Flare Network Analysis
A flare network analysis evaluates the entire flare disposal system to ensure the flare header, sub-headers, knockout drum, piping, and flare tip can safely handle the combined relieving loads from multiple PSVs, control valves, and blowdown valves — especially during simultaneous emergency events.
Unlike relief valve sizing (which is usually single device, worst case basis), flare analysis considers system-wide interaction.
Objectives:
When is Flare Network Study Needed?
Even small changes can cause major flare issues, such as sudden backpressure increase, requiring revalidation every time load is added.
Key Checks Performed
| Parameter | What is checked | Why it matters |
|---|---|---|
| Header Hydraulics | Pressure drop & Mach number in piping | prevents choking / reduces vibration |
| Combined Load Scenarios | Sum of relief + blowdown sources | worst-case simultaneous events |
| KO Drum Sizing | Liquid hold-up, disengagement | avoid liquid carryover to flare stack |
| Flare Tip Performance | Burn efficiency, radiation | ensures environmental & personnel safety |
| Backpressure Allowable | Ensure relief valves operate correctly | Excessive backpressure can reduce PSV capacity |
Usually, tools like Aspen Flare System Analyzer or HYSYS Dynamics are used for this.
Frequently Asked Questions (FAQ)
1. What is the difference between relief sizing and flare studies?
Relief sizing focuses on individual PSV sizing for worst-case scenarios. Flare studies analyze the entire flare network to ensure the flare header, knockout drum, and stack can handle the combined relief loads.
2. Are two-phase flows handled differently?
Yes. Two-phase relief requires special correlations (Omega method, DIERS method). Standard vapor equations are not valid.
3. Do you perform studies for reactive systems?
Yes. For highly exothermic chemistries (e.g. organics, batteries, peroxides), we use ARC/DSC kinetic data and DIERS methodology.