📋 Case Study

Polymer Reactor Runaway Reaction Mitigation via SIS Redundancy Upgrade

Single-point failure in temperature trip logic led to near-miss runaway event

🏗️ Project Overview

High-pressure propylene polymerization reactor experiencing thermal excursions

🎯 Challenge

Single-point failure in temperature trip logic led to near-miss runaway event

🔧 Design Approach

IEC 61511-compliant SIL 3 redesign: dual redundant RTDs + voting logic + independent logic solver; added pressure-based backup trip

📐 Design Diagram

_avg = 0.00072 → SIL 3 Compliant RTD Sensor Pressure Transmitter Trip Output

AI-generated project design illustration

📐 Key Calculations

PFDavg Calculation

PFDavg = λDU × T / 2 + λDD × β

Result: PFDavg = 0.00072 → SIL 3 compliant

Validated fault tolerance and diagnostic coverage

📊 Results

Zero thermal excursions in 28 months; 100% uptime maintained during catalyst changeovers; passed CCPS RBPS audit with zero findings

💡 Lessons Learned

• •Redundancy without diversity increases common cause failure risk
• •Logic solver independence must include physical separation and power isolation

✅ Key Takeaways

• 1Redundancy without diversity increases common cause failure risk
• 2Logic solver independence must include physical separation and power isolation