatered cake W by the trachea 16 and the stirring action on the dewatered cake W, a large portion is provided at the material input side portion, similarly to the first example, except for the operational effect of providing the large diameter portion 15. The drying of the dewatered cake W progresses in a short time with a small amount of fuel consumption due to the heat transfer amount, and the dewatering cake W having a high water content can be directly introduced to efficiently perform the drying and carbonizing treatment.

The present invention is not limited to the above examples. For example, the number and arrangement of the ventilation pipes 16 and the specific structure in the furnace body 2 may be other than those described above. May be used other than the auxiliary burner 21 as the heating means, or the discharge pipe 17 may be omitted.

In addition to the present invention, in addition to drying and carbonizing sewage sludge, drying and carbonizing various organic materials to be treated, such as wood chips, pulp sludge, marine waste, and the like, tile materials,
Drying and firing of various inorganic materials to be treated, such as mountain clay and silica clay,
The present invention can also be applied to an externally heated rotary kiln for drying various organic or inorganic materials to be treated.

[0029]

As described above, according to the first aspect of the present invention, since the processing material input side portion of the rotary cylinder has a large diameter portion, the processing material which is charged into the rotary cylinder and is in the drying step. The amount of heat transferred to the material increases, and drying and carbonization or drying can be performed in a short time with a small amount of fuel consumption by a single device without using a separate drying device, even for materials to be treated with a high moisture content. And baking or drying.

According to the second aspect of the present invention, a ventilation pipe is provided at the portion of the rotary cylinder on the side where the material to be treated is introduced, so that the ventilation pipe is diametrically penetrated through the rotary cylinder. As the amount of heat transfer to the material to be treated increases, the heat transfer is promoted by the stirring action on the material to be treated, and even for the material to be treated having a high moisture content, a single device can be used without using a separate drying device. Drying and carbonizing or drying and firing or drying can be performed in a short time with low fuel consumption.

According to the third aspect of the present invention, the large-diameter portion is provided at the portion of the rotary cylinder on which the material to be treated is supplied, and the ventilation pipe penetrating the large-diameter portion in the diameter direction is provided. The heat transfer to the material to be processed in the drying step, which is introduced into the rotating cylinder by the section and the ventilation pipe, is increased, and the heat transfer is promoted by the stirring action of the ventilation pipe to the material to be processed. For a material, drying and carbonizing or drying and firing or drying can be performed in a short time with a small amount of fuel consumption without using a separate drying device.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an externally heated rotary kiln showing a first example of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a longitudinal sectional view of an externally heated rotary kiln showing a second example of the embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of an externally heated rotary kiln showing a third embodiment of the present invention.

[Explanation of symbols]

1: Carbonization furnace (rotary kiln with external heating) 4: Heating chamber
Reference numeral 6: rotating cylinder, 6a: one end, 6b: other end, 11: screw conveyor, 11a: inlet, 15: large diameter part, 16
... vent pipe, 16a ... both ends, 31 ... carbonization furnace (externally heated rotary kiln), 32 ... carbonization furnace (externally heated rotary kiln).

Claims (3)

[Claims] 1. An externally heated rotary kiln that stirs and heats a material to be processed charged from one end of a rotary cylinder penetrating a heating chamber while transferring the material to the other end of the rotary cylinder. An externally heated rotary kiln characterized by having a large diameter portion having a larger diameter than other portions. 2. An externally heated rotary kiln which stirs and heats a material to be processed introduced from one end of a rotary cylinder penetrating through a heating chamber while transferring the material to the other end of the rotary cylinder. An externally heated rotary kiln, characterized in that a vent pipe penetrating the rotary cylinder in the diameter direction and having both ends opened to the heating chamber is provided. 3. An external heat type rotary kiln which stirs and heats a material to be processed charged from one end of a rotary cylinder penetrating through a heating chamber while transferring the material to the other end, wherein the material input side portion of the rotary cylinder is A large-diameter portion having a diameter larger than that of the other portion, and a ventilation pipe which penetrates the large-diameter portion in the diameter direction and has both ends opened to the heating chamber is provided in the large-diameter portion. Thermal rotary kiln.