Dissertation
Dissertation > Industrial Technology > Light industry,handicrafts > Tobacco Industry > Tobacco early processing > Tobacco redrying

Evaluation on Stability of Threshing and Redrying Lamina Structure of Tobacco

Author WangMan
Tutor XuZiCheng
School Henan Agricultural University
Course Tobacco science
Keywords Tobacco Threshing and redrying Lamina strucuture stability Statistical process control Multivariate statistical process control Lamina storerome Processing parameters
CLC TS443
Type Master's thesis
Year 2011
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Threshing and redrying can serve as a bridge between tobacco leaves and cigarette. Lamina structure was important to tobacco quality and was vital to stabilize development continuously for cigarette. The evaluation on stability of lamina structure was of critical concern fort threshing and redrying factory and cigarette industrial enterprise. In this paper the stability of lamina structure were studied from ten threshing and redrying factories of China by integrating grey theory, the mathematical statistics theory and statistical process control. Main results were as follows.1. It was difficult for evaluate quality because of numerous lamina structure index.To solve the problem,the test analyzed nine routine lamina structure index of 295 samples from main ten threshing and redrying factories of China by systematic cluster analysis and grey relational degree cluster analysis. What is more , the representative indicators from the cluster results were selected by infinite irrelevance with the requirements for indicators system optimization which were purpose, maneuverability and hierarchy. The results showed that: the content of long particle (>12.7mm), stem content , medium partical(12.7mm-25.4mm) content and small partical(6.35mm-12.7mm)content were selected as the representative indications of lamina structure. The selection of representative indicators was used for lamina quality evaluation. The whole process need to combine quantitative analysis with qualitative analysis and integrate theory with practice and follow the objectivity.2. In order to explore the distribution of lamina structure and the influence of various factors on lamina quality, the 290 lamina samples, from ten threshing and redrying factories from 2008 to 2010, were analyzed. The distribution and differences of lamina structure of different years、different grades、different batches、pre and post redrying and different threshing and redrying factories were analyzed and the variability of various indexes of lamina structure was described. The results showed that there was difference in different years and the content of long particle (>12.7mm) of supper lamina and middle lamina was improved, but small partical content and stem content was reducing year by year. There was difference in different grades. The difference between supper lamina and middle lamina was small and there was significant difference between the content of long particle (>12.7mm) and small partical content of supper lamina and supper lamina and middle lamina. Processing levels of lamina showed the order of supper lamina > middle lamina > upper lamina. There was difference in different batches and there was extremely significant difference before and after redrying. There were different differences among different threshing and redrying factories. The difference of the content of long particle (>12.7mm) was weak and other indexes of lamina structure were middle.3. The stability threshing and redrying lamina structure was evaluated by different evaluation methods.(1) The stability degree of lamina structure was is divided by Analytic Hierarchy Process and systematic cluster analysis. Stability of lamina structure was evaluated from Sanyi, Enshi and Yunnan from 2008 to 2009 by coefficient of variation. The results showed that the stability of the content of long particle was better than percentage of middle lamina and percentage of small lamina and stem content in lamina. The stability of lamina overall quality in Sanyi was better than Enshi and Yunnan.(2) In order to explore the stability of lamina structure of threshing and redrying, eleven structure indexes of 295 samples from twenty tobacco redrying factories were analyzed by grey statistic analysis method. The results showed that percentage of middle lamina (12.7mm~25.4mm) and percentage of small lamina (6.35mm~12.7mm) belonged to unstable indexes, which most deviated from the target requirement. Dust rate and crude stem rate and the content of long particle (>12.7mm) and the percentage of lamina(>6.35mm) and the percentage of lamina(>3.18mm) belonged to slightly stable indexes and more deviated from the target requirement. The variation of moisture content and percentage of large lamina (>25.4mm) and fine particle content (1mm~6.35mm) and stem content in lamina were stable ,which accorded with requirements. The grey statistical coefficient was tested by Variance Analysis, thus the indexes threshold value should be reasonable. The percentage of middle lamina should be improved and percentage of small lamina should be decreased mainly and the slightly stable indexes should be paid attention to and the stable indexes should be continued for quality evaluation and process control.(3) Diffierent batches Lamina CAAF3 indexes in 2009 including the content of long particle, percentage of middle lamina and percentage of small lamina were studied from Yunnan tobacco leaf company by gray association degree classification analysis theory. The number of classes was different ifλwas differdnt. It would be small ifλwas small. The less classes was, the better stability of batch was with the sameλ.(4) The compliance of content of long particle and stem content in 2009 from Yunnan tobacco leaf company was studied. The restlt showed that: their compliance was different if the grade was different. Lamina grade 143,144,145,217and 218 corresponds with tobacco industry needs and othes were poor. The compliance of content of long particle was better than stem content.(5) The stability of threshing and redrying lamina structure was evaluated from Yunnan between the year of 2008 and 2009. The lamina stability in the same batch could be studied by Single factor analysis of variance and significant test. It could test quality fluctuation effectively. Overall, it was stable for grade 142, 144, 219 and CXBF.(6) In order to understand the comprehensive stability of lamina structure from different threshing and redrying factories, the stability of lamina samples which were from ten threshing and redrying factories in our country was analyzed by grey relation analysis method and system cluster. The results showed that: the comprehensive stability of lamina structure from different threshing and redrying factories, from big to small, was E > F > H > D > G > C > A > B > I > J; the correlation level of grey correlation degree between relevant sequences that were threshing and redrying factories and the optimal sequence was as follows: the correlation level between E and the optimal sequence reached remarkable level and F, H, D reached significant level and others is not significant; the system cluster results were following: F, H, D as a class had good stability and G, C, A, B and I as a class had poor stability and J as a class had more poor stability.4. Threshing and redrying process lamina stability was controlled by gray theory.(1) In order to the stability controlling of lamina structure in the process of threshing and redrying, the lamina samples CAAF3, from Yunnan province threshing and redrying factory in 2010, were analyzed by statistical process control. The control chart’s analysis moment and control moment were made and the judgement of steady state and the analyses of process capability were made. The results showed that the samples of group 3 and group 5 were unstable and the process capability was lower ( Cpk =0.36). It was a major concern to improve process capability for threshing and redrying factory. Statistical process control was effective for lamina structure control and detection and it could satisfy the demands for the tobacco industry.(2) In order to implement the process monitoring for various indexes of lamina structure at the same time and ensure the stability of lamina quality, the lamina samples , from Yunnan province threshing and redrying factory in 2009,were analyzed by multivariate statistical process control .The stability of the three indexes of lamina structure was judged by T 2diagram of multivariate statistical process control and every uncontrolled group variables were tested. The results showed that multivariate statistical process control could be applied in threshing and redrying process and many variables could be monitored simultaneously by T 2diagram of multivariate statistical process control and Bonferroin test have some reference value for finding the uncontrolled variables. 5. The effects of lamina storerome and processing parameters on stability of lamina structure were analyzed. The result showed that: lamina storerome density could affect lamina structure. The higher its density was, the lower percentage of content large lamina and content of long particle, but fine particle content would be rising. Threshing and redrying processing parameters had effect on stability of content of content of long particle. It would be different if processing parameters was different. The first threshing processing parameters had a great important to content of long particle.

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