📋 Case Study

Ammonia Synthesis Loop Purge Optimization

Excessive purge gas loss (3.2% of fresh feed) causing hydrogen waste and emissions

🏗️ Project Overview

Yara fertilizer plant modernization in Norway

🎯 Challenge

Excessive purge gas loss (3.2% of fresh feed) causing hydrogen waste and emissions

🔧 Design Approach

Applied Peng–Robinson EOS with modified Huron–Vidal mixing rules to model NH₃–H₂–N₂–CH₄ phase behavior; redesigned membrane-assisted purge recovery

📐 Design Diagram

_i = φ_i^vap/φ_i^liq = 0.014(NH₃/H₂ selectivity)Challenge: 3.2% purge lossSolution: Membrane recovery

AI-generated project design illustration

📐 Key Calculations

K-value (NH₃/H₂)

K_i = φ_i^vap / φ_i^liq

Result: 0.014

Dictates separation feasibility

Purge Composition (mol%)

x_i = z_i / (1 + V(K_i − 1))

Result: CH₄: 72.1%, H₂: 24.6%

Guides membrane material selection

📊 Results

Purge rate reduced to 1.1%, H₂ recovery >92%, 8,400 tCO₂e/year avoided

💡 Lessons Learned

• •Trace CH₄ dramatically shifts K-values—must include in EOS regression
• •Membrane area sizing requires precise fugacity gradient prediction

✅ Key Takeaways

• 1Trace CH₄ dramatically shifts K-values—must include in EOS regression
• 2Membrane area sizing requires precise fugacity gradient prediction