Dead Time Compensation in Sugar Crystallization Process
The input to the sugar factory is the sugarcane billets and the output is the crystal sugar. There are many subprocesses with significant multivariable interaction involved within this process which is cane preparation, juice extraction by crushing mill,
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Abstract The input to the sugar factory is the sugarcane billets and the output is the crystal sugar. There are many subprocesses with significant multivariable interaction involved within this process which is cane preparation, juice extraction by crushing mill, heating, clarification and filtration, evaporation, and crystallization. In the present paper, the Smith predictor is designed using MATLAB in order to compensate the dead time present in heat exchanger system of the crystallization process and its performance is compared to that of a conventional PI controller with no dead time compensation. Keywords Smith predictor
Crystallization Dead time Disturbance rejection
1 Introduction The extracted juice from the crushing mill is clarified and evaporated. The resulting syrup is then sent to the crystallization process. The flow diagram of the crystallization process, which is found in sugar factories are shown in Fig. 1. The objective is to maximize the crystal growth speed with minimum cost and losses. Vacuum boiling pans are used for crystallization in which the syrup is boiled until it gets supersaturated. A sucrose solution is said to be saturated if it contains two parts of sucrose to one part of water at room temperature and five parts S.K. Sunori (&) Graphic Era Hill University, Bhimtal, Uttarakhand, India e-mail: [email protected] P.K. Juneja Mayank Chaturvedi Jeevanshi Mittal Graphic Era University, Dehradun, Uttarakhand, India e-mail: [email protected] Mayank Chaturvedi e-mail: [email protected] Jeevanshi Mittal e-mail: [email protected] © Springer Science+Business Media Singapore 2017 R. Singh and S. Choudhury (eds.), Proceeding of International Conference on Intelligent Communication, Control and Devices, Advances in Intelligent Systems and Computing 479, DOI 10.1007/978-981-10-1708-7_43
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Fig. 1 Vacuum pan [1]
of sucrose to one part of water at 100 °C. If the concentration of sucrose is raised above this value, then it becomes supersaturated which is essential for crystallization to take place [2]. Now, the sugar crystals suspended in alcohol are added to it. These crystals behave as seed crystals. Sucrose gets deposited around these crystals. These crystals then grow in size. The sugar liquor is generally boiled in three stages A, B, and C. The mixture containing syrup and sugar crystals which is called massecuite is evaporated until supersaturation takes place in vacuum pan ‘A’. Now the centrifuging of this mixture is done at a high speed which separates the sucrose crystals from the syrup. The residual syrup is passed to ‘B’ vacuum pan where the same crystallization process is repeated. The sugar that is recovered from ‘B’ pan is added to the concentrated syrup fed to ‘A’ pan. The machine syrup of ‘B’ pan is passed to ‘C’ pan where it is again subjected to the crystallization process. The sugar that is recovered from ‘C’ pan is added to the concentrated syrup fed to ‘B’ pan. The machine syrup of ‘C’ pan is passed to the purifier
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