A heating device of a drum-type low-vacuum high-efficiency energy-saving drying equipment

Abstract

The utility model discloses a kind of heating device of drum type low-vacuum high-efficiency energy-saving drying equipment, belong to drying equipment heating technical field.The device includes coiled setting in the inner spiral heating pipe of central shaft part inside and coiled setting in the outer spiral heating pipe of its outside, and the inner and outer spiral heating pipe is connected through pipeline and forms the heat medium flow path of series connection.Optimally, heat medium flow path can be further extended to the interlayer of barrel system.The utility model is multiplied by the unique layout of inside and outside double spiral heating pipe, and heat exchange area is doubled, and the step efficient utilization of thermal energy from center to edge is realized, fundamentally solve the problem of the limited heat exchange area of traditional drum dryer, and the problem of low thermal efficiency, and energy-saving effect is remarkable.

Description

Technical Field

[0001] This utility model relates to the field of heating technology for drying equipment, and in particular to a high-efficiency conductive heating device for drum-type vacuum drying equipment. Background Technology

[0002] Traditional rotary drum dryers rely on a single heating method, typically only introducing a heat medium through the drum's jacket or using a simple heating tube along the central shaft. This limited heat exchange area becomes a bottleneck for improving drying efficiency. For materials with high moisture content, the limited heat contact surface results in long drying times and high energy consumption. Some equipment uses hot air convection heating, but this is ineffective in a vacuum environment and leads to significant heat loss. Therefore, there is an urgent need for a heating solution that can provide a large and efficient heat exchange area in a vacuum environment. Utility Model Content

[0003] The purpose of this utility model is to provide a heating device with a large heat exchange area, high thermal efficiency, and reasonable structure, which is specifically used in drum-type low vacuum high efficiency energy-saving drying equipment.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A heating device for a drum-type low-vacuum high-efficiency energy-saving drying equipment includes an inner spiral heating tube coiled inside a central shaft assembly and an outer spiral heating tube coiled outside the central shaft assembly. The inner and outer spiral heating tubes are connected by a pipeline to form a series heat medium flow path.

[0006] Preferably, the outer spiral heating tube is in contact with or integrated with the shaftless outer spiral heat-conducting part mounted on the central shaft.

[0007] Preferably, the heat medium flow path extends further into the interlayer of the cylinder system, such that the heat medium flows through the inner spiral heating pipe into the outer spiral heating pipe, and then from the outer spiral heating pipe into the interlayer of the cylinder system.

[0008] Preferably, the inner spiral heating tube is welded and fixed to the central tube mounted on the central shaft.

[0009] Preferably, the heating device is connected to an external heat source via a steam rotary joint.

[0010] The beneficial effects of this utility model are:

[0011] This invention utilizes an inner and outer double-helix heating tube design to heat the material from both the inside and outside, increasing the heat exchange area by more than three times compared to traditional structures, thus greatly improving heating capacity and drying speed. The heat medium flows sequentially through the inner helix tube, outer helix tube, and cylinder jacket, with the temperature decreasing step by step, achieving tiered and efficient utilization of thermal energy and significant energy-saving effects. The outer helix heating tube is integrated with the shaftless outer helix, serving as both a material-propulsing mechanism and a heating surface, combining two functions in a compact structure. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of the drying equipment of this utility model;

[0013] Figure 2 This is a cross-sectional view of the overall structure of the drying equipment of this utility model;

[0014] Figure 3 This is a schematic diagram of the central shaft assembly of this utility model;

[0015] Figure 4 This is a schematic diagram of the floating sealing structure of this utility model;

[0016] As shown in the diagram: 10. Central shaft assembly; 1010. Feed screw; 1020. Prestressed tension rod; 1030. Inner spiral heating tube; 1040. Outer spiral heating tube; 1050. Lifting plate; 1060. Shaftless outer spiral; 1070. Central tube; 1080. Discharge screw; 1090. Anchor end; 1100. Prestressed tensioning end; 20. Main cylinder welded component; 30. Input cylinder assembly; 40. Discharge cylinder assembly; 50. Discharge floating seal; 60. Sealing window; 70. Swinging rotary seal; 80. Main drive chain. 90. Main motor sprocket; 100. Fixed bearing assembly; 110. Self-aligning bearing assembly; 120. Discharge motor sprocket; 130. Main drive motor tensioning seat; 140. Discharge motor tensioning seat; 150. Feed inlet; 160. Discharge outlet; 170. Spacer; 180. Steam outlet; 190. Drain outlet; 200. Vacuum pump inlet and outlet; 210. Vacuum and dehumidification steam inlet; 220. Sealing body; 230. Cavity sealing end; 240. End seal; 250. Rotary seal; 260. Sealing body pressure plate. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0018] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] In the description of this utility model, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0020] like Figure 1-4 The heating device of the drum-type low-vacuum high-efficiency energy-saving drying equipment shown includes:

[0021] Shell system:

[0022] The cylindrical system mainly consists of a main cylinder welded component 20, an input cylinder assembly 30, and an output cylinder assembly 40, which are connected by flange seals to form a sealed, elongated cylindrical space capable of withstanding negative pressure. It can be evacuated to a negative pressure state. The main cylinder welded component 20 has a double-layer jacket structure, and its inner wall itself constitutes a basic heat exchange surface. The single cylinder shown in the figure can be replaced with a double cylinder in actual use.

[0023] Central shaft assembly 10:

[0024] The central shaft is rotatably mounted inside the cylindrical system and is driven by a drive device;

[0025] The drive unit includes a main drive motor, which transmits power to the central shaft assembly 10 through the main motor sprocket 90, chain, and main drive sprocket 80, driving it to rotate.

[0026] The two ends of the central shaft assembly 10 are supported by the fixed bearing assembly 100 and the self-aligning bearing assembly 110, respectively, wherein the self-aligning bearing can compensate for installation errors and thermal expansion of the shaft.

[0027] A prestressed structure with a central shaft assembly of 10:

[0028] The central shaft assembly includes a prestressed tensioning component. For example... Figure 3As shown, the prestressed tensioning assembly includes a prestressed tension rod 1020, an inner spiral heating tube 1030, an outer spiral heating tube 1040, a lifting plate 1050, a shaftless outer spiral 1060, and a central tube 1070. Two central tubes 1070 are connected by flanges to form the main shaft of the central shaft assembly 10. The inner spiral heating tube 1030 is welded and fixed onto it. The prestressed tension rod 1020, the shaftless outer spiral 1060, the lifting plate 1050, and the outer spiral heating tube 1040 are welded together to form a central shaft assembly, which is fitted onto the outside of the connected central tube 1070. The prestressed tension rod 1020 and the central tube 1070 are arranged parallel to each other.

[0029] Both ends of the prestressed tension rod 1020 are fixed by adjustable connectors. The end located on one side of the discharge screw 1080 is fixedly connected by an anchoring end connector, and the central shaft welding piece is initially positioned and fixed to the central tube 1070. The end located on one side of the feed screw 1010 is fixed by a prestressed tensioning end, and a specific gap is pre-set between the two connecting flanges of this prestressed tensioning end. By tightening the connecting bolts here according to the specified torque and sequence, the gap is eliminated, thereby forcing the prestressed tension rod 1020 to elastically elongate, thereby generating a set prestress within it.

[0030] One end of the prestressed tension rod 1020 is fixed by the anchoring end 1090, and the other end is fixed by the prestressing tensioning end (with a preset gap between the two flanges). The gap is eliminated by tightening the bolts of the prestressing tensioning end 1100, which causes the prestressed tension rod 1020 to elastically elongate and generate prestress.

[0031] Because the shaftless outer spiral 1060 and the outer spiral heating tube 1040 of the central shaft welding component have relatively low strength (the shaftless outer spiral 1060 has no central connecting support, and the outer spiral heating tube 1040 requires a thin heat-conducting pipe), they will deform under stress during operation. After the prestressed tension rod 1020 is tightened by bolts connecting the two gap flanges, the prestressed tension rod 1020 elongates and generates prestress inside, thus enhancing its resistance to bending. The resistance to bending of the prestressed tension rod 1020 and the deformation resistance of the discharge spiral 1080 connected to it under stress are greatly enhanced. With the connection of the lifting plate 1050, the overall stress resistance and deformation resistance are greatly improved. This design significantly enhances the rigidity and deformation resistance of the entire assembly, especially the cantilevered shaftless outer spiral 1060 and the outer spiral heating tube 1040, under high-speed rotation and heating conditions.

[0032] Sealing system:

[0033] A floating sealing structure is provided between the cylindrical system and the central shaft assembly. This structure, together with the swing rotary seal 70 and the discharge floating seal 50, forms a composite sealing system, achieving a dual sealing mechanism. This ensures a reliable seal between the central shaft assembly 10 and the stationary cylindrical system in a vacuum environment.

[0034] like Figure 4 As shown, the floating seal structure includes a sealing cavity fixed to the cylindrical system; a sealing body 150 sleeved on the central shaft assembly 10, which can have slight radial and axial floating displacement relative to the sealing cavity; at least two rotary seals with skeleton oil seals are installed inside the sealing body 150 to ensure the rotational sealing of the main shaft; the sealing plate 160 fixes the end seal to the sealing end of the sealing cavity, the sealing plate restricts the rotation of the sealing body, and there is an end face seal between the end seal and the sealing end of the cavity and the sealing body (and there is a gap within the elastic deformation range of the seal; therefore, the rotation of the main shaft is sealed by the rotary seal, and the up-down and left-right floating of the main shaft or the sealing end of the cavity is sealed by the end face seal). This design realizes a dual sealing mechanism. The rotation of the central shaft assembly 10 is controlled by the swing rotary seal 70 formed by the rotary seal; while the floating of the main shaft or cavity due to thermal deformation and manufacturing errors is compensated by the discharge floating seal 50 formed by the end seal. This ensures the long-term sealing reliability of the equipment under complex working conditions.

[0035] A sealed viewing window 60 is installed at an appropriate location in the cylinder system to observe the internal material conditions.

[0036] Heating system:

[0037] The heating system provides a conductive heat source, including an inner spiral heating tube 1030 coiled around the surface of the central tube 1070 and an outer spiral heating tube 1040 coiled around the outside of the central tube 1070. The outer spiral heating tube 1040 is in thermal contact with or integrated with the shaftless outer spiral 1060. The flow path of the heat medium (such as steam) is as follows: it flows sequentially through the inner spiral heating tube 1030, the outer spiral heating tube 1040, and finally enters the interlayer of the main cylinder welded component 20. This design significantly increases the total heat exchange area compared to traditional drum dryers.

[0038] Two sets of spiral heating tubes are arranged on the central shaft part 10: inner spiral heating tube (small diameter, small axial thrust) and outer spiral heating tube (large diameter, supported by the shaftless outer spiral and the lifting plate).

[0039] Through the above design, the total heat exchange area can be more than three times that of a traditional drum dryer (such as the 25㎡ of the GGI20X40). At the same time, due to the sealed space, the internal gas is heated and also becomes a heat source, further improving the heat exchange efficiency.

[0040] Vacuum and dehumidification system:

[0041] It communicates with the internal space of the cylindrical system and is used to extract moisture and maintain a vacuum.

[0042] The vacuum and dehumidification system is designed with a maximum vacuum level of -0.08 MPa and a normal operating vacuum level of -0.05 MPa. At this vacuum level, the boiling point of water drops to approximately 80°C, significantly increasing the evaporation rate of water.

[0043] The system is equipped with a vacuum pump, which can evacuate the sealed space after feeding and maintain the set vacuum level during the drying process to accelerate the escape of moisture.

[0044] The vacuuming and dehumidification system includes a two-position four-way solenoid valve. By switching the valve position, the inlet and outlet of the vacuum pump can be switched to the cylinder system or an external air source, respectively, to achieve the functions of vacuuming and controlled vacuum breaking.

[0045] Feeding and discharging system: Located at both ends of the cylinder system and equipped with gate valves for sealing.

[0046] Specifically, feeding: wet material enters through the feed inlet 150 and falls into the input cylinder section 30 under gravity. The central shaft section 10 is rotated by the main motor, and the feeding screw 1010 on it pushes the material into the main drying space.

[0047] Conveying and Turning: A shaftless external spiral 1060 is installed on the central shaft assembly 10 via a prestressed tension rod 1020. The distance between the shaftless external spiral 1060 and the inner wall of the main cylinder welded part 20 is no more than 1mm, which is used to push the material close to the cylinder wall towards the discharge end. Since the shaftless external spiral 1060 is not high and is equipped with lifting plates 1050, the material is continuously lifted and thrown down during the forward movement, forming a reverse flow, achieving full mixing and thermal contact.

[0048] Discharge control: The discharge screw 1080 is connected to the central shaft 10. During the drying process, the excessive accumulation of material at the discharge end can be counteracted by reversing the screw; after drying, the material can be discharged from the discharge port 160 by reversing the screw.

[0049] The discharge motor is mounted on the discharge motor tensioning seat 140. Through the discharge motor sprocket 120 and chain, it independently drives the discharge screw 1080 to achieve individual control of the discharge speed.

[0050] A drying method for a drying device includes the following steps:

[0051] S1. Preheating stage:

[0052] A heat medium is introduced into the heating system within the drying cylinder system to preheat the interior of the cylinder system;

[0053] Specifically, the saturated steam that meets the requirements is fed into the drying cylinder system through the steam rotary joint at the feed end. The inner spiral heating tube 1030 and outer spiral heating tube 1040 distributed within the drying cylinder system heat the sealed space. After the steam is collected, it enters the middle layer of the main cylinder welded part through the steam rotary joint at the discharge end and the inner wall of the cylinder through the spacer 170. Finally, the steam is collected at the steam outlet 180 and the condensate outlet 190 for energy recovery.

[0054] At this time, the external channels for dehumidification and vacuuming are open to ensure the thermal expansion of the gas. It should be noted that the system operates continuously; this description only applies to the cold-running operation. When the system operates continuously, there is a certain temperature inside the system when discharge is complete, and the system will also raise the ambient temperature to the specified requirements before feeding.

[0055] S2. Feeding and mixing preheating stage:

[0056] While maintaining communication between the inside of the cylinder system and the external environment, wet material is fed into the cylinder system, and the central shaft is driven to rotate, causing the material to move and come into contact with the hot surface for preheating.

[0057] Specifically, the material is fed into the drying space and dried at a specified temperature (with system temperature balance control). Since it is impossible to fill the space with material all at once during feeding, vacuuming is neither necessary nor possible. Specifically, the central shaft assembly 10 rotates, opening the inlet valve 150, allowing the material to enter the input cylinder assembly 30 under gravity. The feeding screw 1010 on the rotating central shaft assembly 10 feeds the material into the drying space, while the shaftless external screw 1060 on the central shaft assembly 10 propels the material forward. The lifting plates 1050 on the rotating central shaft assembly 10 lift the material to a certain position, where it falls due to gravity, ensuring full contact between the material and hot air. Because the central shaft assembly 10 has a discharge screw 1080, the material does not enter the discharge cylinder assembly 40 at this time. The material accumulates at the discharge screw 1080 of the central shaft assembly 10 due to obstruction. After a certain amount of material has been fed or after a certain time, the vacuum pump is activated for dehumidification.

[0058] When the material moves in a circular motion, it generates centrifugal force, which causes the material to adhere tightly to the inner wall of the cylinder. The lifting plates 1050 on the central shaft 10 drive the material to move in a circular motion. When the centrifugal force is too large, the material will not fall; when the centrifugal force is too small, the material cannot be fully lifted. At this time, we need to control the centrifugal acceleration of the circular motion as close as possible to the acceleration due to gravity. Since the centrifugal force is different at different parts of the material, we need to control the speed of the central shaft 10 to ensure that the lifting plates 1050 lift the material fully before it falls. Specifically, the motor is controlled by a frequency converter, and the speed of the central shaft 10 is adjusted by a reducer so that the centrifugal acceleration generated when the material is lifted by the lifting plates is controlled within the range of 0.8g to 1.2g.

[0059] S3. Sealed vacuum main drying stage:

[0060] After the feed reaches the predetermined requirements, the equipment is sealed and the vacuum system is activated to bring the cylinder system to a set negative pressure state and maintain it. During this stage, the central shaft unit 10 is continuously driven to rotate to stir the material and continuously provide heat to the material through the heating system until the material is dried to the target moisture content.

[0061] Specifically, material continuously enters the drying space. Once the designated amount is reached, the inlet gate valve 150 is closed, along with the outlet gate valve 160 and the vacuum and dehumidification steam inlet valve 210. At this point, the internal system space is sealed. Vacuuming is then performed, and the vacuum level is balanced once the designated vacuum level is reached. This is the main drying period, and a two-stage heating and drying process can be adopted. Initially, the temperature and vacuum level are set higher, then lowered (depending on the characteristics of the material being dried).

[0062] Theoretically, when the amount of material to be dried is small, it will all accumulate in front of the discharge cylinder section 40. Even with a large amount and a low external spiral 1060 on the central shaft section 10 (with lifting plates 1050), the material still tends to accumulate in front of the discharge cylinder section 40, resulting in less material at the inlet 150 and more material at the outlet 160. The solution is to reverse the rotation of the discharge spiral 1080, giving the material a force in the direction of the input cylinder section 30. Specifically, after feeding is complete, start the discharge spiral 1080 on the central shaft section 10 to reverse it, pushing the material in the opposite direction over a large area.

[0063] Temperature and humidity control are crucial during the drying stage. Once the vacuum level is determined, temperature becomes the most important means of controlling moisture escape, and temperature control is achieved through wet-bulb temperature control. Specifically, after all the material enters the drying space, there is a certain period of heating due to the material being at room temperature. Once the wet-bulb temperature reaches the specified value, temperature equilibrium is achieved by adjusting the steam flow rate. Of course, vacuuming and maintaining the vacuum level continue until the wet-bulb temperature reaches the specified level. Controlling the humidity, temperature, and vacuum level only controls the drying speed. To ensure the dried material meets the drying requirements, a microwave moisture meter and near-infrared spectroscopy are introduced. Specifically, the microwave moisture meter periodically measures the moisture content of the material being dried, and drying is complete when the material reaches the specified moisture content.

[0064] S4. Vacuum breaking and material discharge stage:

[0065] After drying is complete, stop the vacuuming process and fill the cylinder system with gas to restore the internal pressure to atmospheric or near-atmospheric pressure. Then, discharge the dried material.

[0066] When warm materials are rapidly degaussed, the sudden pressure drop can cause a sharp decrease in boiling point, leading to violent boiling and material splashing. Therefore, it is necessary to controllably release the vacuum. Specifically, this is done by changing the direction of the vapor flow using a two-position four-way solenoid valve, switching the vacuum pump inlet and outlet ports 200 from pumping to charging. After releasing the vacuum, the outlet valve 160 is opened, and the discharge screw 1080 on the central shaft assembly 10 is started to discharge the material.

[0067] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present utility model. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A heating device for a drum-type low-vacuum high-efficiency energy-saving drying equipment, characterized in that, include: The inner spiral heating tube (1030) is coiled inside the central shaft assembly (10). The outer spiral heating tube (1040) is coiled around the outside of the central shaft part (10). The inner spiral heating tube (1030) and the outer spiral heating tube (1040) are connected by a pipeline to form a series heat medium flow path.

2. The heating device according to claim 1, characterized in that, The outer spiral heating tube (1040) is in thermal contact with or integrated with the shaftless outer spiral (1060) on the central shaft assembly (10).

3. The heating device according to claim 1, characterized in that, The heat medium flow path extends further into the interlayer of the cylinder system, such that the heat medium flows through the inner spiral heating tube (1030) into the outer spiral heating tube (1040), and then from the outer spiral heating tube (1040) into the interlayer of the cylinder system.

4. The heating device according to claim 1, characterized in that, The inner spiral heating tube (1030) is welded and fixed to the central tube (1070) of the central shaft assembly (10).

5. The heating device according to claim 1, characterized in that, The heating device is connected to an external heat source via a steam rotary joint.

Images