H2S Scrubber + Thermal Oxidizer: How Envent Safely Handled 500,000 ppm Sour Water in a 2025 Washington Turnaround
When a Puget Sound refinery kicked off a major 2025 turnaround, one tank immediately became the biggest headache: a sour water stripper tank loaded with 500,000 ppm (50%) H₂S. An efficient H2S Scrubber was vital to handle this challenge.
To make matters worse, hundreds of workers were only feet away, temperatures were dropping below 20 °F, and Washington’s strict 2025 air rules left zero room for error.
Fortunately, Envent responded in hours with the perfect combination: a **heated H₂S scrubber (ESCRUB-1000) followed by a high-capacity thermal oxidizer (EMTOS-3500). The result? Zero odors, zero safety evacuations, zero PSCAA complaints — and the turnaround stayed on schedule.
Project At A Glance – H2S Scrubber Success
- Location: Puget Sound Refinery, Washington
- Challenge: 500,000 ppm H₂S sour water tank during full plant turnaround
- Solution:Heated H2S Scrubber ESCRUB-1000 + EMTOS-3500 Thermal Oxidizer (video)
- Outcome: >99% H₂S removal, >99.9% destruction, full PSCAA Reg II BACT compliance in freezing weather
Why This H2S Scrubber Project Was Extremely High-Risk
First, H₂S levels were 25,000 times higher than OSHA’s 20 ppm limit — deadly within minutes above 700 ppm. Next, the tank sat in the middle of an active work zone with welders and scaffolders everywhere. Then came the weather: Puget Sound winter nights dropped to 20 °F, which normally freezes caustic in standard scrubbers and shuts projects down. Finally, 2025 regulations were unforgiving:
- PSCAA Regulation II – Toxic Air Pollutants & BACT
- Washington Refinery GHG Rules (WAC 173-415)
- EPA Refinery MACT / NESHAP Subpart CC
Any uncontrolled release would trigger immediate reporting and fines up to $100,000 per day.
How Envent’s H2S Scrubber + Thermal Oxidizer System Worked Perfectly
Because every minute mattered, Envent secured the PSCAA Notice of Construction (NOC) permit fast and mobilized within hours. Here’s exactly how the system performed:
| Step | Equipment & Technology | Real-World Performance |
|---|---|---|
| Primary H₂S Knockdown | Heated H2S Scrubber – ESCRUB-1000 | Dropped 500,000 ppm → <1,000 ppm (>99% removal) |
| Winter-Proof Design | Electric heat tracing + antifreeze + insulated tanks | Zero freeze-ups even at 20 °F |
| Final Destruction | EMTOS-3500 Mobile Thermal Oxidizer | >99.9% destruction of residual H₂S, VOCs & odors |
| Proof of Compliance | Real-time H₂S analyzers + EPA Method 15 stack testing | Instant documentation for PSCAA & refinery records |
Thanks to heated lines, hot caustic recirculation, and 24/7 monitoring, the H₂S scrubber and thermal oxidizer ran flawlessly from the first purge to the final sweep — even during the coldest nights.
Results That Speak for Themselves
| Benefit | What Actually Happened |
|---|---|
| H₂S & Odor Control | 100% odor-free – zero community or PSCAA complaints |
| Safety | Ambient H₂S stayed <10 ppm – full crew access, no evacuations |
| Regulatory Compliance | Met every PSCAA Reg II BACT and EPA MACT requirement |
| Cold-Weather Reliability | Saved 3+ days vs. traditional systems that would have frozen |
| Cost Avoidance | Prevented $150,000+ in turnaround delays |
This remains one of the most successful H₂S scrubber + thermal oxidizer projects ever completed under Washington’s toughest 2025 air regulations.
Need an H2S Scrubber or Thermal Oxidizer for Your Next Washington Turnaround?
Don’t let sour water tanks derail your schedule or trigger PSCAA enforcement.
Get Your Free PSCAA-Compliant H₂S Control Plan & Quote Today Call Envent’s Pacific Northwest Team 24/7 at 888-997-9465 or Request Quote – H2S Scrubber & Thermal Oxidizer →
We’re pre-permitted across Washington and keep heated H₂S scrubbers and thermal oxidizers ready to roll — we mobilize in hours, not days.
