Drying equipment and drying control method

Abstract

The invention discloses drying equipment and a drying control method. The drying equipment comprises a machine shell and a conveying mechanism arranged in the machine shell. The waste gas discharging system comprises a waste gas discharging pipe set and an exhaust fan, and the waste gas discharging pipe set is composed of a front-section discharging pipeline, a middle-section discharging pipeline and a rear-section discharging pipeline which are sequentially arranged in the material conveying direction; the circulating air system comprises a circulating air pipeline and a circulating fan, an inlet of the circulating air pipeline is connected to the rear-section discharging pipeline, and an outlet of the circulating air pipeline serves as a front-stage drying air opening; the hot air supply system comprises a fresh air pipeline, a fresh air fan and a heating device, and an outlet of the fresh air pipeline serves as a rear-stage drying air opening; materials on the conveying mechanism pass through the front-stage drying air opening and the rear-stage drying air opening in sequence. The fresh air proportion is reduced by introducing waste gas circulation, and the heating energy consumption of the drying line and the auxiliary fuel consumption of the rear-end waste gas treatment device are effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of processing equipment technology, and in particular to drying equipment and drying control methods. Background Technology

[0002] As a core heat exchange component in air conditioning and other refrigeration equipment, the performance of the radiator directly affects the energy efficiency of the entire system. During the manufacturing process, radiators undergo precision machining such as copper tube bending and aluminum foil stamping. These processes require a large amount of processing oil to ensure molding quality. However, the oil residue remaining on the surface of the copper tubes and aluminum foil after machining can severely hinder heat conduction; therefore, it must be removed through a drying process. The residual oil rate is a key indicator of drying quality and typically needs to be controlled below 0.3% to meet the thermal conductivity requirements of the radiator.

[0003] Currently, the industry generally uses tunnel-type drying ovens for continuous processing. For example... Figures 1 to 2 As shown, the radiator enters from the head of the furnace and is conveyed sequentially through the drying line by the transport mechanism 2. The hot air supply system 5 blows hot air into the transport mechanism 2, using the hot air to evaporate the processing oil and carry it away by the airflow. The exhaust gas generated during drying is sent to the subsequent exhaust gas treatment device for treatment through the exhaust gas emission system 3. To ensure that the residual oil rate meets the standards, the existing process generally adopts a ventilation design with large air volume and high air velocity. Although this extensive process can basically meet the quality requirements, it has a significant energy consumption problem: the drying line itself needs to consume a large amount of natural gas to heat the air and generate hot air to dry the radiator. Moreover, due to the large volume of hot air, the oil and gas concentration in it is not high (generally around 800 mg / m³). This gas is mostly treated by RTO (regenerative thermal oxidizer). The low oil and gas concentration requires the RTO to increase the amount of natural gas used for combustion to ensure the combustion temperature and treatment effect of the RTO.

[0004] Therefore, how to design drying equipment and drying control methods that can effectively utilize waste gas and reduce hot air volume is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] To address the shortcomings of existing technologies, such as high energy consumption and low energy utilization, this invention proposes a drying equipment and drying control method. By introducing waste gas recirculation to reduce the proportion of fresh air, while ensuring the key quality indicator of radiator residual oil rate, it effectively reduces the heating energy consumption of the drying line itself and the auxiliary fuel consumption of the downstream waste gas treatment device, thus achieving a balance between product quality and energy-saving benefits.

[0006] The technical solution adopted in this invention is to design a drying device, including:

[0007] The housing and the transport mechanism housed within the housing;

[0008] An exhaust gas emission system includes an exhaust gas emission pipe assembly and an exhaust fan. The exhaust gas emission pipe assembly consists of a front-end emission pipe, a middle-end emission pipe, and a rear-end emission pipe arranged sequentially along the material transport direction.

[0009] The circulating air system includes a circulating air duct and a circulating fan. The inlet of the circulating air duct is connected to the downstream discharge duct, and the outlet of the circulating air duct serves as the pre-drying air outlet.

[0010] The hot air supply system includes a fresh air duct, a fresh air fan, and a heating device. The outlet of the fresh air duct serves as the drying air outlet for the subsequent stage.

[0011] The materials on the transport mechanism pass through the pre-drying air inlet and the post-drying air inlet in sequence.

[0012] The inner cavity of the casing is divided into a front drying zone, a middle drying zone, and a rear drying zone along the material transport direction. The front drying air outlet is located in the front drying zone, and the rear drying air outlet is located in the middle and rear drying zones.

[0013] Furthermore, both the circulating air duct and the downstream exhaust duct are equipped with air valves for adjusting the air volume.

[0014] Furthermore, the drying equipment also includes:

[0015] The VOC concentration detection device is installed in the downstream emission pipeline to detect the VOC concentration value in the exhaust gas in real time.

[0016] The control system is electrically connected to the VOC concentration detection device, the circulating fan, and the air valve.

[0017] Furthermore, the VOC concentration detection device is located upstream of the air inlet of the air valve.

[0018] Furthermore, the heating device uses a gas-fired heating system.

[0019] In some embodiments, the material is a heat sink.

[0020] This invention also proposes a drying control method, which is applied to the aforementioned drying equipment and includes:

[0021] The actual VOC concentration value X of the downstream emission pipeline was detected;

[0022] Determine whether the actual VOC concentration value X is within the target concentration range;

[0023] If so, then keep the actual circulating air volume A of the circulating air duct unchanged;

[0024] If not, adjust the actual circulating air volume A of the circulating air duct according to the actual VOC concentration value.

[0025] Furthermore, adjusting the actual airflow of the circulating air duct according to the actual VOC concentration includes:

[0026] When the actual VOC concentration X is higher than the upper limit of the target concentration range X1, the actual circulating air volume A of the circulating air duct is reduced according to the first calculation formula.

[0027] When the actual VOC concentration X is lower than the lower limit of the target concentration range X2, the actual circulating air volume A of the circulating air duct is increased according to the second calculation formula;

[0028] The first calculation formula is: A = A0 - (X - X1) × B1, and the second calculation formula is: A = A0 + (X2 - X) × B2; A0 is the initial circulating air volume, and B1 and B2 are both adjustment coefficients.

[0029] Furthermore, drying control methods also include:

[0030] The actual fresh air volume of the fresh air duct is adjusted synchronously with the actual circulating air volume A. When the actual circulating air volume A increases by ΔA, the actual fresh air volume decreases by ΔA. When the actual circulating air volume A decreases by ΔA, the actual fresh air volume increases by ΔA.

[0031] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0032] 1. By introducing exhaust gas recirculation to reduce the proportion of fresh air, the heating energy consumption of the drying line itself and the auxiliary fuel consumption of the downstream exhaust gas treatment device are reduced while ensuring the drying quality indicators, thus achieving the core goal of energy conservation and consumption reduction.

[0033] 2. A closed-loop control system based on exhaust gas concentration was established to dynamically optimize the ratio of circulating air to fresh air. This ensured drying quality (residual oil rate) while minimizing the amount of fresh air introduced, significantly reducing the overall energy consumption of the drying equipment and subsequent exhaust gas treatment devices. Attached Figure Description

[0034] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein:

[0035] Figure 1 This is a schematic diagram of the structure of a traditional drying equipment;

[0036] Figure 2 This is a schematic diagram of the gas flow direction in traditional drying equipment;

[0037] Figure 3 This is a schematic diagram of the drying equipment of the present invention;

[0038] Figure 4 This is a schematic diagram of the gas flow direction of the drying equipment of the present invention;

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Machine casing; 11. Feeding end; 12. Discharging end;

[0041] 2. Transportation agencies;

[0042] 3. Exhaust gas emission system; 31. Front-end emission pipeline; 32. Mid-end emission pipeline; 33. Rear-end emission pipeline; 34. Exhaust fan; 35. Exhaust gas damper; 36. VOC concentration detection device;

[0043] 4. Circulating air system; 41. Circulating air duct; 42. Circulating fan; 43. Pre-drying air outlet; 44. Circulating air valve;

[0044] 5. Hot air supply system; 51. Fresh air duct; 52. Heating device; 53. Post-drying air outlet;

[0045] 6. Materials. Detailed Implementation

[0046] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0047] like Figures 3 to 4 As shown, the drying equipment proposed in this invention includes: a housing 1, a transport mechanism 2, an exhaust gas emission system 3, a circulating air system 4, and a hot air supply system 5.

[0048] The transport mechanism 2 is located inside the housing 1 and is used to transport the material 6 from the loading end 11 to the unloading end 12 of the housing 1. A linear transport mechanism such as a belt conveyor can be used.

[0049] The exhaust gas emission system 3 includes an exhaust gas emission pipe assembly and an exhaust fan 34. The exhaust gas emission pipe assembly consists of a front exhaust pipe 31, a middle exhaust pipe 32, and a rear exhaust pipe 33 arranged sequentially along the material transport direction. The front exhaust pipe 31 is close to the loading end 11 of the casing 1, and the rear exhaust pipe 33 is close to the unloading end 12 of the casing 1. When the exhaust fan 34 is turned on, it draws the exhaust gas in the casing 1 through the exhaust gas emission pipe assembly and sends it to the subsequent exhaust gas treatment device.

[0050] The circulating air system 4 includes a circulating air duct 41 and a circulating fan 42. The inlet of the circulating air duct 41 is connected to the downstream discharge duct 33, and the outlet of the circulating air duct 41 serves as the pre-drying air outlet 43. The pre-drying air outlet 43 is close to the feeding end 11 of the casing 1. Since the downstream discharge duct 33 is close to the unloading end 12 of the casing 1, the concentration of volatile organic compounds (VOCs) inside it is relatively low.

[0051] The radiator entering the drying equipment is cold and has a high oil content, requiring gentle and continuous heating to allow the oil to evaporate steadily. Although the temperature of the exhaust gas in the later stage has decreased, it is still much higher than room temperature, with lower VOC concentration and humidity. This provides just the right amount of preheating and initial drying for the radiator at the feeding end 11. This avoids high-temperature shocks and ensures a smooth start to the drying process, laying a good foundation for subsequent deep drying and fundamentally helping to reduce the final residual oil rate. Moreover, the exhaust gas in the later stage carries a large amount of heat energy invested in the drying process. Redirecting this exhaust gas back to the front stage for reuse is equivalent to building an internal heat recovery circulation path, reducing the consumption required to heat the fresh air. Furthermore, since the circulating air duct 41 uses exhaust gas with a low VOC concentration, the average VOC concentration of the exhaust gas that will eventually be discharged into the subsequent exhaust gas treatment device (such as RTO) will be higher. This is beneficial to the operation of the exhaust gas treatment device because a higher concentration of VOC means better self-ignition, which can significantly reduce the natural gas consumption required to maintain the combustion temperature, thereby further reducing the total operating cost of the system.

[0052] The hot air supply system 5 includes a fresh air duct 51, a fresh air fan, and a heating device 52. When the fresh air fan is turned on, air outside the casing 1 enters the fresh air duct 51. After being heated by the heating device 52, the hot air is blown from the outlet of the fresh air duct 51 onto the material on the conveyor mechanism 2. The outlet of the fresh air duct 51 serves as the downstream drying air outlet 53. The material on the conveyor mechanism 2 passes through the upstream drying air outlet 43 and the downstream drying air outlet 53 in sequence. The material 6 first passes through the upstream drying air outlet 43 for preheating and initial drying, and then passes through the downstream drying air outlet 53 for deep drying.

[0053] This design reduces the proportion of fresh air by introducing exhaust gas recirculation, thereby reducing the heating energy consumption of the drying line itself and the auxiliary fuel consumption of the downstream exhaust gas treatment device while ensuring drying quality indicators, thus achieving the core goal of energy conservation and consumption reduction.

[0054] Specifically, the inner cavity of the casing 1 is divided into a front drying zone, a middle drying zone, and a rear drying zone along the material transport direction. The front drying zone is equipped with a front exhaust port connected to the front exhaust pipe 31, the middle drying zone is equipped with a middle exhaust port connected to the middle exhaust pipe 32, and the rear drying zone is equipped with a rear exhaust port connected to the rear exhaust pipe 33. The inlet of the front exhaust pipe 31 is connected to the front drying zone through the front exhaust port, the inlet of the middle exhaust pipe 32 is connected to the middle drying zone through the middle exhaust port, and the inlet of the rear exhaust pipe 33 is connected to the rear drying zone through the rear exhaust port. Each zone is equipped with an exhaust pipe to ensure that the exhaust gas inside the casing 1 is quickly discharged, preventing the exhaust gas from contaminating the material and affecting the drying quality.

[0055] The pre-drying air outlet 43 is located in the front drying zone, and the post-drying air outlet 53 is located in the middle drying zone and the rear drying zone. The material 6 is preheated and initially dried by the pre-drying air outlet 43. The material then passes through the middle drying zone and the rear drying zone, and the material 6 is continuously dried by the post-drying air outlet 53 to ensure that the material 6 is thoroughly dried.

[0056] In a feasible embodiment of the present invention, both the circulating air duct 41 and the downstream discharge duct 33 are equipped with air valves for adjusting the air volume. The air valve in the circulating air duct 41 is called the circulating air valve 44, and the air valve in the downstream discharge duct 33 is called the exhaust air valve 35. In practical applications, adjusting the opening degree of the circulating air valve 44 and the exhaust air valve 35 can change the exhaust gas flow rate of the circulating air duct 41, thereby adjusting the air volume of the upstream drying air outlet 43. For example, if the VOC concentration in the downstream discharge duct 33 is too high, the exhaust gas flow rate in the circulating air duct 41 needs to be reduced, so the exhaust air valve 35 is opened wider and the circulating air valve 44 is closed smaller; if the VOC concentration in the downstream discharge duct 33 is too low, the exhaust gas flow rate in the circulating air duct 41 can be increased, so the exhaust air valve 35 is closed smaller and the circulating air valve 44 is opened wider.

[0057] Based on this, a preferred embodiment of the drying equipment further includes: a VOC concentration detection device 36 and a control system. The VOC concentration detection device 36 is installed in the downstream emission pipeline 33 to detect the VOC concentration value in the exhaust gas in real time. The control system is electrically connected to the VOC concentration detection device 36, the circulating fan 42, the circulating air valve 44, and the exhaust air valve 35. The VOC concentration detection device 36 sends the detection data to the control system, and the control system controls the working status of the circulating fan 42, the circulating air valve 44, and the exhaust air valve 35 according to the detection data. For example, if the VOC concentration in the downstream discharge pipe 33 is too high, the exhaust gas flow rate in the circulating air pipe 41 needs to be reduced. Therefore, the exhaust gas valve 35 can be opened wider and the circulating air valve 44 can be closed smaller. The exhaust gas flow rate in the circulating air pipe 41 can also be reduced by lowering the speed of the circulating fan 42. If the VOC concentration in the downstream discharge pipe 33 is too low, the exhaust gas flow rate in the circulating air pipe 41 can be increased. Therefore, the exhaust gas valve 35 can be closed smaller and the circulating air valve 44 can be opened wider. The exhaust gas flow rate in the circulating air pipe 41 can also be increased by increasing the speed of the circulating fan 42.

[0058] It should be noted that, in order to improve the efficiency of waste gas utilization, the VOC concentration detection device 36 is located upstream of the air inlet of the air valve. This position can detect the state of waste gas between the operation of the air valve, and most directly and realistically reflect the actual VOC concentration of the downstream emission pipeline 33.

[0059] The heating device 52 preferably uses a gas-fired heating device. Compared with electric heating and other methods, gas-fired heating devices are smaller in size and have a faster heating rate at the same power, ensuring that the production line can quickly reach the working temperature after startup, reducing standby time and improving production efficiency. Moreover, the unit calorific value cost of natural gas or liquefied petroleum gas is much lower than that of electricity. For industrial processes like drying that are continuously high in energy consumption, using gas as a heat source can directly reduce energy costs.

[0060] In some embodiments, material 6 is a radiator with dense fins and complex internal air ducts, and residual processing oil is distributed across its entire surface area. This invention employs a pre-drying air inlet 43 and a post-drying air inlet 53 arrangement, specifically allowing material 6 to pass through these two inlets sequentially, forming a segmented, progressive drying process. This ensures that hot air can penetrate the radiator from different angles and directions, avoiding dead zones and shadowed areas, achieving uniform and thorough drying, so that the residual oil rate of the radiator is ≤0.3%, thereby guaranteeing the radiator's thermal conductivity.

[0061] This invention also proposes a drying control method, which is applied to the aforementioned drying equipment and includes:

[0062] The actual VOC concentration value X of the downstream emission pipeline was detected;

[0063] Determine whether the actual VOC concentration value X is within the target concentration range;

[0064] If so, it means that the current circulating air volume and the material volatilization state have reached the best balance, the system is running stably and the energy efficiency is in a good state, so the actual circulating air volume A of the circulating air duct remains unchanged;

[0065] If not, it indicates that the volatile load of the material or the system operating conditions have changed, and the current air volume configuration cannot maintain the optimal balance, which poses a risk of excessive residual oil rate or energy waste. Therefore, the actual circulating air volume A of the circulating air duct should be adjusted according to the actual VOC concentration value.

[0066] This design establishes a closed-loop control system based on exhaust gas concentration feedback, dynamically adjusting the actual circulating air volume A of the circulating air duct to avoid residual oil or energy waste, and optimizing energy efficiency in real time while ensuring product quality.

[0067] Specifically, adjusting the actual air volume of the circulating air duct according to the actual VOC concentration includes:

[0068] When the actual VOC concentration X is higher than the upper limit of the target concentration range X1, the actual circulating air volume A of the circulating air duct is reduced according to the first calculation formula. The first calculation formula is: A = A0 - (X - X1) × B1, where A0 is the initial circulating air volume and B1 is the reduction adjustment coefficient.

[0069] When the actual VOC concentration X is lower than the lower limit of the target concentration range X2, the actual circulating air volume A of the circulating air duct is increased according to the second calculation formula: A = A0 + (X2 - X) × B2, where A0 is the initial circulating air volume and B2 is the increase adjustment coefficient.

[0070] This design sets the adjustment amount ΔA and the deviation amount to be directly proportional. When the VOC concentration slightly exceeds the standard, the actual circulating air volume A is slightly corrected; when the VOC concentration is severely exceeded, the actual circulating air volume A is significantly corrected. This proportional relationship ensures that the adjustment intensity is precisely matched with the severity of the problem, effectively avoiding over-adjustment or repeated oscillations.

[0071] In a preferred embodiment of the present invention, the drying control method further includes: the actual fresh air volume of the fresh air duct is synchronously adjusted according to the actual circulating air volume. When the actual circulating air volume A increases by ΔA, the actual fresh air volume decreases by ΔA; when the actual circulating air volume A decreases by ΔA, the actual fresh air volume increases by ΔA. This design, by dynamically optimizing the ratio of circulating air to fresh air, achieves the goal of minimizing the amount of fresh air introduced while ensuring drying quality (residual oil rate), significantly reducing the energy consumption of the drying equipment.

[0072] For ease of understanding, a detailed description will be given using an application example of the present invention.

[0073] A drying machine with a capacity of 180 pieces / hour has a total length of about 15 meters for the pre-drying zone, the middle drying zone, and the rear drying zone.

[0074] like Figures 1 to 2 As shown, under the traditional drying scheme, the drying air volume is approximately 12,000 m³ / H, the hot air temperature is approximately 180℃, and the gas consumption of the hot air supply system 5 is approximately 10 m³. The total air volume of the front exhaust pipe 31, the middle exhaust pipe 32, and the rear exhaust pipe 33 is also 12,000 m³ / H, and the air volume of a single exhaust port is approximately 4,000 m³ / H. The combined oil concentration of the exhaust gas is approximately 0.8 g / m³. After passing through the exhaust fan 34, the exhaust gas enters the regenerative combustion exhaust gas treatment device, which consumes approximately 12 m³ / H of gas. After this drying treatment, the residual oil rate of the radiator is approximately 0.2%.

[0075] like Figures 3 to 4 As shown, in the drying scheme of this invention, the radiator containing processing oil enters the casing 1 sequentially along the transport mechanism 2, and passes through the front drying zone, the middle drying zone, and the rear drying zone in a straight line. The heat inside the casing 1 is obtained by the combustion of natural gas. Fresh air enters the gas heating device and is burned together with natural gas to obtain high-temperature gas. The high-temperature gas is blown out from the rear drying air outlet 53 along the fresh air duct 51 and is evenly distributed in the furnace to dry the radiator. The dried exhaust gas, carrying oil vapor, is sent away by the exhaust fan 34 and enters an RTO (regenerative thermal oxidizer) or other exhaust gas treatment device for purification before being discharged.

[0076] The hot air supply system 5 has a fresh air volume of approximately 12,000 m³ / H. The fresh air is heated to 180°C by natural gas combustion. The heated fresh air is then evenly distributed in the middle drying zone and the rear drying zone through the downstream drying air outlet 53.

[0077] The initial circulating air volume of the circulating air system 4 is approximately 2000 m³ / H, and the exhaust air volume is approximately 10000 m³ / H. The circulating air is evenly distributed in the front drying zone through the pre-drying air outlet 43, and the exhaust gas enters the regenerative combustion equipment for exhaust gas treatment.

[0078] Due to the existence of gas-solid equilibrium, there is a correlation between the oil and gas content in the gaseous state and the residual oil rate on the solid. Through comparative operational practice, it was found that as long as the VOC (oil and gas) concentration in the downstream exhaust gas is below 0.1 g / m³, the residual oil rate of the dried product can be ensured to be below 0.3%. In actual operation, controlling the VOC concentration in the downstream exhaust gas between 0.6 and 0.08 g / m³ has a certain safety limit, ensuring product qualification.

[0079] That is, the target concentration range is 0.6~0.08 g / m³. If the actual VOC concentration detected by the VOC concentration detection device 36 is 0.07 g / m³, then the actual circulating air volume A does not need to be adjusted. At this time, the residual oil rate of the radiator after drying is qualified, the natural gas consumption of the hot air supply system 5 is reduced from the basic 10 m³ / h to 8.5 m³ / h, the exhaust gas emission system 3 is reduced from 12000 m³ / h in the traditional drying scheme to 10000 m³ / h, the average oil concentration of the exhaust gas discharged to the exhaust gas treatment device is increased from 0.8 g / m³ to 0.94 g / m³, and the natural gas consumption of the regenerative thermal oxidizer (RTO) is reduced from 12 m³ / h to 7.6 m³ / h. The drying equipment and the subsequent exhaust gas treatment device both have significant energy-saving effects, with a total energy saving of 5.9 m³ / h, representing an energy saving of 26.8%.

[0080] During the production process, fluctuations in the oil content of raw materials and the feeding rate will cause fluctuations in the actual VOC concentration detected by the VOC concentration detection device 36. If the oil content of the radiator increases, causing the VOC concentration detection value in the later stage to reach 0.09 g / m³, the circulating air volume will be reduced and the fresh air volume will be increased. For example, relative to the upper limit concentration value of 0.08 g / m³, for every increase of 0.001 g / m³, the circulating air volume will be reduced by 150 m³ / h and the fresh air volume will be increased by 150 m³ / h. If the oil content of the radiator decreases, causing the VOC concentration detection value in the later stage to drop to 0.05 m³ / h, the circulating air volume will be increased and the fresh air volume will be reduced. For example, relative to the lower limit concentration value of 0.06 g / m³, for every decrease of 0.001 g / m³, the circulating air volume will be increased by 100 m³ / h and the fresh air volume will be reduced by 100 m³ / h. This dynamic control method increases or decreases the fresh air volume and the circulating air volume to cope with changes in different operating conditions, thus ensuring product quality and maximizing energy-saving effects.

[0081] It should be noted that the terminology used above is for describing specific embodiments only and is not intended to limit the exemplary embodiments of the present invention. When the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. The order of execution of actions, steps, etc., in the apparatus and methods shown in the specification and drawings can be implemented in any order unless a specific order is expressly specified, and as long as the output of a previous process is not used in a subsequent process. Similar sequential terms used for ease of description do not imply that such an order must be followed.

[0082] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A drying device, characterized in that, include: The housing and the transport mechanism disposed within the housing; An exhaust gas emission system includes an exhaust gas emission pipe assembly and an exhaust fan. The exhaust gas emission pipe assembly consists of a front-end emission pipe, a middle-end emission pipe, and a rear-end emission pipe arranged sequentially along the material transport direction. A circulating air system includes a circulating air duct and a circulating fan. The inlet of the circulating air duct is connected to the downstream discharge duct, and the outlet of the circulating air duct serves as the pre-drying air outlet. A hot air supply system includes a fresh air duct, a fresh air fan, and a heating device, wherein the outlet of the fresh air duct serves as the downstream drying air outlet. The material on the transport mechanism passes through the front drying air inlet and the rear drying air inlet in sequence.

2. The drying equipment according to claim 1, characterized in that, The inner cavity of the casing is divided into a front drying zone, a middle drying zone, and a rear drying zone along the material transport direction. The front drying air outlet is located in the front drying zone, and the rear drying air outlet is located in the middle drying zone and the rear drying zone.

3. The drying equipment according to claim 1, characterized in that, Both the circulating air duct and the downstream discharge duct are equipped with air valves for adjusting the air volume.

4. The drying equipment according to claim 3, characterized in that, The drying equipment also includes: The VOC concentration detection device is installed in the downstream emission pipeline to detect the VOC concentration value in the exhaust gas in real time. The control system is electrically connected to the VOC concentration detection device, the circulating fan, and the air valve.

5. The drying equipment according to claim 4, characterized in that, The VOC concentration detection device is located upstream of the air inlet of the air valve.

6. The drying equipment according to claim 1, characterized in that, The heating device is a gas-fired heating device.

7. The drying equipment according to any one of claims 1 to 6, characterized in that, The material is a radiator.

8. A drying control method, wherein the drying control method is applied to the drying equipment according to any one of claims 1 to 7, characterized in that, include: The actual VOC concentration value X of the downstream emission pipeline was detected; Determine whether the actual VOC concentration value X is within the target concentration range; If so, then keep the actual circulating air volume A of the circulating air duct unchanged; If not, adjust the actual circulating air volume A of the circulating air duct according to the actual VOC concentration value.

9. The drying control method according to claim 8, characterized in that, Adjusting the actual air volume of the circulating air duct according to the actual VOC concentration value includes: When the actual VOC concentration value X is higher than the upper limit concentration value X1 of the target concentration range, the actual circulating air volume A of the circulating air duct is reduced according to the first calculation formula; When the actual VOC concentration value X is lower than the lower limit concentration value X2 of the target concentration range, the actual circulating air volume A of the circulating air duct is increased according to the second calculation formula; Wherein, the first calculation formula is: A = A0 - (X - X1) × B1, and the second calculation formula is: A = A0 + (X2 - X) × B2; A0 is the initial circulating air volume, and B1 and B2 are both adjustment coefficients.

10. The drying control method according to claim 8, characterized in that, The drying control method further includes: The actual fresh air volume of the fresh air duct is adjusted synchronously with the actual circulating air volume A. When the actual circulating air volume A increases by air volume ΔA, the actual fresh air volume decreases by air volume ΔA. When the actual circulating air volume A decreases by air volume ΔA, the actual fresh air volume increases by air volume ΔA.

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