Featured Project: Flareless Hydrocracker Turnaround under EPA Refinery Sector Rule (40 CFR 63 Subpart UUU)
The EPA’s 2020 Refinery Sector Rule (RSR) amendments to 40 CFR Part 63 Subpart UUU (Refinery MACT 2) imposed the strictest flare limits in history:
- Work Practice Standards now prohibit >500 ppmv H₂S on flare assist gas during normal operation
- Flare tip velocity, NHVcz, and combustion zone monitoring during MSS events
- Depressuring events >2 psig must route to a control device with ≥98% destruction efficiency
This refinery’s existing flare could no longer accept the full volume of hydrocracker depressuring vapors — especially the initial 99% hydrogen stream — without violating the new RSR limits.
The Challenge
- Safely depressure a 60,000 bpd hydrocracker containing 99% hydrogen + residual H₂S
- Multiple nitrogen purges required before maintenance entry
- No flare capacity available under RSR work practice standards
- Zero tolerance for atmospheric release or safety incidents
- Must meet original turnaround schedule
Envent’s Zero-Flare Turnaround Solution
Envent mobilized the largest mobile destruction fleet ever deployed for a single unit:
| Equipment | Quantity | Purpose |
|---|---|---|
| EMECS-42 (42 MMBTU/hr) | 3 | >99.9% destruction of hydrogen & VOCs |
| ESCRUB-6000 Recirculating Scrubber | 2 | >99% H₂S removal post-nitrogen purge |
| VFD Supplemental Blower | 1 | Maintained flare header <27″ WC |
| Full safety & monitoring package | — | LEL, H₂S, pressure, flow, remote telemetry |
Execution Highlights
- Initial hydrogen-rich depressuring routed directly to three parallel EMECS-42 units
- Post-hydrogen nitrogen purges scrubbed of H₂S via dual ESCRUB-6000 units
- VFD blower kept refinery flare header under vacuum — preventing any backflow
- 24/7 Envent operators + real-time data shared with refinery control room
- All operations documented for EPA RSR compliance reporting
Result: Zero flare usage, zero atmospheric emissions, zero safety incidents — and the hydrocracker was turned over to maintenance on schedule.
Proven Benefits – RSR Compliance Without Delay
| Benefit | Delivered Outcome |
|---|---|
| EPA RSR Compliance | 100% of vapors destroyed — no flare tip violations |
| Safety Record | Zero incidents during 99% hydrogen handling |
| Turnaround Schedule | Met original dates — no delay despite flare limits |
| Flare Header Protection | <27″ WC maintained throughout |
| Documentation | Full dataset for EPA 63.670(o) work practice reporting |
This remains the benchmark for flareless hydrocracker, FCCU, and coker turnarounds nationwide under the Refinery Sector Rule.
Planning Your Next RSR-Compliant Flareless Turnaround? Get your Free EPA Refinery MACT 2 Compliance Review & Quote today. Call Envent’s Turnaround Division at 888-997-9465 or email [email protected] — the only company with proven zero-flare hydrocracker experience.
