Tobacco drying rack with flow guide pipe and method for baking flue-cured tobacco with flow guide pipe

Abstract

The invention discloses a tobacco drying rack with a guide tube and a method for baking tobacco with a guide tube, which belongs to the field of tobacco-curing equipment and tobacco-curing technology, and solves the problem that there is a lack of a method for baking tobacco with a guide tube in the prior art, which shortens the baking time of a large box, improves the baking efficiency, saves costs, and has strong replicability. It mainly includes a frame, a crossbeam, an elevated frame and a low frame are provided on the frame, a groove is opened on the crossbeam, a tobacco rod is placed on the groove, a hook I is provided on the elevated frame and the low frame, a guide tube is provided on the hook I, a hook II is provided on the guide tube, and the guide tube is hung on the hook I through the hook II; the guide tube is provided with a round hole; the method for baking tobacco with a guide tube includes tobacco leaf harvesting and sorting, tobacco loading, and tobacco leaf baking, and the tobacco leaf yellowing stage, the tobacco leaf color fixing stage, the tobacco leaf dry tendon stage, and the tobacco leaf moisture regeneration stage are controlled by controlling fire and wind during tobacco leaf baking. The invention is mainly used to improve the quality of flue-cured tobacco and reduce the cost of flue-cured tobacco.

Description

Technical Field

[0001] The invention relates to tobacco-curing equipment and a tobacco-curing process, and in particular to a tobacco-curing rack with a flow guide pipe and a tobacco-curing method using the flow guide pipe. Background Art

[0002] Tobacco box baking refers to the use of special tobacco loading equipment to place tobacco leaves in a box-type tobacco basket for baking, completing the process of yellowing, coloring, and drying the tobacco leaves. Box baking can effectively solve the problems caused by small tobacco loading, excessive wind speed, and insufficient conversion of the internal chemical components of tobacco leaves. After baking, the leaf structure becomes loose, the oil content increases, the color is enhanced, and the aroma quality, aroma volume and concentration are greatly improved. However, due to the high density of tobacco loading and the large temperature difference between the layers of the tobacco box, the tobacco leaves in the box are heated and dissipated unevenly, and the yellowing and water loss of tobacco leaves at different positions in the box are inconsistent. In particular, the temperature in the middle of the tobacco basket is low, and the dry matter loss in the leaves is large. The tobacco leaves are thinner or the tobacco is bad after baking. The dry matter loss in the leaves is large, affecting the quality of tobacco leaves.

[0003] The current hanging pole flue-cured tobacco has a small output, high labor cost and low efficiency, while large box baking has solved the problem of output. Although there is an improvement in quality, it also brings the problem of high cost. Uneven temperature distribution in the tobacco box is the main problem that affects the time of large box baking. Effectively solving this problem will greatly reduce costs.

[0004] At present, there is a lack of a tobacco drying rack with a guide tube that is simple in structure, easy to use, uses a guide tube to assist the baking process, shortens the baking time in a large box, improves the baking efficiency, and saves costs, as well as a method for baking tobacco with a guide tube that can shorten the baking time in a large box, improve the baking efficiency, save costs, is easy to operate, and has strong replicability. Summary of the invention

[0005] The purpose of the present invention is to provide a tobacco drying rack with a guide tube and a method for baking flue-cured tobacco with a guide tube, so as to solve the problem in the prior art that there is a lack of a tobacco drying rack with a guide tube that uses a guide tube to assist the baking process, shortens the baking time in a large box, improves the baking efficiency, and saves costs, as well as a method for baking flue-cured tobacco with a guide tube that can shorten the baking time in a large box, improve the baking efficiency, save costs, is easy to operate, and has strong replicability.

[0006] The present invention is achieved through the following technical solutions:

[0007] A tobacco drying rack with a guide tube comprises a frame body, a crossbeam, an elevated frame and a low frame are arranged on the frame body, a groove is formed on the crossbeam, tobacco rods are placed on the groove, a hook I is arranged on the elevated frame and the low frame, a guide tube is arranged on the hook I, a hook II is arranged on the guide tube, and the guide tube is hung on the hook I through the hook II; a round hole is arranged on the guide tube.

[0008] Furthermore, a fixing seat is provided at one end of the tobacco rod, and a mounting cap is provided at the other end of the tobacco rod. The tobacco rod is suspended in a groove on the beam through the fixing seat and the mounting cap; and a pointed tip is provided at the front end of the tobacco rod.

[0009] Furthermore, the circular holes on the flow guide pipe are arranged in a spiral pattern.

[0010] Furthermore, the high frame and the low frame are provided with air inlets.

[0011] Furthermore, a limiting rack is provided above the groove 6 and below the fixing seat 5 and the mounting cap 11 .

[0012] A flue-cured tobacco guide tube baking method comprises the following steps: tobacco leaf harvesting, sorting and tobacco loading, tobacco leaf baking, during tobacco leaf baking, fire and wind are controlled to achieve control of tobacco leaf yellowing stage, tobacco leaf color fixing stage, tobacco leaf dry tendon stage and tobacco leaf moisture recovery stage, and during tobacco leaf sorting and tobacco loading, the variety, nutritional level, position and maturity of fresh tobacco leaves in the same baking room are consistent.

[0013] Furthermore, the tobacco leaves harvested, sorted and packed are selected from the lower tobacco leaves 7-14 days after topping, when the leaves are mainly yellow-green, with 50-60% of the leaf surface yellow-green, and more than 1 / 3 of the main veins are whitened; the middle leaves are harvested 21-35 days after topping, when the leaves are mostly yellow and less green, with 70-80% of the leaf surface yellow-green, and more than 2 / 3 of the main veins are whitened; the upper leaves are harvested 56-63 days after topping, when the leaves are mainly yellow, with 90-100% of the leaf surface yellow-green, and the main veins are basically completely white; 3-4 leaves are harvested from each plant each time, and harvesting is done every 6-7 days, and the maturity of the tobacco leaves harvested increases with the position. After the lower part is harvested, wait 5-7 days before harvesting the middle part. After the middle part is harvested, wait 7-10 days before harvesting the upper part. The 6 left and right leaves of the upper part are harvested at one time after they are fully mature. The harvesting is completed in 4-5 times. When loading tobacco, the lower leaves ≥4500kg / furnace, the middle leaves ≥5000kg / furnace, and the upper leaves ≥5500kg / furnace. Each baking room has 10 tobacco boxes for each baking. The lower tobacco box is 450-500kg, the middle tobacco is 500-550kg, and the upper tobacco is 550-600kg. Use tobacco drying racks with guide pipes to achieve uniform ventilation during baking and blow through the tobacco leaves.

[0014] Furthermore, in the yellowing stage of tobacco leaves, the dry-bulb temperature is raised to 38°C at a rate of 1°C / h, the wet-bulb temperature is maintained at 37°C-38°C, and the temperature is stabilized. After the tobacco leaves turn yellow by about 50%-60%, the dry-bulb temperature is raised to 40°C at a rate of 0.5°C-1°C / h, the wet-bulb temperature is controlled at 37°C-38°C, and the temperature is stabilized so that the tobacco leaves sweat and become soft. When the tobacco leaves turn yellow by 80%, the dry-bulb temperature is raised to 42°C at a rate of 0.5°C-1°C / h, the wet-bulb temperature is maintained at 36.5°C-37.5°C, and the temperature is stabilized for a longer time so that the tobacco leaves continue to turn yellow and lose water, and then enter the color fixing stage; in this stage, the yellowing degree of the lower tobacco leaves reaches 80%-90%, and the yellowing degree of the middle and upper tobacco leaves reaches 90%-100%, the yellow leaves of the tobacco leaves have blue veins and wither, and the main veins become soft and broken but not broken.

[0015] Furthermore, in the tobacco leaf color fixing stage, the dry-bulb temperature is raised to 45°C at a rate of 0.5°C / h, the wet-bulb temperature is maintained at 37°C-38°C, and the temperature is stabilized so that the tobacco leaf tips are curled; the dry-bulb temperature is then raised to 47°C-48°C at a rate of 0.5°C-1°C / h, the wet-bulb temperature is controlled at 37°C-38°C, and the temperature is stabilized so that the tobacco leaves reach the small roll with yellow tendons and yellow leaves; the dry-bulb temperature is further raised to 50°C at a rate of 1°C / h, the wet-bulb temperature is controlled at 37.5°C-38.5°C, and the temperature is stabilized so that the tobacco leaves approach the large roll; then the dry-bulb temperature is raised to 54°C at a rate of 1°C / h, the wet-bulb temperature is controlled at 38.5°C-39.5°C, and the temperature is stabilized so that the tobacco leaves are rolled into large rolls, and then the dry-bulb stage is entered; in this stage, the tobacco leaves have yellow tendons and yellow leaves, and the leaves are completely dry.

[0016] Furthermore, in the tobacco leaf drying stage, the dry-bulb temperature is raised to 65°C-68°C at a rate of 1°C / h, the tobacco clamping temperature is raised by 1°C-2°C and kept stable, and the wet-bulb temperature is controlled at 40°C-43°C until the main veins of all tobacco leaves in the room are completely dried; if the main veins of the tobacco leaves dry too slowly in the middle and late stages of drying, the dry-bulb temperature is manually adjusted to control the dry-bulb temperature at 65°C-68°C and the wet-bulb temperature at 40°C-43°C, and the air inlet door is opened and closed intermittently to make the wet-bulb temperature in the drying room fluctuate repeatedly within the range of 40°C-43°C, and the wet-bulb temperature is high for a short time, that is, reaching 45°C, so that the dry-bulb temperature exceeds 68°C for a short time to accelerate the diffusion of moisture in the tobacco leaves and promote the drying of the tobacco leaves.

[0017] Furthermore, in the tobacco leaf rehumidification stage, when the relative humidity of the outside air is high, after confirming that all the tobacco leaves in the room are completely dry, stop heating, turn off the fan power supply, and when the temperature of the curing room drops to 40°C ~ 45°C, open the smoke loading door, cold air inlet and dehumidification port to allow the tobacco leaves to absorb moisture naturally and have an appropriate moisture content; when the relative humidity of the outside air is low, when the temperature of the curing room drops to 40°C ~ 45°C, evenly sprinkle water on the floors of the smoke loading room and the heating room, then close the doors and windows of the curing room and the air inlet, turn on the fan for ventilation, and use the generated steam to increase the humidity of the circulating air to rehumidify the tobacco leaves. If the heating equipment has cooled down during rehumidification, it will be heated again, and the temperature will be controlled at 40°C ~ 45°C to promote the vaporization of moisture so that the moisture content of the tobacco leaves is appropriate.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The tobacco drying rack with a guide tube has a simple structure and is easy to use. It solves the problem of uneven heating of tobacco leaves during baking in a large box, which leads to inconsistent yellowing and water loss of tobacco leaves at different positions in the box. The guide tube is used to assist the baking process, shorten the baking time in the large box, improve baking efficiency, save costs, and improve the quality of the baked tobacco leaves.

[0020] 2. The method of baking tobacco with a guide tube can shorten the baking time in a large box, improve baking efficiency, reduce energy consumption, save costs, and is easy to operate and highly reproducible.

[0021] 3. The overall quality of flue-cured tobacco has been improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of a front view of a tobacco drying rack with a guide tube;

[0023] Figure 2 It is a schematic structural diagram of a side view of a tobacco drying rack with a guide tube;

[0024] Figure 3 It is a schematic diagram of the structure of a mounting cap of a tobacco drying rack with a guide tube.

[0025] In the figure: 1. crossbeam; 2. high frame; 3. hook I; 4. guide tube; 5. fixing seat; 6. groove; 7. hook II; 8. air inlet; 9. tobacco rod; 10. round hole; 11. mounting cap; 12. low frame; 13. pointed head. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Embodiment 1, a tobacco drying rack with a guide tube, which comprises a frame body, on which a crossbeam 1, an elevated frame 2 and a low frame 12 are provided, the crossbeam 1 is provided with a groove 6, a tobacco rod 9 is placed on the groove 6, the elevated frame 2 and the low frame 12 are provided with a hook Ⅰ3, a guide tube 4 is provided on the hook Ⅰ3, a hook Ⅱ7 is provided on the guide tube 4, and the guide tube 4 is hung on the hook Ⅰ3 through the hook Ⅱ7; a circular hole 10 is provided on the guide tube 4; a fixing seat 5 is provided at one end of the tobacco rod 9, and a mounting cap 11 is provided at the other end of the tobacco rod 9, and the tobacco rod 9 is hung in the groove 6 on the crossbeam 1 through the fixing seat 5 and the mounting cap 11; a pointed head 13 is provided at the front end of the tobacco rod 9; the circular hole 10 on the guide tube 4 is spirally arranged; the elevated frame 2 and the low frame 12 are provided with an air inlet 8; a limiting rack is provided above the groove 6 and below the fixing seat 5 and the mounting cap 11 to prevent the tobacco rod 9 from moving.

[0028] Embodiment 2, a method for baking tobacco with a guide tube, using a tobacco drying rack with a guide tube to bake tobacco leaves, the steps are as follows: tobacco leaf harvesting, sorting and loading, tobacco leaf baking, tobacco leaf yellowing stage, tobacco leaf color fixing stage, tobacco leaf dry tendon stage and tobacco leaf rehumidification stage are controlled by controlling fire and wind during tobacco leaf baking, and the variety, nutritional level, part and maturity of fresh tobacco leaves in the same baking room are consistent during tobacco leaf sorting and loading.

[0029] Embodiment 3, a method for flue-cured tobacco with a guide tube, wherein the tobacco leaves harvested, arranged and loaded are selected from the lower tobacco leaves 10 days after topping, when the leaf color is mainly yellow-green, the leaf surface accounts for 55%, and the main veins turn white and 2 / 3 are harvested; the middle leaves are harvested 30 days after topping, when the leaf color is more yellow and less green, the leaf surface accounts for 75%, and the main veins turn white and 2 / 3 are harvested; the upper leaves are harvested 60 days after topping, when the leaf color is mainly yellow, the leaf surface accounts for more than 96%, and the main veins are basically completely white; 4 leaves are harvested from each plant each time, and harvesting is done every 6 days, and the maturity of the harvested tobacco leaves increases with the position, after the lower leaves are harvested, wait 6 days before harvesting the middle leaves, and after the middle leaves are harvested, wait 8 days Then pick the upper tobacco, and wait until the upper 6 left and right leaves are fully mature before picking them all at once, and the picking is completed in 5 times; when loading tobacco, 4500kg of lower leaves / furnace, 5000kg of middle leaves / furnace, and 5500kg of upper leaves / furnace, and each baking room has 10 tobacco boxes for each baking, with 500kg of lower tobacco per box, 550kg of middle tobacco, and 600kg of upper tobacco; use tobacco drying racks with guide pipes to achieve uniform ventilation during baking and blow through tobacco leaves; in the yellowing stage of tobacco leaves, the dry bulb temperature rises to 38°C at a rate of 1°C / h, and the wet bulb temperature is maintained at 38°C, and the temperature is stabilized. After the tobacco leaves turn yellow by about 60%, they are then heated at 0.8°C / h. The dry bulb temperature is raised to 40°C at a rate of 0.8°C / h, the wet bulb temperature is controlled at 38°C, and the temperature is stabilized to make the tobacco leaves sweat and soften. When the tobacco leaves turn 80% yellow, the dry bulb temperature is raised to 42°C at a rate of 0.8°C / h, the wet bulb temperature is maintained at 37°C, and the temperature is maintained for a longer time to make the tobacco leaves continue to turn yellow and lose water, and then enter the color fixing stage; in this stage, the yellowing degree of the lower tobacco leaves reaches 90% yellow, and the yellowing degree of the middle and upper tobacco leaves reaches 90% yellow. The yellow leaves of the tobacco leaves have blue veins and wither, and the main veins become soft and broken without breaking; in the color fixing stage of the tobacco leaves, the dry bulb temperature is raised to 45°C at a rate of 0.5°C / h, the wet bulb temperature is maintained at 38°C, and the temperature is stabilized to make the tobacco leaves curl and turn yellow. The dry bulb temperature is raised to 48℃ at a rate of 0.8℃ / h, the wet bulb temperature is controlled at 38℃, and the temperature is kept constant, so that the tobacco leaves reach the yellow-ribbed and yellow-sheet small roll; the dry bulb temperature is raised to 50℃ at a rate of 1℃ / h, the wet bulb temperature is controlled at 38℃, and the temperature is kept constant, so that the tobacco leaves are close to the large roll; the dry bulb temperature is raised to 54℃ at a rate of 1℃ / h, the wet bulb temperature is controlled at 39℃, and the temperature is kept constant, so that the tobacco leaves are rolled into large rolls, and then transferred to the dry-ribbed stage; in this stage, the tobacco leaves reach the yellow-ribbed and yellow-sheet stage, and the leaves are completely dry; in the dry-ribbed stage of the tobacco leaves, the dry bulb temperature is raised to 67℃ at a rate of 1℃ / h, and the tobacco clamping and tobacco increase by 1.5℃, and keep it stable, with the wet-bulb temperature controlled at 42℃, until the main veins of the tobacco leaves in the whole room are completely dry; if the main veins of the tobacco leaves dry too slowly in the middle and late stages of drying, artificially adjust the dry-bulb temperature to 67℃ and the wet-bulb temperature to 42℃, open and close the air inlet door intermittently, so that the wet-bulb temperature in the curing room fluctuates repeatedly within the range of 42℃, and the wet-bulb temperature is high for a short time, that is, it reaches 45℃, so that the dry-bulb temperature exceeds 68℃ for a short time. ℃, to accelerate the diffusion of moisture in the tobacco and promote the drying of the tobacco; in the tobacco leaf rehumidification stage, when the relative humidity of the outside air is high, after confirming that the tobacco leaves in the whole room are completely dry, stop the heating, turn off the fan power supply, and when the temperature of the curing room drops to 43℃, open the smoke loading door, cold air inlet and dehumidification port to allow the tobacco leaves to absorb moisture naturally and have an appropriate moisture content; when the relative humidity of the outside air is low, when the temperature of the curing room drops to 43℃, evenly sprinkle water on the floor of the smoke loading room and the heating room, then close the doors and windows of the curing room and the air inlet, turn on the fan for ventilation, and use the generated steam to increase the humidity of the circulating air to rehumidify the tobacco leaves. If the heating equipment has cooled down during the rehumidification, it will be heated again, and the temperature will be controlled at 43℃ to promote the vaporization of moisture so that the moisture content of the tobacco leaves is appropriate. The rest is the same as Example 2.

[0030] The time when tobacco leaves turn yellow should not be too long when the dry bulb temperature is below 35℃; moisture should be properly drained in the middle and late stages, depending on the wet bulb temperature and the changes in tobacco leaves, to prevent the tobacco leaves from becoming hard and yellow and rotting. During the color-fixing stage of tobacco leaves, the fire should be burned flexibly to prevent the temperature from rising too fast and falling too fast. The humidity should be stable and accurate, and be careful to prevent the wet bulb temperature from exceeding 40℃ or fluctuating. It is strictly forbidden to cool down sharply during the tobacco leaf drying stage to prevent the tobacco leaves from soaking; the maximum temperature and humidity of the drying tendons should be controlled to prevent the tobacco leaves from being roasted red.

[0031] Check the curing room before curing tobacco. Humidify the curing room at the initial stage of curing. If the moisture content of the harvested fresh tobacco leaves is low or the humidity in the curing room does not meet the requirements after the initial heating in the yellowing stage, open the door of the tobacco loading room or the inspection door of the hot air room, sprinkle a proper amount of clean water on the floor of the curing room, and appropriately extend the heating and ventilation time.

[0032] In the early stage of baking, the drying room should be dehumidified. When the harvested fresh tobacco leaves have a high moisture content, the initial heating temperature should be slightly increased, and the heating and ventilation time should be appropriately extended. Several intermittent dehumidifications should be carried out to allow a large amount of water attached to the leaf surface to evaporate before switching to normal baking.

[0033] If there is a power outage or motor damage and wind stop during baking, the standby power supply or motor replacement must be promptly replaced. Take effective fire suppression and fire extinguishing measures, including closing the fire door, closing the chimney damper, opening the inspection door, etc. If the power outage and wind stop fault cannot be eliminated in a short time, the fire should be suppressed and stopped, and the inspection door of the heating room and the smoke loading room of the baking room should be opened to ensure that the tobacco leaves are not burned and the lubrication of the fan is not damaged during the wind stop.

[0034] Use tobacco drying racks with air guide pipes to dry tobacco leaves. The quality of fresh tobacco in the whole room should be as consistent as possible. If it is not possible to achieve the same quality of fresh tobacco in the whole room, the quality of fresh tobacco on the same layer should be basically consistent. Fresh tobacco leaves that turn yellow quickly and over-ripe leaves are placed on the layer with the highest temperature, that is, the top layer of the airflow descending drying room and the bottom layer of the airflow ascending drying room. Fresh tobacco leaves with good quality are placed on the other two layers.

[0035] Ignition and burning. When burning, the fire power should be flexibly controlled according to the goals of each stage of baking and the requirements of the heating rate. Generally, a low fire is used in the initial stage of baking, a medium fire is used for small dehumidification, and a high fire is used for large dehumidification.

[0036] The fan is used for ventilation. The speed is low to medium when the tobacco leaves turn yellow. The speed is high when the temperature rises during the color fixing stage, and medium to high when the temperature is stable. The speed is changed to medium to low during the dry stage. It is recommended that automatic variable frequency speed control fans be used in tobacco growing areas where conditions permit.

[0037] The sensory smoking quality of tobacco leaves roasted in the above manner is improved, energy consumption is reduced, and costs are saved.

[0038] Table 1: Flushing process of middle and upper tobacco leaves

[0039]

[0040] Note: The cost of baking one large box of tobacco leaves in an automatic coal-adding energy-saving and environmentally friendly furnace is about 700 kg of coal (coal price is 0.86 yuan / kg), which is about 602 yuan, and 1,100 kWh of electricity (0.54 yuan / kWh) is 594 yuan, with a total cost of about 1,196 yuan. The amount of dry tobacco after baking is 650-700 kg, and the cost of dry tobacco after baking is 1.70 yuan / kg.

[0041] The data comparison table is as follows:

[0042] Table 2: Comparison of energy consumption of conventional baking in large ovens, baking in guide tubes and baking on hanging rods

[0043]

[0044] Note: Calculated based on electricity fee of 0.55 yuan / kWh and coal fee of 0.8 yuan / kg

[0045] Table 3: Comparison of sensory evaluation quality between large box baking and hanging baking

[0046]

Claims

1. A tobacco drying rack with a guide tube, characterized in that: The invention comprises a frame, wherein the frame is provided with a crossbeam (1), an elevated frame (2) and a low frame (12); the crossbeam (1) is provided with a groove (6); a tobacco rod (9) is placed on the groove (6); a hook I (3) is provided on the elevated frame (2) and the low frame (12); a flow guide tube (4) is provided on the hook I (3); a hook II (7) is provided on the flow guide tube (4); the flow guide tube (4) is suspended on the hook I (3) through the hook II (7); a circular hole (10) is provided on the flow guide tube (4); one end of the tobacco rod (9) is provided with a fixing seat ( 5), a mounting cap (11) is provided at the other end of the tobacco rod (9), and the tobacco rod (9) is suspended in a groove (6) on the crossbeam (1) through a fixing seat (5) and the mounting cap (11); a pointed head (13) is provided at the front end of the tobacco rod (9); the circular holes (10) on the guide tube (4) are arranged in a spiral arrangement; air inlets (8) are provided on the high frame (2) and the low frame (12); and a limiting rack is provided above the groove (6) and below the fixing seat (5) and the mounting cap (11) to prevent the tobacco rod (9) from moving.

2. A method for baking a flue-cured tobacco flow guide tube, characterized in that: The tobacco drying rack with a guide tube as described in claim 1 is used, and the steps are as follows: tobacco leaf harvesting, sorting, loading, and tobacco leaf baking. When baking the tobacco leaves, the yellowing stage, color fixing stage, dry tendon stage, and moisture regain stage of the tobacco leaves are controlled by controlling fire and wind. When the tobacco leaves are sorted and loaded, the variety, nutritional level, part, and maturity of the fresh tobacco leaves in the same baking room are consistent.

3. The method for baking tobacco using a flue-cured tobacco flow guide tube according to claim 2, characterized in that: The tobacco leaves harvested, sorted and packed are selected from the lower tobacco leaves 7-14 days after topping, when the leaf color is mainly yellow-green, the leaf surface accounts for 50-60% of yellow-green, and the main veins are more than 1 / 3 white, and are harvested; the middle leaves are harvested 21-35 days after topping, when the leaf color is more yellow and less green, the leaf surface accounts for 70-80%, and the main veins are more than 2 / 3 white, and are harvested; the upper leaves are harvested 56-63 days after topping, when the leaf color is mainly yellow, the leaf surface accounts for 90-100%, and the main veins are basically completely white; 3-4 leaves are harvested from each plant each time, and harvesting is done every 6-7 days. The maturity of the tobacco leaves harvested increases with the position, and the lower leaves are harvested at a lower maturity. After the lower part is harvested, wait 5-7 days before harvesting the middle part. After the middle part is harvested, wait 7-10 days before harvesting the upper part. The 6 left and right leaves of the upper part are harvested at one time after they are fully mature. The harvesting is completed in 4-5 times. When loading tobacco, the lower leaves ≥4500kg / furnace, the middle leaves ≥5000kg / furnace, and the upper leaves ≥5500kg / furnace. Each baking room has 10 tobacco boxes for loading each time. The lower tobacco box is 450-500kg, the middle tobacco is 500-550kg, and the upper tobacco is 550-600kg. Use tobacco drying racks with guide pipes to achieve uniform ventilation during baking and blow through the tobacco leaves.

4. The method for baking tobacco using a flue-cured tobacco flow guide tube according to claim 2, characterized in that: In the yellowing stage of tobacco leaves, the dry bulb temperature is raised to 38°C at a rate of 1°C / h, the wet bulb temperature is maintained at 37°C-38°C, the temperature is stabilized, and after the tobacco leaves turn 50%-60% yellow, the dry bulb temperature is raised to 40°C at a rate of 0.5°C-1°C / h, the wet bulb temperature is controlled at 37°C-38°C, the temperature is stabilized, the tobacco leaves sweat and become soft, when the tobacco leaves turn 80% yellow, the dry bulb temperature is raised to 42°C at a rate of 0.5°C-1°C / h, the wet bulb temperature is maintained at 36.5°C-37.5°C, the temperature is stabilized for a longer time, the tobacco leaves continue to turn yellow and lose water, and then enter the color fixing stage; in this stage, the yellowing degree of the lower tobacco leaves reaches 80%-90% yellow, the yellowing degree of the middle and upper tobacco leaves reaches 90%-100% yellow, the yellow leaves of the tobacco leaves have blue veins and wither, and the main veins become soft and broken but not broken.

5. The method for baking tobacco using a flue-cured tobacco flow guide tube according to claim 2, characterized in that: In the tobacco leaf color fixing stage, the dry bulb temperature is raised to 45°C at a speed of 0.5°C / h, the wet bulb temperature is maintained at 37°C-38°C, and the temperature is stabilized so that the tobacco leaf tips are curled; the dry bulb temperature is then raised to 47°C-48°C at a speed of 0.5°C-1°C / h, the wet bulb temperature is controlled at 37°C-38°C, and the temperature is stabilized so that the tobacco leaves reach the small roll with yellow tendons and yellow leaves; the dry bulb temperature is further raised to 50°C at a speed of 1°C / h, the wet bulb temperature is controlled at 37.5°C-38.5°C, and the temperature is stabilized so that the tobacco leaves approach the large roll; then the dry bulb temperature is raised to 54°C at a speed of 1°C / h, the wet bulb temperature is controlled at 38.5°C-39.5°C, and the temperature is stabilized so that the tobacco leaves are rolled into large rolls, and then the dry tendon stage is entered; in this stage, the tobacco leaves reach the yellow tendons and yellow leaves, and the leaves are completely dry.

6. The method for baking tobacco with a flue-cured tobacco flow guide tube according to claim 2, characterized in that: In the tobacco leaf drying stage, the dry-bulb temperature is raised to 65°C-68°C at a rate of 1°C / h, the tobacco clamping temperature is raised by 1°C-2°C and kept stable, and the wet-bulb temperature is controlled at 40°C-43°C until the main veins of all tobacco leaves in the room are completely dried; if the main veins of the tobacco leaves dry too slowly in the middle and late stages of drying, the dry-bulb temperature is manually adjusted to control the dry-bulb temperature at 65°C-68°C and the wet-bulb temperature at 40°C-43°C, and the air inlet door is opened and closed intermittently to make the wet-bulb temperature in the drying room fluctuate repeatedly within the range of 40°C-43°C, and the wet-bulb temperature is high for a short time, that is, reaching 45°C, so that the dry-bulb temperature exceeds 68°C for a short time to accelerate the diffusion of moisture in the tobacco leaves and promote the drying of the tobacco leaves.

7. The method for baking tobacco using a flue-cured tobacco guide tube according to claim 2, characterized in that: During the tobacco leaf rehumidification stage, when the relative humidity of the outside air is high, after confirming that all the tobacco leaves in the room are completely dry, stop heating, turn off the fan power supply, and when the temperature of the curing room drops to 40°C-45°C, open the smoke loading door, cold air inlet and dehumidification port to allow the tobacco leaves to absorb moisture naturally and have an appropriate moisture content; when the relative humidity of the outside air is low, when the temperature of the curing room drops to 40°C-45°C, evenly sprinkle water on the floors of the smoke loading room and the heating room, then close the doors and windows of the curing room and the air inlet, turn on the fan for ventilation, and use the generated steam to increase the humidity of the circulating air to rehumidify the tobacco leaves. If the heating equipment has cooled down during the rehumidification, it will be heated again, and the temperature will be controlled at 40°C-45°C to promote the vaporization of moisture so that the moisture content of the tobacco leaves is appropriate.

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