Steam circulation channel and large-scale sludge steam dryer

Abstract

The utility model discloses a steam circulation channel and large -scale sludge steam drying -machine relates to sludge drying equipment technical field, steam circulation channel includes first steam circulation mechanism, second steam circulation mechanism and drive first steam circulation mechanism and the rotation of second steam circulation mechanism cylinder, first steam circulation mechanism includes a plurality of air channel who sets up spirally along the outer wall of cylinder, second steam circulation mechanism, including the steam pipe of being located in the cylinder, and the space between a plurality of steam pipes constitutes the drying channel of to be dried material, and steam from the feed end of drying channel respectively flows into a plurality of steam pipes, and after gathering, flow into a plurality of air channel in the discharge end of drying channel, the outside wall of any steam pipe all is fixed with a plurality of anti -adhesion subassembly, and when the cylinder rotates, steam pipe and anti -adhesion subassembly drive to be dried material to move. Through the cooperation of first steam circulation mechanism and second steam circulation mechanism, solve the problem that the present drying -machine handles sludge steam utilization rate is low.

Description

Technical Field

[0001] This utility model relates to the technical field of sludge drying equipment, specifically a steam circulation channel and a large-scale sludge steam dryer. Background Technology

[0002] Sludge is a porous medium with a high water content, characterized by extremely high water content and large volume. Untreated sludge can contain over 95% water. The water in sludge is classified into free water, adsorbed water, and bound water. Free water, also known as unbound water, accounts for more than half of the total water content. It exists between sludge particles, does not bind to the sludge, and is easily separated, often removed by gravity concentration. Adsorbed water is formed by adsorption on the negatively charged surface of colloidal particles, creating a hydration film that allows water to be separated. Bound water is formed by capillary action between sludge particles and is removed by mechanical dewatering. Mechanical dewatering effectively removes surface water from sludge, but the water content of mechanically dewatered sludge is still insufficient for landfill disposal or energy recovery. Further heating and drying are necessary to remove capillary and adsorbed water from the sludge.

[0003] Common sludge heating and drying methods are divided into direct heating and drying and indirect heat conduction drying. Direct heating and drying usually involves direct contact between high-temperature gas and sludge. On the one hand, this produces a large amount of exhaust gas. On the other hand, the sludge surface will solidify rapidly, forming a wall-hanging phenomenon inside the heating equipment, resulting in insufficient drying and low heat utilization.

[0004] Indirect heat conduction drying equipment, such as disc dryers and paddle dryers, can avoid generating a large amount of exhaust gas, but their processing capacity is limited. Horizontal rotary steam dryers with large processing capacity are often used for drying small, loose materials. Their steam circulation channels are not suitable for highly viscous materials such as sludge. Therefore, there is an urgent need to design a steam circulation channel for a steam dryer suitable for large-scale sludge treatment. Utility Model Content

[0005] In view of this, the purpose of this application is to overcome the shortcomings of the prior art and to propose a steam circulation channel and a large sludge steam dryer.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0007] On one hand, a steam circulation channel includes a first steam circulation mechanism, a second steam circulation mechanism, and a cylinder that drives the first and second steam circulation mechanisms to rotate; the first steam circulation mechanism includes multiple air passages extending spirally along the outer wall of the cylinder; the second steam circulation mechanism includes multiple steam pipes located inside the cylinder, the multiple steam pipes being fixed to both ends of the cylinder in multiple annular shapes with equal radius differences relative to the radial direction of the cylinder along the axial direction of the cylinder, the space between the multiple steam pipes forming a drying channel for the material to be dried, steam flowing into the multiple steam pipes from the feed end of the drying channel and converging at the discharge end of the drying channel before flowing into the multiple air passages; wherein, the outer wall of any of the steam pipes is fixed with several anti-sticking components, and when the cylinder rotates, the steam pipes and anti-sticking components drive the material to be dried to move.

[0008] Preferably, each of the gas passages is provided with a plurality of first diversion plates, which divide each of the gas passages into a plurality of diversion chambers I. Each first diversion plate is provided with at least one first diversion hole and at least one first drain hole, and the diameter of the plurality of first diversion holes gradually increases along the steam flow direction.

[0009] Preferably, each of the steam pipes is provided with a plurality of second diversion plates, which divide the steam pipe into a plurality of diversion chambers II. Each second diversion plate is provided with at least one second diversion hole and at least one second drain hole, and the diameter of the plurality of second diversion holes gradually increases along the steam direction.

[0010] Preferably, a heating box is provided outside the cylinder, the air inlet of the heating box is connected to the outlet of each of the steam pipes, and the air outlet of the heating box is connected to each of the air passages.

[0011] Preferably, the anti-adhesion assembly includes a fixing sleeve, a metal chain, an arc-shaped tooth, and a support rod. The fixing sleeve is fixed to the outer circumferential surface of the steam pipe, the support rod is fixed between two fixing sleeves, the two ends of the metal chain are respectively hinged between two fixing sleeves, and the length of the metal chain is greater than the length of the support rod. The tail end of the arc-shaped tooth is fixed to the support rod, and the concave surface of the arc-shaped tooth is located on the side consistent with the rotation direction of the cylinder.

[0012] Preferably, the concave surface of the arc-shaped tooth is provided with a conical protrusion, which gradually narrows towards the end away from the support rod.

[0013] Preferably, when the metal chain is in a naturally drooping state, the distance from the lowest end of the metal chain to the steam pipe is less than the distance from the tail end of the arc-shaped tooth to the steam pipe.

[0014] Preferably, the cylinder is inclined, and the angle between the cylinder and the horizontal plane is 4°-7°, and the tail ends of the multiple steam pipes are all located at the lower end of the cylinder; the ratio of the length of any of the air passages to the length of the cylinder is 3:1-5:1.

[0015] Preferably, the distance from the center point of the first drain hole to the outer wall of the cylinder is less than its radius; the distance from the center point of the second drain hole to the inner wall of the steam pipe is less than its radius.

[0016] On the other hand, a large sludge steam dryer includes a steam circulation channel as described above, and also includes a rotatable shell and a cylinder that rotates synchronously with the shell. The first steam circulation mechanism and the second steam circulation mechanism are located on the inner and outer sides of the dryer cylinder, respectively. Each of the air passages is formed by two adjacent partitions dividing the space between the shell and the cylinder.

[0017] The beneficial effects achieved by this utility model due to the adoption of the above technical solution are as follows:

[0018] By coordinating the first and second steam circulation mechanisms, steam is recycled within the dryer, improving steam utilization and effectively preventing waste. In the first steam circulation mechanism, multiple spirally arranged air channels along the outer wall of the cylinder ensure even steam distribution, further enhancing heat transfer efficiency. Simultaneously, the design of the first diverter plate within the air channels, with its gradually enlarging first diverter holes, allows steam to gradually disperse during flow, preventing localized steam accumulation and improving heat uniformity.

[0019] In the second steam circulation mechanism, multiple steam pipes are fixed circumferentially along the cylinder axis, which not only ensures uniform drying of the sludge but also further improves the steam dispersion effect through the design of the second diversion plate inside the steam pipes. The design of the second diversion hole and the second drain hole on the second diversion plate allows the steam to fully contact the sludge inside the steam pipes while discharging excess liquid, ensuring both drying efficiency and quality.

[0020] Furthermore, the anti-adhesion component, through a combination of a fixing sleeve, metal chain, arc-shaped teeth, and support rod, not only prevents sludge from sticking to the steam pipe, but also further improves the sludge agitation through the concave surface and conical protrusion design of the arc-shaped teeth. This allows the sludge to have more thorough contact with the steam, thereby improving the uniformity and efficiency of drying. The inclined setting of the cylinder and the reasonable ratio of the air duct length to the cylinder length also allow the sludge to move more smoothly during the drying process, avoiding sludge accumulation and blockage.

[0021] In summary, the steam circulation channel of the large-scale sludge steam dryer of this utility model is reasonably designed and has a compact structure. It not only improves the utilization rate of steam and the drying efficiency, but also effectively avoids the problems of sludge adhesion and blockage, and has high practicality. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of a steam circulation channel according to the present invention;

[0023] Figure 2 This is a schematic diagram of the distribution structure of the steam pipes in one embodiment of a steam circulation channel according to the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of an anti-sticking component for a steam circulation channel according to the present invention;

[0025] Figure 4 This is a schematic diagram of the overall structure of a large-scale sludge steam dryer according to the present invention;

[0026] Figure 5 This is a schematic diagram of the rotor end of a large-scale sludge steam dryer according to the present invention.

[0027] Figure 6 This is a schematic diagram of the structure of the first distribution pipe of a large-scale sludge steam dryer according to the present invention;

[0028] Figure 7 This is a schematic diagram of the structure of the other end of the rotor of a large sludge steam dryer according to the present invention;

[0029] Figure 8 This is a schematic diagram of the structure of the second distribution pipe of a large-scale sludge steam dryer according to the present invention.

[0030] The attached diagram lists the components represented by each number as follows:

[0031] 1. First steam circulation mechanism; 11. Air passage; 12. Baffle plate; 13. First diverter plate; 130. First diverter hole; 131. First drain hole; 2. Second steam circulation mechanism; 21. Steam pipe; 22. Anti-adhesion component; 23. Second diverter plate; 230. Second diverter hole; 231. Second drain hole; 221. Metal chain; 222. Fixing sleeve; 223. Arc-shaped tooth; 224. Support rod; 225. Conical protrusion; 24. Fan-shaped fixing frame; 3. Cylinder; 4. Shell; 41. Idler roller; 42. Roller ring; 43. Drive gear; 44. 45. Driven gear; 46. Motor; 47. End cover; 48. Feed inlet; 49. First sealing cover; 40. Discharge outlet; 41. Second sealing cover; 42. Exhaust outlet; 53. Rotor; 54. First air inlet chamber; 55. Second air inlet chamber; 66. First rotary joint; 77. First air inlet pipe; 88. Second air inlet pipe; 99. Second air outlet pipe. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0033] The core of this invention is to provide a steam circulation channel and a large-scale sludge steam dryer to improve the working efficiency of processing large amounts of sludge using a horizontal rotary drum steam dryer.

[0034] The present invention will be described in detail with the following embodiments:

[0035] Example

[0036] refer to Figure 1-7 ,like Figure 1 and 4 As shown, a large sludge steam dryer has a rotatable shell 4 and a cylinder 3 that rotates synchronously with the shell 4. The cylinder 3 is placed inside the shell 4. Outside the shell 4, there are rollers 41, a rolling ring 42 fixed to the outside of the shell 4, a drive gear 43, a driven gear 44 fixed to the outside of the shell 4, and a motor 45. The motor 45 drives the drive gear 43 to rotate, thereby rotating the shell 4. The rollers 41 and the rolling ring 42 cooperate to ensure that the shell 4 rotates smoothly.

[0037] like Figure 4As shown, a rotor 5 is installed inside the cylinder 3. The rotor 5 passes through the cylinder 3, and both ends of the rotor 5 are fixed to the end caps 46 at both ends of the shell 4. Both ends of the rotor 5 are fixed to the rotors of the first rotary joint 6 and the second rotary joint 7. When the cylinder 3 rotates synchronously with the shell 4, the rotor 5 rotates synchronously.

[0038] like Figure 1 As shown, the steam circulation channel includes a first steam circulation mechanism 1 and a second steam circulation mechanism 2, wherein:

[0039] The first steam circulation mechanism 1 includes multiple air passages 11 that extend spirally along the outer wall of the cylinder 3. Each of the air passages 11 is formed by two adjacent partitions 12 that divide the space between the shell 4 and the cylinder 3. This jacket structure reduces heat loss and improves steam utilization.

[0040] The second steam circulation mechanism 2 includes multiple steam pipes 21 located inside the cylinder 3. The multiple steam pipes 21 are fixed to both ends of the cylinder 3 in a ring shape with equal radius difference along the axial direction of the cylinder 3 and relative to the radial direction of the cylinder 3. The space between the multiple steam pipes 21 forms a drying channel for the material to be dried (such as sludge, coal slime, etc.). Steam flows into the multiple steam pipes 21 from the feed end of the dryer and gathers at the discharge end of the dryer before flowing into multiple air passages 11.

[0041] like Figure 4 As shown, the material to be dried enters from the feed port 47 at the right end of the shell 4, and the dried material is discharged from the discharge port 48 at the left end of the shell 4. The water vapor in the material is discharged from the exhaust port 49 at the upper left end of the shell 4. The feed port 47 is installed on the first sealing cover 471, and the first sealing cover 471 and the shell 4 adopt a labyrinth seal structure. The discharge port 48 and the exhaust port 49 are installed on the second sealing cover 481, and the second sealing cover 481 and the shell 4 also adopt a labyrinth seal structure.

[0042] like Figure 4 , 5 As shown in Figure 6, the first rotary joint 6 includes a first air inlet pipe 61 and a second air inlet pipe 62. The rotor 5 has a double-layer hollow structure near the first rotary joint 6, including a first air inlet chamber 51 and a second air inlet chamber 52. The first air inlet chamber 51 is located inside the second air inlet chamber 52. High-temperature steam enters from the first air inlet pipe 61 and enters the first air inlet chamber 51 through a through hole communicating with the first air inlet chamber 51. It is also connected to the steam pipe 21 one-to-one through a plurality of first distribution pipes 53. The plurality of first distribution pipes 53 are fixed on the rotor 5 in a ring shape and are connected to the first air inlet chamber 51. The structure of the plurality of first distribution pipes 53 is as follows: Figure 7 As shown in the figure, the first distribution pipe 53, which is connected to the outer steam pipe 21, is not shown.

[0043] like Figure 4 , 7 As shown, the second rotary joint 7 includes a first air outlet pipe 71 and a second air outlet pipe 72. The rotor 5 has a double-layer hollow structure near the second rotary joint 7, including a first air outlet chamber 54 and a second air outlet chamber 55. The first air outlet chamber 54 is located inside the second air outlet chamber 55. The steam after heat exchange with the material to be dried passes through a plurality of first air collecting pipes 56 at the tail end of each steam pipe 21 and enters the first air outlet chamber 54 through a through hole connected to the first air outlet chamber 54, and is discharged from the first air outlet pipe 71. The plurality of first air collecting pipes 56 are connected to the steam pipes 21 one by one, and the plurality of first air collecting pipes 56 are fixed on the rotor 5 in a ring shape.

[0044] like Figure 4 , 5 As shown, the steam discharged from the first exhaust pipe 71 is transported to the second intake pipe 62, and enters the second intake chamber 52 through a through hole connected to the second intake chamber 52. It is then distributed to each air passage 11 by the second distribution pipe 57 at the left end of the second intake chamber 52. Figure 8 As shown, multiple second distribution tubes 57 correspond one-to-one with multiple airways 11.

[0045] like Figure 4 , 7 As shown, a plurality of second gas collecting pipes 58 are provided at one end of the rotor 5 near the second gas outlet pipe 72. The plurality of second gas collecting pipes 58 are fixed in a ring shape on the outside of the rotor 5. The steam in each gas passage 11 near the end of the second gas outlet pipe 72 flows into the second gas outlet chamber 55 through the plurality of second gas collecting pipes 58 and is discharged from the second gas outlet pipe 72 through the through hole communicating with the second gas outlet chamber 55.

[0046] It should be noted that, except for the two ends, the middle part of the rotor 5 is a solid structure. The first air inlet chamber 51 and the second air inlet chamber 52 are not connected to each other, and the first air outlet chamber 54 and the second air outlet chamber 55 are not connected to each other.

[0047] In actual use, the shell 4 and the cylinder 3 are set at an angle, and the angle between the cylinder 3 and the horizontal plane is 4°-7°. The tail ends of the multiple steam pipes 21 are all located at the lower end of the cylinder 3. This inclined setting is conducive to the discharge of dried sludge particles and the discharge of condensate generated in the steam pipes 21. It should be noted that in actual use, a drain valve is installed at the tail end of each steam pipe 21 to discharge condensate.

[0048] In the first steam circulation mechanism 1, the ratio of the length of any of the air passages 11 to the length of the cylinder 3 is 3:1-5:1. This spiral structure increases the steam travel distance, allowing the steam to be evenly distributed on the outer wall of the cylinder 3, further improving the heat transfer efficiency.

[0049] Preferably, the ratio of the length of the air passage 11 to the length of the cylinder 3 is 4:1.

[0050] In actual use, due to the long cylinder of the large steam dryer, the steam temperature difference between the front, middle and rear sections of the cylinder is large. In order to reduce the temperature difference and balance the steam flow distribution, multiple first diversion plates 13 are further provided in each of the multiple air passages 11. The multiple first diversion plates 13 divide any one of the air passages 11 into multiple diversion chambers I. The first diversion plate 13 is provided with at least one first diversion hole 130 and at least one first drain hole 131. The diameter of the multiple first diversion holes 130 gradually increases along the steam flow direction.

[0051] Correspondingly, in order to reduce the temperature difference, multiple second diversion plates 23 are provided in each of the multiple steam pipes 21. The multiple second diversion plates 23 divide any one of the steam pipes 21 into multiple diversion chambers II. The second diversion plate 23 is provided with at least one second diversion hole 230 and at least one second drain hole 231. The diameter of the multiple second diversion holes 230 gradually increases along the steam direction.

[0052] Preferably, to avoid condensate retention, a first drain hole 131 and a second drain hole 231 are provided. The distance from the center point of the first drain hole 131 to the inner wall of the shell 4 is less than its radius; the distance from the center point of the second drain hole 231 to the inner wall of the steam pipe 21 is less than its radius. Combined with the inclined structure of the cylinder 3, this ensures that the condensate is discharged smoothly.

[0053] In actual use, due to the long cylinder of the large steam dryer, the temperature of the steam discharged through the tail end of the steam pipe 21 is reduced. However, the temperature of this part of the steam is higher than the temperature of the outdoor air. It is directly discharged into the air, resulting in heat waste. In order to improve the utilization rate of this part of the steam, a heating box is installed outside the dryer shell. The air inlet of the heating box is connected to the outlet of each steam pipe 21, and the air outlet of the heating box is connected to each of the air passages 11.

[0054] Specifically, such as Figure 4 As shown, the air inlet of the heating box is connected to the first air outlet pipe 71, and the air outlet of the heating box is connected to the second air inlet pipe 62.

[0055] Based on the above structure, considering the characteristic of sludge being prone to sticking, several anti-sticking components 22 are fixed on the outer wall of the steam pipe 21. When the cylinder rotates, the steam pipe 21 and the anti-sticking components 22 drive the sludge to move.

[0056] like Figure 2As shown, specifically, the anti-adhesion component 22 includes a fixing sleeve 222, a metal chain 221, an arc-shaped tooth 223, and a support rod 224. The fixing sleeve 222 is fixed on the outer circumferential surface of the steam pipe 21, the support rod 224 is fixed between the two fixing sleeves 222, the two ends of the metal chain 221 are respectively hinged between the two fixing sleeves 222, and the length of the metal chain 221 is greater than the length of the support rod 224. The tail end of the arc-shaped tooth 223 is fixed on the support rod 224, and the concave surface of the arc-shaped tooth 223 is located on the side consistent with the rotation direction of the cylinder.

[0057] Preferably, the fixing sleeve 222, metal chain 221, arc-shaped tooth 223 and support rod 224 are all made of corrosion-resistant high-strength steel, which not only improves the service life of the equipment, but also provides good heat conduction.

[0058] In this structure, when the cylinder 3 rotates, the arc-shaped teeth 223 carry the sludge counterclockwise, exerting a squeezing effect on the sludge. Since the metal chain 221 is a flexible structure, after the sludge is squeezed, the metal chain 221 deforms, and the sludge adheres to the net-like structure formed by the metal chain 221 and the arc-shaped teeth 223. With the conduction of steam heat, the sludge gradually dries, and the dried sludge is discharged from the discharge port 48. The water vapor evaporated from the sludge is discharged from the exhaust port 49. The exhaust port 49 can be connected to a dust collector and a condensate collection device to collect dust and condensate generated during material drying. When the sludge in the net-like structure rotates to a certain height, it flips over. Under the action of gravity, the sludge chunks fall off and collide with the arc-shaped teeth 223, becoming smaller fragments. As the cylinder continues to rotate, the required sludge particles are finally formed, completing the drying of the sludge.

[0059] In the above structure, to ensure the realization of the function of the net-like structure, in actual setting, when the metal chain 221 is in a natural hanging state, the distance from the bottom end of the metal chain 221 to the steam pipe 21 is less than the distance from the tail end of the arc-shaped tooth 223 to the steam pipe 21.

[0060] Preferred, such as Figure 3 As shown, in order to improve the strength of the arc-shaped teeth 223 and facilitate better separation of sludge from the arc-shaped teeth 223, a conical protrusion 225 is provided on the concave surface of the arc-shaped teeth 223. The conical protrusion 225 gradually narrows towards the end away from the support rod 224, so that the sludge can fall off faster when it is at the critical point of falling off.

[0061] Preferably, to prevent the steam pipes 21 from deforming during long-term use, causing malfunctions and affecting the drying effect, fan-shaped fixing brackets 24 are also provided on the outside of the multiple steam pipes 21, such as... Figure 1 and 3 As shown.

[0062] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0063] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A vapor circulation channel, characterized by, It includes a first steam circulation mechanism (1), a second steam circulation mechanism (2), and a cylinder (3) that drives the first steam circulation mechanism (1) and the second steam circulation mechanism (2) to rotate; The first steam circulation mechanism (1) includes multiple air passages (11) spirally extending along the outer wall of the cylinder (3); the second steam circulation mechanism (2) includes multiple steam pipes (21) located inside the cylinder (3). The multiple steam pipes (21) are fixed to both ends of the cylinder (3) in multiple rings with equal radius differences along the axial direction of the cylinder (3) and relative to the radial direction of the cylinder (3). The space between the multiple steam pipes (21) forms a drying channel for the material to be dried. Steam flows into the multiple steam pipes (21) from the feed end of the drying channel and gathers at the discharge end of the drying channel before flowing into the multiple air passages (11). Among them, the outer wall of any of the steam pipes (21) is fixed with several anti-sticking components (22). When the cylinder (3) rotates, the steam pipe (21) and the anti-sticking components (22) drive the material to be dried to move.

2. The steam circulation channel according to claim 1, characterized in that, Each of the gas passages (11) is provided with a plurality of first diversion plates (13), which divide each of the gas passages (11) into a plurality of diversion chambers I. Each first diversion plate (13) is provided with at least one first diversion hole (130) and at least one first drain hole (131). The aperture of the plurality of first diversion holes (130) gradually increases along the steam flow direction.

3. The vapor cycle channel of claim 1 or 2, wherein, Each of the steam pipes (21) is provided with a plurality of second diversion plates (23), which divide each of the steam pipes (21) into a plurality of diversion chambers II. The second diversion plate (23) is provided with at least one second diversion hole (230) and at least one second drain hole (231), and the diameter of the plurality of second diversion holes (230) gradually increases along the steam direction.

4. The vapor cycle channel of claim 1 wherein, A heating box is provided outside the cylinder (3). The air inlet of the heating box is connected to the outlet of each of the steam pipes (21), and the air outlet of the heating box is connected to each of the air passages (11).

5. The vapor cycle channel of claim 1 wherein, The anti-adhesion assembly (22) includes a fixing sleeve (222), a metal chain (221), an arc-shaped tooth (223), and a support rod (224). The fixing sleeve (222) is fixed on the outer circumferential surface of the steam pipe (21). The support rod (224) is fixed between the two fixing sleeves (222). The two ends of the metal chain (221) are respectively hinged between the two fixing sleeves (222), and the length of the metal chain (221) is greater than the length of the support rod (224). The tail end of the arc-shaped tooth (223) is fixed on the support rod (224), and the concave surface of the arc-shaped tooth (223) is located on the side consistent with the rotation direction of the cylinder.

6. The vapor cycle channel of claim 5 wherein, The concave surface of the arc-shaped tooth (223) is provided with a conical protrusion (225), which gradually narrows towards the end away from the support rod (224).

7. The vapor cycle channel of claim 5 wherein, When the metal chain (221) is in a naturally drooping state, the distance from the bottom of the metal chain (221) to the steam pipe (21) is less than the distance from the tail end of the arc-shaped tooth (223) to the steam pipe (21).

8. The vapor cycle channel of claim 1 wherein, The cylinder is inclined and the angle between the cylinder and the horizontal plane is 4°-7°. The tail ends of the multiple steam pipes (21) are all located at the lower end of the cylinder. The ratio of the length of any of the air passages (11) to the length of the cylinder is 3:1-5:

1.

9. The vapor cycle channel of claim 3 wherein, The distance from the center point of the first drain hole (131) to the outer wall of the cylinder (3) is less than its radius; the distance from the center point of the second drain hole (231) to the inner wall of the steam pipe (21) is less than its radius.

10. A large-scale sludge steam drying machine comprising a steam circulation channel as claimed in any one of claims 1 to 9, further comprising a rotatable housing (4) and a drum (3) rotating in synchronism with the housing (4), characterized in that The first steam circulation mechanism (1) and the second steam circulation mechanism (2) are located on the inner and outer sides of the dryer cylinder (3), respectively; each of the air passages (11) is formed by two adjacent partitions (12) dividing the space between the shell (4) and the cylinder (3).

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