Method for inhibiting browning of flue-cured tobacco lamina and vacuum moisture regaining system

Abstract

The invention belongs to the technical field of tobacco processing equipment, and particularly relates to a method for inhibiting browning of tobacco strips and a vacuum moisture regaining system. The method for inhibiting browning of the flue-cured tobacco lamina comprises the following steps that a dynamic weighing subsystem is started during feeding, when the accumulated weight reaches a set value, an interlocking signal is triggered to stop feeding, and meanwhile an intelligent control unit calls technological parameters of corresponding tobacco leaf varieties; the intelligent control unit starts the vacuumizing subsystem to vacuumize the vacuum moisture regaining box body, when the vacuum degree reaches a set value, a steam valve is opened, and when the temperature reaches 60 DEG C, the collaborative injection subsystem is started to inject feed liquid; and negative pressure cooling is adopted in the pressure relief stage, and the cooled flue-cured tobacco strips are discharged. According to the technical scheme, after the tobacco strips enter the vacuum moisture regaining process, dynamic weighing can be achieved, then the moisture regaining steam injection amount and the feed liquid application amount are controlled, the tobacco leaf quality is improved, and browning of the tobacco strips is restrained.

Description

Technical Field

[0001] This invention belongs to the technical field of tobacco processing equipment, specifically relating to a method for inhibiting browning of tobacco leaves and a vacuum rehumidification system. Background Technology

[0002] As the raw material for cigarettes, tobacco leaves need to undergo processes such as rehydration and additives after entering the cigarette factory from the time they are threshed and re-dried. Vacuum rehydration is a key process for adjusting the moisture content of tobacco leaves and improving their physical properties, while the additive process is an important means of improving the quality and sensory quality of tobacco leaves.

[0003] However, existing technologies have the following drawbacks: First, they lack a mechanism to inhibit browning in tobacco leaves. Traditional equipment relies on pure steam treatment, which cannot simultaneously apply antioxidants during the rehumidification stage. This leads to uncontrolled polyphenol oxidase (PPO) activity, resulting in uneven dark spots on the tobacco leaf surface and a decrease in the L* value (brightness) of the tobacco leaves by 8-12%. Second, the application precision of functional liquid is insufficient. Existing vacuum rehumidification uses a post-feeding system, spraying the liquid after rehumidification. However, because the surface of the tobacco leaves has already formed a dense structure, the liquid penetration rate is less than 40%, and the spraying ratio error is as high as ±0.25%. Over-spraying... Spraying causes tobacco leaves to stick together (caking rate ≥3%), and insufficient spraying of liquid cannot effectively inhibit browning, with the BI value of tobacco leaves only decreasing by 5-8%; thirdly, the weighing and feeding systems are disconnected. Traditional vacuum rehumidification feeding weighing uses static scales with a measurement error ≥1.5% and cannot provide real-time data feedback. For example, when processing 1200kg of tobacco leaves, the actual amount of feed can deviate by ±18kg, resulting in waste of liquid or insufficient efficiency. At the same time, the interval between weighing and feeding actions exceeds 5 minutes, and steam prehumidification has changed the liquid absorption characteristics of tobacco leaves (porosity decreases by 22%), affecting the uniformity of liquid absorption.

[0004] Currently, the industry has not yet organically combined vacuum rehumidification and feeding processes to improve the quality and processing characteristics of tobacco flakes. Therefore, how to achieve accurate weighing of tobacco flakes during vacuum rehumidification while simultaneously inhibiting browning and integrating rehumidification and feeding has become a key issue in improving tobacco flake quality. Current technologies have not adequately addressed this problem, necessitating a new vacuum rehumidification system and method to meet the high standards required for industrial production. Summary of the Invention

[0005] The purpose of this invention is to provide a method and vacuum rehumidification system for inhibiting browning of tobacco leaves based on dynamic weighing and precise feeding. When the tobacco leaves enter the vacuum rehumidification process, dynamic weighing can be achieved, thereby controlling the amount of rehumidification steam injected and the amount of liquid applied, to improve tobacco quality and inhibit browning.

[0006] To achieve the above objectives, this application employs the following technical solution:

[0007] A method for inhibiting browning in tobacco leaves includes the following steps:

[0008] Step 1, Pre-treatment of smoke blocks:

[0009] When feeding, the dynamic weighing subsystem is activated. When the cumulative weight reaches the set value, an interlock signal is triggered to stop feeding. At the same time, the intelligent control unit calls the process parameters of the corresponding tobacco variety.

[0010] Step 2, Coordinated Spraying Phase:

[0011] The intelligent control unit starts the vacuum subsystem to evacuate the vacuum rehumidification chamber. When the vacuum level reaches -0.085MPa, the steam valve is opened and the heating rate is 4℃ / min. When the temperature reaches 60℃, the collaborative injection subsystem is started to inject liquid.

[0012] Step 3, Post-processing optimization:

[0013] Negative pressure cooling is used during the depressurization stage, and the tobacco flakes are discharged after cooling.

[0014] Furthermore, in step 2, the liquid is applied in two stages:

[0015] First stage: When the tobacco leaf temperature is between 60℃ and 68℃, the liquid injection volume accounts for 70%, and the particle size is ≤20μm, to quickly form an antioxidant film;

[0016] Second stage: When the temperature of tobacco leaves is between 68℃ and 72℃, the amount of liquid sprayed accounts for 30%, and the particle size is ≤50μm to enhance deep penetration.

[0017] Furthermore, in step 2, the formula for calculating the feed rate of the collaborative injection subsystem for liquid injection is as follows:

[0018] Q = K·M·(1+α·ΔH),

[0019] In the formula, Q is the amount of material added, K is the preset ratio of tobacco leaves to liquid material, K=0.2~0.3%, M is the weight of tobacco leaves before rehydration, which is measured in real time by the dynamic weighing subsystem (13), α is the moisture content deviation correction term, α=0.15, ΔH is the moisture content deviation term, ΔH=(H actual − H reference) / H reference, where H actual represents the actual moisture content, and H reference represents the preset moisture content.

[0020] Furthermore, the liquid composition consists of 8-10 g / L of tea polyphenols, 3.5-4.2 g / L of quercetin, 2.0-2.5 g / L of solanesol, and 0.5-0.8 g / L of sodium citrate by mass fraction.

[0021] Furthermore, in step 3, the specific steps are as follows: the vacuum subsystem is activated to ensure that the inside of the vacuum rehumidification chamber is under negative pressure of -0.02MPa, so that the temperature of the tobacco leaves drops from 72℃ to below 45℃ within 8 minutes, reducing thermal degradation, and the cooled tobacco leaves are discharged.

[0022] A vacuum rehumidification system for inhibiting browning of tobacco leaves, used in any of the methods for inhibiting browning of tobacco leaves as described above, includes a vacuum rehumidification unit, a liquid storage unit, and an intelligent control unit. The vacuum rehumidification unit includes a vacuum rehumidification chamber, a vacuuming subsystem, a dynamic weighing subsystem, and a coordinated spraying subsystem. The discharge end of the material conveying system is connected to the vacuum rehumidification chamber, the inlet of the vacuuming subsystem is connected to the vacuum rehumidification chamber, the dynamic weighing subsystem is located below the discharge end of the material conveying system inside the vacuum rehumidification chamber, the spray port of the coordinated spraying subsystem is connected to the vacuum rehumidification chamber, and the inlet of the coordinated spraying subsystem is connected to the liquid storage unit. The dynamic weighing subsystem, the material conveying system, the vacuuming subsystem, and the coordinated spraying subsystem are all electrically connected to the intelligent control unit.

[0023] Furthermore, the dynamic weighing subsystem employs a double-beam load cell, which is installed at the bottom of the vacuum rehumidification chamber. The lower end of the double-beam load cell is rigidly connected to the bottom of the vacuum rehumidification chamber. The nonlinear error of the double-beam load cell is ≤0.03%, the temperature drift is ±0.002% / ℃, and it sends weight data to the control unit every 0.5 seconds to calibrate the cumulative error in real time.

[0024] Furthermore, the collaborative injection subsystem includes an air compressor pump station, a liquid storage tank, a liquid delivery pipeline, a steam storage unit, a steam storage tank, a steam delivery pipeline, a liquid mixing chamber, and a steam-liquid composite nozzle. The air compressor pump station is connected to the liquid storage unit and the steam storage unit respectively, delivering the liquid from the liquid storage unit to the storage tank and the steam from the steam storage unit to the steam storage tank. The steam and liquid are then mixed in the liquid mixing chamber through the liquid delivery pipeline and the steam delivery pipeline. The liquid mixing chamber is fixed inside the vacuum rehumidification chamber at the top. The steam-liquid composite nozzle is arranged below the liquid mixing chamber, with an adjustable injection angle of ±45°, and the injection is performed 20cm from the surface of the tobacco.

[0025] Furthermore, the liquid storage unit is equipped with a spiral tube heat exchanger to maintain the liquid temperature at 25±0.5℃, and a magnetic stirrer at a speed of 80-120 rpm is used to prevent sedimentation.

[0026] Furthermore, the intelligent control unit measures the moisture content of the tobacco leaves after rehydration using a near-infrared sensor, and then controls the feeding amount through a flow valve. The intelligent control unit includes a human-machine interface, a touch screen that displays real-time curves, and supports one-click import of process parameters.

[0027] The beneficial effects of this invention are:

[0028] This technical solution provides a vacuum rehumidification system and method for inhibiting the browning of tobacco leaves based on dynamic weighing and precise feeding. When the tobacco leaves enter the vacuum rehumidification process, dynamic weighing can be achieved, thereby controlling the amount of rehumidification steam injection and the amount of liquid applied, so as to improve the quality of tobacco leaves and inhibit the browning of tobacco leaves. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the vacuum rehumidification system of the present invention.

[0030] Figure 2 This is a front view of the vacuum rehumidification system of the present invention.

[0031] Figure 3 This is a side view of the vacuum rehumidification system of the present invention.

[0032] Figure 4 This is a bar chart showing the browning value (BI) variation according to an embodiment of the present invention.

[0033] Figure 5 This is a line graph showing the change in L* value according to an embodiment of the present invention.

[0034] Figure 6 This is a line graph showing the spraying ratio and standard deviation of the liquid material in an embodiment of the present invention.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. Vacuum rehumidification unit; 2. Liquid storage unit; 3. Intelligent control unit; 11. Vacuum rehumidification chamber; 12. Vacuum pumping subsystem; 13. Dynamic weighing subsystem; 14. Cooperative jetting subsystem; 131. Double beam load cell; 141. Air compression pump station; 142. Liquid storage tank; 143. Liquid conveying pipeline; 144. Steam storage unit; 145. Steam storage tank; 146. Steam conveying pipeline; 147. Liquid mixing chamber; 148. Steam-liquid composite nozzle. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, but the present invention is not limited thereto. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0038] The following example uses the vacuum rehumidification process of Xiaomutou brand tobacco produced by Henan China Tobacco Industry Co., Ltd. as an example. Five batches were processed according to different batches, and the specific steps included as follows:

[0039] This application provides a method for inhibiting browning of tobacco leaves, comprising the following steps:

[0040] Step 1, Pre-treatment of smoke blocks:

[0041] The dynamic weighing subsystem is activated during feeding. When the cumulative weight reaches a set value (e.g., 300kg ± 50kg), an interlock signal is triggered to stop feeding. The intelligent control unit calls the corresponding process parameters for the tobacco variety (e.g., K=0.25% for flue-cured tobacco K326 and K=0.28% for burley tobacco TN90). The process parameters for the corresponding tobacco varieties in this application are data obtained through separate tests previously.

[0042] Step 2, Coordinated Spraying Phase:

[0043] The intelligent control unit activates the vacuum subsystem to evacuate the vacuum rehumidification chamber. When the vacuum level reaches -0.085MPa, the steam valve is opened (heating rate 4℃ / min). When the temperature reaches 60℃, the coordinated injection subsystem is activated to inject liquid.

[0044] In this application, the liquid is applied in two stages:

[0045] First stage (60-68℃): 70% of the liquid is sprayed, with a particle size ≤20μm, to quickly form an antioxidant film;

[0046] Second stage (68-72℃): The liquid injection volume accounts for 30%, and the particle size is ≤50μm to enhance deep penetration.

[0047] Step 3, Post-processing optimization:

[0048] During the depressurization stage, negative pressure cooling is adopted. The vacuum subsystem is activated to ensure that the inside of the vacuum rehumidification chamber is under negative pressure (-0.02MPa), so that the temperature of the tobacco leaves drops from 72℃ to below 45℃ within 8 minutes, reducing thermal degradation (quercetin retention rate ≥95%). After cooling, the tobacco leaves are discharged. The liquid conveying pipeline is closed by the intelligent control unit, and the steam conveying pipeline works alone to complete the cleaning of the steam-liquid composite nozzle, preventing liquid residue from clogging (cleaning water pressure 0.8MPa, time 2 minutes).

[0049] In this application, the formula for calculating the feed amount of the collaborative injection subsystem for liquid injection in step 2 is as follows:

[0050] Q = K·M·(1+α·ΔH),

[0051] In the formula, Q is the amount of material added, K is the preset ratio of tobacco flakes to liquid material, K=0.2~0.3%, M is the weight of tobacco flakes before rehydration, which is measured in real time by the dynamic weighing subsystem, α is the moisture content deviation correction term, α=0.15, ΔH is the moisture content deviation term, ΔH=(Hactual − HBase) / HBase, where Hactual represents the actual moisture content and HBase represents the preset moisture content.

[0052] In this application, the feed solution is composed of the following components by mass fraction: 8-10 g / L of tea polyphenols, used to inhibit PPO activity; 3.5-4.2 g / L of quercetin, used to increase the L* value; 2.0-2.5 g / L of solanesol, used to promote the release of aroma-producing substances; and 0.5-0.8 g / L of sodium citrate, used for pH buffering (maintaining 5.6-5.8).

[0053] In this application, the intelligent control unit measures the moisture content of the tobacco leaves after rehydration using a near-infrared sensor, and then controls the feeding amount through a flow valve. The intelligent control unit includes a human-machine interface, a touch screen that displays real-time curves (weight, flow rate, temperature), and supports one-click import of parameters (adapting to preset schemes for different tobacco leaf varieties).

[0054] This application provides a vacuum rehumidification system for inhibiting browning of tobacco flakes, such as... Figures 1 to 3 As shown, the method for inhibiting browning of tobacco flakes for any of the above-mentioned purposes includes a vacuum rehumidification unit 1, a material storage unit 2, and an intelligent control unit 3. The vacuum rehumidification unit includes a vacuum rehumidification chamber, a vacuuming subsystem, a dynamic weighing subsystem, and a coordinated spraying subsystem. The discharge end of the material conveying system is connected to the vacuum rehumidification chamber, the inlet of the vacuuming subsystem is connected to the vacuum rehumidification chamber, the dynamic weighing subsystem is located below the discharge end of the material conveying system inside the vacuum rehumidification chamber, the spray port of the coordinated spraying subsystem is connected to the vacuum rehumidification chamber, and the inlet of the coordinated spraying subsystem is connected to the material storage unit. The dynamic weighing subsystem, the material conveying system, the vacuuming subsystem, and the coordinated spraying subsystem are all electrically connected to the intelligent control unit.

[0055] The material conveying system transports the tobacco flakes into the vacuum rehumidification chamber. The dynamic weighing subsystem measures the weight of the tobacco flakes in real time. The vacuuming subsystem 12 evacuates the inside of the vacuum rehumidification chamber 11. The coordinating injection subsystem 14 mixes the liquid and steam in a certain proportion. Based on the feedback from the dynamic weighing subsystem, the steam-liquid mixture is quantitatively sprayed onto the vacuumed tobacco flakes to complete the rehumidification and feeding of the tobacco flakes.

[0056] In this application, the dynamic weighing subsystem 13 employs a double-beam load cell 131, which is installed at the bottom of the vacuum rehumidification chamber and rigidly connected directly to the chamber to eliminate dynamic interference. The double-beam load cell 131 has a weighing range of 200-2000 kg, a nonlinearity error ≤0.03%, a temperature drift of ±0.002% / ℃, and sends weight data to the control unit every 0.5 seconds for real-time calibration of accumulated errors.

[0057] In this application, the collaborative injection subsystem consists of an air compressor pump station 141, a liquid storage tank 142, a liquid delivery pipeline 143, a steam storage unit 144, a steam storage tank 145, a steam delivery pipeline 146, a liquid mixing chamber 147, and a steam-liquid composite nozzle 148. The air compressor pump station 141 is connected to the liquid storage unit 2 and the steam storage unit 144 respectively, delivering the liquid in the liquid storage unit 2 to the storage tank 142, and delivering the steam in the steam storage unit 144 to the steam storage tank 145. The steam and liquid are then mixed in the liquid mixing chamber 147 through the liquid delivery pipeline 143 and the steam delivery pipeline 146. The liquid mixing chamber 147 is fixed inside the vacuum rehumidification chamber 11 at the top. The steam-liquid composite nozzle 145 is arranged below the liquid mixing chamber 147, with an adjustable injection angle of ±45°, and is injected at a distance of 20cm from the surface of the tobacco.

[0058] In this application, the liquid storage unit 2 is equipped with a spiral tube heat exchanger to maintain the liquid temperature at 25±0.5℃, and a magnetic stirrer (rotation speed 80-120rpm) is used to prevent sedimentation.

[0059] like Figures 4 to 6 As shown, the effect of the example is:

[0060] 1. Browning inhibition rate: After using the vacuum rehumidification system for synergistic inhibition of browning of tobacco proposed in this invention, after five consecutive batches of production, the BI value decreased from 50-60 in the traditional process to 20-25 after the invention (a decrease of ≥55%), and the L* value remained stable at 50-53 (the tobacco industry standard YB / T 234-2018 requires ≥45).

[0061] Process stability: Five consecutive batches of production tests showed that the standard deviation of the liquid spraying ratio was only 0.1%, which is significantly better than the industry standard (≤0.5%).

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for inhibiting browning in tobacco leaves, characterized in that, Includes the following steps: Step 1, Pre-treatment of smoke blocks: When feeding, the dynamic weighing subsystem is activated. When the cumulative weight reaches the set value, an interlock signal is triggered to stop feeding. At the same time, the intelligent control unit calls the process parameters of the corresponding tobacco variety. Step 2, Coordinated Spraying Phase: The intelligent control unit starts the vacuum subsystem to evacuate the vacuum rehumidification chamber. When the vacuum level reaches -0.085MPa, the steam valve is opened and the heating rate is 4℃ / min. When the temperature reaches 60℃, the collaborative injection subsystem is started to inject liquid. Step 3, Post-processing optimization: Negative pressure cooling is used during the depressurization stage, and the tobacco flakes are discharged after cooling.

2. The method for inhibiting browning of tobacco leaves according to claim 1, characterized in that, In step 2, the liquid is applied in two stages: First stage: When the tobacco leaf temperature is between 60℃ and 68℃, the liquid injection volume accounts for 70%, and the particle size is ≤20μm, to quickly form an antioxidant film; Second stage: When the temperature of tobacco leaves is between 68℃ and 72℃, the amount of liquid sprayed accounts for 30%, and the particle size is ≤50μm to enhance deep penetration.

3. The method for inhibiting browning of tobacco leaves according to claim 1, characterized in that, In step 2, the formula for calculating the feed rate of the collaborative injection subsystem for liquid injection is as follows: Q = K·M·(1+α·ΔH), In the formula, Q is the amount of material added, K is the preset ratio of tobacco leaves to liquid material, K=0.2~0.3%, M is the weight of tobacco leaves before rehydration, which is measured in real time by the dynamic weighing subsystem (13), α is the moisture content deviation correction term, α=0.15, ΔH is the moisture content deviation term, ΔH=(H actual − H reference) / H reference, where H actual represents the actual moisture content, and H reference represents the preset moisture content.

4. The method for inhibiting browning of tobacco leaves according to claim 1, characterized in that, The liquid composition consists of 8-10 g / L of tea polyphenols, 3.5-4.2 g / L of quercetin, 2.0-2.5 g / L of solanesol, and 0.5-0.8 g / L of sodium citrate by mass fraction.

5. The method for inhibiting browning of tobacco leaves according to claim 1, characterized in that, Step 3 specifically involves: starting the vacuum subsystem to ensure a negative pressure of -0.02MPa inside the vacuum rehumidification chamber, causing the tobacco leaf temperature to drop from 72℃ to below 45℃ within 8 minutes, reducing thermal degradation, and then discharging the cooled tobacco leaves.

6. A vacuum rehumidification system for inhibiting browning of tobacco leaves, used in the method for inhibiting browning of tobacco leaves according to any one of claims 1 to 5, characterized in that, The system includes a vacuum rehumidification unit, a liquid storage unit, and an intelligent control unit. The vacuum rehumidification unit comprises a vacuum rehumidification chamber, a vacuuming subsystem, a dynamic weighing subsystem, and a coordinated spraying subsystem. The discharge end of the material conveying system is connected to the vacuum rehumidification chamber, the inlet of the vacuuming subsystem is connected to the vacuum rehumidification chamber, the dynamic weighing subsystem is located below the discharge end of the material conveying system inside the vacuum rehumidification chamber, the spray port of the coordinated spraying subsystem is connected to the vacuum rehumidification chamber, and the inlet of the coordinated spraying subsystem is connected to the liquid storage unit. The dynamic weighing subsystem, the material conveying system, the vacuuming subsystem, and the coordinated spraying subsystem are all electrically connected to the intelligent control unit.

7. The vacuum rehumidification system for inhibiting browning of tobacco leaves according to claim 6, characterized in that, The dynamic weighing subsystem uses a double-beam load cell, which is installed at the bottom of the vacuum rehumidification chamber. The lower end of the double-beam load cell is rigidly connected to the bottom of the vacuum rehumidification chamber. The nonlinear error of the double-beam load cell is ≤0.03%, the temperature drift is ±0.002% / ℃, and it sends weight data to the control unit every 0.5 seconds to calibrate the cumulative error in real time.

8. The vacuum rehumidification system for inhibiting browning of tobacco leaves according to claim 6, characterized in that, The coordinated injection subsystem includes an air compressor pump station, a liquid storage tank, a liquid delivery pipeline, a steam storage unit, a steam storage tank, a steam delivery pipeline, a liquid mixing chamber, and a steam-liquid composite nozzle. The air compressor pump station is connected to the liquid storage unit and the steam storage unit respectively, delivering the liquid from the liquid storage unit to the storage tank and the steam from the steam storage unit to the steam storage tank. The steam and liquid are then delivered to the liquid mixing chamber through the liquid delivery pipeline and the steam delivery pipeline to achieve mixing of steam and liquid. The liquid mixing chamber is fixed inside the vacuum rehumidification chamber at the top. The steam-liquid composite nozzle is arranged below the liquid mixing chamber, with an adjustable injection angle of ±45°, and the injection is performed at a distance of 20cm from the surface of the tobacco.

9. The vacuum rehumidification system for inhibiting browning of tobacco leaves according to claim 6, characterized in that, The liquid storage unit is equipped with a spiral tube heat exchanger to maintain the liquid temperature at 25±0.5℃, and a magnetic stirrer at a speed of 80-120 rpm is used to prevent sedimentation.

10. The vacuum rehumidification system for inhibiting browning of tobacco leaves according to claim 6, characterized in that, The intelligent control unit measures the moisture content of the tobacco leaves after rehydration using a near-infrared sensor, and then controls the feeding amount through a flow valve. The intelligent control unit includes a human-machine interface, a touch screen that displays real-time curves, and supports one-click import of process parameters.

Images