Browse > Article

Model Predictive Control of the Melt Index in High-Density Polyethylene(HDPE) Process  

Lee, Eun Ho (Department of Chemical Engineering, Hanyang University)
Kim, Tae Young (Department of Chemical Engineering, Hanyang University)
Yeo, Yeong Koo (Department of Chemical Engineering, Hanyang University)
Publication Information
Korean Chemical Engineering Research / v.46, no.6, 2008 , pp. 1043-1051 More about this Journal
Abstract
In polyolefin processes melt index (MI) is the most important controlled variable indicating product quality. Because of the difficulty in the on-line measurement of MI, a lot of MI estimation and correlation methods have been proposed. In this work a new dynamic MI estimation scheme is developed based on system identification techniques. The empirical MI estimation equation proposed in the present study is derived from the $1^{st}$-order dynamic models. Effectiveness of the present estimation scheme was illustrated by numerical simulations based on plant operation data including grade change operations in high density polyethylene (HDPE) processes. From the comparisons with other estimation methods it was found that the proposed estimation scheme showed better performance in MI predictions. Using the model predictive control method based on the present dynamic MI estimation model, MI values are estimated and compared with those of MI setpoints. From the numerical simulation of the proposed control system, it was found that significant reduction of transition time and the amount of off-spec during grade changes were achieved.
Keywords
Polyethylene; Melt Index; Dynamic Model; Grade Change; Model Predictive Control; Quality Control;
Citations & Related Records
연도 인용수 순위
  • Reference
1 Oh, S. J., Lee, J. S. and Park, S. W., 'Prediction of Pellet Properties for an Industrial Bimodal High-density Polyethylene Process With Ziegler-natta Catalysts,' Ind. Eng. Chem. Res, 44, 8-20(2005)   DOI   ScienceOn
2 McAuley, K. B. and MacGregor, J. F., 'Nonlinear Product Property Control in Industrial Gas-phase Polyethylene Reactors,' AIChE J., 39, 855-866(1993)   DOI   ScienceOn
3 McAuley, K. B. and MacGregor, J. F., 'On-line Inference of Polymer Properties in an Industrial Polyethylene Reactor,' AIChE J., 37, 825-835(1991)   DOI
4 Ogawa, M., Ohshima, M., Morinaga, K. and Watanabe, F., 'Quality Inferential Control of an Industrial High Density Polyethylene Process,' Journal of Process Control, 9, 51-59(1999)   DOI   ScienceOn
5 Ohshima, M. and Tanigaki, M., 'Quality Control of Polymer Production Processes,' Journal of Process Control, 10, 135-148(2000)   DOI   ScienceOn