A novel asphalt preheating and drying device

Abstract

This invention relates to a novel preheating and drying device for recycled asphalt, comprising an elevator. The top discharge end of the elevator is connected to the top of a vertical drying tower, and the lower part of the vertical drying tower is connected to a hot air furnace. Multiple sets of conical cylinders and truncated cone guide plates are alternately arranged from top to bottom inside the vertical drying tower. The walls of the conical cylinders are evenly distributed with several air film pores. The conical cylinders inside the vertical drying tower are connected in series by support pipes. This invention employs a counter-current heat exchange process, with hot air supplied from the lower part of the vertical drying tower from bottom to top, and the recycled material moving from top to bottom by gravity. Combined with structural optimization to control the cross-sectional wind speed inside the tower, it reduces the escape of fine RAP particles carried by the hot air, lowers the load on the dust removal system, and reduces aggregate gradation loss. It can stably achieve low-temperature preheating of RAP recycled material, with a target discharge temperature of 80℃. It only removes surface moisture from the material, achieving dust removal pretreatment without causing extensive melting and aging of the asphalt, thus meeting the process positioning of pre-treatment in asphalt recycling stations.

Description

Technical Field

[0001] This invention relates to the technical field of hot recycling equipment for asphalt pavement, specifically a novel preheating and drying device for asphalt waste. Background Technology

[0002] Plant-mixed hot recycling processes require heating the recycled asphalt. When the addition ratio exceeds 70%, a preheating drum is necessary for material dehydration, dust removal, and preheating; otherwise, the temperature and quality of the recycled material cannot be guaranteed when adding it at extremely high proportions. The current mainstream preheating equipment is a horizontal recycling drying drum, which relies on the rotation of the drum to drive the lifting plates to turn the material and complete heat exchange. This type of equipment is large and heavy, requiring matching motors, rollers, bearings, and other rotating drive components, resulting in high equipment costs and high energy consumption. Ordinary vertical drying towers for sand and gravel aggregates rely on gravity discharge and counter-current hot air heat exchange. They have a compact structure with no rotating parts. While those skilled in the art hope to adapt them for the pretreatment of RAP recycled materials, direct application has several drawbacks: 1. RAP contains aged asphalt. In the 70-80℃ preheating range, the asphalt enters the initial softening stage, making it easy for materials to adhere to the guiding components inside the tower, gradually forming scale and accumulating, blocking the material flow channels, losing heat exchange capacity, and hindering continuous production. Conventional single stainless steel liners and ordinary chain sliding have limited anti-sticking effects, and the chains themselves can also adhere to the asphalt recycled material. 2. Most existing drying equipment is used for deep high-temperature drying of aggregates and lacks a complete design as a pretreatment unit for asphalt recycling equipment, failing to achieve only the process objectives of surface dehydration and dust removal, and low-temperature preheating. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a novel asphalt preheating and drying device, which is a vertical preheating drying device with a compact structure, low energy consumption, anti-sticking and clogging, and capable of stably preheating RAP to 80°C.

[0004] To achieve the above objectives, the present invention provides a novel preheating and drying device for asphalt waste, comprising an elevator, the top discharge end of which is connected to the top of a vertical drying tower, the lower part of which is connected to a hot air furnace, multiple sets of conical cylinders and truncated cone guide plates alternately arranged from top to bottom inside the vertical drying tower, the conical cylinder walls being evenly distributed with several air film holes, the conical cylinders inside the vertical drying tower being connected in series by support pipes; the truncated cone guide plates are lined with polished stainless steel plates and equipped with high-frequency vibrators; the support pipes are connected to the hot air furnace through air supply pipelines.

[0005] In addition, the novel asphalt waste preheating and drying device proposed in the above embodiments of the present invention may also have the following additional technical features: As a further improvement of the present invention, the top of the hot blast stove is connected to a chimney via an induced draft fan.

[0006] As a further improvement of the present invention, the feed inlet of the elevator is equipped with a conveyor belt and a cold hopper.

[0007] As a further improvement of the present invention, the hot air temperature output by the hot air furnace is 80 to 100 degrees Celsius.

[0008] As a further improvement of the present invention, the gas supply pressure of the hot blast furnace is controlled to be 0.3-0.8 MPa.

[0009] As a further improvement of the present invention, the diameter of the air film holes in the conical cylinder is 1.5 to 3 millimeters, and the air film holes are arranged in an array along the circumferential and axial directions of the side wall of the conical cylinder.

[0010] As a further improvement of the present invention, the truncated cone guide plate is installed inside the vertical drying tower through an elastic vibration damping and isolation component.

[0011] By means of the above-described solution, the present invention has at least the following advantages: This device adopts a vertical tower structure, eliminating the need for large rotating drum drive components. The overall structure is compact, occupies a small area, and has lower equipment investment and operating energy consumption than traditional horizontal regeneration drying drums.

[0012] 2. A combination structure of a conical cylinder and a frustum-shaped guide plate is used to disperse recycled materials, increase the contact area between the material and hot air, and improve heat exchange efficiency. The conical cylinder has air film vents to introduce 80-100℃ gas, forming an air film isolation layer. The frustum-shaped guide plate, combined with high-frequency vibration and a stainless steel lining, works synergistically to prevent sticking. These multiple methods inhibit asphalt adhesion and scaling, ensuring continuous equipment operation.

[0013] 3. A counter-current heat exchange process is adopted, in which hot air is sent from the bottom of the tower and flows upward, while the recycled material moves downward by gravity. Combined with structural optimization to control the wind speed in the tower section, the escape of fine RAP particles carried by hot air is reduced, the load on the dust removal system is reduced, and the loss of aggregate gradation is reduced.

[0014] 4. It can stably achieve low-temperature preheating of RAP recycled material, with the discharge temperature controlled at a target of 80℃. It only removes surface moisture from the material to achieve dust removal pretreatment, without causing a large amount of asphalt to melt and age, thus meeting the process positioning of pretreatment in asphalt recycling stations.

[0015] 5. The entire set of equipment is connected to the existing recycled material feeding and conveying link, with strong adaptability to modification. The pre-treated material is directly supplied to the downstream asphalt recycling equipment, and the process connection is smooth. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a new type of asphalt waste preheating and drying device. Figure 2This is a schematic diagram of a vertical drying tower structure for a new type of asphalt waste preheating and drying device; In the diagram: 1. Chimney, 2. Exhaust fan, 3. Vertical drying tower, 4. Hot air furnace, 5. Elevator, 6. Conveyor belt, 7. Cold hopper, 8. High-frequency vibrator, 9. Conical cylinder, 10. Conical truncated guide plate, 11. Support pipe. Detailed Implementation

[0017] The present invention provides a novel asphalt preheating and drying device with reference to the accompanying drawings.

[0018] In Embodiment 1 of this application, as Figure 1 and Figure 2 As shown, this novel asphalt preheating and drying device (hereinafter referred to as "the present invention") includes a hoist 5, the inlet of which is equipped with a conveyor belt 6 and a cold hopper 7. The top outlet of the hoist 5 is connected to the top of a vertical drying tower 3, and the lower part of the vertical drying tower 3 is connected to a hot air furnace 4. Multiple sets of conical cylinders 9 and truncated cone guide plates 10 are alternately arranged from top to bottom inside the vertical drying tower 3. The walls of the conical cylinders 9 are evenly distributed with several air film holes. The conical cylinders 9 inside the vertical drying tower 3 are connected in series by support pipes 11. The support pipes 11 are connected to the hot air furnace 4 through an air supply pipeline. The air supply pipeline is equipped with an air source pressure regulating valve and a temperature regulating unit to introduce low-pressure clean gas at 80-100℃ into the conical cylinders 9. A continuous thin-layer isolation gas film is formed on the surface, with a film thickness maintained at 1-2 mm. This film isolates the falling recycled material particles from the conical metal wall, preventing softened asphalt from directly adhering to the conical wall. The gas supply pressure is controlled at 0.3-0.8 MPa. If the gas supply pressure is below 0.3 MPa, the injection volume is insufficient, and a complete continuous gas film cannot be formed. If the gas supply pressure is above 0.8 MPa, the airflow disturbance is too large, which will disrupt the hot air field inside the tower and exacerbate the entrainment of fine material by flue gas, causing the gas to be ejected outward through the gas film holes. The conical guide plate 10 is lined with a polished stainless steel plate and equipped with a high-frequency vibrator 8. The high-frequency vibrator 8 drives the conical guide plate 10 to perform high-frequency micro-amplitude vibration, with a vibration frequency of 15-30 Hz and an amplitude of 0.5-2 mm. This disrupts the bonding interface between the recycled asphalt and the plate surface, and works in conjunction with the stainless steel lining to achieve anti-sticking. The material slides down the conical guide plate. The top of the hot blast stove 4 is connected to the chimney 1 via an induced draft fan 2. The gas supply pressure of the hot blast stove 4 is controlled at 0.3-0.8 MPa.

[0019] This embodiment 2 is basically the same as the structure of embodiment 1. The difference is that the diameter of the air film hole of the conical cylinder 9 is 1.5 to 3 mm, and the air film holes are arranged in an array along the circumferential and axial directions of the side wall of the conical cylinder 9.

[0020] To further optimize the working efficiency of this application, the hot air temperature output by the hot air furnace 4 is between 80 and 100 degrees Celsius. If the supply air temperature is below 80 degrees Celsius, it will have a cooling effect on the material inside the tower, affecting the preheating effect; if the supply air temperature is above 100 degrees Celsius, it will locally aggravate the softening of RAP asphalt, thus increasing the risk of material sticking. The hot air furnace 4 is an indirect hot air furnace, avoiding direct contact between the flame and the recycled material, and the hot air output temperature is adjustable. The conical guide plate 10 is installed inside the vertical drying tower 3 through an elastic vibration damping isolation component to prevent vibration from being transmitted to the shell of the vertical drying tower.

[0021] Once a new type of asphalt waste preheating and drying device is installed, the equipment can be put into use.

[0022] When in use, this invention works as follows: In operation, the material cart pours the material into the cold hopper 7, which then gradually falls onto the conveyor belt 6. The conveyor belt 6 transports the material to the feed inlet of the elevator 5. The elevator 5 lifts the material to the feed inlet at the top of the vertical drying tower 3, where it falls into the tower. The hot air furnace 4 provides hot air through a burner. The hot air in the vertical drying tower 3 is supplied by the hot air furnace 4 connected to the bottom. The hot air flows upward from the bottom of the tower, while the recycled material falls downward by gravity. The hot air and the recycled material come into countercurrent contact to complete heat exchange. Multiple temperature sensors are arranged along the height inside the vertical drying tower 3. The temperature sensors, hot air furnace 4, elevator 5, and conveyor belt 6 are electrically connected to the control system. The control system adjusts the hot air temperature and feed rate in a closed loop based on the multi-point temperature of the vertical drying tower 3 and the temperature of the discharged material, stabilizing the temperature of the discharged recycled material at 80℃. An over-temperature interlock protection is set up. When the material temperature exceeds 90℃, the interlock increases the amount of cold air added and reduces the feed rate to prevent local overheating and asphalt melting. During the falling process of the recycled material, it is guided and dispersed by the cone cylinder 9 and the cone-shaped guide plate 10, forming a loose material flow. This increases the contact area with the upward-flowing hot air, achieving heat exchange, dehydration, and dust removal. The material is preheated to the target temperature of 80°C. After processing, the recycled material is discharged from the bottom outlet of the vertical drying tower and sent to the downstream asphalt recycling equipment for subsequent production.

[0023] The vertical drying tower 3 is equipped with a tail gas emission interface at the top of the tower, and the tail gas is connected to the dust removal system of the mixing plant. By controlling the wind speed at the cross section of the tower to 0.6-1.2m / s, the ability of the upward airflow to carry fine recycled material particles is reduced, thereby reducing the loss of fine materials.

[0024] In summary, this invention provides a novel asphalt preheating and drying device. This device employs a vertical tower structure, eliminating the need for large rotating drum drive components. The overall structure is compact, occupying a small area, and its investment and operating energy consumption are lower than traditional horizontal recycling drying drums. By combining a conical cylinder 9 and a truncated cone guide plate 10, the recycled material is dispersed, increasing the contact area between the material and hot air, thus improving heat exchange efficiency. The conical cylinder 9 has air film vents, allowing the introduction of 80-100°C gas to form an air film isolation layer. The truncated cone guide plate 10, combined with high-frequency vibration and a stainless steel lining, works synergistically to prevent asphalt adhesion and scaling, ensuring continuous operation of the equipment. A counter-current heat exchange process is used, with hot air introduced from the bottom of the vertical drying tower 3, flowing upwards, while the recycled material moves downwards due to gravity. Combined with structural optimization to control the wind speed within the tower cross-section, this reduces the escape of fine RAP particles carried by the hot air, lowering the load on the dust removal system and reducing aggregate gradation losses. It can stably achieve low-temperature preheating of RAP recycled materials, with a discharge temperature control target of 80℃. It only removes surface moisture from the material to achieve dust removal pretreatment, without causing a large amount of asphalt melting and aging, thus meeting the process positioning of pretreatment in asphalt recycling stations.

[0025] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity. Any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A novel asphalt waste preheating and drying device, comprising a hoist (5), characterized in that, The top discharge end of the elevator (5) is connected to the top of the vertical drying tower (3), and the bottom of the vertical drying tower (3) is connected to the hot air furnace (4). Multiple sets of conical cylinders (9) and truncated cone guide plates (10) are alternately arranged from top to bottom inside the vertical drying tower (3). Several air film holes are evenly distributed on the wall of the conical cylinder (9). The conical cylinders (9) inside the vertical drying tower (3) are connected in series by support pipes (11). The truncated cone guide plate (10) is lined with polished stainless steel plate and equipped with a high-frequency vibrator (8). The support pipe (11) is connected to the hot air furnace (4) through the air supply pipeline.

2. The novel asphalt waste preheating and drying device according to claim 1, characterized in that, The top of the hot air furnace (4) is connected to the chimney (1) via an induced draft fan (2).

3. The novel asphalt waste preheating and drying device according to claim 2, characterized in that, The feed inlet of the elevator (5) is equipped with a conveyor belt (6) and a cold hopper (7).

4. The novel asphalt waste preheating and drying device according to claim 1, characterized in that, The hot air temperature output by the hot air furnace (4) is between 80 and 100 degrees Celsius.

5. The novel asphalt waste preheating and drying device according to claim 4, characterized in that, The gas supply pressure of the hot air furnace (4) is controlled at 0.3-0.8 MPa.

6. The novel asphalt waste preheating and drying device according to claim 1, characterized in that, The diameter of the air film holes in the conical cylinder (9) is 1.5 to 3 mm, and the air film holes are arranged in an array along the circumferential and axial directions of the side wall of the conical cylinder (9).

7. The novel asphalt waste preheating and drying device according to claim 1, characterized in that, The truncated cone guide plate (10) is installed inside the vertical drying tower (3) through an elastic vibration damping isolation component.

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