tailieunhanh - ANALYSING CROSS DIRECTIONAL CONTROL IN FINE PAPER PRODUCTION

It has been demonstrated that most heavy metals that are in the fuels or raw materials used in cement kilns are effectively incorporated into the clinker, or contained by standard emissions control devices (WBCSD 2002; European Commission (EC) 2004; Vallet January 26, 2007). A study using the EPA’s toxicity characteristic leaching procedure to test the mobility of heavy metals in clinker when exposed to acidic conditions found that only cadmium (Cd) could be detected in the environment, and at levels below regulatory standards (5 ppm) (Shih 2005). As long as cement kilns are designed to meet high technical standards,. | 2006 074 CIV EXAMENSARBETE Analysing Cross Directional Control in Fine Paper Production TAREK EL-GHAZALY ERIK JONSSON MASTER OF SCIENCE PROGRAMME Industrial Management and Engineering Luleâ University of Technology Department of Business Administration and Social Sciences Division of Quality Environmental Management UNIVERSITET 2006 074 CIV ISSN 1402 - 1617 ISRN LTU - EX - - 06 74 - - SE Analysing cross directional control in fine paper production Stora Enso Research Centre in Falun By Tarek El-Ghazaly Erik Jonsson Falun 2006-01-15 Supervisors Mats Hiertner Stora Enso Research Centre Falun Erik Lovén Luleả University of Technology Abstract A perfect paper machine would not need any control action. However defects in the production process and disturbances in raw material cause instability which requires control actions. The compensations made in the controlled variables often cause variations in other properties. In order to produce a perfect product without variations in any properties the goal must be to eliminate the defects and disturbances causing control action. By studying the actions from the control system it is possible to identify the defects in the process. In order to further investigate the potential of studying the output from the control system a study was made for a Fine Paper machine PM9 at Grycksbo Mill . In this thesis a number of cross profile controls were studied simultaneously. Another interesting approach to identify primary causes of disturbances is by implementing an online analysis. This thesis shows that variance component analysis can be used to identify periods when the control action is unusually high. The authors believe that the best results can be reached if the variance component analysis is applied on data from one to three hours. In order to be able to estimate alarm limits the slower variations in control activity need to be filtered out. This is done with EWMA. The usage of variance component analysis makes an implementation