CN215676378U

CN215676378U - External combustion type rotary kiln

Info

Publication number: CN215676378U
Application number: CN202121396234.4U
Authority: CN
Inventors: 姚胜铎
Original assignee: Xiaoyue Technology Beijing Co ltd
Current assignee: Xiaoyue Technology Beijing Co ltd
Priority date: 2021-06-23
Filing date: 2021-06-23
Publication date: 2022-01-28
Anticipated expiration: 2031-06-23

Abstract

The utility model relates to an external combustion type rotary kiln, which comprises a charging hopper, a screw feeder, a rotary drum, a driving part, a heating furnace, a discharging device, a roller sealer, a combustion-supporting air heat exchanger and an extraction pipe, wherein the charging hopper is erected at the feeding end of the screw feeder; the length direction of the rotary drum is horizontal or inclined, and one end of the rotary drum is rotatably connected with the discharge end of the screw feeder; the driving component is arranged on one side of the rotary drum to drive the rotary drum to rotate; the heating furnace is erected outside the rotary drum, and the temperature in the heating furnace is between 700 and 1350 ℃; the other end of the rotary drum is rotationally connected with a discharging device; the two groups of roller sealers are respectively and fixedly connected on the screw feeder and the discharging device, and the roller sealers are tightly attached to the outer wall of the rotary drum; the combustion-supporting air heat exchanger is erected at the top of the heating furnace and communicated with the heating furnace; the extracting pipe is arranged on one side of the discharging device and used for pumping out carbon dioxide gas, and the utility model has the advantages of improving the calcining efficiency of the rotary kiln and improving the yield of the carbon dioxide gas.

Description

External combustion type rotary kiln

Technical Field

The utility model relates to the technical field of calcining equipment, in particular to an external combustion type rotary kiln.

Background

The rotary kiln is a rotary calcining kiln, commonly called a rotary kiln, and is a thermal equipment for completing high-temperature heat treatment of raw materials in a rotary cylinder. Raw materials are arranged in the obliquely arranged cylinder, under the action of gravity and the drive of the rotary cylinder, the raw materials roll and advance from a high end (kiln tail) to a low end (kiln head), fuel is fed into the cylinder from the low end to be combusted, generated flue gas flows to the high end, the flue gas and the raw materials move in opposite directions, and heat exchange is carried out between the flue gas and the raw materials in the flowing process of the high-temperature flue gas, so that the raw materials are calcined.

Most of the existing rotary kilns are not high in heat transfer efficiency due to long length, and in order to avoid overhigh local temperature of a kiln body, the temperature of flame sprayed by a burner is not high particularly, and if more mineral aggregates enter the rotary kiln, the problem of insufficient calcination of the mineral aggregates can be solved. If the amount of the mineral aggregate put in is small, the production efficiency is also reduced.

Therefore, in view of the above disadvantages, it is desirable to provide an external combustion rotary kiln.

SUMMERY OF THE UTILITY MODEL

Technical problem to be solved

The utility model aims to solve the technical problems of poor heat transfer efficiency and low production efficiency of the traditional rotary kiln.

(II) technical scheme

In order to solve the technical problem, the utility model provides an external combustion type rotary kiln which comprises a feeding hopper, a screw feeder, a rotary drum, a driving part, a heating furnace, a discharging device, a roller sealer, a combustion-supporting air heat exchanger and an extraction pipe, wherein the feeding hopper is erected at the feeding end of the screw feeder to enable materials in the feeding hopper to move towards the screw feeder; the rotary drum is a cylindrical drum body, the length direction of the rotary drum is horizontal or inclined, and one end of the rotary drum is rotatably connected to the discharge end of the screw feeder so that the materials enter the rotary drum; the driving component is arranged on one side of the rotary drum to drive the rotary drum to rotate; the heating furnace is erected outside the rotary drum, and the temperature in the heating furnace is between 700 and 1350 ℃; the other end of the rotary drum is rotationally connected with a discharging device; the two groups of roller sealers are respectively and fixedly connected on the screw feeder and the discharging device, and the roller sealers are tightly attached to the outer wall of the rotary drum; the combustion-supporting air heat exchanger is erected at the top of the heating furnace and communicated with the heating furnace; the extraction pipe is arranged on one side of the discharging device and used for pumping out carbon dioxide gas.

As a further explanation of the present invention, preferably, one or more sections of heating furnaces are distributed along the length direction of the revolving drum, the revolving drum between adjacent sections of heating furnaces is fixedly connected with a supporting rolling ring, the outer diameter of the supporting rolling ring is larger than the outer diameter of the revolving drum, the bottom of the supporting rolling ring is abutted with a plurality of groups of rollers, the rollers are rotatably connected to a wheel carrier, and the wheel carrier is fixed on the ground.

As a further explanation of the present invention, preferably, a smoke passing pipe is installed between the adjacent sections of the heating furnaces at the top, and two ends of the smoke passing pipe are respectively communicated with the adjacent sections of the heating furnaces.

As a further explanation of the present invention, preferably, the air inlet end of the combustion-supporting air heat exchanger is fixedly connected with a smoke exhaust pipe, two ends of the smoke exhaust pipe are respectively communicated with the combustion-supporting air heat exchanger and the heating furnace, the smoke exhaust pipe and the smoke through pipe are respectively provided with a shock absorber at the air inlet end, and the shock absorber is a corrugated pipe with a triangular bent end.

As a further explanation of the present invention, preferably, the heating furnace is made of a heat insulating material, a furnace chamber is arranged between the middle part of the heating furnace and the rotating drum, and two ends of the heating furnace are abutted against the outer wall surface of the rotating drum; the heating furnace is provided with a plurality of groups of burners at one side of the bottom of the furnace chamber, combustible gas is introduced into the burners, and the outer ports of the burners ignite the gas to generate heat to heat the rotary drum.

As a further explanation of the present invention, preferably, a kiln body sealer is fixedly connected between adjacent sections of the heating furnace, the kiln body sealer is an annular structure made of a heat insulating material, two end ports of the kiln body sealer protrude from outer walls of the kiln body sealer, a cross section of a protruding end is trapezoidal, the protruding end of the kiln body sealer is embedded into the heating furnace, and an inner end surface of the kiln body sealer is abutted against an outer wall of the rotary drum.

As a further explanation of the present invention, preferably, a plurality of sets of burners are distributed at intervals along the length direction of the rotating drum, the heights of the plurality of sets of burners are all lower than the height of the rotating drum, a plurality of air pipes are surrounded around the burners at intervals, and oxygen is introduced into the air pipes.

As a further explanation of the utility model, preferably, the top of the screw feeder is provided with an air-receiving opening, and the air-receiving opening is connected with an air pump; a filter screen is arranged below the air collecting port; the bottom of the spiral feeder is provided with a slag discharge pipe, and the filter screen is positioned above the slag discharge pipe.

As a further description of the present invention, preferably, the driving component includes a driving motor, a speed reducer, a driving gear and a driven gear, the driving motor and the speed reducer are both fixedly connected to the ground or the ground platform, an output end of the driving motor is fixedly connected to an input end of the speed reducer, an output end of the speed reducer is fixedly connected to the driving gear, the driven gear is fixedly connected to the drum, an axis of the driven gear coincides with an axis of the drum, and the driving gear is engaged with the driven gear.

As a further description of the present invention, preferably, the roller sealer is an annular structure formed by a plurality of sets of arc-shaped sheet metal plates, adjacent metal plates are tightly attached to each other, and the inner arc surfaces of the metal plates abut against the outer wall of the drum and are further bent, so that the roller sealer is in contact with the surface of the drum.

(III) advantageous effects

The technical scheme of the utility model has the following advantages:

according to the utility model, by designing a novel heating mode, the rotary drum is uniformly heated, the heat transfer efficiency is improved, the heat reaching the reaction temperature can be accepted by the mineral aggregate in the flowing process of the rotary drum, a larger amount of mineral aggregate can be calcined in the rotary drum at one time, and the production efficiency is improved. Simultaneously under the effect of combustion-supporting wind heat exchanger, reduce the interior waste gas content of furnace chamber, ensure that the fuel can fully burn and release heat, improve energy utilization and rate, retrieve secondary utilization with high temperature waste gas simultaneously, reduce the energy extravagant.

Drawings

FIG. 1 is a diagram of the overall assembly effect of the present invention;

FIG. 2 is an enlarged view of A in FIG. 1;

FIG. 3 is a side view of the present invention;

FIG. 4 is an enlarged view of B in FIG. 3;

FIG. 5 is a rear view of the present invention;

FIG. 6 is a partial cross-sectional view of the present invention;

FIG. 7 is a view showing another arrangement of the heating furnace of the present invention.

In the figure: 1. a hopper; 11. a rack; 2. a screw feeder; 21. a frame; 22. a feed motor; 23. a belt; 24. an air receiving port; 25. a slag discharge pipe; 3. a rotating drum; 31. supporting the rolling ring; 32. a feed pipe; 4. a drive member; 41. a drive motor; 42. a speed reducer; 43. a driving gear; 44. a driven gear; 5. heating furnace; 51. a furnace chamber; 52. burning a nozzle; 53. an air tube; 54. a support plate; 55. a kiln body sealer; 6. a discharging device; 61. a support; 7. a roller sealer; 8. a combustion-supporting air heat exchanger; 81. a smoke exhaust pipe; 82. ventilating a smoke pipe; 83. a shock absorber; 84. an exhaust pipe; 9. and (4) extracting the tube.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

An external combustion type rotary kiln is combined with a graph 1 and a graph 3, and comprises a loading hopper 1, a spiral feeder 2, a rotary drum 3, a driving component 4, a heating furnace 5, a discharging device 6, a roller sealer 7, a combustion-supporting air heat exchanger 8 and an extraction pipe 9, wherein the loading hopper 1 is erected at the feeding end of the spiral feeder 2, one end of the rotary drum 3 is rotatably connected at the discharging end of the spiral feeder 2, and the driving component 4 is erected on one side of the rotary drum 3 to drive the rotary drum 3 to rotate; the heating furnace 5 is erected outside the rotary drum 3, the rotary drum is coated by the heating furnace 5, the coating length is not less than 80% of the total length of the rotary drum 3, and the temperature in the heating furnace 5 is not lower than 700-1350 ℃; the other end of the rotary drum 3 is rotationally connected with a discharging device 6; two groups of roller sealers 7 are respectively fixedly connected on the screw feeder 2 and the discharging device 6, and the roller sealers 7 are tightly attached on the outer wall of the rotary drum 3; the combustion-supporting air heat exchanger 8 is erected at the top of the heating furnace 5 and is communicated with the heating furnace 5; the extraction pipe 9 is arranged on one side of the discharging device 6 and used for extracting carbon dioxide gas.

With reference to fig. 1 and 3, the charging hopper 1 is an inverted quadrangular frustum pyramid shaped shell, the table frame 11 is surrounded around the charging hopper 1, the bottom of the table frame 11 is fixed on the ground, and the table frame 11 is arranged to fix the position of the charging hopper 1. The top of the charging hopper 1 is provided with a feeding hole for receiving the thrown mineral aggregate. The bottom of the charging hopper 1 is provided with a discharging pipe which is communicated with the screw feeder 2. The screw feeder 2 is also an inverted quadrangular frustum pyramid shaped shell, the frame 21 is welded around the screw feeder 2, and the bottom of the frame 21 is fixed on the ground and used for supporting the screw feeder 2. The rack 11 is located the 1 below of loading hopper and is equipped with

feed motor

22, and 2 middle parts of screw feeder rotate and are connected with helical blade, and helical blade middle parts have linked firmly the connecting axle, and connecting axle one end is stretched out screw feeder 2 and is outer and linked firmly the runner, and feed motor 22 output has also linked firmly the runner, and the cover has belt 23 between two runners. The feeding motor 22 rotates to drive the spiral fan blades to rotate by the belt 23, so that the spiral fan blades push the mineral materials into the rotary drum 3 for reaction.

Referring to fig. 3 and 4, an air collecting port 24 is arranged at the top of the screw feeder 2, and an air pump is connected to the air collecting port 24 and used for extracting the original air in the rotary drum 3, and the air is extracted through the air collecting port 24 in the early stage of calcination, so that the air in the rotary drum 3 only contains carbon dioxide. And further ensures that the purity of the extracted carbon dioxide gas is higher when the subsequent extraction pipe 9 extracts the gas. A filter screen is arranged below the air collecting opening 24, and the filter screen is arranged to prevent dust in the rotary drum 3 from being sucked into the air collecting opening 24. 2 bottoms of screw feeder are equipped with scum pipe 25, the filter screen is located scum pipe 25 and helical fan leaf top, and the filter screen can avoid simultaneously inhaling the receipts gas port 24 with the dust mineral aggregate that does not get into in the rotary drum 3, treat gaseous collection completion or the higher back of filter screen jam degree, reverse open the air pump or change the air pump, make the air pump with external air suction screw feeder 2 in, blow off the dust on the filter screen and fall on scum pipe 25, clear away the dust material by scum pipe 25 is unified at last, play the effect of certain clean filter screen.

Referring to fig. 6 and 7, the drum 3 is a cylindrical barrel made of refractory metal, the length direction of the drum 3 is horizontal or inclined, and if the drum 3 is inclined, the drum is inclined towards the lower part of the discharging device 6. The length of the rotary drum 3 is about 7m, and the longer rotary drum 3 can provide longer reaction time for mineral aggregates entering the rotary drum 3, thereby ensuring that the mineral aggregates are fully reacted. One end of the rotary drum 3 close to the screw feeder 2 is fixedly connected with a feeding pipe 32 which is used for being connected with the screw feeder 2. With reference to fig. 1 and 2, the driving part 4 includes a driving motor 41, a speed reducer 42, a driving gear 43 and a driven gear 44, the driving motor 41 and the speed reducer 42 are both fixedly connected to the ground or the ground, an output end of the driving motor 41 is fixedly connected to an input end of the speed reducer 42, an output end of the speed reducer 42 is fixedly connected to the driving gear 43, the driven gear 44 is fixedly connected to the drum 3, an axis of the driven gear 44 is coincident with an axis of the drum 3, and the driving gear 43 is engaged with the driven gear 44. Rotate through driving motor 41, make driving gear 43 drive driven gear 44 drive rotary drum 3 and rotate, make rotary drum 3 can mix the mineral aggregate, will be located the mineral aggregate of rotary drum 3 bottom and raise, ensure all mineral aggregate homoenergetic thermal reaction, further improve reaction efficiency, avoid extravagant.

Referring to fig. 1 and 5, the heating furnace 5 is made of heat insulating materials, and is generally made of a plurality of heat insulating bricks to be a cylinder or a square, a support plate 54 is arranged at the bottom of the heating furnace 5, the support plate 54 is connected with a plurality of platforms, the heat insulating bricks are placed on the whole support plate 54 to build the heating furnace 5, and the platforms can stably support the heating furnace 5. Referring to fig. 6, a furnace chamber 51 is disposed between the middle of the heating furnace 5 and the drum 3, and two ends of the heating furnace 5 are abutted against the outer wall of the drum 3, so that the furnace chamber 51 forms a relatively closed space to prevent energy loss due to heat leakage. The heating furnace 5 is provided with a plurality of groups of burners 52 at one side of the bottom of the furnace chamber 51, combustible gas is introduced into the burners 52, and the outer ports of the burners 52 ignite the gas to generate heat to heat the rotating drum 3. Through distributing multiunit nozzle 52 along 3 length direction of rotary drum, can carry out the even heating to rotary drum 3, avoid producing local overheated problem, the guarantee heats mineral aggregate comprehensively, can also put into more mineral aggregates in to rotary drum 3 simultaneously to improve production efficiency. The 3 length direction interval distributions of rotary drum are followed to multiunit nozzle 5, and multiunit nozzle 5 highly all is less than the 3 heights of rotary drum, and nozzle 5 interval all around encloses a plurality of trachea 53, and trachea 53 intussuseption has oxygen.

With reference to fig. 5 and 6, a kiln body sealer 55 is fixedly connected between adjacent sections of the heating furnace 5, the kiln body sealer 55 is of an annular structure made of heat-insulating materials, the outer walls of two ports of the kiln body sealer 55 protrude, the cross section of the protruding end is trapezoidal, the protruding end of the kiln body sealer 55 is embedded into the heating furnace 5, the inner end face of the kiln body sealer 55 is abutted against the outer wall of the rotary drum 3, and the kiln body sealer 55 is arranged to prevent the rotary drum 3 from being heated unevenly and deforming due to temperature reduction of the exposed part of the rotary drum 3.

Referring to fig. 6 and 7, the heating furnace 5 may be distributed along the length of the drum 3 in one or more sections. Wherein when 3 length of rotary drum are longer, then interval distribution multistage heating furnaces 5 to link firmly on the rotary drum 3 between adjacent section heating furnaces 5 and support and roll the circle 31, support and roll the circle 31 external diameter and be greater than the 3 external diameters of rotary drum, support and roll the circle 31 bottom butt and have the multiunit running roller, the running roller rotates and connects on the wheel carrier, the wheel carrier is fixed subaerial, additionally supports rotary drum 3 through running roller and wheel carrier, avoids 3 middle parts of rotary drum to sink and influence and rotate the axiality, and guarantee rotary drum 3 can work for a long time safety and stability. When the length of the rotary drum 3 is short, the heating furnace 5 is used for one section, the supporting rolling ring 31 and the like are not required to be installed, and the maximum heat transfer efficiency of the rotary drum 3 can be guaranteed.

With reference to fig. 3 and 5, the discharging device 6 is a square shell, the support 61 is surrounded around the discharging device 6, the bottom of the support 61 is fixed on the ground and used for supporting the discharging device 6, and the discharge hole is formed in the bottom of the discharging device 6, so that the calcined mineral aggregate can be discharged, and the subsequent waste heat recovery and utilization can be conveniently carried out. The roller sealer 7 is of an annular structure formed by a plurality of groups of arc-shaped flaky metal plates in a surrounding mode, the metal plates are adjacent to each other and tightly attached to each other, the inner arc surfaces of the metal plates are abutted against the outer wall of the rotary drum 3 and further bent, so that the roller sealer 7 is in surface contact with the rotary drum 3, mineral aggregate can be prevented from leaking, the rotation of the rotary drum 3 is not influenced, and two purposes are achieved at one stroke.

Referring to fig. 5 and 6, the air inlet end of the combustion-supporting air heat exchanger 8 is fixedly connected with a smoke exhaust pipe 81, and two ends of the smoke exhaust pipe 81 are respectively communicated with the combustion-supporting air heat exchanger 8 and the heating furnace 5. When the multi-section heating furnace 5 is adopted, the smoke passing pipe 82 is erected at the top between the adjacent sections of the heating furnace 5, two ends of the smoke passing pipe 82 are respectively communicated with the adjacent sections of the heating furnace 5, the smoke discharging pipe 81 and the smoke passing pipe 82 are respectively provided with a shock absorber 83 at the air inlet end, the shock absorber 83 is a corrugated pipe with a triangular bending end, and the corrugated pipe is made of spring steel. Set up combustion-supporting wind heat exchanger 8 and be used for inhaling the hot-air in the furnace chamber 51, simultaneously discharge through blast pipe 84 of combustion-supporting wind heat exchanger 8 opposite side for the work of heat recovery such as steam power generation reduces the wasting of resources, cooperates trachea 53 constantly to supply oxygen simultaneously, makes and keeps higher oxygen content in the furnace chamber 51, and then enables the combustible gas fully combustion in the nozzle 52, and the heat can fully release, improves energy utilization. In addition, the smoke through pipe 82 is arranged to be communicated with the multiple sections of heating furnaces 5, so that gas in each section of heating furnace 5 can flow, and the problem that the assembly cost is high because each section of heating furnace 5 is provided with a combustion-supporting air heat exchanger 8 is solved. In addition, set up the bumper shock absorber 83 and be used for cutting the pipeline vibration that causes when reducing the hot-air and flow, through the structural feature and the material characteristic of bumper shock absorber 83, when hot-air causes the impact to the pipeline, the bumper shock absorber 83 reduces gaseous impact through self elasticity, and the vibration of avoiding assaulting the production is shaken the pine with the connecting bolt, guarantees that exhaust pipe 81 and logical tobacco pipe 82 can the stable connection on heating furnace 5. In addition, the impact reduction can also play a certain silencing role, reduce the noise when gas flows through a pipeline, and avoid the rotary kiln from generating noise pollution to the surrounding environment.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. An external combustion type rotary kiln is characterized in that: the device comprises a feeding hopper (1), a screw feeder (2), a rotary drum (3), a driving part (4), a heating furnace (5), a discharging device (6), a roller sealer (7), a combustion-supporting air heat exchanger (8) and an extraction pipe (9), wherein the feeding hopper (1) is erected at the feeding end of the screw feeder (2) to enable materials in the feeding hopper (1) to move towards the screw feeder (2); the rotary drum (3) is a cylindrical drum, the length direction of the rotary drum (3) is horizontal or inclined, and one end of the rotary drum (3) is rotatably connected to the discharge end of the screw feeder (2) so that the materials enter the rotary drum (3); the driving part (4) is erected on one side of the rotary drum (3) to drive the rotary drum (3) to rotate; the heating furnace (5) is erected outside the rotary drum (3), and the temperature in the heating furnace (5) is between 700 and 1350 ℃; the other end of the rotary drum (3) is rotationally connected with a discharging device (6); two groups of roller sealers (7) are respectively fixedly connected on the screw feeder (2) and the discharging device (6), and the roller sealers (7) are tightly attached to the outer wall of the rotary drum (3); the combustion-supporting air heat exchanger (8) is erected at the top of the heating furnace (5) and is communicated with the heating furnace (5); the extraction pipe (9) is erected on one side of the discharging device (6) and is used for extracting carbon dioxide gas.

2. An external combustion rotary kiln as defined in claim 1, wherein: one section or multistage heating furnace (5) distribute along rotary drum (3) length direction, have linked firmly on rotary drum (3) between adjacent section heating furnace (5) and have supported rolling ring (31), support rolling ring (31) external diameter and be greater than rotary drum (3) external diameter, support rolling ring (31) bottom butt has the multiunit running roller, the running roller rotates to be connected on the wheel carrier, the wheel carrier is fixed subaerial.

3. An external combustion rotary kiln according to claim 2, wherein: the top part between the adjacent sections of heating furnaces (5) is provided with a smoke through pipe (82), and two ends of the smoke through pipe (82) are respectively communicated with the adjacent sections of heating furnaces (5).

4. An external combustion rotary kiln according to claim 3, wherein: the air inlet end of the combustion-supporting air heat exchanger (8) is fixedly connected with an exhaust pipe (81), the two ends of the exhaust pipe (81) are respectively communicated with the combustion-supporting air heat exchanger (8) and the heating furnace (5), the exhaust pipe (81) and the smoke through pipe (82) are respectively provided with a shock absorber (83) at the air inlet end, and the shock absorber (83) is a corrugated pipe with a triangular bent end.

5. An external combustion rotary kiln according to claim 2, wherein: the heating furnace (5) is made of heat-insulating materials, a furnace chamber (51) is arranged between the middle part of the heating furnace (5) and the rotary drum (3), and two ends of the heating furnace (5) are abutted against the outer wall surface of the rotary drum (3); a plurality of groups of burners (52) are arranged on one side of the bottom of the furnace chamber (51) of the heating furnace (5), combustible gas is introduced into the burners (52), and the outer ports of the burners (52) ignite the gas to generate heat to heat the rotary drum (3).

6. An external combustion rotary kiln according to claim 5, wherein: kiln body sealer (55) is fixedly connected between adjacent sections of heating furnace (5), kiln body sealer (55) is an annular structure made of heat-insulating material, the outer walls of two ports of kiln body sealer (55) are protruded, the cross sections of protruding ends are trapezoidal, the protruding ends of kiln body sealer (55) are embedded into heating furnace (5), and the inner end face of kiln body sealer (55) is abutted to the outer wall of rotary drum (3).

7. An external combustion rotary kiln according to claim 5, wherein: the multiple groups of burners (5) are distributed at intervals along the length direction of the rotary drum (3), the heights of the multiple groups of burners (5) are lower than the height of the rotary drum (3), a plurality of air pipes (53) are surrounded at intervals around the burners (5), and oxygen is introduced into the air pipes (53).

8. An external combustion rotary kiln as defined in claim 1, wherein: an air receiving opening (24) is formed in the top of the screw feeder (2), and an air pump is connected to the air receiving opening (24); a filter screen is arranged below the air collecting port (24); the bottom of the screw feeder (2) is provided with a slag discharge pipe (25), and the filter screen is positioned above the slag discharge pipe (25).

9. An external combustion rotary kiln as defined in claim 1, wherein: drive unit (4) are including driving motor (41), reduction gear (42), driving gear (43) and driven gear (44), driving motor (41) and reduction gear (42) all link firmly on ground or ground platform, driving motor (41) output links firmly with reduction gear (42) input, reduction gear (42) output links firmly with driving gear (43), driven gear (44) link firmly on rotary drum (3), driven gear (44) axis and rotary drum (3) axis coincidence, driving gear (43) and driven gear (44) meshing.

10. An external combustion rotary kiln as defined in claim 1, wherein: the roller sealer (7) is of an annular structure formed by a plurality of groups of arc-shaped flaky metal plates in a surrounding mode, the adjacent metal plates are tightly attached, the inner arc surfaces of the metal plates are abutted with the outer wall of the rotary drum (3) to be further bent, and therefore the roller sealer (7) is in surface contact with the rotary drum (3).