Reduction of sugarcane stillage generation through Heat-Integrated Distillation and Evaporation (HIDiE)

Sugarcane stillage, or vinasse, is the most voluminous byproduct generated in ethanol production, with an average volume ratio of 12:1. Fertigation is the simplest worldwide destination for stillage, but stricter environmental regulations require its distribution over wider areas to avoid soil oversaturation, demanding thus expensive transportation infrastructure. While reducing disposed stillage is critical, current concentration systems are inefficient and require additional energy (steam) and dedicated evaporators, which are prohibitively expensive for most installed industries. This study demonstrates, through performance comparisons with conventional distillation systems (CS), that a novel system, here denoted as HIDiE (Heat-Integrated Distillation and Evaporation), efficiently reduces the volume of stillage still during the stripping step, requiring no additional equipment and resulting in a leaner and cheaper approach. Process simulations in ASPEN Plus V11 software were used to validate premises using thermodynamic analysis and mass and energy balances. HIDiE produces significantly less stillage (1.7 - 7.8 m³/ m³_ethanol) than CS (5.4 - 14.5 m³/ m³_ethanol) under same steam consumption. Using HIDiE for wine with alcoholic grades ranging from 6 to 14 %v/v can result in gains of 45.7–69.3 %. This novel process concept contributes to the expansion of the economic radius for stillage fertigation, implying significant savings for the industry and the environment.