📋 Case Study
FCC Regenerator Thermal Runaway Mitigation
Unstable regenerator temperature excursions (>730°C) causing catalyst sintering and CO spikes
🏗️ Project Overview
Refinery in Texas upgrading fluid catalytic cracking unit after catalyst change
🎯 Challenge
Unstable regenerator temperature excursions (>730°C) causing catalyst sintering and CO spikes
🔧 Design Approach
Dynamic kinetic model coupling coke combustion rate, heat release, and flue gas residence time; installed distributed thermocouples and O₂ trim control
📐 Design Diagram
AI-generated project design illustration
📐 Key Calculations
Coke Combustion Rate
r_coke = k * X_coke * P_O2^n
Result: 0.82 g coke/g cat·min
Validated via TGA and microreactor data
Adiabatic Flame Temperature (T_ad)
T_ad = T_in + (−ΔH_coke * X_coke) / (Σ Cp_i * y_i)
Result: 825°C
Explained observed peak temperatures
CO Oxidation Delay Time
τ_CO = 1/k_CO * ln(CO_in/CO_out)
Result: 12.7 s
Confirmed insufficient residence time for complete CO burnout
📊 Results
Regenerator outlet temp stabilized at 705±3°C, CO emissions reduced by 92%, catalyst life extended by 35%💡 Lessons Learned
- •Coke oxidation kinetics are strongly inhibited by steam—ignored in legacy models
- •Thermocouple placement depth affects measured lag and false-positive runaway alarms
- •Dynamic model must include catalyst inventory heat capacity as state variable
✅ Key Takeaways
- 1Coke oxidation kinetics are strongly inhibited by steam—ignored in legacy models
- 2Thermocouple placement depth affects measured lag and false-positive runaway alarms
- 3Dynamic model must include catalyst inventory heat capacity as state variable