JP5492338B1 - Rotary kiln and its operating method - Google Patents

Abstract

Provided is a rotary kiln that realizes improvement in combustion efficiency, increase in the amount of processed material, reduction in processing time, compactness, and no need for fuel.
A rotary kiln (1) in which an internal space of a kiln main body (10) is composed of a front-stage area (10a) on the inlet side and a rear-stage area (10b) on the outlet side, is eccentric with respect to an axis (X) in the vicinity of the inlet. The air supply port 22a is disposed at a position and jets air in the circumferential direction, and the agitation unit is provided at each of a plurality of locations along the axis. A plurality of stirring blades of each stirring portion are distributed on the inner periphery of the kiln body and protrude from the inner surface. The rear region includes steps provided at a plurality of locations along the axis X, respectively. Each step is formed such that the inner diameter on the outlet side of the kiln body is smaller than the inner diameter on the inlet side.
[Selection] Figure 1

Description

  The present invention relates to a rotary kiln that efficiently performs incineration or melting and a method for operating the rotary kiln.

  A rotary kiln is a rotary cylindrical kiln used for incineration of waste and combustion or melting of various processed materials. Generally, it is installed with an inclination so that the outlet side is lowered. The processing object thrown in from the inlet burns or melts in the process of gradually moving to the outlet while rolling on the inner surface of the slowly rotating kiln. The rotary kiln can be heated to a high temperature of 1,000 ° C. or higher, but in order to achieve such a high temperature, it is usually necessary to burn fuel such as oil or gas in the kiln using a burner. .

  Various techniques are provided for improving the efficiency of combustion or melting of a rotary kiln. In patent document 1, the lifter which is a spiral protrusion is formed in the kiln inner surface so that stirring of an incinerator may be performed constantly in a rotary kiln. In Patent Document 2, a plurality of blades for stirring are spirally disposed on the inner surface of a rotary kiln that rotates in a horizontal state. In Patent Document 3, a retention promoting dam ring is formed in order to realize an appropriate residence time of the metal scrap in the kiln. In Patent Document 4, a lifter having an inclined surface is formed on the inner surface of the kiln in order to realize an appropriate residence time of the processed material in the kiln. In Patent Document 5, a step is formed by making the inner diameter of the combustion zone on the inlet side smaller than the inner diameter of the melting zone on the outlet side in order to prevent the melt in the melting zone from entering the combustion zone. In Patent Document 6, the inner diameter of the inlet is made larger than the inner diameter of the outlet in order to promote stirring and prevent adhesion of the melt. In patent documents 7 and 8, in order to improve combustion efficiency, combustion air is supplied in a kiln.

JP-A-8-233234 Japanese Patent Laid-Open No. 10-54523 JP 10-62070 A JP 2008-124203 A JP 2001-227723 A JP 2001-272173 A JP 2001-227720 A Japanese Patent No. 4524387

  As described above, a structure is proposed in which various blades and lifters are formed on the inner surface of the kiln main body in order to promote stirring of the processed material and ensure an appropriate residence time. However, there is a demand for the processed material to reach a sufficiently high temperature and burn in a shorter time than the current rotary kiln and to complete the melting in a shorter time.

  In addition, in the case of a treated product containing moisture, it is necessary to first dry after the rotary kiln is charged, so a drying zone is required in the internal space of the kiln body before the combustion zone. As a result, there is also a problem that the axial length of the kiln main body becomes long and must be enlarged.

  In addition, since the fuel supply is required in most applications of the rotary kiln, there is a problem that the cost is increased.

  In view of the above-described situation, the present invention provides a rotary kiln capable of increasing the processing amount of the processed material, shortening the processing time, downsizing the kiln body, and further reducing the fuel supply by improving the combustion efficiency as compared with the conventional one. It aims at providing the operation method.

  In order to solve the above problems, the present invention provides the following configurations. The numbers in parentheses are reference numerals in the drawings to be described later, and are attached for reference.

One aspect of the present invention has a cylindrical kiln body (10) that is driven to rotate about an axis (X) having a predetermined gradient with respect to the horizontal direction, and the kiln body (10) is fireproof inside. A rotary kiln (1) formed by a wall (12) and having an inner space composed of a front region (10a) on the inlet side and a rear region (10b) on the outlet side, and the front region (10a) has an inlet An air supply port (22a) that is arranged in the vicinity of an eccentric position with respect to the shaft (X) and jets air in the circumferential direction, and along the axis (X) on the outlet side from the air supply port (22a) And a plurality of stirring blades that are distributed on the inner periphery of the kiln main body (10) and project from the inner surface. 14a, 14b, 14c, 14d, 14e, 14f) and a plurality of locations along the axis (X) in the rear region (10b) A plurality of steps respectively (16a, 16b, 16c), and step (16a) positioned closest to the inlet side of the plurality of steps (16a, 16b, 16c), the boundary between the front region (10a) And the other step (16b, 16c) has an inner diameter on the outlet side of the kiln body (10). Is formed so as to be smaller than the inner diameter on the inlet side, the thickness of the fire wall (12) becomes thicker toward the outlet side .

  In the above aspect, in the front region (10a), an annular shape is formed from the inner surface along the inner periphery of the kiln body (10) closer to the inlet side than the plurality of stirring portions (14a, 14b, 14c, 14d, 14e, 14f). It is preferable to further include a short path prevention dam (13) projecting into the stub.

  In the above aspect, in the preceding stage region (10a), the gap between any two adjacent stirring portions (14c, 14d) among the plurality of stirring portions (14a, 14b, 14c, 14d, 14e, 14f) It is preferable to further include a rectifying dam (15) projecting annularly from the inner surface along the inner periphery of the kiln body (10).

Another aspect of the present invention is a method for operating a rotary kiln according to the above aspect, wherein the fuel is not used for combustion and melting of the processed material, and only the retained heat due to the self-combustion of the processed material is used. Is.

  In the aspect of the rotary kiln of the present invention, the spiral airflow is generated by injecting air in the circumferential direction from the air supply port arranged at a position eccentric to the shaft in the vicinity of the inlet of the upstream region of the kiln body. It is formed throughout the kiln body from the inlet to the outlet. By this spiral air flow, the stirring of the processed material is promoted and the contact between the processed material and air is improved, so that the combustion of the processed material can be promoted.

  Furthermore, by providing the agitation part composed of a plurality of agitation blades provided in the preceding region at a plurality of locations along the axis, agitation is promoted with the pulverization of the processed material, and the contact with air is further enhanced This also promotes the combustion of the workpiece.

  With the configuration of the preceding stage region, high-temperature combustion of 1000 ° C. or more is realized in the preceding stage region of the kiln body, and combustion or incineration of the processed material is almost completed in the preceding stage region. As a result, since it is not necessary to secure a drying zone for a processed product containing moisture as in the conventional case, the axial length of the kiln main body can be shortened and the size can be reduced.

  Furthermore, each of the plurality of steps provided in the rear stage region of the kiln main body serves as a dam that dams the processed material by forming the inner diameter on the outlet side to be smaller than the inner diameter on the inlet side. At the same time, the gradient of the refractory wall in the internal space is corrected so as to approach the horizontal direction. As a result, it is ensured that the residence time of the processed material in the rear region is extended and sufficiently melted. Further, the formation of the plurality of steps increases the thickness of the fireproof wall of the kiln main body in the rear region, thereby improving the heat insulation. As a result, the heat transfer surface temperature becomes high and the temperature for melting becomes higher, so that stable melting and melting in a shorter time are possible.

  Further, preferably, in the preceding region, a short path preventing dam that protrudes in an annular shape on the inlet side from the plurality of agitating units is provided, so that the processed material introduced from the inlet slips or rolls vigorously. , It is possible to prevent entry toward the exit side at once. Thereby, it can prevent that processed material reaches | attains a back | latter stage area | region or exit, without fully combusting, and can reduce the loss of processing amount.

  Further preferably, in the preceding region, a rectifying dam that protrudes in an annular shape between two adjacent stirring portions is provided, so that when the processing object is thrown in at an interval in time, It is possible to equalize the temporal variation of the amount of the processed material passing through the, and to ensure that a certain amount of the processed material continuously moves.

  Since the rotary kiln of the present invention is configured to increase the combustion efficiency and the melting efficiency as a whole, it can be performed using only the retained heat generated by the self-combustion without using the fuel in normal operation. This can be achieved by combining the processed products so that the amount of heat can maintain the melting temperature. Thereby, a combustion process and a melting process can be performed at low cost.

  The rotary kiln of the present invention is a rotary kiln having the same outer shape and the same volume of internal space, and at least about twice as much combustion melting per hour as compared with a rotary kiln that does not include at least an air supply port, a plurality of stirring units, and a plurality of steps. Processing capacity can be demonstrated.

  The air supply port, the plurality of agitating units and the plurality of steps, and the short path prevention dam and the rectifying dam, which are the components of the rotary kiln of the present invention, are added to the existing rotary kiln not equipped with these to realize the configuration of the present invention. Therefore, it can be implemented at low cost.

FIG. 1 is a schematic sectional view showing an example of the rotary kiln of the present invention. 2 is a cross-sectional view taken along the line AA in FIG. 3 is a cross-sectional view taken along the line BB in FIG. 4 is a cross-sectional view taken along the line CC in FIG. 5 is a cross-sectional view taken along the line DD in FIG.

  Embodiments of the present invention will be described below with reference to the drawings showing examples. The rotary kiln of the present invention described below is not limited to a specific purpose of use and processed material, and can be implemented as various rotary kilns. Therefore, the characteristic configuration of the present invention can be appropriately modified in material, number, dimensions, etc. according to the intended use of the rotary kiln to be applied and the necessity of the processed material.

  The treatment performed in the rotary kiln of the present invention may be only combustion (incineration), combustion (incineration) and melting, or only melting. As the processed material, a wide variety of substances such as organic substances, inorganic substances, plastics, metals, or mixtures thereof can be targeted. Below, the example of application to the rotary kiln which incinerates and melts a processed material is explained.

  FIG. 1 is a schematic sectional view showing an example of the rotary kiln of the present invention. 2 is a cross-sectional view taken along the line AA in FIG. 3 is a cross-sectional view taken along the line BB in FIG. 4 is a cross-sectional view taken along the line CC in FIG. 5 is a cross-sectional view taken along the line DD in FIG.

  Please refer to FIG. The rotary kiln 1 includes a kiln main body 10 and a charging unit 20. The kiln main body 10 is generally cylindrical and has one end as an inlet 18 and the other end as an outlet 19. The cylindrical axis X of the kiln body 10 is usually installed with a predetermined gradient θ with respect to the horizontal direction H so that the outlet 19 side is lower than the inlet 18 side. During operation of the rotary kiln 1, the kiln main body 10 is rotated around the axis X as indicated by the black arrow R.

  A charging unit 20 is installed in the front stage of the inlet 18. The input unit 20 includes an input shooter 21 into which a processed material is input. The input shooter 21 opens at the inlet 18 of the kiln body 10. Although not shown, a secondary combustion device, a molten slag recovery device, and the like are installed at the subsequent stage of the outlet 19 depending on the purpose of use.

  The kiln main body 10 includes an outer shell cylinder 11 made of a steel plate, and a fire wall 12 made of a refractory material such as a castable refractory fixed to the inside thereof. Between the inlet 18 and the outlet 19, there is a substantially cylindrical internal space surrounded by the inner surface of the fire wall 12. This internal space is functionally divided into a front region 10a on the inlet 18 side and a rear region 10b on the outlet 19 side. In this example, the front region 10a is a region for mainly burning the processed material, and the rear region 10b is a region for mainly melting the processed material.

  Please refer to FIG. 1 and FIG. In the vicinity of the inlet of the upstream region 10a, an air injection nozzle 22 that is attached to the input unit 20 and extends into the internal space is provided. The air injection nozzle 22 extends substantially parallel to the axis X at a position eccentric from the axis X, which is the rotation axis, and an air supply port 22a facing in the circumferential direction is opened on the side surface near the tip. At the time of operation, since air flows so as to stir the processed material in the circumferential direction from the air supply port 22a, a spiral air flow as indicated by a white arrow F is generated. This spiral air flow is preferably formed over the entire length from the inlet 18 to the outlet 19. The processed air and air are in good contact with each other by the spiral air flow, and combustion and melting are promoted.

  Please refer to FIG. 1 and FIG. In the front region 10a, a short path prevention dam 13 is provided on the outlet side of the air supply port 22a. The short path prevention dam 13 protrudes in an annular shape from the inner surface along the inner periphery of the fireproof wall 12 of the kiln body 10. The short path prevention dam 13 serves as a weir for preventing the processed material introduced from the inlet 18 from entering the outlet side at a stroke when it slides or rolls vigorously. Thereby, the suitable residence time of the processed material in the front | former area | region 10a is securable. The material of the short path prevention dam 13 may be the same as that of the fireproof wall 12, and the protrusion height is appropriately designed according to the processing object and the purpose of use.

  Please refer to FIG. 1 and FIG. In the upstream region 10 a, agitation portions are provided at a plurality of locations along the axis X on the exit side of the short path prevention dam 13. In the example shown in the figure, stirring portions 14a, 14b, 14c, 14d, 14e, and 14f are provided at six locations with predetermined intervals, respectively. Each stirring section is composed of a plurality of stirring blades. Referring to FIG. 4, for example, the fifth stirring unit 14e from the inlet side includes six stirring blades 14e1, 14e2, 14e3, 14e4, 14e5, and 14e6. These six stirring blades are distributed and arranged at equal angular intervals on the inner periphery of the fireproof wall 12 of the kiln body 10 and protrude from the inner surface of the fireproof wall 12. Each stirring blade has a flat plate shape, and planes on both sides thereof extend in the direction of the axis X with an appropriate length. When the kiln main body 10 is rotated, the processed material is sufficiently stirred by repeating scraping and dropping by the plane of each stirring blade. At the same time, the object to be treated and the air are in sufficient contact.

  In addition, in the example of illustration, although the stirring part is provided in six places, you may set the number suitably. Moreover, you may set suitably the axial direction space | interval with an adjacent stirring part. Furthermore, the number of stirring blades distributed on the circumference in one stirring unit is not limited to the six illustrated, and the number may be set as appropriate. Moreover, you may set suitably the angle space | interval (it is not restricted to an equal angle space | interval) with an adjacent stirring blade. Further, the number of the stirring blades may be different in the two different stirring sections, and the angular positions on the circumference of the stirring blades may be different in the two different stirring sections. For example, the adjacent stirring blades on the circumference may be staggered like a staggered arrangement. The material of the stirring blade may be a heat-resistant material such as a steel plate, for example, and the protrusion height is appropriately designed according to the processed material and the purpose of use.

  Furthermore, in the front | former area | region 10a, the rectification | damping dam 15 is provided in the area | region where several stirring parts 14a-14f exist. The rectifying dam 15 is provided between any two adjacent stirring portions of the plurality of stirring portions, in this case, between the stirring portions 14c and 14d. The rectifying dam 15 may be provided at a position other than this. The rectifying dam 15 protrudes in an annular shape from the inner surface of the refractory wall 12 along the inner periphery of the refractory wall 12 of the kiln body 10. The rectifying dam 15 equalizes the temporal variation of the amount of the processed material moving in the internal space when the processed material is input at intervals in time, and a certain amount of the processed material continuously moves. In addition, the residence time of the processed product is extended. The material of the protruding portion of the rectifying dam 15 may be the same as that of the fireproof wall 12, and the protruding height is appropriately designed according to the processing object and the purpose of use.

  Please refer to FIG. 1 and FIG. In the rear region 10b, step portions, that is, steps 16a, 16b, and 16c are provided at three locations along the axis X, respectively. Each step is formed such that the inner diameter on the outlet side of the kiln body 10 is smaller than the inner diameter on the inlet side. Each of the steps 16a, 16b, and 16c serves as a dam that dams the workpiece. Further, through these steps as a whole, the gradient of the inner surface of the refractory wall 12 in the rear region 10b is corrected so as to approach the horizontal direction H. As a result, it is ensured that the residence time of the processed material in the rear region 10b is extended and sufficiently melted.

  Furthermore, by forming a plurality of steps, the thickness of the fireproof wall 12 becomes thicker as it approaches the outlet side of the rear region 10b. As a result, the heat insulating property of the fire wall 12 is improved, the heat transfer surface temperature is increased, and the temperature for melting is further increased, so that stable melting is possible. In addition, melting in a shorter time is possible.

  Referring to FIG. 1 again, in the kiln body 10 of the rotary kiln 1 of the present invention, the size of the front region 10a can be defined as the axial length La from the inlet 18 to the most stirring portion 14f on the outlet side, and the rear region 10b. Can be defined as the axial length Lb from the most inlet side step 16a to the outlet 19. In the illustrated example, La is about 55% and Lb is about 42% with respect to the entire length of the kiln body. In this example, a region slightly larger than the front half of the entire length of the kiln main body 10 functions as a combustion region, and a region slightly smaller than the rear half of the total length functions as a melting region. In many conventional rotary kilns that perform combustion and melting, the combustion region and the melting region are not always clearly distinguished. However, the rotary kiln of the present invention can clearly distinguish between the combustion region and the melting region in terms of structure. It is easy to appropriately design the size of the combustion region and the melting region in accordance with the object and the purpose of use, thereby enabling an optimal design.

  When the rotary kiln of the present invention is operated, the processed material starts self-combustion by igniting the processed material with a burner or the like. Conventionally, it has been necessary to supply fuel during operation, but the rotary kiln of the present invention can be designed so as to reach a necessary combustion temperature or melting temperature only by self-combustion of the processed material. Specifically, the combination of the processed products is adjusted so that the heat quantity can maintain the melting temperature. Therefore, fuel supply is not required during normal operation.

  The rotary kiln of the present invention described above can be variously modified as long as the gist of the present invention is met. In addition, by modifying the existing rotary kiln that does not include all or some of the air supply port, short path prevention dam, stirring blade, rectifying dam and step components, It is also possible to construct the rotary kiln of the present invention.

<Comparison test>
Using the rotary kilns of the following Examples 1 to 3 and Comparative Example of the present invention, a comparative test was performed by incineration of waste.
(1) Example 1: Configuration of Rotary Kiln in FIG. 1 (2) Example 2: Configuration in which there is no step in the rear region in the configuration of the rotary kiln in FIG.
(3) Example 3: The structure of the rotary kiln of FIG. 1 is a structure in which the number of steps in the rear region and the number of stirring blades in the front region are each half.
(4) Comparative Example: A configuration that has the same outer shape and the same capacity as the rotary kilns of Examples 1 to 3 and does not include an air supply port, a short path prevention dam, a stirring blade, a rectifying dam, and a step.
<Test results>
(1) Example 1: It was possible to perform consistent and stable melting without using fuel during operation. The processing capacity was 120-140 tons / day.
(2) Example 2: No fuel was used during operation, but melting took more time than Example 1. The processing capacity was 100 to 120 tons / day.
(3) Example 3: During operation, a fuel burner was used to supply less than 5% of the total heat required for melting. The melting took more time than Example 2. The processing capacity was 90 to 110 tons / day.
(4) Comparative Example: A fuel burner was used to supply 10% or more of the total heat required for melting during operation. Melting took more time than any of Examples 1-3. The processing capacity was 70-80 ton / day.

  The processing capacity of the rotary kiln was 120 to 140 tons / day in Example 1, whereas it was 70 to 80 tons / day in Comparative Example. As a result, it has been proved that the rotary kiln of the present invention exhibits about twice the processing capacity as compared with the rotary kiln not equipped with the configuration of the present invention even though no fuel is used.

  In Example 1, the best result is obtained by the combined effect of the air supply port, the short path prevention dam, the stirring blade, the rectifying dam and the step in the configuration of FIG. The difference between the results of Example 1 and Example 2 is considered to be a difference in effect due to the presence or absence of a step in the subsequent region, and proves the effectiveness of the step in the subsequent region.

DESCRIPTION OF SYMBOLS 1 Rotary kiln 10 Kiln main body 10a Front stage area | region 10b Rear stage area | region 11 Outer shell cylindrical body 12 Fireproof wall 13 Short path prevention dam 14a, 14b, 14c, 14d, 14e, 14f Stirring part 15 Rectification dam 16a, 16b, 16c Step 18 Inlet 19 Outlet 20 Input section 21 Input chute 22 Air injection nozzle 22a Air supply port

Claims (4)

It has a cylindrical kiln body (10) that is driven to rotate about an axis (X) having a predetermined gradient with respect to the horizontal direction, and the kiln body (10) is formed with a refractory wall (12) on the inside. A rotary kiln (1) whose internal space is composed of a front stage area (10a) on the inlet side and a rear stage area (10b) on the outlet side,
In the preceding area (10a),
An air supply port (22a) that is disposed in a position eccentric to the axis (X) in the vicinity of the inlet and that injects air in the circumferential direction;
A plurality of stirring blades that are provided at a plurality of locations along the axis (X) on the outlet side of the air supply port (22a), and a plurality of stirring blades constituting each stirring portion are provided on the kiln main body (10). A plurality of stirring portions (14a, 14b, 14c, 14d, 14e, 14f) distributed on the inner periphery and projecting from the inner surface;
In the latter region (10b),
A plurality of steps (16a, 16b, 16c) respectively provided at a plurality of locations along the axis (X), and the step (16a) positioned closest to the entrance side among the plurality of steps (16a, 16b, 16c) , Located at the boundary with the preceding region (10a) and formed so that the inner diameter is smaller than the inner diameter of the preceding region (10a) at the boundary, each of the other steps (16b, 16c) The rotary kiln is characterized in that the fire wall (12) becomes thicker toward the outlet side because the inner diameter of the kiln main body is smaller than the inner diameter of the inlet side. In the front stage region (10a), a short projecting annularly from the inner surface along the inner periphery of the kiln body (10) closer to the inlet side than the plurality of stirring portions (14a, 14b, 14c, 14d, 14e, 14f) The rotary kiln according to claim 1, further comprising a pass prevention dam (13). In the front region (10a), the kiln body (10) is disposed between any two adjacent stirring portions (14c, 14d) of the plurality of stirring portions (14a, 14b, 14c, 14d, 14e, 14f). The rotary kiln according to claim 1 or 2, further comprising a rectifying dam (15) projecting in an annular shape from the inner surface along the inner circumference. The operation method of the rotary kiln according to any one of claims 1 to 3, wherein no fuel is used for combustion and melting of the processed material, and only the retained heat by the self-combustion of the processed material is used. How to operate the rotary kiln.

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