Featured Project: Emergency Sour Naphtha Tank Degassing – Northern California Refinery (BAAQMD & API 653 Compliance)
In mid-April 2016, a Northern California refinery discovered a seal leak on a 145 ft. diameter x 75 ft. tall above-ground external floating roof storage tank in sour naphtha service. The sour nature of the product posed substantial safety and environmental hazards, including H2S exposure (>600 ppm) and pyrophoric iron sulfide risks upon oxygen introduction, violating BAAQMD Regulation 8, Rule 2: Sulfur Compounds limits for refinery H2S emissions (e.g., <10 ppm ground-level) and API 653 safe entry standards for sour service tanks. Envent’s rapid deployment of a permitted H2S scrubber and thermal oxidizer mitigated these risks while accelerating degassing.
The Challenge: Sour Seal Leak on Massive EFRT Tank
The leak released H2S-laden vapors near community receptors, risking BAAQMD Rule 402 nuisance violations and worker exposure (OSHA PEL 10 ppm). Pyrophoric hazards required <12% O2 inerting per EPA BACT for H2S in refineries, complicating degassing for API 653 inspection.
Key Risks:
- H2S concentrations ~600 ppm at scrubber inlet
- Pyrophoric ignition on O2 exposure (iron sulfide in sour naphtha)
- Regulatory scrutiny under BAAQMD refinery emissions guidelines
- Schedule delays costing $6,000+/day
Envent’s Rapid Solution: Permitted H2S Scrubber + EMTOS-2000
Envent responded within hours, deploying a BAAQMD-permitted dual-column packed bed recirculating H2S scrubber and EMTOS-2000 thermal oxidizer, with simultaneous N2 inerting for <12% O2.
Treatment Process:
- H2S Scrubbing: Dual-column recirculating wet scrubber (caustic media) reduced inlet ~600 ppm H2S to 0 ppm at EMTOS inlet, per EPA BACT for gaseous scrubbers.
- Thermal Oxidation: EMTOS-2000 destroyed residual VOCs/H2S at >1,500°F (>99.9% DRE), converting to CO2/SO2 with real-time monitoring.
- Pyrophoric Mitigation: N2 flow maintained <12% O2, preventing ignition per API 653 sour service guidelines and BAAQMD refinery fugitive emissions.
- Bypass Optimization: Once H2S <0 ppm, bypassed scrubber for higher flow, accelerating degassing.
System ran 24/7 with Envent operators. For sour tank applications, explore Envent’s H2S scrubber rentals.
Official Resources:
- BAAQMD Regulation 8, Rule 2: Sulfur Compounds – H2S limits for refinery vents.
- EPA BACT for Scrubbers in Refineries – >99% H2S removal standards.
- API 653 Tank Inspection Standards – Sour service entry protocols.
Proven Benefits: 5 Days Faster, $30K Saved, Zero Hazards
Envent’s solution protected workers and community while accelerating the project:
| Benefit | Project Impact |
|---|---|
| Speed | Finished 5 days early via scrubber bypass for higher flow. |
| Safety | <12% O2 inerting eliminated pyrophoric risks; zero incidents. |
| Emissions Control | H2S from ~600 ppm to 0 ppm; >99.9% DRE, no odors or releases. |
| Cost Savings | ~$30,000 from accelerated schedule vs. standard methods. |
| Compliance | 100% BAAQMD Reg 8-2 & API 653 compliant; protected community from H2S. |
This 2016 project underscores Envent’s expertise in sour tank degassing, where rapid H2S mitigation drives safety and efficiency.
Facing a Sour Tank Leak or Degassing Emergency? Get a Free BAAQMD H2S Review & Quote Contact Envent’s engineers at 888-997-9465 or email [email protected] for a no-obligation assessment. We’re California-ready—explore our thermal oxidizers.
