Continuous online grouped stem washing method

Abstract

The invention relates to the technical field of tobacco processing, and discloses a continuous online grouped stem washing method, which comprises the following steps: grouping various grades of tobacco stems according to the moisture content of the soaked various grades of tobacco stems, and correspondingly calculating the soaking time required for soaking different groups until the moisture content is the same, so as to match the scraper motor frequencies corresponding to the different groups; the tobacco stems are fed according to the sequence from large water absorption rate to small water absorption rate, the frequency of the scraper motor is automatically adjusted according to the cumulant of the electronic belt scale, online continuous grouping processing is achieved, the water content of the tobacco stems of all grades after the tobacco stems of the same batch are washed can be relatively consistent, and then the stem cutting quality is improved. The processing strength of the cut tobacco drying procedure and the moisture stability of cut stems are improved, the effects of online grouping and continuous production of a complete tobacco stem formula are achieved on the premise that production batches are not increased, the batch changing waiting time is shortened, the production efficiency is not reduced, and the moisture stability of the tobacco stems and the follow-up processing quality are improved.

Description

Technical Field

[0001] The invention relates to the technical field of tobacco processing, in particular to a continuous on-line grouping stem washing method. Background Art

[0002] Tobacco stems are an important raw material component of cigarette production. Affected by varieties, parts, etc., the organizational structures of tobacco stems of different grades vary greatly, resulting in large differences in their water absorption performance. As an important process for tobacco stem pretreatment, the stem washing process has the task of increasing the moisture content and temperature of tobacco stems and improving the processing resistance of tobacco stems. The production process mainly uses the scraper conveying system of the stem washing machine to force the tobacco stems to be immersed in warm water for a set time and output continuously and evenly. The length of the stem immersion time is determined by the scraper motor frequency. The tobacco stem formula of each production batch contains multiple grades. The water absorption rate of different grades of stem washing varies greatly, while the tobacco stem soaking time is the same, resulting in significant differences in the moisture content of different grades of tobacco stems after water absorption, affecting the quality of shredded and the stability of subsequent processing. Some brands use group processing to reduce the large difference in moisture after stem washing caused by grade differences, but the method of dividing a complete batch into several small batches for group processing increases the number of batches and the number of equipment starts and stops, affecting production efficiency and equipment energy consumption.

[0003] A Chinese invention patent with publication number CN111109632A discloses a quality control method and system based on water-immersion tobacco stem conditioning. The method establishes a moisture content PID feedback control model and performs feedback control on the outlet moisture content by adjusting the immersion time, so that the outlet moisture content of the tobacco stem conditioning process within the batch is controlled according to the target value.

[0004] A Chinese invention patent with publication number CN112826119B discloses a moisture balance control method and system for water-immersed tobacco stem rehumidification. The method establishes a corresponding relationship between the outlet moisture content of the tobacco stems and the immersion temperature and immersion time. According to the target value of the outlet moisture content of the tobacco stems, the preset immersion temperature and the preset immersion time are determined. Then, a moisture content PID feedback control model is established. The moisture stability of the tobacco stems is controlled by adjusting the steam valve opening to stabilize the immersion temperature.

[0005] The inventors found that the above two methods are essentially to detect the moisture content of the tobacco stems after washing online, and then feedback to control the soaking time and soaking temperature. However, the correspondence between the moisture content of the tobacco stems and the soaking time and soaking temperature does not take into account the problem of the water absorption rate of tobacco stems of different grades, and the online infrared moisture meter only detects the moisture content on the surface of the tobacco stems, and the error of the feedback signal is relatively large. Summary of the invention

[0006] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a continuous online grouping method for washing tobacco stems. By grouping tobacco stems of each grade according to the moisture content after soaking, and correspondingly calculating the soaking time required for different groups to reach the same moisture content, the scraper motor frequency corresponding to different groups is matched, and the feeding is carried out in the order of the tobacco stem water absorption rate from large to small. The scraper motor frequency is automatically adjusted according to the cumulative amount of the electronic belt scale, so that the moisture content of tobacco stems of each grade after washing is relatively consistent, thereby improving the quality of cut tobacco shreds. It can realize online grouping and continuous production of a complete tobacco stem formula, and reduce the waiting time for batch change.

[0007] To achieve the above object, the present invention is realized by the following technical solutions:

[0008] A continuous online grouping method for washing tobacco stems, comprising the following steps:

[0009] Step 1: Group tobacco stems of each grade according to the moisture content after soaking.

[0010] Step 2: Establish a regression equation between the moisture content and soaking time of each group of tobacco stems to obtain the soaking time required for each group of tobacco stems to reach the same moisture content.

[0011] Step 3: Establish a regression equation between the scraper motor frequency of the tobacco stem washer and the obtained soaking time to obtain the scraper motor frequency required for each group of tobacco stems.

[0012] Step 4: Link the cumulative amount of tobacco stems before washing with the obtained scraper motor frequency. Each group of tobacco stems is fed in the order of the tobacco stem water absorption rate from large to small, and the scraper motor frequency is automatically adjusted according to the cumulative amount of the electronic belt scale.

[0013] As a further implementation method, in Step 1, take the same mass of tobacco stems of each grade, soak them in hot water under set conditions, then take out the tobacco stems, process the tobacco stems and detect the moisture content of the tobacco stems to obtain the moisture content of the corresponding grade of tobacco stems.

[0014] As a further implementation method, use the analysis of variance method to conduct a significance analysis of the differences in the moisture content of the detected tobacco stems of each grade, and then divide the grades with no significant difference in the moisture content of the tobacco stems into one group.

[0015] As a further implementation method, in Step 2, take the same mass of each group of tobacco stems, and ensure that the mass of tobacco stems of each grade in each group is the same. Soak them under set conditions, take out each group of tobacco stems at different soaking times in turn and detect the moisture content. According to the moisture content of each group of tobacco stems at different soaking times, calculate the corresponding relationship between the moisture content of the tobacco stems and the soaking time, establish a regression equation, and according to the required moisture content of the tobacco stems and the established regression equation, obtain the soaking time required for each group of tobacco stems to reach the same moisture content.

[0016] As a further implementation method, in step 3, multiple frequencies of the scraper motor are set respectively. At each frequency, a set mass of tobacco stems is added at the inlet of the tobacco stem washer, and timing is started. At the outlet of the tobacco stem washer, the times when the first and the last tobacco stems appear are recorded respectively, and the average value of the two groups of times is used as the soaking time for a single test.

[0017] As a further implementation method, according to the set frequency of the scraper motor and the soaking time of the tobacco stems at the corresponding frequency tested, the corresponding relationship between the frequency and the time is calculated, and a regression equation is established; the soaking times required for each group of tobacco stems determined in step 2 are substituted into the regression equation to obtain the frequencies of the scraper motor required for each group of tobacco stems.

[0018] As a further implementation method, in step 4, an automatic control program for the frequency of the scraper motor of the tobacco stem washer is added to the control system of the tobacco stem washer. Then, each group of tobacco stems is distributed according to the decreasing order of the water absorption rate. Taking the cumulative weight of the electronic belt scale before washing the tobacco stems as a signal, the frequency of the scraper motor is automatically adjusted according to the change of the distribution of the tobacco stem groups.

[0019] As a further implementation method, the weights of each group of tobacco stems are input into the control system according to the water absorption rate respectively. Then, the tobacco stem washer is started, and the tobacco stems are distributed according to the arranged order of the tobacco stem groups.

[0020] As a further implementation method, when the tobacco stem formula is adjusted, the distribution order needs to be rearranged.

[0021] As a further implementation method, after rearranging the distribution order, the weights of each group of tobacco stems need to be input again.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. By grouping each grade of tobacco stems according to the moisture content after soaking of each grade of tobacco stems, calculating the soaking time required for different groups to reach the same moisture content correspondingly, matching the corresponding frequencies of the scraper motor for different groups, and feeding the materials in the order of decreasing water absorption rate of the tobacco stems, and automatically adjusting the frequency of the scraper motor according to the cumulative amount of the electronic belt scale, the present invention realizes online continuous grouping processing. The present invention can make the moisture content of each grade of tobacco stems relatively consistent after washing the tobacco stems of the same batch, thereby improving the quality of cut tobacco shreds, enhancing the processing intensity of the tobacco drying process and the stability of the moisture content of the cut tobacco stems, achieving the effect of online grouping and continuous production of a complete tobacco stem formula without increasing the production batches, reducing the waiting time for batch change, not reducing the production efficiency, and improving the moisture stability of the tobacco stems and the subsequent processing quality.

[0024] 2. When the tobacco stem formula is adjusted in the present invention, according to this method, tobacco stems of different grades can be regrouped, and the cloth feeding sequence of each group of tobacco stems can be calculated and arranged. Then, the cumulative amount of tobacco stems before washing is linked with the scraper motor, so that the scraper motor can be automatically adjusted according to the weights of each group of tobacco stems newly entered. For tobacco stems of different grades, the control system can save the corresponding data. When soaking the corresponding tobacco stems, just control the scraper motor to work according to the corresponding working parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0026] Figure 1 It is a flow chart of the continuous on-line grouped tobacco stem washing method in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0028] Embodiment 1

[0029] In a typical embodiment of the present invention, referring to Figure 1 as shown, a continuous on-line grouped tobacco stem washing method includes the following steps:

[0030] Step 1: Group the tobacco stems of each grade according to the moisture content of the tobacco stems after soaking.

[0031] Step 2: Establish a regression equation between the moisture content of each group of tobacco stems and the soaking time, and obtain the soaking time required for each group of tobacco stems to reach the same moisture content.

[0032] Step 3: Establish a regression equation between the frequency of the scraper motor of the tobacco stem washing machine and the obtained soaking time, and obtain the frequency of the scraper motor required for each group of tobacco stems.

[0033] Step 4: Link the cumulative amount of tobacco stems before washing with the obtained frequency of the scraper motor. Each group of tobacco stems is fed in the order of decreasing tobacco stem water absorption rate, and the frequency of the scraper motor is automatically adjusted according to the cumulative amount of the electronic belt scale.

[0034] In Step 1: First, according to the different water absorption rates of tobacco stems of different grades in the tobacco stem formula, the variance analysis method is used to group the tobacco stems, and the grades with no obvious difference in water absorption rate are divided into one group. The specific grouping includes the following specific steps:

[0035] (1) Simulate the production conditions of stem washing. Take 1000 g of tobacco stems of each grade respectively, place them in hot water at 60 °C for 60 seconds. Then take out the tobacco stems, drain the surface moisture, store them in an environment with a temperature of 26 °C and a humidity of 60% for 4 hours, cut the tobacco stems into slices with a thickness of about 1 mm, and use the oven method to detect the moisture content of the tobacco stems, and detect the moisture content of the tobacco stems of the corresponding grade after soaking.

[0036] (2) Conduct a significant difference analysis on the moisture content of tobacco stems of each grade detected by the oven method. Enter 30 moisture content data of each grade into the Minitab software, and use the Tukey variance analysis method. Group the grades with no significant difference in the moisture content (moisture content) of the tobacco stems. Among them, the Minitab software uses different letters to distinguish the significance of differences.

[0037] In step 2: Determine the soaking time required for each group of tobacco stems to reach the same moisture content, including the following specific steps:

[0038] (1) Take the same weight of tobacco stems of each grade in each group, that is, the mass of each group of tobacco stems is the same. When there are different grades of tobacco stems in each group, it is necessary to ensure that the mass of different grades of tobacco stems in the same group is also the same; for example, the sampling amount of each group of tobacco stems is 1000 g. After mixing evenly, place them in hot water at 60 °C for soaking. Take 100 g of samples at the 20th, 30th, 40th, 50th, and 60th seconds of soaking respectively, drain the surface moisture, store them in an environment with a temperature of 26 °C and a humidity of 60% for 4 hours, and use the oven method to detect the moisture content of the tobacco stems to obtain the moisture content of each group of tobacco stems at different soaking times.

[0039] (2) According to the moisture content of each group of tobacco stems at different soaking times, calculate the corresponding relationship between the moisture content of the tobacco stems and the soaking time, and establish a regression equation.

[0040] (3) According to the required moisture content of the tobacco stems and the established regression equation, calculate the soaking time required for each group of tobacco stems.

[0041] In step 3: Determine the corresponding relationship between the frequency of the scraper motor of the stem washer and the soaking time, including the following specific steps:

[0042] (1) Set the frequencies of the scraper motor to 5 Hz, 10 Hz, 15 Hz, 20 Hz, 25 Hz, 30 Hz, 35 Hz, 40 Hz, 45 Hz, and 50 Hz respectively. Add 1000 g of tobacco stems to the inlet of the stem washer at each frequency and start timing. Record the appearance time of the first tobacco stem and the last tobacco stem at the outlet of the stem washer respectively, and use the average value of the two as the soaking time for a single test. Repeat three times as the soaking time at each frequency.

[0043] (2) Calculate the corresponding relationship between the frequency and time according to the set frequency of the scraper motor and the soaking time of the tobacco stems at this frequency, and establish a regression equation.

[0044] (3) Combine the soaking time required for each group of tobacco stems determined in the second aspect of the present invention and the regression equation of the scraper motor frequency and the soaking time, and calculate the scraper motor frequency required for each group of tobacco stems.

[0045] In step 4: Establish a linkage program for the scraper motor frequency and the material accumulation amount, including the following specific steps:

[0046] Add an automatic control program for the scraper motor frequency of the stem washer in the control system, distribute the tobacco stems according to the water absorption rate of each group of tobacco stems from large to small, use the cumulative weight of the electronic belt scale before washing the stems as a signal, and realize the automatic adjustment of the scraper motor frequency according to the change of the tobacco stem formula level, so as to change the soaking time of each grade of tobacco stems and achieve the effect of relatively consistent moisture content of each grade of tobacco stems after washing the stems.

[0047] Specific test examples are as follows:

[0048] Step 1: Group the tobacco stems of each grade according to the moisture content after soaking.

[0049] (1) Detect the moisture of each grade of tobacco stems after soaking for the same time

[0050] Taking the Class A stem formula as an example, there are a total of 8 grades: medium-long stems in the middle of Hunan Province, medium-long stems in the upper part of Shandong Province, medium-long stems in the middle of Hubei Province, medium-long stems in the middle of Sichuan Province, medium-long stems in the middle of Shandong Province, upper-long stems in the upper part of Sichuan Province, upper-long stems in the upper part of Guizhou Province, and medium-long stems in the middle of Yunnan Province, numbered 1#, 2#, 3#, 4#, 5#, 6#, 7#, and 8# in sequence. Simulate the stem washing production conditions, take 1000 g of each of the 8 grades of tobacco stems, place them in 60 °C hot water respectively, soak for 60 seconds, take out the tobacco stems, drain the surface moisture, store them in an environment with a temperature of 26 °C and a humidity of 60% for 4 hours, and then use the oven method to detect the moisture of the tobacco stems. The moisture of each grade is detected 30 times. See Table 1 for details.

[0051] Table 1 Summary of moisture of each grade of Class A tobacco stems after soaking

[0052]

[0053]

[0054] (2) Group the tobacco stems according to the moisture of each grade of tobacco stems

[0055] Perform a significance analysis of the moisture content differences of tobacco stems of each grade detected by the oven method. Enter the 30 moisture content data of each grade in Table 1 into the Minitab software, and use the Tukey variance analysis method to perform a significance analysis of the moisture content differences of tobacco stems of each grade detected by the oven method. This method can divide each grade into several groups according to the moisture differences using different letters, and the calculation results are shown in Table 2.

[0056] Table 2 Grouping results of Tukey variance analysis

[0057]

[0058]

[0059] It can be understood that there are significant differences between the means without shared letters; the mean of the 3# grade is between B and C. Therefore, the 3# tobacco stems can be grouped with the 5# and 8# in one group, and can also be grouped with the 7#. This indicates that the moisture content of these 4 groups of tobacco stems is close and can be divided into one group. The specific grouping is shown in Table 3.

[0060] Table 3 Detailed list of classification of Class A stems

[0061] Group a Group b Group c Group d Level 2# 5#，8#，3#，7# 1# No. 4 and No. 6 Weight (kg) 400 1400 600 600

[0062] The weight of tobacco stems in each of the above groups is an example data.

[0063] Step 2: Determine the soaking time required for each group of tobacco stems to reach the same moisture content. The method is as follows:

[0064] (1) Sample preparation

[0065] Group a has a total of 1 grade, and 1000 g of samples are taken; group b has 4 grades, and 250 g of samples are taken from each of the 5#, 8#, 3#, and 7# grades and mixed evenly; group c has 1 grade, and 1000 g of samples are taken; group d has a total of 2 grades, 4# and 6#, and 500 g of samples are taken from each grade and mixed evenly;

[0066] The 4 groups of samples are respectively soaked in hot water at 60 °C. For each group of samples, 100 g of samples are taken at the 10th second, 20th second, 30th second, 40th second, 50th second, 60th second, 70th second, 80th second, 90th second, and 100th second of soaking. After draining the surface moisture and storing for 4 hours in an environment with a temperature of 26 °C and a humidity of 60%, the moisture content of the tobacco stems is detected by the oven method. The details are shown in Table 4.

[0067] Table 4 Detailed list of moisture content of tobacco stems in each group at different soaking times

[0068]

[0069]

[0070] (2) Establish a regression equation

[0071] The soaking time and the moisture data of groups a, b, c, and d in Table 4 were respectively input into the Minitab software. Through regression analysis, a regression equation for the corresponding relationship between the moisture content of tobacco stems and the soaking time was established, and the results are as follows:

[0072] Moisture content of group a = 28.9 + 0.0729 × soaking time;

[0073] Moisture content of group b = 26.9 + 0.0628 × soaking time;

[0074] Moisture content of group c = 25.5 + 0.0690 × soaking time;

[0075] Moisture content of group d = 24.6 + 0.0748 × soaking time;

[0076] (3) Calculate the soaking time required for each group of tobacco stems

[0077] Since the required moisture content of the first-class tobacco stems after washing is 30%, according to the established regression equation, substituting the moisture content of 30% into the equation "Moisture content of group a = 28.9 + 0.0729 × soaking time", that is, 30 = 28.9 + 0.0729 × soaking time, the soaking time required for the tobacco stems in group a is calculated to be 15 seconds. Similarly, the soaking times required for the tobacco stems in groups b, c, and d can be calculated to be 49 seconds, 65 seconds, and 72 seconds respectively.

[0078] Step 3: Determine the required scraper motor frequency for each group of tobacco stems, including the following specific steps:

[0079] (1) Determine the soaking time of tobacco stems at different scraper motor frequencies

[0080] The scraper motor frequencies were respectively set to 5Hz, 10Hz, 15Hz, 20Hz, 25Hz, 30Hz, 35Hz, 40Hz, 45Hz, and 50Hz. 1000g of tobacco stems were added at the inlet of the tobacco stem washer at each frequency and timing was started. The times when the first and the last tobacco stems appeared were respectively recorded at the outlet of the tobacco stem washer, and the average value of the two was used as the soaking time for a single test. The average value was taken after repeating three times as the soaking time at each frequency. The results are shown in Table 5.

[0081] Table 5 Details of the soaking time of tobacco stems at different frequencies

[0082] Serial number Frequency (Hz) Time 1 (s) Time 2 (s) Average (s) 1 5 107 110 108.5 2 10 99 102 100.5 3 15 92 94 93 4 20 78 80 79 5 25 71 73 72 6 30 59 62 60.5 7 35 47 49 48 8 40 38 40 39 9 45 26 29 27.5 10 50 15 19 17

[0083] (2) Establish a regression equation for the scraper motor frequency and the soaking time

[0084] The 10 groups of data of the frequency and the average time in Table 5 were respectively input into the Minitab software. Through regression analysis, a regression equation for the corresponding relationship between the scraper motor frequency and the soaking time of tobacco stems at this frequency was established, and the results are as follows:

[0085] Time = 121 - 2.07 Frequency

[0086] (3) Determine the required frequency of the scraper motor for each group of tobacco stems

[0087] Substitute the soaking times required for each group of tobacco stems determined in step 2: 15 seconds for group a, 49 seconds for group b, 65 seconds for group c, and 72 seconds for group d into the equation "Time = 121 - 2.07 Frequency" to calculate the required frequencies of the scraper motors for each group of tobacco stems as follows: 51 Hz for group a, 35 Hz for group b, 27 Hz for group c, and 24 Hz for group d. Since the maximum motor frequency is 50 Hz, the frequency of the scraper motor for group a is set to 50 Hz.

[0088] Step 4. Optimize the control system

[0089] The scraper motor here uses a Danfoss frequency converter and communicates with the Siemens 400 CPU of the centralized control system through a PN network interface. The electronic scale and the PLC of the centralized control system also use the PN network communication method to transmit the cumulative amount of the electronic belt scale to the centralized control system in real time. The monitoring interface (Intouch) sets the cumulative amounts of different groups and the corresponding motor frequencies used. When the corresponding cumulative amount is reached, the PLC program automatically triggers the change of the motor frequency. See Table 6 for details

[0090] Table 6 Details of the cumulative amount of the electronic belt scale and the frequency of the scraper motor

[0091] Grouping Group a Group b Group c Group d Accumulated quantity of electronic belt weigher (kg) 0 400 1800 2400 Frequency of scraper motor (Hz) 50 35 27 24

[0092] It can be understood that an optoelectronic metering tube is provided above the electronic belt scale to control the stability of the tobacco stem flow rate.

[0093] The method for washing tobacco stems in groups of the present invention is as follows

[0094] 1) Arrange the tobacco stem formula grades in descending order of water absorption rate

[0095] 2) Enter the weight of each group of tobacco stems into the control system according to the water absorption rate of different groups of tobacco stems

[0096] 3) Start the equipment and distribute the materials in the arranged order of the tobacco stems

[0097] 4) During the tobacco stem washing process, when the grades alternate, the frequency of the scraper motor of the washing machine is automatically adjusted according to the weight of each grade of tobacco stems entered; by matching the cumulative weight of the electronic belt scale before washing the tobacco stems with the tobacco stem formula, the weight of each grade of tobacco stems in the tobacco stem formula is entered into the control system to achieve online identification of the replacement of tobacco stem grades

[0098] 5) When the tobacco stem formula is adjusted, rearrange it according to method 1) and update the data of method 2)

[0099] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A continuous online grouping stem washing method, characterized in that: The steps include: Step 1: grouping tobacco stems of different grades according to their moisture content after soaking; Step 2: Establish a regression equation between the moisture content of tobacco stems in each group and the soaking time, and obtain the soaking time required for the tobacco stems in each group to have the same moisture content; Step 3: Establish a regression equation between the scraper motor frequency of the stem washer and the obtained soaking time to obtain the scraper motor frequency required for each group of tobacco stems; Step 4: Link the accumulated amount of tobacco stems before washing with the obtained scraper motor frequency, feed each group of tobacco stems in order from large to small according to the water absorption rate of the tobacco stems, and the scraper motor frequency is automatically adjusted according to the accumulated amount of the electronic belt scale.

2. A continuous online grouping stem washing method according to claim 1, characterized in that: In step 1, tobacco stems of the same mass of each grade are taken and immersed in hot water under set conditions, and then the tobacco stems are taken out, processed and the moisture content of the tobacco stems is tested to obtain the moisture content of the tobacco stems of the corresponding grade.

3. A continuous online grouping stem washing method according to claim 1 or 2, characterized in that: The variance analysis method was used to analyze the significant differences in the moisture content of tobacco stems of various grades tested, and then the grades with no significant difference in the moisture content of tobacco stems were divided into one group.

4. A continuous online grouping stem washing method according to claim 1, characterized in that: In step 2, the same mass of tobacco stems is taken from each group, and the mass of tobacco stems of different grades in each group of tobacco stems is ensured to be the same. The tobacco stems are soaked under set conditions. The tobacco stems of each group are taken out after different soaking times and the moisture content is tested. According to the moisture content of each group of tobacco stems at different soaking times, the corresponding relationship between the moisture content of the tobacco stems and the soaking time is calculated, and a regression equation is established. According to the required moisture content of the tobacco stems and the established regression equation, the soaking time required for soaking each group of tobacco stems until the moisture content is the same is obtained.

5. A continuous online grouping stem washing method according to claim 4, characterized in that: In step 3, multiple scraper motor frequencies are set respectively, and a set mass of tobacco stems are added from the inlet of the stem washer at each frequency, and timing is started. The time when the first and last tobacco stems appear at the outlet of the stem washer are recorded respectively, and the average value of the two groups of time is used as the immersion time for a single test.

6. A continuous online grouping stem washing method according to claim 5, characterized in that: According to the set scraper motor frequency and the tobacco stem soaking time at the corresponding frequency tested, the corresponding relationship between frequency and time is calculated and a regression equation is established; the soaking time required for each group of tobacco stems determined in step 2 is substituted into the regression equation to obtain the scraper motor frequency required for each group of tobacco stems.

7. A continuous online grouping stem washing method according to claim 1, characterized in that: In step 4, an automatic frequency control program for the scraper motor of the stem washer is added to the control system of the stem washer. After that, the tobacco stems of each group are distributed from large to small according to the water absorption rate. The accumulated weight of the electronic belt scale before stem washing is used as a signal to realize automatic adjustment of the scraper motor frequency according to the changes in the distribution of tobacco stem groups.

8. A continuous online grouping stem washing method according to claim 7, characterized in that: The weight of each group of tobacco stems is entered into the control system according to the water absorption rate, and then the stem washing machine is started to spread the tobacco stems in the order of the arranged groupings.

9. A continuous online grouping stem washing method according to claim 8, characterized in that: When the tobacco stem recipe is adjusted, the order of the fabrics needs to be rearranged.

10. A continuous online grouping stem washing method according to claim 9, characterized in that: After rearranging the order of the fabrics, the weight of each group of tobacco stems needs to be re-entered.

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