Fatigue, Ratcheting & Hot Box Analysis of C2 Hydrogenation Reactor
FEA Case Study | ASME Section VIII Division 2 Compliance
1. The Engineering Challenge
Parallel C2 Hydrogenation Reactors operate under extreme conditions in ethylene plants, converting acetylene to ethylene through catalytic reaction. The reactor experiences:
- Dual temperature regimes: 320°C normal operation, 535°C regeneration
- Cyclic thermal loading: Startup → Operation → Regeneration → Shutdown
- Combined pressure + thermal stresses: 26 kg/cm² internal pressure
- Hot box thermal gradients: Extreme temperature differential zones
2. Project Overview
Figure 1: R-1097 Hydrogenation Reactor 3D Model
3. FEA Model Quality
Figure 2: Structured mesh at nozzle-shell intersections
6. Results Preview
Figure 3: Von Mises stress at top head – LC1 (Max: 212.97 MPa)
Figure 4: Hot box stress under operating condition (Max: 178.36 MPa)
Figure 5: Max stress at Skirt Junction (Critical fatigue location)
Key Takeaways for Engineers
- High-temperature vessels require fatigue and ratcheting assessment, not just static stress checks
- ASME VIII-2 Part 5 provides the framework, but proper FEA implementation is critical
- Temperature-dependent material properties are essential, using room-temperature values leads to non-conservative results
- The “worst” load case isn’t always obvious, systematic evaluation of all combinations is necessary
Download the Full Technical Case Study
The complete engineering report includes:
- Stress results for all 10 load cases
- Fatigue damage calculation per ASME VIII-2 5.5.3
- Ratcheting assessment per ASME VIII-2 5.5.6
- Hot box thermal gradient analysis
- SCL linearization at all maximum stress locations