CN212222785U

CN212222785U - Sludge drying device

Info

Publication number: CN212222785U
Application number: CN202020787146.6U
Authority: CN
Inventors: 黄亚继; 胡华军; 郭宏伟; 罗健威; 丁守一; 戚二兵; 樊聪慧
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2020-05-13
Filing date: 2020-05-13
Publication date: 2020-12-25
Anticipated expiration: 2030-05-13

Abstract

The utility model discloses a sludge drying device, which comprises a tubular shell with a hollow structure, wherein a hollow jacket which is coaxial with the tubular shell is fixedly sleeved outside the tubular shell, an annular channel is reserved between the hollow jacket and the tubular shell, a stirring shaft with a hollow structure which is coaxial with the tubular shell is arranged at the axis of the tubular shell, two ends of the stirring shaft extend out of the tubular shell, and the stirring shaft is connected with the tubular shell through a bearing; the fixed welding of inner chamber intermediate position department of tube-shape casing has the baffle, and the baffle is divided into crushing district and drying zone with the inner space of tube-shape casing, and the interval is provided with the multiunit stirring unit on the (mixing) shaft in crushing district. The device adopts the internal and external combined heating type mode that the sludge is indirectly heated by the condensation of the water vapor in the stirring shaft and the annular channel and the heat release wall surface and is mixed with the high-temperature flue gas and the wet sludge in the cylindrical shell for direct contact heating, thereby ensuring the efficiency of sludge drying, being flexible to control and having good heat utilization effect.

Description

Sludge drying device

Technical Field

The utility model relates to a sludge drying handles technical field, concretely relates to sludge drying device.

Background

Along with the continuous acceleration of the urbanization process in China, the treatment capacity and treatment rate of urban sewage are continuously improved, and the yield of urban sludge which is a main byproduct of sewage treatment is also rapidly increased. As the municipal sludge treatment in China starts late, key technical equipment is relatively lagged behind, and a large amount of municipal sludge is not properly treated. The sludge is a byproduct in the sewage treatment process, the water content is as high as 95-98%, the water content of sludge discharged by a domestic mechanical dehydration mode is about 80%, and the sludge has high water content, so that the sludge has large stacking area and high transportation cost;

the burning method has obvious reduction effect, saves land, can also eliminate various pathogens and convert toxic and harmful substances into harmless substances. The sludge moisture content is high, only can send into the burning furnace and burn after drying process earlier, and the drying process heat absorption and burn and release heat, and two processes have independently wasted a large amount of energy, utilize the waste heat energy of burning process flue gas to the desicator in being worth noticing.

In recent years, various sludge drying facilities have been developed, and a drum dryer, a fluidized bed dryer, or the like is often used for sludge drying. Like the sludge drying device disclosed in chinese utility model patents CN105486047A, CN208000029U, etc. using the drum type, the drum type dryer mainly has the following technical problems: firstly, due to the rotation of the shell, the air tightness is poor, the possibility of deflagration generation during the drying of the sludge with high volatile content is increased, and potential safety hazards exist; secondly, in order to increase the gas retention time and ensure the drying effect, the device has large diameter and length, heavy equipment, large equipment cost, high heat dissipation loss and low drying heat efficiency; thirdly, the waste heat cannot be used for indirectly heating the sludge due to the rotation of the shell, so that the drying heat efficiency is improved, and the investment and the operating cost are reduced. Like the fluidized bed dryer disclosed in chinese utility model patent CN202836066U, the sealing performance is better than that of the drum dryer, but the airflow resistance is large and the operation cost is high.

The existing rake type drying machines are mainly dependent on the wall surface heat conduction function as disclosed in CN203642625U and CN204693987U, the heat efficiency is low, and the energy consumption for drying sludge is high; intermittent operation is mostly adopted, continuous operation cannot be realized, and the operation cost is increased; the device has poor sealing performance, and has safety risk when drying sludge with high volatile content; in a sludge drying viscous area, the heat and mass transfer resistance is increased sharply, the heat efficiency of the dryer is low, and the power consumption of the dryer is increased. The contact time of the material and the drying medium is short, the sludge treatment capacity is small, the size of the dryer needs to be increased for increasing the treatment capacity and reducing the water content of the product, and the cost is correspondingly increased. The disc dryer disclosed in the patent CN209166051U has the problems that sludge is easily stuck in the dryer, the shearing and crushing effects of sludge are poor, the sticking and blocking effects of sludge in the disc dryer during actual operation are poor, the area of the disc is large, and the cost is high.

SUMMERY OF THE UTILITY MODEL

Utility model purpose: the utility model aims at providing a sludge drying device, which has high drying efficiency, low water content of discharged sludge and small through-flow resistance, achieves the environment-friendly treatment principle of reduction and harmlessness, realizes resource utilization in the follow-up process, and realizes that the heat generated by sludge incineration returns to the drying device in the form of hot flue gas and superheated steam, thereby fully utilizing the energy; the problem of current sludge drying equipment gas tightness relatively poor, drying heat efficiency is low, can't utilize waste heat to carry out indirect heating to mud and lead to the sludge drying energy consumption high is solved.

The technical scheme is as follows: the utility model relates to a sludge drying device, including the tubular casing of hollow structure, the outside fixed cover of tubular casing is equipped with the hollow jacket that sets up with the tubular casing with the axle center, leave annular channel between hollow jacket and the tubular casing, the axle center department of tubular casing installs the (mixing) shaft of hollow structure with the tubular casing with the axle center, both ends of (mixing) shaft all stretch out outside the tubular casing and be connected through the bearing between (mixing) shaft and the tubular casing;

the inner chamber intermediate position department fixed welding of tube-shape casing has the baffle, the baffle divide into crush zone and drying zone with tube-shape casing's inner space, the interval is provided with multiunit stirring unit on the (mixing) shaft in crush zone, and the spacing distance between the adjacent stirring unit increases gradually, the stirring unit all includes two sets of rake teeth that are central symmetry distribution along the (mixing) shaft central line, the rake teeth all inclines to set up, and the rake teeth communicates with each other with the inside of (mixing) shaft fixed connection and rake teeth, fixed mounting has the flight on the (mixing) shaft of drying zone, fixed welding has the discharge gate sideboard of vertical setting on the one end inner wall that tube-shape casing is close to the flight.

Further, adjacent stirring units are arranged in a staggered mode; and a plurality of groups of mud scrapers are fixedly arranged on the spiral piece, and a gap is formed between the mud scrapers and the inner wall of the cylindrical shell. The stirring unit has the effect of crushing, guiding and propelling when rotating, and the mud scraper can avoid the influence of the inner wall mud of the cylindrical shell on the heat transfer efficiency.

Furthermore, a plurality of groups of jacket clapboards which are arranged at intervals are arranged in the annular channel between the hollow jacket and the cylindrical shell, and the opening directions of the adjacent jacket clapboards are opposite and are arranged in a vertically staggered manner to form an S-shaped flow channel. The S-shaped flow channel increases the stroke of water vapor and improves the drying efficiency.

Furthermore, a gap is arranged at the bottom of the jacket clapboard with an upward opening in the jacket clapboard in the annular channel corresponding to the cylindrical shell drying area. The notches prevent the accumulation of liquid water.

Furthermore, one end of an annular channel between the hollow jacket and the cylindrical shell is provided with a first steam inlet, and the other end of the annular channel is provided with a first steam outlet; and a second steam inlet is formed at one end of the stirring shaft, and a second steam outlet is formed at the other end of the stirring shaft. Wet sludge is indirectly heated by water vapor in the stirring shaft and the cavity in the rake teeth and water vapor in the annular channel between the hollow jacket and the cylindrical shell, so that the drying efficiency is increased.

Furthermore, a feed inlet communicated with the inside of the cylindrical shell is formed in one end, close to the rake teeth, of the cylindrical shell, and a discharge outlet communicated with the inside of the cylindrical shell is formed in one end, far away from the rake teeth, of the cylindrical shell.

Furthermore, one end of the cylindrical shell, which is close to the rake teeth, is provided with a high-temperature flue gas inlet communicated with the interior of the cylindrical shell, and the high-temperature flue gas inlet is arranged in a tangent manner with the outer wall of the cylindrical shell; and one end of the cylindrical shell, which is far away from the rake teeth, is provided with a high-temperature flue gas outlet communicated with the inside of the cylindrical shell, and the high-temperature flue gas outlet is arranged in a tangent manner with the outer wall of the cylindrical shell. The air inlet direction is set to be a tangential form, and the resistance is small.

Furthermore, a plurality of holes for connecting the crushing area and the drying area are arranged on the baffle. The baffle can be arranged in various types, such as a ring shape, a small hole shape and a fan blade shape, and the amount of the materials entering the drying area is controlled by changing the hole area.

Furthermore, an included angle between the rake teeth and the axial line of the stirring shaft is 20-30 degrees; the stagger angle between adjacent stirring units is 90 degrees. The rake teeth have the functions of crushing, guiding and propelling when rotating.

Furthermore, both ends of the cylindrical shell are sealed by flanges, and a sealing ring is arranged between the flanges at both ends of the cylindrical shell. The sealing performance of the device is improved.

Has the advantages that: compared with the prior art, the utility model has the advantages of:

(1) compared with a single heat source dryer, the device can indirectly heat sludge by the condensation of the stirring shaft and the water vapor in the annular channel and the heat release wall surface, and is in an internal and external combined heating type form of mixing and directly contacting and heating with high-temperature flue gas and wet sludge in the cylindrical shell, thereby ensuring the efficiency of sludge drying, supplying heat by internal and external combination, being flexible to control and having good heat utilization effect;

(2) compared with a rake dryer, the device is axially divided into a crushing area and a drying area, adopts partition board division, adopts a form of combining rake teeth and a spiral piece, combines with a drying actual flow, ensures the crushing fineness and the drying efficiency of sludge, and has smaller resistance of a drying medium in the drying device and stable operation of the drying device;

(3) compared with a disc type dryer, the disc type dryer has the advantages that flue gas is adopted for direct drying, the drying speed is high, water in sludge enters the flue gas, a water treatment system does not need to be added in a sludge drying system, and the sludge drying degree is higher than that of the disc type dryer.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a front view of the cylindrical housing;

FIG. 3 is a schematic view of a hollow jacket structure;

FIG. 4 is a front view of a hollow jacket;

FIG. 5 is a diagram of three versions of a baffle;

FIG. 6 is a cross-sectional view of a flight;

fig. 7 is a schematic view of a rake tooth structure;

fig. 8 is a side view of fig. 7.

Detailed Description

The invention will be further described with reference to the following figures and examples:

as shown in fig. 1 to 8, the utility model relates to a sludge drying device, including hollow structure's cylindrical shell 1, cylindrical shell 1 is the fixed part, the outside fixed cover of cylindrical shell 1 is equipped with the hollow jacket 2 that sets up with cylindrical shell 1 with the axle center, leave annular channel 3 between hollow jacket 2 and the cylindrical shell 1, the axle center department of cylindrical shell 1 installs the (mixing) shaft 4 with the hollow structure of cylindrical shell 1 with the axle center, both ends of (mixing) shaft 4 all stretch out outside cylindrical shell 1 and be connected through the bearing between (mixing) shaft 4 and the cylindrical shell 1, both ends of cylindrical shell 1 are all sealed through ring flange 5, be equipped with sealing washer 6 between the ring flange 5 of both ends of cylindrical shell 1, improve the leakproofness of device; the two ends of the stirring shaft 4 are provided with shaft heads which are supported by two supporting bearing seats 7 and are connected with a variable frequency motor 10 through a coupler 8 and a gear reducer 9, and the stirring shaft 4 is driven to rotate by the variable frequency motor 10;

the middle position of the inner cavity of the cylindrical shell 1 is fixedly welded with a baffle plate 11, the baffle plate 11 divides the inner space of the cylindrical shell 1 into a crushing area 12 and a drying area 13, the baffle plate 11 enables sludge to be fully crushed in the crushing area 12 before entering the drying area 13, the baffle plate 11 is provided with a plurality of holes for connecting the crushing area 12 and the drying area 13, the baffle plate 11 can be arranged in various types, such as an A-ring type, a B-small hole type (black points in B in figure 5 are holes) and a C-fan blade type, and the amount of the materials entering the drying area 13 is controlled by changing the area of the holes;

the stirring shaft 4 is divided into a crushing area 12 and a drying area 13, the front section and the rear section are divided into a crushing area 12 and a drying area 13, a plurality of groups of stirring units 14 are arranged on the stirring shaft 4 of the crushing area 12 at intervals, the interval distance between every two adjacent stirring units 14 is gradually increased, the adjacent stirring units 14 are arranged in a staggered mode, the staggered angle between every two adjacent stirring units 14 is 90 degrees, each stirring unit 14 comprises two groups of rake teeth 141 which are distributed along the central line of the stirring shaft 4 in a central symmetry mode, the rake teeth 141 are all arranged in an inclined mode, the included angle between each rake tooth 141 and the axial line of the stirring shaft 4 is 20-30 degrees, the rake teeth 141 are; the rake teeth 141 are densely and sparsely arranged, the rake teeth 141 rotate to crush and drive the materials to turn over, and the materials can axially move under the action of crushing, guiding and propelling during rotation;

a spiral blade 15 is fixedly arranged on the stirring shaft 4 of the drying area 13, a plurality of groups of mud scrapers 16 are fixedly arranged on the spiral blade 15, and a gap is formed between the mud scrapers 16 and the inner wall of the cylindrical shell 1; the mud scraper 16 can avoid the influence of the mud on the inner wall of the cylindrical shell 1 on the heat transfer efficiency; the spiral piece 15 can fully dry the materials and convey the materials to the discharge port 25, and a vertically arranged discharge port baffle plate 17 is fixedly welded on the inner wall of one end of the cylindrical shell 1 close to the spiral piece 15; the discharge port 25 is provided with a discharge port baffle plate 17, and the discharge amount of the dry sludge is controlled by adjusting the height of the discharge port baffle plate 17, so that the retention time of the sludge in the reactor is controlled, and the purpose of controlling the water content of the dry sludge is achieved;

a plurality of groups of jacket clapboards 18 arranged at intervals are arranged in the annular channel 3 between the hollow jacket 2 and the cylindrical shell 1, and the opening directions of the adjacent jacket clapboards 18 are opposite and are staggered up and down to form an S-shaped flow channel, so that the S-shaped flow channel increases the stroke of water vapor and improves the drying efficiency; wherein, the bottom of the jacket clapboard 18 with an upward opening direction in the jacket clapboard 18 in the annular channel 3 corresponding to the drying area 13 of the cylindrical shell 1 is provided with a gap 19, the gap 19 can prevent the accumulation of liquid water, and the heat is condensed and released in the annular channel 3 corresponding to the drying area 13 of the cylindrical shell 1 by controlling the convection heat release of water vapor in the annular channel 3 corresponding to the crushing area 12 of the cylindrical shell 1 and adapting to the sectional form of the drying crushing area 12 and the drying area 13;

one end of an annular channel 3 between the hollow jacket 2 and the cylindrical shell 1 is provided with a first steam inlet 20, and the other end of the annular channel 3 is provided with a first steam outlet 21; one end of the stirring shaft 4 is provided with a second steam inlet 22, and the other end of the stirring shaft 4 is provided with a second steam outlet 23; the first steam inlet 20 and the second steam inlet 22 are both filled with high-temperature steam, and steam-water separators are arranged at the first steam outlet 21 and the second steam outlet 23 for steam-water separation; the wet sludge is indirectly heated by the water vapor in the stirring shaft 4 and the cavities in the rake teeth 141 and the water vapor in the annular channel 3 between the hollow jacket 2 and the cylindrical shell 1, so that the drying efficiency is increased;

one end of the cylindrical shell 1 close to the rake teeth 141 is provided with a feed inlet 24 communicated with the interior of the cylindrical shell 1, and one end of the cylindrical shell 1 far away from the rake teeth 141 is provided with a discharge outlet 25 communicated with the interior of the cylindrical shell 1; the cylindrical shell 1 is also provided with an access hole 28 communicated with the inside of the cylindrical shell 1;

one end of the cylindrical shell 1 close to the rake teeth 141 is provided with a high-temperature flue gas inlet 26 communicated with the interior of the cylindrical shell 1, and the high-temperature flue gas inlet 26 is tangential to the outer wall of the cylindrical shell 1; one end of the cylindrical shell 1, which is far away from the rake teeth 141, is provided with a high-temperature flue gas outlet 27 communicated with the interior of the cylindrical shell 1, the high-temperature flue gas outlet 27 is arranged in a tangential manner with the outer wall of the cylindrical shell 1, the air inlet direction is arranged in a tangential manner, and the resistance is small; the stirring shaft 4 is a rotor and drives rake teeth 141 and a spiral plate 15 arranged on the rotor to rotate, high-temperature flue gas is introduced into a high-temperature flue gas inlet 26, the high-temperature flue gas enters the cylindrical shell 1 tangentially, and enters the cylindrical shell 1 tangentially to be contacted with material particles, the material is fully mixed with hot flue gas for drying in the crushing, stirring and conveying processes of the rake teeth 141, fine particle materials are further dried on the spiral plate 15 and then conveyed to a discharge port 25, the discharge port 25 is provided with a discharge port baffle plate 17, and the dry sludge discharge amount is controlled by adjusting the height of the discharge port baffle plate 17, so that the residence time of sludge in the reactor is controlled, and the purpose of controlling the water content of the dry sludge; the flue gas advances along the spiral channel in the drying area 13, can fully contact with the sludge, and the through-flow resistance is small, the waste gas is discharged from the high-temperature flue gas outlet 27, meanwhile, the high-temperature water vapor is condensed in the stirring shaft 4 with the hollow structure and the annular channel 3 between the hollow jacket 2 and the cylindrical shell 1 to provide partial heat for drying the sludge in the cylindrical shell 1, the drying efficiency is high, the stable and continuous operation can be realized, and the energy consumption for disposal is low;

the whole device adopts an internal and external combined heating type mode that the sludge is indirectly heated by the water vapor condensation heat release wall surface in the stirring shaft 4 and the annular channel 3 and is mixed with the high-temperature flue gas and the wet sludge in the cylindrical shell 1 to be directly contacted and heated, so that the effect of internal and external combined heating is achieved; wet sludge is fed into the cylindrical shell 1 through the feed inlet 24, is firstly contacted with high-temperature flue gas, then enters the crushing area 12, is continuously crushed, overturned and conveyed rightwards by the rake teeth 141, is fully mixed with hot flue gas in the cylindrical shell 1, and is indirectly heated by water vapor in the stirring shaft 4 and cavities in the rake teeth 141 and water vapor in the annular channel 3; the mud fine particle enters into drying zone 13 and is carried right by flight 15, thereby hot flue gas and fine particle exist the moisture in the bigger heat transfer area continuation heating fine particle, simultaneously (mixing) shaft 4 and the vapor condensation in the annular channel 3 supply with mud drying for the more heat of water release, the effect and the efficiency of mud drying have been guaranteed, then dry mud particle discharge gate 25 output, by discharge gate sideboard 17 control ejection of compact mud water content, 1 inside waste gas of tube-shape casing is discharged through high temperature flue gas outlet 27 tangential.

Example 1

One embodiment is that wet sludge with water content above 80% is selected as the material to be dried, 350 ℃ high temperature hot flue gas enters tangentially from a high temperature flue gas inlet 26, 0.6Mpa and 200 ℃ superheated steam is introduced into the inside of a stirring shaft 4 and an annular channel 3 in the device, the high temperature hot flue gas comes from one part of the flue gas at the outlet of a hearth for dry sludge incineration, the superheated steam is generated by a flue gas heating waste heat boiler for sludge incineration, the material uniformly falls into the inside of a cylindrical shell 1 through a double-roll extruder above a feed inlet 24 of the cylindrical shell 1, the material is crushed, stirred and transported rightwards by a rotating rake tooth 141, meanwhile, the material is heated by water vapor through a wall surface and is directly contacted and heated by the hot flue gas, sludge blocks with insufficient crushing degree are blocked by a small-hole baffle plate 11 and cannot smoothly enter a drying area 13, and are further crushed by the rake tooth 141, the rake, the included angle between the stirring shaft 4 and the axial line is 20 degrees, and the rotating speed of the stirring shaft 4 is about 20 r/min; the fine-particle sludge is mainly dried on the spiral piece 15 and is conveyed to the right end, the water vapor in the region is condensed in the annular channel 3 and is conducted to the sludge, the dry sludge particles are conveyed to the discharge port 25 by the spiral piece 15, part of dry sludge particles carried in the tangential traveling of the flue gas in the drying zone 13 naturally fall back, the dry sludge is finally discharged from the discharge port 25, the discharge amount of the dry sludge is controlled by adjusting the height of the discharge port baffle plate 17, and is conveyed to a storage bin by a belt, the waste gas contains few dust particles and is tangentially discharged from a high-temperature flue gas outlet 27 (an inertia separation plate and a filter can be additionally arranged at the high-temperature flue gas outlet 27 to prevent the sludge particles from drifting out of the high-temperature flue gas outlet 27 along with the waste gas), water condensed by water vapor is discharged from a first steam outlet 21 and a second steam outlet 23, the temperature of dry sludge at a discharge port 25 is about 70 ℃, and the temperature of condensed water at the first steam outlet 21 and the second steam outlet 23 is about 150 ℃. The water content of the dry sludge is controlled within the range of 5-30% by adjusting the frequency of the variable frequency motor 10 and the height of the discharge port baffle plate 17.

Example 2

One embodiment is that wet sludge with water content above 80% is selected as the material to be dried, high temperature hot flue gas at 350 ℃ enters tangentially from a high temperature flue gas inlet 26, the high temperature hot flue gas comes from a part of flue gas at the outlet of a hearth where dry sludge is burned, superheated steam is generated by a flue gas heating waste heat boiler of the sludge burning, the material is continuously fed into the cylindrical shell 1 through a feed inlet 24, the material is crushed by a rotating rake tooth 141, stirred and transported rightwards, the high temperature flue gas directly contacts and heats the material sludge, water vapor indirectly heats the material sludge through the wall surface, sludge blocks with insufficient crushing degree are blocked by a fan blade type baffle plate 11 and cannot smoothly enter a drying area 13, and then are continuously crushed by the rake tooth 141, the rake tooth 141 is fixed on a stirring shaft 4, the included angle with the axial line of the stirring shaft 4 is 30 degrees, the rotating speed of the stirring shaft 4 is about 15r/min, fine-particle sludge is mainly, conveying to the right end, conveying dry sludge particles to a discharge port 25 by a spiral sheet 15, returning part of dry sludge particles carried by smoke to the cylindrical shell 1 in rotation, tangentially discharging waste gas from a high-temperature smoke gas outlet 27, finally discharging dry sludge from the discharge port 25, adjusting the height of a discharge port baffle plate 17 to control the discharge amount of the dry sludge, conveying the dry sludge to a storage bin by a belt, discharging less dust particles contained in the waste gas from the gas outlet (a cyclone dust collector can be additionally arranged at the high-temperature smoke gas outlet 27 to more thoroughly settle the sludge particles in the waste gas), controlling the temperature of the dry sludge at the discharge port 25 to be about 70 ℃, and controlling the water content of the dry sludge to be within the range of 5-30% by adjusting the frequency of a variable frequency motor 10 and the height of the discharge port baffle plate 17.

Claims

1. A sludge drying device is characterized in that: the stirring device comprises a cylindrical shell with a hollow structure, wherein a hollow jacket which is coaxial with the cylindrical shell is fixedly sleeved outside the cylindrical shell, an annular channel is reserved between the hollow jacket and the cylindrical shell, a stirring shaft with a hollow structure and coaxial with the cylindrical shell is installed at the axis of the cylindrical shell, two ends of the stirring shaft extend out of the cylindrical shell, and the stirring shaft is connected with the cylindrical shell through a bearing;

2. The sludge drying apparatus according to claim 1, wherein: the adjacent stirring units are arranged in a staggered manner; and a plurality of groups of mud scrapers are fixedly arranged on the spiral piece, and a gap is formed between the mud scrapers and the inner wall of the cylindrical shell.

3. The sludge drying apparatus according to claim 1, wherein: and a plurality of groups of jacket clapboards arranged at intervals are arranged in the annular channel between the hollow jacket and the cylindrical shell, and the opening directions of the adjacent jacket clapboards are opposite and are arranged in a vertically staggered manner to form an S-shaped flow channel.

4. The sludge drying apparatus as claimed in claim 3, wherein: and a gap is arranged at the bottom of the jacket clapboard with an upward opening in the jacket clapboard in the annular channel corresponding to the cylindrical shell drying area.

5. The sludge drying apparatus according to claim 1, wherein: a first steam inlet is formed at one end of an annular channel between the hollow jacket and the cylindrical shell, and a first steam outlet is formed at the other end of the annular channel; and a second steam inlet is formed at one end of the stirring shaft, and a second steam outlet is formed at the other end of the stirring shaft.

6. The sludge drying apparatus according to claim 1, wherein: and a feed inlet communicated with the interior of the cylindrical shell is formed in one end, close to the rake teeth, of the cylindrical shell, and a discharge outlet communicated with the interior of the cylindrical shell is formed in one end, far away from the rake teeth, of the cylindrical shell.

7. The sludge drying apparatus as claimed in claim 6, wherein: one end of the cylindrical shell, which is close to the rake teeth, is provided with a high-temperature flue gas inlet communicated with the interior of the cylindrical shell, and the high-temperature flue gas inlet is arranged in a tangent manner with the outer wall of the cylindrical shell; and one end of the cylindrical shell, which is far away from the rake teeth, is provided with a high-temperature flue gas outlet communicated with the inside of the cylindrical shell, and the high-temperature flue gas outlet is arranged in a tangent manner with the outer wall of the cylindrical shell.

8. The sludge drying apparatus according to claim 1, wherein: the baffle is provided with a plurality of holes for connecting the crushing area and the drying area.

9. The sludge drying apparatus according to claim 2, wherein: the included angle between the rake teeth and the axial line of the stirring shaft is 20-30 degrees; the stagger angle between adjacent stirring units is 90 degrees.

10. The sludge drying apparatus according to claim 1, wherein: the two ends of the cylindrical shell are sealed through flanges, and sealing rings are arranged between the flanges at the two ends of the cylindrical shell.