A negative pressure moisture removal and heat exchange tobacco curing barn heating system and a curing barn

Abstract

This invention discloses a negative pressure dehumidification and heat exchange heating system for tobacco curing barns and the curing barn itself. The tobacco curing barn heating system includes a fan, an internal / external circulation switching device, and a waste heat recovery heat exchanger. The fan is located in the lower part of the heating chamber of the curing barn, immediately above the return air vent. The internal / external circulation switching device is located above the fan and is used to switch between a fully internal circulation state, a simultaneous internal / external circulation state, and a fully external circulation state. The fan is positioned between the return air vent and the heater, preventing the fan from directly absorbing heat from the heater at close range, thus avoiding the threat of high temperatures and damage to the fan. Through these settings, the system achieves orderly switching between a fully external circulation state within the curing barn. When the system requires dehumidification, a negative pressure effect is generated in the tobacco layer (material chamber), allowing moisture from the tobacco leaves to flow smoothly out and be quickly discharged from the curing barn. This enhances the overall dehumidification efficiency of the curing barn, promotes improved curing quality, reduces heat loss, and minimizes the risk of fan damage.

Description

Technical Field

[0001] This invention relates to the technical field of tobacco curing barn dehumidification and heat exchange systems, specifically to a negative pressure dehumidification and heat exchange system for tobacco curing barns and the curing barn itself. Background Technology

[0002] Intensive curing barns are an important infrastructure for tobacco production, playing a vital role in promoting appropriately scaled planting, improving tobacco efficiency, and saving energy and reducing costs. They are of great practical significance to the development of modern tobacco agriculture.

[0003] When the material room and heating room of a drying or baking room are in normal use, there will be air flowing inside. This internal flow is called internal circulation. After running for a long time, due to poor moisture, oxygen, stale air and air cleanliness inside, it is necessary to exchange air with the outside. This exchange is called external circulation.

[0004] With the widespread adoption of tobacco clamps and the increased loading density, various problems have become increasingly apparent. For example, the fan power is clearly insufficient, the tobacco curing time is prolonged, and the dried tobacco generally has a characteristic fuel odor. Upon investigation, we found that the currently used intensive tobacco curing barns and fruit and vegetable dryers use fans to blow hot air into the barn. The pressure generated relative to the tobacco leaves is positive, while the pressure relative to the heating equipment is negative. This results in: 1. Dirt inside the tobacco leaves is difficult to escape; 2. The efficiency of removing hot and humid air from the barn is low; 3. The fans are placed directly above the heaters and constantly draw heat from them, making them susceptible to damage from high-temperature stress.

[0005] Therefore, there is a need for a curing barn heating system that can improve the efficiency of tobacco leaf dehumidification, reduce heat loss, and reduce the threat of damage to the fan. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a negative pressure dehumidification and heat exchange heating system for tobacco curing barns and a curing barn itself. The fan is placed at the return air vent of the curing barn, keeping it away from the heater to avoid the threat and damage from high temperatures. Simultaneously, an internal and external circulation switching device enables the curing barn to switch states, and a waste heat recovery heat exchanger recovers the heat hidden in the dehumidified air to preheat the fresh air. Through this invention, the goals of improving tobacco dehumidification efficiency, promoting tobacco curing quality, reducing heat loss, and minimizing the threat of fan damage are achieved.

[0007] Specifically, the present invention is implemented as follows:

[0008] A negative pressure dehumidification and heat exchange heating system for tobacco curing barns includes:

[0009] The fan is located in the lower part of the heating chamber of the drying room, right above the return air vent;

[0010] An internal and external circulation switching device is located above the fan and is used to switch the drying oven between a fully internal circulation state, a simultaneous internal and external circulation state, and a fully external circulation state. In the fully internal circulation state, the circulating air is sent into the heating chamber by the fan through the circulation channel and then into the material chamber. In the fully external circulation state, the hot and humid air from the material chamber is discharged from the drying oven by the fan through the dehumidification channel. In the combined circulation and dehumidification state, part of the air from the material chamber is sent into the heating chamber through the circulation channel, and the other part is discharged from the drying oven through the dehumidification channel.

[0011] A waste heat recovery heat exchanger is installed in the dehumidification channel. The waste heat recovery heat exchanger includes: an old air side, a fresh air side, an old air exhaust port, and a fresh air outlet. The fresh air outlet is connected to the circulation channel in the hot air chamber, and the fresh air inlet is connected to the air inlet of the drying room. An air inlet door is provided at the fresh air inlet. The inlet on the old air side is connected to the dehumidification channel, and the old air exhaust port is connected to the dehumidification port of the drying room.

[0012] In the fully external circulation state, the hot and humid air in the material chamber is discharged from the drying oven by the fan through the waste heat recovery heat exchanger. At the same time, the fresh air in the air inlet is preheated by the waste heat recovery heat exchanger and enters the circulation channel in the hot air chamber. While the hot and humid air in the material chamber is discharged to the outside through the waste heat recovery heat exchanger, the fresh air entering the drying oven is preheated.

[0013] Furthermore, the internal / external circulation switching device includes:

[0014] An internal and external circulation conversion door is located at the intersection of the circulation channel inlet and the dehumidification channel inlet, and the internal and external circulation conversion door is configured to be rotatable. When the internal and external circulation conversion door closes the dehumidification channel inlet, the drying oven is in a completely internal circulation state; when the internal and external circulation conversion door closes the circulation channel inlet, the drying oven is in a completely external circulation state; when the internal and external circulation conversion door is between the dehumidification channel and the circulation channel, the drying oven is in a state where internal and external circulation coexist.

[0015] Furthermore, the air inlet door is configured to open towards the fresh air inlet side of the waste heat recovery heat exchanger.

[0016] Furthermore, when the drying room is in a state of simultaneous internal and external circulation or a state of complete external circulation, a negative pressure is formed in the material chamber and the heating chamber of the drying room. The air inlet door will be sucked open under the action of negative pressure, and fresh air from the outside will be sucked towards the fresh air inlet of the waste heat recovery heat exchanger. Under the action of negative pressure, it will enter the heating chamber through the fresh air side of the waste heat recovery heat exchanger.

[0017] Furthermore, the heating room is equipped with a baffle, the upper part of which is a circulation channel and the lower part is a dehumidification channel. The heater is placed in the circulation channel, and the internal and external circulation conversion door is located at the entrance of the circulation channel.

[0018] Furthermore, an inlet channel is provided above the fan, and the internal and external circulation conversion door rotates within the inlet channel to switch the airflow direction, so as to realize the conversion between the complete internal circulation state, the complete external circulation state, and the simultaneous internal and external circulation state of the drying room.

[0019] Furthermore, a heater is installed within the circulation channel.

[0020] Furthermore, the waste heat recovery heat exchanger is a gas-to-gas heat exchanger.

[0021] The present invention also provides a curing barn, comprising: a heating chamber and a material chamber, wherein the upper part of the heating chamber is provided with an air outlet connected to the material chamber, and the lower part of the heating chamber is provided with an air inlet and a return air outlet connected to the material chamber; it also includes a tobacco curing barn heating system with negative pressure dehumidification and heat exchange as described above; the fan is located at the return air outlet.

[0022] Furthermore, a vent is provided on the side of the heating chamber away from the material chamber, and the vent is located at the outlet of the venting channel.

[0023] Working principle:

[0024] When the drying room is in full internal circulation mode, the internal and external circulation switching door closes the inlet of the dehumidification channel. At this time, the air from the material chamber is sent into the circulation channel by the fan, and then heated by the heater before being sent into the material chamber, thus realizing the circulation of hot air in the drying room.

[0025] When the humidity inside the drying oven is high, the internal and external circulation switching door rotates a certain angle towards the circulation channel. At this time, the drying oven enters a state of internal and external circulation simultaneously. Both the circulation channel and the dehumidification channel are partially open or partially closed. Part of the air in the material chamber circulates through the circulation channel, and the other part passes through the dehumidification channel, passes through the waste heat recovery heat exchanger, and is discharged from the dehumidification port. After this part of the air is discharged, it will reduce the air pressure in the circulation duct, heating chamber, and drying oven, creating a negative pressure in these areas. This negative pressure will act along the fresh air side of the waste heat recovery heat exchanger, and the suction force formed by the negative pressure will act on the air inlet door connected to the outside, causing the air inlet door to be sucked open. Then, the fresh air from the outside will enter the hot air chamber with the suction force and participate in the hot air exchange and circulation of the drying oven.

[0026] Meanwhile, after the internal and external circulation is activated, if the humidity in the drying chamber does not decrease within a certain period of time, the internal and external circulation switching door will be rotated further to close the circulation channel entrance. At this time, the drying chamber will gradually enter a deeper state of complete external circulation. When the complete external circulation is reached, all the hot and humid air from the material chamber will be discharged through the exhaust channel. At this time, the air inlet door will open to its maximum under negative pressure, and the amount of fresh air entering will also reach its maximum. The fresh air entering through the waste heat recovery heat exchanger will exchange heat with the exhaust air on the outlet side, raising the temperature of the fresh air on the inlet side while lowering the temperature of the exhaust air on the outlet side, thereby achieving the purpose of waste heat recovery.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) The present invention utilizes an internal and external circulation conversion device to reasonably control the circulation channel and the dehumidification channel, so that the material chamber, heating chamber and main channel of the curing barn generate a negative pressure environment without dead corners after the curing barn enters the dehumidification, thereby applying negative pressure to the tobacco leaves during curing and the heating chamber, causing the moisture inside the tobacco leaves to overflow and be quickly discharged from the curing barn, thus improving the dehumidification efficiency and curing quality of the tobacco leaves.

[0029] (2) The present invention places the fan at the front end of the heater. In the dehumidification and external circulation state, it can draw the smoke layer in the drying room and the heater in the hot air chamber to achieve the effect of negative pressure, thereby realizing the automatic opening and closing of the fresh air inlet door; at the same time, the front-mounted fan can be far away from the heater, protecting the fan motor from the influence of high temperature.

[0030] (3) The fresh air and the exhaust air exchange heat through the gas-to-gas heat exchanger of the waste heat recovery heat exchanger, so that the fresh air entering the hot air chamber circulation duct is preheated, the heat carried away by the exhaust is recovered, the heat loss is reduced, and the efficient utilization of heat energy is achieved. Attached Figure Description

[0031] Figure 1 A schematic diagram of the state of the drying room in Example 1 when it is in a fully internal circulation state;

[0032] Figure 2 A schematic diagram of the state of the drying room in Example 1 when it is in a state of simultaneous internal and external circulation;

[0033] Figure 3 A schematic diagram of the state of the drying room in Example 1 when it is in a fully external circulation state.

[0034] Figure label:

[0035] 1-Heating chamber; 11-Baffle; 12-Exhaust vent; 2-Material chamber; 21-Air outlet; 22-Return air vent; 3-Heater; 4-Fan; 5-Internal and external circulation conversion door; 6-Waste heat recovery heat exchanger; 7-Air inlet door. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0037] In this invention, a completely external circulation state means that there is only external circulation and no internal circulation; a completely internal circulation state means that there is only internal circulation and no external circulation; at the same time, the internal and external circulation states mean that internal and external circulations coexist, and the ratio of internal and external circulations can be adjusted. For example, when the external circulation accounts for 70%, the internal circulation is 30%; when the external circulation accounts for 55%, the internal circulation is 45%; when both are equal, they each account for 50%.

[0038] Example 1

[0039] like Figure 1-3 As shown, this embodiment provides a curing barn for curing tobacco leaves, comprising a heating chamber 1 and a material chamber 2. The heating chamber 1 and the material chamber 2 are connected by an upper air outlet 21 and a lower air return outlet 22. Airflow flows into the material chamber 2 from the upper air outlet 21 and flows out of the material chamber 2 from the air return outlet 22, forming a downward airflow curing barn. Conversely, an upward airflow curing barn is formed, which will not be described in detail here.

[0040] The heating chamber 1 has a built-in negative pressure dehumidification tobacco curing barn heating system, which includes: a heater 3, a fan 4, an internal and external circulation conversion device, and a waste heat recovery heat exchanger 6. The heater 3 is located inside the heating chamber 1, and the fan 4 is located at the bottom of the heating chamber 1 and above the return air inlet 22. A baffle 11 is installed between the fan 4 and the heater 3 to divide the space between them into a circulation channel and a dehumidification channel. A closing baffle is installed on the upper part of the fan 4 to form a closing channel. The left side of the closing channel is the entrance to the circulation channel, and the right side is the entrance to the dehumidification channel. The pivot point of the internal and external circulation conversion door 5 is connected to one end of the baffle 11. The door panel size of the internal and external circulation conversion door 5 should be larger than the cross-section of the circulation channel entrance and the dehumidification channel entrance. The internal and external circulation conversion door 5 can be manually adjusted and locked, or it can be driven by a common motor, a stepper motor, or other programmable motors to rotate. No limitation is made here.

[0041] The waste heat recovery heat exchanger 6 is a gas-to-gas heat exchanger located at the end of the dehumidification channel. The gas-to-gas heat exchanger includes: an old air side, a fresh air side, an old air exhaust port, and a fresh air outlet. The old air side inlet is located on the fan side, and the exhaust port is located on the drying chamber dehumidification port side. The heating chamber 1 is equipped with a dehumidification port, which is connected to the exhaust port of the waste heat recovery heat exchanger 6. Air from the fan 4 enters the old air side inlet of the waste heat recovery heat exchanger 6 through the dehumidification channel and exits through the exhaust port, ultimately exiting the drying chamber through the exhaust port. The fresh air side inlet is located at the bottom and connects to the drying chamber inlet, while the outlet is located at the top and connects to the hot air chamber. Outside fresh air enters the waste heat recovery heat exchanger 6 from the fresh air side and enters the hot air chamber from the outlet, participating in the circulation and exchange within the drying chamber.

[0042] An air inlet door 7 is installed at the air inlet of the curing barn. The air inlet door 7 is hinged to the bottom of the heating chamber 1 and is larger than the air inlet size. It is made of lightweight material, such as aluminum sheet, and is hung vertically at the air inlet by gravity. This means that the air inlet door 7 can only be opened by rotating upwards due to the negative pressure suction generated inside the curing barn. When there is no need for dehumidification in the curing barn, the air inlet door 7 is closed by its own weight. Only when there is a need for dehumidification in the curing barn, and when the internal and external circulation conversion door 5 operates to generate negative pressure inside the curing barn, will the door automatically open under the suction of the negative pressure. As the negative pressure gradually weakens or disappears, the door will close slightly or completely. Additionally, before officially starting the curing process after the tobacco leaves have been loaded, the degree of opening and closing of the door can be observed to check or judge whether the amount of tobacco leaves loaded is too large, and thus infer whether curing can continue. Specifically: when the amount of tobacco leaves harvested is large and all of them need to be loaded into the curing barn, after the tobacco leaves are loaded, the tobacco farmer can lower the target humidity to a sufficiently low level, so that the curing barn enters a state of simultaneous internal and external circulation. At this time, simply observe the degree of opening of the negative pressure self-opening air inlet door. If it opens easily and at a large opening angle, it indicates that the dehumidification response and power are strong, and there is no need to worry about the dehumidification not being able to be removed during curing. Conversely, if it opens very slowly and at a small opening angle, it indicates that the dehumidification response and power are weak. In this case, attention should be paid. First, check whether the amount of tobacco leaves loaded exceeds the limit. If the loading amount is normal, check whether there is a problem with the fan, etc. Otherwise, curing should not be started easily.

[0043] When the drying room is in full internal circulation mode, the internal and external circulation conversion door 5 closes the inlet of the dehumidification channel. At this time, the air from the material chamber 2 is sent into the circulation channel by the fan 4, and then heated by the heater 3 before being sent into the material chamber 2, thereby realizing the circulation of hot air in the drying room.

[0044] When the humidity inside the drying oven is too high, the internal and external circulation switching door 5 rotates at a certain angle to the circulation channel. At this time, the drying oven enters a state of simultaneous internal and external circulation. Both the circulation channel and the dehumidification channel are partially opened. Part of the air in the material chamber 2 circulates through the circulation channel, and the other part enters the dehumidification channel. After passing through the waste heat recovery heat exchanger 6, it is discharged from the dehumidification port. After this part of the air is discharged, the air pressure inside the drying oven will decrease, thus forming a negative pressure. That is, a negative pressure appears at the fresh air end of the waste heat recovery heat exchanger 6. The negative pressure state will partially draw open the air inlet door 7 of the drying oven air inlet. Fresh air enters the hot air chamber through the waste heat recovery heat exchanger 6 and participates in the circulation and exchange of hot air in the drying oven.

[0045] Meanwhile, under the internal and external circulation state, if the humidity in the drying room does not decrease within a certain period of time, the internal and external circulation conversion door 5 is further rotated to close the circulation channel inlet. At this time, the drying room enters a completely external circulation state, and all the air from the material chamber is discharged through the dehumidification channel. At this time, the air inlet door 7 is further opened under the negative pressure until it reaches the maximum opening. The fresh air passes through the waste heat recovery heat exchanger 6 and, according to the working principle of the air-to-air heat exchanger, performs non-contact heat exchange with the dehumidification air before entering the hot air chamber to participate in the circulation and exchange of hot air in the drying room.

[0046] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A tobacco curing barn heating system for negative pressure dehumidification and heat exchange, characterized in that, include: The fan (4) is located at the lower part of the heating chamber (1) of the drying room, right above the return air inlet; An internal and external circulation switching device is located above the fan (4) and is used to switch between the fully internal circulation state, the simultaneous internal and external circulation state, and the fully external circulation state of the drying room. In the fully internal circulation state, the air coming out of the fan (4) is sent into the heating chamber (1) through the circulation channel and enters the material chamber (2) from the heating chamber (1). In the fully external circulation state, the humid air from the material chamber (2) is discharged from the drying room by the fan (4) through the dehumidification channel. In the simultaneous internal and external circulation state, part of the air from the material chamber (2) is sent into the heating chamber (1) through the circulation channel, and the other part is discharged from the drying room through the dehumidification channel. Waste heat recovery heat exchanger (6) is located in the dehumidification channel. The waste heat recovery heat exchanger (6) includes: old air side, fresh air side, old air exhaust port and fresh air outlet. The fresh air outlet is connected to the circulation channel in the hot air chamber. The fresh air inlet is connected to the air inlet of the drying room. An air inlet door (7) is provided at the air inlet of the drying room. The inlet of the old air side is connected to the dehumidification channel. The old air exhaust port is connected to the dehumidification port of the drying room. In the fully external circulation state, the humid air in the material chamber (2) is discharged from the baking room by the fan (4) through the waste heat recovery heat exchanger (6), and at the same time, the fresh air in the air inlet enters the circulation channel in the hot air chamber through the waste heat recovery heat exchanger (6). The humid and hot air in the material chamber (2) preheats the fresh air drawn in from the outside through the waste heat recovery heat exchanger (6).

2. The tobacco curing barn heating system of claim 1, wherein, The internal and external circulation switching device includes: An internal and external circulation conversion door (5) is located at the intersection of the circulation channel inlet and the dehumidification channel inlet, and the internal and external circulation conversion door (5) is configured to be rotatable. When the internal and external circulation conversion door (5) closes the dehumidification channel inlet, the drying room is in a completely internal circulation state; when the internal and external circulation conversion door (5) closes the circulation channel inlet, the drying room is in a completely external circulation state.

3. The negative pressure dehumidification and heat exchange heating system for tobacco curing barns as described in claim 1, characterized in that, The air inlet door (7) is configured to open toward the waste heat recovery heat exchanger (6).

4. The negative pressure dehumidification and heat exchange heating system for tobacco curing barns as described in claim 3, characterized in that, When the drying room is in a state of simultaneous internal and external circulation or a state of complete external circulation, a negative pressure is formed in the material chamber and the heating chamber of the drying room. The air inlet door (7) will be sucked open under the action of negative pressure, and the outside fresh air will be sucked to the fresh air inlet of the waste heat recovery heat exchanger (6), and then enter the heating chamber through the fresh air side of the waste heat recovery heat exchanger (6) under the action of negative pressure.

5. The negative pressure dehumidification and heat exchange heating system for tobacco curing barns as described in claim 2, characterized in that, The heating room is equipped with a baffle (11), the upper part of which is a circulation channel and the lower part is a dehumidification channel. The heater (3) is placed in the circulation channel, and the inner and outer circulation conversion door (5) is located at the entrance of the circulation channel.

6. The negative pressure dehumidification and heat exchange heating system for tobacco curing barns as described in claim 2 or 5, characterized in that, An inlet channel is provided above the fan (4), and the internal and external circulation conversion door (5) rotates in the inlet channel to switch the air direction, so as to realize the conversion between the complete internal circulation state of the drying room, the internal and external circulation state and the complete external circulation state.

7. The negative pressure dehumidification and heat exchange heating system for tobacco curing barns as described in claim 2, characterized in that, A heater (3) is installed at the outlet end of the circulation channel.

8. The negative pressure dehumidification and heat exchange heating system for tobacco curing barns as described in claim 1, characterized in that, The waste heat recovery heat exchanger (6) is a gas-to-gas heat exchanger.

9. A drying room, comprising: The heating chamber (1) is provided with an air outlet (21) connected to the material chamber at the upper part, and an air inlet and a return air outlet (22) connected to the material chamber (2) at the lower part; characterized in that it further includes a tobacco curing barn heating system with negative pressure dehumidification and heat exchange as described in any one of claims 1-6; the fan (4) is located at the return air outlet (22).

10. The drying room as described in claim 9, characterized in that, The heating chamber is provided with a vent on the side away from the material chamber (1), and the vent is located at the outlet of the venting channel.

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