Process Optimization to Reduce Sucrose Loss with Final Molasses: The case of Metahara Sugar Factory

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa University


In this study, process Optimization has been applied to D-massecuite boiling, cooling crystallization, reheating and separation processes in MSF to minimize the high sucrose loss with final molasses. Mother liquor purity and Purity drop were taken as response variables to measure the performance of each process towards minimization of final molasses purity. Design Expert-Response surface methodology was applied to statistically evaluate the data and to solve optimum values factors and response variables. Economical advantages of the process optimizations were compared with the factory’s existing working norms. D- massecuite boiling optimization has resulted in nutsch purity reduction of 0.53 units. Similarly, an increase in purity drop of 0.80 (from 4.21 to 5.01) across cooling crystallizers was obtained at optimum cooling time of 17.36h and temperature to 450C for the existing crystallizer’s capacity. The cooling experimental results have indicated that a purity drop of 6.37 units can be achieved if crystallizer capacity of MSF increased so as to give cooling time of 34.5h and temperature of 440C. For the existing reheaters, the optimum reheating temperature was found to be 52.50C which gave a purity rise across reheaters of 0.530 against the value of 0.97 before optimization and the optimum massecuite flow rate of 19t/h. From the centrifugal separation optimization result, the optimum spray water was found to be 6.3% massecuite giving a purity rise of 2.44 across centrifugal machines and DFW magma purity of 84.0. The overall effect of process optimization was a reduction in final molasses purity by 1.43 units (from 34.86 to 33.43) for the existing capacity of cooling crystallizer which leads to annual saving of 1040.5 tons sugar, equivalent to 13,526,919 Birr. Additional saving of 12,334825birr/year is expected if enough crystallizer capacity is installed for MSF. Key words: Final Molasses, Sucrose Loss, Purity, Purity Drop, Exhaustion, Response Surface Methodology



Final Molasses; Sucrose Loss; Purity, Purity Drop; Exhaustion; Response Surface Methodology