📋 Case Study

Bioethanol Distillation Energy Integration at Brazilian Sugarcane Mill

Steam demand exceeded boiler capacity during peak season; column flooding observed

🏗️ Project Overview

350 m³/day anhydrous ethanol plant in São Paulo

🎯 Challenge

Steam demand exceeded boiler capacity during peak season; column flooding observed

🔧 Design Approach

Heat integration via vapor recompression + column sequencing optimization using Aspen Custom Modeler

📐 Design Diagram

Boiler Cap: 12.4 t/h Prefrac Main Col Stripper VR COP = 2.9 Reb Flooding Steam deficit Rmin = 1.62 Δh/W = 2.9 Bioethanol Distillation Energy Integration

AI-generated project design illustration

📐 Key Calculations

Vapor Recompression COP

Δh_comp / W_comp
Result: 2.9
Measure of energy recovery efficiency

Minimum Reflux Ratio (Underwood)

R_min = (xD − α·xB)/(α − 1) × (1 − xB)/(xD − xB)
Result: 1.62
Sets theoretical energy floor

📊 Results

58% steam reduction, 100% elimination of column flooding, 27% lower specific energy (MJ/L ethanol)

💡 Lessons Learned

  • Non-ideal VLE (NRTL) required to predict azeotrope shift with water-ethanol-impurities
  • Dynamic simulation revealed startup transients causing temporary overloads

Key Takeaways

  • 1Non-ideal VLE (NRTL) required to predict azeotrope shift with water-ethanol-impurities
  • 2Dynamic simulation revealed startup transients causing temporary overloads