Double-tower type reverse mixed flow circulation drying device with waste heat recovery function

Abstract

The utility model belongs to the technical field of drying, and particularly discloses a double-tower type reverse mixed flow circulation drying device with a waste heat recovery function, which comprises two dryers, the inside of each dryer is sequentially divided into a tempering section, a drying section and a grain discharging section from top to bottom, and an elevator is arranged between the two dryers. An exhaust pipeline and an air inlet pipeline are arranged on the two sides of the drying sections of the dryers respectively, heat pump units are arranged outside the two dryers, and the exhaust pipeline is communicated with the air inlet pipeline through the heat pump units. The air exhaust pipelines and the air inlet pipelines are arranged on the two sides of the dryers, materials and hot air reversely flow and are mixed in the dryers, the drying efficiency and the drying uniformity are improved, the elevator is arranged between the two dryers, the discharged materials are lifted and then guided back again, circulating drying of the materials is achieved, and the drying efficiency is improved. The heat pump unit is used for dehumidifying and heating warm and humid air exhausted by the dryer and recycling waste heat, deep coupling of the dryer and the air circulation system is achieved, and a double closed loop of'material circulation and hot air circulation 'is constructed.

Description

Technical Field

[0001] This utility model belongs to the field of drying technology, and in particular relates to a double-tower counter-current circulation drying device with waste heat recovery function. Background Technology

[0002] In industries such as agriculture, food processing, and chemicals, material drying is a key process to ensure the stability and quality of product storage.

[0003] In the drying of agricultural products such as grains and seeds, as well as some industrial materials, traditional continuous dryers generally adopt a single-tower structure design. This structure, with its single tower height superimposed with tempering, drying, and grain discharge sections, results in significant redundancy in the overall equipment. This not only significantly increases construction costs and maintenance difficulty, but also makes it difficult to precisely control the material's contact path and residence time with hot air as it only slowly descends in a single direction within the tower. This easily leads to uneven heating of the material, localized overheating causing quality deterioration, or incomplete drying resulting in residual moisture, severely affecting the stability of the finished product quality.

[0004] Existing dryers mostly rely on combustion furnaces for heat sources, directly heating air through fuel combustion to achieve drying. This method not only depends on non-renewable energy sources, but also results in the drying exhaust carrying a large amount of waste heat, which is directly emitted into the environment due to the lack of effective recovery devices. This leads to heat loss rates of 30%–50%, resulting in low energy efficiency. Furthermore, the dust, nitrogen oxides, sulfur dioxide, and other harmful gases and unburned particulate matter generated during the combustion process require additional complex exhaust gas treatment systems.

[0005] Therefore, the inventors dedicated themselves to designing a drying device to solve the above problems. Utility Model Content

[0006] The purpose of this utility model is to provide a dual-tower counter-current circulation drying device with waste heat recovery function, which reduces the height of the equipment and shortens the drying cycle while ensuring the uniformity of material drying, recovering waste heat, and meeting the needs of sustainable development.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0008] A dual-tower counter-current circulating drying device with waste heat recovery function includes two tower-type dryers. Each dryer is divided into a tempering section, a drying section, and a grain discharge section from top to bottom. An elevator is provided between the two dryers to lift the material discharged from the two dryers, distribute it sequentially, and guide it back. Each dryer has an exhaust duct for discharging warm and humid air from the dryer and an intake duct for supplying hot dry air on both sides of the drying section. A heat pump unit is provided outside the two dryers to dehumidify and heat the warm and humid air discharged from the two dryers to form hot dry air and recover waste heat. All exhaust ducts are connected to all intake ducts through the heat pump unit.

[0009] As an improvement of the dual-tower counter-current circulation drying device with waste heat recovery function of this utility model, the exhaust ends of the two dryers are connected to induced draft fans, and the two dryers are located between the induced draft fans and the heat pump unit.

[0010] As an improvement of the dual-tower counter-current circulation drying device with waste heat recovery function of this utility model, an air induced flange is provided at the exhaust port of the exhaust duct, and the air induced fan is connected to the dryer through the air induced flange.

[0011] As an improvement of the dual-tower counter-current circulation drying device with waste heat recovery function of this utility model, a dust collector is provided between the induced draft fan and the heat pump unit. The inlet and outlet of the dust collector are respectively connected to the induced draft fan and the heat pump unit through ventilation pipes.

[0012] As an improvement of the dual-tower counter-current circulation drying device with waste heat recovery function of this utility model, the dust collector is a cyclone dust collector, and a dust collection chamber is provided at the bottom of the dust collector.

[0013] As an improvement of the dual-tower counter-current circulation drying device with waste heat recovery function of this utility model, each of the air inlet pipes is provided with a ventilation hood, and the two dryers are respectively connected to the heat pump unit through the two ventilation hoods.

[0014] As an improvement of the dual-tower counter-current circulation drying device with waste heat recovery function of this utility model, the heat pump unit includes an evaporator, a compressor, a condenser, a first regenerator and a second regenerator. Warm and humid air enters the first regenerator for pre-cooling, and then is cooled by the evaporator to become cold and dry air. The cold and dry air flows through the first regenerator and the second regenerator in sequence for two preheatings, and finally returns to the condenser to absorb heat and rise in temperature to become hot and dry air.

[0015] The evaporator, compressor, condenser, and second regenerator are connected in a closed loop to form a refrigeration cycle. The refrigerant circulation process is as follows: the low-pressure, low-temperature gaseous refrigerant is compressed by the compressor to a high-pressure, high-temperature state, then flows through the condenser to become a medium-temperature, high-pressure liquid refrigerant, then releases heat at the second regenerator, and after throttling, becomes a low-temperature, low-pressure gas-liquid mixture, then enters the evaporator, and finally returns to the compressor to complete the cycle.

[0016] As an improvement of the dual-tower counter-current circulation drying device with waste heat recovery function of this utility model, the elevator is a bucket elevator, and the two dryers are arranged in a row with the elevator.

[0017] As an improvement of the dual-tower counter-current circulation drying device with waste heat recovery function of this utility model, the upper end of the elevator is provided with two wet grain distribution ports, the top of the two dryers are respectively provided with grain inlets, and the two wet grain distribution ports are respectively connected to the two grain inlets through distribution pipes.

[0018] As an improvement of the dual-tower countercurrent circulation drying device with waste heat recovery function of this utility model, the upper end of the elevator is also provided with a dry grain outlet, which is located between the two wet grain distribution outlets. The two distribution pipes are arranged in a figure-eight shape. The drying section is composed of multiple countercurrent drying zones, each of which is divided into upper and lower layers. The air inlet pipe is located in the lower layer of the countercurrent drying zone, and the air outlet pipe is located in the upper layer of the countercurrent drying zone.

[0019] Compared with existing technologies, this utility model's dual-tower counter-current circulation drying device with waste heat recovery function uses two tower dryers to simultaneously dry materials, reducing the height of a single tower and ensuring uninterrupted production. Exhaust and inlet ducts are installed on both sides of the dryers, causing the material inside the dryer to flow counter-currently and mix with the hot air entering the dryer, thus improving drying efficiency and uniformity. An elevator is positioned between the two dryers to lift the material discharged from both dryers, then distribute it sequentially and guide it back into the two dryers, achieving a circulating drying process between them. Simultaneously, a heat pump unit dehumidifies and heats the warm, humid air discharged from the dryers and recovers waste heat, achieving deep coupling between the dryer and the air circulation system. This constructs a dual closed loop of "material circulation + hot air circulation." The entire drying device reduces equipment height, shortens the drying cycle, ensures uniform material drying, recovers waste heat, and meets the needs of sustainable development. Attached Figure Description

[0020] Figure 1 This is a perspective view of the dual-tower counter-current circulation drying device with waste heat recovery function of this utility model;

[0021] Figure 2This is a left view of the dual-tower counter-current circulation drying device with waste heat recovery function of this utility model;

[0022] Figure 3 This is a schematic diagram illustrating the working principle of the dual-tower counter-current circulation drying device with waste heat recovery function of this utility model.

[0023] Illustration:

[0024] 1. Dryer; 2. Heat pump unit; 3. Elevator; 4. Dust collector; 5. Dust collection chamber; 6. Ventilation hood; 7. Exhaust fan; 8. Exhaust flange; 9. Ventilation pipe; 10. Distribution pipe; 11. Tempering section; 12. Drying section; 13. Bypass valve; 14. Grain discharge section; 15. Support column; 16. Wet grain distribution port; 17. Dry grain discharge port; 18. Guardrail; 19. First regenerator; 20. Evaporator; 21. Compressor; 22. Condenser; 23. Second regenerator; 24. Expansion valve; 25. Auxiliary condenser. Detailed Implementation

[0025] The embodiments of this utility model are described in detail below with reference to the accompanying drawings. The drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of this utility model.

[0026] Reference Figures 1 to 3 A dual-tower counter-current circulating drying device with waste heat recovery function includes two tower dryers 1, an elevator 3, and a heat pump unit 2. Each dryer 1 is divided into a tempering section 11, a drying section 12, and a discharge section 14 from top to bottom. The elevator 3 is located between the two dryers 1 and is used to lift the material discharged from the two dryers 1, then distribute it sequentially and guide it back. Each dryer 1 has an exhaust duct for discharging warm and humid air from the dryer 1 and an intake duct for supplying hot dry air on both sides of the drying section 12. The heat pump unit 2 is located outside the two dryers 1 and is used to dehumidify and heat the warm and humid air discharged from the two dryers 1 to form hot dry air and recover waste heat. All exhaust ducts are connected to all intake ducts through the heat pump unit 2.

[0027] Reference Figure 1 and Figure 3Two dryers 1 are arranged in a row at intervals. Each dryer 1 has a grain inlet at its top. The interior of each dryer 1 is divided into a tempering section 11, a drying section 12, and a grain discharge section 14 from top to bottom. The tempering section 11 is located at the top of the dryer 1. Its function is to slow down the heat intensity of the grain, redistribute the temperature and moisture of the grains, thereby reducing the heat and moisture stress of drying and preventing grain bursting. The drying section 12 consists of multiple counter-current drying zones, each 1m thick. Each counter-current drying zone is divided into upper and lower layers. The air inlet of the air inlet duct is located in the lower layer of the counter-current drying zone. A ventilation hood 6 is installed at the air inlet. The ventilation hood 6 is angular and its ventilation height (vertical) is 0.5m. The exhaust outlet of the exhaust duct is located in the upper layer of the counter-current drying zone. An air duct flange 8 is installed at the exhaust outlet. The air duct flange 8 is angular and its exhaust outlet is angular. The air height (vertical) is 0.5m. The internal ventilation of the drying section 12 is negative pressure induced draft. Through the reverse mixed flow duct design (hot air and material flow in opposite / cross directions), the surface moisture of the material is rapidly vaporized. At the same time, the hot dry air after waste heat recovery is used to dehumidify layer by layer, avoiding the problem of "dry outside and wet inside" in traditional drying. The grain discharge section 14 is located at the bottom of the entire dryer 1. It does not dewater and is mainly used to discharge the material from the dryer 1. It can be regarded as a tempering zone. The lower end of the grain discharge section 14 is equipped with a load-bearing support column 15. The ladders on the top and sides of the dryer 1 and the upper end of the elevator 3 are all equipped with guardrails 18.

[0028] Reference Figure 1 and Figure 2 The elevator 3 is preferably a bucket elevator (the elevator 3 can be selected from existing bucket elevators on the market, such as the bucket elevator disclosed in patent number 202320644775.7). The bucket elevator mainly uses traction components (chain / belt) to drive the bucket to circulate, and realizes the vertical conveying of materials through tail loading, vertical lifting and head unloading. Two dryers 1 and elevator 3 are arranged in a row, with elevator 3 specifically located between the two dryers 1. The head of elevator 3 is equipped with a guardrail 18. In order to transport wet grain, elevator 3 has two wet grain distribution ports 16 at its upper end. The two wet grain distribution ports 16 are respectively connected to the grain inlets at the top of the two dryers 1 through distribution pipes 10. The two distribution pipes 10 are arranged in a V-shape at an angle. In order to discharge the dried grain, elevator 3 also has a dry grain discharge port 17 at its upper end, which is located between the two wet grain distribution ports 16. When the hopper of elevator 3 is moved to the lower part, it can load the material in the discharge section 14 of the two dryers 1.

[0029] Reference Figure 1 and Figure 2 In order to increase the air flow speed inside the dryer 1 and improve the drying efficiency, the exhaust ends of the two dryers 1 are connected to the induced draft fan 7. The two dryers 1 are located between the induced draft fan 7 and the heat pump unit 2. The negative pressure environment formed by the induced draft fan 7 can force the hot airflow to penetrate the material layer.

[0030] Reference Figure 1 and Figure 2 In order to prevent dust erosion and protect the heat pump unit 2, a dust collector 4 is provided between the induced draft fan 7 and the heat pump unit 2. The inlet and outlet of the dust collector 4 are connected to the induced draft fan 7 and the heat pump unit 2 respectively through ventilation pipes 9. The dust collector 4 is preferably a cyclone dust collector, and a dust collection chamber 5 is provided at the bottom of the dust collector 4.

[0031] Reference Figures 1 to 3 The air outlet of the heat pump unit 2 is connected to one side of the drying section 12 of the two dryers 1 via ventilation hoods 6. The air inlet of the heat pump unit 2 is connected to the air outlet of the dust collector 4 via ventilation pipes 9. The heat pump unit 2 includes an evaporator 20, a compressor 21, a condenser 22, a first regenerator 19, a second regenerator 23, an expansion valve 24, a bypass valve 13, and an auxiliary condenser 25. The warm and humid air discharged from the dryer 1 enters the first regenerator 19 for pre-cooling, and then is cooled by the evaporator 20 to become cold and dry air. The cold and dry air flows through the first regenerator 19 and the second regenerator 23 for preheating twice, and finally returns to the condenser 22 to absorb heat and become hot and dry air. The evaporator 20, compressor 21, condenser 22, and second regenerator 23 are connected in a closed loop to form a refrigeration cycle. The refrigerant 23 and evaporator 20 are throttled by expansion valve 24. The low-pressure, low-temperature gaseous refrigerant is compressed by compressor 21 to a high-pressure, high-temperature state, and then flows through condenser 22 to become a medium-temperature, high-pressure liquid refrigerant. Then, it releases heat at the second regenerator 23, and after being throttled by expansion valve 24, it becomes a low-temperature, low-pressure gas-liquid mixture, and then enters evaporator 20, and finally returns to compressor 21 to complete the cycle. Since the heat generated by heat pump unit 2 is generally more than usual, if it is all used to heat the dry air, it will exceed the predetermined inlet air temperature (in order to ensure the drying quality of grain, the inlet air temperature of dryer 1 needs to be strictly controlled). Therefore, bypass valve 13 is used to control the refrigerant diversion ratio, so that a part of the refrigerant is diverted to auxiliary condenser 25 to heat other things (such as room temperature flowing water), thereby assisting the condensation process of refrigerant.

[0032] The working principle of this novel double-tower counter-current circulation drying device with waste heat recovery function is as follows:

[0033] Grain circulation process: Before drying, dryer 1 is first filled with wet grain. Then, dryer 1 is started, and the grain, under its own weight, passes sequentially from the top of dryer 1 through tempering section 11, drying section 12, and discharge section 14. When the grain reaches the bottom of dryer 1, it is sent back to the top by elevator 3 and re-enters dryer 1 for continuous circulation. During the entire circulation process, the grain passes through drying section 12 multiple times, where it comes into contact with dry air and gradually loses moisture. Because the grain in drying section 12 flows in opposite directions to the hot air, it follows the characteristic of drying and dehydration being fast at first and then slow, thus effectively improving drying efficiency. As the circulating drying process continues, the moisture content of the grain gradually decreases until it reaches the predetermined target moisture value, and is finally discharged from dryer 1.

[0034] The circulation process of dry air is as follows: Cold air from the natural environment first passes through condenser 22. During this process, the cold air absorbs heat from the refrigerant and is heated to become hot dry air. Subsequently, the hot dry air, under the action of the induced draft fan 7, enters the dryer 1 through the ventilation hood 6 and comes into contact with the grain, taking away the moisture in it and becoming warm humid air. The warm humid air leaves the dryer 1 through the induced draft flange 8 (e.g., ...). Figure 1 As shown), after being cleaned by dust collector 4, it flows into the first regenerator 19 (as shown). Figure 3 As shown in the diagram, the first regenerator 19 precools the warm and humid air and recovers some of the heat. The air then flows through the evaporator 20, which cools the warm and humid air. The gaseous water carried by the air condenses into liquid water and is removed, turning the warm and humid air into cold and dry air. After dehumidification and cooling, the cold and dry air flows through the first regenerator 19 again for the first preheating. It then flows through the second regenerator 23 for the second preheating and finally returns to the condenser 22 to absorb heat again and become hot and dry air, thus completing a complete drying, dehumidification and partial energy recovery process.

[0035] The refrigerant circulation process is as follows: First, the compressor 21 compresses the low-pressure, low-temperature gaseous refrigerant to a high-pressure, high-temperature state; then, the high-pressure, high-temperature refrigerant flows through the condenser 22, releases heat to the dry air and cools down, transforming into a medium-temperature, high-pressure liquid refrigerant; then, the refrigerant passes through the second regenerator 23, where it releases heat to complete the second preheating of the dry air, and then undergoes a throttling process through the expansion valve 24, further reducing its pressure and temperature, becoming a low-temperature, low-pressure gas-liquid mixture; finally, the refrigerant enters the evaporator 20, absorbs heat from the humid and hot air discharged from the dryer 1 to raise its temperature, and then returns to the compressor 21 to begin the next cycle.

[0036] The dual-tower counter-current circulating drying device with waste heat recovery function of this utility model has the following beneficial technical effects:

[0037] (1) The height of the double-tower circulating dryer 1 is moderate, and the drying time is short. Grains enter the dryer for drying through multiple cycles, which can effectively solve the problems of uneven heating of materials, local overheating or incomplete drying. If a fault occurs, the double-tower dryer 1 can ensure uninterrupted production, while the single-tower continuous dryer needs to be shut down for maintenance, which affects efficiency.

[0038] (2) The two wet grain dispensing ports 16 of the elevator 3 can greatly increase the discharge speed, and the elevator 3 is equipped with a dry grain discharge port 17. The dried grain can be directly transported to the grain truck or grain warehouse through the elevator 3, making the entire drying process more efficient.

[0039] (3) By combining the dryer 1 with the closed heat pump unit 2, the waste heat in the exhaust gas can be effectively recovered. The heat pump itself has the advantages of energy saving and environmental protection. Compared with traditional coal-fired and bio-particle-fired drying devices, it is more in line with the concept of energy saving, emission reduction and green development.

[0040] (4) Two regenerators are installed in the heat pump unit 2. The regenerator is installed before the evaporator 20 to pre-cool the warm and humid air discharged from the drying tower and preheat the cold and dry air leaving the evaporator 20. This design not only reduces the sensible heat of the warm and humid air and enhances the dehumidification efficiency, but also realizes the recovery and utilization of waste heat. The regenerator is installed between the condenser 22 and the expansion valve 24 to pre-cool the refrigerant at the outlet of the condenser 22 and further heat the dry air, so as to reduce the refrigerant temperature at the inlet of the expansion valve 24 and the temperature difference of the dry air at both ends of the condenser 22, which can effectively reduce the system energy loss and improve the overall performance.

[0041] This utility model is a dual-tower counter-current mixed-flow drying device with waste heat recovery function. It integrates waste heat recovery, optimizes the material drying path, and improves energy utilization efficiency. Through a dual-tower counter-current mixed-flow circulation structure design, combined with a heat pump unit 2, it achieves full recovery of exhaust gas waste heat and air circulation heating. This reduces equipment height, shortens the drying cycle, and ensures uniform material drying, meeting the needs of sustainable development.

[0042] The above-disclosed embodiments are merely preferred embodiments of the present utility model and should not be construed as limiting the scope of protection of the present utility model. Therefore, any equivalent changes made in accordance with the scope of the patent application of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A dual-tower counter-current circulating drying device with waste heat recovery function, characterized in that, The system includes two tower-type dryers. Each dryer is divided into a tempering section, a drying section, and a discharge section from top to bottom. A hoist is provided between the two dryers to lift the material discharged from the two dryers, distribute it sequentially, and guide it back. Each dryer has an exhaust duct for discharging warm and humid air from the dryer and an intake duct for supplying hot and dry air on both sides of the drying section. A heat pump unit is provided outside the two dryers to dehumidify and heat the warm and humid air discharged from the two dryers to form hot and dry air and recover waste heat. All the exhaust ducts are connected to all the intake ducts through the heat pump unit.

2. The dual-tower counter-current circulating drying device with waste heat recovery function according to claim 1, characterized in that, The exhaust ends of the two dryers are connected to induced draft fans, and the two dryers are located between the induced draft fans and the heat pump unit.

3. The double-column reverse mixed flow circulation drying device with waste heat recovery function according to claim 2, characterized in that, The exhaust duct is equipped with an exhaust flange at the exhaust port, and the exhaust fan is connected to the dryer through the exhaust flange.

4. The dual-tower counter-current circulating drying device with waste heat recovery function according to claim 2, characterized in that, A dust collector is provided between the induced draft fan and the heat pump unit. The inlet and outlet of the dust collector are respectively connected to the induced draft fan and the heat pump unit through ventilation pipes.

5. The dual-tower counter-current circulating drying device with waste heat recovery function according to claim 4, characterized in that, The dust collector is a cyclone dust collector, and a dust collection chamber is provided at the bottom of the dust collector.

6. The double-column reverse mixed flow circulation drying device with waste heat recovery function according to claim 1, characterized in that, Each of the air inlet ducts is equipped with a ventilation hood, and the two dryers are respectively connected to the heat pump unit through the two ventilation hoods.

7. The double-column reverse mixed flow circulation drying device with waste heat recovery function according to claim 1, characterized in that, The heat pump unit includes an evaporator, a compressor, a condenser, a first regenerator, and a second regenerator. Warm and humid air enters the first regenerator for pre-cooling, and then is cooled by the evaporator to become cold and dry air. The cold and dry air flows through the first regenerator and the second regenerator in sequence for two preheatings, and finally returns to the condenser to absorb heat and rise in temperature to become hot and dry air. The evaporator, compressor, condenser, and second regenerator are connected in a closed loop to form a refrigeration cycle. The refrigerant circulation process is as follows: the low-pressure, low-temperature gaseous refrigerant is compressed by the compressor to a high-pressure, high-temperature state, then flows through the condenser to become a medium-temperature, high-pressure liquid refrigerant, then releases heat at the second regenerator, and after throttling, becomes a low-temperature, low-pressure gas-liquid mixture, then enters the evaporator, and finally returns to the compressor to complete the cycle.

8. The dual-tower counter-current circulating drying device with waste heat recovery function according to claim 1, characterized in that, The elevator is a bucket elevator, and the two dryers are arranged in a row with the elevator.

9. The dual-tower counter-current circulating drying device with waste heat recovery function according to claim 1, characterized in that, The upper end of the elevator is provided with two wet grain distribution ports, and the top of the two dryers is provided with grain inlets respectively. The two wet grain distribution ports are connected to the two grain inlets respectively through distribution pipes.

10. The dual-tower counter-current circulating drying device with waste heat recovery function according to claim 9, characterized in that, The upper end of the elevator is also provided with a dry grain outlet, which is located between the two wet grain distribution outlets. The two distribution pipes are arranged in a figure-eight shape. The drying section consists of multiple counter-current drying zones, each of which is divided into upper and lower layers. The air inlet pipe is located in the lower layer of the counter-current drying zone, and the air outlet pipe is located in the upper layer of the counter-current drying zone.

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