Energy-saving and moisture-recovering process of tobacco sheet re-drying machine for threshing and redrying

Abstract

The application discloses a tobacco leaf redrying process for energy saving of a tobacco leaf redrying machine for threshing and redrying, which comprises the following steps: 1) simultaneously performing hot air treatment and ultrasonic treatment on the stacked tobacco leaves at the end area of the joint of the drying section and the cooling section, the hot air treatment and the ultrasonic treatment being performed for 0.2-0.3 min, and the moisture content of the tobacco leaves after the treatment being 9-10%; 2) simultaneously performing air cooling treatment and ultrasonic treatment on the stacked tobacco leaves in the cooling section, the air cooling treatment and the ultrasonic treatment being performed for 0.2-0.3 min, and the temperature of the tobacco leaves after the treatment being controlled to be 25-30 DEG C; and 3) in the redrying section, using a pure steam and water mixed atomization mode, controlling the temperature to be 50-60 DEG C, controlling the relative humidity to be 85-95%, and after the treatment for 1.2-1.8 min, entering a cooling cutting section to reduce the temperature. The method can effectively shorten the redrying time, reduce the steam consumption in the redrying, and make the moisture content of the stacked tobacco leaves in the middle part, the top surface and the bottom surface uniform after the redrying, thereby effectively avoiding the problem of insufficient local redrying and making the moisture content of the top tobacco leaves uniform.

Description

TECHNICAL FIELD

[0001] The present application relates to the tobacco processing technology field, in particular to a tobacco sheet redrying machine energy-saving and moisture-regulating process for tobacco processing. BACKGROUND

[0002] As a key link in the tobacco industry chain, tobacco processing is responsible for deep processing of tobacco leaves classified by tobacco farmers. This process involves pretreatment, impurity separation, leaf and stem separation, tobacco sheet redrying, and packaging, etc. detailed procedures, aiming to convert raw tobacco agricultural products into industrialized tobacco raw materials that meet the requirements of the cigarette factory's silk line process. In the production process of tobacco processing, tobacco sheet redrying is very important. Through fine process control and treatment of tobacco sheets (referred to as tobacco sheets) after leaf and stem separation, not only can the inherent aroma of tobacco be effectively improved, and the harmful odor components be removed, but also the moisture content of tobacco sheets can be accurately adjusted, and potential insect eggs and mold can be killed, ensuring the quality and safety of tobacco sheets, and better adapting to storage and aging needs.

[0003] Currently, the tobacco industry widely uses tobacco sheet redrying machines with a net-belt box structure, with a design capacity of 9600 kg / h. The equipment is composed of three main process sections: drying section, cooling section, and moisture-regulating section, which are connected in series to form an efficient and continuous processing flow. Inside the equipment, the perforated conveying chain plate (i.e., the net belt) is used to lay the tobacco sheets on the net belt to form a certain thickness of the material layer and move forward at a stable speed. The tobacco sheets pass through the drying, cooling, and moisture-regulating stages in sequence, and are subjected to the precise action of circulating hot air, cold cutting wind, and humid hot air containing moisture and steam, respectively, to achieve the process goals of each stage.

[0004] Specifically, the drying section uses hot air to dry the tobacco sheets, accurately controlling the moisture content of the tobacco sheets within the critical range of bound water, usually with a moisture content of 9.0%-10.0% after baking. Then, the cooling section uses a fan to suck the air from the surrounding environment into the equipment to exchange heat with the tobacco sheets, reducing the temperature of the tobacco sheets to an appropriate temperature, preparing for the subsequent moisture-regulating process. Finally, in the moisture-regulating section, by adding an appropriate amount of atomized water and steam, the tobacco sheets are subjected to temperature and humidity increasing treatment, so that the moisture content of the tobacco sheets reaches about 12.0%, and the temperature is stabilized at about 45℃.

[0005] However, despite the maturity of the existing technology, the moisture-regulating process of the tobacco sheet redrying machine still has some shortcomings: the traditional moisture-regulating method mainly uses pure steam, steam-water mixture, and compressed air atomized water, which are uniformly applied to the surface of the tobacco leaves for temperature and humidity increasing. However, when the droplet size is large, the surface temperature is high, and the water content is low, the contact angle is large,

[0006] The wetting time is long, and a long processing time is required to achieve complete wetting of the stacked tobacco leaves. Meanwhile, the existing processing method also has a moisture recovery process. After the steam droplets are cooled and precipitated, the water droplets formed fall on the tobacco strips, causing uneven moisture of the tobacco strips after moisture recovery.

[0007] The tobacco leaves in the moisture recovery section have weak moisture recovery capacity, the wetting effect of the steam sprayed on the surface of the tobacco leaves is poor, the wetting time is long, and the wetting depth cannot meet the needs of subsequent production, making it difficult for the middle tobacco leaves to be completely moisture recovered. The existing method mainly prolongs the processing time and the amount of steam in the moisture recovery section, which further prolongs the moisture recovery operation time, wastes steam, and increases the production operation cost.

[0008] To solve the above problems, the existing processing method disclosed in CN202310085370.9 provides a moisture recovery method for high-end specialty tobacco leaves. The method realizes hot air and ultrasonic treatment of tobacco leaves in the moisture recovery process by arranging a hot air and ultrasonic treatment device in the moisture recovery section. Although this method can effectively shorten the moisture recovery time to less than 3 hours. However, this method is mainly suitable for moisture recovery houses, and in this method, the ultrasonic wave is only used to atomize water to obtain water droplets with smaller particle size to replace steam for moisture recovery. However, the moisture recovery time is still long, the moisture recovery efficiency is low, and the structure of the moisture recovery house limits the number of tobacco leaves processed in a single batch. Before the moisture recovery is completed, the tobacco leaves can be kept in the moisture recovery house without moving to the next process, which cannot realize continuous and large-scale moisture recovery of tobacco leaves. Therefore, this method is not suitable for tobacco strip redrying machines with a net belt box structure.

[0009] To solve the above problems, the method 202110164436.4 mainly uses ultrasonic atomization vacuum pre-moisture recovery to retain tobacco characteristic aroma substances at a lower temperature and a higher humidity. However, this method cannot effectively shorten the processing time and the amount of steam in the moisture recovery section of the tobacco strip redrying machine with a net belt box structure. SUMMARY

[0010] The present application provides an energy-saving moisture recovery process for a tobacco strip redrying machine for threshing and redrying. The method can effectively shorten the moisture recovery time, reduce the amount of steam used in the moisture recovery process, and make the moisture of the middle stacked tobacco strips uniform with that of the top and bottom tobacco leaves after moisture recovery. This can effectively avoid the problem of insufficient moisture recovery in some areas, and the moisture content of the top tobacco leaves in each area is uniform, and no local water accumulation occurs.

[0011] The present application provides an energy-saving moisture recovery process for a tobacco strip redrying machine for threshing and redrying. The tobacco strip redrying machine is a net belt box structure tobacco strip redrying machine, which includes a drying section, a cooling section, and a moisture recovery section. The method includes the following steps:

[0012] 1) in the end area of the drying section and the cooling section, the stacked tobacco sheets are simultaneously subjected to hot air treatment and ultrasonic treatment, the hot air treatment and the ultrasonic treatment are jointly processed for 0.2-0.3 min, and the moisture content of the tobacco sheets after processing is 9-10%;

[0013] 2) in the cooling section, the stacked tobacco sheets are simultaneously subjected to air cooling treatment and ultrasonic treatment, the air cooling treatment and the ultrasonic treatment are jointly processed for 0.2-0.3 min, and the temperature of the tobacco sheets after processing is controlled to be 25-30℃;

[0014] 3) in the moisture recovery section, pure steam and water atomized mixed method are adopted, the temperature is controlled to be 50-60℃, the relative humidity is controlled to be 85-95%, and after processing for 1.2-1.8 min, the temperature is reduced in the cold cutting section.

[0015] In the processing process, the tobacco sheets first enter the drying section to gradually dehydrate, and then enter the end section. In the end section, an ultrasonic wave generating device and a hot air pipe are simultaneously arranged for the tobacco sheets in the region, and the tobacco sheets are simultaneously subjected to ultrasonic waves and hot air. Under the joint action of the ultrasonic waves and the hot air, a rough surface required for later moisture recovery can be formed on the surface of the tobacco sheets, and a structure with strong water absorption can be formed in the tobacco sheets, so as to avoid the excessive tightness of the surface of the tobacco sheets affecting the infiltration of liquid drops in the later stage, and to obtain a good moisture recovery effect in the case of shortening the moisture recovery processing time. The pure steam and water atomized mixed method in the moisture recovery section refers to the gas obtained by atomizing the mixture of water and pure steam into the moisture recovery section.

[0016] Preferably, the ultrasonic frequency used in the ultrasonic treatment in step 1) is 30-50 kHz. The use of this frequency can obtain a better moisture recovery effect and shorten the moisture recovery processing time.

[0017] Preferably, when the processed tobacco sheets are upper tobacco leaves, the ultrasonic frequency used in the ultrasonic treatment in step 1) is 45 kHz; when the processed tobacco leaves are middle tobacco leaves, the ultrasonic frequency used in the ultrasonic treatment in step 1) is 30 kHz. According to the different harvesting positions of the processed tobacco leaves, the above-mentioned frequencies are used for ultrasonic treatment, which can more effectively improve the bulk moisture recovery processing effect of the tobacco leaves in different parts of the tobacco plant.

[0018] Preferably, the ultrasonic frequency used in the ultrasonic treatment in step 2) is 20-25 kHz. The use of this frequency for processing effectively further shortens the subsequent moisture recovery processing time and the amount of steam.

[0019] Preferably, when the processed tobacco sheets are upper or middle tobacco leaves, the ultrasonic frequency used in the ultrasonic treatment in step 2) is 20-25 kHz.

[0020] Preferably, when the processed tobacco sheets are upper tobacco leaves, the joint processing time in step 1) is 0.25-0.3 min.

[0021] Preferably, when the processed tobacco sheet is middle tobacco leaf, the common processing time in step 1) is 0.2-0.25 minutes.

[0022] The beneficial effects that can be produced by the present application include:

[0023] 1) The tobacco sheet redrying machine energy-saving redrying process for threshing and redrying provided by the present application can effectively improve the leaf structure porosity of the tobacco leaf entering the redrying section after continuous treatment by the method, so that water can more easily penetrate into the interior of the tobacco sheet, and the redrying efficiency of the multiple layers of tobacco sheets stacked in the equipment is improved, and the method is particularly suitable for efficient redrying of tobacco sheets with tightly organized surfaces after drying. The amount of steam used in the redrying treatment by the method can be reduced by about 0.3t compared with the existing method, and the water vapor pressure does not need to be increased. The method can be used in an environment with a relative humidity of less than 100% in the redrying section, which can avoid the phenomenon of water saturation in the air and reduce the phenomenon of uneven moisture of the tobacco sheet after redrying caused by water droplets falling on the tobacco sheet during the redrying process.

[0024] 2) The tobacco sheet redrying machine energy-saving redrying process for threshing and redrying provided by the present application can realize continuous production, effectively reduce energy consumption, and improve the redrying effect and quality by using the method for redrying.

[0025] 3) The tobacco sheet redrying machine energy-saving redrying process for threshing and redrying provided by the present application is suitable for the redrying of upper tobacco leaves and lower tobacco leaves, can effectively reduce the steam consumption during the redrying process of the tobacco sheet redrying machine, and can effectively meet the large-flow continuous production operation by redrying the tobacco sheet from a moisture content of 9.0% to about 12% in only about 1.2-1.6 minutes, thereby reducing the production operating cost. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The tobacco sheet redrying machine energy-saving redrying process flow provided in at least one embodiment of the present application is shown in the following schematic diagram: DETAILED DESCRIPTION

[0027] The present application will be further described in detail below in conjunction with the drawings and embodiments, but the present application is not limited in any way by the description, and any transformation or improvement based on the teaching of the present application falls within the protection scope of the present application.

[0028] EMBODIMENT

[0029] The materials and instruments used in the following embodiments are obtained from commercial channels unless otherwise specified; and the detection methods used are existing methods unless otherwise specified.

[0030] Embodiment 1: Redrying process for upper tobacco leaves

[0031] The upper tobacco leaves have the feature of relatively compact leaf surface structure organization, and accordingly, the moisture recovery treatment is performed according to the following steps:

[0032] 1. Ultrasonic wave + hot air fusion drying zone at the end of the baking process:

[0033] For the compact leaf surface structure of the upper tobacco leaves, the ultrasonic wave frequency is set at 45 kHz. The simultaneous action time of the hot air and the ultrasonic wave is adjusted to ensure that the tobacco sheet is dried to a moisture content of about 9.5% within 0.25-0.3 minutes.

[0034] 2. Cold cutting section treatment: The dried upper tobacco sheet enters the cold cutting section, and 25℃ cold cutting air is set to preliminarily cool. At the same time, the ultrasonic wave generating device is turned on, the frequency is set in the range of 20-25 kHz, and the treatment time is controlled at about 0.25 minutes to reduce the temperature of the tobacco sheet to about 28℃. This treatment process can avoid damaging the cell wall fiber structure of the broken tobacco leaves and further loosen the organization structure of the tobacco leaves.

[0035] 3. Moisture recovery section treatment: The upper tobacco sheet is sent to the moisture recovery section, and pure steam and water mixed atomization are used for moisture recovery. The treatment time is controlled at 1.5-1.8 minutes, the internal environment temperature of the moisture recovery section is maintained at 55-60℃, and the relative humidity is controlled in the range of 90%-95%.

[0036] 4. Final cold cutting section control: The moisture recovered upper tobacco sheet enters the final cold cutting section, the cold cutting air volume is adjusted according to the actual temperature of the tobacco sheet to ensure that the temperature of the tobacco sheet is reduced to the range of 45℃ before discharging.

[0037] Taking the upper tobacco leaves as an example, a large batch of tobacco sheets of 9800 kg / h are treated, and when the steam pressure is 0.8 Mpa, 1.8 t of steam is consumed per hour without ultrasonic wave shock treatment of the tobacco sheets; using the moisture recovery process shown in Example 1, about 1.2 t of steam is consumed per hour. The time of a single batch of tobacco leaves through the moisture recovery section is about 1.4 minutes.

[0038] After the method in Example 1 is used for treatment, the moisture of the superposed tobacco sheets in the middle part after moisture recovery is uniform with the moisture of the top and bottom tobacco leaves, which can effectively avoid the problem of insufficient local moisture recovery, and the moisture content of the top tobacco leaves is uniform without the occurrence of local water accumulation.

[0039] After using the original process for moisture recovery, the moisture content of the middle tobacco leaves is lower than that of the top and bottom tobacco sheets, and there is local water accumulation in the top tobacco sheets.

[0040] Example 2: Moisture recovery process for middle tobacco leaves

[0041] The middle tobacco leaves have relatively loose leaf surface structure organization, and accordingly, the moisture recovery treatment is performed according to the following steps:

[0042] 1. The ultrasonic + hot air drying zone at the end of the baking process: the ultrasonic frequency is set at 30 kHz, which can protect the structure of the tobacco leaves while facilitating the subsequent moisture recovery process. The action time of the hot air and the ultrasonic wave is adjusted to ensure that the tobacco sheet is dried to a moisture content of about 9% within 0.2-0.25 minutes. This treatment can effectively improve the diffusion rate and absorption efficiency of moisture in the tobacco leaves during the subsequent moisture recovery process.

[0043] 2. Cold cutting section processing: the dried middle tobacco sheet enters the cold cutting section, and 25℃ cold cutting air is set to cool down. The ultrasonic device is turned on, and the ultrasonic frequency is set to 20-25 kHz, and the processing time is controlled to about 0.2 minutes, so that the temperature of the tobacco sheet is reduced to about 26℃.

[0044] 3. Moisture recovery section processing: the middle tobacco sheet is sent to the moisture recovery section, and the moisture recovery is performed by using pure steam and water mixed atomization. After the treatment by using this process, the processing time of the middle tobacco leaves is effectively shortened to 1.2-1.5 minutes. At the same time, the internal environment temperature of the moisture recovery section is maintained at 50-55℃, and the relative humidity is controlled within the range of 85%-90%.

[0045] 4. Final cold cutting section control: the moisture recovered middle tobacco sheet enters the final cold cutting section. When the actual temperature of the outlet of the tobacco sheet is higher than 45℃, the cold cutting fan is turned on to ensure that the temperature of the tobacco sheet is reduced to the range of 45℃ before discharging.

[0046] In Example 2, when the process is used to process the middle tobacco leaves at a processing capacity of 9800 kg / h, and the steam pressure used is 0.8 Mpa, the original process consumes 1.5 t of steam per hour, and the moisture recovery processing time is 2.8-3.2 min. According to the method of Example 2, the moisture recovery process consumes 1.1 t of steam per hour, and the moisture recovery processing time is 1.2-1.6 min. The single batch of tobacco leaves passes through the moisture recovery section for about 1.2 min.

[0047] After the method in Example 2 is used, the moisture of the overlapped tobacco sheets of the middle part after moisture recovery is uniform with the moisture of the top and bottom tobacco leaves, which can effectively avoid the problem of insufficient moisture recovery in local areas, and the moisture content of the top tobacco leaves is uniform without local water accumulation.

[0048] After the original process is used for moisture recovery, the moisture content of the middle tobacco leaves is lower than that of the top and bottom tobacco sheets, and there is local water accumulation in the top tobacco sheets.

[0049] As can be seen from Examples 1-2, the method provided by the present application is suitable for moisture recovery processing of tobacco sheets of different parts, effectively improves the moisture recovery efficiency, shortens the moisture recovery time by about 1.2-1.6 min, reduces the moisture recovery temperature from about 75℃ to about 55℃, reduces the steam consumption during the moisture recovery stage, and stabilizes the moisture and temperature quality of the tobacco sheets after moisture recovery.

[0050] Although the present application has been described in detail with reference to the foregoing embodiments, the technical solutions recorded in the foregoing embodiments can be modified, or some of the technical features can be replaced by equivalent features, by those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A tobacco sheet redrying process for a tobacco sheet redrying machine for leaf tobacco, the tobacco sheet redrying machine being a mesh-belt box structure tobacco sheet redrying machine, the mesh-belt box structure tobacco sheet redrying machine comprising: The drying section, the cooling section and the moisture regaining section; characterized in that it comprises the following steps: 1) in the end area of the drying section and the cooling section, the superposed tobacco sheets are simultaneously subjected to hot air treatment and ultrasonic treatment, the hot air treatment and the ultrasonic treatment are jointly processed for 0.2-0.3 minutes, and the moisture content of the processed tobacco sheets is 9-10%; 2) in the cooling section, the superposed tobacco sheets are simultaneously subjected to air cooling treatment and ultrasonic treatment, the air cooling treatment and the ultrasonic treatment are jointly processed for 0.2-0.3 minutes, and the temperature of the processed tobacco sheets is controlled to be 25-30℃; 3) in the moisture regaining section, pure steam and water atomized mist are used, the temperature is controlled to be 50-60℃, the relative humidity is controlled to be 85-95%, and after processing for 1.2-1.8 minutes, the processed tobacco sheets enter the final cooling section for temperature reduction. In step 1), the ultrasonic frequency used for ultrasonic treatment is 30-50 kHz. In step 2), the ultrasonic frequency used for ultrasonic treatment is 20-25 kHz.

2. The energy saving conditioning process for leaf reconditioning machine of the tobacco leaf in the primary processing according to claim 1, characterized in that, When the processed tobacco sheets are upper tobacco leaves, the ultrasonic frequency used for ultrasonic treatment in step 1) is 45 kHz. When the processed tobacco leaves are middle tobacco leaves, the ultrasonic frequency used for ultrasonic treatment in step 1) is 30 kHz.

3. The energy saving conditioning process for leaf reconditioning machine of the tobacco sheet according to claim 1, characterized in that, When the processed tobacco sheets are upper or middle tobacco leaves, the ultrasonic frequency used for ultrasonic treatment in step 2) is 20-25 kHz.

4. The energy saving conditioning process for leaf reconditioning machine of the tobacco leaf in the primary cotton ginning process as claimed in claim 1, wherein, When the processed tobacco sheets are upper tobacco leaves, the joint processing time in step 1) is 0.25-0.3 minutes.

5. The energy saving conditioning process for leaf reconditioning machine for tobacco leaf in the primary cotton ginning process as claimed in claim 1 wherein, When the processed tobacco sheets are middle tobacco leaves, the joint processing time in step 1) is 0.2-0.25 minutes.

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