Baking method for coping with flue-cured tobacco leaf picking in rainy days

Abstract

According to the curing method, a pole-changing speed-regulating motor, an air return baffle, a motor reversing switch and other devices are installed in an airflow descending type bulk curing barn and used in cooperation with the airflow descending type bulk curing barn, on the basis that the tobacco weaving and packaging amount of the flue-cured tobacco leaves picked on the rainy days is reduced by 10%-20% under the normal weather condition, the flue-cured tobacco leaves are cured at the curing dry-bulb temperature of 30 DEG C-40 DEG C, and then the flue-cured tobacco leaves are cured on the basis of the baking dry-bulb temperature of 30 DEG C-40 DEG C; the axial flow fan is subjected to sine type forward rotation and reverse rotation treatment through a reversing switch until the dry-bulb temperature is 40 DEG C, and airflow descending operation and airflow ascending operation are repeatedly achieved before the dry-bulb temperature of airflow in the tobacco loading chamber is 40 DEG C; the tobacco leaves in the tobacco loading chamber are uniformly heated in a yellowing period; the temperature is uniformly and sectionally increased and stabilized in a color fixing period; the coordination of yellowing and water loss of the flue-cured tobacco leaves in rainy days is promoted; the tobacco leaves shrink a reel; the invention relates to a baking method suitable for improving the overall baking quality of flue-cured tobacco leaves picked in rainy days.

Description

Technical Field

[0001] The invention relates to the field of tobacco leaf baking and curing, and in particular to a baking method for tobacco leaves picked and cured on rainy days under rainy weather conditions. Background Art

[0002] Flue-curing is an important link in determining the quality of flue-cured tobacco production. The core technology of tobacco leaf flue-curing is the coordination of yellowing and water loss. There is a lot of rainfall during the harvesting and curing of lower tobacco leaves and middle and lower tobacco leaves in the southeast tobacco area. When tobacco leaves are harvested and cured in rainy weather, the ambient air humidity is high and the water content of tobacco leaves is high. It is easier for tobacco leaves to turn yellow, but it is more difficult to lose water. If the operation is improper, the tobacco leaves will be thin, light in color, smooth and stiff after baking at the least; in severe cases, the tobacco leaves in the high-temperature layer will be baked green and the tobacco leaves in the low-temperature layer will be baked to stale. The reason is that tobacco leaves are harvested and baked on rainy days, the tobacco leaves have a high water content and there is even visible water on the surface of the tobacco leaves. During the baking process, the air humidity is high and the intensive baking room has forced ventilation. Especially during the yellowing period of tobacco leaves, the tobacco leaves in the high-temperature layer are in a high-temperature and low-humidity environment for a long time, and the tobacco leaves lose water too early and too much and contain green, while the tobacco leaves in the low-temperature layer are in a low-temperature and high-humidity environment for a long time, and the tobacco leaves are easy to stick together and consume too much respiration, becoming thin and baked to stale. Therefore, it is necessary to create a temperature and humidity environment that is conducive to the yellowing and water loss of tobacco leaves during the intensive baking and yellowing period, promote the reasonable heating and timely water loss of tobacco leaves in different layers in the tobacco loading room, and reduce the adverse effects of tobacco leaves harvested and baked on rainy days on the quality of tobacco leaves.

[0003] "A method for harvesting and baking in dense curing houses in rainy tobacco areas (ZL201410082301.3)" discloses a method for harvesting and baking in dense curing houses in rainy tobacco areas, which plays a significant role in improving the baking quality of tobacco leaves under rainy conditions in the southeastern tobacco areas. However, during the process of picking tobacco leaves and baking tobacco leaves on rainy days, there is obvious moisture on the surface of the tobacco leaves, and the low-temperature layer of tobacco leaves will stick together, resulting in uneven heating, so that the low-temperature layer of tobacco leaves cannot turn yellow and lose water in time, and shrink the rolls, resulting in thin baking residue, which affects the baking quality of tobacco leaves. Summary of the invention

[0004] The present invention aims to provide a baking method for tobacco leaves harvested and cured on rainy days. The baking method can shake off the surface water of tobacco leaves in a tobacco loading room when tobacco leaves are harvested and cured on rainy days, especially the lower leaves and the middle and lower leaves, thereby reducing the adhesion of tobacco leaves, promoting uniform heating of tobacco leaves in the tobacco loading room of a dense airflow-down curing room during the yellowing period, uniform and segmented temperature rise and temperature stabilization during the color fixing period, promoting the coordination of yellowing and water loss of tobacco leaves harvested and cured on rainy days, shrinking and rolling of tobacco leaves, reducing the baking of green leaves in the high-temperature layer, baking thin dregs in the low-temperature layer, and making the base smooth, thereby improving the overall baking quality of tobacco leaves harvested and cured on rainy days. The method has the characteristics of simple operation, scientific and practical, and obvious effect.

[0005] The object of the present invention is achieved in that: A method for curing tobacco leaves picked and cured on rainy days, characterized by the following specific steps: Ⅰ. Installation of curing room equipment: In the smoke loading room of the airflow descending intensive curing room, the tobacco is hung in a three-layer two-way manner, and the automatic control instrument is used to control the tobacco leaf curing. The upper and lower layers of the smoke loading room are respectively installed with temperature and humidity sensors; a pole-changing speed regulating motor and an axial flow fan are installed above the heating room of the airflow descending intensive curing room; a return air baffle is installed in the return air outlet at the bottom of the partition wall of the heating room, an air outlet is opened at the upper end of the partition wall of the heating room, and a cold air inlet door is installed at the lower part of the front wall of the heating room; a forward and reverse switch is installed between the pole-changing speed regulating motor and the automatic control instrument to control the forward and reverse rotation of the pole-changing speed regulating motor; Ⅱ. Airflow direction of the airflow-down type intensive baking room: turn on the forward and reverse switch to rotate forward, the axial flow fan runs forward, and the airflow direction in the smoke-loading chamber of the airflow-down type intensive baking room is downward; turn on the reverse switch to rotate backward, the axial flow fan runs reversely, and the airflow direction in the smoke-loading chamber of the airflow-down type intensive baking room is upward; Ⅲ. Air circulation in airflow-down intensive baking room: Turn on the forward and reverse switch, and when the axial flow fan is running in the forward direction, adjust the opening and closing degree of the return air damper and the cold air inlet door to achieve different circulation exchanges between the smoke chamber, heating chamber and external environment of the airflow-down intensive baking room. There are mainly three circulation modes: A. Internal circulation: When the axial flow fan is running in the forward direction, the return air damper is fully or partially opened, the cold air inlet door is closed, and the air flow circulates between the heating chamber and the smoke loading chamber of the air flow down-type intensive baking room. No external air flow enters the air flow down-type intensive baking room, and there is no air discharge outside the air flow down-type intensive baking room; B. External circulation: When the axial flow fan is running in the forward direction, close the return air damper, open the cold air inlet door, and the outside air flows into the heating chamber through the cold air inlet door, then enters the smoke loading chamber from the air outlet at the upper end of the partition wall, and is discharged from the dense baking room through the dehumidification window; C. Internal and external circulation: When the axial flow fan is running in the forward direction, the return air damper is partially opened and the cold air inlet door is partially opened. The outside air flows into the heating chamber through the cold air inlet door, and enters the smoke loading chamber through the air outlet after being heated. Part of the air flows out of the air flow descending intensive baking room through the dehumidification window, and the other part of the air flows back to the heating chamber from the return air outlet to be heated again.

[0006] IV. Loading cigarettes: When picking tobacco leaves on rainy days, the amount of tobacco braided on a single tobacco rod should be reduced by 10% to 20% under normal weather conditions, with 130 to 140 pieces / rod; the amount of tobacco loaded in a single airflow-down intensive curing room should be reduced by 10% to 20%, with 320 to 340 rods / curing; after braiding, the tobacco rods should be hung on the hanging rack outside the airflow-down intensive curing room for 2h to 4h and drained appropriately; Ⅴ. Baking: Step 1: When picking and curing tobacco leaves on rainy days, the method of loading and igniting tobacco leaves is adopted to promote the temperature of the airflow descending intensive curing room to quickly increase to about 30℃; before ignition, set the temperature control point on the automatic controller; after ignition, the dry bulb temperature and wet bulb temperature are synchronously raised to 36℃ / 36℃ at a rate of 1℃ / h, and the temperature is stabilized for 3h~4h until the whole flue-cured tobacco leaves expand and sweat, and then the temperature begins to rise; before the dry bulb temperature is 30℃, turn on the reverse forward and reverse switch, the axial flow fan reverses at high speed, and the airflow circulates inside and outside; in the temperature range of 30℃~36℃, turn on the reverse forward and reverse switch, the axial flow fan reverses at low speed, and the airflow circulates inside; Step 2: After the 36℃ temperature stabilization is completed, the dry-bulb temperature and wet-bulb temperature are raised to 38℃ / 38℃ at a rate of 1℃ / h for 2h. During this period, the reverse and forward switches are turned on, the axial flow fan is reversed at a low speed, and the airflow circulates internally; then the forward and reverse switches are turned on, the axial flow fan is forward at a low speed, and low-speed forward rotation for 4h to dehumidify, the airflow circulates inside and outside, and then switched to low-speed reverse rotation, the dry and wet bulbs are kept at 38℃ / 36℃ for 4h, the airflow circulates inside and outside, and then switched to reverse rotation of the forward and reverse switches, the fan is reversed at a low speed, the dry and wet bulbs are kept at 38℃ / 36℃ for 4h, the airflow circulates inside and outside, and then switched to reverse rotation of the forward and reverse switches, the fan is reversed at a low speed, the dry and wet bulbs are kept at 38℃ / 36℃ for 4h, the airflow circulates inside and outside, and this is repeated until the middle tobacco leaves turn 70% to 80% yellow and the leaves become soft, and then the next step of baking is entered; Step 3: Raise the dry-bulb and wet-bulb temperatures to a steady 40°C / 37°C at a rate of 0.5°C / h until the middle tobacco leaves turn 80% to 90% yellow and most of the leaves wither and collapse, and then proceed to the next baking step; during this period, the axial flow fan performs sinusoidal forward and reverse rotation according to the cycle; When the dry-bulb temperature is between 30℃ and 40℃, the axial flow fan is subjected to sinusoidal forward and reverse rotation. From the time of ignition to the time of 30℃ dry-bulb temperature, the axial flow fan is reversed at high speed, and the airflow circulates inside and outside. From 30℃ to 36℃, the axial flow fan is reversed at low speed, and the airflow circulates inside. From 36℃ to 40℃ dry-bulb temperature, the axial flow fan is reversed at low speed, and the forward and reverse conversion frequency of the axial flow fan is 4h. A forward-reverse switch is used. After ignition, the forward-reverse switch is turned on to start the axial flow fan. The high speed gear of the axial flow fan is switched to high speed until the dry-bulb temperature rises to 30℃ / 30℃. After that, the axial flow fan is switched to low speed and runs for 4 hours. Then, the forward and reverse switch is turned on. The axial flow fan rotates forward at low speed. After running for another 4 hours, the reverse switch is turned on. The axial flow fan is switched to low speed and reverses. One forward and reverse sinusoidal cycle is completed. Then, the same sinusoidal cycle is switched until the dry-bulb temperature reaches 40℃ and the forward and reverse switching operation of the axial flow fan is terminated. The conversion process is carried out for a total of 24h to 38h. Step 4: Raise the dry-bulb and wet-bulb temperatures to a steady 42℃ / 36℃ at a rate of 0.5℃ / h until 30%-50% of the tobacco leaves in the middle layer have slightly hooked tips, and the tobacco leaves in the low-temperature layer turn 90% yellow and the main veins become soft and completely wither and collapse before entering the next step of baking; during this period, the axial flow fan runs in the forward direction, and the high and low speed gears are flexibly switched according to the wet-bulb temperature in the airflow descending intensive baking room, with the high speed gear as the main gear, the airflow circulates inside and outside, and the return air damper is closed by 1 / 2 to 2 / 3; Step 5: Raise the dry-bulb temperature to 45℃ / 37℃ at a rate of 0.3℃~0.4℃ / h, keep the temperature steady for 4h~6h, then raise the dry-bulb temperature to 48℃ / 37℃~38℃ at a rate of 0.3℃~0.4℃ / h, keep the temperature steady until the middle layer of tobacco leaves have yellow flakes and yellow tendons, and most of the tobacco leaves are small rolls, then raise the dry-bulb temperature to 51℃ / 39℃ at a rate of 0.5℃ / h, keep the temperature steady for 4h~6h, then raise the dry-bulb temperature to 54℃ / 40℃ at a rate of 0.5℃~0.67℃ / h, keep the temperature steady until the low temperature layer of tobacco leaves are large rolls; Step 6: Raise the dry-bulb and wet-bulb temperatures to a steady state of 60°C / 41°C at a rate of 1°C / h. When 2 / 3 of the main veins of the whole-cured tobacco leaves are dry, raise the dry-bulb and wet-bulb temperatures to a steady state of 65°C-67°C / 41°C-42°C at a rate of 0.5°C / h. Stop heating when the main veins of the whole-cured tobacco leaves are completely dry, and the curing is completed.

[0007] Furthermore, in step V. the first step of baking, in order to prevent the tobacco leaves in the low-temperature layer from sticking, before the dry-bulb temperature reaches 30°C after ignition, an axial flow fan is used to reverse at high speed and circulate the air inside and outside, so that the tobacco leaves in the low-temperature layer are swung by high-speed wind, and part of the visible water on the surface of the tobacco leaves is shaken while shaking the tobacco leaves.

[0008] Furthermore, in step V. the first step of baking, in the temperature range of 30°C to 36°C, the axial flow fan is reversed at a low speed, and the air flow circulates internally, which can promote the increase of the temperature of the tobacco leaves in the low-temperature layer. At the same time, the internal circulation of the air flow can reduce the temperature difference between the upper and lower layers in the tobacco loading chamber. Moreover, since the tips of the tobacco leaves are slowly heated by the wind first, the greening caused by the long-term heating of the base of the tobacco leaves by the wind can be avoided.

[0009] Furthermore, in step V. the second and third steps of baking, when the dry-bulb temperature is in the heating and stabilization stages between 36°C and 40°C, a sinusoidal switching method of switching the axial flow fan between forward and reverse rotation every 4 hours is adopted, which can take into account the heating and wind conditions of the upper and lower tobacco leaves in the loading chamber of the airflow descending intensive curing room. At the same time, due to the continuous switching of the airflow direction in the loading chamber, the water on the surface of the tobacco leaves can be gradually shaken off, and the temperatures of the upper and lower layers in the loading chamber tend to be uniform, thereby solving the problem of high temperature and low humidity in the loading chamber of the airflow descending intensive curing room during rainy weather, and the upper tobacco leaves in the loading chamber of the loading chamber are in a state of high temperature and low humidity for a long time, while the lower tobacco leaves in the loading chamber are in a state of low temperature and high humidity for a long time, thereby promoting the coordination of yellowing and water loss of the upper and lower tobacco leaves in the loading chamber, reducing the appearance of green roasted leaves on the upper layer and thin roasted dregs on the lower layer, improving the baking quality and uniformity of tobacco leaves, and coping with the heating and dehumidification pressure and baking risks faced by tobacco leaves harvested and cured on rainy days.

[0010] Furthermore, in step V. the second step of baking, regarding air flow circulation: ignite while loading tobacco, and after loading and baking, the axial flow fan first runs forward at high speed for 30 minutes, and the airflow circulates outside, and then switches to reverse high-speed operation for 30 minutes, and the airflow circulates inside and outside until the dry-bulb temperature reaches 30°C. At a relatively low temperature, the clear water on the surface of the tobacco leaves can be gradually shaken off to reduce tobacco leaf adhesion.

[0011] Furthermore, in step V. of the fifth step of baking, regarding the dry-bulb temperature point: the dry-bulb temperature is staged at 45°C, 48°C, 51°C and 54°C for temperature increase and temperature stabilization, and the dry-bulb temperature points are evenly distributed. In the tobacco loading room of the airflow-down intensive baking room, the temperature of the lower layer of tobacco leaves in the tobacco loading room can be gradually increased, and the yellowing and water loss coordination of the lower layer of tobacco leaves can be promoted, and the shrinkage and rolling of tobacco leaves can be promoted, and the occurrence of smoothness on both sides and the base of the main veins of tobacco leaves can be reduced, thereby improving the baking quality of tobacco leaves.

[0012] The present invention is based on "A method for harvesting and baking tobacco leaves in intensive curing barns in rainy tobacco producing areas (ZL201410082301.3)", and combines the structural characteristics of intensive curing barns with downward airflow, especially the structure of intensive curing barns with downward airflow in tobacco producing areas in Jiangxi Province, return air baffles installed in the curing barns, external variable-pole speed regulating motors and axial flow fans, etc., to further optimize and improve the baking operation method of tobacco leaves harvested and baked on rainy days.

[0013] Therefore, the present invention can shake off the surface water of the tobacco leaves in the tobacco loading room when the tobacco leaves, especially the lower leaves and the middle and lower leaves, are harvested and cured on rainy days, thereby reducing the adhesion of the tobacco leaves, promoting uniform heating of the tobacco leaves in the tobacco loading room of the airflow-down intensive curing room during the yellowing period, uniform and segmented temperature rise and temperature stabilization during the color fixing period, promoting the coordination of yellowing and water loss of the tobacco leaves harvested and cured on rainy days, and the shrinkage of the tobacco leaves, reducing the baking of the high-temperature layer, baking the thin baking dregs of the low-temperature layer, and making the base smooth, thereby improving the overall baking quality of the tobacco leaves harvested and cured on rainy days, and having the characteristics of simple operation, scientific and practical, and obvious effect. DETAILED DESCRIPTION

[0014] The present invention will be further described below in conjunction with the embodiments.

[0015] The present invention is further described in detail below by taking the example of harvesting and baking the second shed tobacco leaves of Yunyan 87 under rainy weather conditions. The specific steps are as follows: Ⅰ. Tobacco braiding and curing: Harvest tobacco leaves on rainy days. Braid about 140 tobacco leaves per tobacco stem, 2 leaves in a bundle, back to back; After braiding, hang the tobacco stems on the hanging rack outside the airflow descending intensive curing room for 3 hours and drain them appropriately; When packing, make sure to pack them full, densely and evenly. A large airflow descending intensive curing room can pack about 320 tobacco stems; Ⅱ. Installation of curing room equipment: In the smoke loading room of the airflow descending intensive curing room, the tobacco is hung in a three-layer two-way manner, and the automatic control instrument is used to control the tobacco leaf curing. The upper and lower layers of the smoke loading room are respectively installed with temperature and humidity sensors; a pole-changing speed regulating motor and an axial flow fan are installed above the heating room of the airflow descending intensive curing room; a return air baffle is installed in the return air outlet at the bottom of the heating room partition wall, an air outlet is installed at the upper end of the heating room partition wall, and a cold air inlet door is installed at the lower part of the front wall of the heating room; a forward and reverse switch is installed between the pole-changing speed regulating motor and the automatic control instrument to control the forward and reverse rotation of the pole-changing speed regulating motor; Ⅲ. Baking operation: Step 1: After all tobacco leaves are braided, drain them for 3 hours, and load all tobacco leaves into the tobacco loading chamber by igniting them while loading; before ignition, set the temperature starting point at 30℃ / 30℃ on the automatic controller, and after ignition, raise the dry-bulb temperature and wet-bulb temperature to 36℃ / 36℃ at a rate of 1℃ / h, and keep the temperature steady for 4 hours until the whole flue-cured tobacco leaves expand and sweat, and then start to heat up after synchronous preheating; When the dry-bulb temperature is below 30℃, turn on the reverse switch, the axial flow fan reverses at high speed, and the air circulates inside and outside. When the temperature is between 30℃ and 36℃, turn on the reverse switch, the axial flow fan reverses at low speed, and the air circulates inside. Step 2: After the 36℃ temperature stabilization is completed, the dry-bulb temperature and wet-bulb temperature are raised to 38℃ / 38℃ at a rate of 1℃ / h for 2h. During this period, the reverse and forward switches are turned on, the axial flow fan is reversed at a low speed, and the airflow circulates internally; then the forward and reverse switches are turned on, the axial flow fan is forward at a low speed, and low-speed forward rotation for 4h to dehumidify, the airflow circulates inside and outside, and then switched to low-speed reverse rotation, the dry and wet bulbs are kept at 38℃ / 36℃ for 4h, the airflow circulates inside and outside, and then switched to reverse rotation of the forward and reverse switches, the fan is reversed at a low speed, the dry and wet bulbs are kept at 38℃ / 36℃ for 4h, the airflow circulates inside and outside, and then switched to reverse rotation of the forward and reverse switches, the fan is reversed at a low speed, the dry and wet bulbs are kept at 38℃ / 36℃ for 4h, the airflow circulates inside and outside, and this is repeated until the middle tobacco leaves turn 70% to 80% yellow and the leaves become soft, and then the next step of baking is entered; Step 3: Raise the dry-bulb and wet-bulb temperatures to a steady 40°C / 37°C at a rate of 0.5°C / h until the middle tobacco leaves turn 80% to 90% yellow and most of the leaves wither and collapse, and then proceed to the next baking step; during this period, the axial flow fan performs sinusoidal forward and reverse rotation according to the cycle; When the dry-bulb temperature is between 30℃ and 40℃, the axial flow fan performs sinusoidal forward and reverse rotation. After ignition, from the stage of dry-bulb temperature to 30℃, the axial flow fan uses high-speed reverse rotation, and the airflow circulates inside and outside. At 30℃ to 36℃, the axial flow fan uses low-speed reverse rotation, and the airflow circulates inside. At the stage of dry-bulb temperature between 36℃ and 40℃, the axial flow fan uses low-speed, and the forward and reverse conversion frequency of the axial flow fan is 4h. A forward-reverse switch is used. After ignition, turn on the reverse switch to start The axial flow fan is in high gear until the dry-bulb temperature rises to 30℃ / 30℃. The axial flow fan is switched to low gear and runs for 4 hours. Then the forward and reverse switch is turned on. The axial flow fan rotates forward at low speed. After running for another 4 hours, the forward and reverse switch is turned on. The axial flow fan is switched to low gear and reverses. One forward and reverse cycle is completed. Then the corresponding cycle is switched until the dry-bulb temperature reaches 40℃ and the forward and reverse switching operation of the axial flow fan is terminated. The conversion process is carried out for a total of 24 to 38 hours. Step 4: Raise the dry-bulb and wet-bulb temperatures to a steady 42℃ / 36℃ at a rate of 0.5℃ / h until 30%-50% of the tobacco leaves in the middle layer have slightly hooked tips, and the tobacco leaves in the low-temperature layer turn 90% yellow and the main veins become soft, and completely wither and collapse before entering the next step of baking; during this period, the axial flow fan runs in the forward direction, and the high-speed and low-speed gears are flexibly switched according to the wet-bulb temperature in the airflow descending intensive baking room, with the high-speed gear as the main gear, the airflow circulates inside and outside, and the return air damper is closed by 1 / 2-2 / 3; Step 5: Raise the dry-bulb temperature to 45℃ / 37℃ at a rate of 0.3℃~0.4℃ / h and keep it steady for 4h, then raise the dry-bulb temperature to 48℃ / 37℃ at a rate of 0.4℃ / h and keep it steady until the middle layer of tobacco leaves turn yellow and yellow, and most of the tobacco leaves are small rolls, then raise the dry-bulb temperature to 51℃ / 39℃ at a rate of 0.5℃ / h and keep it steady for 4h, then raise the dry-bulb temperature to 54℃ / 40℃ at a rate of 0.5℃ / h and keep it steady until the low temperature layer of tobacco leaves turn into large rolls; Step 6: Raise the dry-bulb and wet-bulb temperatures to a steady state of 60°C / 41°C at a rate of 1°C / h. When 2 / 3 of the main veins of the whole-cured tobacco leaves are dry, raise the dry-bulb and wet-bulb temperatures to a steady state of 65°C / 41°C at a rate of 0.5°C / h. Stop heating when the main veins of the whole-cured tobacco leaves are completely dry, and the curing is completed.

[0016] In the first step, in order to prevent the tobacco leaves in the low-temperature layer from sticking together, before the dry-bulb temperature reaches 30°C after ignition, the axial flow fan is used to reverse at high speed and circulate the air inside and outside to swing the tobacco leaves in the low-temperature layer through high-speed wind, shaking the leaves and shaking off some of the visible water on the surface of the leaves.

[0017] In the first step, in the temperature range of 30℃ ~ 36℃, the axial flow fan is reversed at low speed, and the air flow circulates internally, which can promote the temperature increase of the tobacco leaves in the low-temperature layer. At the same time, the internal circulation of the air flow can reduce the temperature difference between the upper and lower layers in the tobacco loading room. Since the tips of the tobacco leaves are heated slowly by the wind first, the base of the tobacco leaves can be avoided from being roasted due to long-term heating by the wind.

[0018] In the second and third steps, when the dry-bulb temperature is in the stage of heating and stabilizing at 36℃~40℃, the axial flow fan is switched between forward and reverse every 4 hours, which can take into account the heating and wind conditions of the upper and lower tobacco leaves in the loading chamber of the airflow descending intensive curing room. At the same time, due to the continuous switching of the airflow direction in the loading chamber, the water on the surface of the tobacco leaves can be gradually shaken off, and the temperatures of the upper and lower layers in the loading chamber tend to be uniform. This solves the problem of high temperature and low humidity in the upper layer of the loading chamber of the airflow descending intensive curing room during rainy weather, while the lower layer of the tobacco leaves in the loading chamber are in a state of low temperature and high humidity for a long time. This promotes the coordination of yellowing and water loss of the upper and lower layers of the tobacco leaves in the loading chamber, reduces the appearance of green roasted leaves on the upper layer and thin roasted dregs on the lower layer, improves the quality and uniformity of tobacco leaf baking, and copes with the heating and dehumidification pressure and baking risks faced by tobacco leaves harvested on rainy days.

[0019] In the second step, regarding air flow circulation: ignite while loading the tobacco leaves. After loading and baking, the axial flow fan will first run forward at high speed for 30 minutes, and the air flow will circulate outside. Then it will turn to reverse and run at high speed for 30 minutes. The air flow will circulate inside and outside until the dry bulb temperature reaches 30℃. At a relatively low temperature, the clear water on the surface of the tobacco leaves can be gradually shaken off to reduce the adhesion of the tobacco leaves.

[0020] In step 5, regarding the dry-bulb temperature points: the dry-bulb temperature is staged at 45°C, 48°C, 51°C and 54°C for temperature increase and stabilization. The dry-bulb temperature points are evenly distributed. In the tobacco loading room of the airflow-down intensive curing room, the temperature of the lower layer of tobacco leaves in the tobacco loading room can be gradually increased, which can promote the coordinated yellowing and water loss of the lower layer of tobacco leaves, promote the shrinkage and rolling of tobacco leaves, reduce the occurrence of smoothness on both sides and base of the main veins of tobacco leaves, and thus improve the baking quality of tobacco leaves.

[0021] In the baking example, the green tobacco ratio, smooth tobacco ratio, orange tobacco ratio, upper and middle tobacco ratio and average price of the process of the present invention are greatly improved compared with the control process, and the economic benefit and appearance quality test process of the tobacco leaves after baking are obviously better, as shown in Table 1 below.

[0022] Table 1 Effects of the process of the present invention and the control process on the quality of tobacco leaf baking

[0023] Finally, it should be emphasized that the above-mentioned implementation cases are only used to illustrate the technical solutions of the present invention, and do not constitute a limitation thereto. Although the present invention has been elaborated in detail through the above-mentioned implementation cases, professionals and technicians in this field should understand that they still have the right to make necessary adjustments to the technical solutions recorded in the above-mentioned implementation cases, or to make equivalent replacements for some of the technical features therein. Such adjustments or replacements will not cause the essence of the relevant technical solutions to deviate from the core spirit and scope of the technical solutions of the implementation cases of the present invention. Therefore, the scope of protection of the present invention should not be limited to the above-mentioned specific implementation cases, but should be based on the scope defined in the claims.

Claims

1. A method for curing tobacco leaves picked and cured on rainy days, characterized in that: Ⅰ. Installation of curing room equipment: In the smoke loading room of the airflow descending intensive curing room, the tobacco is hung in a three-layer two-way manner, and the automatic control instrument is used to control the tobacco leaf curing. The upper and lower layers of the smoke loading room are respectively installed with temperature and humidity sensors; a pole-changing speed regulating motor and an axial flow fan are installed above the heating room of the airflow descending intensive curing room; a return air baffle is installed in the return air outlet at the bottom of the partition wall of the heating room, an air outlet is opened at the upper end of the partition wall of the heating room, and a cold air inlet door is installed at the lower part of the front wall of the heating room; a forward and reverse switch is installed between the pole-changing speed regulating motor and the automatic control instrument to control the forward and reverse rotation of the pole-changing speed regulating motor; Ⅱ. Airflow direction of the airflow-down type intensive baking room: turn on the forward and reverse switch to rotate forward, the axial flow fan runs forward, and the airflow direction in the smoke-loading chamber of the airflow-down type intensive baking room is downward; turn on the reverse switch to rotate backward, the axial flow fan runs reversely, and the airflow direction in the smoke-loading chamber of the airflow-down type intensive baking room is upward; Ⅲ. Air circulation in airflow-down intensive baking room: Turn on the forward and reverse switch, and when the axial flow fan is running in the forward direction, adjust the opening and closing degree of the return air damper and the cold air inlet door to achieve different circulation exchanges between the smoke chamber, heating chamber and external environment of the airflow-down intensive baking room. There are mainly three circulation modes: A. Internal circulation: When the axial flow fan is running in the forward direction, the return air damper is fully or partially opened, the cold air inlet door is closed, and the air flow circulates between the heating chamber and the smoke loading chamber of the air flow down-type intensive baking room. No external air flow enters the air flow down-type intensive baking room, and there is no air discharge outside the air flow down-type intensive baking room; B. External circulation: When the axial flow fan is running in the forward direction, close the return air damper, open the cold air inlet door, and the outside air flows into the heating chamber through the cold air inlet door, then enters the smoke loading chamber from the air outlet at the upper end of the partition wall, and is discharged from the dense baking room through the dehumidification window; C. Internal and external circulation: When the axial flow fan is running in the forward direction, the return air damper is partially opened and the cold air inlet door is partially opened. The outside air flows into the heating chamber through the cold air inlet door, and enters the smoke loading chamber through the air outlet after being heated. Part of the air flows out of the air flow descending intensive baking room through the dehumidification window, and the other part of the air flows back to the heating chamber from the return air outlet to be heated again.

2. IV. Loading cigarettes: When picking tobacco leaves on rainy days, the amount of tobacco braided on a single tobacco rod should be reduced by 10% to 20% under normal weather conditions, with 130 to 140 pieces / rod; the amount of tobacco loaded in a single airflow-down intensive curing room should be reduced by 10% to 20%, with 320 to 340 rods / curing; after braiding, the tobacco rods should be hung on the hanging rack outside the airflow-down intensive curing room for 2h to 4h and drained appropriately; Ⅴ. Baking: Step 1: When picking and curing tobacco leaves on rainy days, the method of loading and igniting tobacco leaves is adopted to promote the temperature of the airflow descending intensive curing room to quickly increase to about 30℃; before ignition, set the temperature control point on the automatic controller; after ignition, the dry bulb temperature and wet bulb temperature are synchronously raised to 36℃ / 36℃ at a rate of 1℃ / h, and the temperature is stabilized for 3h~4h until the whole flue-cured tobacco leaves expand and sweat, and then the temperature begins to rise; before the dry bulb temperature is 30℃, turn on the reverse forward and reverse switch, the axial flow fan reverses at high speed, and the airflow circulates inside and outside; in the temperature range of 30℃~36℃, turn on the reverse forward and reverse switch, the axial flow fan reverses at low speed, and the airflow circulates inside; Step 2: After the 36℃ temperature stabilization is completed, the dry-bulb temperature and wet-bulb temperature are raised to 38℃ / 38℃ at a rate of 1℃ / h for 2h. During this period, the reverse and forward switches are turned on, the axial flow fan is reversed at a low speed, and the airflow circulates internally; then the forward and reverse switches are turned on, the axial flow fan is forward at a low speed, and low-speed forward rotation for 4h to dehumidify, the airflow circulates inside and outside, and then switched to low-speed reverse rotation, the dry and wet bulbs are kept at 38℃ / 36℃ for 4h, the airflow circulates inside and outside, and then switched to reverse rotation of the forward and reverse switches, the fan is reversed at a low speed, the dry and wet bulbs are kept at 38℃ / 36℃ for 4h, the airflow circulates inside and outside, and then switched to reverse rotation of the forward and reverse switches, the fan is reversed at a low speed, the dry and wet bulbs are kept at 38℃ / 36℃ for 4h, the airflow circulates inside and outside, and this is repeated until the middle tobacco leaves turn 70% to 80% yellow and the leaves become soft, and then the next step of baking is entered; Step 3: Raise the dry-bulb and wet-bulb temperatures to a steady 40°C / 37°C at a rate of 0.5°C / h until the middle tobacco leaves turn 80% to 90% yellow and most of the leaves wither and collapse, and then proceed to the next baking step; during this period, the axial flow fan performs sinusoidal forward and reverse rotation according to the cycle; When the dry-bulb temperature is between 30℃ and 40℃, the axial flow fan is subjected to sinusoidal forward and reverse rotation. From the time of ignition to the time of 30℃ dry-bulb temperature, the axial flow fan is reversed at high speed, and the airflow circulates inside and outside. From 30℃ to 36℃, the axial flow fan is reversed at low speed, and the airflow circulates inside. From 36℃ to 40℃ dry-bulb temperature, the axial flow fan is reversed at low speed, and the forward and reverse conversion frequency of the axial flow fan is 4h. A forward-reverse switch is used. After ignition, the forward-reverse switch is turned on to start the axial flow fan. The high speed gear of the axial flow fan is switched to high speed until the dry-bulb temperature rises to 30℃ / 30℃. After that, the axial flow fan is switched to low speed and runs for 4 hours. Then, the forward and reverse switch is turned on. The axial flow fan rotates forward at low speed. After running for another 4 hours, the reverse switch is turned on. The axial flow fan is switched to low speed and reverses. One forward and reverse sinusoidal cycle is completed. Then, the same sinusoidal cycle is switched until the dry-bulb temperature reaches 40℃ and the forward and reverse switching operation of the axial flow fan is terminated. The conversion process is carried out for a total of 24h to 38h. Step 4: Raise the dry-bulb and wet-bulb temperatures to a steady 42℃ / 36℃ at a rate of 0.5℃ / h until 30%-50% of the tobacco leaves in the middle layer have slightly hooked tips, and the tobacco leaves in the low-temperature layer turn 90% yellow and the main veins become soft and completely wither and collapse before entering the next step of baking; during this period, the axial flow fan runs in the forward direction, and the high and low speed gears are flexibly switched according to the wet-bulb temperature in the airflow descending intensive baking room, with the high speed gear as the main gear, the airflow circulates inside and outside, and the return air damper is closed by 1 / 2 to 2 / 3; Step 5: Raise the dry-bulb temperature to 45℃ / 37℃ at a rate of 0.3℃~0.4℃ / h, keep the temperature steady for 4h~6h, then raise the dry-bulb temperature to 48℃ / 37℃~38℃ at a rate of 0.3℃~0.4℃ / h, keep the temperature steady until the middle layer of tobacco leaves have yellow flakes and yellow tendons, and most of the tobacco leaves are small rolls, then raise the dry-bulb temperature to 51℃ / 39℃ at a rate of 0.5℃ / h, keep the temperature steady for 4h~6h, then raise the dry-bulb temperature to 54℃ / 40℃ at a rate of 0.5℃~0.67℃ / h, keep the temperature steady until the low temperature layer of tobacco leaves are large rolls; Step 6: Raise the dry-bulb and wet-bulb temperatures to a steady state of 60°C / 41°C at a rate of 1°C / h. When 2 / 3 of the main veins of the whole-cured tobacco leaves are dry, raise the dry-bulb and wet-bulb temperatures to a steady state of 65°C-67°C / 41°C-42°C at a rate of 0.5°C / h. Stop heating when the main veins of the whole-cured tobacco leaves are completely dry, and the curing is completed.

3. The method for curing tobacco leaves for rainy day curing according to claim 1, characterized in that: In step V. the first step of baking, in order to prevent the tobacco leaves in the low-temperature layer from sticking, before the dry-bulb temperature reaches 30°C after ignition, the axial flow fan is reversed at high speed and the air flow is circulated inside and outside to swing the tobacco leaves in the low-temperature layer through high-speed wind, shaking the tobacco leaves and shaking off some of the visible water on the surface of the tobacco leaves.

4. The method for curing tobacco leaves for rainy day curing according to claim 1, characterized in that: In step V. the first step of baking, in the temperature range of 30°C to 36°C, the axial flow fan is reversed at a low speed, and the air flow circulates internally, which can promote the increase of the temperature of the tobacco leaves in the low-temperature layer. At the same time, the internal circulation of the air flow can reduce the temperature difference between the upper and lower layers in the tobacco loading room. Moreover, since the tips of the tobacco leaves are slowly heated by the wind first, the greening caused by the long-term heating of the base of the tobacco leaves by the wind can be avoided.

5. The method for curing tobacco leaves for rainy day curing according to claim 1, characterized in that: In step V. the second and third steps of baking, when the dry bulb temperature is in the heating and stabilization stages of 36°C to 40°C, the axial flow fan is switched between forward and reverse every 4 hours, which can take into account the heating and wind conditions of the upper and lower layers of the tobacco leaves in the loading chamber of the airflow descending intensive curing room. At the same time, due to the continuous switching of the airflow direction in the loading chamber, the water on the surface of the tobacco leaves can be gradually shaken off, and the temperatures of the upper and lower layers in the loading chamber tend to be uniform, so as to solve the problem of tobacco leaves being harvested and cured in rainy weather, the upper layer of the tobacco leaves in the loading chamber of the airflow descending intensive curing room being in a state of high temperature and low humidity for a long time, while the lower layer of the tobacco leaves in the loading chamber being in a state of low temperature and high humidity for a long time, thereby promoting the coordination of yellowing and water loss of the upper and lower layers of the tobacco leaves in the loading chamber, reducing the appearance of green roasted leaves on the upper layer and thin roasted dregs on the lower layer, improving the baking quality and uniformity of tobacco leaves, and coping with the heating and dehumidification pressure and baking risks faced by tobacco leaves harvested and cured on rainy days.

6. The method for curing tobacco leaves harvested and cured on rainy days according to claim 1, characterized in that: In step V. the second step of baking, regarding air flow circulation: ignite while loading tobacco leaves. After loading and baking, the axial flow fan first rotates forward at high speed for 30 minutes, and the air flow circulates outside. Then it switches to reverse and runs at high speed for 30 minutes. The air flow circulates inside and outside until the dry bulb temperature reaches 30°C. At a relatively low temperature, the clear water on the surface of the tobacco leaves can be gradually shaken off to reduce tobacco leaf adhesion.

7. The method for curing tobacco leaves harvested and cured on rainy days according to claim 1, characterized in that: In step V. of the fifth step of baking, regarding the dry-bulb temperature point: the dry-bulb temperature is staged at 45°C, 48°C, 51°C and 54°C for temperature increase and stabilization, and the dry-bulb temperature points are evenly distributed. In the tobacco loading room of the airflow-down intensive baking room, the temperature of the lower layer of tobacco leaves in the tobacco loading room can be gradually increased, and the yellowing and water loss of the lower layer of tobacco leaves can be coordinated, and the shrinkage and rolling of tobacco leaves can be promoted, and the occurrence of smoothness on both sides and the base of the main veins of tobacco leaves can be reduced, thereby improving the baking quality of tobacco leaves.

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