Characterization of Multiple Effect Evaporators?�? Scale in New Wonji/Shoa Sugar Factory, Ethiopia

Abstract

Scale formation in Multiple Effect Evaporator (MEE) systems is the main unsettled challenge, which is encountered in new Wonji/Shoa sugar factory. Thus, the present study attempted to Characterize Multiple Effect Evaporators’ scale in New Wonji/Shoa Sugar Factory, Ethiopia. Micro-Plasma Atomic Emission Spectroscopy (MP-AES) was used to characterize Mg, Si, Fe, and Al. Moreover, Ethiopian Standards (ES 817:2012) was used to determine total solids in clarified juice. Different Standard methods to characterize the clarified water, and evaporators’ scale.Minitab Statistical Software, Version 19.1.1 was used for one-way ANOVA test. The Clear juice analysis result revealed that only total solid (19.14 ± 0.32 % w/w) and CaO content (>500 ppm) is high as compared to the standard value (20 -150 mg/L).One-way ANOVA result of CaO versus months revealed that there was very highly significant variation (P < 0.001) between months. The clarified water analysis result was within the standard set by WHO, except the fluoride content (3.57 ± 0.06 mg/L) which is double the European Union (EU) surface water value (1.7 mg/L). The scale collected from new WSSF multiple effect evaporators was analyzed for SiO2, Fe2O3, CaO, MgO, Na2O, MnO, P2O5, TiO2, H2O, and Loss on ignition (LOI) using different analytical methods. Except the case for TiO2 (P > 0.05), all the parameters revealed very highly significant variation (P <0.001) between five evaporators. Moreover, the experimental result of MEEs’ scale has shown that SiO2 and Fe2O3 increased from first evaporator to fifth evaporators. CaO, P2O5, and LOI of the scale sample are decreasing from first evaporator to the fifth evaporator. The analysis of scale result shown the first evaporators have high content in CaO, P2O5, and total volatile substances. From the analysis result, the source of scale is solely from the clear juice obtained from clarification process and is the source of CaO, P2O5, and high content of organic matters/volatile substances. Therefore, new WSSF should apply an efficient clarification system primarily to reduce the scale formation.