Rotary pyrolysis device with internal and external heat integration and internal material returning mechanism

Abstract

The present application belongs to the technical field of pyrolysis device, and particularly relates to an inner-outer heat integrated rotary pyrolysis device with an internal returning mechanism. The present application comprises a supporting device, a cracking inner cylinder, a transmission device, a kiln tail cover, a spiral feeding device for conveying materials and an external flue for passing in flue gas. The cracking inner cylinder is rotationally connected to the supporting device, the output end of the transmission device is connected to the cracking inner cylinder, the external flue is sleeved on the cracking inner cylinder, the outlet end of the spiral feeding device is rotationally connected to one end of the cracking inner cylinder, and the other end of the cracking inner cylinder is rotationally connected to the kiln tail cover. The cracking inner cylinder is arranged obliquely, a section of the cracking inner cylinder extending into the kiln tail cover is provided with a drum screen, the cracking inner cylinder is filled with a heat carrier, and a returning spiral for returning the heat carrier is arranged on the inner wall of the cracking inner cylinder. The present application provides an inner-outer heat integrated rotary pyrolysis device which utilizes internal circulation heat carrier to strengthen the heat and mass transfer process and assist in removing the coke in the furnace.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pyrolysis devices, and particularly relates to an internal-external heat integrated rotary pyrolysis device with an internal return material mechanism. BACKGROUND

[0002] Organic solid waste low-temperature anaerobic pyrolysis is a process in which organic macromolecular components in organic solid waste are broken down to produce small molecule gas, tar and residue in an oxygen-free or hypoxic environment. The organic solid waste low-temperature anaerobic pyrolysis technology not only can realize the harmless, reduction and resource of organic solid waste, obtain pyrolysis oil gas, pyrolysis carbon and other multi-product, but also can effectively overcome the problem of dioxin generated by incineration, and is an effective treatment method. At present, the common external heat rotary pyrolysis device adopts high-temperature flue gas generated by combustion of gas or pyrolysis oil gas to transfer heat to the materials in the pyrolysis furnace through the metal wall surface. This kind of heat transfer method has the problems of poor heat transfer performance, uneven heating of materials in the furnace, uncontrollable pyrolysis products and the like. In addition, coking is easy to occur in the process of organic solid waste pyrolysis, and the coking products will adhere to the inner wall of the pyrolysis furnace and are difficult to clean, which increases the heat transfer resistance on one side of the inner wall of the pyrolysis furnace, reduces the heat transfer capacity, and decreases the economic efficiency of the equipment operation. In severe cases, it may even cause equipment damage and accidents.

[0003] The problems of poor process heat conduction and easy coking in the pyrolysis process have become important problems restricting the long-period economic, stable and safe operation of the pyrolysis furnace, and need to be improved. SUMMARY

[0004] In order to solve the above problems existing in the prior art, the purpose of the present application is to provide an internal-external heat integrated rotary pyrolysis device which utilizes internal circulation heat carrier to strengthen the heat and mass transfer process and assist in removing coking in the furnace.

[0005] The technical scheme adopted by the present application is as follows:

[0006] The rotary pyrolysis device with internal and external heat integration and internal return mechanism comprises a supporting device, a cracking inner cylinder, a transmission device, a kiln tail cover, a spiral feeding device for conveying materials and an external flue for passing in flue gas, the cracking inner cylinder is rotationally connected to the supporting device, the output end of the transmission device is connected to the cracking inner cylinder, the external flue is sleeved on the cracking inner cylinder, the outlet end of the spiral feeding device is rotationally connected to one end of the cracking inner cylinder, and the other end of the cracking inner cylinder is rotationally connected to the kiln tail cover; the cracking inner cylinder is arranged obliquely, a section of the cracking inner cylinder extending into the kiln tail cover is provided with a drum screen, the cracking inner cylinder is filled with a heat carrier, and a return spiral for returning the heat carrier is arranged on the inner wall of the cracking inner cylinder; during the rotation of the cracking inner cylinder (201) for conveying materials from the head to the tail, the rotation direction of the return spiral (205) enables the heat carrier to be reversely conveyed from the tail to the head of the cracking inner cylinder (201); the starting point of the return spiral (205) is free of gap with the tail of the cracking inner cylinder (201), and the end point of the return spiral (205) is provided with a gap with the head of the cracking inner cylinder (201).

[0007] The rotary pyrolysis device adopts the material heating mode of internal and external heat integration, combines the heat transfer through the partition of high-temperature flue gas and the direct contact heat transfer of the high-temperature circulating heat carrier, optimizes the heat transfer mode, improves the uniformity of the heating of the materials in the furnace and the pyrolysis rate, and reduces the generation of tar and other non-condensable products in the pyrolysis products, and the heat carrier can also play a role in removing the coking on the inner wall of the cracking inner cylinder under the throwing action of the lifting plate.

[0008] The rotary pyrolysis device integrates the return spiral and the drum screen in the interior, so that the rotary pyrolysis device bears the functions of screening, returning and reheating of the heat carrier, thereby cancelling the complex external screening, conveying, lifting, reheating and other equipment required by the traditional internal heat type pyrolysis device, and having the advantages of short process flow, small equipment investment and low system energy consumption.

[0009] As a preferred scheme of the present application, the inclination angle of the cracking inner cylinder is 1°-5°. The cracking inner cylinder can be made of high-temperature-resistant and corrosion-resistant stainless steel materials such as 309S or 310S.

[0010] As a preferred scheme of the present application, the inner wall position of the furnace head of the cracking inner cylinder is provided with a spiral material guide plate. The spiral material guide plate is a short spiral plate group welded in the ring direction at the inner wall position of the furnace head of the cracking inner cylinder, and the rotation direction is determined according to the rotation of the cracking inner cylinder.

[0011] As a preferred scheme of the present application, a plurality of lifting plate groups are arranged on the inner wall of the cracking inner cylinder in the axial direction, and each lifting plate group comprises a plurality of lifting plates uniformly distributed in the circumferential direction of the inner wall of the cracking inner cylinder.

[0012] As a preferred scheme of the present application, the drum screen is of a curved surface structure, and the screen holes of the drum screen are in the form of slits.

[0013] As a preferred scheme of the present application, the outer wall of the cracking inner cylinder is provided with flue gas guide plates, the flue gas guide plates are located in the outer flue, the flue gas guide plates are in the form of spiral winding installation, and the helix angle of the flue gas guide plates is 30°-60°.

[0014] As a preferred scheme of the present application, the tail of the drum screen is provided with a material blocking ring for blocking the heat carrier, and the material blocking ring is provided with an opening for discharging pyrolysis oil gas.

[0015] As a preferred scheme of the present application, the cross section of the return screw is rectangular, triangular or trapezoidal, and the helix angle of the return screw is 30°-60°.

[0016] As a preferred scheme of the present application, the connection positions of the spiral feeding device and the cracking inner cylinder and the connection positions of the cracking inner cylinder and the kiln tail cover are provided with oil gas sealing devices, and the two connection positions of the outer wall flue and the cracking inner cylinder are provided with flue gas sealing devices.

[0017] As a preferred scheme of the present application, the back of the drum screen is provided with a vibration knocking device for removing the pyrolysis carbon blocking the screen hole.

[0018] The present application has the following beneficial effects:

[0019] 1. The rotary pyrolysis device of the present application adopts an internal and external heat integrated material heating mode, combines the heat transfer through the high-temperature flue gas interwall and the direct contact heat transfer of the high-temperature circulating heat carrier, optimizes the heat transfer mode, improves the heating uniformity of the materials in the furnace and the pyrolysis rate, and reduces the generation of tar and other non-condensable products in the pyrolysis products, and the heat carrier can also play a role in removing the coke on the inner wall of the cracking inner cylinder under the throwing action of the lifting plate.

[0020] 2. The rotary pyrolysis device of the present application integrates the return screw and the drum screen inside, so that the rotary pyrolysis device undertakes the functions of screening, returning and reheating of the heat carrier, thereby canceling the complex external screening, transportation, lifting and reheating equipment required by the traditional internal heat type pyrolysis device, and having the advantages of short process flow, small equipment investment and low system energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0021] Fig. 1 is a structural schematic diagram of the present application;

[0022] Fig. 2 is a sectional view of part of the structure of the present application;

[0023] Fig. 3 is a structural schematic diagram of the return screw;

[0024] Fig. 4 is a structural schematic diagram of the material blocking ring.

[0025] In the figure: 1-screw feeding device; 201-cracking inner cylinder; 202-screw guide plate; 203-lifting plate; 204-flue gas guide plate; 205-return spiral; 206-drum screen; 207-material retaining ring; 3-external flue; 4-kiln tail cover; 5-transmission device; 6-support device; 7-oil and gas sealing device; 8-flue gas sealing device. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features therein may be combined with each other unless there is a conflict.

[0028] like Figs. 1-4 As shown, the internal and external heat integrated rotary pyrolysis device with an internal return mechanism of this embodiment includes a supporting device, a cracking inner cylinder 201, a transmission device 5, a kiln tail hood 4, a spiral feeding device 1 for conveying materials and an external flue 3 for introducing flue gas. The cracking inner cylinder 201 is rotatably connected to the supporting device, the output end of the transmission device 5 is connected to the cracking inner cylinder 201, the external flue 3 is sleeved on the cracking inner cylinder 201, the outlet end of the spiral feeding device 1 is rotatably connected to one end of the cracking inner cylinder 201, and the other end of the cracking inner cylinder 201 is rotatably connected to the kiln tail hood 4; the cracking inner cylinder 201 is arranged at an angle, and a section of the cracking inner cylinder 201 extending into the kiln tail hood 4 is provided with a drum screen 206, the cracking inner cylinder 201 is filled with a heat carrier, and a return spiral 205 for returning the heat carrier is provided on the inner wall of the cracking inner cylinder 201.

[0029] Among them, the heat carrier used in the rotary pyrolysis device is a spherical particle with a particle size of 10 to 30 mm, which can be made of high-temperature resistant alumina, quartz or stainless steel.

[0030] The screw feeding device 1 adopts a tubular screw conveyor. The tail end of the screw feeding device 1 is connected to the cracking inner cylinder 201 through an oil and gas sealing device 7 and extends into the inner cylinder for a certain distance.

[0031] The cracking inner cylinder 201 is arranged obliquely, with an oblique angle of 1°-5°, and can be made of stainless steel material such as 309S or 310S which is resistant to high temperature and corrosion. The inner wall is also provided with a spiral guide plate 202 and a material throwing plate 203, which respectively play the roles of pushing the material forward, preventing the material from flowing backward, throwing the material and strengthening the mixing.

[0032] The spiral guide plate 202 is a short spiral plate group which is circumferentially welded on the inner wall of the furnace head of the cracking inner cylinder 201, and the rotation direction is determined according to the rotation of the cracking inner cylinder 201 to push the material forward.

[0033] The material throwing plate 203 is a metal plate with an angle which is formed by welding two flat plates with an included angle of 120°-150°. A group of the material throwing plates 203 is uniformly arranged along the inner wall of the cracking inner cylinder 201, and multiple groups of the material throwing plates 203 are uniformly arranged along the axial direction of the cracking inner cylinder 201, and adjacent two groups of the material throwing plates 203 are arranged staggeredly.

[0034] The flue gas guide plate 204 is arranged on the outer wall of the cracking inner cylinder 201 in a spiral winding manner, with a spiral angle of 30°-60°, and plays the roles of forcing the flue gas to flow, increasing the flue gas flow rate and strengthening the heat and mass transfer. In addition, the top of the flue gas guide plate 204 and the inner wall of the outer flue 3 have a gap of about 15-50 mm in height to adapt to the equipment processing and installation errors and thermal expansion and contraction.

[0035] The return material spiral 205 is a hollow channel with a rectangular cross section (which can also be designed as a triangular or trapezoidal cross section), which is arranged in a spiral winding manner along the inner wall of the cracking inner cylinder 201, with a spiral angle of 30°-60°, and the rotation direction should ensure that the material in the return material spiral 205 can be reversely transported from the tail of the furnace body to the head of the furnace body during the synchronous rotation of the cracking inner cylinder 201. The starting point of the return material spiral 205 has no gap with the tail of the cracking inner cylinder 201, and when the mixture of the heat carrier and the material is transported from the central part of the cracking inner cylinder 201 to the tail of the cracking inner cylinder 201, the return material spiral 205 can timely shovel the heat carrier into it, so as to reversely transport the heat carrier in the return material spiral 205 to the head of the cracking inner cylinder 201 as much as possible. The end point of the return material spiral 205 is provided with a gap with the head of the cracking inner cylinder 201, so that when the heat carrier reaches the end point of the return material spiral 205, there is enough space for the heat carrier to be squeezed into the central area of the cracking inner cylinder 201 and to be forwardly transported to the tail together with the material, so as to realize the circulation of the heat carrier in the cracking inner cylinder 201. Specifically, the starting point of the return material spiral 205 is located at the position of the drum screen 206 at the tail of the cracking inner cylinder 201, that is, the heat carrier shoveling port, and the side surface of the heat carrier shoveling port is attached to the material blocking ring 207. The end point is located in the arrangement area of the spiral guide plate 202 at the head of the cracking inner cylinder 201, that is, the heat carrier discharging port.

[0036] The drum screen 206 is a curved strip screen with strip-shaped screen holes, has a larger effective screening area, and has the same inner diameter as the cracking inner cylinder 201. The two are rigidly connected. The drum screen 206 is provided with a material blocking ring 207 at the tail. The material blocking ring 207 is an open circular plate, which prevents the hot carrier from overflowing and plays a cofferdam role, and at the same time allows the pyrolysis oil gas to be discharged through the opening of the material blocking ring 207. In order to prevent pyrolysis carbon from blocking the screen surface, a vibration knocking device is also installed on the back of the drum screen 206 to remove the pyrolysis carbon blocking the screen holes.

[0037] The outer flue 3 is a hollow cylindrical cavity structure, which is coaxially sleeved with the cracking inner cylinder 201 through a flue sealing device 8. The flow direction of the flue gas in the outer flue 3 is opposite to the conveying direction of the material in the cracking inner cylinder 201. The outer wall of the outer flue 3 is a steel shell, and the inner wall is paved with refractory castable.

[0038] The kiln tail cover 4 is installed at the tail of the cracking inner cylinder 201. The axial length of the cover shell should ensure that the drum screen 206 is completely contained therein. The cracking inner cylinder 201 is connected through an oil gas sealing device 7. The upper part is a pyrolysis oil gas outlet, and the lower part is a pyrolysis carbon outlet.

[0039] The oil gas sealing device 7 and the flue gas sealing device 8 are both rotary sealing devices. The two oil gas sealing devices 7 are respectively located at the connection positions of the screw feeder 1 and the cracking inner cylinder 201, and the connection positions of the cracking inner cylinder 201 and the kiln tail cover 4. The two flue gas sealing devices 8 are respectively located at the two connection positions of the outer wall flue and the cracking inner cylinder 201.

[0040] The material pyrolysis process of the rotary pyrolysis device is as follows:

[0041] S1: After being crushed and dried, the material is sent into the cracking inner cylinder 201 by the screw feeder 1, and is mixed with high-temperature heat carrier particles that are returned to the furnace head by the return material screw 205 and are reheated. In this process, the material is rapidly heated and undergoes rapid pyrolysis reaction under the combined heating of the high-temperature flue gas in the outer flue 3 and the contact heating of the high-temperature heat carrier, and is converted into pyrolysis oil gas (containing tar and non-condensable olefins and hydrocarbons) and pyrolysis carbon.

[0042] S2: During the operation of the rotary pyrolysis device, the cracking inner cylinder 201 is placed on the supporting device 6 composed of a roller, a blocking wheel, a bearing, etc. by a roller, and rotates around the axis of the cracking inner cylinder 201 at a low speed under the drive of the transmission device 5. At this time, the mixed material entering the furnace will be transported to the furnace tail under the combined action of the guide screw plate, the material lifting plate 203 and the inclined cracking inner cylinder 201.

[0043] S3: Due to the pressure differential between the inside and outside of the cracking drum 201, the pyrolysis oil and gas escape through the mesh of the drum screen 206 and the retaining ring 207, and are discharged from the pyrolysis oil and gas outlet on the upper part of the kiln hood 4 to the rotary pyrolysis unit. The pyrolytic char and heat carrier mixture, as the cracking drum 201 rotates, is conveyed to the screen surface of the drum screen 206 for screening and separation. The fine pyrolytic char passes through the mesh and becomes the undersize material, which is discharged from the rotary pyrolysis unit through the pyrolytic char outlet on the lower part of the kiln hood 4. The coarse heat carrier becomes the oversize material, which is blocked by the retaining ring 207 and stagnates at the end of the drum screen 206.

[0044] S4: The return screw 205, welded to the wall, rotates synchronously with the cracking inner cylinder 201. During this process, the return screw 205 shovels in the heat carrier that has stopped at the tail end of the drum screen 206 every time the cracking inner cylinder 201 rotates one circle. The heat carrier shoveled into the return screw 205 is then returned to the head of the cracking inner cylinder 201 by the reverse spiral conveying action of the return screw 205. During the return process, the heat carrier is heated by the high-temperature flue gas in the external flue 3 in the return screw 205, causing the heat carrier to be reheated and finally sent to the furnace head of the cracking inner cylinder 201, where it is mixed with the fresh material input through the screw feed device 1 to start the next round of material pyrolysis process.

[0045] The rotary pyrolysis device of the present invention adopts an integrated internal and external heat material heating method, which optimizes the heat transfer method by combining the inter-wall heat transfer of high-temperature flue gas with the direct contact heat transfer of high-temperature circulating heat carrier, thereby improving the heating uniformity and pyrolysis rate of the material in the furnace while reducing the generation of non-condensable products such as tar in the pyrolysis products.

[0046] The heat carrier added to the rotary pyrolysis device of the present invention will collide and impact the inner wall of the cracking inner cylinder 201 under the throwing action of the lifting plate 203, thereby removing the coke in the cylinder.

[0047] The rotary pyrolysis device of the present invention integrates the return screw 205 and the drum screen 206 internally, so that the rotary pyrolysis device assumes the screening, return and reheating functions of the heat carrier, thereby eliminating the complex external screening, transportation, lifting, reheating and other equipment required by traditional internal heating pyrolysis devices. It has the advantages of a short process flow, small equipment investment, and low system energy consumption.

[0048] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that falls within the scope defined by the claims of the present invention falls within the scope of protection of the present invention.

Claims

1. An internal and external heat integrated rotary pyrolysis device with an internal return mechanism, characterized by: The invention comprises a supporting device, a cracking inner cylinder (201), a transmission device (5), a kiln tail hood (4), a spiral feeding device (1) for conveying materials, and an external flue (3) for introducing flue gas, wherein the cracking inner cylinder (201) is rotatably connected to the supporting device, the output end of the transmission device (5) is connected to the cracking inner cylinder (201), the external flue (3) is sleeved on the cracking inner cylinder (201), the outlet end of the spiral feeding device (1) is rotatably connected to one end of the cracking inner cylinder (201), and the other end of the cracking inner cylinder (201) is rotatably connected to the kiln tail hood (4); the cracking inner cylinder (201) is arranged obliquely, a drum screen (206) is provided at a section of the cracking inner cylinder (201) extending into the kiln tail hood (4), a heat carrier is loaded in the cracking inner cylinder (201), and a return spiral (205) for returning the heat carrier is provided on the inner wall of the cracking inner cylinder (201); During the process of the material being rotated and transported from the head to the tail of the cracking inner cylinder (201), the rotation direction of the return screw (205) causes the heat carrier to be transported in the reverse direction from the tail of the cracking inner cylinder (201) to the head; there is no gap between the starting point of the return screw (205) and the tail of the cracking inner cylinder (201), and there is a gap between the end point of the return screw (205) and the head of the cracking inner cylinder (201); A plurality of material lifting plate groups are arranged axially on the inner wall of the cracking inner cylinder (201), and the material lifting plate groups include a plurality of material lifting plates (203) uniformly distributed along the circumference of the inner wall of the cracking inner cylinder (201); A material retaining ring (207) for retaining the heat carrier is installed at the tail of the drum screen (206), and an opening for discharging pyrolysis oil and gas is provided on the material retaining ring (207).

2. The internal and external heat integrated rotary pyrolysis device with an internal material return mechanism according to claim 1, characterized in that: The inclination angle of the cracking inner cylinder (201) is 1° to 5°.

3. The internal and external heat integrated rotary pyrolysis device with an internal material return mechanism according to claim 1, characterized in that: A spiral material guide plate (202) is provided on the inner wall of the furnace head of the cracking inner cylinder (201).

4. The internal and external heat integrated rotary pyrolysis device with an internal material return mechanism according to claim 1, characterized in that: The drum screen (206) has a curved surface structure, and the screen holes of the drum screen (206) are in the shape of strips.

5. The internal and external heat integrated rotary pyrolysis device with an internal material return mechanism according to claim 1, characterized in that: A flue gas guide plate (204) is provided on the outer wall of the cracking inner cylinder (201). The flue gas guide plate (204) is located in the external flue (3). The flue gas guide plate (204) is in a spirally wound installation form, and the spiral rise angle of the flue gas guide plate (204) is between 30° and 60°.

6. The internal and external heat integrated rotary pyrolysis device with an internal material return mechanism according to claim 1, characterized in that: The cross section of the return spiral (205) is rectangular, triangular or trapezoidal, and the spiral angle of the return spiral (205) is 30° to 60°.

7. The internal and external heat integrated rotary pyrolysis device with an internal material return mechanism according to claim 1, characterized in that: Oil and gas sealing devices (7) are provided at the connection positions between the spiral feeding device (1) and the cracking inner cylinder (201), and at the connection positions between the cracking inner cylinder (201) and the kiln tail cover (4), and flue gas sealing devices (8) are provided at two connection positions between the outer wall flue and the cracking inner cylinder (201).

8. The internal and external heat integrated rotary pyrolysis device with an internal material return mechanism according to any one of claims 1 to 7, characterized in that: A vibration device for removing pyrolytic carbon blocking the screen holes is installed on the back of the drum screen (206).

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