Tobacco leaf curing method for box type curing barn

Abstract

The invention discloses a tobacco leaf curing method for a box-type curing barn. The tobacco leaf curing method solves the problems that in the prior art, a curing method of a box-type curing barn is indefinite in index, large in curing difficulty and long in curing time. The new tobacco leaves are baked after being harvested, and the baking method comprises a yellowing and softening stage, a yellowing and collapsing stage, a drying and delaminating stage, a drying sufficient stage, a drying and vein shrinking stage, a drying and vein fixing stage and an air-drying and fragrance overflowing stage. According to the method, the baking environment parameters of each stage in the baking process of the box-type baking room and the corresponding tobacco leaf state judgment indexes are defined, the baking difficulty of the box-type baking room is reduced, and baking personnel can master the baking technology of the box-type baking room more quickly.

Description

Technical Field

[0001] The invention relates to the technical field of tobacco leaf baking, in particular to a tobacco leaf baking method. Background Art

[0002] Box-type baking fundamentally reduces labor intensity with its mechanized harvesting, loading, and putting on the kang. Although box-type baking rooms have achieved certain advantages in production, due to the high density of tobacco loading in box-type baking rooms, the source of heat inside the box is mainly heat transfer and heat radiation, while the most effective way to obtain heat for tobacco baking is heat convection. However, due to the limitations of the box-type baking loading method, the amount of heat convection obtained inside the box is very small, resulting in a large amount of black and stale tobacco leaves after baking, which seriously restricts the promotion and application of box-type baking in tobacco producing areas across the country.

[0003] Compared with the current intensive curing room, the proportion of tobacco leaves that can be observed in the box-type curing room during the curing process is very small, which makes the accuracy of the judgment of the curing status of tobacco leaves during box-type curing increasingly poor, and at the same time causes greater psychological pressure on the curing personnel. Under the superposition of the two, the curing difficulty of box-type curing is increasing. In addition, due to the difference in the way of loading tobacco in box-type curing rooms and intensive curing rooms, the current box-type curing is mostly carried out by completely copying the judgment indicators of the tobacco leaf status in the intensive curing room, which cannot complete the curing of the box-type curing room. Therefore, it is urgent to formulate a set of matching curing processes and judgment indicators for the current box-type curing rooms. Summary of the invention

[0004] In view of the deficiencies in the above-mentioned background technology, the present invention proposes a tobacco leaf baking method for a box-type baking barn, which solves the problems of unclear indicators, great baking difficulty and long baking time in the box-type baking barn baking method in the prior art.

[0005] The technical solution of the present invention is achieved as follows: a tobacco leaf baking method for a box-type baking room, wherein new tobacco leaves are harvested and loaded into a tobacco baking box, and the tobacco baking box is loaded into the baking room for baking, and the baking process includes a yellowing and softening stage, a yellowing and collapsing stage, a drying and separation stage, a sufficient drying stage, a drying and shrinking vein stage, a drying and fixing vein stage, and an air-drying and fragrant stage.

[0006] It is further preferred that the fresh leaves are packed in boxes after being harvested, and at least ten tobacco curing boxes are arranged in each curing room, each of which contains 445-455 kg of lower leaves, 475-485 kg of middle leaves, or 515-525 kg of upper leaves; two groups of temperature and humidity sensors are arranged in the tobacco curing box, the upper temperature and humidity sensor is arranged at 14.5-15.5 cm from the top of the box, and the lower temperature and humidity sensor is arranged at 14.5-15.5 cm from the bottom of the box, and the dry-bulb temperature and the wet-bulb temperature both use the measurement data of the temperature and humidity sensor located at the lower part.

[0007] It is further preferred that, in the yellowing and softening stage, the dry-bulb temperature is raised to 39.5-40.5°C and the wet-bulb temperature is raised to 37.5-38.5°C within 1-2 hours, and the temperature is maintained stable for 24 hours. After the tobacco leaves in the front and rear observation windows of the curing room have completely turned yellow, the dry-bulb temperature is kept unchanged, the wet-bulb temperature is lowered to 35.5-36.5°C, and the temperature is maintained stable for 10-15 hours, until the tobacco leaves on the top layer of the box turn 90% yellow and the leaf tips become soft.

[0008] It is further preferred that, in the yellowing and collapsing stage, after the yellowing and softening stage is completed, the dry bulb temperature is raised to 42.5-43.5°C at a rate of 0.5°C / h, the wet bulb temperature is reduced to 34.5-35.5°C, the fan is operated at high speed, and the temperature is stabilized for 15-20 hours.

[0009] It is further preferred that, in the sufficient drying stage, after the yellowing and collapse stage is completed, the dry-bulb temperature is raised to 45.5-46.5°C at a rate of 0.33°C / h, the wet-bulb temperature is maintained at 34.5-35.5°C, the fan is operated at high speed, the temperature is maintained stable for 15-18 hours, the tobacco leaves on both sides of the box are dried and shrunk and form a separation layer with the iron plates on both sides, and the separation layer thickness is 4-5 cm.

[0010] It is further preferred that, in the drying and delamination stage, after the sufficient drying stage is completed, the dry bulb temperature is raised to 47.5-48.5°C at a rate of 0.33°C / h, the wet bulb temperature is maintained at 35°C, the fan is operated at high speed, and the temperature is maintained at a stable level for 12h-15h.

[0011] It is further preferred that, in the drying and vein shrinking stage, after the drying and absorptive stage is completed, the dry bulb temperature is raised to 51.5-52.5°C at a rate of 0.5°C / h, the wet bulb temperature is raised to 35.5-36.5°C, the fan is operated at high speed, the temperature is maintained stable for 10-15 hours, and 1 / 2 of the leaf tip to petiole is dried.

[0012] It is further preferred that, in the drying pulse setting stage, after the drying pulse shrinking stage is completed, the dry bulb temperature is raised to 54.5-55.5°C at a rate of 1°C / h, the wet bulb temperature is raised to 36.5-37.5°C, the fan is operated at high speed, and the temperature is stabilized for 12 hours.

[0013] It is further preferred that, in the air-drying and aroma-emitting stage, after the drying and pulse setting stage is completed, the dry-bulb temperature is raised to 59.5-60.5°C at a rate of 1°C / h, the wet-bulb temperature is raised to 37.5-38.5°C, the fan is operated at a low speed, and the temperature is maintained stable for 8-10 hours, the dry-bulb temperature is raised to 64.5-65.5°C at a rate of 1°C / h, the wet-bulb temperature is raised to 38.5-39.5°C, and the temperature is maintained stable for 24 hours to 30 hours.

[0014] It is further preferred that, during the air-drying and aroma-emitting stage, when the data on the temperature and humidity sensor located at the upper part of the oven is consistent with the data on the temperature and humidity sensor located at the lower part, the tobacco leaf baking is completed.

[0015] The beneficial effects of the present invention are:

[0016] The present invention clarifies the baking environment parameters and corresponding tobacco leaf status judgment indicators at each stage of the baking process in the box-type baking room by arranging two upper and lower temperature and humidity sensors in the oven, thereby reducing the baking difficulty of the box-type baking room and allowing baking personnel to master the baking technology of the box-type baking room more quickly; it effectively solves the problems of unclear indicators, great baking difficulty and long baking time in the existing box-type baking room baking method.

[0017] In terms of tobacco leaf baking status judgment indicators, based on traditional visual judgment, two temperature and humidity sensors are used as baking indicators to solve the problem that tobacco leaves inside the box cannot be observed during baking, and the baking status is clarified;

[0018] The present invention adopts high temperature and medium humidity yellowing (40 / 38°C), which not only increases the temperature outside the box but also increases the temperature of the tobacco leaves inside the box, providing heat for the smooth yellowing of the tobacco leaves inside the box.

[0019] During the leaf drying process, a multi-stage moist drying method is adopted to ensure that the tobacco leaves inside the box are dried smoothly and the quality of the tobacco leaves is guaranteed. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1

[0022] A tobacco leaf baking method for a box-type baking house comprises the following steps: after tobacco leaves at different positions reach a mature harvesting standard, the harvested tobacco leaves are loaded into a tobacco baking box, and the tobacco baking box is loaded into the baking house for baking, and the baking process comprises a yellowing and softening stage, a yellowing and collapsing stage, a drying and separation stage, a sufficient drying stage, a drying and shrinking vein stage, a drying and fixing vein stage, and an air-drying and fragrant stage.

[0023] After the fresh leaves are harvested, they are loaded into tobacco curing boxes. At least ten tobacco curing boxes are arranged in each curing room, and each tobacco curing box contains 445-455 kg of lower leaves, 475-485 kg of middle leaves, or 515-525 kg of upper leaves. Preferably, when the lower leaves are placed in the tobacco curing box, the weight of the lower leaves is 450 kg, when the middle leaves are placed in the tobacco curing box, the weight of the middle leaves is selected to be 480 kg, and when the upper leaves are placed in the oven, the weight of the upper leaves is 520 kg. Two groups of temperature and humidity sensors are provided in the tobacco curing box. The upper temperature and humidity sensor is arranged at a distance of 14.5 to 15.5 cm from the top of the box. Preferably, the distance between the upper temperature and humidity sensor and the top of the box is 15 cm. The lower temperature and humidity sensor is arranged at a distance of 14.5 to 15.5 cm from the bottom of the box. Preferably, the distance between the lower temperature and humidity sensor and the bottom of the box is 15 cm. During the baking stage, the data for observing the dry-bulb temperature and the wet-bulb temperature in the tobacco curing box are all measured by the temperature and humidity sensor located at the lower part.

[0024] During the yellowing and softening stage, the dry bulb temperature is raised to 40°C and the wet bulb temperature is raised to 38°C within 1 to 2 hours, and the temperature is maintained stable for 24 hours. After the tobacco leaves in the front and rear observation windows of the curing room have completely turned yellow, the dry bulb temperature is kept unchanged, the wet bulb temperature is lowered to 36°C, and the temperature is maintained stable for 10 to 15 hours, until the tobacco leaves on the top layer of the box turn 90% yellow and the leaf tips become soft.

[0025] In the yellowing and collapsing stage, after the yellowing and softening stage is completed, the dry bulb temperature is raised to 43°C at a rate of 0.5°C / h, the wet bulb temperature is reduced to 35°C, the fan is operated at high speed, and the temperature is stabilized for 15 to 20 hours.

[0026] In the sufficient drying stage, after the yellowing and collapse stage is completed, the dry bulb temperature is raised to 46°C at a rate of 0.33°C / h, the wet bulb temperature is maintained at 35°C, the fan is operated at high speed, and the temperature is maintained stable for 15 to 18 hours. The tobacco leaves on both sides of the box dry and shrink and form a separation layer with the iron plates on both sides, and the separation layer thickness is 4 to 5 cm.

[0027] In the drying and delamination stage, after the full drying stage is completed, the dry bulb temperature is raised to 48°C at a rate of 0.33°C / h, the wet bulb temperature is maintained at 35°C, the fan is operated at high speed, and the temperature is stabilized for 12h to 15h.

[0028] In the drying and vein shrinking stage, after the drying and absorptive stage is completed, the dry bulb temperature is raised to 52°C at a rate of 0.5°C / h, the wet bulb temperature is raised to 36°C, the fan is operated at high speed, the temperature is kept stable for 10 to 15 hours, and 1 / 2 of the leaf tip to petiole is dried.

[0029] In the drying pulse setting stage, after the drying pulse shrinking stage is completed, the dry bulb temperature is raised to 55°C and the wet bulb temperature is raised to 37°C at a rate of 1°C / h, the fan is operated at high speed, and the temperature is stabilized for 12 hours.

[0030] In the air-drying and aroma-emitting stage, after the drying and pulse setting stage is completed, the dry-bulb temperature is raised to 60°C and the wet-bulb temperature is raised to 38°C at a rate of 1°C / h, the fan is operated at a low speed, and the temperature is maintained stable for 8h to 10h, the dry-bulb temperature is raised to 65°C and the wet-bulb temperature is raised to 39°C at a rate of 1°C / h, and the temperature is maintained stable for 24h to 30h.

[0031] In the air-drying and fragrance-filled stage, when the data on the temperature and humidity sensor located at the upper part of the oven is consistent with the data on the temperature and humidity sensor located at the lower part, the tobacco leaf baking is completed. At this time, the gas discharged through the dehumidification window of the baking room is completely dry, and the tobacco fragrance can be smelled, which reduces the tobacco leaf baking time. In addition, the use of two temperature and humidity sensors as evaluation criteria can solve the problem that the baking process in the baking room takes a long time and the baking status of the tobacco leaves in the baking box cannot be observed. In addition, the use of two temperature and humidity sensors as evaluation criteria clarifies the baking indicators and reduces the difficulty of baking.

[0032] Example 2

[0033] After tobacco leaves at different positions reach the mature harvesting standard, tobacco leaves are harvested by tobacco leaf harvesters respectively, and loaded with supporting box-type baking equipment. Each baking room can accommodate 10 boxes, and the fresh tobacco loading capacity of each box is 450kg for lower leaves, 480kg for middle leaves, or 520kg for upper leaves. Baking is carried out according to the baking process of the present invention. Since the quality of fresh tobacco and the loading quantity of tobacco leaves at different positions are different, the temperature stabilization time in each stage is different.

[0034] Yellowing and softening stage

[0035] After loading, seal the outermost box of the curing room with a sponge strip, then close the door of the curing room, ignite, and run the circulating fan at a low speed. Raise the dry-bulb temperature to 40°C and the wet-bulb temperature to 38°C within 1 to 2 hours. Keep the temperature steady for 24 hours. After the tobacco leaves in the front and rear observation windows of the curing room turn completely yellow, keep the dry-bulb temperature unchanged, drop the wet-bulb temperature to 36°C, and keep the temperature steady for 10 to 15 hours, until the tobacco leaves on the top layer of the box turn 90% yellow and the leaf tips become soft.

[0036] Yellowing and collapse stage

[0037] After the yellowing and softening stage is completed, the dry bulb temperature is raised to 43°C at a rate of 0.5°C / h, the wet bulb temperature is reduced to 35°C, the fan is operated at high speed, and the temperature is maintained stable for 15 to 20 hours, so that the tobacco leaves on the top layer of the box turn completely yellow, and all the tobacco leaves wither and collapse to about 10 cm away from the top frame of the box.

[0038] Full drying stage

[0039] After the yellowing and collapse stage is completed, the dry bulb temperature is raised to 46°C at a rate of 0.33°C / h, the wet bulb temperature is maintained at 35°C, the fan is operated at high speed, and the temperature is maintained stable for 15 to 18 hours to completely dry the tobacco leaves on the top layer of the box and at the front and rear observation windows of the curing room.

[0040] Drying separation stage

[0041] After the full drying stage is completed, the dry bulb temperature is raised to 48°C at a rate of 0.33°C / h, the wet bulb temperature is maintained at 35°C, the fan is operated at high speed, and the temperature is maintained stable for 12 to 15 hours, so that the tobacco leaves on both sides of the box are completely dried and shrunk, and a separation layer is formed with the iron plates on both sides, with a thickness of 4 to 5 cm.

[0042] Dry vein shrinkage stage

[0043] After the drying and delamination stage is completed, the dry bulb temperature is raised to 52℃ and the wet bulb temperature is raised to 36℃ at a rate of 0.5℃ / h. The fan is operated at high speed and the temperature is kept stable for 10 to 15 hours to completely dry the branch veins of the tobacco leaves on the top layer of the box and the front and rear observation windows of the curing room, and the main vein at the petiole is obviously contracted, and 1 / 2 of the leaf tip to the petiole is dry.

[0044] Drying and venation stage

[0045] After the drying pulse shrinkage stage is completed, the dry bulb temperature is raised to 55°C at a rate of 1°C / h, and the wet bulb temperature is raised to 37°C. The fan is operated at high speed and the temperature is kept stable for 12 hours to completely dry and fix the main veins of the tobacco leaves on the top layer of the box and the front and rear observation windows of the curing room.

[0046] Air-drying and fragrant stage

[0047] After the drying and pulsing stage is completed, the dry-bulb temperature is raised to 60℃ and the wet-bulb temperature is raised to 38℃ at a rate of 1℃ / h. The fan is operated at a low speed and the temperature is stabilized for 8 to 10 hours until the gas discharged from the dehumidification window of the curing room is completely dry and the data of the two sets of temperature and humidity sensors are consistent. The dry-bulb temperature is raised to 65℃ and the wet-bulb temperature is raised to 39℃ at a rate of 1℃ / h. The fan is operated at a low speed and the temperature is stabilized for 24 to 30 hours. The gas discharged from the dehumidification window of the curing room is completely dry and the smoke aroma can be smelled. The data of the two sets of temperature and humidity sensors are consistent, and the tobacco baking is completed.

[0048] Example 3

[0049] The verification test was conducted in Kuzhuang Town, Xiangcheng County, Xuchang City, Henan Province in 2023, and the test flue-cured tobacco variety was Y2001. The test tobacco leaves were cultivated and managed in accordance with the standardized production of local high-quality tobacco leaves, and harvested according to the maturity standard. The test tobacco leaves were lower leaves, and the test curing room was a box-type curing room, with a fresh tobacco loading capacity of 4500kg.

[0050] Experimental design

[0051] A comparative test was carried out using the local main baking process as a control and the baking process of the present invention as a treatment.

[0052] Table 1 Experimental design

[0053]

[0054] Cost-effectiveness evaluation of late tobacco leaves

[0055] The time and power consumption of different baking processes were counted, and one box was randomly selected. The tobacco leaves in the box were graded and weighed according to the national standard of 42 grades. The fresh-to-dry ratio of tobacco leaves with different treatments was calculated based on the weight of fresh tobacco.

[0056] Table 2 Cost effect of flue-cured tobacco leaves

[0057]

[0058] Table 2 is a comparison of the cost-effectiveness of tobacco leaves after being cured by different curing processes. It can be seen that the proportion of upper-middle grade tobacco leaves by the curing process of the present invention is 10.4 percentage points higher than that of the local curing process, the proportion of lower grade tobacco leaves is 9.2 percentage points lower, the proportion of ungraded tobacco leaves is 0.4 percentage points lower, and the fresh-to-dry ratio is 0.3 percentage points lower. It can be seen that the weight of dry tobacco leaves after being cured by the curing process of the present invention is higher, the entire curing process saves 21.3 hours of time, and 106.4 degrees of electricity.

[0059] Comparison of appearance quality of flue-cured tobacco leaves

[0060] Table 3 Appearance quality scores of flue-cured tobacco leaves

[0061]

[0062] As shown in Table 3, the appearance quality evaluation of the flue-cured tobacco leaves showed that, compared with the local flue-curing process, the leaf structure score of this flue-curing process increased by 1 point, the identity score increased by 1 point, and the maturity score increased by 0.5 point.

[0063] Example 4

[0064] The verification test was conducted in Kuzhuang Town, Xiangcheng County, Xuchang City, Henan Province in 2023, and the test flue-cured tobacco variety was Y2001. The test tobacco leaves were cultivated and managed in accordance with the standardized production of local high-quality tobacco leaves, and harvested according to the maturity standard. The test tobacco leaves were in the middle leaves, and the test curing room was a box-type curing room, with a fresh tobacco loading capacity of 4800kg.

[0065] Experimental design

[0066] A comparative test was carried out using the local main baking process as a control and this baking process as a treatment.

[0067] Table 4 Experimental design

[0068]

[0069] Cost-effectiveness evaluation of flue-cured tobacco leaves

[0070] The time and power consumption of different baking processes were counted, and one box was randomly selected. The tobacco leaves in the box were graded and weighed according to the national standard of 42 grades. The fresh-to-dry ratio of tobacco leaves with different treatments was calculated based on the weight of fresh tobacco.

[0071] Table 5 Cost effect of flue-cured tobacco leaves

[0072]

[0073] Table 5 is a comparison of the cost-effectiveness of tobacco leaves after being cured by different curing processes. It can be seen that the proportion of upper-middle tobacco in the middle leaves of the curing process of the present invention is 4.2 percentage points higher than that of the local curing process, the proportion of lower-grade tobacco is 1.5 percentage points lower, the proportion of ungraded tobacco is 2.7 percentage points lower, and the fresh-to-dry ratio is 0.15 percentage points lower. It can be seen that the weight of dry tobacco after being cured by the curing process of the present invention is higher, the whole curing process saves 21.8 hours of time and 127.7 degrees of electricity.

[0074] Comparison of appearance quality of flue-cured tobacco leaves

[0075] Table 6 Appearance quality scores of flue-cured tobacco leaves

[0076]

[0077] As shown in Table 6, the appearance quality evaluation of the cured tobacco leaves shows that, compared with the local curing process, the color score of the cured tobacco leaves by the curing process of the present invention is increased by 0.5 points, the leaf structure score is increased by 1 point, the oil score is increased by 0.5 points, and the maturity score is increased by 0.5 points.

[0078] Example 5

[0079] The verification test was conducted in Kuzhuang Town, Xiangcheng County, Xuchang City, Henan Province in 2023, and the test flue-cured tobacco variety was Y2001. The test tobacco leaves were cultivated and managed in accordance with the standardized production of local high-quality tobacco leaves, and harvested according to the maturity standard. The test tobacco leaves were upper leaves, and the test curing room was a box-type curing room. The fresh tobacco loading capacity was 5200kg.

[0080] Experimental design

[0081] A comparative test was carried out using the local main baking process as a control and the baking process of the present invention as a treatment.

[0082] Table 7 Experimental design

[0083]

[0084] Cost-effectiveness evaluation of flue-cured tobacco leaves

[0085] The time and power consumption of different baking processes were counted, and one box was randomly selected. The tobacco leaves in the box were graded and weighed according to the national standard of 42 grades. The fresh-to-dry ratio of tobacco leaves with different treatments was calculated based on the weight of fresh tobacco.

[0086] Table 8 Cost effect of flue-cured tobacco leaves

[0087]

[0088] Table 8 is a comparison of the cost-effectiveness of tobacco leaves after being cured by different curing processes. It can be seen that the proportion of upper and middle-grade tobacco leaves by the curing process of the present invention is 5.6 percentage points higher than that of the local curing process, the proportion of lower-grade tobacco leaves is 2.2 percentage points lower, the proportion of ungraded tobacco leaves is 3.4 percentage points lower, and the fresh-to-dry ratio is 0.5 percentage points lower. It can be seen that the weight of dry tobacco leaves after being cured by the curing process of the present invention is higher, the entire curing process saves 27.9 hours of time, and saves 144.8 degrees of electricity.

[0089] Comparison of appearance quality of flue-cured tobacco leaves

[0090] Table 9 Appearance quality scores of flue-cured tobacco leaves

[0091]

[0092] As can be seen from Table 9, the appearance quality evaluation of the cured tobacco leaves shows that, compared with the local curing process, the leaf structure score of the curing process of the present invention is increased by 0.5 points, the chromaticity score is increased by 0.5 points, and the maturity score is increased by 1 point.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A tobacco leaf baking method for a box-type baking barn, wherein new tobacco leaves are harvested and loaded into a tobacco baking box, and the tobacco baking box is loaded into the baking barn for baking, characterized in that: The baking process includes the yellowing and softening stage, the yellowing and collapsing stage, the drying and delamination stage, the complete drying stage, the drying and shrinking vein stage, the drying and fixing vein stage, and the air-drying and fragrant stage.

2. The tobacco leaf baking method for a box-type baking barn according to claim 1, characterized in that: The fresh leaves are packed after harvesting, and at least ten tobacco curing boxes are arranged in each curing room, and each tobacco curing box is placed with 445-455 kg of lower leaves, 475-485 kg of middle leaves, or 515-525 kg of upper leaves; two groups of temperature and humidity sensors are arranged in the tobacco curing box, the upper temperature and humidity sensor is set at 14.5-15.5 cm from the top of the box, and the lower temperature and humidity sensor is set at 14.5-15.5 cm from the bottom of the box, and the dry-bulb temperature and the wet-bulb temperature are both measured by the temperature and humidity sensor located at the lower part.

3. The tobacco leaf baking method for a box-type baking barn according to claim 2, characterized in that: During the yellowing and softening stage, the dry-bulb temperature is raised to 39.5-40.5°C and the wet-bulb temperature is raised to 37.5-38.5°C within 1-2 hours, and the temperature is kept stable for 24 hours. After the tobacco leaves in the front and rear observation windows of the curing room have completely turned yellow, the dry-bulb temperature is kept unchanged, and the wet-bulb temperature is lowered to 35.5-36.5°C and the temperature is kept stable for 10-15 hours, until the tobacco leaves on the top layer of the box turn 90% yellow and the leaf tips become soft.

4. The tobacco leaf baking method for a box-type baking barn according to claim 3, characterized in that: During the yellowing and collapsing stage, after the yellowing and softening stage is completed, the dry bulb temperature is raised to 42.5-43.5°C at a rate of 0.5°C / h, the wet bulb temperature is reduced to 34.5-35.5°C, the fan is operated at high speed, and the temperature is stabilized for 15-20 hours.

5. The tobacco leaf baking method for a box-type baking barn according to claim 4, characterized in that: In the described sufficient drying stage, after the yellowing and collapse stage is completed, the dry-bulb temperature is raised to 45.5-46.5°C at a rate of 0.33°C / h, the wet-bulb temperature is maintained at 34.5-35.5°C, the fan is operated at high speed, and the temperature is kept stable for 15-18 hours. The tobacco leaves on both sides of the box dry and shrink and form a separation layer with the iron plates on both sides, and the thickness of the separation layer is 4-5 cm.

6. The tobacco leaf baking method for a box-type baking barn according to claim 5, characterized in that: In the drying and delamination stage, after the full drying stage is completed, the dry bulb temperature is raised to 47.5-48.5°C at a rate of 0.33°C / h, the wet bulb temperature is maintained at 35°C, the fan is operated at high speed, and the temperature is stabilized for 12h-15h.

7. The tobacco leaf baking method for a box-type baking barn according to claim 6, characterized in that: In the drying and vein shrinking stage, after the drying and absorptive stage is completed, the dry bulb temperature is raised to 51.5-52.5°C at a rate of 0.5°C / h, the wet bulb temperature is raised to 35.5-36.5°C, the fan is operated at high speed, the temperature is kept stable for 10-15 hours, and 1 / 2 of the leaf tip to petiole is dried.

8. The tobacco leaf baking method for a box-type baking barn according to claim 7, characterized in that: In the drying pulse setting stage, after the drying pulse shrinking stage is completed, the dry bulb temperature is raised to 54.5-55.5°C at a rate of 1°C / h, the wet bulb temperature is raised to 36.5-37.5°C, the fan is operated at high speed, and the temperature is stabilized for 12 hours.

9. The tobacco leaf baking method for a box-type baking barn according to claim 8, characterized in that: In the air-drying and aroma-filled stage, after the drying and pulse setting stage is completed, the dry-bulb temperature is raised to 59.5-60.5°C at a rate of 1°C / h, the wet-bulb temperature is raised to 37.5-38.5°C, the fan is operated at a low speed, and the temperature is maintained stable for 8-10 hours. In the air-drying and aroma-filled stage, the dry-bulb temperature is raised to 64.5-65.5°C at a rate of 1°C / h, the wet-bulb temperature is raised to 38.5-39.5°C, and the temperature is maintained stable for 24-30 hours.

10. The tobacco leaf baking method for a box-type baking barn according to claim 9, characterized in that: During the air-drying and aroma-filled stage, when the data on the temperature and humidity sensor located at the upper part of the oven is consistent with the data on the temperature and humidity sensor located at the lower part, the tobacco leaf baking is completed.

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