Process for softening tobacco leaves at upper part of descending type bulk curing barn

Abstract

The invention discloses a descending type bulk curing barn upper portion tobacco leaf softening technology which comprises the steps of facility preparation before curing, tobacco leaf preparation, upper-dense lower-thin kang loading, parameter setting for curing, yellowing early stage, slight humidity reduction, tip yellowing, yellowing middle stage, smoke observation humidity reduction, full-yellow full-softening, yellowing later stage, window observation humidity reduction, small rib half-white, large rib full-softening, yellowing later stage and window observation humidity elimination. Small tendons are all white, pointed and hemmed, color fixing early stage, window view moisture removal, large tendons are all white, small tendons are half-dried, color fixing later stage, proper moisture rising, small tendons are all dried, color difference is reduced, tendons are dried early stage, moisture rising and stabilizing are carried out, the large tendons are shrunk and become purple by half, and temperature and humidity are stabilized and all the large tendons are shrunk and purple in the later stage. The method is high in operability, the problems of mildewing, baking blackening, baking stiffness, baking green and the like in the tobacco leaf baking process can be reduced, the appearance quality of the tobacco leaves is improved, chemical components are more coordinated, and the output value and usability of the tobacco leaves are improved.

Description

Technical Field

[0001] The invention relates to a process for softening tobacco leaves in the upper part of a descending intensive curing barn, and belongs to the technical field of tobacco leaf curing. Background Art

[0002] Tobacco leaf curing is the most important link affecting tobacco leaf quality, yield and availability, and is also the main factor affecting tobacco farmers' economic income, cigarette product quality and economic benefits. The formation of tobacco leaf quality, use value and economic value is jointly determined by field production management and scientific curing. It can be seen that curing is important in tobacco leaf quality and flue-cured tobacco production. The curing characteristics of flue-cured tobacco leaves are closely related to the curing process and curing quality, which is the basic basis for formulating appropriate curing methods for tobacco leaves and creating the best curing conditions in order to produce the best quality tobacco leaves.

[0003] At present, in the process of baking tobacco leaves in the upper part of the descending intensive baking barn, some tobacco areas still adopt the traditional baking technology of moisturizing and yellowing, large ventilation and large dehumidification. The specific process is:

[0004] The first step is to load the smoke into the kang, close the doors and windows, set the baking curve parameters, adjust the baking curve status indicator box to the initial position, set the circulating fan to high speed, and ignite the baking.

[0005] The second step is to maintain the starting dry-bulb temperature at 32°C for 8-12 hours after ignition. The program automatically controls the opening of the cold air inlet door and the circulating fan maintains a high gear. After preheating for 4 hours, the dry-bulb temperature is increased to 36°C and baked at a steady temperature for 18-24 hours until the upper tobacco leaves sweat and the tips turn yellow.

[0006] The third step is to keep the circulating fan at high gear and control the opening of the cold air inlet door through a program. Raise the dry bulb to 38°C and the wet bulb to 37-38°C in 4 hours. Bake at a steady temperature for 24-36 hours until the lower leaves are completely yellow and not soft or swollen.

[0007] The fourth step is to keep the circulating fan running at high speed, program-control the opening of the cold air inlet door, raise the dry bulb to 40℃ and the wet bulb to 34-35℃ in 8 hours, and bake at a steady temperature for 12-18 hours until the small veins of the lower layer of tobacco leaves are half white and the leaves are half soft.

[0008] The fifth step is to manually open the cold air inlet door to the maximum, maintain the maximum ventilation volume, keep the circulating fan running at high speed, raise the dry bulb to 42℃ and the wet bulb to 28-30℃ in 8 hours, and bake at a steady temperature for 16-24 hours until the tobacco leaves on the lower layer are green and half dry.

[0009] The sixth step is to keep the cold air inlet door open at the maximum, continue to ventilate and dehumidify, run the circulating fan at high speed, raise the dry bulb to 44°C in 8 hours, maintain a stable temperature for 12-18 hours, and keep the wet bulb at 28-30°C, and bake until the large tendons of the lower tobacco leaves are half white and the small tendons are half dry.

[0010] The seventh step is to keep the cold air inlet door open at the maximum, continue to ventilate and dehumidify, raise the dry bulb to 48°C in 8 hours, bake at a steady temperature for 12-18 hours, with the wet bulb at 30-32°C, and run the circulating fan at high speed until the large veins of the lower layer of tobacco leaves are slightly green and the small veins are completely dry.

[0011] The eighth step is to keep the cold air inlet door open at the maximum, continue to ventilate and dehumidify, raise the dry bulb to 54°C in 6 hours, bake at a steady temperature for 8-16 hours, with the wet bulb at 30-32°C, and run the circulating fan at high speed until the large tendons of the lower layer of tobacco leaves shrink.

[0012] The ninth step is to keep the cold air inlet door open at maximum, continue to ventilate and dehumidify, raise the dry bulb to 60℃ for 6 hours and keep the temperature steady for 6-12 hours, wet bulb at 32-34℃, run the circulating fan at high speed, and bake until the tobacco leaves shrink and turn half purple.

[0013] The tenth step is to keep the cold air inlet door open at the maximum, continue to ventilate and dehumidify, raise the dry bulb to 68℃ in 8 hours, bake at a steady temperature for 16-24 hours, with the wet bulb at 32-34℃, and run the circulating fan at high speed until the large veins of the lower layer of tobacco leaves have all shrunk and turned purple.

[0014] However, for the upper tobacco leaves, traditional baking technology is prone to problems such as mildew, ash, blackening, floating green, blue veins, stiffness, poor oil content, and uneven color. In particular, the problems of green and mixed, stiffness, and poor oil content in tobacco leaves are more prominent, and it is necessary to improve this. Summary of the invention

[0015] Based on the above, the present invention provides a process for softening the upper tobacco leaves in a descending intensive curing barn. The process is suitable for the tobacco baking process and can solve the problems of tobacco mildew, dust hanging, blackening, floating green, blue veins, uneven color, poor oil content, etc. that occur when the upper tobacco leaves use traditional descending intensive baking technology, so as to improve the tobacco baking quality.

[0016] The technical solution of the present invention is: a process for softening tobacco leaves in the upper part of a descending intensive curing barn, comprising the following steps:

[0017] The first step is to load the smoke with dense smoke at the top and thin smoke at the bottom, close the doors and windows, set the baking process parameters, adjust the baking curve status indicator box to the initial position, start the circulating fan at low speed, and ignite the baking;

[0018] The second step is to maintain the starting target dry-bulb and wet-bulb temperature at 32℃ for 12-18h. After the tobacco leaves are preheated, the dry-bulb temperature is raised to 36℃ for 4h and the wet-bulb temperature is raised to 35-34℃ for 18-24h. The program automatically controls the opening of the cold air inlet door, and the circulating fan is kept at a low speed. The tobacco leaves on the upper layer are baked until the tip turns yellow. It is observed that there is water mist on the inner wall of the window glass and the tobacco leaves are sweating.

[0019] Step 3: Raise the dry bulb to 38℃ and the wet bulb to 36℃ for 4 hours, bake until the upper tobacco leaves turn 80% yellow and become soft, adjust the wet bulb to 35℃, bake until the middle tobacco leaves turn 80% yellow and become soft, adjust the wet bulb to 34℃, bake until the lower tobacco leaves turn 80% yellow and become soft, keep the wet bulb at 34℃, bake until the lower tobacco leaves turn completely yellow and become soft, and keep the wet bulb temperature at more than 6 hours when the wet bulb temperature is lowered by 1℃; bake at a steady temperature of 38℃ for 24-36 hours. After the tip of the upper tobacco leaves turns yellow, observe the water mist on the inner wall of the window glass, hang two leaves of the left and right dehumidification windows, control the opening of the cold air inlet door with a program, and adjust the circulating fan to high gear;

[0020] Step 4: If the inner wall of the window glass is still foggy, hang up all the blades of the left and right dehumidification windows, keep the circulating fan running at high speed, program the opening of the cold air inlet door, place a small wooden block at the lower end of the cold air inlet door frame, do not close the door tightly, and keep the ventilation smooth; raise the dry bulb temperature to 40℃ and the wet bulb temperature to 34℃ for 8 hours and bake for about 6 hours. If the inner wall of the window glass is still foggy, reduce the wet bulb temperature by 1℃ every 6 hours, and the wet bulb temperature can be below 31℃ until the fog disappears and no longer be reduced. Bake at a steady temperature of 40℃ for 12-18 hours until the small tendons of the lower tobacco leaves are half white and the large tendons are completely soft;

[0021] Step 5: Keep all blades of the left and right dehumidification windows up, keep the circulating fan running at high speed, program-control the opening of the cold air inlet door, keep a small wooden block at the bottom of the cold air inlet door frame to keep ventilation smooth; raise the dry bulb to 42℃ for 8 hours and the wet bulb to 32℃ for about 6 hours. If fog is observed on the inner wall of the window glass, reduce the wet bulb temperature by 1℃ every 6 hours. The wet bulb temperature can be below 30℃ until the fog disappears and no longer be reduced. Bake at a steady temperature of 42℃ for 12-18 hours until the small tendons of the lower tobacco leaves are completely white and the hook tips are curled;

[0022] Step 6: Keep all blades of the left and right dehumidification windows up, keep the circulating fan running at high speed, program-control the opening of the cold air inlet door, keep a small wooden block at the bottom of the cold air inlet door frame to keep ventilation unobstructed; raise the dry bulb to 44℃ and the wet bulb to 32℃ for 8 hours and bake for about 6 hours. If fog is observed on the inner wall of the window glass, reduce the wet bulb temperature by 1℃ every 6 hours or so, and the wet bulb temperature can be below 30℃ until the fog disappears and no longer be reduced. Bake at a steady temperature of 44℃ for 12-18 hours until the large tendons of the lower tobacco leaves are completely white and the small tendons are half dry;

[0023] Step 7: Keep all blades of the left and right dehumidification windows up, keep the circulating fan running at high speed, program-control the opening of the cold air inlet door, keep a small wooden block at the bottom of the cold air inlet door frame to keep ventilation smooth; raise the dry bulb to 48℃ and the wet bulb to 34℃ for 8 hours and bake for about 6 hours. If the inner wall of the window glass is foggy, lower the wet bulb temperature by 1℃. Every 6 hours of baking, lower the wet bulb temperature by 1℃. The wet bulb temperature can be below 32℃ until the fog disappears and no longer be lowered. Bake at a steady temperature of 48℃ for 10-16 hours until the large tendons of the lower tobacco leaves are completely yellow and the base of the small tendons is not dry;

[0024] Step 8: Keep all blades of the left and right dehumidification windows hung up, keep the circulating fan running at high speed, program-control the opening of the cold air inlet door, keep a small wooden block at the bottom of the cold air inlet door frame to keep ventilation smooth; raise the dry bulb to 54℃ and the wet bulb to 36℃ for 9 hours and bake for about 6 hours. If the inner wall of the window glass is foggy, lower the wet bulb temperature by 1℃. Every 6 hours of baking, lower the wet bulb temperature by 1℃. The wet bulb temperature can be below 34℃ until the fog disappears and no longer lowered. Bake at a steady temperature of 54℃ for 12-18 hours until the small tendons in the lower layer are completely dry and the color difference between the front and back of the tobacco leaves becomes smaller;

[0025] The ninth step is to close all the blades of the dehumidification window, adjust the circulating fan to run at a low speed, program the opening of the cold air inlet door, and remove the small wooden block at the bottom of the cold air inlet door frame; raise the dry bulb to 60℃ and the wet bulb to 38℃ for 6 hours, and bake at a steady temperature for 8-12 hours until the tobacco leaves on the lower layer shrink and turn half purple;

[0026] The tenth step is to control the opening of the cold air inlet door and the moisture exhaust port through the program to keep the circulating fan running at a low speed; raise the dry bulb to 68°C and the wet bulb to 39°C in 8 hours, and bake at a steady temperature for 16-24 hours until the large veins of the lower layer of tobacco leaves have all shrunk, turned purple and hardened.

[0027] Preferably, in the first step, the tobacco leaves on the same kang are of the same variety and have the same maturity level. They are loaded in upper, middle and lower layers according to their high, medium and low maturity levels, with the upper layer being dense and the lower layer being sparse, so that the tobacco leaves are filled and evenly loaded.

[0028] Preferably, in the first step, the baking process parameters are ten target dry-bulb stable temperature points, the first stable temperature point dry-bulb temperature is 32°C, the wet-bulb temperature is 32°C, the stable temperature is 12-18h, the second stable temperature point dry-bulb temperature is 36°C, the wet-bulb temperature is 35-34°C, the stable temperature is 18-24h, and the heating time is 4h, the third stable temperature point dry-bulb temperature is 38°C, the wet-bulb temperature is 36-34°C, the stable temperature is 24-36h, and the heating time is 4h, the fourth stable temperature point dry-bulb temperature is 40°C, the wet-bulb temperature is 34-31°C, the stable temperature is 12-18h, and the heating time is 8h, the fifth stable temperature point dry-bulb temperature is 42°C, the wet-bulb temperature is 32-30°C, and the stable temperature is 12-18h, heating time 8h, the sixth stable temperature point dry bulb temperature 44℃, wet bulb temperature 32-30℃, stable temperature 12-18h, heating time 8h, the seventh stable temperature point dry bulb temperature 48℃, wet bulb temperature 34-32℃, stable temperature 10-16h, heating time 8h, the eighth stable temperature point dry bulb temperature 54℃, wet bulb temperature 36-34℃, stable temperature 12-18h, heating time 9h, the ninth stable temperature point dry bulb temperature 60℃, wet bulb temperature 38℃, stable temperature 8-12h, heating time 6h, the tenth stable temperature point dry bulb temperature 68℃, wet bulb temperature 39℃, stable temperature 16-24h, heating time 8h

[0029] Preferably, the rotation speed of the circulating fan corresponding to the low speed gear is 720r / min, and the rotation speed corresponding to the high speed gear is 1440r / min.

[0030] The applicant has found that during the intensive baking of the upper tobacco leaves, the traditional baking technology of excessive moisturizing and yellowing, large ventilation and large moisture removal for color fixing and drying mainly has the following problems: in the middle stage of yellowing, the dry bulb temperature is 38℃, the wet bulb temperature is 37.5-37℃, the humidity is high, the ventilation and moisture removal capacity is small, the leaves are baked until they are completely yellow, not soft and swollen, the leaves are completely yellow, not fully softened, and the tobacco leaves are easy to bake black, stiff, and moldy; in the late stage of yellowing, the dry bulb temperature is 40℃, the wet bulb temperature is 36-35℃, the ventilation and moisture removal capacity is small, the small tendons of the tobacco leaves are half white, the leaves are half soft, the tobacco leaves are not softened enough, and they are easy to bake black and stiff; in the late stage of yellowing, the dry bulb temperature is 42℃, the wet bulb temperature is 30-28℃, large ventilation and moisture removal are used, the tobacco leaves are baked until the large tendons are green and the leaves are half dry, the humidity drops too much, and the tobacco leaves are dried too quickly. Tobacco leaves are easy to be roasted black, stiff or green; in the early stage of color fixing, the dry-bulb temperature is 44℃, the wet-bulb temperature is 30-28℃, and the ventilation and moisture removal are carried out continuously. The tobacco leaves are roasted until the large tendons are half white and the small tendons are half dry. The dry-bulb temperature is 48℃, the wet-bulb temperature is 32-30℃, and the ventilation and moisture removal are carried out continuously. The large tendons of the tobacco leaves are slightly green and the small tendons are completely dry. If the tobacco leaves dry too fast, the tendons will not have time to turn white, and green tobacco is easy to be roasted; in the late stage of color fixing, the dry-bulb temperature is 54℃, the wet-bulb temperature is 32-30℃, and the ventilation and moisture removal are carried out continuously. The tobacco leaves are roasted until the large tendons shrink and the leaves are dry. The humidity is too low and the color difference between the front and back of the leaves is large; in the tendon drying stage, the dry-bulb temperature is 60-68℃, the wet-bulb temperature is 32-34℃, and the ventilation and moisture removal are carried out continuously. The tobacco leaves are roasted until the large tendons shrink and turn purple and dry. The humidity is too low and the oil content of the tobacco leaves is poor.

[0031] The beneficial effects of the present invention are as follows: in order to solve the problems of mildew, stiffness, blackening, greening, large color difference and poor oil content in the upper tobacco leaves after being roasted using traditional roasting technology, the present invention adopts measures such as segmented dehumidification and softening, adjusting the opening of the cold air inlet door and the dehumidification window blades, adjusting the fan speed, etc. according to the tobacco loading density and the changes in the roasting process. According to the applicant's tests, the problems of mildew, stiffness, blackening, greening, large color difference and poor oil content in the upper tobacco leaves during descending intensive roasting can be reduced, especially the problems of stiffness, blackening and greening of tobacco leaves are solved, thereby improving the roasting quality of tobacco leaves. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation of the present invention is described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0033] First, the curing room is explained. The existing descending intensive curing room includes a heating room and a smoke loading room. An observation window is installed on the side of the smoke loading room close to the heating room, and a cold air inlet door is opened at the lower part of one side of the heating room. The opening of the cold air inlet door can be automatically controlled by the baking program or manually controlled. Dehumidification window blades are installed at the lower part of both sides of the smoke loading room close to the heating room, and each side of the dehumidification window blade has eight blades. The speed corresponding to the low speed gear of the circulating fan in the curing room is 720r / min, and the speed corresponding to the high speed gear is 1440r / min.

[0034] The process for softening tobacco leaves in the upper part of a descending intensive curing barn of the present invention comprises the following steps:

[0035] The first step is to prepare the facilities and tobacco leaves before baking. Before installing the kang, remove the dust from the heating equipment to prevent blockage, seal the enclosure structure of the baking room to prevent air leakage, seal the heating equipment to prevent smoke leakage, and ensure that the equipment can work normally after powering on; pick the tobacco leaves according to the current maturity harvesting standards, classify and clip them, and install the sensors in place.

[0036] In this step, the upper tobacco leaves are harvested when they are mainly yellow with green in the middle; they are classified and woven (clipped), and the parts and maturity of tobacco leaves on the same rod (clip) are basically the same, there are about 60 clips per rod, 2-3 leaves in each clip, the number of tobacco leaves in each clip is the same, and the clips are full and even, which has the effect of making the changes of tobacco leaves on the same rod (clip) basically the same; the sensor is installed in place, the kettle is filled with clean water, the absorbent cotton yarn is clean, the upper end is wrapped with the wet-bulb thermometer sensing bulb, and the lower end is all placed in the kettle, and the temperature and humidity sensors are installed at the corresponding positions of the bottom shed and the ceiling respectively.

[0037] The second step is to load the tobacco leaves densely on the top and sparsely on the bottom, and set the parameters for baking. The tobacco leaves are loaded in the upper, middle and lower layers of the baking room according to their maturity, densely on the top and sparsely on the bottom, and the number of clips (rods) is reduced by 8 from top to bottom to avoid excessive humidity in the middle and lower layers, which will cause the tobacco leaves to not soften sufficiently and become stiff after baking. Each layer should be filled and evenly loaded, and there should be 4 layers, with a total of about 400 clips (rods). After the installation of the tobacco leaves, close the doors and windows, and after the electrical equipment is powered on, the left side of the dry bulb temperature display box on the automatic controller display screen is set to "upper shed". According to the current baking process, ten target dry bulb temperature stabilization points are set. Combined with the baking characteristics of the upper tobacco leaves and the density of tobacco loading, the corresponding target wet bulb temperature, stabilization time, heating time and other parameters are set. The baking plan parameters are set as shown in Table 1. After the parameters are set, adjust the status indicator box to the initial position, turn on the low speed gear of the circulating fan, and ignite for baking.

[0038] Baking scheme parameter table 1

[0039]

[0040] In this step, the left side of the dry bulb temperature display box is set to "upper shed", and the actual temperature and humidity values ​​of the upper shed tobacco leaves are displayed during baking; the baking parameters are set to avoid large fluctuations in the baking temperature and humidity environment, which affects the quality of tobacco leaves. The parameter value characteristics are that ten stable temperature points are set when igniting, and the wet bulb temperature and stable temperature time are set to the upper limit value. The initial wet bulb temperature of the stable temperature point during the baking process takes the upper limit value. The wet bulb temperature is reduced in stages according to the tobacco leaf change stage target and the water mist index of the observation window. After the stage target index is reached, it will no longer be reduced. The baking time can be long or short to achieve the tobacco leaf change target at the stable temperature point. Adjust the baking curve status indicator box to the initial position, which is to avoid the indicator box in other positions, the ignition temperature is high, and the tobacco leaves are baked green; adjust the circulating fan to a low speed gear, which is to properly moisturize and yellow the tobacco leaves during baking to avoid premature water loss.

[0041] The third step is to reduce humidity slightly before yellowing, and the tip turns yellow. Keep the starting target dry-bulb and wet-bulb temperature at 32℃ for 12-18h. After the tobacco leaves are preheated, raise the dry-bulb temperature to 36℃ for 4h and the wet-bulb temperature to 35-34℃ for 18-24h. Reduce humidity appropriately to prevent the tobacco leaves from getting moldy. The program automatically controls the opening of the cold air inlet door, and the circulating fan is kept at a low speed. Bake until the tip of the upper tobacco leaves turns yellow. Observe the water mist on the inner wall of the window glass and the tobacco leaves sweat.

[0042] The fourth step is to reduce humidity in the middle of yellowing, and observe the tobacco to reduce humidity, and make it completely yellow and soft. After the tip of the upper tobacco leaves turns yellow, raise the dry bulb to 38℃ and the wet bulb to 36℃ for 4 hours, bake until the upper tobacco leaves turn 80% yellow and the leaves are soft, adjust the wet bulb to 35℃, bake until the middle tobacco leaves turn 80% yellow and the leaves are soft, adjust the wet bulb to 34℃, bake until the lower tobacco leaves turn 80% yellow and the leaves are soft, keep the wet bulb to 34℃, bake until the lower tobacco leaves are completely yellow and soft, and collect the strips. The wet bulb temperature is lowered by 1℃ for more than 6 hours to avoid excessive yellowing of the tobacco leaves, insufficient water loss, and stiff and non-soft tobacco leaves after baking. Bake at a steady temperature of 38℃ for 24-36 hours. After the tip of the upper tobacco leaves turns yellow, observe the water mist on the inner wall of the window glass, hang two leaves of the left and right dehumidification windows, program the opening of the cold air inlet door, and adjust the circulating fan to high speed to prevent tobacco leaves from mildewing.

[0043] Step 5. In the late stage of yellowing, check the window to reduce humidity, small tendons are half white, and large tendons are completely soft. After the lower layer of tobacco leaves are completely yellow, if the inner wall of the window glass is observed to be foggy, hang up all the blades of the left and right dehumidification windows, keep the circulating fan running at high speed, program the opening of the cold air inlet door, place a small wooden block at the lower end of the cold air inlet door frame, do not close the damper, keep the ventilation smooth, and avoid the tobacco leaves from being baked black. Raise the dry bulb to 40℃ for 8 hours and the wet bulb to 34℃ for about 6 hours. If there is still fog on the inner wall of the window glass, lower the wet bulb temperature by 1℃ every 6 hours, and the bulb temperature can be below 31℃ until the fog disappears and no longer lowered. Bake at a steady temperature of 40℃ for 12-18 hours until the small tendons of the lower layer of tobacco leaves are half white and the large tendons are completely soft, to avoid the humidity in the baking room not being enough to soften the large tendons and bake them black and stiff.

[0044] Step 6. In the late stage of yellowing, check the window for moisture removal, small tendons are completely white, and the hook tip curls. After the small tendons of the lower tobacco leaves are half white and the large tendons are completely soft, keep all the leaves of the left and right moisture removal windows hung up, keep the circulating fan running at high speed, program the opening of the cold air inlet door, and place a small wooden block at the bottom of the cold air inlet door frame to keep ventilation smooth and prevent the tobacco leaves from turning black. Raise the dry bulb to 42℃ for 8 hours and the wet bulb to 32℃ for about 6 hours. If the inner wall of the window glass is observed to be foggy, the wet bulb temperature is lowered by 1℃ every 6 hours or so. The wet bulb temperature can be below 30℃ until the fog disappears and no longer lowered. Bake at a steady temperature of 42℃ for 12-18 hours until the small tendons of the lower tobacco leaves are completely white and the hook tip curls, to avoid insufficient whitening of the small tendons and blue tendons after baking.

[0045] Step 7: In the early stage of color fixing, check the window for moisture removal, the big tendons are completely white, and the small tendons are half dry. The small tendons of the lower tobacco leaves are completely white, and after the hook tip is curled, keep all the leaves of the left and right moisture removal windows hung up, keep the circulating fan running at high speed, program the opening of the cold air inlet door, keep a small wooden block at the bottom of the cold air inlet door frame, keep ventilation unobstructed, and prevent the tobacco leaves from turning black. Raise the dry bulb to 44℃ for 8 hours and the wet bulb to 32℃ for about 6 hours. If the inner wall of the window glass is observed to be foggy, the wet bulb temperature is lowered by 1℃ every 6 hours. The wet bulb temperature can be below 30℃ until the fog disappears and no longer lowered. Bake at a steady temperature of 44℃ for 12-18 hours until the big tendons of the lower tobacco leaves are completely white and the small tendons are half dry. Avoid baking black due to excessive humidity, and baking green and stiffness due to excessive humidity.

[0046] Step 8. In the early stage of color fixation, check the window for moisture removal, the big tendons are all yellow, and the base of the small tendons is not dry. When the big tendons of the lower tobacco leaves are all white and the small tendons are half dry, keep all the leaves of the left and right moisture removal windows hung up, keep the circulating fan running at high speed, program the opening of the cold air inlet door, keep a small wooden block at the bottom of the cold air inlet door frame, keep ventilation smooth, and prevent the tobacco leaves from turning black. Raise the dry bulb to 48℃ for 8 hours and the wet bulb to 34℃ for about 6 hours. If the inner wall of the window glass is foggy, lower the wet bulb temperature by 1℃. Every 6 hours of baking, lower the wet bulb temperature by 1℃. The wet bulb temperature can be below 32℃ until the fog disappears and no longer lowered. Bake at a steady temperature of 48℃ for 10-16 hours until the big tendons of the lower tobacco leaves are all yellow and the base of the small tendons is not dry. Avoid excessive humidity and variegated tobacco leaves, and avoid baking green and stiffness due to low humidity.

[0047] The ninth step is to properly increase humidity in the late stage of color fixation, so that the small tendons are completely dry and the color difference becomes smaller. After the large tendons of the lower tobacco leaves are completely yellow, keep all the leaves of the left and right dehumidification windows hung up, keep the circulating fan running at high speed, program the cold air inlet door opening, keep a small wooden block at the bottom of the cold air inlet door frame, keep ventilation smooth, and prevent the tobacco leaves from turning darker. Raise the dry bulb to 54℃ and the wet bulb to 36℃ for 9 hours and bake for about 6 hours. If the inner wall of the window glass is foggy, the wet bulb temperature is lowered by 1℃. Every 6 hours of baking, the wet bulb temperature is lowered by 1℃. The wet bulb temperature can be below 34℃ until the fog disappears and no longer lowered. Bake at a steady temperature of 54℃ for 12-18 hours until the small tendons of the lower layer are completely dry and the color difference of the front and back of the tobacco leaves is reduced. Avoid excessive humidity and the inner leaves are not dry and baked with mixed colors.

[0048] Step 10: In the early stage of drying, the humidity is raised and stabilized, and the large tendons shrink and turn half purple. After the small tendons in the lower layer are completely dry, close all the leaves of the dehumidification window, adjust the circulating fan to run at a low speed, program the opening of the cold air inlet door, and remove the small wooden block at the bottom of the cold air inlet door frame. Raise the dry bulb to 60℃ and the wet bulb to 38℃ for 6 hours, and bake at a stable temperature for 8-12 hours until the large tendons in the lower layer of tobacco leaves shrink and turn half purple, avoiding baking red due to excessive humidity and poor oil content due to low humidity.

[0049] Step 11: In the late stage of drying, stabilize the temperature and humidity, and all the big tendons will shrink and turn purple. After the big tendons of the lower tobacco leaves shrink and turn purple by half, the program controls the opening of the cold air inlet door and the dehumidification port, and keeps the circulating fan running at a low speed. Raise the dry bulb to 68℃ and the wet bulb to 39℃ for 8 hours, and bake at a stable temperature for 16-24 hours until the big tendons of the lower tobacco leaves shrink, turn purple and harden. Avoid excessive temperature and humidity to bake the tobacco leaves red, drastically reduce the temperature to soak the tendons and leaves, and too low humidity to cause poor oil content in the tobacco leaves.

[0050] The baking effect of the present invention is tested and verified below:

[0051] The experiment was conducted in Liupanshui City, Guizhou Province in 2024. The test flue-cured tobacco variety was Yunyan 87, and the upper tobacco leaves were used as test materials. The test tobacco leaves were cultivated and managed in accordance with the standardized production of local high-quality tobacco leaves, and were harvested at maturity according to the tobacco leaf maturity standards and processes. The test flue-curing room was a descending intensive flue-curing room. The traditional baking technology was used as a control, and the baking process of the present invention was used as a treatment, and comparative tests were carried out at the same time. Except for the process conditions and the number of tobacco loaded on each layer, other factors such as the structure of the flue-curing room and the tobacco leaf variety were the same.

[0052] Traditional baking process:

[0053] The first step is to load the tobacco and set the parameters. Load the tobacco in the upper, middle and lower layers of the baking room according to the maturity, high, medium and low, from top to bottom, with 100 clips of tobacco per layer, fill them up and load them evenly, load 4 layers, a total of 400 clips. Set the baking program parameters, as shown in Table 2 below. After the parameters are set, adjust the status indicator box to the initial position, set the circulating fan to high speed, and ignite the baking.

[0054] Table 2 Baking scheme parameters

[0055]

[0056] The second step is the early stage of yellowing. The temperature and humidity are synchronized, the tobacco leaves sweat, and the tips turn yellow. After ignition, the starting dry-bulb temperature is maintained at 32°C for 12 hours. The program automatically controls the opening of the cold air inlet door, and the circulating fan is kept at high speed to adapt to the tobacco leaf baking environment. After preheating for 4 hours, the dry-bulb temperature is raised to 36°C, and the temperature is kept stable for 20 hours. The upper tobacco leaves sweat and the tips turn yellow.

[0057] The third step is the middle stage of yellowing, moisturizing and yellowing, the leaves are completely yellow, not soft or hard. After the tip of the upper tobacco leaves turns yellow, the circulating fan is kept at high speed, the program controls the opening of the cold air inlet door, the dry bulb is raised to 38℃ for 4 hours, the wet bulb is 37℃, and the temperature is kept constant for 30 hours until the lower leaves are completely yellow, not soft or hard.

[0058] Step 4: In the late yellowing stage, the humidity is reduced and discharged quickly, the small ribs are half white, and the leaves are half soft. After the lower leaves are completely yellow, keep the circulating fan running at high speed, program the cold air inlet door opening, raise the dry bulb to 40℃ and the wet bulb to 35℃ in 8 hours, and bake at a constant temperature for 12 hours until the small ribs of the lower tobacco leaves are half white and the leaves are half soft.

[0059] Step 5: In the late yellowing stage, the humidity is reduced and the leaves are half-dried. When the lower tobacco leaves have half-white leaves and half-soft leaves, manually open the cold air inlet door to the maximum, maintain the maximum ventilation, keep the circulating fan running at high speed, raise the dry bulb to 42℃ and the wet bulb to 30℃ for 8 hours, and bake at a constant temperature for 20 hours until the lower tobacco leaves have green leaves and half-dried leaves.

[0060] Step 6: In the early stage of color fixation, continue to ventilate vigorously until the big veins are half white and the small veins are half dry. When the big veins of the lower tobacco leaves are green and the leaves are half dry, keep the cold air inlet door open at the maximum, continue to ventilate and dehumidify, and run the circulating fan at high speed; raise the dry bulb to 44℃ for 8 hours, keep the temperature stable for 16 hours, and the wet bulb is 30℃, and bake until the big veins of the lower tobacco leaves are half white and the small veins are half dry.

[0061] Step 7: In the early stage of color fixation, continue to ventilate vigorously until the big veins are slightly green and the small veins are completely dry. When the big veins of the lower tobacco leaves are half white and the small veins are half dry, keep the cold air inlet door open at the maximum, continue to ventilate and dehumidify, raise the dry bulb to 48℃ for 8 hours, bake at a constant temperature for 16 hours, wet bulb at 32℃, and the circulating fan runs at high speed; bake until the big veins of the lower tobacco leaves are slightly green and the small veins are completely dry.

[0062] Step 8: After the color fixation, continue to ventilate vigorously until the big veins begin to shrink. After the small veins of the lower tobacco leaves are completely dry, keep the cold air inlet door open at the maximum, continue to ventilate and dehumidify, raise the dry bulb to 54℃ for 6 hours, bake at a constant temperature for 12 hours, wet bulb at 32℃, and run the circulating fan at high speed until the big veins of the lower tobacco leaves shrink.

[0063] Step 9: In the early stage of drying, keep ventilation high until the tobacco leaves shrink and turn half purple. After the tobacco leaves begin to shrink, keep the cold air inlet door open at the maximum, keep ventilation high to remove moisture, raise the dry bulb to 60℃ for 6 hours and keep the temperature stable for 8 hours, wet bulb at 34℃, and run the circulating fan at high speed until the tobacco leaves shrink and turn half purple.

[0064] Step 10: In the late stage of drying, continue to ventilate the leaves until the leaves shrink and turn purple. When the leaves shrink and turn purple by half, keep the cold air inlet door open at the maximum, continue to ventilate the leaves to remove moisture, raise the dry bulb to 68℃ for 8h, bake at a constant temperature for 20h, wet bulb at 34℃, and run the circulating fan at high speed until the leaves shrink and turn purple.

[0065] Baking process of the present invention:

[0066] The first step is to fill the tobacco leaves densely on the top and thinly on the bottom to prevent stiffness. According to the maturity, high, medium and low, they are placed in the upper, middle and lower layers of the curing room, densely on the top and thinly on the bottom. From top to bottom, 112 clips, 104 clips, 96 clips and 88 clips are placed respectively to prevent the tobacco leaves from being too wet in the middle and lower layers, which will not soften sufficiently and become stiff after curing. Each layer should be filled and evenly filled. There are 4 layers, a total of 400 clips. Set the curing scheme parameters as shown in Table 3. After the parameters are set, adjust the status indicator box to the initial position, turn on the low speed gear of the circulating fan, and ignite the curing.

[0067] Table 3 Baking scheme parameters

[0068]

[0069] The second step is to reduce humidity slightly in the early stage of yellowing, and the tip turns yellow. Keep the starting target dry-bulb and wet-bulb temperature at 32℃ for 12 hours after the tobacco leaves are preheated, and then increase the dry-bulb temperature to 36℃ and the wet-bulb temperature to 35℃ for 4 hours and bake for 20 hours. Reduce humidity appropriately to prevent the tobacco leaves from getting moldy. The program automatically controls the opening of the cold air inlet door, and the circulating fan is kept at a low speed. Bake until the tip of the upper tobacco leaves turns yellow. Observe the water mist on the inner wall of the window glass and the tobacco leaves sweat.

[0070] The third step is to reduce humidity in the middle of yellowing, and observe the tobacco to reduce humidity, and make it completely yellow and soft. After the tip of the upper tobacco leaves turns yellow, raise the dry bulb to 38℃ and the wet bulb to 36℃ for 4 hours, bake for 6 hours, bake until the upper tobacco leaves turn 80% yellow and the leaves are soft, adjust the wet bulb to 35℃, bake for 6 hours, bake until the middle tobacco leaves turn 80% yellow and the leaves are soft, adjust the wet bulb to 34℃, bake for 6 hours, bake until the lower tobacco leaves turn 80% yellow and the leaves are soft, keep the wet bulb to 34℃, bake for 14 hours, bake until the lower tobacco leaves turn completely yellow and soft, and collect the strips to avoid excessive yellowing of tobacco leaves, insufficient water loss, and stiff and non-soft tobacco leaves after baking. After the tip of the upper tobacco leaves turns yellow, observe the water mist on the inner wall of the window glass, hang two leaves of the left and right dehumidification windows, program the opening of the cold air inlet door, and adjust the circulating fan to high gear to prevent tobacco leaves from mildewing.

[0071] Step 4: In the late stage of yellowing, observe the window to reduce humidity, small tendons are half white, and large tendons are completely soft. After the lower layer of tobacco leaves are completely yellow, observe the fog on the inner wall of the window glass, hang up all the leaves of the left and right dehumidification windows, keep the circulating fan running at high speed, program the opening of the cold air inlet door, place a small wooden block at the lower end of the cold air inlet door frame, do not close the damper, keep the ventilation smooth, and avoid the tobacco leaves from being baked black. Raise the dry bulb to 40℃ for 8h and the wet bulb to 34℃ for 6h. Observe that there is still fog on the inner wall of the window glass. Adjust the wet bulb temperature to 33℃ and bake for 6h. The inner wall of the lower observation window glass is still foggy. Adjust the wet bulb temperature to 32℃ and bake for 4h. The inner wall of the lower observation window glass is clean and fog-free. The small tendons of the lower tobacco leaves are half white, and the large tendons are completely soft. Avoid the humidity in the baking room, which makes the large tendons not soft enough and bake black and stiff.

[0072] Step 5. In the late stage of yellowing, observe the dehumidification window, the small tendons are completely white, and the hook tip curls. After the small tendons of the lower tobacco leaves are half white and the large tendons are completely soft, keep all the leaves of the left and right dehumidification windows hung up, keep the circulating fan running at high speed, program the opening of the cold air inlet door, and place a small wooden block at the bottom of the cold air inlet door frame to keep ventilation smooth and prevent the tobacco leaves from turning black. Raise the dry bulb to 42℃ and the wet bulb to 32℃ for 8 hours and bake for 6 hours. There is no fog on the inner wall of the lower observation window glass. Maintain the dry bulb at 42℃ and the wet bulb at 32℃ for 10 hours, bake until the small tendons of the lower tobacco leaves are completely white and the hook tip curls, to avoid insufficient whitening of the small tendons and blue tendons after baking.

[0073] Step 6. In the early stage of color fixing, check the window for moisture removal, and the big tendons are completely white and the small tendons are half dry. The small tendons of the lower tobacco leaves are completely white, and after the hook tip is curled, keep all the leaves of the left and right moisture removal windows hung up, keep the circulating fan running at high speed, program the opening of the cold air inlet door, and place a small wooden block at the lower end of the cold air inlet door frame to keep ventilation unobstructed and prevent the tobacco leaves from turning black. Raise the dry bulb to 44℃ for 8h, keep the wet bulb at 32℃ and bake for 6h, observe that there is no fog on the inner wall of the window glass, maintain the dry bulb at 44℃ and the wet bulb at 32℃ and bake for 6h, bake until the big tendons of the lower tobacco leaves are completely white and the small tendons are half dry, and avoid baking black due to excessive humidity, and baking green and stiff due to excessive humidity.

[0074] Step 7: In the early stage of color fixation, check the window for moisture removal, the big tendons are all yellow, and the base of the small tendons is not dry. When the big tendons of the lower tobacco leaves are all white and the small tendons are half dry, keep all the leaves of the left and right moisture removal windows hung up, keep the circulating fan running at high speed, program the opening of the cold air inlet door, and place a small wooden block at the bottom of the cold air inlet door frame to keep ventilation smooth and prevent the tobacco leaves from turning black. Raise the dry bulb to 48℃ and the wet bulb to 34℃ for 8 hours, bake at a constant temperature for 6 hours, observe that there is no fog on the inner wall of the window glass, maintain the dry bulb at 48℃ and the wet bulb at 34℃ for 6 hours, bake until the big tendons of the lower tobacco leaves are all yellow and the base of the small tendons is not dry, avoid excessive humidity and variegated tobacco leaves, and avoid too low humidity and baking green and stiffness.

[0075] Step 8. In the later stage of color fixation, the humidity is increased appropriately, the small tendons are completely dry, and the color difference becomes smaller. After the large tendons of the lower tobacco leaves are completely yellow, keep all the leaves of the left and right dehumidification windows hung up, keep the circulating fan running at high speed, program the opening of the cold air inlet door, keep a small wooden block at the bottom of the cold air inlet door frame, keep ventilation smooth, and prevent the tobacco leaves from turning darker. Raise the dry bulb to 54℃ and the wet bulb to 36℃ for 9 hours, bake at a constant temperature for 6 hours, observe that there is no fog on the inner wall of the window glass, keep the dry bulb at 54℃ and the wet bulb at 36℃ for 10 hours, bake until the small tendons of the lower layer are completely dry, and the color difference between the front and back of the tobacco leaves becomes smaller, avoid excessive humidity, and the inner leaves are not dry and baked with mixed colors.

[0076] The ninth step is to increase humidity and stabilize humidity in the early stage of drying the tobacco leaves. The large tobacco leaves shrink and turn half purple. After the small tobacco leaves in the lower layer are completely dry, close all the leaves of the dehumidification window, adjust the circulating fan to run at a low speed, program the opening of the cold air inlet door, and remove the small wooden block at the bottom of the cold air inlet door frame. Raise the dry bulb to 60℃ and the wet bulb to 38℃ for 6 hours, and bake at a stable temperature for 8 hours until the large tobacco leaves in the lower layer shrink and turn half purple. Avoid baking with too high humidity and redness, and poor oil content due to too low humidity.

[0077] Step 10: In the late stage of drying, stabilize the temperature and humidity, and all the big tendons will shrink and turn purple. After the big tendons of the lower tobacco leaves shrink and turn purple by half, the program controls the opening of the cold air inlet door and the dehumidification port, and keeps the circulating fan running at a low speed. Raise the dry bulb to 68℃ and the wet bulb to 39℃ for 8 hours, and bake at a stable temperature for 20 hours until the big tendons of the lower tobacco leaves shrink, turn purple and harden. Avoid excessive temperature and humidity to bake the tobacco leaves red, drastically reduce the temperature to soak the tendons and leaves, and too low humidity to cause poor oil content in the tobacco leaves.

[0078] The tobacco leaves cured by the present invention and the traditional curing process are evaluated and analyzed from the aspects of tobacco leaf output value, appearance quality, chemical composition, etc.

[0079] Test results:

[0080] 1. Impact on tobacco leaf output value

[0081] As shown in Table 4, compared with the traditional baking technology, the proportion of high-quality tobacco in the present invention is increased by 5.15 percentage points, the proportion of medium-quality tobacco is reduced by 3.15 percentage points, the average price is increased by 1.5 yuan / kg, and the output value is increased by 3375 yuan / hm2. 2 .

[0082] Table 4 Comparison of tobacco leaf output value

[0083] project Ratio of high-quality smoke (%) Medium smoke ratio (%) Average price (yuan / kg) <![CDATA[Output value (yuan / hm 2 )]]> invention 56.78 36.22 26.04 58590.00 Tradition 51.63 39.37 24.54 55215.00

[0084] 2. Impact on the appearance quality of tobacco leaves

[0085] As shown in Table 5, the appearance of the tobacco leaves after flue-curing of the present invention is superior to that of the traditional flue-curing technology in terms of leaf structure, maturity, identity, oil content and chroma, the yellow tobacco rate is increased by 2.0 percentage points, the mixed color tobacco rate is reduced by 0.9 percentage points, and the green tobacco rate is reduced by 1.1 percentage points.

[0086] Table 5 Comparison of tobacco leaf appearance quality

[0087]

[0088] 3. Impact on the chemical composition of tobacco leaves

[0089] As shown in Table 6, the total sugar and reducing sugar of the flue-cured tobacco leaves of the present invention are higher, and the nicotine is lower. The total sugar is 29.4%, and the reducing sugar is 24.95%, which are 4.19% and 0.89% higher than the traditional ones respectively. The nicotine is 3.92%, which is 0.41% lower than the traditional ones.

[0090] Table 6 Comparison of chemical components of tobacco leaves

[0091] project Total sugar (%) Reducing sugar (%) Nicotine(%) invention 29.40 24.95 3.92 Tradition 25.21 24.06 4.33

[0092] 4. Evaluation of tobacco leaf baking effect

[0093] In summary, the present invention can effectively improve the proportion of high-quality tobacco and the appearance quality of flue-cured tobacco leaves, coordinate the chemical components of tobacco leaves, and improve the industrial availability of tobacco leaves.

[0094] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. The process of softening tobacco leaves in the upper part of the descending intensive curing barn is characterized by: The following steps are involved: The first step is to load the smoke with dense smoke at the top and thin smoke at the bottom, close the doors and windows, set the baking process parameters, adjust the baking curve status indicator box to the initial position, start the circulating fan at low speed, and ignite the baking; The second step is to maintain the starting target dry-bulb and wet-bulb temperature at 32℃ for 12-18h. After the tobacco leaves are preheated, the dry-bulb temperature is raised to 36℃ for 4h and the wet-bulb temperature is raised to 35-34℃ for 18-24h. The program automatically controls the opening of the cold air inlet door, and the circulating fan is kept at a low speed. The tobacco leaves on the upper layer are baked until the tip turns yellow. It is observed that there is water mist on the inner wall of the window glass and the tobacco leaves are sweating. Step 3: Raise the dry bulb to 38℃ and the wet bulb to 36℃ for 4 hours, bake until the upper tobacco leaves turn 80% yellow and become soft, adjust the wet bulb to 35℃, bake until the middle tobacco leaves turn 80% yellow and become soft, adjust the wet bulb to 34℃, bake until the lower tobacco leaves turn 80% yellow and become soft, keep the wet bulb at 34℃, bake until the lower tobacco leaves turn completely yellow and become soft, and keep the wet bulb temperature at more than 6 hours when the wet bulb temperature is lowered by 1℃; bake at a steady temperature of 38℃ for 24-36 hours. After the tip of the upper tobacco leaves turns yellow, observe the water mist on the inner wall of the window glass, hang two leaves of the left and right dehumidification windows, control the opening of the cold air inlet door with a program, and adjust the circulating fan to high gear; Step 4: If the inner wall of the window glass is still foggy, hang up all the blades of the left and right dehumidification windows, keep the circulating fan running at high speed, program the opening of the cold air inlet door, place a small wooden block at the lower end of the cold air inlet door frame, do not close the door tightly, and keep the ventilation smooth; raise the dry bulb temperature to 40℃ and the wet bulb temperature to 34℃ for 8 hours and bake for about 6 hours. If the inner wall of the window glass is still foggy, reduce the wet bulb temperature by 1℃ every 6 hours, and the wet bulb temperature can be below 31℃ until the fog disappears and no longer be reduced. Bake at a steady temperature of 40℃ for 12-18 hours until the small tendons of the lower tobacco leaves are half white and the large tendons are completely soft; Step 5: Keep all blades of the left and right dehumidification windows up, keep the circulating fan running at high speed, program-control the opening of the cold air inlet door, keep a small wooden block at the bottom of the cold air inlet door frame to keep ventilation smooth; raise the dry bulb to 42℃ for 8 hours and the wet bulb to 32℃ for about 6 hours. If fog is observed on the inner wall of the window glass, reduce the wet bulb temperature by 1℃ every 6 hours. The wet bulb temperature can be below 30℃ until the fog disappears and no longer be reduced. Bake at a steady temperature of 42℃ for 12-18 hours until the small tendons of the lower tobacco leaves are completely white and the hook tips are curled; Step 6: Keep all blades of the left and right dehumidification windows up, keep the circulating fan running at high speed, program-control the opening of the cold air inlet door, keep a small wooden block at the bottom of the cold air inlet door frame to keep ventilation unobstructed; raise the dry bulb to 44℃ and the wet bulb to 32℃ for 8 hours and bake for about 6 hours. If fog is observed on the inner wall of the window glass, reduce the wet bulb temperature by 1℃ every 6 hours or so, and the wet bulb temperature can be below 30℃ until the fog disappears and no longer be reduced. Bake at a steady temperature of 44℃ for 12-18 hours until the large tendons of the lower tobacco leaves are completely white and the small tendons are half dry; Step 7: Keep all blades of the left and right dehumidification windows up, keep the circulating fan running at high speed, program-control the opening of the cold air inlet door, keep a small wooden block at the bottom of the cold air inlet door frame to keep ventilation smooth; raise the dry bulb to 48℃ and the wet bulb to 34℃ for 8 hours and bake for about 6 hours. If the inner wall of the window glass is foggy, lower the wet bulb temperature by 1℃. Every 6 hours of baking, lower the wet bulb temperature by 1℃. The wet bulb temperature can be below 32℃ until the fog disappears and no longer be lowered. Bake at a steady temperature of 48℃ for 10-16 hours until the large tendons of the lower tobacco leaves are completely yellow and the base of the small tendons is not dry; Step 8: Keep all blades of the left and right dehumidification windows hung up, keep the circulating fan running at high speed, program-control the opening of the cold air inlet door, keep a small wooden block at the bottom of the cold air inlet door frame to keep ventilation smooth; raise the dry bulb to 54℃ and the wet bulb to 36℃ for 9 hours and bake for about 6 hours. If the inner wall of the window glass is foggy, lower the wet bulb temperature by 1℃. Every 6 hours of baking, lower the wet bulb temperature by 1℃. The wet bulb temperature can be below 34℃ until the fog disappears and no longer lowered. Bake at a steady temperature of 54℃ for 12-18 hours until the small tendons in the lower layer are completely dry and the color difference between the front and back of the tobacco leaves becomes smaller; The ninth step is to close all the blades of the dehumidification window, adjust the circulating fan to run at a low speed, program the opening of the cold air inlet door, and remove the small wooden block at the bottom of the cold air inlet door frame; raise the dry bulb to 60℃ and the wet bulb to 38℃ for 6 hours, and bake at a steady temperature for 8-12 hours until the tobacco leaves on the lower layer shrink and turn half purple; The tenth step is to control the opening of the cold air inlet door and the moisture exhaust port through the program to keep the circulating fan running at a low speed; raise the dry bulb to 68°C and the wet bulb to 39°C in 8 hours, and bake at a steady temperature for 16-24 hours until the large veins of the lower layer of tobacco leaves have all shrunk, turned purple and hardened.

2. The process for softening tobacco leaves in the upper part of the descending intensive curing barn according to claim 1 is characterized in that: In the first step, the tobacco leaves on the same kang are of the same variety and have the same maturity level. They are loaded into the upper, middle and lower layers according to their high, medium and low maturity levels, with the upper layer being dense and the lower layer being sparse, so that the tobacco is filled and evenly loaded.

3. The process for softening tobacco leaves in the upper part of the descending type intensive curing barn according to claim 1 is characterized in that: In the first step, the baking process parameters are ten target dry-bulb stable temperature points, the first stable temperature point dry-bulb temperature is 32°C, the wet-bulb temperature is 32°C, the stable temperature is 12-18h, the second stable temperature point dry-bulb temperature is 36°C, the wet-bulb temperature is 35-34°C, the stable temperature is 18-24h, and the heating time is 4h, the third stable temperature point dry-bulb temperature is 38°C, the wet-bulb temperature is 36-34°C, the stable temperature is 24-36h, and the heating time is 4h, the fourth stable temperature point dry-bulb temperature is 40°C, the wet-bulb temperature is 34-31°C, the stable temperature is 12-18h, and the heating time is 8h, the fifth stable temperature point dry-bulb temperature is 42°C, the wet-bulb temperature is 32-30°C, the stable temperature is 12- 18h, heating time 8h, the sixth stable temperature point dry bulb temperature 44℃, wet bulb temperature 32-30℃, temperature stabilization 12-18h, heating time 8h, the seventh stable temperature point dry bulb temperature 48℃, wet bulb temperature 34-32℃, temperature stabilization 10-16h, heating time 8h, the eighth stable temperature point dry bulb temperature 54℃, wet bulb temperature 36-34℃, temperature stabilization 12-18h, heating time 9h, the ninth stable temperature point dry bulb temperature 60℃, wet bulb temperature 38℃, temperature stabilization 8-12h, heating time 6h, the tenth stable temperature point dry bulb temperature 68℃, wet bulb temperature 39℃, temperature stabilization 16-24h, heating time 8h.

4. The process for softening tobacco leaves in the upper part of a descending intensive curing barn according to claim 1, characterized in that: The speed of the circulating fan corresponding to the low speed gear is 720r / min, and the speed corresponding to the high speed gear is 1440r / min.

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