Biomass downflow intensive drying, ventilation and moisture conditioning method

Abstract

The application discloses a biomass down-draft dense baking ventilation and humidity adjusting method, which is an improvement on traditional baking technology and is designed according to tobacco baking characteristics and tobacco loading density and comprises the following steps: baking preparation - parameter setting, starting baking - manual small exhaust, automatic air intake - adjusting wet ball, top layer yellow soft - medium-speed circulation, strengthening moisture removal, middle layer yellow soft - adjusting humidity difference, manual air intake, high-speed circulation, bottom layer yellow soft - stable wet ball humidity difference, continuous ventilation and leaf curling - adjusting air intake, stable wet ball, main vein blue fading and semi-dry leaves - temperature adjustment and air adjustment, lower shelf stable humidity, main vein yellowing and dry leaves - reducing moisture removal and ventilation, medium-speed circulation main vein semi-dry - small moisture removal, small ventilation, low-speed circulation, and main vein dry. The method has strong operability, can reduce problems such as mold, ash, black dregs and baking green during the tobacco baking process, improves the appearance quality of tobacco leaves, makes the chemical components of the tobacco leaves more coordinated, and improves the tobacco yield and usability.

Description

Technical Field

[0001] This invention relates to a method for intensive curing, ventilation, and humidity control of biomass by descending process, belonging to the field of tobacco curing technology. Background Technology

[0002] Tobacco curing is the most crucial step in flue-cured tobacco production, determining the quality, yield, and usability of cigarettes. It is also a major factor directly impacting tobacco farmers' income and the quality and economic benefits of the cigarette industry. The quality, use value, and economic value of tobacco leaves are jointly determined by field growth management and scientific curing. Therefore, curing is of paramount importance in tobacco quality and flue-cured tobacco production. The curing characteristics, processes, and quality of flue-cured tobacco leaves are closely related and form the basis for developing suitable curing methods and creating optimal curing conditions to produce the best quality tobacco leaves.

[0003] Currently, in the process of intensive biomass drying, some smoke areas still use the traditional drying technology of low-temperature moisturizing and yellowing followed by rapid heating and large ventilation for color fixing and drying. The specific process is as follows:

[0004] The first step is to load the tobacco onto the kang (heated brick bed), close the doors and windows, set the baking curve parameters, adjust the baking curve status indicator box to the initial position, adjust the circulating fan to low speed, and start the fire for baking.

[0005] The second step is to maintain the starting dry and wet bulb temperatures at 32℃ for 16-24 hours. The program automatically controls the opening of the cold air inlet door and the dehumidification window blades. The circulating fan is kept at a low speed. After the top layer of tobacco leaves turns 50% yellow, the temperature is increased to 36℃ for both dry and wet bulbs at 1℃ / h. The temperature is maintained for 8-12 hours until the top layer of tobacco leaves turns 80% yellow and the leaves become swollen and hard.

[0006] The third step is to raise the temperature at 1℃ / h to 38℃ for dry bulb and 36.5-37℃ for wet bulb, and bake at a stable temperature for 8-12 hours. The opening of the cold air inlet door and the dehumidification window blades are controlled by the program, and the circulating fan is adjusted to medium speed. The middle layer of tobacco leaves is baked until they are 80% yellow and the leaves are half soft.

[0007] The fourth step is to keep the circulating fan at medium speed and raise the temperature at 1℃ / h to 40℃ for dry bulb and 37-38℃ for wet bulb. Maintain the temperature for 6-10 hours and control the opening of the cold air inlet and exhaust window blades. Bake until the bottom tobacco leaves are 80% yellow and half-soft.

[0008] Step 5: Increase the temperature at 1℃ / h to 42℃ for dry bulb and 37-38℃ for wet bulb, and bake at a stable temperature for 8-12 hours. Control the opening of the cold air inlet door and the dehumidification window blades in the program, and adjust the circulating fan to high speed. Bake until the bottom tobacco leaves turn yellow with green veins and the leaves soften.

[0009] Step 6: Increase the temperature to 44°C dry bulb temperature at a rate of 1°C / h, and maintain the temperature for 4-6 hours. During the temperature increase and stabilization period, manually keep the cold air inlet door at its maximum opening and continue to ventilate and dehumidify. Keep the wet bulb temperature at 30-32°C and run the circulating fan at high speed. Bake until the veins of the bottom tobacco leaves are half white and the leaves are curled.

[0010] Step 7: Increase the temperature at 1℃ / h to a dry bulb temperature of 48℃ and stabilize it for 6-8 hours. During the temperature increase and stabilization period, manually maintain the maximum opening of the cold air inlet door and continue to ventilate and dehumidify. Keep the wet bulb temperature at 30-32℃ and run the circulating fan at high speed to promote leaf drying. Bake until the main vein of the bottom tobacco leaves is still green and the leaves are half dry.

[0011] Step 8: Increase the temperature at 1℃ / h to 54℃ for dry bulb and stabilize for 8-12 hours. During the temperature increase and stabilization, manually keep the cold air inlet door at the maximum opening and continue to ventilate and dehumidify. Keep the wet bulb temperature at 32-34℃ and run the circulating fan at high speed until the main vein of the bottom tobacco leaves is still green and the leaves are completely dry.

[0012] Step 9: Increase the temperature to 60℃ at a rate of 1℃ / h and maintain the temperature for 6-10 hours. Manually keep the cold air inlet door at its maximum opening and continue to ventilate and dehumidify. Keep the wet bulb temperature at 32-34℃ and run the circulating fan at high speed until the main veins of the tobacco leaves are semi-dry.

[0013] Step 10: Increase the temperature to 65-68℃ at a rate of 1℃ / h and maintain the temperature for 24-36 hours. Manually keep the cold air inlet door at its maximum opening and continue to ventilate and dehumidify. When the wet bulb temperature is 32-34℃, run the circulating fan at high speed until the main veins of the bottom tobacco leaves are completely dry and then stop the fire.

[0014] However, traditional roasting techniques are prone to problems such as mold growth, mottled leaves, ash residue, black residue, floating green color, green veins, uneven color, and a large number of pale tobacco leaves after roasting. In particular, the problems of green and mixed tobacco leaves, uneven color, and pale color are more prominent, and it is necessary to improve them. Summary of the Invention

[0015] Based on the above, the present invention provides a biomass-based intensive curing ventilation and humidity control method. This method is suitable for the tobacco curing process and can solve problems such as mold, mottled leaves, ash residue, black residue, floating green color, green veins, uneven color, and pale color that occur in traditional intensive curing techniques, thereby improving the quality of tobacco curing.

[0016] The technical solution of this invention is: a biomass descending intensive baking, ventilation, and humidity control method, comprising the following steps:

[0017] The first step is to load the tobacco onto the kiln, close the doors and windows, set the baking process parameters, adjust the baking curve status indicator box to the initial position, adjust the circulating fan to the low speed setting, and start the baking process.

[0018] The second step is to maintain the starting dry and wet bulb temperatures at 32℃ for 4 hours of curing. After preheating the tobacco leaves, increase the temperature by 1℃ / h to 36℃ for the dry bulb and 35℃ for the wet bulb, and maintain the temperature for 8-14 hours. If the inner wall of the observation window of the curing barn is damp, manually hang up two leaves at the bottom of each of the left and right exhaust windows of the curing barn to form symmetrical small exhaust vents to remove moisture from the lower part of the shed. The program automatically controls the opening of the cold air inlet door and keeps the circulating fan at a low speed until the tips of the top leaves turn yellow and soften.

[0019] The third step is to raise the temperature at 1℃ / h to 38℃ for dry bulb and 35-37℃ for wet bulb, and bake at a stable temperature for 14-22 hours. Keep two leaves of each of the left and right dehumidification windows hanging up, and the program automatically controls the opening of the cold air inlet door. Keep the circulating fan at a low speed until the top layer of tobacco leaves turns yellow and softens in a coordinated manner, reaching 80% yellow and soft leaves.

[0020] The fourth step is to adjust the circulating fan to medium speed and raise the temperature at 1℃ / 2h to 40℃ for dry bulb and 35-36℃ for wet bulb. Maintain the temperature for 12-16h. If the inner wall of the observation window glass becomes damp during this period, hang up four blades on each side of the dehumidification window to form two small dehumidification outlets on each side. The program will automatically control the opening of the cold air inlet door. Bake until the middle layer tobacco leaves are 80% yellow and the leaves are soft, and until the top layer leaves are yellow and the main veins are soft.

[0021] Step 5: Increase the temperature by 1℃ / 2h to 42℃ for dry bulbs and 35-36℃ for wet bulbs, and maintain the temperature for 16-22h. Manually control the opening of the cold air inlet door to continuously ventilate and dehumidify, keep the wet bulb temperature of the lower shed at 35-36℃, and adjust the circulating fan to high speed to coordinate the yellowing and drying of the middle and upper layers, until the top layer of tobacco leaves reaches the point where the veins turn white and the tips curl, and the bottom layer reaches the point where the leaves are yellow with green veins and the main veins soften.

[0022] Step 6: Increase the temperature to 44°C dry bulb temperature by 1°C / 2-3 hours, and stabilize the temperature for 8-12 hours. During the temperature increase, manually and gradually open the cold air inlet until the actual wet bulb temperature is consistent with the target value of 35-36°C and stabilizes. Continue ventilation to remove moisture and maintain the target wet bulb temperature of 35-37°C. Keep the circulating fan at high speed. Bake until the veins of the bottom tobacco leaves turn white and the tips curl.

[0023] Step 7: Increase the temperature to 48°C dry bulb temperature by 1°C / 2-3 hours and stabilize the temperature for 12-18 hours. During the temperature increase and stabilization, continue to ventilate and dehumidify to maintain the target wet bulb temperature of 35-36°C. Keep all the leaves of the left and right dehumidification windows hanging up and use the high speed setting of the circulating fan to bake until the main vein of the bottom tobacco leaves turns from green to white and the leaves are half dry.

[0024] Step 8: Increase the temperature at 1℃ / 2h to 54℃ dry bulb temperature and stabilize it for 10-18h. During the temperature increase and stabilization, manually and gradually open the cold air inlet until the actual wet bulb temperature value is consistent with the target value and stabilizes. Continue ventilation and dehumidification to maintain the target wet bulb temperature of 35-37℃. Keep the circulating fan running at high speed and keep all leaves of the left and right dehumidification windows hanging up. Bake until the main vein of the bottom tobacco leaves turns yellow and the leaves are completely dry.

[0025] Step 9: Increase the temperature to 60℃ at 1℃ / h and stabilize it for 6-10 hours. Lower the four blades at the bottom of each of the left and right exhaust windows, manually close the cold air inlet door to reduce ventilation and dehumidification, maintain the wet bulb temperature at 37-39℃, adjust the circulating fan to medium speed, and bake until the main vein of the tobacco leaves shrinks and turns purple, and it is half dry.

[0026] Step 10: Increase the temperature to 65-68℃ at a rate of 1℃ / h and maintain the temperature for 24-36 hours. Lower all the blades of the left and right exhaust windows, manually close the cold air inlet door, leaving a gap to reduce ventilation and dehumidification. Keep the wet bulb temperature at 38-40℃, adjust the circulating fan to low speed, and bake until the main veins of the top layer of tobacco leaves are completely dry before stopping the fire.

[0027] Preferably, in the first step, the tobacco leaves used in the same kiln are of the same variety, and the maturity of the tobacco leaves in the same layer is consistent. They are then loaded into high, medium, and low temperature layers according to their maturity levels, with the top layer being denser and the bottom layer sparser, ensuring that the layers are full and evenly packed.

[0028] Preferably, in the first step, the baking process parameters are ten target dry-bulb stable temperature points: the first stable temperature point has a dry-bulb temperature of 32℃ and a wet-bulb temperature of 32℃, stabilized for 4 hours, and a heating time of 4 hours; the second stable temperature point has a dry-bulb temperature of 36℃ and a wet-bulb temperature of 35℃, stabilized for 4-10 hours, and a heating time of 2 hours; the third stable temperature point has a dry-bulb temperature of 38℃ and a wet-bulb temperature of 35-36℃, stabilized for 12-20 hours, and a heating time of 4 hours; the fourth stable temperature point has a dry-bulb temperature of 40℃ and a wet-bulb temperature of 35-36℃, stabilized for 8-12 hours, and a heating time of 4 hours; and the fifth stable temperature point has a dry-bulb temperature of 42℃ and a wet-bulb temperature of 35-36℃, stabilized for 12-18 hours. The heating time is 4-6 hours. The sixth stable temperature point has a dry-bulb temperature of 44℃ and a wet-bulb temperature of 35-36℃. The temperature remains stable for 8-12 hours, and the heating time is 8-12 hours. The seventh stable temperature point has a dry-bulb temperature of 48℃ and a wet-bulb temperature of 35-36℃. The temperature remains stable for 12-18 hours, and the heating time is 12 hours. The eighth stable temperature point has a dry-bulb temperature of 54℃ and a wet-bulb temperature of 35-36℃. The temperature remains stable for 10-18 hours, and the heating time is 6 hours. The ninth stable temperature point has a dry-bulb temperature of 60℃ and a wet-bulb temperature of 37-39℃. The temperature remains stable for 6-10 hours, and the heating time is 5-8 hours. The tenth stable temperature point has a dry-bulb temperature of 65-68℃ and a wet-bulb temperature of 38-40℃. The temperature remains stable for 24-36 hours.

[0029] Preferably, the circulating fan has a low speed setting of 720 r / min, a medium speed setting of 960 r / min, and a high speed setting of 1440 r / min.

[0030] Preferably, in step five, if the wet-bulb temperature difference between the upper and lower greenhouses exceeds 0.5℃ during the temperature stabilization period, hang up six leaves on the upper part of each of the left and right exhaust windows to form three small exhaust vents on each side symmetrically, maintaining the humidity difference between the upper and lower greenhouses within 0.5℃.

[0031] Preferably, in step six, if the inner wall of the observation window becomes damp during the heating process, hang up all the blades of the left and right dehumidification windows to keep the wet-bulb humidity difference between the upper and lower sheds within 0.5℃.

[0032] Preferably, in steps seven and eight, if the inner wall of the observation window glass becomes damp during the heating process, manually open the cold air intake door until the wet-bulb temperature of the lower shed reaches 35-36℃ and the moisture on the inner wall of the observation window glass disappears.

[0033] The applicant's research revealed the following problems with the traditional biomass intensive curing technology: low-temperature, moisturizing, slow yellowing, rapid heating, and high ventilation for color fixing and drying. In the early yellowing stage, the dry-bulb temperature is 32-36℃, and the wet-bulb temperature is the same. The cold air inlet and exhaust vents are closed, resulting in poor ventilation and prolonged curing time. The top layer of tobacco leaves remains 80% yellow but does not soften, while the bottom layer is prone to mold. In the middle yellowing stage, the dry-bulb temperature reaches 38℃, and the wet-bulb temperature is 36.5-37℃. Ventilation and dehumidification are then necessary. In the initial stage of yellowing, the dry-bulb temperature is raised to 40-42℃ and the wet-bulb temperature is raised to 37-38℃. With minimal ventilation and moisture removal, the bottom layer of tobacco leaves is roasted until they turn yellow with green veins and become soft. This process also results in a high likelihood of ash and black residue buildup. In the early stage of color fixing, the dry-bulb temperature is increased to 44℃ at a rate of 1℃ per hour and maintained for 4-6 hours. The cold air inlet is opened to its maximum, maintaining a wet-bulb temperature of 30-32℃. The dry-bulb temperature is then increased to 48℃ at a rate of 1℃ per hour and maintained for 6-8 hours. For the first hour, keep the cold air inlet at maximum opening, maintain a wet-bulb temperature of 30-32℃, and bake until the main veins of the bottom tobacco leaves are still green and the leaves are semi-dry. Use a relatively fast heating rate, low humidity, and large ventilation to promote the drying and color setting of the tobacco leaves. After baking, there are many tobacco leaves with floating green, green veins, ash, black residue, and uneven color. In the later stage of color setting, increase the dry-bulb temperature to 54℃ at a rate of 1℃ per hour and stabilize the temperature for 8-12 hours. Keep the cold air inlet at maximum opening, maintain a wet-bulb temperature of 32-34℃, and bake until the leaves are completely dry. After baking, there are many tobacco leaves with uneven color. There are more tobacco leaves with large color differences; in the early stage of drying, the dry bulb temperature is increased to 60℃ at a rate of 1℃ per hour and maintained for 6-10 hours, with the cold air inlet valve kept at its maximum opening and the wet bulb temperature at 32-34℃. The tobacco leaves are baked until the main vein is half dry, resulting in more light-colored tobacco leaves after baking; in the later stage of drying, the dry bulb temperature is increased to 65-68℃ at a rate of 1℃ per hour and maintained for 24-36 hours, with the cold air inlet valve kept at its maximum opening and the wet bulb temperature kept at 32-34℃. The tobacco leaves are baked until the main vein is completely dry and the fire is stopped, resulting in more light-colored tobacco leaves after baking.

[0034] The beneficial effects of this invention are as follows: Addressing the problems of mold, ash buildup, black residue, floating green color, green veins, uneven color, and excessive pale tobacco leaves after traditional curing techniques, this invention, based on the characteristics of tobacco curing, the density of tobacco packing, and changes during the curing process, reduces these problems in biomass-based intensive curing by manually adjusting the opening of the dehumidification window and the cold air inlet, along with adjustments to the circulating fan speed and wet-bulb temperature. According to the applicant's experiments, this invention can reduce mold, ash buildup, black residue, floating green color, green veins, uneven color, and pale color that occur in biomass-based intensive curing. In particular, it solves the problems of green and impure tobacco leaves, uneven color, and pale color, thus improving the quality of tobacco curing. Detailed Implementation

[0035] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] First, let's describe the curing barn. Existing descending, intensive curing barns include a heating chamber and a tobacco loading chamber. An observation window is installed on the side of the loading chamber closest to the heating chamber. A cold air inlet is located on the lower part of one side of the heating chamber. The opening of the cold air inlet can be automatically controlled by the curing program or manually. Dehumidification louvers are installed on both sides of the loading chamber closest to the heating chamber, with eight louvers on each side.

[0037] This invention discloses a method for intensive drying, ventilation, and humidity control of biomass using a descending heating process, comprising the following steps:

[0038] The first step is pre-curing preparation. Before loading the tobacco into the curing barn, remove any accumulated dust from the heating equipment, ensure the curing barn enclosure is airtight, seal the heating equipment to prevent smoke leakage, and ensure the equipment is powered on and functioning properly. Harvest tobacco leaves according to the current mature harvest standards, sort and bundle (clamp) them, and load them into the curing barn. Install the sensors in place.

[0039] In this step, the lower tobacco leaves are harvested when they are predominantly green with a hint of yellow, the middle tobacco leaves are harvested when they are yellowish-green or half yellowish-green, and the upper tobacco leaves are harvested when they are predominantly yellow with a hint of green. The leaves are then sorted and bundled, with each bundle containing approximately 60 bundles of leaves of the same type and maturity. Each bundle contains about 2-3 leaves, and each bundle contains the same number of leaves, ensuring they are fully and evenly packed. This ensures that the leaves on the same bundle exhibit consistent growth. The tobacco leaves are then integrated and loaded into the curing barn. The same variety of tobacco leaves are loaded into the same layer, ensuring consistent maturity. They are then placed in the high, medium, and low temperature layers of the curing barn according to their maturity level, with a denser top and sparser bottom, ensuring they are fully and evenly packed. Each layer contains approximately 100 bundles, ensuring consistent growth. Finally, the sensors are installed: a water bottle is filled with clean water, and clean, absorbent cotton yarn is used to wrap the wet-bulb thermometer bulb at the top and place the entire bottom of the yarn into the water bottle. The temperature and humidity sensors are installed in the corresponding positions on the bottom and top of the curing barn.

[0040] The second step is to set the parameters and ignite the oven for baking. After loading the oven, close the doors and windows. After powering on the electrical equipment, set the dry bulb temperature display box on the left side of the automatic controller display to "upper rack". Set ten target dry bulb temperature stabilization points according to the current baking process. Combine the baking characteristics of the tobacco leaves in the lower, middle and upper parts and the tobacco loading density, and set the corresponding target wet bulb temperature, stabilization time, heating time and other parameters. The specific baking plan parameters are shown in Table 1 below. After setting the parameters, adjust the baking curve status indicator box to the initial position, adjust the circulating fan to low speed, and ignite the oven for baking.

[0041] Baking plan parameters

[0042]

[0043] In this step, the left side of the dry bulb temperature display box is set to "upper rack," displaying the actual temperature and humidity values ​​of the tobacco leaves on the upper rack during baking. The baking curve serves to prevent large fluctuations in the baking temperature and humidity environment, which could affect the quality of the tobacco leaves. The baking curve status indicator box is adjusted to its initial position to prevent the indicator box from being in other positions where the ignition temperature is high, causing the tobacco leaves to turn green. The circulating fan is adjusted to a low speed to open the ventilation duct and promote hot air circulation. The baking curve parameters are characterized by the dry bulb temperature at the last stable temperature point, the lower limit of the baking time for lower tobacco leaves, the middle value for middle leaves, the upper limit for upper leaves, the lower limit of the wet bulb temperature for tobacco leaves with poor baking characteristics in the upper and lower parts or dense packing, and the upper limit of the wet bulb temperature for tobacco leaves with good baking characteristics in the middle and upper parts or sparse packing.

[0044] The third step involves manual ventilation and automatic air intake. After preheating the tobacco leaves by maintaining the initial target dry-bulb and wet-bulb temperatures at 32℃ for 4 hours, maintain a temperature increase of 1℃ / h, with dry-bulb temperatures at 36℃ and wet-bulb temperatures at 35℃ for 8-14 hours. If the inner wall of the observation window in the curing barn is damp, manually hang up two leaves from the lower part of each of the left and right exhaust windows to create symmetrical small exhaust vents, removing moisture from the lower part of the curing barn and preventing moisture accumulation that could cause mold growth. The program automatically controls the opening of the cold air intake door, and the circulating fan remains at a low speed until the tips of the top leaves turn yellow and soften.

[0045] Step 4: Adjust the wet-bulb temperature until the top leaf tips turn yellow and soften. After the top leaf tips turn yellow and soften, maintain a temperature increase of 1℃ / h, dry bulb temperature of 38℃, and wet bulb temperature of 35-36℃ for 14-22 hours. Keep two leaves hanging on each side of the dehumidification window, control the opening of the cold air inlet damper according to the program, and keep the circulating fan at a low speed. During the temperature stabilization period, adjust the wet-bulb temperature value to coordinate the yellowing and softening of the top tobacco leaves, achieving 80% yellowing and softening. Prevent the tobacco leaves from turning too yellow, resulting in insufficient water loss and ash or rotten leaves, or from not yellowing enough and losing too much water, resulting in green curing.

[0046] Step 5: Medium-speed circulation to enhance dehumidification and soften the middle layer of tobacco leaves. After the top layer of tobacco leaves has turned 80% yellow and softened, adjust the circulation fan to medium speed to promote the yellowing and softening of the middle layer of tobacco leaves, preventing ash buildup, rotten leaves, and brittle leaves. Maintain a temperature increase of 1℃ / 2 hours, dry bulb temperature of 40℃, and wet bulb temperature of 35-36℃ for 12-16 hours. If the inner wall of the observation window glass becomes damp during this period, hang up four blades at the bottom of each of the left and right dehumidification windows to form two small dehumidification vents on each side. Control the opening of the cold air inlet valves according to the program. The middle layer of tobacco leaves will turn 80% yellow and soften, and the top layer will turn yellow and soften the main veins.

[0047] Step 6: Adjust the humidity difference, manually introduce air, and circulate at high speed until the bottom layer of tobacco leaves turns yellow and soft. After 80% of the middle layer of tobacco leaves have turned yellow and softened, maintain a temperature increase of 1℃ / 2h, dry bulb temperature of 42℃, and wet bulb temperature of 35-36℃ for 16-22h. During the temperature stabilization period, if the wet bulb temperature difference between the upper and lower sheds exceeds 0.5℃, hang six leaves from the lower part of each of the left and right exhaust windows to form three small exhaust vents on each side, maintaining the humidity difference between the upper and lower sheds within 0.5℃ to prevent the lower layer of tobacco leaves from accumulating ash, becoming mushy, or turning green. Manually control the opening of the cold air inlet door for continuous ventilation and dehumidification, maintaining the wet bulb temperature of the upper shed at 35-36℃. Adjust the circulating fan to high speed to coordinate the yellowing and drying of the middle and upper layers, preventing ash, mushy, and turning green. The top layer of tobacco leaves will reach the point where the veins turn white and the tips curl, while the bottom layer will reach the point where the leaves are yellow with green veins and the main veins soften.

[0048] Step 7: Stabilize wet-bulb temperature and adjust humidity difference, maintain ventilation and leaf curling. After the bottom layer of tobacco leaves turns yellow with green veins and the midrib softens, maintain a temperature of 1℃ for 2-3 hours to raise the temperature to a stable dry-bulb temperature of 44℃. During the temperature rise, if the inner wall of the observation window is damp, hang all the leaves of the left and right exhaust windows to keep the wet-bulb humidity difference between the upper and lower shelves within 0.5℃ to prevent the lower layer of tobacco leaves from developing ash and black spots. Manually and gradually increase the opening of the cold air inlet until the actual wet-bulb temperature value matches the target value of 35-36℃ and then stabilize. During the temperature stabilization period, keep the circulating fan at high speed to maintain the wet-bulb temperature difference between the upper and lower shelves within 0.5℃, keep the cold air inlet and exhaust windows open, and continue ventilation and dehumidification to maintain the target wet-bulb temperature of 35-36℃, promoting the drying of the middle and upper layers of leaves and the whitening of the midrib, preventing ash, black spots, green veins, and re-greening. Stabilize the temperature at 44℃ for 8-12 hours, and the branch veins of the bottom layer of tobacco leaves will turn white and the tips will curl.

[0049] Step 8: Adjust airflow, stabilize wet-bulb temperature, and ensure the main veins of the tobacco leaves turn pale and the leaves are half-dry. After the veins of the bottom tobacco leaves turn white and the tips curl, maintain a temperature of 1℃ for 2-3 hours to raise the temperature to a stable dry-bulb temperature of 48℃. During the temperature rise, if the inner wall of the observation window glass is damp, manually open the cold air inlet until the wet-bulb temperature of the lower shed reaches 35-36℃ and the moisture on the inner wall of the observation window glass disappears. During the temperature stabilization period, maintain the opening of the cold air inlet to maintain the wet-bulb temperature of the lower shed at 35-36℃. During the temperature rise and stabilization period, continue ventilation to remove moisture, maintaining the target wet-bulb temperature at 35-36℃. Keep all the leaves of the left and right dehumidification windows hanging, and keep the circulating fan at high speed to promote leaf drying, prevent dust, black residue, and green veins, and promote the whitening of the main veins of the tobacco leaves, dryness of the leaves, and uniform and bright color. Baking at a stable temperature of 48℃ for 12-18 hours will result in the main veins of the bottom tobacco leaves turning pale and white, and the leaves being half-dry.

[0050] Step 9: Increase temperature and adjust ventilation, stabilize humidity in the lower shed, and ensure the main veins turn yellow and the leaves are completely dry. After the main veins of the bottom tobacco leaves turn from green to white and half of the leaves are dry, maintain a temperature of 1℃ / 2 hours to increase the temperature to a stable dry-bulb temperature of 54℃. During the temperature increase, if there is moisture on the inner wall of the observation window, manually open the cold air inlet door to increase its opening. Once the moisture on the inner wall of the observation window disappears, maintain the wet-bulb temperature in the lower shed at 35-36℃. During the temperature stabilization period, maintain the opening of the cold air inlet door and maintain the wet-bulb temperature in the lower shed at 35-36℃. During the temperature increase and stabilization periods, continue ventilation to remove moisture, maintaining the target wet-bulb temperature at 35-36℃. Keep all leaves of the left and right dehumidification windows hanging, and keep the circulating fan at high speed to promote the drying and color setting of the tobacco leaves, preventing scorching, green veins, and dark color. Baking at a stable temperature of 54℃ for 10-18 hours will result in the main veins of the bottom tobacco leaves turning yellow and the leaves being completely dry.

[0051] Step 10: Reduce humidity and ventilation, maintain medium-speed circulation until the midrib is partially dry. After the midrib of the bottom tobacco leaves turns yellow and the leaves are completely dry, maintain a temperature increase of 1℃ / h to a stable 60℃. Lower four leaves from the upper part of each of the left and right exhaust windows, manually close the cold air inlet damper to reduce ventilation and humidity removal, maintaining a wet-bulb temperature of 37-39℃. Adjust the circulating fan to medium speed to promote midrib drying and prevent the tobacco leaves from becoming pale. Maintain a stable 60℃ temperature for 6-10 hours until the midrib of the tobacco leaves shrinks and turns purple, and is half-dry. In this step, manually closing the exhaust windows and cold air inlet damper provides appropriate humidity, which is beneficial for improving the color of the tobacco leaves and drying the midrib. Avoid letting the sensor water tank dry out, which would cause the cold air inlet damper to open wide, affecting the tobacco curing quality and wasting fuel.

[0052] Step 11: Minimal dehumidification, minimal ventilation, low-speed circulation, and complete drying of the main vein. After the main vein of the tobacco leaves shrinks and turns purple, and is half-dried, maintain a temperature increase of 1℃ / h to a stable temperature of 65-68℃. Lower all the blades of the left and right dehumidification windows, manually close the cold air inlet door slightly (manually close the cold air inlet door slightly, but do not close it completely, leave a small gap), reduce ventilation and dehumidification, maintain the wet-bulb temperature at 38-40℃, adjust the circulating fan to a low speed to promote the drying of the main vein, improve the color, save fuel, prevent low-humidity tobacco leaves from becoming pale, and prevent high-humidity tobacco leaves from turning red. Stop the fire too early to allow the veins to heal. Maintain a stable temperature of 65-68℃ for 24-36 hours, until the main vein of the bottom layer of tobacco leaves is completely dry (the main vein from the stem end to the tip is completely shrunken, purple, and dry, and can be easily broken by hand). Stop the fire.

[0053] The baking effect of the present invention will be verified by the following experiment:

[0054] The experiment was conducted in Liupanshui City, Guizhou Province in 2022. The tested flue-cured tobacco variety was Yunyan 87, and the upper leaves were used as the experimental material. The tested tobacco leaves were cultivated and managed according to the local standardized practices for high-quality tobacco production, and harvested at maturity according to the standards and procedures for tobacco leaf maturity. The tested curing barn was a descending, intensive curing barn. A comparative experiment was conducted using the traditional curing technology as a control and the curing process of this invention as a comparative treatment. Except for the process conditions, all other factors, such as the curing barn structure, tobacco variety, quantity, and packing density, were the same.

[0055] Traditional baking process:

[0056] The first step is to load the tobacco onto the drying rack, placing it in the high, medium, and low temperature layers of the drying room according to its maturity level (high, medium, and low), with a denser layer at the bottom and a sparser layer at the top, filling the rack completely and evenly. Four layers are used, for a total of 420 racks. Set the drying program parameters as shown in Table 2 below. After setting the parameters, adjust the drying curve status indicator box to its initial position, adjust the circulating fan to low speed, and ignite the drying process.

[0057] Table 2 Baking Plan Parameters

[0058]

[0059] The second step involves consistent temperature and humidity, with the leaves turning yellow at low temperatures and the top layer becoming yellow and hard. Maintain the initial dry and wet bulb temperatures at 32℃ for 24 hours of baking. The program automatically controls the opening of the cold air inlet and exhaust window blades, and the circulating fan remains at low speed. Once the top layer of tobacco leaves is 50% yellow, maintain a temperature increase of 1℃ / h to 36℃ for both the dry and wet bulbs, and bake at a stable temperature for 12 hours until the top layer of tobacco leaves is 80% yellow and the leaves are swollen and hard.

[0060] The third step is to moisturize and allow the leaves to turn yellow, then circulate at medium speed until the middle layer is semi-soft. When the top layer of tobacco leaves is 80% yellow and firm, the circulating fan is adjusted to medium speed, and the opening of the cold air inlet and exhaust window blades is controlled by the program. The temperature is maintained at 1℃ / h to reach 38℃ for dry bulb and 37℃ for wet bulb. The leaves are then baked at a stable temperature for 12 hours until the middle layer of tobacco leaves are 80% yellow and semi-soft.

[0061] Step 4: Moisturize and yellow the leaves, and soften the bottom layer. After the middle layer of tobacco leaves are 80% yellow and the leaves are half-soft, keep the circulating fan at medium speed, control the opening of the cold air inlet and exhaust window blades in the program, maintain a temperature increase of 1℃ / h to 40℃ for dry bulb and 38℃ for wet bulb, and bake at a stable temperature for 10 hours until the bottom layer of tobacco leaves are 80% yellow and the leaves are half-soft.

[0062] Step 5: Moisturize and yellow the leaves, soften the bottom layer. After 80% of the bottom tobacco leaves turn yellow and the leaves are half-soft, control the opening of the cold air inlet and exhaust window blades, adjust the circulating fan to high speed, maintain a temperature increase of 1℃ / h to 42℃ for dry bulb and 38℃ for wet bulb, and bake at a stable temperature for 12 hours until the bottom tobacco leaves turn yellow with green veins and the leaves soften.

[0063] Step 6: Rapidly increase temperature, increase ventilation, and curl the bottom layer of tobacco leaves. After the bottom layer of tobacco leaves turns yellow with green veins and the leaves soften, manually keep the cold air inlet door at its maximum opening, continuously increase ventilation to remove moisture, and run the circulating fan at high speed; maintain a temperature increase of 1℃ / h to 44℃ dry bulb, stabilize the temperature for 6 hours, and during the temperature increase and stabilization period, keep the wet bulb temperature at 32℃, until the veins of the bottom layer of tobacco leaves are half white and the leaves curl up.

[0064] Step 7: Rapidly increase temperature and ensure ample ventilation until the main veins are still green and the leaves are semi-dry. After the veins of the bottom tobacco leaves are half-white and the leaves are curled, manually maintain the maximum opening of the cold air inlet door and continue to ventilate and dehumidify. Maintain a temperature increase of 1℃ / h until the dry bulb temperature reaches 48℃ and bake at a stable temperature for 8 hours. During the temperature increase and stabilization period, the wet bulb temperature is 32℃, and the circulating fan runs at high speed to promote leaf drying. Bake until the main veins of the bottom tobacco leaves are still green and the leaves are semi-dry.

[0065] Step 8: Rapidly increase temperature, increase ventilation, and dry the leaves completely. After the main veins of the bottom tobacco leaves are still green and the leaves are half-dry, manually keep the cold air inlet door at its maximum opening and continue to ventilate and dehumidify. Maintain a temperature increase of 1℃ / h until the dry bulb temperature reaches 54℃ and remains stable for 12 hours. During the temperature increase and stabilization period, the wet bulb temperature is 34℃, and the circulating fan runs at high speed until the main veins of the bottom tobacco leaves are still green and the leaves are completely dry.

[0066] Step 9: Maximum ventilation, midrib partially dry. After the midribs of the bottom tobacco leaves are still green and the leaves are completely dry, manually keep the cold air inlet door at maximum opening, continuously ventilate to remove moisture, maintain a temperature of 1℃ / h to 60℃ and stabilize for 10 hours, wet bulb temperature 34℃, and run the circulating fan at high speed until the midribs of the tobacco leaves are partially dry;

[0067] Step 10: Maximum ventilation until the main veins are completely dry. After the main veins of the tobacco leaves are half-dry, manually maintain the cold air inlet damper at its maximum opening and continue to ventilate and dehumidify. Maintain a temperature rise of 1℃ / h to 68℃ and stabilize at that temperature for 36 hours. With the wet-bulb temperature at 34℃, run the circulating fan at high speed until the main veins of the bottom layer of tobacco leaves are completely dry and then stop the fire.

[0068] Baking process of this invention:

[0069] The first step is to load the tobacco onto the drying rack, placing it in the high, medium, and low temperature layers of the drying room according to its maturity level (high, medium, and low), with a denser layer at the bottom and a sparser layer at the top, filling the rack completely and evenly. Four layers are used, for a total of 420 racks. Set the drying program parameters as shown in Table 3 below. After setting the parameters, adjust the drying curve status indicator box to its initial position, adjust the circulating fan to low speed, and ignite the drying process.

[0070] Table 3 Baking Plan Parameters

[0071]

[0072] The second step involves manual small-scale ventilation and automatic air intake. After preheating the tobacco leaves by maintaining the initial target dry-bulb and wet-bulb temperatures at 32℃ for 4 hours, maintain a temperature increase of 1℃ / h, with dry-bulb temperatures at 36℃ and wet-bulb temperatures at 35℃ for 8 hours. When the inner wall of the observation window in the curing barn becomes damp, manually hang up two leaves from the lower part of each of the left and right exhaust windows to form symmetrical small exhaust vents, removing moisture from the lower part of the curing barn and preventing moisture accumulation that could cause mold growth. The program automatically controls the opening of the cold air inlet door, and the circulating fan remains at a low speed, maintaining a dry-bulb temperature of 36℃ and a wet-bulb temperature of 35℃ for 6 hours, until the tips of the top leaves turn yellow and soften.

[0073] The third step is to adjust the wet-bulb temperature until the top leaves turn yellow and soften. After the tips of the top leaves turn yellow and soften, maintain a temperature increase of 1℃ / h, with a dry-bulb temperature of 38℃ and a wet-bulb temperature of 36℃ for 12 hours. When the top leaves are 60% yellow and 1 / 3 have softened, adjust the wet-bulb temperature to 35℃ to promote further softening. Keep two leaves hanging on each of the left and right exhaust windows, control the opening of the cold air inlet valve using the program, and keep the circulating fan at a low speed. Maintain a dry-bulb temperature of 38℃ and a wet-bulb temperature of 35℃ for another 10 hours. When the top leaves are 80% yellow and softened, avoid excessive yellowing (insufficient water loss leading to ash) or insufficient yellowing and excessive water loss (causing greening).

[0074] Step 4: Medium-speed circulation to enhance dehumidification and soften the middle layer of tobacco leaves. After the top layer of tobacco leaves has turned 80% yellow and softened, adjust the circulating fan to medium speed to promote the yellowing and softening of the middle layer of tobacco leaves and prevent ash buildup and greening during curing. Maintain a temperature increase of 1℃ / 2 hours, dry bulb temperature of 40℃, and wet bulb temperature of 36℃ for 6 hours. When the inner wall of the observation window glass is moist, hang up four blades at the bottom of each of the left and right dehumidification windows to form two small dehumidification vents on each side, reducing the humidity in the curing barn. Control the opening of the cold air inlet door according to the program and maintain a dry bulb temperature of 40℃ and a wet bulb temperature of 36℃ for another 10 hours. The middle layer of tobacco leaves will turn 80% yellow and soften, and the main veins of the yellow leaves at the top layer will soften.

[0075] Step 5: Adjust the humidity difference, manually introduce air, and circulate at high speed until the bottom layer of tobacco leaves turns yellow and softens. After 80% of the middle layer of tobacco leaves have turned yellow and softened, maintain a temperature increase of 1℃ / 2h, dry bulb temperature of 42℃, and wet bulb temperature of 36℃ for 6 hours of baking. When the wet bulb temperature difference between the upper and lower shelves exceeds 0.5℃, hang up six leaves at the bottom of each of the left and right exhaust windows to form three small exhaust vents on each side, reducing the humidity in the lower shelf and keeping the humidity difference between the upper and lower shelves within 0.5℃ to prevent the lower layer of tobacco leaves from being covered with ash and becoming blanched. Manually control the opening of the cold air inlet door for continuous ventilation and dehumidification, maintaining the wet bulb temperature of the upper shelf at 36℃. Adjust the circulating fan to high speed to coordinate yellowing and drying, preventing ash buildup and blanching. Maintain a dry bulb temperature of 42℃ and a wet bulb temperature of 36℃ for another 16 hours of baking. The veins of the top layer of tobacco leaves will turn white and the tips will curl, while the bottom layer of yellow leaves will have green veins and the main veins will soften.

[0076] Step 6: Stabilize wet-bulb temperature and adjust humidity difference, maintain ventilation and leaf curling. After the bottom layer of tobacco leaves turns yellow with green veins and the midrib softens, maintain a temperature of 44℃ (dry bulb) at 1℃ / 3 hours. During the temperature rise, observe the moisture level inside the observation window, hang all the leaves of the left and right exhaust windows to remove moisture from the lower layer, ensuring the wet-bulb humidity difference between the upper and lower shelves is within 0.5℃ to prevent the lower layer of tobacco leaves from ash buildup, steaming, burning, and re-greening. Manually and gradually increase the opening of the cold air inlet until the actual wet-bulb temperature matches the target value of 36℃ and stabilizes. During the temperature stabilization period, keep the circulating fan at high speed to maintain the wet-bulb temperature difference between the upper and lower shelves within 0.5℃, maintain the opening of the cold air inlet and exhaust windows, and continue ventilation and dehumidification to maintain the target wet-bulb temperature of 36℃, promoting the drying of the middle and upper layers of leaves and the whitening of the midrib, preventing ash buildup, steaming, green veins, and re-greening. After stabilizing at 44℃ for 12 hours, the branch veins of the bottom layer of tobacco leaves will turn white and the tips will curl.

[0077] Step 7: Adjust airflow, stabilize wet-bulb temperature, and ensure the main veins of the tobacco leaves turn pale and the leaves are half-dry. After the veins of the bottom tobacco leaves turn white and the tips curl, maintain a temperature of 1℃ / 3h to raise the temperature to a stable dry-bulb temperature of 48℃. During the temperature rise, observe the inner wall of the observation window glass for moisture. Manually and gradually increase the opening of the cold air inlet until the wet-bulb temperature of the lower shed reaches 36℃ and the moisture on the inner wall of the observation window glass disappears. During the temperature stabilization period, maintain the opening of the cold air inlet and keep the wet-bulb temperature of the lower shed at 36℃. During the temperature rise and stabilization period, continue ventilation to remove moisture, maintaining the target wet-bulb temperature at 36℃. Keep all the leaves of the left and right dehumidification windows hanging, and keep the circulating fan at high speed to promote leaf drying, prevent dust accumulation, evaporation, and green veins, and promote the whitening of the main veins of the tobacco leaves, dryness of the leaves, and uniform and bright color. Baking at a stable temperature of 48℃ for 18h will result in the main veins of the bottom tobacco leaves turning pale and white, and the leaves being half-dry.

[0078] Step 8: Increase temperature and adjust ventilation, stabilize humidity in the lower shed, and ensure the main veins turn yellow and the leaves are completely dry. After the main veins of the bottom tobacco leaves turn from green to white and half of the leaves are dry, maintain a temperature of 1℃ / 2 hours to increase the temperature to a stable dry bulb temperature of 54℃. During the temperature increase, observe the inner wall of the observation window glass for moisture. Manually and gradually open the cold air inlet door to enhance ventilation and dehumidification, maintaining the wet bulb temperature in the lower shed at 36℃. During the temperature stabilization period, maintain the opening of the cold air inlet door and maintain the wet bulb temperature in the lower shed at 36℃. During the temperature increase and stabilization periods, continue ventilation and dehumidification, maintaining the target wet bulb temperature at 36℃. Keep all leaves of the left and right dehumidification windows hanging, and keep the circulating fan at high speed to promote the drying and color setting of the tobacco leaves, preventing scorching, green veins, and dark color. Baking at a stable temperature of 54℃ for 18 hours will result in the main veins of the bottom tobacco leaves turning yellow and the leaves being completely dry.

[0079] Step 9: Reduce humidity and ventilate at medium speed, allowing the midrib to partially dry. After the midribs of the bottom tobacco leaves turn yellow and the leaves are completely dry, maintain a temperature increase of 1℃ / h to a stable 60℃. Lower four leaves from the top of each of the left and right exhaust windows, manually close the cold air inlet damper to reduce ventilation and humidity removal, maintaining a wet-bulb temperature of 38℃. Adjust the circulating fan to medium speed to promote midrib drying and prevent the tobacco leaves from fading in color. Baking at a stable 60℃ for 10 hours will cause the midribs of the tobacco leaves to shrink and turn purple, indicating they are half-dry.

[0080] Step 10: Minimal dehumidification, minimal ventilation, low-speed circulation until the main vein is completely dry. After the main vein of the tobacco leaves shrinks and turns purple, and is half-dry, maintain a temperature increase of 1℃ / h to a stable temperature of 68℃. Lower all the blades of the left and right dehumidification windows, manually close the cold air inlet door slightly, leaving a small gap to reduce ventilation and dehumidification. Maintain the wet-bulb temperature at 40℃. Adjust the circulating fan to a low speed to promote the drying of the main vein, improve color, save fuel, prevent low-humidity tobacco leaves from becoming pale, and prevent high-humidity tobacco leaves from turning red. Stop the fire too early to allow the veins to heal. Maintain a stable temperature of 68℃ for 36 hours until the main vein of the bottom layer of tobacco leaves is completely dry and then stop the fire.

[0081] The following sections evaluate and analyze the tobacco leaves produced by the roasting method of this invention and the traditional roasting process from aspects such as tobacco leaf output value, appearance quality, and chemical composition.

[0082] Experimental results:

[0083] 1. Impact on tobacco production value

[0084] Compared with traditional baking technology, this invention increases the proportion of high-grade smoke by 5.08 percentage points, reduces the proportion of medium-grade smoke by 1.38 percentage points, increases the average price by 1.25 yuan / kg, and increases the output value by 2812.5 yuan / hm². 2 .

[0085] Table 4 Comparison of Tobacco Leaf Output Value

[0086] project Percentage of premium-grade tobacco (%) Percentage of moderate smokers (%) Average price (RMB / kg) <![CDATA[Output value (yuan / hm 2 )]]> invention 66.91 29.79 27.40 61650.0 Tradition 61.83 31.17 26.15 58837.50

[0087] 2. Impact on the appearance quality of tobacco leaves

[0088] The appearance of the tobacco leaves after curing according to this invention is superior to that of traditional curing technology in terms of leaf structure, maturity, quality, oil content, and color. The color index is better (uneven color and pale color are included in the color index), the yellow tobacco rate is increased by 3.4 percentage points, the mixed color tobacco rate (moldy, ash, and black residue are included in the mixed color rate) is reduced by 1.1 percentage points, and the green tobacco rate (floating green and green veins are included in the green tobacco rate) is reduced by 2.3 percentage points.

[0089] Table 5 Comparison of tobacco leaf appearance quality

[0090] project Blade structure Maturity identity Oil content Color Yellow smoke rate (%) Colored smoke rate (%) Green smoke rate (%) invention Still loose Mature Slightly thicker have medium and strong 97.3 1.6 1.1 Tradition Slightly dense Unripe, somewhat ripe, mature Thick, slightly thick Slightly, Yes middle 93.9 2.7 3.4

[0091] 3. Effects on the chemical composition of tobacco leaves

[0092] The tobacco leaves of this invention have higher total sugar and reducing sugar content and lower protein content after curing. Taking the upper leaves as an example, the total sugar content is 24.3% and the reducing sugar content is 12.8%, which are 8.8% and 4.4% higher than the traditional method, respectively. The protein content is 8.7%, which is 2.6% lower than the traditional method.

[0093] Table 6 Comparison of Chemical Components of Tobacco Leaves

[0094] project Total sugar (%) Reducing sugar (%) protein(%) invention 24.3 12.8 8.7 Tradition 15.5 8.4 11.3

[0095] 4. Evaluation of the tobacco curing effect

[0096] This invention can effectively improve the proportion of high-grade tobacco leaves, appearance quality, and chemical composition of tobacco leaves, thereby improving the industrial usability of tobacco leaves.

[0097] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for intensive baking, ventilation, and humidity control using biomass descending heating, characterized in that, Includes the following steps: The first step is to load the tobacco onto the kiln, close the doors and windows, set the baking process parameters, adjust the baking curve status indicator box to the initial position, adjust the circulating fan to the low speed setting, and start the baking process. The second step is to maintain the starting dry and wet bulb temperatures at 32℃ for 4 hours of curing. After preheating the tobacco leaves, increase the temperature by 1℃ / h to 36℃ for the dry bulb and 35℃ for the wet bulb, and maintain the temperature for 8-14 hours. If the inner wall of the observation window of the curing barn is damp, manually hang up two leaves at the bottom of each of the left and right exhaust windows of the curing barn to form symmetrical small exhaust vents to remove moisture from the lower part of the shed. The program automatically controls the opening of the cold air inlet door and keeps the circulating fan at a low speed until the tips of the top leaves turn yellow and soften. The third step is to raise the temperature at 1℃ / h to 38℃ for dry bulb and 35-37℃ for wet bulb, and bake at a stable temperature for 14-22 hours. Keep two leaves of each of the left and right dehumidification windows hanging up, and the program automatically controls the opening of the cold air inlet door. Keep the circulating fan at a low speed until the top layer of tobacco leaves turns yellow and softens in a coordinated manner, reaching 80% yellow and soft leaves. The fourth step is to adjust the circulating fan to medium speed and raise the temperature at 1℃ / 2h to 40℃ for dry bulb and 35-36℃ for wet bulb. Maintain the temperature for 12-16h. If the inner wall of the observation window glass becomes damp during this period, hang up four blades on each side of the dehumidification window to form two small dehumidification outlets on each side. The program will automatically control the opening of the cold air inlet door. Bake until the middle layer tobacco leaves are 80% yellow and the leaves are soft, and until the top layer leaves are yellow and the main veins are soft. Step 5: Increase the temperature by 1℃ / 2h to 42℃ for dry bulbs and 35-36℃ for wet bulbs, and maintain the temperature for 16-22h. Manually control the opening of the cold air inlet door to continuously ventilate and dehumidify, keep the wet bulb temperature of the lower shed at 35-36℃, and adjust the circulating fan to high speed to coordinate the yellowing and drying of the middle and upper layers, until the top layer of tobacco leaves reaches the point where the veins turn white and the tips curl, and the bottom layer reaches the point where the leaves are yellow with green veins and the main veins soften. Step 6: Increase the temperature to 44°C dry bulb temperature by 1°C / 2-3 hours, and stabilize the temperature for 8-12 hours. During the temperature increase, manually and gradually open the cold air inlet until the actual wet bulb temperature is consistent with the target value of 35-36°C and stabilizes. Continue ventilation to remove moisture and maintain the target wet bulb temperature of 35-37°C. Keep the circulating fan at high speed. Bake until the veins of the bottom tobacco leaves turn white and the tips curl. Step 7: Increase the temperature to 48°C dry bulb temperature by 1°C / 2-3 hours and stabilize the temperature for 12-18 hours. During the temperature increase and stabilization, continue to ventilate and dehumidify to maintain the target wet bulb temperature of 35-36°C. Keep all the leaves of the left and right dehumidification windows hanging up and use the high speed setting of the circulating fan to bake until the main vein of the bottom tobacco leaves turns from green to white and the leaves are half dry. Step 8: Increase the temperature at 1℃ / 2h to 54℃ dry bulb temperature and stabilize it for 10-18h. During the temperature increase and stabilization, manually and gradually open the cold air inlet until the actual wet bulb temperature value is consistent with the target value and stabilizes. Continue ventilation and dehumidification to maintain the target wet bulb temperature of 35-37℃. Keep the circulating fan running at high speed and keep all leaves of the left and right dehumidification windows hanging up. Bake until the main vein of the bottom tobacco leaves turns yellow and the leaves are completely dry. Step 9: Increase the temperature to 60℃ at 1℃ / h and stabilize it for 6-10 hours. Lower the four blades at the bottom of each of the left and right exhaust windows, manually close the cold air inlet door to reduce ventilation and dehumidification, maintain the wet bulb temperature at 37-39℃, adjust the circulating fan to medium speed, and bake until the main vein of the tobacco leaves shrinks and turns purple, and it is half dry. Step 10: Increase the temperature to 65-68℃ at a rate of 1℃ / h and maintain the temperature for 24-36 hours. Lower all the blades of the left and right exhaust windows, manually close the cold air inlet door, leaving a gap to reduce ventilation and dehumidification. Keep the wet bulb temperature at 38-40℃, adjust the circulating fan to low speed, and bake until the main veins of the top layer of tobacco leaves are completely dry before stopping the fire.

2. The biomass descending intensive baking, ventilation, and humidity control method according to claim 1, characterized in that, In the first step, the tobacco leaves used in the same kiln are of the same variety and have the same maturity level. They are then packed into high, medium, and low temperature layers according to their maturity level, with the top layer being denser and the bottom layer sparser, ensuring that the packing is full and even.

3. The biomass descending intensive baking, ventilation, and humidity control method according to claim 1, characterized in that, In the first step, the baking process parameters are ten target dry-bulb stable temperature points. The first stable temperature point has a dry-bulb temperature of 32℃ and a wet-bulb temperature of 32℃, with a stabilization time of 4 hours and a heating time of 4 hours. The second stable temperature point has a dry-bulb temperature of 36℃ and a wet-bulb temperature of 35℃, with a stabilization time of 4-10 hours and a heating time of 2 hours. The third stable temperature point has a dry-bulb temperature of 38℃ and a wet-bulb temperature of 35-36℃, with a stabilization time of 12-20 hours and a heating time of 4 hours. The fourth stable temperature point has a dry-bulb temperature of 40℃ and a wet-bulb temperature of 35-36℃, with a stabilization time of 8-12 hours and a heating time of 4 hours. The fifth stable temperature point has a dry-bulb temperature of 42℃ and a wet-bulb temperature of 35-36℃, with a stabilization time of 12-18 hours and a heating time of 4 hours. The temperature fluctuations were as follows: 4-6 hours for the sixth stable temperature point; dry bulb temperature 44℃; wet bulb temperature 35-36℃; stable temperature for 8-12 hours; heating time 8-12 hours for the seventh stable temperature point; dry bulb temperature 48℃; wet bulb temperature 35-36℃; stable temperature for 12-18 hours; heating time 12 hours for the eighth stable temperature point; dry bulb temperature 54℃; wet bulb temperature 35-36℃; stable temperature for 10-18 hours; heating time 6 hours for the ninth stable temperature point; dry bulb temperature 60℃; wet bulb temperature 37-39℃; stable temperature for 6-10 hours; heating time 5-8 hours for the tenth stable temperature point; dry bulb temperature 65-68℃; wet bulb temperature 38-40℃; stable temperature for 24-36 hours.

4. The biomass descending intensive baking, ventilation, and humidity control method according to claim 1, characterized in that, The circulating fan has a low speed setting of 720 r / min, a medium speed setting of 960 r / min, and a high speed setting of 1440 r / min.

5. The biomass descending intensive baking, ventilation, and humidity control method according to claim 1, characterized in that, In the fifth step, if the wet-bulb temperature difference between the upper and lower greenhouses exceeds 0.5℃ during the temperature stabilization period, hang up six leaves on the upper part of each of the left and right exhaust windows to form three small exhaust vents on each side, maintaining the humidity difference between the upper and lower greenhouses within 0.5℃.

6. The biomass descending intensive baking, ventilation, and humidity control method according to claim 1, characterized in that, In step six, if the inner wall of the observation window becomes damp during the heating process, hang up all the blades of the left and right dehumidification windows to keep the wet-bulb humidity difference between the upper and lower sheds within 0.5℃.

7. The biomass descending intensive baking, ventilation, and humidity control method according to claim 1, characterized in that, In steps seven and eight, if the inner wall of the observation window glass becomes damp during the heating process, manually open the cold air intake door until the wet-bulb temperature of the lower ceiling reaches 35-36℃ and the moisture on the inner wall of the observation window glass disappears.

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