International Journal of Modern Trends in Engineering and Research e-issn No.: , Date: 2-4 July, 2015

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1 International Journal of Modern Trends in Engineering and Research e-issn No.: , Date: 2-4 July, 2015 Optimization of Evaporation Process in Sugar Industry for Developing Intelligent Control Strategies Sebastian George1, Devendra N. Kyatanavar2 1 Department of E &TC Engineering, SRES s College of Engineering, Kopargaon , MS, India, seb.jessy@rediffmail.com 2 Principal, SRES s College of Engineering, Kopargaon , MS, India Abstract Production of sugar contains a number of unit operations, out of which the most energy consuming one is the evaporation process. The evaporators used in sugar industries have multiple effects connected in series. It is used to raise the concentration of sugar cane juice from a nominal value. While developing the control strategies for such systems, two major objectives to be considered are concentration of sugar cane juice and steam economy. In this paper, the development of a simulation model of an evaporator having four stages is attempted. The model is developed in MATLAB based on the mass and energy balance at different effects. For proper understanding of the evaporator dynamics and validation of simulation model, data are collected from different sugar factories located in the state of Maharashtra, India. For analyzing the evaporation process, the simulation model is subjected to a set of trials for different values of feed temperature and mass flow rates of steam and feed. The model is further optimized using Taguchi technique. The optimized model can be used for analysis and synthesis of intelligent control strategy on which research is in progress. Keywords- concentration of sugar cane juice; evaporation process; optimization; steam economy, taguchi technique. I. INTRODUCTION Sugar is India s second largest agro-processing industry and India is among the largest producers and consumers of sugar in the world. About 45 million Indian farmers and their families are dependent on the cultivation of sugar[1]. Production of sugar from sugar cane route has been an age of old practice and the technology has been fairly stabilized in India for quite some time. Sugar plant automation packages are available now a days for improving Steam Fuel economy and quality of sugar. Juice flow stabilization system, Lime Sulphitation ph control system, Vapour stabilization system etc. are examples of such packages. Vapour stabilization system is meant for automatic control and maintaining rate of vapour to the pan section. In a sugar plant, due to non conventional operations of batch pans, the pan floor steam consumption will always be a fluctuating demand [4]. It will affect the functioning of evaporator stations by disturbing the pressure difference of respective bleeding effects and also preceding effects. With fluctuating demand of pans, the vapor pressure in second effect followed by first effect tends to fluctuate which ultimately affect the exhaust steam pressure. These fluctuations in exhaust and vapor pressure affect the rate of evaporation in first and second effect bodies, thus resulting in fluctuations in syrup brix which further causes variation in steam demand at pan stations. This 998

2 further aggravates the fluctuation in the vapour and exhaust steam pressures. Thus it becomes a vicious cycle. II. MULTIPLE EFFECT EVAPORATOR Out of a number of unit operations involved in sugar production, the most energy consuming unit is the evaporation process [2]. The main function of evaporator is to raise the concentration (brix ) of sugar cane juice from a nominal value of say, 15 wt % to syrup with the brix of 72 wt %. As such, the economy of sugar manufacturing depends strongly on the evaporation process because of the huge amount of thermal energy (steam) required during the process. 2.1 MEE Dynamics The evaporator process under study here has four effects as shown in Figure 1. Each effect in the process is represented by a number of variables which are related by the mass and energy balance equations for the feed, product and vapor flow for forward feed [5]. There are two basic equations of mass and energy balance which are solved for each effect to get the values of mass flow rate of product ( mp ) and total water evaporated ( me ). Figure. 1 Quadruple Effect Evaporator 999

3 2.2 Modeling The quadruple effect evaporator system used at Bhogawati Sugar Industry, Kolhapur, MS, India has been studied extensively and observations are carried out on all the four effects. A Simulink model based on the mass and energy balance equations has been prepared and tested. Figure 2 shows the same. Figure. 2 Simulink Model Table 1 summarizes the brix values for different mass flow rates of steam. Sr. No Table No. 1. Concentration for different steam mass flow rate Ms % Sr. Ms % Concentration No. Concentration Table 2 shows the input output values obtained from the model which are in tune with the actual values obtained from the Bhogawati Sugar Industry. 1000

4 Table 2. Input output values III. OPTIMIZATION In fact, the model does not predict reasonable steady state values of the output variables as measured on the actual plant. It is therefore necessary to tune the model parameters to get reasonable steady state predictions [3]. Due to severe mass and energy interaction among the effects, this model tuning is very difficult. An approach based on Taguchi technique has been used to extract the plant parameters and optimize the model. 3.1 Taguchi Technique Tagauchi technique is a statistical method initially developed for improving the quality of goods manufactured. Later its application was expanded for many other fields in Engineering. This technique involves identification of proper control factors to obtain the optimum results of the process [6]. Orthogonal Arrays are used to conduct a set of experiments and these experiments are used to analyze the data and hence optimize the model. Here an attempt has been made to demonstrate the application of Taguchi technique to improve steam economy and concentration (brix) of sugar cane juice. 3.2 Taguchi Trails Figure 3 shows the trials carried out on the Simulink model based on the Taguchi L9 Orthogonal arrays shown in Table 3. The parameter values for this trials are given in Table 4. Table 3. Taguchi L9 Orthogonal array Feed Temp(0C) Ms (kg/hr) Mf (kg/hr) Trial No Trial No Trial No Trial No Trial No Trial No Trial No Trial No Trial No

5 Table 4. Process parameters Level Parameters Feed Temp Ms Mf

6 Figure 3. Taguchi Trials IV. RESULTS Table 3 summarises the results of Taguchi trials based on the L9 Orthogonal array. Analysis of variance for brix as well as steam economy has been carried out for the optimization of the quadruple effect evaporator model. 1003

7 Table 3. Final results V. CONCLUSION A mathematical model of quadruple effect evaporator is developed in Simulink and it has been optimized using Taguchi technique. Advanced automatic control is an important factor to optimize the MEE[4]. The main objective to minimize the energy consumption can be achieved by the development of new control scheme using soft computing tools like Fuzzy logic, Neural networks and Genetic algorithms. The optimized model developed here should be tested under such control environments on which further research will be carried out. REFERENCES [1] [2] [3] [4] [5] [6] Amitabh Sen, India s Sugar Industry, S. Lissane Elhaq, F. Giri and H. Unbehauen, The Development of Controllers for a Multiple-Effect Evaporattor in Sugar Industry, Arvin V. Pitteca, Robert T. F., Ah King and Harry C. Rughooputh, Parameter Estimation of a Multiple-Effect Evaporator by Genetic Algorithms, Proc. Joint 2nd International Symposium on Advanced Intelligent Systems, Yokohama, Japan, September 21-24, Arvin V. Pitteca, Robert T. F., Ah King and Harry C. Rughooputh, Intelligent Controller for Multiple Evaporator in Sugar Industry, Procceedings of IEEE International Conference on Industrial Technology pp , 2004 Dhara J. Shah, C. G. Bhagchandani, Design, Modeling and Simulation of Multiple Effect Evaporators, International Journal of Scientific Engineering and Technology, Vol. 1, Issue 3, pp , Srinivas Athreya, Y. D. Ventatesh Application of Taguchi Method For Optimization of Process Parameters In Improving The Surface Roughness of Lathe Facing Operation International Refereed Journal of Engineering and Science, Vol. 1, Issue 3, pp ,

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