Rotary furnace and method for prolonging retention time of pyrolysis gas in rotary furnace

Abstract

The invention relates to the technical field of waste pyrolysis, in particular to a rotary furnace and a method for prolonging the retention time of pyrolysis gas in the rotary furnace. A pyrolysis gas leading-out mechanism (40) of the rotary furnace comprises a leading-out opening (41), a collecting pipe (42) and a driving mechanism (43) used for driving the collecting pipe (42) to rotate, and the outer surface of the collecting pipe (42) can scrape coking bodies on the inner wall of a rotary furnace body (10). One end of the collecting pipe (42) is provided with a gas collecting port (421), and the other end of the collecting pipe (42) is communicated with the leading-out port (41), so that pyrolysis gas in the rotary furnace body (10) needs to enter the collecting pipe (42) through the gas collecting port (421), and reaches the leading-out port (41) after patrolling along the collecting pipe (42). According to the rotary furnace, the staying time of pyrolysis gas can be prolonged, coking bodies on the inner wall of the rotary furnace body can be scraped, and the heat transfer performance of the rotary furnace body can be improved through the multiple collecting pipes.

Description

Technical Field

[0001] The present invention relates to the technical field of waste pyrolysis, and particularly relates to a rotary kiln and a method for prolonging the residence time of pyrolysis gas in the rotary kiln. Background Art

[0002] Waste pyrolysis is one of the important application directions of rotary kilns. The basic structure of a rotary kiln includes a continuously rotating rotary kiln body and fixed head covers and tail covers at both ends. The rotary kiln body is rotationally sealed with the head cover and the tail cover, and the generated pyrolysis gas is led out through the outlet at the tail cover. For the pyrolysis gas generated by heating the waste, the closer it is to the tail cover, the higher the temperature of the waste and the greater the amount of pyrolysis gas generated, but the shorter the residence time of the pyrolysis gas inside the rotary kiln body. The macromolecular non-condensable gas generated by the pyrolysis of the material often causes blockage of the subsequent pyrolysis gas pipeline.

[0003] Prolonging the residence time of pyrolysis gas in the rotary kiln body is beneficial to increasing the temperature of the pyrolysis gas and even causing preliminary cracking of the pyrolysis gas, thereby reducing the content of macromolecular components in the pyrolysis gas and reducing the probability of blocking the subsequent pipeline due to pyrolysis gas condensation. The applicant has proposed a pyrolysis furnace with adjustable heating mode, which is recorded in Chinese Patent Document CN113831922A. When using the direct thermal desorption mode, the heating jacket of the furnace body is used as a heat preservation and dust reduction space, and the pyrolysis gas is led out from the inside of the furnace body and travels along the heating jacket once. This method can reduce the probability of blockage of the subsequent pipeline.

[0004] Secondly, coking of pyrolysis materials on the inner wall of the rotary kiln is a recognized technical pain point of rotary kilns. The existing solutions mainly include the coating method and the scraping method. For example, a kiln tail anti-coking coating disclosed in Chinese Patent Document CN113321983A and a high-temperature resistant anti-coking coating disclosed in Chinese Patent Document CN115558416A. Although the coating can improve the high-temperature lubrication performance inside the furnace body and help reduce coking in the furnace, due to the different properties of the materials, the practical effects are unpredictable, and the scraping method is still used in practice. A plate-type scraper sludge thermal analysis anti-coking device disclosed in Chinese Patent Document CN 209522748U and a rotary kiln anti-coking device disclosed in Chinese Patent Document C219415776U both use scraping mechanisms to scrape the inside of the furnace body to separate the coking blocks from the inner wall of the furnace body.

[0005] Coking on the inner wall of the furnace body and blockage of the subsequent pipeline are two technical problems in different directions, and there is no technical solution in the prior art that simultaneously addresses the above two technical problems. Summary of the Invention

[0006] The first object of the present invention is to provide a rotary furnace, in order to reduce the probability of coking on the inner wall of the rotary furnace body and the probability of blockage of the pyrolysis gas generated in the subsequent pipeline.

[0007] To achieve the above object, the technical solution of the present invention is as follows: A rotary furnace, comprising A rotary furnace body, providing a pyrolysis site for materials, so that the organic matter in the materials is pyrolyzed to generate pyrolysis gas; A furnace head cover body, fixed to the feeding end of the rotary furnace body and providing support for the feeding mechanism; A furnace tail cover body, fixed to the discharging end of the rotary furnace body; A pyrolysis gas export mechanism, used to export the pyrolysis gas from the rotary furnace body, including an export port; The pyrolysis gas export mechanism further includes A collecting pipe, axially arranged along the inner wall of the rotary furnace body and located above the internal space of the rotary furnace body, so that when the rotary furnace body rotates relative to the collecting pipe, the outer surface of the collecting pipe can scrape the coking body on the inner wall of the rotary furnace body; one end of the collecting pipe has a gas collecting port, and the other end of the collecting pipe is communicated with the export port, so that the pyrolysis gas in the rotary furnace body needs to enter the collecting pipe through the gas collecting port and reach the export port after traveling along the collecting pipe; A driving mechanism, located outside the end of the rotary furnace body, for driving the collecting pipe to rotate self - sufficiently.

[0008] The inventive concept of this application lies in: using a structure to simultaneously solve or alleviate two different technical problems in the directions of coking on the inner wall of the rotary furnace and blockage of the subsequent pipeline.

[0009] In the prior art, the pyrolysis gas export port is located at the tail end of the rotary furnace body, resulting in an extremely short residence time of the pyrolysis gas generated at the tail end in the furnace body. After adopting the solution of this application, the generated pyrolysis gas needs to pass through the collecting pipe before reaching the export port, ensuring the residence time of the pyrolysis gas. The pyrolysis gas travels close to the inside of the furnace body, not only increasing the export temperature of the pyrolysis gas, but also some macromolecules in the pyrolysis gas may be preliminarily cracked in the collecting pipe, which is beneficial to reducing the probability of blockage of the subsequent pipeline.

[0010] In the prior art, the component for scraping the coking body on the inner wall of the rotary furnace body will inevitably produce a certain deformation, resulting in an increase in the gap between the component for scraping and the inner wall of the furnace body, affecting the removal effect of the coking body. The collecting pipe of this application is equipped with a driving mechanism, which can make the collecting pipe rotate self - sufficiently. The swinging during the self - rotation of the collecting pipe can make up for the above - mentioned defect, thereby ensuring the removal effect of the coking body.

[0011] As a preferred solution, the number of the collecting pipes is at least 3, and they are arranged in an arc shape in the internal space of the rotary furnace body. As the number of the collecting pipes increases, on the one hand, the pyrolysis gas generated can be timely exported from the rotary furnace body, and on the other hand, the number of times the collecting pipes scrape the inner wall of the rotary furnace body can be increased. Most importantly, it can cause a certain degree of blockage to the rising pyrolysis gas, reducing the chance of the pyrolysis gas contacting the inner wall of the rotary furnace body. Then, the coking body that would originally form on the inner wall of the rotary furnace body may instead coke on the surface of the collecting pipes, reducing the probability that the heat transfer effect of the rotary furnace body is affected and being conducive to ensuring the stability of the pyrolysis effect. When the collecting pipes rotate regularly, the coking body formed on the surface of the collecting pipes is removed due to the friction between the collecting pipes or the friction between the collecting pipes and the inner wall of the rotary furnace body.

[0012] As a further preferred solution, the spatial position of the collecting pipes does not exceed 1 / 2 of the internal space of the rotary furnace body. The pyrolysis material is in the space below 1 / 2 of the rotary furnace body, and the collecting pipes do not directly contact the pyrolysis material, so it is not easy for the material to block the gas collection ports of the collecting pipes.

[0013] As a preferred solution, the gas collection ports on the collecting pipes are arranged close to the furnace tail hood body to ensure that the pyrolysis gas has a longer traveling distance.

[0014] As a further preferred solution, a gas collection chamber is arranged outside the furnace head hood body. The gas collection chamber is only connected to the internal space of the rotary furnace body through the collecting pipes, so that the pyrolysis gas in the rotary furnace body needs to enter the gas collection chamber through the collecting pipes; the export is opened on the surface of the gas collection chamber.

[0015] As a further preferred solution, a rotary joint is arranged on the collecting pipe between the gas collection chamber and the furnace head hood body, and a cut-off valve and a purge gas inlet are arranged on the collecting pipe close to the gas collection chamber side. During maintenance, the cut-off valve is closed and purge gas is introduced to clean the inside of the collecting pipe.

[0016] As a preferred solution, the driving mechanism is a sprocket driving mechanism.

[0017] Another object of the present invention is to propose a method for prolonging the residence time of pyrolysis gas in the rotary furnace, in order to increase the temperature of the pyrolysis gas or cause preliminary cracking of the pyrolysis gas to reduce the proportion of macromolecular components in the pyrolysis gas, thereby reducing the probability of blockage in the subsequent pipeline, and at the same time, the coking body on the inner wall of the rotary furnace body can be timely removed. The specific method is as follows: At least one collecting pipe is arranged axially along the inner wall of the rotary furnace body in the inner space of the rotary furnace body, so that when the rotary furnace body rotates relative to the collecting pipe, the outer surface of the collecting pipe can scrape the coke body on the inner wall of the rotary furnace body; one end of the collecting pipe is provided with an air receiving port, and the other end of the collecting pipe is connected with the outlet of the pyrolysis gas outlet mechanism, so that the pyrolysis gas in the rotary furnace body needs to enter the collecting pipe through the air receiving port and reach the outlet after traveling along the collecting pipe; the collecting pipe can rotate under the action of the driving mechanism.

[0018] As a preferred solution, the driving mechanism has a chain, which is wound in an S shape between the collecting tubes, so that adjacent collecting tubes rotate in opposite directions when the driving mechanism is started. When the collecting tubes are arranged densely, the reverse rotation of adjacent collecting tubes is conducive to the removal of coke on the collecting tubes.

[0019] As a preferred solution, the driving mechanism is started periodically.

[0020] In summary, the present invention can prolong the residence time of the pyrolysis gas and scrape the coke bodies on the inner wall of the rotary furnace body due to the collecting tubes arranged along the inner wall of the rotary furnace body. The multiple collecting tubes can also protect the inner wall of the rotary furnace body, so that the coke bodies that would originally be formed on the inner wall of the rotary furnace body may be coked on the surface of the collecting tubes instead, thereby ensuring the heat transfer performance of the rotary furnace body. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a front view of the present invention; Figure 2 for Figure 1 A cross-sectional view of Figure 3 for Figure 1 Right view of; Figure 4 is an axonometric view of the present invention; Figure 5 for Figure 4 Enlarged view of middle part B; Figure 6 for Figure 5 Enlarged view of the middle C part; Figure 7 for Figure 4 The left side view of FIG. 1 shows a left side view of FIG. 1 , in which the gas collecting cavity is omitted; Figure 8 for Figure 1 Enlarged view of part A in the middle.

[0022] In the figure: 10, rotary furnace body; 20, furnace head cover; 21, feeding mechanism; 22, gas collecting chamber; 30, furnace tail cover; 40, pyrolysis gas outlet mechanism; 41, outlet; 42, collecting pipe; 421, gas receiving port; 422, rotary joint; 423, intercepting valve; 424, purge gas inlet; 43, driving mechanism; 431, chain. Embodiment Example

[0023] The rotary kiln in the prior art includes a rotary kiln body 10, a furnace head hood 20, a furnace tail hood 30 and a pyrolysis gas outlet mechanism 40. Among them, the rotary kiln body 10 is used to provide a place for pyrolysis of materials, so that the organic matter in the materials is pyrolyzed to generate pyrolysis gas. The furnace head hood 20 is fixed at the feeding end of the rotary kiln body 10 and provides support for the feeding mechanism 21 at the same time. The furnace tail hood 30 is fixed at the discharging end of the rotary kiln body 10, and a discharging mechanism is connected to the bottom of the furnace tail hood 30. The pyrolysis gas outlet mechanism 40 for discharging the pyrolysis gas from the rotary kiln body 10 only includes a discharge port 41, and the discharge port 41 is generally opened at the top of the furnace tail hood 30.

[0024] The rotary kiln described in this application mainly improves the pyrolysis gas outlet mechanism 40. The main body of the pyrolysis gas outlet mechanism 40 is a collecting pipe 42. As Figure 1 、 Figure 2 shown, the collecting pipe 42 is axially arranged along the inner wall of the rotary kiln body 10, and both ends of the collecting pipe 42 are movably connected to the furnace head hood 20 and the furnace tail hood 30 respectively, and are rotationally sealed with the furnace head hood 20 and the furnace tail hood 30.

[0025] The number of the collecting pipes 42 is at least 3, and they are arranged in an arc above the inner space of the rotary kiln body 10. Above the inner space means that the collecting pipe 42 is located above the materials in the rotary kiln body 10, and generally does not exceed 1 / 2 of the inner space of the rotary kiln body 10. As Figure 3 shown, in this embodiment, the number of the collecting pipes 42 is 11. Of course, the number of the collecting pipes 42 can also be only 1. Its disadvantages are as follows: all the pyrolysis gas can only be discharged from 1 collecting pipe 42, and the pyrolysis gas discharge efficiency will be reduced; secondly, a large-area shielding of the upper space inside the rotary kiln body 10 by the collecting pipe 42 cannot be formed, and the inner wall attachment coking body of the rotary kiln body 10 cannot be replaced.

[0026] When the rotary kiln body 10 rotates relative to the collecting pipe 42, the outer surface of the collecting pipe 42 can scrape the coking body on the inner wall of the rotary kiln body 10. There must be a certain gap between the outer surface of the collecting pipe 42 and the inner wall of the rotary kiln body 10, and the thickness of this gap is preferably 2-5 mm. Under normal circumstances, the small-scale crosstalk during the rotation of the rotary kiln body 10 can remove part of the coking body in the gap. In this application, the collecting pipe 42 is provided with a driving mechanism 43 for driving the collecting pipe 42 to rotate self, which is located outside the end of the rotary kiln body 10 and is a sprocket driving mechanism. When the driving mechanism 43 starts regularly at intervals, it can swing the collecting pipe 42, and can impact the thin-layer coking body between the outer surface of the collecting pipe 42 and the inner wall of the rotary kiln body 10 to a certain extent, which is beneficial to the removal of the coking body in the gap.

[0027] AsFigure 2 As shown, the collecting pipe 42 has a gas collecting port 421 at one end located in the furnace tail hood 30, and a gas collecting cavity 22 is arranged outside the furnace head hood 20. The gas collecting port 421 is a hole opened on the collecting pipe 42. The guiding outlet 41 is located on the surface of the gas collecting cavity 22, and the gas collecting cavity 22 is communicated with the internal space of the rotary furnace body 10 only through the collecting pipe 42. The pyrolysis gas in the rotary furnace body 10 can only enter the collecting pipe 42 from the gas collecting port 421, and after traveling along the collecting pipe 42, it reaches the guiding outlet 31 on the gas collecting cavity 22. As Figure 4 、 Figure 5 shown, the gas collecting cavity 22 is arranged in a C shape above the feeding mechanism 21, is hollow inside, and the gas outlet end of the collecting pipe 42 is located inside the gas collecting cavity 22.

[0028] As Figure 6 、 Figure 7 shown, the driving mechanism 43 has a chain 431, and the chain 431 is wound around the collecting pipes 42 in an S shape, so that the adjacent collecting pipes 42 rotate in opposite directions when the driving mechanism 43 is started.

[0029] As Figure 6 、 Figure 8 shown, a rotary joint 422 is provided on the collecting pipe 42 between the gas collecting cavity 22 and the furnace head hood 20. When the collecting pipe 42 rotates driven by the chain 431, the section of the collecting pipe 42 connected to the gas collecting cavity 22 does not rotate therewith. On this section of the collecting pipe 42, a cut-off valve 423 and a purging gas inlet 424 are also provided. During the regular maintenance of the rotary furnace, the inside of the collecting pipe 42 can be purged.

[0030] The rotary furnace described in this application is suitable for treating organic solid waste such as industrial waste salt and waste circuit boards.

[0031] The method for extending the residence time of pyrolysis gas in the rotary furnace corresponding to the rotary furnace described in this application is specifically as follows: at least 1 collecting pipe is axially arranged along the inner wall of the rotary furnace body in the internal space of the rotary furnace body, and the shortest distance between the outer surface of the collecting pipe and the inner wall of the rotary furnace body is not greater than 10 mm, preferably 2 - 5 mm, so that when the rotary furnace body rotates relative to the collecting pipe, the outer surface of the collecting pipe can scrape the coking body on the inner wall of the rotary furnace body; one end of the collecting pipe has a gas collecting port, and the other end of the collecting pipe is located in an independently arranged gas collecting cavity, so that the pyrolysis gas in the rotary furnace body needs to enter the collecting pipe through the gas collecting port and reach the guiding outlet on the gas collecting cavity after traveling along the collecting pipe; the collecting pipe can rotate self-driven under the action of a driving mechanism, and the driving mechanism can be started at regular intervals. Since the chain of the driving mechanism is wound around the collecting pipes in an S shape, the adjacent collecting pipes rotate in opposite directions when the driving mechanism is started.

Claims

1. Rotary kiln, comprising a rotary kiln body (10) that provides a pyrolysis site for materials, enabling the organic matter in the materials to pyrolyze to generate pyrolysis gas; a furnace head hood body (20) fixed to the feed end of the rotary kiln body (10) and providing support for the feeding mechanism (21); a furnace tail hood body (30) fixed to the discharge end of the rotary kiln body (10); a pyrolysis gas export mechanism (40) for exporting pyrolysis gas from the rotary kiln body (10), including an export port (41); It is characterized in that: The pyrolysis gas export mechanism (40) further includes a collection pipe (42) axially arranged along the inner wall of the rotary kiln body (10) and located above the internal space of the rotary kiln body (10), such that when the rotary kiln body (10) rotates relative to the collection pipe (42), the outer surface of the collection pipe (42) can scrape the coking body on the inner wall of the rotary kiln body (10); one end of the collection pipe (42) has a gas collection port (421), and the other end of the collection pipe (42) is communicated with the export port (41), such that the pyrolysis gas in the rotary kiln body (10) needs to enter the collection pipe (42) through the gas collection port (421) and reach the export port (41) after traveling along the collection pipe (42); a driving mechanism (43) located outside the end of the rotary kiln body (10) for driving the collection pipe (42) to rotate self - sufficiently.

2. The rotary kiln according to claim 1, characterized in that: the number of the collection pipes (42) is at least 3, and they are arranged in an arc in the internal space of the rotary kiln body (10).

3. The rotary kiln according to claim 2, characterized in that: the spatial position of the collection pipe (42) does not exceed 1 / 2 of the internal space of the rotary kiln body (10).

4. The rotary furnace according to claim 1, wherein: the gas collection port (421) on the collection pipe (42) is arranged close to the furnace tail hood body (30).

5. The rotary kiln according to claim 1 or 2, characterized in that: a gas collection chamber (22) is arranged outside the furnace head hood body (20), and the gas collection chamber (22) is communicated with the internal space of the rotary kiln body (10) only through the collection pipe (42), such that the pyrolysis gas in the rotary kiln body (10) needs to enter the gas collection chamber (22) through the collection pipe (42); the export port (41) is opened on the surface of the gas collection chamber (22).

6. The rotary kiln according to claim 5, characterized in that: a rotary joint (422) is arranged on the collection pipe (42) between the gas collection chamber (22) and the furnace head hood body (20), and a cut - off valve (423) and a purge gas inlet (424) are arranged on the collection pipe (42) on the side close to the gas collection chamber (22).

7. The rotary furnace according to claim 1, characterized in that: The driving mechanism (43) is a sprocket driving mechanism.

8. A method for extending the residence time of pyrolysis gas in a rotary kiln, characterized in that: at least 1 collection pipe is axially arranged along the inner wall of the rotary kiln body in the internal space of the rotary kiln body, such that when the rotary kiln body rotates relative to the collection pipe, the outer surface of the collection pipe can scrape the coking body on the inner wall of the rotary kiln body; one end of the collection pipe has a gas collection port, and the other end of the collection pipe is communicated with the export port of the pyrolysis gas export mechanism, such that the pyrolysis gas in the rotary kiln body needs to enter the collection pipe through the gas collection port and reach the export port after traveling along the collection pipe; the collection pipe can rotate self - sufficiently under the action of the driving mechanism.

9. The method for prolonging the residence time of pyrolysis gas in a rotary kiln according to claim 8, characterized in that: The driving mechanism has a chain, and the chain is wound in an S shape between the collection pipes, so that the adjacent collection pipes rotate in opposite directions when the driving mechanism is started.

10. The method for prolonging the residence time of pyrolysis gas in a rotary furnace according to claim 8, characterized in that: The driving mechanism is started regularly.

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