Paola Bastidas, Alejandro Villegas, Alexander Moreno and Jhon Jerez
Providencia, km 12 Palmira – El Cerrito, Colombia;pabastidas@providenciaco.com
High solid content in the mash column feed in ethanol distilleries leads to clogging of the upper stages, resulting in ethanol losses and mash carryover. This issue demands a 24-hour plant shutdown for manual cleaning, which increases steam consumption, impacts performance indicators, and reduces column availability. To address these challenges, simulations were conducted using Aspen Plus to analyze the current column operation and propose a design modification to extend continuous operating time. The RadFrac model was selected, coupled with the NRTL-RK thermodynamic method, to accurately replicate the column’s behavior. Sensitivity analyses were performed to assess the impact of varying the number of stages and the feed stage on ethanol content at the bottom, outlet purity, and energy consumption. The simulation results indicated that the oversized design of the column allows flexibility in modifying the feed stage without incurring ethanol losses at the bottom. By adjusting the feed stage during clogging, the column maintained ethanol purity levels while improving overall operational stability. Adding auxiliary inlet stages, that activate when clogging occurs at the initial stage, extended the continuous operational time of the column by 8 to 15 days. This modification also led to improved steam consumption and column availability. Based on these findings, it is concluded that the use of process simulators, such as Aspen Plus, is invaluable in accurately replicating plant behavior and testing modifications before implementation, thereby reducing the risk of operational disruptions. Moreover, having the ability to extend operating time without incurring ethanol losses or downtime is a crucial advantage for plant productivity.