Active discharging device and discharging method of low-rank coal pyrolysis rotary kiln

Abstract

The invention relates to an active discharging device and discharging method for a low-rank coal pyrolysis rotary kiln, the active discharging device is arranged at the tail of the rotary kiln, and the active discharging device comprises a rotary lifting mechanism, a spiral discharging mechanism, an end plate and a discharging outer cylinder; the end plate is in sealed connection with the kiln tail barrel; the discharging outer barrel is arranged on the outer side of the end plate; the spiral discharging mechanism is composed of a driving spiral and a spiral mechanism shell. The rotary lifting mechanism comprises a plurality of lifting dustpans arranged between the spiral discharging mechanism and the kiln tail barrel; a solid phase discharge channel is formed between the screw mechanism shell and the driving screw, and a gas phase discharge channel is formed between the screw mechanism shell and the discharge outer cylinder. According to the invention, gas-solid two-phase products in the rotary kiln can be respectively led out through the corresponding channels, so that the flow rate of raw gas is reduced on the basis of ensuring smooth discharge of upgraded coal, and the dust content in the raw gas is further reduced; solid-phase products are discharged through the driving screw, the discharging capacity is high, the size of the sealing end face can be reduced, and the sealing effect is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of low-rank coal pyrolysis, and in particular to an active discharging device and a discharging method for a low-rank coal pyrolysis rotary kiln. Background Art

[0002] The pyrolysis products of low-rank coal consist of upgraded coal (solid phase) and raw coal gas (gas phase, containing dust, tar, and coal gas). When using a rotary kiln pyrolysis process, the heat source is typically input from the rear end of the rotary kiln (discharge end), and the coal to be pyrolyzed enters from the head end (feed end) of the rotary kiln. The two exchange heat in a countercurrent flow inside the rotary kiln. Because raw coal gas contains a large amount of dust and vaporized tar, to prevent tar precipitation and clogging subsequent chemical recovery pipelines, the raw coal gas should be discharged simultaneously with the upgraded coal from the higher-temperature rear end of the rotary kiln through the discharge device.

[0003] Low-rank coal pyrolysis rotary kilns typically use two types of discharge devices: an active discharge device coupled with a screw conveyor, and a passive discharge device with a spiral tube installed at the rear of the rotary kiln. Currently, passive discharge devices, which utilize a tapered barrel with a spiral tube, are often used. However, once the spiral tube diameter and pitch are determined, the discharge capacity is completely dependent on the rotation speed of the rotary kiln barrel itself. Furthermore, with passive discharge devices, both gas and solid phases are discharged through the same channel. Consequently, passive discharge devices present the following problems and drawbacks:

[0004] (1) The rotation speed of the rotary kiln is usually less than 3 rpm. When the passive spiral discharge method is used, the discharge capacity will be limited. Especially in the abnormal kiln stop state, the rotary kiln can only rely on the auxiliary transmission device to rotate slowly, and the material in the kiln cannot be discharged in time.

[0005] (2) In order to ensure basic discharge capacity, the diameter of the spiral tube should not be too small when using passive discharge mode, which requires increasing the diameter of the end sealing ring, resulting in increased sealing difficulty;

[0006] (3) The upgraded coal and raw gas are discharged from the same discharge port. After the diameter is reduced, the flow rate of the raw gas increases, which will carry away more dust and increase the difficulty of subsequent dust removal;

[0007] (4) The discharge device and the cylinder are an integrated structure, which is not conducive to the later maintenance of the components inside the kiln. Summary of the Invention

[0008] The present invention provides an active discharge device and method for a low-rank coal pyrolysis rotary kiln, which can respectively discharge the gas and solid phase products in the rotary kiln through corresponding channels. On the basis of ensuring the smooth discharge of the upgraded coal, the flow rate of the raw coal gas is reduced, thereby reducing the dust content in the raw coal gas; the solid phase products are discharged through the active spiral, with a strong discharge capacity, and are conducive to reducing the size of the sealing end face and improving the sealing effect.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] An active discharging device for a low-rank coal pyrolysis rotary kiln is arranged at the tail of the rotary kiln; it includes a rotary lifting mechanism, a spiral discharging mechanism, an end plate and a discharging outer cylinder; the end plate is sealed with the kiln tail cylinder, and the discharging outer cylinder is arranged on the outside of the end plate and communicates with the internal space of the rotary kiln; the spiral discharging mechanism is composed of a coaxially arranged active spiral and a spiral mechanism shell, and the spiral mechanism shell is fixed; the inner end of the spiral discharging mechanism extends to the rotary lifting mechanism; the rotary lifting mechanism includes a plurality of lifting hoppers arranged between the spiral discharging mechanism and the kiln tail cylinder, and the lifting hoppers rotate with the rotary kiln; an opening is opened at the top of the spiral mechanism shell located in the rotary lifting mechanism; a solid phase discharge channel is formed between the spiral mechanism shell and the active spiral, and a gas phase discharge channel is formed between the spiral mechanism shell and the discharging outer cylinder.

[0011] An internal insulation layer is provided on the inner side of the kiln tail cylinder; an inner insulation layer is provided on the inner side of the end plate and the discharge outer cylinder, wherein the edge of the inner insulation layer on the inner side of the end plate is connected with the internal insulation layer of the cylinder, and extends a distance toward the inner side of the kiln tail cylinder, and the extension section has a transition angle.

[0012] The end plate is detachably connected to the kiln tail cylinder via a flange, and a sealing member is provided at the flange connection.

[0013] A collecting hopper is provided at the hole on the top of the spiral mechanism shell. The collecting hopper is a cone structure with a large upper opening and a small lower opening. The bottom of the collecting hopper is connected to the spiral mechanism shell, and the top of the collecting hopper extends to both sides of the spiral discharge mechanism.

[0014] The rotary material lifting mechanism consists of a material lifting bucket, a material distribution ring and a connecting ring; the material distribution ring is coaxially arranged with the kiln tail cylinder, the inner end of the material lifting bucket is connected to the material distribution ring, and the outer end of the material lifting bucket is connected to the kiln tail cylinder; connecting rings are respectively provided on both sides of the material lifting bucket, and the inner ring of the connecting ring is connected to the material distribution ring; a notch is provided on the material distribution ring between two adjacent material lifting buckets as a material discharge port.

[0015] The material lifting bucket is a dustpan-shaped structure composed of a bottom plate and two side plates, and the discharge end of the material lifting bucket is connected to the material distribution ring.

[0016] A method for discharging low-rank coal from a rotary kiln for pyrolysis includes the following steps:

[0017] 1) Low-rank coal enters the kiln head of the rotary kiln, is pyrolyzed into upgraded coal, and reaches the kiln tail as the rotary kiln rotates. The upgraded coal at the kiln tail enters the lifting bucket, which is lifted to the top of the spiral discharge mechanism as the rotary kiln rotates. Under the action of its own weight, it slides through the gap in the distribution ring into the collection hopper below and is discharged by the active spiral.

[0018] 2) The heat source enters from the kiln tail of the rotary kiln and exchanges heat with the low-rank coal in a countercurrent manner, achieving pyrolysis of the low-rank coal and generating raw coal gas at the same time; the raw coal gas passes through the gaps between the lifting buckets and is discharged from the annular channel between the spiral mechanism shell and the discharge outer cylinder.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) The active discharge device of the present invention can improve the discharge capacity by adjusting the number of revolutions of the screw conveyor. The discharge speed does not depend on the number of revolutions of the rotary kiln, which is beneficial to improving the stability and controllability of production.

[0021] 2) In the active discharge device of the present invention, the diameter of the screw conveyor is much smaller than that of the passive spiral tube, and the end face sealing diameter is reduced, which is conducive to improving the sealing effect.

[0022] 3) By adopting the active discharge device of the present invention, the gas-solid two-phase products are discharged separately through their respective channels, which can reduce the raw coal gas flow rate while ensuring the smooth discharge of the upgraded coal, thereby reducing the dust content in the raw coal gas.

[0023] 4) By adopting the active discharge device of the present invention, both gas and solid phase products are discharged from the high temperature section, and the tar components in the raw gas are not easily precipitated, thereby improving the stability of the subsequent chemical production process.

[0024] 5) The active discharge device of the present invention is connected to the drum of the rotary kiln by a flange, which is easy to disassemble and more convenient for the installation and maintenance of the rotary kiln during the operation inside the kiln.

[0025] 6) The active discharge device of the present invention is not affected by the insulation form of the rotary kiln and is applicable to rotary kilns using internal insulation (refractory bricks, castables, etc. in the kiln) or external insulation (heated drum), and has stronger applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the three-dimensional structure of the active discharge device of the present invention.

[0027] Figure 2 yes Figure 1 A-direction view in.

[0028] In the figure: 1-kiln tail cylinder; 2-insulation layer inside the cylinder; 3-end plate; 4-inner insulation layer; 5-discharge outer cylinder; 6-lifting scoop; 7-connecting ring; 8-distributing ring; 9-collecting hopper; 10-driving screw; 11-screw mechanism shell. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0030] like Figure 1 、 Figure 2 As shown, the active discharging device of the low-rank coal pyrolysis rotary kiln described in the present invention is arranged at the tail of the rotary kiln; it includes a rotary lifting mechanism, a spiral discharging mechanism, an end plate 3 and a discharging outer cylinder 5; the end plate 3 is sealed with the kiln tail cylinder 1, and the discharging outer cylinder 5 is arranged on the outside of the end plate 3 and communicates with the internal space of the rotary kiln; the spiral discharging mechanism is composed of a coaxially arranged active spiral 10 and a spiral mechanism shell 11, and the spiral mechanism shell 11 is fixed; the inner end of the spiral discharging mechanism extends to the rotary lifting mechanism; the rotary lifting mechanism includes a plurality of lifting scoops 6 arranged between the spiral discharging mechanism and the kiln tail cylinder 1, and the lifting scoops 6 rotate with the rotary kiln; an opening is opened at the top of the spiral mechanism shell 11 located in the rotary lifting mechanism; a solid phase discharge channel is formed between the spiral mechanism shell 11 and the active spiral 10, and a gas phase discharge channel is formed between the spiral mechanism shell 11 and the discharging outer cylinder 5.

[0031] An internal thermal insulation layer 2 is provided on the inner side of the kiln tail cylinder 1; an internal thermal insulation layer 4 is provided on the inner sides of the end plate 3 and the discharge outer cylinder 5, wherein the edge of the internal thermal insulation layer 4 on the inner side of the end plate 3 is connected with the internal thermal insulation layer 2 of the cylinder, and extends a distance toward the inner side of the kiln tail cylinder 1, and the extension section has a transition angle.

[0032] The end plate 3 is detachably connected to the kiln tail cylinder 1 via a flange, and a seal is provided at the flange connection.

[0033] A collecting hopper 9 is provided at the hole at the top of the spiral mechanism housing 11. The collecting hopper 9 is a cone structure with a large upper opening and a small lower opening. The bottom of the collecting hopper 9 is connected to the spiral mechanism housing 11, and the top of the collecting hopper 9 extends to both sides of the spiral discharge mechanism.

[0034] The rotary material lifting mechanism consists of a material lifting scoop 6, a material distribution ring 8 and a connecting ring 7; the material distribution ring 8 is coaxially arranged with the kiln tail cylinder 1, the inner end of the material lifting scoop 6 is connected to the material distribution ring 8, and the outer end of the material lifting scoop 6 is connected to the kiln tail cylinder 1; connecting rings 7 are respectively provided on both sides of the material lifting scoop 6, and the inner ring of the connecting ring 7 is connected to the material distribution ring 8; a notch is provided on the material distribution ring 8 between two adjacent material lifting scoops 6 as a material discharge port.

[0035] The lifting bucket 6 is a dustpan-shaped structure composed of a bottom plate and two side plates, and the discharge end of the lifting bucket 6 is connected to the distribution ring 8.

[0036] The present invention provides a method for discharging low-rank coal from a rotary kiln, comprising the following steps:

[0037] 1) Low-rank coal enters the rotary kiln head, undergoes pyrolysis, and is converted into upgraded coal. The upgraded coal reaches the kiln tail as the rotary kiln rotates. The upgraded coal at the kiln tail enters the lifting hopper 6, which is lifted to the top of the spiral discharge mechanism as the rotary kiln rotates. Under its own weight, the coal slides through the notch in the distribution ring 8 into the collection hopper 9 below and is discharged by the active spiral 10.

[0038] 2) The heat source enters from the kiln tail of the rotary kiln and exchanges heat with the low-rank coal in countercurrent flow, achieving pyrolysis of the low-rank coal and generating raw coal gas at the same time; the raw coal gas passes through the gaps between the lifting buckets 6 and is discharged from the annular channel between the spiral mechanism shell 11 and the discharge outer cylinder 5.

[0039] The present invention describes an active discharging device for a low-rank coal pyrolysis rotary kiln. The feeding end of the spiral discharging mechanism extends to the tail of the rotary kiln. The material to be discharged (improved coal) enters the lifting bucket 6 and is lifted as the cylinder at the tail of the kiln rotates. After reaching the top of the spiral discharging mechanism, it slides into the collecting hopper 9 below through the notch provided on the distribution ring 8 under the action of its own weight, and is discharged from the rotary kiln through the active spiral 10 along the solid phase discharge channel between the active spiral 10 and the spiral mechanism casing 11.

[0040] Several lifting scoops 6 are evenly distributed along the circumference of the rotary kiln. They are welded together with a distribution ring 8 via connecting rings 7 on either side. The distribution ring 8 is coaxial with the rotary kiln, and a gap is provided between each lifting scoop 6 as a discharge port. The other end of the lifting scoop 6 is welded to the kiln tail cylinder 1 of the rotary kiln.

[0041] The rotary kiln cylinder is usually provided with an insulation layer. In the present invention, an inner insulation layer 4 can be provided inside the end plate 3 and the discharge outer cylinder 5 as needed, and the inner insulation layer 4 is connected with the inner insulation layer 2 of the kiln tail cylinder 1.

[0042] There is a certain distance between the distribution ring 8 and the end plate 3, through which the raw gas produced by the pyrolysis of low-rank coal enters the annular area between the discharge outer cylinder 5 and the spiral mechanism shell 11, and is then discharged out of the rotary kiln.

[0043] The end plate 3 is connected to the kiln tail cylinder 1 by a flange. During the overall installation and maintenance of the rotary kiln, the discharge device can be disassembled as a whole to facilitate the operation and construction inside the kiln.

[0044] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An active discharge device for a low-rank coal pyrolysis rotary kiln, located at the tail of the rotary kiln; characterized in that: It includes a rotary lifting mechanism, a spiral discharging mechanism, an end plate and a discharge outer cylinder; the end plate is sealed with the kiln tail cylinder, and the discharge outer cylinder is arranged on the outside of the end plate and communicates with the internal space of the rotary kiln; the spiral discharging mechanism is composed of a coaxially arranged active spiral and a spiral mechanism shell, and the spiral mechanism shell is fixed; the inner end of the spiral discharging mechanism extends to the rotary lifting mechanism; the rotary lifting mechanism includes a plurality of lifting scoops arranged between the spiral discharging mechanism and the kiln tail cylinder, and the lifting scoops rotate with the rotary kiln; an opening is opened on the top of the spiral mechanism shell located in the rotary lifting mechanism; a solid phase discharge channel is formed between the spiral mechanism shell and the active spiral, and a gas phase discharge channel is formed between the spiral mechanism shell and the discharge outer cylinder.

2. The active discharge device of the low-rank coal pyrolysis rotary kiln according to claim 1, characterized in that: An internal insulation layer is provided on the inner side of the kiln tail cylinder; an inner insulation layer is provided on the inner side of the end plate and the discharge outer cylinder, wherein the edge of the inner insulation layer on the inner side of the end plate is connected with the internal insulation layer of the cylinder, and extends a distance toward the inner side of the kiln tail cylinder, and the extension section has a transition angle.

3. The active discharge device of the low-rank coal pyrolysis rotary kiln according to claim 1 or 2, characterized in that: The end plate is detachably connected to the kiln tail cylinder via a flange, and a sealing member is provided at the flange connection.

4. The active discharge device of the low-rank coal pyrolysis rotary kiln according to claim 1, characterized in that: A collecting hopper is provided at the hole on the top of the spiral mechanism shell. The collecting hopper is a cone structure with a large upper opening and a small lower opening. The bottom of the collecting hopper is connected to the spiral mechanism shell, and the top of the collecting hopper extends to both sides of the spiral discharge mechanism.

5. The active discharge device of the low-rank coal pyrolysis rotary kiln according to claim 1, characterized in that: The rotary material lifting mechanism consists of a material lifting bucket, a material distribution ring and a connecting ring; the material distribution ring is coaxially arranged with the kiln tail cylinder, the inner end of the material lifting bucket is connected to the material distribution ring, and the outer end of the material lifting bucket is connected to the kiln tail cylinder; connecting rings are respectively provided on both sides of the material lifting bucket, and the inner ring of the connecting ring is connected to the material distribution ring; a notch is provided on the material distribution ring between two adjacent material lifting buckets as a material discharge port.

6. The active discharge device of the low-rank coal pyrolysis rotary kiln according to claim 1 or 5, characterized in that: The material lifting bucket is a dustpan-shaped structure composed of a bottom plate and two side plates, and the discharge end of the material lifting bucket is connected to the material distribution ring.

7. A method for discharging low-rank coal from a rotary kiln for pyrolysis, which is based on the active discharging device of the low-rank coal pyrolysis rotary kiln according to claim 1, 2, 4 or 5; characterized in that: The process includes the following: 1) Low-rank coal enters the kiln head of the rotary kiln, is pyrolyzed into upgraded coal, and reaches the kiln tail as the rotary kiln rotates. The upgraded coal at the kiln tail enters the lifting bucket, which is lifted to the top of the spiral discharge mechanism as the rotary kiln rotates. Under the action of its own weight, it slides through the gap in the distribution ring into the collection hopper below and is discharged by the active spiral. 2) The heat source enters from the kiln tail of the rotary kiln and exchanges heat with the low-rank coal in a countercurrent manner, achieving pyrolysis of the low-rank coal and generating raw coal gas at the same time; the raw coal gas passes through the gaps between the lifting buckets and is discharged from the annular channel between the spiral mechanism shell and the discharge outer cylinder.

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