A method for predicting moisture content of cut tobacco based on rapid moisture absorption characteristic curve

Abstract

A method for predicting the moisture content of cut tobacco based on a rapid moisture absorption characteristic curve comprises the following steps: Step 1: studying the moisture adsorption / desorption characteristics of cut tobacco to obtain the equilibrium dry basis moisture content M of sample S1 under the required environmental conditions; e and effective water diffusion coefficient D eff Step 2: Initial dry basis moisture content M of the tobacco sample S2 to be tested during processing ds Equation derivation; Step 3: Prediction of the initial dry basis moisture content of the tobacco sample corresponding to the process during processing. The present invention uses the thermal moisture analyzer to obtain the equilibrium dry basis moisture content of the tobacco corresponding to the environmental conditions, obtains the moisture diffusion coefficient of the tobacco under the above environmental conditions according to Fick's second law, and obtains the initial dry basis moisture content of the tobacco sample to be tested through model derivation.

Description

Technical Field

[0001] The invention relates to the technical field of tobacco processing, in particular to a method for predicting the moisture content of shredded tobacco based on a rapid moisture absorption characteristic curve. Background Art

[0002] During the tobacco processing, it will undergo multiple wet heat treatment steps, such as traditional cigarette tobacco drying, rehumidification, leaf moisturizing, re-roasting, drying, recycled tobacco leaf film making, drying and other series of wet heat treatment steps. The change of tobacco moisture content in each process is nonlinear and time-varying. Therefore, timely acquisition of tobacco moisture content information is the basis for achieving precise control of production conditions during tobacco processing.

[0003] At present, the tobacco industry usually installs infrared moisture measurement devices on tobacco conveyor belts. This method has a simple test process and can realize continuous online monitoring, but the test sensitivity is low and there are certain measurement errors. Laboratories often use the oven method to determine the moisture content of tobacco samples, setting the temperature to 105℃±2℃ until the sample reaches constant weight at this temperature. The oven method test process is relatively complicated and time-consuming, and is not suitable for continuous monitoring; at the same time, due to the high drying temperature, some volatile components escape, affecting the measurement accuracy. In the process of tobacco product processing, timely and accurate prediction of the moisture content of tobacco is of practical significance for production process control. Summary of the invention

[0004] In order to overcome the existing defects, the present invention proposes a method for predicting the moisture content of shredded tobacco based on a rapid moisture absorption characteristic curve.

[0005] A method for predicting the moisture content of cut tobacco based on a rapid moisture absorption characteristic curve, comprising:

[0006] Step 1: Study the moisture adsorption / desorption characteristics of cut tobacco to obtain the equilibrium dry basis moisture content M of sample S1 under the required environmental conditions e and effective water diffusion coefficient D eff ;

[0007] Step 2: Initial dry basis moisture content M of the tobacco sample S2 to be tested during processing ds Derivation of equations;

[0008] Step 3: Prediction of initial dry basis moisture content of tobacco samples corresponding to the processing step.

[0009] Among them, the step 1: studying the moisture adsorption / desorption characteristics of cut tobacco, obtaining the equilibrium dry basis moisture content M of sample S1 under the required environmental conditions e and effective water diffusion coefficient D eff ,

[0010] Determine the wet basis moisture content M of sample S1 using the specified method w , initial dry basis moisture content Md , unit is % d .

[0011]

[0012]

[0013] Where m w is the absolute water content of S1 sample, in g; m s is the mass of the S1 sample, in g. The mass change curve of the tobacco shreds to achieve moisture adsorption or desorption equilibrium under the required environmental conditions is obtained by means of a thermal moisture analyzer. The equilibrium dry basis moisture content M of the tobacco shreds is obtained based on the mass change curve. e .

[0014]

[0015] Where m e is the mass of the sample reaching adsorption or desorption equilibrium, in g; m0 is the initial mass of the sample, in g.

[0016] From the above, we can get the dry basis moisture content M of sample S1 at time t: t And relative dry basis moisture content MR.

[0017]

[0018]

[0019] Where m t is the mass of the sample at time t, in g.

[0020] According to the simplified Fick's second law, D eff , the calculation formula is as follows:

[0021]

[0022] Where L is half of the thickness of the tobacco, in meters; t is the corresponding time, in seconds; the slope obtained by linear fitting of ln(MR)~t can be used to obtain D under this condition. eff , unit is m 2 / s; A is introduced to facilitate formula derivation.

[0023] Wherein, the step 2: the initial dry basis moisture content M of the tobacco sample S2 to be tested during processing ds Derivation of equations;

[0024] Assuming that the obtained D eff Under the set environmental conditions, it is a constant value. ds The calculation formula is as follows:

[0025]

[0026] Among them, the prediction of the initial dry basis moisture content of the tobacco sample corresponding to the process during the processing,

[0027] Take a certain mass of tobacco sample from the processing site and place it in a heat and humidity analyzer with set temperature and relative humidity to obtain the adsorption / desorption mass change curve of tobacco sample under the environmental conditions within t time. Ignore the influencing factors under this condition on D eff The role of M e , D eff If A does not change, then A is only related to time. The initial dry basis moisture content M of the tobacco sample can be predicted by formula (7): ds .

[0028] The steps 1 and 2 only require a single experiment to be conducted when the test conditions are formulated to obtain the parameter values ​​required under the conditions, and on this basis, the moisture content of the series of tobacco samples to be tested is predicted.

[0029] The present invention adopts a thermo-humidity analyzer capable of adjusting ambient temperature and relative humidity to obtain a tobacco cut adsorption / desorption mass change curve within a set time under corresponding ambient conditions, and predicts the initial dry basis moisture content of the tobacco cut based on the obtained curve.

[0030] The thermal moisture analyzer includes but is not limited to a tobacco thermal moisture online analyzer and a multi-sample tobacco / material moisture adsorption and desorption instrument.

[0031] The tobacco heat and moisture online analyzer is a patent product of the inventor, ZL 200510107366.X, ZL200720090560.6, and ZL 201020539746.7.

[0032] The multi-sample tobacco / material moisture adsorption and desorption instrument is a patented product of the inventor, ZL201210267723.9, ZL 201510307227.5, ZL 201911284693.0, and ZL 201911283062.7.

[0033] The set time can be limited to within 15 minutes.

[0034] The present invention adopts the thermal moisture analyzer to obtain the equilibrium dry basis moisture content of tobacco under corresponding environmental conditions, obtains the moisture diffusion coefficient of tobacco under the above environmental conditions according to Fick's second law, and obtains the initial dry basis moisture content of the tobacco sample to be tested through model deduction.

[0035] The present invention provides a method for predicting the moisture content of cut tobacco based on a rapid moisture absorption characteristic curve. With the help of a heat and moisture analyzer capable of adjusting environmental conditions, the quality change curve of cut tobacco under set environmental conditions is quickly obtained, and the initial dry basis moisture content of the cut tobacco product is predicted accordingly. The method can achieve the initial dry basis moisture content of the cut tobacco sample in the online production process by simply measuring the equilibrium dry basis moisture content of the cut tobacco under the environmental conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the dynamic moisture adsorption curve of tobacco at 40℃ and 80%RH.

[0037] Figure 2 This is the dry basis moisture content curve of tobacco at 40℃ and 80%RH.

[0038] Figure 3 It is the ln(MR)~t curve of relative dry basis moisture content of tobacco.

[0039] Figure 4 It is the dynamic moisture adsorption curve of the tested tobacco at 40℃ and 80%RH for 10 minutes. DETAILED DESCRIPTION

[0040] The following is a detailed description of a method for predicting the moisture content of shredded tobacco based on a rapid moisture absorption characteristic curve provided by the present invention in conjunction with the accompanying drawings and specific embodiments.

[0041] A method for predicting the moisture content of cut tobacco based on a rapid moisture absorption characteristic curve, comprising:

[0042] Step 1: Study the moisture adsorption / desorption characteristics of cut tobacco to obtain the equilibrium dry basis moisture content M of sample S1 under the required environmental conditions e and effective water diffusion coefficient D eff ;

[0043] Step 2: Initial dry basis moisture content M of the tobacco sample S2 to be tested during processing ds Derivation of equations;

[0044] Step 3: Prediction of initial dry basis moisture content of tobacco samples corresponding to the processing step.

[0045] Among them, the step 1: studying the moisture adsorption / desorption characteristics of cut tobacco, obtaining the equilibrium dry basis moisture content M of sample S1 under the required environmental conditions e and effective water diffusion coefficient D eff ,

[0046] Determine the wet basis moisture content M of sample S1 using the specified method w , initial dry basis moisture content M d , unit is % d .

[0047]

[0048]

[0049] Where m w is the absolute water content of S1 sample, in g; m s is the mass of S1 sample, in g,

[0050] The heat and moisture analyzer is used to obtain the mass change curve of the tobacco to achieve moisture adsorption or desorption equilibrium under the required environmental conditions, and the equilibrium dry basis moisture content M of the tobacco is obtained based on the mass change curve. e .

[0051]

[0052] Where m e is the mass of the sample reaching adsorption or desorption equilibrium, in g; m0 is the initial mass of the sample, in g.

[0053] From the above, we can get the dry basis moisture content M of sample S1 at time t: t And relative dry basis moisture content MR.

[0054]

[0055]

[0056] Where m t is the mass of the sample at time t, in g.

[0057] According to the simplified Fick's second law, D eff , the calculation formula is as follows:

[0058]

[0059] Where L is half of the thickness of the tobacco, in meters; t is the corresponding time, in seconds; the slope obtained by linear fitting of ln(MR)~t can be used to obtain D under this condition. eff , unit is m 2 / s; A is introduced to facilitate formula derivation.

[0060] Wherein, the step 2: the initial dry basis moisture content M of the tobacco sample S2 to be tested during processing ds Derivation of equations;

[0061] Assuming that the obtained D eff Under the set environmental conditions, it is a constant value. ds The calculation formula is as follows:

[0062]

[0063] Among them, the prediction of the initial dry basis moisture content of the tobacco sample corresponding to the process during the processing,

[0064] Take a certain mass of tobacco sample from the processing site and place it in a heat and humidity analyzer with set temperature and relative humidity to obtain the adsorption / desorption mass change curve of tobacco sample under the environmental conditions within t time. Ignore the influencing factors under this condition on D eff The role of M e , D eff If A does not change, then A is only related to time. The initial dry basis moisture content M of the tobacco sample can be predicted by formula (7): ds .

[0065] The steps 1 and 2 only require a single experiment to be conducted when the test conditions are formulated to obtain the parameter values ​​required under the conditions, and on this basis, the moisture content of the series of tobacco samples to be tested is predicted.

[0066] Example

[0067] The present invention is described in conjunction with the embodiments.

[0068] Step 1: The tobacco sample S1 is balanced at a dry basis moisture content M at 40°C and 80% RH. e and effective water diffusion coefficient D eff ,

[0069] (1) Take (2.0050±0.0500)g of cut tobacco sample S1 from the redrying process and place it in 10mL of extractant. After shaking for (30±15)min, take the upper clear liquid as the test sample and determine its moisture content m by gas chromatography. w The wet basis moisture content is 0.1069 g. w , initial dry basis moisture content M d They are 10.64% and 11.91% respectively.

[0070] (2) Figure 1 As shown, the dynamic moisture adsorption curve m of the sample under 40°C and 80% RH conditions was obtained using a multi-sample tobacco / material moisture adsorption and desorption instrument. t ~t. Figure 2 As shown, the moisture content curve M of the cut tobacco on a dry basis under this condition is obtained. t ~t, 315min later, the sample reaches moisture absorption equilibrium, and the equilibrium dry basis moisture content M e is 21.47%. Figure 3 As shown, tobacco M t After processing, the ~t curve can obtain the tobacco relative dry basis moisture content ln(MR)~t curve.

[0071] Depend on Figure 3 The linear fitting slope of -0.0002 can be used to obtain the D of the tobacco under this condition.eff is 6.37×10 -11 m 2 / s.

[0072] Step 2: Based on the value obtained in step 1, get the initial dry basis moisture content M of the sample ds The expression is as follows:

[0073]

[0074] Wherein, A is expressed as formula (9).

[0075] A=-2.0×10 -4 ×t-0.1228 (9)

[0076] Step 3: If Figure 4 As shown, 2.0 g of tobacco cut from this process was randomly selected and the dynamic moisture adsorption curve m was obtained under the conditions of 40°C and 80% RH for 10 min (600 s) using a multi-sample tobacco / material moisture adsorption and desorption instrument. t ~t, 10min sample weight m t The initial dry basis moisture content of the batch of materials is 10.02% as obtained by formula (8).

[0077] Finally, it should be noted that the above embodiments are only used to describe the technical solution of the present invention rather than to limit the technical method. The present invention can be extended to other modifications, changes, applications and embodiments in application, and therefore it is believed that all such modifications, changes, applications and embodiments are within the spirit and teaching scope of the present invention.

Claims

1. A method for predicting the moisture content of cut tobacco based on a rapid moisture absorption characteristic curve, comprising: Step 1: Study the moisture adsorption / desorption characteristics of cut tobacco to obtain the equilibrium dry basis moisture content M of sample S1 under the required environmental conditions e and effective water diffusion coefficient D eff ; Step 2: Initial dry basis moisture content M of the tobacco sample S2 to be tested during processing ds Derivation of equations; Step 3: Prediction of initial dry basis moisture content of tobacco samples in the corresponding process during processing. Among them, the step 1: studying the moisture adsorption / desorption characteristics of cut tobacco, obtaining the equilibrium dry basis moisture content M of sample S1 under the required environmental conditions e and effective water diffusion coefficient D eff , Determine the wet basis moisture content M of sample S1 using the specified method w , initial dry basis moisture content M d , in % d , Where m w is the absolute water content of S1 sample, in g; m s is the mass of S1 sample, in g, The heat and moisture analyzer is used to obtain the mass change curve of the tobacco to achieve moisture adsorption or desorption equilibrium under the required environmental conditions, and the equilibrium dry basis moisture content M of the tobacco is obtained based on the mass change curve. e , Where m e The mass of the sample corresponding to the adsorption or desorption equilibrium, in g; m0 is the initial mass of the sample, in g, From the above, we can get the dry basis moisture content M of sample S1 at time t: t and relative dry basis moisture content MR, Where m t is the mass of the sample at time t, in g, According to the simplified Fick's second law, D eff , the calculation formula is as follows: Where L is half of the thickness of the tobacco, in meters; t is the corresponding time, in seconds; the slope obtained by linear fitting of ln(MR)~t can be used to obtain D under this condition. eff , Unit: m 2 / s; It is convenient to introduce A into the formula derivation; Wherein, the step 2: the initial dry basis moisture content M of the tobacco sample S2 to be tested during processing ds Derivation of equations; Assuming that the obtained D eff Under the required environmental conditions, it is a constant value. ds The calculation formula is as follows: Step 3: Prediction of initial dry basis moisture content of tobacco samples corresponding to the processing step during processing, Take a certain mass of tobacco sample from the processing site and place it in a heat and humidity analyzer with set temperature and relative humidity to obtain the adsorption / desorption mass change curve of tobacco sample under the environmental conditions within t time. Ignore the influencing factors under this condition on D eff The role of M e , D eff If A does not change, then A is only related to time. The initial dry basis moisture content M of the tobacco sample can be predicted by formula (7): ds .

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