Airflow circulating system in tobacco leaf baking chamber

Abstract

The utility model discloses an airflow circulation system in a tobacco leaf baking chamber, the airflow circulation system comprises a heat supply section and a moisture removal section, the heat supply section comprises a temperature control cabin, a mixing cabin, a shunting cabin and a baking chamber which are connected in sequence; the moisture removal section comprises a moisture removal waste heat recovery cabin and an air inlet cabin, a plurality of heat exchange tubes are arranged in the moisture removal waste heat recovery cabin, one end of each heat exchange tube is communicated with the air inlet cabin, the other end of each heat exchange tube is communicated with the outside atmosphere, and the air inlet cabin is communicated with the bottom of the curing barn; an air inlet and an air outlet are formed in the moisture removal waste heat recovery cabin, the air inlet is communicated with the outside atmosphere, and the air outlet is communicated with the temperature control cabin; a fan is arranged at the top of the temperature control cabin, gas in the temperature control cabin is promoted by the fan to enter the curing barn after passing through the mixing cabin and the shunting cabin, and flows back into the temperature control cabin from the bottom of the curing barn again to form continuous circulation, and when the humidity in the curing barn is too high, the moisture removal section is opened to remove moisture outwards, and preheating can be achieved through the heat exchange pipe.

Description

Technical Field

[0001] This utility model belongs to the field of tobacco curing, specifically relating to an airflow circulation system in a tobacco curing chamber. Background Technology

[0002] Traditional tobacco curing barns use biomass briquettes or coal as their heat source. The combustion of these briquettes heats the air, which is then injected into the curing barn. Temperature is controlled by adjusting the fuel supply and fan speed. When the humidity inside the curing barn reaches a warning level, the fan speed is increased, increasing the air pressure and pushing open the damper at the exhaust vent, allowing the humid air at the bottom to escape and thus controlling the humidity within the curing barn.

[0003] Traditional tobacco curing chambers continuously discharge hot, humid air, causing a large amount of heat to escape directly into the air, resulting in resource waste and environmental pollution. Furthermore, it is difficult to precisely control the temperature at different heights in traditional tobacco curing chambers, leading to inconsistent tobacco quality in different areas of the chamber and affecting the economic value of the tobacco.

[0004] Based on this, the inventors conducted in-depth research on traditional baking ovens, modified the airflow circulation path in the ovens, and then designed a completely new airflow circulation system to solve the above problems. Utility Model Content

[0005] To overcome the above problems, the inventors conducted in-depth research and designed an airflow circulation system for a tobacco curing barn. This system includes a heating section and a dehumidification section. The heating section comprises a temperature control chamber, a mixing chamber, a diversion chamber, and a curing barn connected in sequence. The dehumidification section includes a dehumidification waste heat recovery chamber and an air intake chamber. Multiple parallel heat exchange pipes are installed inside the dehumidification waste heat recovery chamber. One end of each heat exchange pipe is connected to the air intake chamber, and the other end is connected to the outside atmosphere for dehumidification. The air intake chamber is connected to the bottom of the curing barn. The wet waste heat recovery chamber is equipped with an air inlet and an air outlet. The air inlet is connected to the outside atmosphere to introduce fresh air, and the air outlet is connected to the temperature control chamber. A fan is installed at the top of the temperature control chamber. The fan drives the gas in the temperature control chamber to enter the drying oven after passing through the mixing chamber and the diversion chamber. The gas then flows back to the temperature control chamber from the bottom of the drying oven, forming a continuous cycle. When the humidity in the drying oven is too high, the dehumidification section is opened to remove moisture and introduce fresh air from the outside. The air is then preheated in the dehumidification waste heat recovery chamber, thus completing this utility model.

[0006] Specifically, the purpose of this utility model is to provide an airflow circulation system for a tobacco curing chamber, which includes a heating section and a dehumidification section.

[0007] The heating section includes a temperature control chamber 1, a mixing chamber 2, a diversion chamber 3, and a drying room 4 connected in sequence;

[0008] A combustion furnace 11 is installed in the temperature control chamber 1, and the combustion furnace 11 is connected to a gas supply device 13 located outside the chamber via a pipe 12.

[0009] The dehumidification section includes a dehumidification waste heat recovery chamber 6 and an air intake chamber 7. Multiple parallel heat exchange pipes 8 are installed inside the dehumidification waste heat recovery chamber 6. One end of each heat exchange pipe 8 is connected to the air intake chamber 7, and the other end is connected to the outside atmosphere. The air intake chamber 7 is connected to the bottom of the drying room 4.

[0010] An air inlet 61 and an air outlet 62 are provided on the dehumidification and waste heat recovery chamber 6. The air inlet 61 is connected to the outside atmosphere, and the air outlet 62 is connected to the temperature control chamber 1.

[0011] The top of the temperature control chamber 1 is connected to the mixing chamber 2. A fan 5 is installed at the connection point. The fan 5 causes the gas in the temperature control chamber 1 to pass through the mixing chamber 2 and the diversion chamber 3 and then enter the drying chamber 4. The gas then flows back to the temperature control chamber 1 from the bottom of the drying chamber 4. The gas includes the gas stored in the heating section and also includes outside air that enters the temperature control chamber 1 through the air inlet 61, the dehumidification and waste heat recovery chamber 6 and the air outlet 62 in sequence.

[0012] In the temperature control chamber 1, a heat exchanger 14 and a backup electric heater 15 are provided above the combustion furnace 11. The gas after combustion in the combustion furnace 11 is discharged to the outside of the temperature control chamber 1 after passing through the heat exchanger 12. The heat generated by combustion in the combustion furnace 11 is diffused through the heat exchanger 14, thereby increasing the overall heating rate of the gas in the temperature control chamber 1.

[0013] The air outlet 62 is connected to the top of the temperature control chamber 1 and is located at a height close to the fan 5.

[0014] In the curing barn 4, tobacco leaves to be cured are hung.

[0015] The bottom of the drying chamber 4 is connected to both the temperature control chamber 1 and the air intake chamber 7; a dehumidification baffle door 71 that can be opened or closed is provided between the drying chamber 4 and the air intake chamber 7.

[0016] The diversion chamber 3 is connected to the mixing chamber 2 on one side, and has multiple heating ports arranged vertically on the other side that are connected to the drying chamber 4.

[0017] Furthermore, each heating port is equipped with an electrically controlled baffle gate 31. Multiple electrically controlled baffle gates 31 are independently controlled to control the opening or closing of the heating port, as well as the gas flow rate when it is open.

[0018] The heating port and the electrically controlled baffle door 31 control the position of hot air entering the drying chamber 4, so that the temperature at various height positions in the drying chamber 4 is basically the same.

[0019] The number of heating ports and electrically controlled baffle doors 31 is consistent with the number of tobacco leaf layers in the curing barn 4; that is, each layer of tobacco leaves corresponds to a set of heating ports and electrically controlled baffle doors 31.

[0020] Three or four heating ports are opened on the diversion chamber 3.

[0021] The heat exchange tubes 8 in the dehumidification and waste heat recovery chamber 6 are arranged in a reciprocating bend to ensure that the heat exchange tubes 8 are in full contact with the air flowing through the dehumidification and waste heat recovery chamber 8 and are fully preheated.

[0022] The heat exchange tube 8 has inwardly extending fins 81 on its inner wall.

[0023] The heat exchange tube 8 has an inner diameter of 5-8 cm, the fins 81 have a height of 0.8-1.2 cm, and 12-16 fins are provided on each heat exchange tube, with the fins evenly distributed on the inner wall of the heat exchange tube.

[0024] An air intake baffle door is provided at the air intake 61, and the air intake baffle door and the dehumidification baffle door 71 open or close synchronously.

[0025] The fan 5 includes a high-speed setting and a low-speed setting.

[0026] When the humidity of the gas in the drying room 4 does not reach the set value, the fan 5 starts at a low speed, and the exhaust damper door 71 and the air inlet damper door are both closed.

[0027] When the humidity of the gas in the drying chamber 4 reaches the set value, the fan 5 starts at a high speed and simultaneously opens the dehumidification baffle door 71 and the air inlet baffle door.

[0028] The beneficial effects of this utility model include:

[0029] (1) According to the airflow circulation system in the tobacco curing room provided by this utility model, the system is equipped with a dehumidification waste heat recovery chamber, which can use the humid air discharged during dehumidification to preheat the air entering the curing room, thereby reducing the discharge temperature of the dehumidified air and improving the heat utilization rate.

[0030] (2) According to the airflow circulation system in the tobacco curing chamber provided by this utility model, the heat exchange tube of the dehumidification waste heat recovery chamber is provided with fins, which can increase the contact area between the moisture and the heat exchange tube, increase the temperature of the heat exchange tube, and improve the heat exchange efficiency. The fin structure can also increase the liquefaction and condensation rate of water vapor in the humid air, thereby releasing more latent heat and further improving the utilization rate of heat.

[0031] (3) According to the airflow circulation system in the tobacco curing chamber provided by this utility model, multiple heating ports are arranged vertically in the diversion chamber, so as to control the input height of hot air and regulate the temperature of each height layer in the curing chamber, so that the temperature in all parts of the curing chamber is basically the same, ensuring the curing quality and curing efficiency of tobacco leaves. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the airflow circulation system in the tobacco curing chamber of this application;

[0033] Figure 2 This is a schematic diagram showing the external outline of the airflow circulation system in the tobacco curing chamber of this application;

[0034] Figure 3 This diagram shows the structure of the heat exchange tube connecting to the outside in the airflow circulation system of the tobacco curing chamber of this application.

[0035] Explanation of reference numerals in the attached figures

[0036] 1-Temperature Control Chamber

[0037] 11-Combustion Furnace

[0038] 12-pipeline

[0039] 13-Gas supply device

[0040] 14-Heat Exchanger

[0041] 15-Standby electric heater

[0042] 2-Mixing Chamber

[0043] 21-Inspection Port

[0044] 3-Diversion Chamber

[0045] 31-Electrically controlled baffle door

[0046] 4- Drying Room

[0047] 41-Observation Window

[0048] 5-fan

[0049] 6-Dehumidification and Waste Heat Recovery Chamber

[0050] 61-Air Inlet

[0051] 62-Air outlet

[0052] 71-Dehumidification baffle door

[0053] 7-Air Intake

[0054] 8-Heat exchanger tube

[0055] 81-fin Detailed Implementation

[0056] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present invention will become clearer and more apparent.

[0057] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0058] This utility model provides an airflow circulation system for a tobacco curing chamber, such as Figure 1 and Figure 2 As shown, the airflow circulation system includes a heating section and a dehumidification section. The heating section includes a temperature control chamber 1, a mixing chamber 2, a diversion chamber 3, and a drying room 4 connected in sequence.

[0059] The temperature-controlled chamber 1 is equipped with a combustion furnace 11, which is connected to an external gas supply device 13 via a pipe 12. The gas supply device 13 provides the combustion furnace 11 with a uniformly mixed clean energy fuel and combustion-supporting air in real time. The clean energy fuel is a gaseous fuel to facilitate thorough mixing with combustion-supporting air. Other fuels can be natural gas, alcohol, hydrogen, etc., or other vaporizable fuels primarily composed of hydrocarbons. The gas supply device 13 in this application can vaporize liquid fuel and then mix in excess combustion-supporting air to ensure complete combustion of the fuel, with the combustion products being carbon dioxide and / or water. Preferably, the fuel in this application is a water-hydrogen-hydrogen fuel.

[0060] The combustion furnace 11 is cylindrical and hollow inside to provide space for fuel combustion. The combustion furnace 11 has a certain height to provide sufficient space for the combustion of gaseous fuel, ensuring that the fuel can be fully burned as it flows upward to the top opening of the combustion furnace 11, turning into combustion product exhaust gas, which then enters the heat exchanger for full heat exchange, and is further discharged to the outside of the temperature control chamber after heat exchange.

[0061] The dehumidification section includes a dehumidification waste heat recovery chamber 6 and an air intake chamber 7. Multiple parallel heat exchange pipes 8 are installed inside the dehumidification waste heat recovery chamber 6. One end of each heat exchange pipe 8 is connected to the air intake chamber 7, and the other end is connected to the outside atmosphere. The air intake chamber 7 is connected to the bottom of the drying room 4.

[0062] An air inlet 61 and an air outlet 62 are provided on the dehumidification and waste heat recovery chamber 6. The air inlet 61 is connected to the outside atmosphere, and the air outlet 62 is connected to the temperature control chamber 1.

[0063] The top of the temperature-controlled chamber 1 is connected to the mixing chamber 2. A fan 5 is installed at the connection point. The fan 5 drives the gas in the temperature-controlled chamber 1 through the mixing chamber 2 and the diversion chamber 3 into the drying oven 4, and then back into the temperature-controlled chamber 1 from the bottom of the drying oven 4. The gas includes the gas stored in the heating section, as well as outside air that enters the temperature-controlled chamber 1 through the air inlet 61, the dehumidification and waste heat recovery chamber 6, and the air outlet 62 in sequence. In this application, heat transfer in the drying oven is mainly achieved through the flow of hot air, and the fan is the main driving force for the flow of hot air.

[0064] Because the air outlet 62 is close to the fan, the air entering the temperature control chamber 1 from the outside stays in the temperature control chamber 1 for a short time, and cannot be fully mixed and heated. This results in uneven gas temperature when passing through the fan, making it unsuitable for direct introduction into the drying room 4 for heating. Based on this, the mixing chamber 2 is provided in this application, which can extend the gas flow path, giving it more time and space for mixing and heat exchange. It can also promote relative flow and collision between various source gases by changing the flow direction, so as to achieve a fully balanced temperature.

[0065] Preferably, an inspection port 21 is also provided on the mixing chamber 2, so that maintenance personnel can enter the mixing chamber 2 to perform maintenance on components such as motors.

[0066] In this application, by setting up the aforementioned circulating heating section, the hot air in the drying chamber 4 can be recycled; that is, some of the gas circulates between the drying chamber 4 and the temperature control chamber 1, reducing the gas emission to the outside and improving the heat utilization rate.

[0067] In this application, the top of the temperature control chamber 1 is a sealed structure with a channel only opened at the fan. The fan is located directly above the temperature control chamber 1. This structure allows the hot air in the temperature control chamber to flow to the next chamber only through the fan. Moreover, with the hot air moving upwards on its own, resources can be saved to the greatest extent and energy consumption can be reduced.

[0068] In a preferred embodiment, a heat exchanger 14 and a backup electric heater 15 are provided above the combustion furnace 11 in the temperature control chamber 1. The heat generated by combustion in the combustion furnace 11 is diffused through the heat exchanger 14 to increase the overall heating rate of the gas in the temperature control chamber 1.

[0069] The heat exchanger 14 comprises multiple finned metal plates arranged side-by-side above the combustion furnace, with multiple metal pipes running through them for the exhaust gas generated by the combustion furnace 11 to flow through, thereby fully heating the heat exchanger 14. This allows the heat exchanger 14 to rapidly heat up under the action of the combustion furnace 11, and its large surface area ensures that the air in the temperature control chamber 1 comes into full contact with the heat exchanger 14, thus heating the air in the temperature control chamber 1. In this application, by using both the combustion furnace 11 and the heat exchanger 14 to heat the gas in the temperature control chamber 1, the gas in the temperature control chamber 1 can be heated more quickly, thus carrying more heat when entering the mixing chamber.

[0070] The backup electric heater 15 does not start under normal operation. It starts to provide heat in case of gas supply device 13 failure or fuel shortage, ensuring that the temperature in the curing barn 4 does not change suddenly due to the failure, and ensuring that the tobacco leaves in the curing barn can complete basic curing operations even under extreme conditions, thus avoiding losses for farmers.

[0071] In a preferred embodiment, the air outlet 62 is connected to the top of the interior of the temperature control chamber 1, located at a height close to the fan 5. This arrangement allows the suction force of the fan 5 to act more directly on the dehumidification and waste heat recovery chamber 6, thereby facilitating the extraction of outside air.

[0072] In a preferred embodiment, such as Figure 1 and Figure 2 As shown, tobacco leaves to be cured are hung in the curing barn 4. A horizontal hanging rod is installed in the curing barn 4 to hang strings of tobacco leaves for curing. Multiple sensors are installed on the hanging rod, which can measure temperature and humidity in real time. These sensors are connected to the overall control system of the curing barn to obtain real-time temperature and humidity conditions at various points within the curing barn, allowing for adjustments to the curing strategy based on the current curing stage and status.

[0073] Preferably, a heat insulation layer is laid on the wall surface of the baking oven 4 to reduce radiative heat loss and improve the utilization rate of thermal energy.

[0074] On the wall of the curing barn 4, observation windows 41 are provided on both sides of the temperature control chamber. The observation windows 41 are glass windows, through which the current state of the tobacco leaves in the curing barn, such as the degree of curling and color, can be observed from the outside, so as to adjust the curing parameters accordingly.

[0075] The bottom of the drying chamber 4 is connected to both the temperature control chamber 1 and the air intake chamber 7. A dehumidification baffle door 71 that can be opened or closed is provided between the drying chamber 4 and the air intake chamber 7. When the humidity in the drying chamber 4 is lower than the set threshold, the dehumidification baffle door 71 is closed and the dehumidification section temporarily stops working. When the humidity in the drying chamber 4 reaches the set threshold, the dehumidification baffle door 71 is opened and the dehumidification section starts working.

[0076] In a preferred embodiment, one side of the diversion chamber 3 is connected to the mixing chamber 2, and the other side has multiple heating ports arranged vertically and connected to the drying chamber 4.

[0077] Furthermore, each heating port is equipped with an electrically controlled baffle gate 31. Multiple electrically controlled baffle gates 31 are independently controlled to control the opening or closing of the heating port, as well as the gas flow rate when it is open.

[0078] In this application, during the actual baking process, at least one of the multiple electronically controlled baffle doors 31 is ensured to be in the open state to ensure that the airflow can be kept circulating and to avoid local high temperature.

[0079] In a preferred embodiment, the number of heating ports and electrically controlled baffle doors 31 is consistent with the number of tobacco leaf layers in the curing barn 4; that is, each layer of tobacco leaves corresponds to a set of heating ports and electrically controlled baffle doors 31.

[0080] Three or four heating ports are opened on the diversion chamber 3.

[0081] In a preferred embodiment, the heat exchange tubes 8 in the dehumidification and waste heat recovery chamber 6 are arranged in a reciprocating bend pattern to ensure sufficient contact between the heat exchange tubes 8 and the air flowing through the dehumidification and waste heat recovery chamber 8, thus achieving sufficient preheating. Preferably, a water storage tank is provided at the bottom of the air intake chamber 7 to collect condensate dripping from the heat exchange tubes.

[0082] The gas in the drying chamber 4 enters the heat exchange tube 8 through the exhaust channel 21 and is then discharged into the outside atmosphere. While passing through the heat exchange tube, the outside air entering the temperature control chamber 1 is preheated in the dehumidification and waste heat recovery chamber 6. That is, when the outside air enters the dehumidification and waste heat recovery chamber 6, it flows upward and enters the temperature control chamber 1 through the exhaust port 62, making full contact with the heat exchange tube 8, thereby increasing its temperature and achieving the preheating effect, realizing the recovery and utilization of heat in the humid air to be discharged.

[0083] In a preferred embodiment, when the dehumidification baffle door is closed, the connection between the air intake chamber and the heat exchange pipe 8 is cut off, and gas cannot enter or exit.

[0084] When the humidity of the gas in the drying chamber 4 reaches the set value, the dehumidification baffle door 71 is opened, so that the gas in the drying chamber 4 carrying moisture is discharged into the outside atmosphere through the heat exchange tube 8.

[0085] Preferably, an air intake baffle door is provided at the air intake 61, and the air intake baffle door and the dehumidification baffle door 71 open or close simultaneously; that is, dehumidification and air intake are carried out simultaneously. When dehumidification is not required, the baking chamber only introduces fuel and combustion air from the outside, and the main gas in the baking chamber achieves autonomous circulation, reducing the overflow of gas and thus reducing heat loss.

[0086] Preferably, such as Figure 3 As shown, inwardly extending fins 81 are provided on the inner wall of the heat exchange tube 8.

[0087] The inner diameter of the heat exchange tube 8 is 5-8cm, preferably 6cm, and the height of the fins is 0.8-1.2cm, preferably 0.9cm. Each heat exchange tube has 12-16 fins, preferably 14, and the fins are evenly distributed on the inner wall of the heat exchange tube.

[0088] The inventors have discovered that when the baking chamber is in the same dehumidification stage, the outlet temperature at the heat exchange tube is the lowest when the heat exchange tube and its fins are set to the above dimensions. That is, if only the number and size of the fins are changed, the outlet temperature at the heat exchange tube will also increase, resulting in a decrease in thermal energy utilization efficiency.

[0089] The present invention has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and serve only an illustrative purpose. Based on this, various substitutions and improvements can be made to the present invention, all of which fall within the protection scope of the present invention.

Claims

1. A system for circulating air in a tobacco curing barn, comprising: The air flow circulation system comprises a heating section and a dehumidification section, The heating section comprises a temperature control cabin (1), a mixing cabin (2), a distribution cabin (3) and a curing room (4) connected in sequence; A combustion furnace (11) is arranged in the temperature control cabin (1), and the combustion furnace (11) is communicated with a gas supply device (13) outside through a pipeline (12), The dehumidification section comprises a dehumidification waste heat recovery cabin (6) and an air inlet cabin (7), a plurality of parallel heat exchange pipes (8) are arranged in the dehumidification waste heat recovery cabin (6), one end of the heat exchange pipes (8) is communicated with the air inlet cabin (7), the other end is communicated with the outside atmosphere, and the air inlet cabin (7) is communicated with the bottom of the curing room (4); An air inlet (61) and an air outlet (62) are arranged on the dehumidification waste heat recovery cabin (6), the air inlet (61) is communicated with the outside atmosphere, and the air outlet (62) is communicated with the temperature control cabin (1); The top of the temperature control cabin (1) is communicated with the mixing cabin (2), a fan (5) is arranged at the communication position, the gas in the temperature control cabin (1) is forced to flow into the mixing cabin (2) and the distribution cabin (3) and then into the curing room (4) through the fan (5), and the gas flows back into the temperature control cabin (1) from the bottom of the curing room (4); the gas comprises the gas stored in the heating section, and also comprises the outside air which enters the temperature control cabin (1) through the air inlet (61), the dehumidification waste heat recovery cabin (6) and the air outlet (62) in sequence.

2. The air flow circulation system in the tobacco curing room according to claim 1, wherein A heat exchanger (14) and a backup electric heater (15) are arranged above the combustion furnace (11) in the temperature control cabin (1), the gas combusted in the combustion furnace (11) is discharged to the outside of the temperature control cabin (1) after passing through the heat exchanger (14), the heat exchanger (14) diffuses the heat generated by the combustion in the combustion furnace (11), and the overall temperature rising speed of the gas in the temperature control cabin (1) is improved.

3. The air flow circulation system in the tobacco curing room according to claim 1, wherein The air outlet (62) is communicated to the top end inside the temperature control cabin (1) and is located at a height position close to the fan (5).

4. The air flow circulation system in the tobacco curing room according to claim 1, wherein The tobacco to be cured is hung in the curing room (4); The bottom of the curing room (4) is communicated with the temperature control cabin (1) and the air inlet cabin (7), and a dehumidification baffle door (71) which can be opened or closed is arranged between the curing room (4) and the air inlet cabin (7).

5. The air flow circulation system in the tobacco curing room according to claim 1, wherein One side of the distribution cabin (3) is communicated with the mixing cabin (2), and the other side is provided with a plurality of heating ports arranged in an up-down manner and communicated with the curing room (4), An electric control baffle door (31) is arranged on each heating port, a plurality of electric control baffle doors (31) are independently controlled, the opening or closing of the heating port and the gas flow when the heating port is opened are controlled through the electric control baffle door (31). The hot air is controlled to be inhaled at a position in the curing barn (4) by the heat supply ports and the electrically controlled baffle doors (31), so that the temperature at each height position in the curing barn (4) is substantially uniform.

6. The air circulation system in a tobacco curing barn according to claim 5, wherein the number of the heat supply ports and the electrically controlled baffle doors (31) is consistent with the number of tobacco layers in the curing barn (4), i.e. each layer of tobacco corresponds to a set of heat supply ports and electrically controlled baffle doors (31). Three or four heat supply ports are arranged on the shunt cabin (3).

7. The air circulation system in a tobacco curing barn according to claim 1, wherein the heat exchange pipes (8) in the waste heat recovery cabin (6) are arranged in a reciprocating bending manner so that the heat exchange pipes (8) are in full contact with the air flowing through the waste heat recovery cabin (6) and are fully preheated.

8. The air circulation system in a tobacco curing barn according to claim 7, wherein the inner wall of the heat exchange pipes (8) is provided with inwardly extending fins (81).

9. The air circulation system in a tobacco curing barn according to claim 8, wherein the inner diameter of the heat exchange pipes (8) is 5-8 cm, the height of the fins (81) is 0.8-1.2 cm, 12-16 fins are arranged on each heat exchange pipe, and the fins are uniformly distributed on the inner wall of the heat exchange pipes.

10. The air circulation system in a tobacco curing barn according to claim 1, wherein an air inlet baffle door is arranged at the air inlet (61), and the air inlet baffle door is synchronously opened or closed with the exhaust baffle door (71); the fan (5) includes a high speed gear and a low speed gear, when the humidity of the gas in the curing barn (4) does not reach the set value, the fan (5) starts at a low speed gear, and the exhaust baffle door (71) and the air inlet baffle door are both in a closed state; when the humidity of the gas in the curing barn (4) reaches the set value, the fan (5) starts at a high speed gear, and the exhaust baffle door (71) and the air inlet baffle door are synchronously opened. ​ ​ ​ ​ ​

Images