A porous inner sleeve radiant tube heated rotary kiln

Abstract

The present invention discloses a porous inner sleeve radiant tube heating rotary kiln, which comprises a kiln body. A material outlet is arranged at the front end of the inner cavity of the kiln body, and a material inlet is arranged at the rear end of the inner cavity of the kiln body. An air outlet collecting pipe is arranged at the material inlet. A material lifting plate, a middle gas collecting pipe and a porous inner sleeve are sequentially arranged in the inner cavity of the kiln body along the material conveying direction. The material lifting plate and the side wall of the kiln body form a material lifting plate interlayer. A kiln head burner is arranged at the material outlet, and the kiln head burner extends into the front end of the porous inner sleeve. A plurality of through holes are uniformly distributed on the barrel wall of the porous inner sleeve. The front end of the material lifting plate interlayer is communicated with the rear end of the middle gas collecting pipe through a gas guide pipe, and the rear end of the material lifting plate interlayer is communicated with the front end of the air outlet collecting pipe through a gas guide pipe. The present invention solves the problems of low hot air heat exchange efficiency and "ring formation" of low-melting-point materials caused by local high temperature at the combustion flame in the current rotary kiln.

Description

Technical Field

[0001] The present invention relates to a rotary kiln capable of heating coarse particles such as massive and powdery materials through radiant tubes. Background Art

[0002] A rotary kiln is a device widely used for heating and roasting materials. Existing rotary kilns generally heat and roast materials by end flames. The rotary kiln cylinder is supported by tyre and supporting rollers and is driven by a driving device to rotate the entire cylinder. The materials are tossed up in the rotary kiln cylinder and directly contact with high-temperature flames and hot air currents to achieve the heating and roasting of massive and powdery materials.

[0003] Currently, rotary kilns are applied to the heating and roasting of various minerals. According to different requirements for the roasting temperature of materials, the materials are directly heated by flames. However, the flames will generate local high temperatures, and some materials with low melting points in the materials will melt, making it difficult to solve the problem of "ring formation" in the rotary kiln. At the same time, the heat transfer efficiency between the high-temperature flames and hot air currents and the materials in the cavity of the kiln body is low. After the hot air current exits the kiln, secondary heat exchange is required, and sufficient heat transfer efficiency cannot be achieved in the rotary kiln. Therefore, the hot air heat transfer efficiency of the rotary kiln is low, and the local high temperature at the combustion flame causes the problem of "ring formation" of low-melting-point materials, restricting the wide use of rotary kilns. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide a rotary kiln with a porous inner sleeve radiant tube heating system, which solves the problems of low hot air heat transfer efficiency and "ring formation" of low-melting-point materials caused by local high temperature at the combustion flame in the current rotary kiln.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A rotary kiln with a porous inner sleeve radiant tube heating system includes a kiln body. A material outlet is provided at the front end of the inner cavity of the kiln body, and a material inlet is provided at the rear end of the inner cavity of the kiln body. An air outlet collecting pipe is provided at the material inlet. A material lifting plate, a middle gas collecting pipe, and a porous inner sleeve are sequentially arranged in the inner cavity of the kiln body along the material conveying direction. The material lifting plate and the side wall of the kiln body form a material lifting plate sandwich layer. A kiln head burner is provided at the material outlet, and the kiln head burner extends into the front end of the porous inner sleeve. A plurality of through holes are evenly distributed on the barrel wall of the porous inner sleeve. The front end of the material lifting plate sandwich layer is communicated with the rear end of the middle gas collecting pipe through a guide pipe, and the rear end of the material lifting plate sandwich layer is communicated with the front end of the air outlet collecting pipe through a guide pipe.

[0007] Furthermore, the length of the porous inner sleeve is adjustable, so that a convective heat transfer area is formed between the front end of the porous inner sleeve and the rear end of the middle gas collecting pipe, or the front end of the porous inner sleeve is docked with the rear end of the middle gas collecting pipe.

[0008] Further, a detachable end plug is provided at the rear end of the porous inner sleeve, and a detachable orifice plug is provided at the through hole of the cylinder wall.

[0009] Further, a plurality of groups of material lifting plates are provided, and each group of material lifting plates and the side wall of the kiln body form a material lifting plate interlayer. The air guide pipes are arranged in a radial pattern, and the number of air guide pipes is equal to and corresponds one by one to the number of material lifting plate interlayers.

[0010] Further, the material lifting plates are made of corrugated steel plates.

[0011] Further, the middle gas collecting pipe and the porous inner sleeve are both supported and fixed by the inner sleeve.

[0012] Further, a feed chute and a kiln tail hood are provided outside the material inlet.

[0013] Further, the exhaust gas collecting pipe is supported and fixed by the kiln tail hood.

[0014] Further, a kiln head hood is provided outside the material outlet.

[0015] Further, the kiln head burner is supported and fixed by the kiln head hood.

[0016] Beneficial effects:

[0017] 1) Realize the roasting and heating of the inner sleeve radiation pipe. The heating area and effective roasting time in the kiln are extended, and a uniform and controllable temperature field is formed in the length direction of the kiln body.

[0018] 2) The porous structure of the inner sleeve can effectively discharge the combustion residues, and at the same time, three heat exchange forms of heat conduction, heat convection and heat radiation are formed in the kiln, improving the heat exchange efficiency.

[0019] 3) Avoid the direct burning of materials by high-temperature concentrated flames, reducing the possibility of "ring formation" due to the melting of low-melting material components in the kiln.

[0020] 4) Greatly reduce air leakage and reduce the heat loss carried away by the hot air out of the kiln. Avoid the formation of excessive nitrogen compounds when a large amount of air enters the kiln for combustion. Brief description of the drawings

[0021] Figure 1 It is a schematic structural diagram of the porous inner sleeve radiation pipe heating rotary kiln of the present invention.

[0022] Figure 2 It is Figure 1 the schematic cross-sectional view of A-A in

[0023] Figure 3 It is Figure 1 the schematic cross-sectional view of B-B in

[0024] Figure 4 It is a docking state diagram of the porous inner sleeve and the middle gas collecting pipe.

[0025] Figure 5 It is a structural schematic diagram of the porous inner sleeve.

[0026] In the figure: 1-kiln head burner, 2-kiln head hood, 3-porous inner sleeve, 4-kiln body, 5-middle gas collecting pipe, 6-feeding plate sandwich, 7-feeding chute, 8-kiln tail hood, 9-outlet gas collecting pipe, 10-inner sleeve support, 11-guide pipe, 12-convective heat exchange area, 13-feeding plate, 14-through hole, 15-end plug, 16-orifice plug. Specific implementation mode

[0027] The following further explains the present invention in conjunction with the attached drawings.

[0028] As Figure 1 shown, a rotary kiln heated by a porous inner sleeve radiation tube of the present invention includes a kiln body 4. A material outlet is provided at the front end of the inner cavity of the kiln body 4, and a material inlet is provided at the rear end of the inner cavity of the kiln body 4. An outlet gas collecting pipe 9 is provided at the material inlet. A feeding plate 13, a middle gas collecting pipe 5, and a porous inner sleeve 3 are sequentially arranged in the inner cavity of the kiln along the material conveying direction. The feeding plate 13 and the side wall of the kiln body 4 form a feeding plate sandwich 6. A kiln head burner 1 is provided at the material outlet, and the kiln head burner 1 extends into the front end of the porous inner sleeve 3. A plurality of through holes 14 are evenly distributed on the barrel wall of the porous inner sleeve 3. The front end of the feeding plate sandwich 6 is communicated with the rear end of the middle gas collecting pipe 5 through a guide pipe 11, and the rear end of the feeding plate sandwich 6 is communicated with the front end of the outlet gas collecting pipe 9 through a guide pipe 11.

[0029] As Figure 1 and 4 shown, the length of the porous inner sleeve 3 is adjustable, so that a convective heat exchange area 12 is formed between the front end of the porous inner sleeve 3 and the rear end of the middle gas collecting pipe 5, or the front end of the porous inner sleeve 3 is docked with the rear end of the middle gas collecting pipe 5.

[0030] As Figure 5 shown, a detachable end plug 15 is provided at the rear end of the porous inner sleeve 3. The end plug 15 is threadedly connected to the rear end of the porous inner sleeve 3. A detachable orifice plug 16 is provided on the through hole 14 of the barrel wall. The orifice plug 16 is threadedly connected to the through hole 14.

[0031] As Figure 2 shown, several groups of feeding plates 13 are provided. Each group of feeding plates 13 and the side wall of the kiln body 4 form a feeding plate sandwich 6. The guide pipes 11 are arranged radially. The number of the guide pipes 11 is equal to and corresponds to the number of the feeding plate sandwiches 6 one by one. The feeding plate 13 is made of corrugated steel plate.

[0032] As Figure 3As shown, the middle gas collecting pipe 5 and the porous inner sleeve 3 are both fixed by the inner sleeve support 10. The middle gas collecting pipe 5 and the porous inner sleeve 3 are coaxially arranged at the central position of the inner cavity of the kiln body 4. A number of inner sleeve supports 10 are evenly distributed in the annular area between the outer sides of the middle gas collecting pipe 5 and the porous inner sleeve 3 and the side wall of the kiln body 4. The two ends of the inner sleeve support 10 are respectively fixedly connected to the middle gas collecting pipe 5, the porous inner sleeve 3 and the side wall of the kiln body 4.

[0033] As Figure 1 shown, a feeding chute 7 and a kiln tail hood 8 are provided outside the material inlet. The material to be heated is put into the material inlet through the feeding chute 7. The outlet gas collecting pipe 9 is supported and fixed by the kiln tail hood 8. The tail end of the outlet gas collecting pipe 9 passes through the kiln tail hood 8 and is fixedly connected thereto. A kiln head hood 2 is provided outside the material outlet. The kiln head burner 1 is supported and fixed by the kiln head hood 2. The kiln head burner 1 passes through the kiln head hood 2 and is fixedly connected thereto.

[0034] As Figure 1 shown, in the state where a convection heat exchange area 12 is formed between the front end of the porous inner sleeve 3 and the rear end of the middle gas collecting pipe 5, the rear end of the porous inner sleeve 3 is closed by the end plug 15, and the orifice plug 16 is disassembled. When the rotary kiln works, fuel is fed into the kiln head burner 1 and burns in the porous inner sleeve 3 to generate a flame and high-temperature flue gas, which heats the material in the rotary kiln cavity by thermal radiation. The through holes 14 blow the combustion flue gas into the kiln body 4 for heat exchange with the material. At the same time, the residues generated by the flame combustion can be discharged from the porous inner sleeve 3 through the through holes 14 distributed on the porous inner sleeve 3, making it suitable for the combustion of powder fuel and avoiding the accumulation of residues in the porous inner sleeve after combustion. By setting the porous inner sleeve 3, the heating and roasting area is extended, avoiding direct burning of the material by the flame to cause local high heat of the material and preventing the formation of molten material to cause the "ring formation" in the rotary kiln.

[0035] The high-temperature flue gas blown out of the through holes 14 of the porous inner sleeve 3 into the cavity of the kiln body exchanges heat with the material in the convection heat exchange area 12, and then is inhaled by the middle gas collecting pipe 5 and enters the lifting plate sandwich 6 through the guide pipe 11 to exchange heat with the material just entering the kiln again, drying the material just entering the kiln. The lifting plate 13 is a corrugated steel plate, and the material is scattered on the surface of the lifting plate 13, increasing the heat exchange area and improving the heat exchange efficiency during the process of lifting and spreading the material. Finally, the tail gas is discharged through the outlet gas collecting pipe 9. In this way, the flue gas after combustion exchanges heat with the material through three areas of the kiln body 4, namely, the thermal radiation area of the porous inner sleeve 3, the convection heat exchange area 12 and the lifting heat conduction area of the lifting plate sandwich 6. The heating and heat exchange area is extended, and the heating and heat exchange time is also extended. The material is fully heated and heat exchanged, and three heat exchange methods of heat conduction, heat convection and thermal radiation are formed in the kiln, and the thermal efficiency will be significantly improved.

[0036] The central gas collecting pipe 5 extracts gas centrally in the middle of the kiln body 4. The extracted gas is mainly composed of combustion flue gas and gas generated during the drying and heating process of the material itself, significantly reducing the amount of air leaking into the two ends of the kiln body 4, greatly reducing the exhaust gas volume of the rotary kiln, and also reducing the generation amount of nitrogen oxides.

[0037] According to the flame characteristics of the burner and the material characteristics, the temperature field distributed in the rotary kiln cavity can be pre-simulated, the length of the inner sleeve can be set, and the positions, sizes and quantities of the through holes on the inner sleeve can be arranged to meet the heating requirements of different materials.

[0038] Such as Figure 4 As shown, if it is necessary to isolate the combustion flue gas from the gas generated during the drying and heating process of the material, adjust the length of the porous inner sleeve 3, dock the front end of the porous inner sleeve 3 with the rear end of the central gas collecting pipe 5, remove the end plug 15 at the rear end of the porous inner sleeve 3, and block the through hole 14 through the orifice plug 16, so that the gas generated during the drying and heating process of the material can be extracted.

[0039] When the porous inner sleeve 3 is docked with the central gas collecting pipe 5 and the through hole 14 is blocked, when the rotary kiln is working, fuel is fed into the burner at the kiln head 1 and burns in the porous inner sleeve 3 to generate a flame and high-temperature flue gas. The high-temperature flue gas exchanges heat with the material outside the porous inner sleeve 3 when passing through the inner sleeve 3, and then enters the lifting plate sandwich 6 through the gas guide pipe 11, exchanges heat with the material just entering the kiln again, dries the material just entering the kiln, and finally is discharged through the gas outlet collecting pipe 9. The material is dried and heated when passing through the inner sleeve 3, and the gas generated during the drying and heating process is discharged through the exhaust port at the upper end of the kiln head hood 2 and collected. During this process, the combustion flue gas and the gas generated during the drying and heating process of the material are completely isolated.

[0040] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A porous inner sleeve radiant tube heated rotary kiln, comprising a kiln body, a material outlet is provided at the front end of the inner cavity of the kiln body, and a material inlet is provided at the rear end of the inner cavity of the kiln body, and it is characterized in that: The material inlet is provided with an exhaust gas collecting pipe. In the inner cavity of the kiln body, a material lifting plate, a middle gas collecting pipe, and a porous inner sleeve are sequentially arranged along the material conveying direction. The material lifting plate and the side wall of the kiln body form a material lifting plate interlayer. The material outlet is provided with a burner at the kiln head, and the burner at the kiln head extends into the front end of the porous inner sleeve. A plurality of through holes are evenly distributed on the barrel wall of the porous inner sleeve. The front end of the material lifting plate interlayer is communicated with the rear end of the middle gas collecting pipe through a gas guide pipe, and the rear end of the material lifting plate interlayer is communicated with the front end of the exhaust gas collecting pipe through a gas guide pipe.

2. The porous inner sleeve radiant tube heated rotary kiln according to claim 1, characterized in that: The length of the porous inner sleeve is adjustable, so that a convective heat exchange area is formed between the rear end of the porous inner sleeve and the front end of the middle gas collecting pipe, or the rear end of the porous inner sleeve is docked with the front end of the middle gas collecting pipe.

3. A porous inner sleeve radiant tube heated rotary kiln according to claim 2, characterized in that: A detachable end plug is provided at the rear end of the porous inner sleeve, and a detachable orifice plug is provided at the through hole on the barrel wall.

4. A porous inner sleeve radiant tube heated rotary kiln according to claim 1, characterized in that: A plurality of groups of the material lifting plates are provided. Each group of material lifting plates and the side wall of the kiln body form a material lifting plate interlayer. The gas guide pipes are arranged in a radial pattern, and the number of gas guide pipes is equal to and corresponds to the number of material lifting plate interlayers one by one.

5. A porous inner sleeve radiant tube heated rotary kiln according to claim 4, characterized in that: The material lifting plate is made of corrugated steel plate.

6. A porous inner sleeve radiant tube heated rotary kiln according to claim 1, characterized in that: The middle gas collecting pipe and the porous inner sleeve are both supported and fixed by an inner sleeve.

7. A porous inner sleeve radiant tube heated rotary kiln according to claim 1, characterized in that: A feed chute and a kiln tail hood are provided outside the material inlet.

8. A porous inner sleeve radiant tube heated rotary kiln according to claim 7, characterized in that: The exhaust gas collecting pipe is supported and fixed by the kiln tail hood.

9. A porous inner sleeve radiant tube heated rotary kiln according to claim 1, characterized in that: A kiln head hood is provided outside the material outlet.

10. A porous inner sleeve radiant tube heated rotary kiln according to claim 9, characterized in that: The burner at the kiln head is supported and fixed by the kiln head hood.

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