Internal and external heat integrated rotary pyrolysis device with internal material returning mechanism

Abstract

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

Description

Technical Field

[0001] The invention belongs to the technical field of pyrolysis devices, and in particular relates to an internal and external heat integrated rotary pyrolysis device with an internal material return mechanism. Background Art

[0002] Low-temperature anaerobic pyrolysis of organic solid waste is a process in which the organic macromolecular components in organic solid waste break down in an oxygen-free or oxygen-deficient environment to produce small molecular gases, tars and residues. Low-temperature anaerobic pyrolysis technology for organic solid waste can not only achieve the harmlessness, reduction and resource utilization of organic solid waste, obtain multiple products such as pyrolysis oil and gas, pyrolysis carbon, but also effectively overcome the dioxin problem caused by incineration, and is an effective treatment method. At present, common external heating rotary pyrolysis devices mostly use high-temperature flue gas generated by the combustion of gas or pyrolysis oil and gas to transfer heat to the materials in the pyrolysis furnace through the metal wall. This inter-wall heat transfer method has problems such as poor heat transfer performance, uneven heating of materials in the furnace, and uncontrollable pyrolysis products. In addition, coking is prone to occur during the pyrolysis of organic solid waste. 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 reduces the economic efficiency of equipment operation. In severe cases, it may even cause equipment damage and accidents.

[0003] The problems of poor thermal conductivity and easy coking during the pyrolysis process have become important issues restricting the long-term economic, stable and safe operation of pyrolysis furnaces, and they need to be improved urgently. Summary of the invention

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

[0005] The technical solution adopted by the present invention is:

[0006] An internal and external heat integrated rotary pyrolysis device with an internal return mechanism comprises a support device, a cracking inner cylinder, a transmission device, a kiln tail cover, a screw feed device for conveying materials and an external flue for introducing flue gas, the cracking inner cylinder is rotatably connected to the support 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 screw feed device is rotatably connected to one end of the cracking inner cylinder, and the other end of the cracking inner cylinder is rotatably connected to the kiln tail cover; the cracking inner cylinder is arranged obliquely, and the cracking inner cylinder is extended to the outer end of the kiln tail cover. A drum screen is arranged at a section of the kiln tail cover, a heat carrier is loaded in the cracking inner cylinder, and a return screw for returning the heat carrier is arranged on the inner wall of the cracking inner cylinder; when the material is 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 reversely transported 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).

[0007] 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, improves the heating uniformity and pyrolysis rate of the material in the furnace, and reduces the formation of non-condensable products such as tar in the pyrolysis products. The heat carrier can also play a role in removing coke on the inner wall of the cracking inner cylinder under the action of the lifting plate.

[0008] The rotary pyrolysis device of the present invention integrates a return spiral and a drum screen 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 heat pyrolysis devices. It has the advantages of short process flow, small equipment investment, and low system energy consumption.

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

[0010] As a preferred solution of the present invention, a spiral guide plate is provided at the inner wall of the furnace head of the cracking inner cylinder. The spiral guide plate is a short spiral plate group circumferentially welded to the inner wall of the furnace head of the cracking inner cylinder, and the rotation direction is determined by the rotation of the cracking inner cylinder to advance the material.

[0011] As a preferred solution of the present invention, a plurality of lifting plate groups are axially arranged on the inner wall of the cracking inner cylinder, and the lifting plate group includes a plurality of lifting plates uniformly distributed along the circumference of the inner wall of the cracking inner cylinder.

[0012] As a preferred embodiment of the present invention, the drum screen is a curved structure, and the screen holes of the drum screen are in the shape of slits.

[0013] As a preferred embodiment of the present invention, a flue gas guide plate is provided on the outer wall of the cracking inner cylinder. The flue gas guide plate is located in the external flue and is installed in a spiral winding manner. The spiral angle of the flue gas guide plate is between 30° and 60°.

[0014] As a preferred solution of the present invention, a material retaining ring for blocking the heat carrier is installed at the tail of the drum screen, and an opening is provided on the material retaining ring for discharging pyrolysis oil and gas.

[0015] As a preferred embodiment of the present invention, the cross-section of the return spiral is rectangular, triangular or trapezoidal, and the helix angle of the return spiral is 30° to 60°.

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

[0017] As a preferred embodiment of the present invention, a vibration device for removing pyrolytic carbon blocking the screen holes is installed on the back of the drum screen.

[0018] The beneficial effects of the present invention are:

[0019] 1. 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, improves the heating uniformity and pyrolysis rate of the material in the furnace, and reduces the formation of non-condensable products such as tar in the pyrolysis products. The heat carrier can also play a role in removing coke on the inner wall of the cracking inner cylinder under the action of the lifting plate.

[0020] 2. The rotary pyrolysis device of the present invention integrates a return spiral and a drum screen 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 the traditional internal heat pyrolysis device, and has the advantages of short process flow, small equipment investment, and low system energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 is a cross-sectional view of a portion of the structure of the present invention;

[0023] Figure 3 It is a schematic diagram of the structure of the return spiral;

[0024] Figure 4 It is a structural diagram of the retaining ring.

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

[0026] In order to make the purpose, 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 in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 here 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 merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0028] like Figure 1 to Figure 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 obliquely, and a section of the cracking inner cylinder 201 extending into the kiln tail hood 4 is provided with a drum screen 206, 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.

[0029] 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 tilted with an angle of 1° to 5°. It can be made of high temperature and corrosion resistant stainless steel materials such as 309S or 310S. The inner wall is also equipped with a spiral guide plate 202 and a lifting plate 203, which respectively play the role of pushing the material forward, preventing the material from flowing back and spilling the material, and enhancing the mixing.

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

[0033] The lifting plate 203 is a metal plate formed by welding two flat plates into an angled shape, and the angle between the two flat plates is 120° to 150°. The lifting plates 203 are evenly arranged around the inner wall of the ring cracking inner cylinder 201 to form a group, and multiple lifting plate groups are evenly arranged along the axial direction of the cracking inner cylinder 201, and two adjacent groups of lifting plates 203 are staggered.

[0034] The flue gas guide plate 204 is arranged on the outer wall of the cracking inner cylinder 201, and is installed in a spiral winding form, with a spiral angle between 30° and 60°, which plays a role in forcing the flue gas to flow, increase the flue gas flow rate, and enhance heat and mass transfer. In addition, there is a height gap of about 15 to 50 mm between the top of the flue gas guide plate 204 and the inner wall of the external flue 3 to accommodate equipment processing and installation errors and thermal expansion and contraction.

[0035] The return spiral 205 is a hollow channel with a rectangular cross section (it can also be designed as a triangle or trapezoid), which is arranged along the inner wall of the cracking inner cylinder 201 and spirally wound against the wall. The spiral angle is 30° to 60°, and the direction of rotation should ensure that the material in the return 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. There is no gap between the starting point of the return spiral 205 and the tail of the cracking inner cylinder 201. When the mixture of heat carrier and material is transported from the center of the cracking inner cylinder 201 to the tail of the cracking inner cylinder 201, the return spiral 205 can shovel the heat carrier into it in time, so that the heat carrier can be reversely transported to the head of the cracking inner cylinder 201 in the return spiral 205 as much as possible. There is a gap between the end point of the return screw 205 and the head of the cracking inner cylinder 201, so that when the heat carrier reaches the end point of the return screw 205, there is enough space for it to be squeezed into the central area of ​​the cracking inner cylinder 201, and it is forwardly transported to the tail along 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 screw 205 is located at the drum screen 206 at the tail of the cracking inner cylinder 201, that is, the heat carrier shoveling port, and the side of the heat carrier shoveling port is in contact with the baffle ring 207, and the end point is located at the arrangement area of ​​the spiral guide plate 202 at the head of the cracking inner cylinder 201, that is, the discharge port of the heat carrier.

[0036] The drum screen 206 is a curved strip-shaped screen with a slot-shaped screen hole, which has a larger effective screening area. The inner diameter of the drum screen 206 is the same as that of the cracking inner cylinder 201, and the two are rigidly connected. A retaining ring 207 is installed at the tail of the drum screen 206. The retaining ring 207 is an open-hole circular plate, which prevents the heat carrier from overflowing and acts as a cofferdam. At the same time, the pyrolysis oil and gas can be discharged through the opening of the retaining ring 207. In order to prevent the pyrolytic carbon from clogging the screen surface, a vibration device is also installed on the back of the drum screen 206 to remove the pyrolytic carbon blocking the screen hole.

[0037] The external flue 3 is a hollow cylindrical cavity structure, which is connected to the coaxial sleeve of the cracking inner cylinder 201 through a flue gas sealing device 8. The flue gas flow direction in the external flue 3 is opposite to the material conveying direction in the cracking inner cylinder 201. The outer wall of the external flue 3 is a steel shell, and the inner wall is covered with refractory insulation casting material.

[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 can be included as a whole. It is connected to the cracking inner cylinder 201 through the oil and gas sealing device 7. The upper part is the pyrolysis oil and gas outlet, and the lower part is the pyrolysis carbon outlet.

[0039] The oil and gas sealing device 7 and the flue gas sealing device 8 are both rotary sealing devices. The two oil and gas sealing devices 7 are respectively located at the connection position between the spiral feeding device 1 and the cracking inner cylinder 201, and the connection position between 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 between 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: The crushed and dried material is fed into the cracking inner cylinder 201 by the screw feeding device 1, and mixed with the high-temperature heat carrier particles that are sent back to the furnace head and reheated by the return screw 205. In this process, the material is heated rapidly and undergoes a rapid thermal cracking reaction under the combined heating of the high-temperature flue gas inter-wall heat exchange in the external flue 3 and the high-temperature heat carrier contact heat transfer, 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 supporting wheel, a retaining wheel, a bearing, etc. through a roller ring, and is driven by the transmission device 5 to perform low-speed rotary motion around the axis of the cracking inner cylinder 201. At this time, the mixed material entering the furnace will be transported to the tail of the furnace under the joint action of the material guide spiral plate, the material lifting plate 203 and the inclined cracking inner cylinder 201.

[0043] S3: The pyrolysis oil and gas escape through the screen holes of the drum screen 206 and the retaining ring 207 under the action of the pressure difference between the inside and outside of the cracking inner cylinder 201, and are discharged from the rotary pyrolysis device from the pyrolysis oil and gas outlet at the top of the kiln tail cover 4. The pyrolysis carbon and heat carrier mixture are transported to the screen surface of the drum screen 206 for screening and separation as the cracking inner cylinder 201 rotates. The fine particles of pyrolysis carbon pass through the screen holes to become undersize, and are discharged from the rotary pyrolysis device through the pyrolysis carbon outlet at the bottom of the kiln tail cover 4. The coarse particles of heat carrier become oversize, which are blocked by the retaining ring 207 and stagnate at the tail end of the drum screen 206.

[0044] S4: The return screw 205 welded against the wall rotates synchronously with the cracking inner cylinder 201. During this process, the return screw 205 shovels the heat carrier staying at the tail end of the drum screen 206 once for each rotation of the cracking inner cylinder 201. The heat carrier shoveled into the return screw 205 is returned to the head of the cracking inner cylinder 201 under the reverse spiral conveying action of the return screw 205. During the return process, the heat carrier is heated by the partition wall of the high-temperature flue gas in the external flue 3 in the return screw 205, so that the heat carrier is reheated and finally sent to the furnace head of the cracking inner cylinder 201 to mix with the fresh material input through the spiral feeding device 1 to carry out 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 carriers, thereby improving the heating uniformity and pyrolysis rate of the materials in the furnace and 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 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 the traditional internal heat pyrolysis device, and has the advantages of 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 various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. An internal and external heat integrated rotary pyrolysis device with an internal material return mechanism, characterized in that: The invention comprises a supporting device, a cracking inner cylinder (201), a transmission device (5), a kiln tail cover (4), a spiral feed 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 feed 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 cover (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 cover (4), a heat carrier is loaded in the cracking inner cylinder (201), and a material return spiral (205) for returning the heat carrier is provided on the inner wall of the cracking inner cylinder (201); When the material is rotated and transported from the head to the tail of the cracking inner cylinder (201), the rotation direction of the return spiral (205) causes the heat carrier to be reversely transported from the tail of the cracking inner cylinder (201) to the head; there is no gap between the starting point of the return spiral (205) and the tail of the cracking inner cylinder (201), and there is a gap between the end point of the return spiral (205) and the head of the cracking inner cylinder (201).

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 arranged 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: 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 circumferential direction of the inner wall of the cracking inner cylinder (201).

5. 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) is a curved structure, and the screen holes of the drum screen (206) are in the shape of slits.

6. 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 arranged 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. The spiral rise angle of the flue gas guide plate (204) is between 30° and 60°.

7. The internal and external heat integrated rotary pyrolysis device with an internal material return mechanism according to claim 1, characterized in that: A material blocking ring (207) for blocking the heat carrier is installed at the tail of the drum screen (206), and an opening is provided on the material blocking ring (207) for discharging pyrolysis oil and gas.

8. 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 material return spiral (205) is rectangular, triangular or trapezoidal, and the spiral angle of the material return spiral (205) is 30° to 60°.

9. 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 position between the spiral feeding device (1) and the cracking inner cylinder (201), and at the connection position between the cracking inner cylinder (201) and the kiln tail cover (4), and smoke sealing devices (8) are provided at two connection positions between the outer wall flue and the cracking inner cylinder (201).

10. The internal and external heat integrated rotary pyrolysis device with an internal material return mechanism according to any one of claims 1 to 9, 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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