Extraction parameters optimization in improving production rate of spent bleaching earth oil

Abstract

Spent bleaching earth (SBE) is classified as an industrial waste generated by almost all crude palm oil refineries around the globe. SBE contains oil content in the range of 20-40% by weight, which is being extracted out by a solvent extraction process plant to cater for biodiesel production. Most of the current studies are focusing on the optimization of various plants and seeds extraction parameters based on a laboratory scale. Hence, a study on the optimization of the solvent extraction parameters conducted on an actual industrial-scale production plant is the key element for an enhanced SBE oil extraction process plant management. This study shall pioneer in optimizing the extraction parameters to enable plant managers to monitor the inputs and outputs of each plant equipment to operate the plant efficiently. In this study, the extraction parameters, namely, settling rate, n-hexane temperature, and slurry concentration were optimized by response surface methodology using Box-Behnken Design (BBD) to improve the extraction oil rate. The independent variables, settling rate (13 ml, 11 ml, and 8 ml), n-hexane temperature (45 °C, 50 °C and 55 °C), and slurry concentration (30%, 35%, and 40%) were selected for optimization at three-factorial levels and their values were selected based on the extraction plant current operating condition and limitation. The BBD consisted of 17 experimental actual production plant runs with 3 hours of continuous process control with a steady-state operation for each run. A second-order polynomial model was used for predicting the responses’ outcomes. Analysis of variance of the conducted experimental runs concluded that 96.9% of the variation was explained by the models. The optimized extraction parameters were 13 ml, 55 °C, and 30%, for settling rate, n-hexane temperature, and slurry concentration, respectively. Under the optimized extraction parameters, the values of the corresponding response was 2.080 tons per hour. Mass balance computation, which was conducted with the aid of SuperPro Designer® software, resulted an improved extraction oil rate of 2.086 tons per hour which was an improvement of 9% as a result of the optimization conducted the studied production plant.