Optimized setting method for drying tunnel parameters after reconstituted tobacco coating

Abstract

The invention provides an optimal setting method for drying tunnel parameters after coating of reconstituted tobacco, which comprises the following steps: calculating the change condition of the coating rate of the reconstituted tobacco along with time according to the volume change condition of coating liquid drops, and further calculating the time when the reconstituted tobacco completely absorbs the coating liquid according to the coating rate of the product design requirement of the coating liquid. And the oven serial number corresponding to the product after the reconstituted tobacco is coated at the moment is calculated through the speed of the paper machine, and then the drying tunnel parameters after the reconstituted tobacco is coated are accurately optimized, so that the drying effect after the reconstituted tobacco is coated is improved, the sensory quality of the product is improved, and the adhesion and hardening conditions of the finished product are relieved.

Description

Technical Field

[0001] The invention belongs to the field of tobacco technology and relates to a method for optimizing the setting of drying tunnel parameters after coating of reconstituted tobacco leaves. Background Art

[0002] After coating, reconstituted tobacco production lines use hot air drying to dry the coated substrate to achieve the required moisture content and facilitate processing in the next step. During the actual drying process, the coated substrate enters the hot air drying system in an oven, where it is dried using a specific temperature and wind speed profile to dehydrate the substrate to the required dryness. To improve drying efficiency, both the hot air temperature and wind speed can be increased. Because aroma compounds in tobacco dissipate rapidly under high temperatures, affecting the sensory quality of the product, the drying temperature for reconstituted tobacco after coating is typically limited to a certain range. Furthermore, increasing the circulating hot air speed allows the air surrounding water molecules to be removed more quickly, increasing the chance of water molecules evaporating from the liquid surface and significantly improving the drying efficiency of the drying tunnel.

[0003] On the other hand, it takes time for the coating liquid to fully penetrate the substrate from the surface. As the speed of the reconstituted tobacco paper machine increases, the substrate surface often dehydrates too quickly, drying the coating liquid before it penetrates the substrate, forming a dry film of tobacco material. As drying continues, the surface becomes over-dried, potentially negatively impacting the sensory quality of the reconstituted tobacco product and causing the finished product to stick and harden after prolonged storage. Furthermore, internal moisture becomes difficult to remove, affecting drying efficiency.

[0004] The reconstituted tobacco industry often relies solely on field experience to adjust post-coating drying tunnel parameters, optimizing settings based on changes in product moisture content, physical properties, and sensory quality under different parameters. However, these optimizations are often reproducible and lack theoretical support. Therefore, setting appropriate hot air temperatures and fan frequencies in the reconstituted tobacco post-coating drying tunnel to prevent the coating liquid from drying out and forming a dry film before it fully penetrates the substrate is crucial for improving drying efficiency, enhancing product quality, and reducing sticking and hardening of the finished product. Summary of the Invention

[0005] To address the technical issues existing in the prior art, the present invention provides a method for optimizing the parameters of the drying tunnel after coating reconstituted tobacco leaves. This method ensures that the coating liquid does not form a dry film on the substrate surface before it is fully absorbed into the interior of the substrate, thereby preventing the subsequent evaporation of moisture from the substrate from being affected. This method improves the drying efficiency of the reconstituted tobacco leaves, avoids the impact of excessive surface drying on the sensory quality of the product, and reduces the occurrence of "white core" and sticking and hardening in the reconstituted tobacco leaves.

[0006] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for optimizing the parameters of a drying tunnel after coating of reconstituted tobacco leaves, the method comprising:

[0008] Dropping the coating liquid on the surface of the reconstituted tobacco leaf, and calculating the change in the coating rate of the coating liquid on the reconstituted tobacco leaf over time based on the change in the volume of the coating liquid droplet over time;

[0009] Determining the moment when the reconstituted tobacco leaves completely absorb the coating liquid based on the variation of the coating rate over time and the coating rate required by the product design of the coating liquid;

[0010] Calculate the oven number corresponding to the coated reconstituted tobacco product at that moment based on the paper machine speed;

[0011] Optimize the drying tunnel parameters, reduce the fan frequency of the ovens before this oven number, and increase the wind temperature and fan frequency of the ovens after this oven number.

[0012] As a preferred technical solution of the present invention, a contact angle meter is used to measure the change in the volume of the coating droplet over time.

[0013] As a preferred technical solution of the present invention, the contact angle meter is subjected to a heat preservation treatment for at least 10 minutes at a temperature that is the same as the coating liquid temperature according to on-site process parameters.

[0014] As a preferred technical solution of the present invention, a contact angle meter is used to measure the spherical cap height h and the bottom radius r' of the coating droplet, and the spherical cap radius r and the volume V of the coating droplet are calculated. Based on the volume V of the coating droplet at different moments, the volume ΔV of the coating liquid absorbed by the reconstituted tobacco leaf at the said moment is calculated. The calculation method is as follows: ΔV=V0-V t , where V0, V t represent the volumes of the coating liquid droplet at the initial moment and time t, respectively.

[0015] As a preferred technical solution of the present invention, the absolute dry weight of the coating liquid that has penetrated into the reconstituted tobacco leaf at time t is calculated based on the density M and concentration D of the coating liquid, and the bottom area of ​​the droplet at this time is S = πr' 2 , the coating rate per unit area at time t is obtained

[0016] As a preferred technical solution of the present invention, the absorption amount of the coating liquid completely absorbed by the reconstituted tobacco leaf is set to half of the absorption amount when the coating rate C' required by the product design of the coating liquid is achieved, then C t =C' / (2-C').

[0017] As a preferred technical solution of the present invention, the position vt reached by the substrate after coating at time t is obtained according to the speed v of the paper machine in the coating and drying section of the reconstituted tobacco leaves, and then the corresponding oven number is obtained according to the distance between each section of the oven and the coater in the paper machine process.

[0018] As a preferred technical solution of the present invention, the air temperature of the ovens before the oven sequence number is 60-100° C., and the fan frequency is 5-30% of the maximum fan frequency.

[0019] As a preferred technical solution of the present invention, the air temperature of the ovens after the oven serial number is 100-150° C., and the fan frequency is 30-90% of the maximum fan frequency.

[0020] As a preferred technical solution of the present invention, the method for optimizing the parameters of the drying tunnel after coating the reconstituted tobacco leaves includes:

[0021] The contact angle meter is subjected to a heat preservation treatment for at least 10 minutes at a temperature that is the same as the coating liquid temperature according to the on-site process parameters;

[0022] A coating droplet is placed on the surface of a reconstituted tobacco leaf, and a contact angle meter is used to measure the change in the volume of the coating droplet over time. Specifically, the contact angle meter is used to measure the spherical cap height h and the base radius r' of the coating droplet, and the spherical cap radius r and the volume V of the coating droplet are calculated. Based on the volume V of the coating droplet at different moments, the volume ΔV of the coating droplet absorbed by the reconstituted tobacco leaf at the said moment is calculated. The calculation method is as follows: ΔV=V0-V t , where V0, V t represent the volumes of the coating liquid droplet at the initial moment and at time t, respectively;

[0023] The absolute dry weight of the coating liquid that has penetrated into the reconstituted tobacco leaf at time t is calculated based on the density M and concentration D of the coating liquid. The bottom area of ​​the droplet at this time is S = πr' 2 , the coating rate per unit area at time t is obtained

[0024]

[0025] The moment when the reconstituted tobacco leaves completely absorb the coating liquid is determined according to the change of the coating rate over time and the coating rate required by the product design of the coating liquid. Specifically, the absorption amount of the reconstituted tobacco leaves when the coating liquid is completely absorbed is set to be half of the absorption amount when the coating rate C' required by the product design of the coating liquid is reached. Then C t =C' / (2-C');

[0026] According to the speed v of the paper machine in the coating and drying section of the reconstituted tobacco leaf, the position vt reached by the substrate after coating at time t is obtained, and then the corresponding oven number is obtained according to the distance between each drying section and the coating machine in the paper machine process;

[0027] The drying tunnel parameters are optimized. The air temperature of the ovens before the oven serial number is 60-100°C, and the fan frequency is 5-30% of the maximum fan frequency; the air temperature of the ovens after the oven serial number is 100-150°C, and the fan frequency is 30-90% of the maximum fan frequency.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] (1) The present invention provides a method for optimizing the parameters of the drying tunnel after coating of reconstituted tobacco leaves. The method ensures that the coating liquid does not form a dry film on the surface of the substrate before being fully absorbed into the interior of the substrate, thereby avoiding the influence of the evaporation of water inside the substrate at a later stage.

[0030] (2) The present invention provides a method for optimizing the parameters of the drying tunnel after coating of reconstituted tobacco leaves, which improves the drying efficiency of the reconstituted tobacco leaves and avoids the influence of excessive drying of the surface of the reconstituted tobacco leaves on the sensory quality of the product.

[0031] (3) The present invention provides a method for optimizing the parameters of the drying tunnel after coating of reconstituted tobacco leaves. This method can also reduce the occurrence of "white core" and adhesion and hardening of reconstituted tobacco leaf products because the coating liquid is fully absorbed into the interior of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the change in the coating droplet morphology in Example 1 of the present invention.

[0033] Figure 2 Schematic diagram of coating droplet morphology analysis in Example 1 of the present invention.

[0034] Figure 3 is the coating rate per unit area of ​​the reconstituted tobacco leaf in Example 1 of the present invention, C t Linear relationship fitting plot with time t.

[0035] The present invention is further described in detail below. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0036] The technical solution of this application is further explained below through specific implementation methods.

[0037] The present invention provides a method for optimizing the parameters of a drying tunnel after coating of reconstituted tobacco leaves, the method comprising:

[0038] Dropping the coating liquid on the surface of the reconstituted tobacco leaf, and calculating the change in the coating rate of the coating liquid on the reconstituted tobacco leaf over time based on the change in the volume of the coating liquid droplet over time;

[0039] Determining the moment when the reconstituted tobacco leaves completely absorb the coating liquid based on the variation of the coating rate over time and the coating rate required by the product design of the coating liquid;

[0040] Calculate the oven number corresponding to the coated reconstituted tobacco product at that moment based on the paper machine speed;

[0041] Optimize the drying tunnel parameters, reduce the fan frequency of the ovens before this oven number, and increase the wind temperature and fan frequency of the ovens after this oven number.

[0042] In the present invention, the change in the coating rate of the reconstituted tobacco leaves over time is calculated by the volume change of the coating droplets, and then the moment when the reconstituted tobacco leaves completely absorb the coating liquid is calculated according to the coating rate required by the product design of the coating liquid. The oven serial number corresponding to the reconstituted tobacco leaf coated product at that moment is calculated by the paper machine speed, and then the drying channel parameters of the reconstituted tobacco leaf after coating are accurately optimized, thereby improving the drying effect of the reconstituted tobacco leaf after coating, and at the same time, it is also beneficial to improve the sensory quality of the product and alleviate the adhesion and hardening of the finished product.

[0043] In one embodiment of the present invention, a contact angle meter is used to measure the change in the volume of the coating droplet over time.

[0044] In a specific embodiment of the present invention, the contact angle meter is subjected to a heat preservation treatment for at least 10 minutes at a temperature that is the same as the coating liquid temperature according to on-site process parameters.

[0045] In one specific embodiment of the present invention, reconstituted tobacco leaves are cut into a suitable size and placed at the center of the contact angle meter stage. The coating liquid and the dripping device (such as a syringe, a dropper, or the tip of a pipette, etc.) are thermostatted to the coating process temperature. The coating liquid droplets are then dropped onto the surface of the reconstituted tobacco leaf sample, and the morphological changes of the coating liquid droplets on the surface of the reconstituted tobacco leaf sample are recorded by a high-speed contact angle camera.

[0046] In a specific embodiment of the present invention, the blank reconstituted tobacco leaf substrate is taken from the production line before the coating machine, and the reconstituted tobacco leaf substrate needs to be sealed and stored before testing to ensure that its moisture content is consistent with that of the production line.

[0047] In one embodiment of the present invention, the size of the cut reconstituted tobacco leaf sample can be adjusted according to the size of the contact angle meter stage, so the size of the reconstituted tobacco leaf sample is not further limited. For example, the size of the reconstituted tobacco leaf sample can be a 50×50 mm square.

[0048] In one embodiment of the present invention, the contact angle meter's own software or image analysis software such as Photoshop is used to analyze the droplet morphology at the initial time t0 and time t when the droplet lands on the substrate.

[0049] In one embodiment of the present invention, a contact angle meter is used to measure the spherical cap height h and the base radius r' of the coating droplet, and the spherical cap radius r and the volume V of the coating droplet are calculated. Based on the volume V of the coating droplet at different moments, the volume ΔV of the coating liquid absorbed by the reconstituted tobacco leaf at the said moment is calculated. The calculation method is as follows: ΔV=V0-V t , where V0, V t represent the volumes of the coating liquid droplet at the initial moment and time t, respectively.

[0050] In one specific embodiment of the present invention, the spherical cap height h and bottom radius r' of the coating droplet obtained in the image analysis are not true values. The actual spherical cap height h and bottom radius r' of the coating droplet can be converted by comparing them with the liquid outlet diameter of a reference object, such as a dripping device (such as a syringe, a dropper, or a pipette tip).

[0051] In one embodiment of the present invention, the absolute dry weight of the coating liquid that has penetrated into the reconstituted tobacco leaf at time t is calculated based on the density M and concentration D of the coating liquid. The bottom area of ​​the droplet at this time is S = πr' 2 , the coating rate per unit area at time t is obtained

[0052] In one embodiment of the present invention, the absorption amount of the coating liquid completely absorbed by the reconstituted tobacco leaf is set to half of the absorption amount when the coating rate C' required by the product design of the coating liquid is achieved, then C t =C' / (2-C').

[0053] In one embodiment of the present invention, formula C t = C' / (2-C') is derived as follows: Assume that the coating liquid absorption per unit area of ​​the substrate is exactly half of the coating liquid absorption when the coating rate reaches the design value C'. When the coating rate per unit area is C t , the absolute dry weight of the substrate is g, then After sorting, we can get: C t =C' / (2-C').

[0054] In one embodiment of the present invention, the morphology of the coating droplets at multiple times t can be analyzed to obtain the spherical cap height h and the base radius r' at multiple times t, and then the coating rate per unit area of ​​the reconstituted tobacco leaf corresponding to the multiple times t can be obtained. t The coating rate per unit area of ​​reconstituted tobacco leaf C was obtained by curve fitting. t The relationship curve of Ct = C' / (2-C') to determine the time when the reconstituted tobacco leaves completely absorb the coating liquid.

[0055] In one specific embodiment of the present invention, the position vt reached by the substrate after coating at time t is obtained based on the speed v of the paper machine in the coated and dried section of the reconstituted tobacco leaves, and the corresponding oven number is then obtained based on the distance between each oven section and the coater in the paper machine process.

[0056] In a specific embodiment of the present invention, the air temperature of the ovens preceding the oven number is 60-100°C, and the fan frequency is 5-30% of the maximum fan frequency. The air temperature of the ovens preceding the oven number may be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C, and the fan frequency may be 5%, 10%, 15%, 20%, 25%, or 30% of the maximum fan frequency, but are not limited to the values ​​listed above. Other values ​​within the above ranges that are not listed are also applicable.

[0057] In a specific embodiment of the present invention, the air temperature of the ovens after the oven serial number is 100-150°C, and the fan frequency is 30-90% of the maximum fan frequency. The air temperature of the ovens before the oven serial number may be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, or 150°C, and the fan frequency may be 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the maximum fan frequency, but are not limited to the listed values. Other values ​​not listed within the above numerical ranges are also applicable.

[0058] In one embodiment of the present invention, the method for optimizing the parameters of the drying tunnel after coating the reconstituted tobacco leaves comprises:

[0059] The contact angle meter is subjected to a heat preservation treatment for at least 10 minutes at a temperature that is the same as the coating liquid temperature according to the on-site process parameters;

[0060] A coating droplet is placed on the surface of a reconstituted tobacco leaf, and a contact angle meter is used to measure the change in the volume of the coating droplet over time. Specifically, the contact angle meter is used to measure the spherical cap height h and the base radius r' of the coating droplet, and the spherical cap radius r and the volume V of the coating droplet are calculated. Based on the volume V of the coating droplet at different moments, the volume ΔV of the coating droplet absorbed by the reconstituted tobacco leaf at the said moment is calculated. The calculation method is as follows: ΔV=V0-V t , where V0, V t represent the volumes of the coating liquid droplet at the initial moment and at time t, respectively;

[0061] The absolute dry weight of the coating liquid that has penetrated into the reconstituted tobacco leaf at time t is calculated based on the density M and concentration D of the coating liquid. The bottom area of ​​the droplet at this time is S = πr' 2 , the coating rate per unit area at time t is obtained

[0062]

[0063] The moment when the reconstituted tobacco leaves completely absorb the coating liquid is determined according to the change of the coating rate over time and the coating rate required by the product design of the coating liquid. Specifically, the absorption amount of the reconstituted tobacco leaves when the coating liquid is completely absorbed is set to be half of the absorption amount when the coating rate C' required by the product design of the coating liquid is reached. Then C t =C' / (2-C');

[0064] According to the speed v of the paper machine in the coating and drying section of the reconstituted tobacco leaf, the position vt reached by the substrate after coating at time t is obtained, and then the corresponding oven number is obtained according to the distance between each drying section and the coating machine in the paper machine process;

[0065] The drying tunnel parameters are optimized. The air temperature of the ovens before the oven serial number is 60-100°C, and the fan frequency is 5-30% of the maximum fan frequency; the air temperature of the ovens after the oven serial number is 100-150°C, and the fan frequency is 30-90% of the maximum fan frequency.

[0066] To better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0067] Example 1

[0068] This embodiment provides a method for optimizing the parameters of a drying tunnel after coating of reconstituted tobacco leaves, the method comprising:

[0069] The drying tunnel parameters after coating of a certain brand of reconstituted tobacco leaves were optimized. The coating rate of this product is 39% (C'), the coating liquid density is 1.20g / ml (M), the solid content is 38% (D), and the paper machine speed is 140m / s. Take the intact and flat substrate produced by the paper machine of the production line, cut it into 50×50mm square size and stick it to the center of the contact angle measuring instrument test bench with double-sided tape. The moisture content is 26%, which is maintained before on-site coating. Take the coating liquid and keep it warm in a 50℃ water bath. The insulation temperature is consistent with the on-site coating liquid temperature. The contact angle measuring instrument syringe is kept warm in the same 50℃ water bath for more than 10 minutes. After taking it out and wiping the surface dry, quickly absorb the coating liquid and drop a drop of coating liquid on the substrate surface. The morphological changes of the coating liquid droplet on the substrate surface are recorded by a high-speed camera, such as Figure 1 shown.

[0070] The contact angle measuring instrument's built-in software is used to analyze the initial moment t when the droplet lands on the substrate. o And the droplet shape at time t, according to Figure 2 The ratio of the height h and bottom radius r' of the spherical droplet on the substrate surface to the needle diameter a (known to be 0.487 mm) can be used to calculate the actual size of h and r, the radius r of the spherical cap, and the volume V of the droplet. The amount of coating liquid that penetrates into the substrate, ΔV, can then be calculated based on the change in the droplet volume at different time points. The calculation method is as follows: ΔV=V0-V t , where V0, V t Represent the volume of the coating liquid droplet at the initial time and time t respectively. According to the bottom area of ​​the droplet at this time S=πr' 2 The substrate coating rate per unit area is obtained The settlement results are shown in Table 1.

[0071] Table 1

[0072] t / s h / mm r' / mm r / mm <![CDATA[V / mm 3 ]]> <![CDATA[ΔV / mm 3 ]]> <![CDATA[S / mm 2 ]]> C / ％ 0 1.674 1.275 1.385 7.281 0.000 5.105 0 1.52 1.516 1.418 1.507 7.228 0.052 6.317 3.776 3.03 1.309 1.604 1.764 7.147 0.134 8.085 7.549 4.52 1.157 1.747 2.069 7.073 0.207 9.593 9.861 6.02 1.065 1.833 2.314 6.983 0.298 10.560 12.854 7.55 1.004 1.891 2.511 6.898 0.383 11.230 15.548 9.02 0.944 1.948 2.742 6.789 0.492 11.921 18.803 10.55 0.883 2.005 3.013 6.654 0.626 12.633 22.611 12.04 0.852 2.034 3.166 6.576 0.705 12.996 24.721 13.54 0.822 2.063 3.333 6.490 0.790 13.365 26.965 15.04 0.791 2.091 3.515 6.397 0.884 13.739 29.343

[0073] According to the calculation results in Table 1, the coating rate per unit area of ​​reconstituted tobacco leaf C is obtained by fitting. t The relationship curve with time t, such as Figure 3 As shown. It can be seen that there is a good linear relationship between the droplet substrate contact time and the substrate coating rate per unit area C t =0.0195t+0.0096.

[0074] When the coating liquid absorption per unit area of ​​the substrate is half of the coating liquid absorption amount, the coating rate is It can be calculated that t' = 11.92s at this time. The test process was repeated, with the substrate facing the mesh side and the back mesh side each three times, and the average t' was 11.77s. The test results are shown in Table 2.

[0075] Table 2

[0076] Parallel experiments 1 2 3 average RSD / % Mesh surface 11.92 12.81 13.17 12.63 5.09 Back mesh 11.32 10.68 10.71 10.90 3.31 11.77 8.98

[0077] As shown in Table 3, the time it takes for the paper web to reach the corresponding drying oven from the coating machine can be calculated based on the vehicle speed and the belt length between each drying oven and the coating machine. Therefore, according to this calculation, the amount of coating liquid absorbed by one side of the substrate by the time the paper web enters the fifth drying oven is half of the amount required for a 39% coating rate. In other words, the amount of coating liquid equivalent to a 39% coating rate for double-sided dip coating can be absorbed into the substrate.

[0078] Table 3

[0079]

[0080] According to the absorption of the coating liquid in the substrate, the hot air temperature and fan frequency before the fifth oven section are set to lower values, the hot air temperature is 60-90°C, and the fan frequency is 20-25% of the maximum fan frequency. The fan frequency is increased after the fifth oven section, the hot air temperature is 100-130°C, and the frequency is 40-60% of the maximum fan frequency. The optimization scheme is shown in Table 4.

[0081] Table 4

[0082]

[0083] In order to ensure that the outlet moisture content is qualified (13-15%), the oven equipment parameters are adjusted during production. The results are shown in Table 5.

[0084] Table 5

[0085]

[0086] After adjustment, the moisture content at the oven outlet is 13.8%, which meets the process requirements.

[0087] The samples obtained after the oven equipment parameters were optimized were subjected to moisture balance under constant temperature and humidity conditions (22±2°C, 60±5%), and their physical properties were tested and compared with those of the samples before optimization. The results are shown in Figure 6.

[0088] Among them, the test methods for bulk, surface adhesion and softness are as follows:

[0089] After the samples were equilibrated with moisture according to the requirements of GB / T 16447-2004, the basis weight, thickness, surface adhesion, and softness were measured according to the standard methods of GB / T 451.2-2002, GB / T 451.3-2002, ISO 4624:2024, and GB / T 8942-2016. The bulk was calculated as B=T / g, where B is the bulk of the sample (cm 3 / g); T is the thickness of a single sample (cm); g is the sample weight (g / m 2 ).

[0090] Table 6

[0091] sample <![CDATA[Bulk thickness / cm 3 / g]]> Surface adhesion / mN Softness / mN Before optimizing oven equipment parameters 2.28 133.1 1107.2 After optimizing oven equipment parameters 2.07 74.2 809.6

[0092] Test results show that after optimizing the oven parameters, the bulk of the finished product decreased, indicating that the tobacco substances in the coating liquid have effectively penetrated the substrate, greatly reducing the formation of a dry film layer on the tobacco leaf surface. Consequently, the surface adhesion and softness of the finished product also decreased significantly (the lower the softness test value, the better the sample's softness).

[0093] The comparative evaluation results of product sensory quality before and after optimization of oven equipment parameters are shown in Table 7.

[0094] Table 7

[0095] sample Sensory quality evaluation results Before optimizing oven equipment parameters The burning sensation is more obvious, the aftertaste is slightly weak, and the smoke is dull After optimizing oven equipment parameters Low stimulation, light burning sensation, comfortable aftertaste, full and wide smoke

[0096] The results of sensory quality evaluation show that after the optimization of the oven equipment parameters, the irritation and burning sensation of the product are reduced, the aftertaste is comfortable, and the smoke performance is also improved.

[0097] Example 2

[0098] This embodiment provides a method for optimizing the parameters of a drying tunnel after coating of reconstituted tobacco leaves, the method comprising:

[0099] The drying tunnel parameters after coating of a certain brand of reconstituted tobacco leaves were optimized. The coating rate of this product is 40% (C'), the density of the coating liquid is 1.21g / ml (M), the solid content is 39% (D), and the paper machine speed is 130m / s. Take the intact and flat substrate produced by the paper machine of the production line, cut it into 50×50mm square size and stick it to the center of the contact angle measuring instrument test bench with double-sided tape. The moisture content is 24%, which is maintained before on-site coating. Take the coating liquid and keep it warm in a 50℃ water bath. The insulation temperature is consistent with the on-site coating liquid temperature. The contact angle measuring instrument syringe is kept warm in the same 50℃ water bath for more than 10 minutes. After taking it out and wiping the surface dry, quickly absorb the coating liquid and drop a drop of coating liquid on the substrate surface. The morphological changes of the coating liquid droplet on the substrate surface are recorded by a high-speed camera, such as Figure 1 shown.

[0100] The contact angle measuring instrument's built-in software is used to analyze the initial moment t when the droplet lands on the substrate. o And the droplet shape at time t, according to Figure 2 The ratio of the height h and bottom radius r' of the spherical cap of the medium spherical droplet on the substrate surface to the diameter a of the needle (known to be 0.487 mm) can be used to calculate the actual size of h and r, as well as the cap radius r and the volume V of the droplet. Then, the amount of coating liquid ΔV that penetrates into the substrate can be calculated based on the change in the droplet volume at different time points.

[0101] According to the coating rate per unit area of ​​reconstituted tobacco leaves C t The linear relationship with time t, C t =0.0299t+0.0043. When the coating liquid absorption per unit area of ​​the substrate is just half of the coating liquid absorption amount when the coating rate reaches the design value C' (40%), the coating rate is It can be calculated that t' = 8.21s at this time. The test process was repeated, with the substrate facing the mesh side and the back mesh side each three times, and the average t' was 8.05s. The test results are shown in Table 8.

[0102] Table 8

[0103] Parallel experiments 1 2 3 average RSD / % Mesh surface 8.21 9.47 8.53 8.74 7.50 Back mesh 7.32 6.74 8.03 7.36 8.77 8.05 11.81

[0104] As shown in Table 9, the time it takes for the paper web to reach the corresponding drying oven from the coating machine can be calculated based on the vehicle speed and the belt length between each drying oven and the coating machine. Therefore, according to this calculation, the amount of coating liquid absorbed by one side of the substrate by the time the paper web enters the third drying oven is half of the amount required for a 40% coating rate. In other words, the amount of coating liquid equivalent to a 40% coating rate for double-sided dip coating can be absorbed into the substrate.

[0105] Table 9

[0106]

[0107] According to the absorption of the coating liquid in the substrate, the hot air temperature and fan frequency before the fifth oven section are set to lower values, the hot air temperature is 60-80°C, and the fan frequency is 20-30% of the maximum fan frequency. The fan frequency is increased after the fifth oven section, the hot air temperature is 100-120°C, and the frequency is 40-60% of the maximum fan frequency. The optimization scheme is shown in Table 10.

[0108] Table 10

[0109]

[0110] In order to ensure that the outlet moisture content is qualified (13-15%), the oven equipment parameters are adjusted during production. The results are shown in Table 11.

[0111] Table 11

[0112]

[0113] After adjustment, the moisture content at the oven outlet is 13.3%, which meets the process requirements.

[0114] The samples obtained after the oven equipment parameters were optimized were subjected to moisture balance under constant temperature and humidity conditions (22±2°C, 60±5%), and their physical properties were tested and compared with those of the samples before optimization. The results are shown in Table 12.

[0115] Table 12

[0116] sample <![CDATA[Bulk density / cm 3 / g]]> Surface adhesion / mN Softness / mN Before optimizing oven equipment parameters 2.39 157.5 926.1 After optimizing oven equipment parameters 2.11 89.4 769.3

[0117] Test results show that after optimizing the oven parameters, the bulk of the finished product decreased, indicating that the tobacco substances in the coating liquid have effectively penetrated the substrate, greatly reducing the formation of a dry film layer on the tobacco leaf surface. Consequently, the surface adhesion and softness of the finished product also decreased significantly (the lower the softness test value, the better the sample's softness).

[0118] The comparative evaluation results of product sensory quality before and after optimization of oven equipment parameters are shown in Table 13.

[0119] Table 13

[0120] sample Sensory quality evaluation results Before optimizing oven equipment parameters The irritation and burning are more obvious, and the mixed gas is slightly After optimizing oven equipment parameters Little stimulation, light burning sensation, good fragrance

[0121] The sensory quality evaluation results show that after the oven equipment parameters are optimized, the irritation and burning sensation of the product are reduced, the aftertaste is comfortable, and the aroma quality is also improved.

[0122] The applicant declares that the present invention is intended to illustrate the detailed structural features of the present invention through the above-described embodiments, but the present invention is not limited to the above-described detailed structural features. This does not mean that the present invention must rely on the above-described detailed structural features in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for selected components, additions of auxiliary components, and selection of specific embodiments, etc., fall within the scope of protection and disclosure of the present invention.

[0123] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0124] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0125] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for optimizing the parameters of a drying tunnel after coating of reconstituted tobacco leaves, characterized in that: The method comprises: Dropping the coating liquid on the surface of the reconstituted tobacco leaf, and calculating the change in the coating rate of the coating liquid on the reconstituted tobacco leaf over time based on the change in the volume of the coating liquid droplet over time; Determining the moment when the reconstituted tobacco leaves completely absorb the coating liquid according to the variation of the coating rate over time and the coating rate required by the product design of the coating liquid; Calculate the oven number corresponding to the coated reconstituted tobacco product at the time according to the paper machine speed; Optimize the drying tunnel parameters, reduce the fan frequency of the ovens before the sequence number, and increase the wind temperature and fan frequency of the ovens after the sequence number.

2. The optimization setting method according to claim 1, characterized in that: The change in the volume of the coating droplet over time was measured using a contact angle meter.

3. The optimization setting method according to claim 2, characterized in that: The contact angle meter is subjected to a heat preservation treatment for at least 10 minutes at a temperature which is the same as the temperature of the coating liquid according to the on-site process parameters.

4. The optimization setting method according to claim 3, characterized in that: The spherical cap height h and the base radius r' of the coating droplet were measured using a contact angle meter, and the spherical cap radius r and the volume V of the coating droplet were calculated. Based on the volume V of the coating droplet at different moments, the volume ΔV of the coating liquid absorbed by the reconstituted tobacco leaf at the moment was calculated. The calculation method is as follows: ΔV=V0-V t , where V0, V t represent the volumes of the coating liquid droplet at the initial moment and time t, respectively.

5. The optimization setting method according to claim 4, characterized in that: The absolute dry weight of the coating liquid that has penetrated into the reconstituted tobacco leaf at time t is calculated based on the density M and concentration D of the coating liquid. The bottom area of ​​the droplet at this time is S = πr' 2 , the coating rate per unit area at time t is obtained 6. The optimization setting method according to claim 1, characterized in that: Assume that the absorption amount of the coating liquid completely absorbed by the reconstituted tobacco leaf is half of the absorption amount when the coating rate C' required by the product design of the coating liquid is achieved, then C t =C' / (2-C').

7. The optimization setting method according to claim 1, characterized in that: According to the speed v of the paper machine in the coated and dried section of the reconstituted tobacco leaf, the position vt reached by the substrate after coating at time t is obtained, and then the corresponding oven number is obtained according to the distance between each section of the drying oven and the coating machine in the paper machine process.

8. The optimization setting method according to claim 1, characterized in that: The air temperature of the ovens before the oven serial number is 60-100° C., and the fan frequency is 5-30% of the maximum fan frequency.

9. The optimization setting method according to claim 1, characterized in that: The air temperature of the ovens after the oven serial number is 100-150° C., and the fan frequency is 30-90% of the maximum fan frequency.

10. The optimization setting method according to any one of claims 1 to 9, characterized in that: The method comprises: The contact angle meter is subjected to a heat preservation treatment for at least 10 minutes at a temperature that is the same as the coating liquid temperature according to the on-site process parameters; A coating droplet is placed on the surface of a reconstituted tobacco leaf, and a contact angle meter is used to measure the change in the volume of the coating droplet over time. Specifically, the contact angle meter is used to measure the spherical cap height h and the base radius r' of the coating droplet, and the spherical cap radius r and the volume V of the coating droplet are calculated. Based on the volume V of the coating droplet at different moments, the volume ΔV of the coating droplet absorbed by the reconstituted tobacco leaf at the said moment is calculated. The calculation method is as follows: ΔV=V0-V t , where V0, V t represent the volumes of the coating liquid droplet at the initial moment and at time t, respectively; The absolute dry weight of the coating liquid that has penetrated into the reconstituted tobacco leaf at time t is calculated based on the density M and concentration D of the coating liquid. The bottom area of ​​the droplet at this time is S = πr' 2 , the coating rate per unit area at time t is obtained The moment when the reconstituted tobacco leaves completely absorb the coating liquid is determined according to the change of the coating rate over time and the coating rate required by the product design of the coating liquid. Specifically, the absorption amount of the reconstituted tobacco leaves when the coating liquid is completely absorbed is set to be half of the absorption amount when the coating rate C' required by the product design of the coating liquid is reached. Then C t =C' / (2-C'); According to the speed v of the paper machine in the coating and drying section of the reconstituted tobacco leaf, the position vt reached by the substrate after coating at time t is obtained, and then the corresponding oven number is obtained according to the distance between each drying section and the coating machine in the paper machine process; The drying tunnel parameters are optimized. The air temperature of the ovens before the oven serial number is 60-100°C, and the fan frequency is 5-30% of the maximum fan frequency; the air temperature of the ovens after the oven serial number is 100-150°C, and the fan frequency is 30-90% of the maximum fan frequency.

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