Executive Summary
When a major Louisiana terminal needed to degas a 123-foot diameter naphtha tank without halting operations, they faced a critical challenge. Specifically, they had to adhere to strict LDEQ air permit revisions and EPA Subpart OOOOb standards.
The facility required a solution that could safely handle high-volatility vapors (RVP >4 psia). At the same time, it had to maintain a minimal physical footprint to avoid relocating critical piping. Envent mobilized the EMTOS-3500 Mobile Thermal Oxidizer within one hour.
Result: >99.4% VOC destruction, zero Title V deviations, and $150,000+ saved in labor and logistics.
Project At A Glance
- Location: Louisiana Gulf Coast
- Challenge: High-VOC Naphtha Tank Degassing (123-ft dia.)
- Solution: EMTOS-3500 Mobile Thermal Oxidizer
- Outcome: <5 tpy VOCs (Insignificant Activity Status) & Zero Downtime
The Challenge: Large-Scale Naphtha Tank Degassing with Minimal Site Disruption
A Louisiana tank farm operator needed to de-inventory and degas a massive 123-foot diameter naphtha storage tank. This tank held highly volatile petroleum distillate with a Reid Vapor Pressure (RVP) >4 psia. Consequently, it generated substantial VOC emissions during roof landing, cleaning, and vapor displacement.
Key Constraints Regulatory Compliance Under LDEQ’s Air Permitting Rules (LAC 33:III.501), degassing tanks >40,000 gallons requires pre-notification for minor source permits if potential emissions exceed 5 tpy of any criteria pollutant or the Minimum Emission Rate (MER) for toxic air pollutants (TAPs) like benzene in naphtha. As a result, uncontrolled releases could trigger PSD/NSR reviews or fines up to $32,500/day under La. R.S. 30:2050.3 — especially after 2025 Subpart OOOOb updates for methane/VOC co-controls.
Operational Demands The site required a compact, low-disruption system. Relocating critical piping, pumps, or adjacent tanks was not feasible, as it was essential to maintain throughput in this busy Gulf Coast facility.
Emission Risks Naphtha degassing could release 500+ lbs of VOCs (e.g., BTEX compounds) per event. Therefore, >95% destruction efficiency was necessary to qualify for insignificant activity status under LAC 33:III.501.B.5, Table D.
Official LDEQ Resources
- Air Permits & Minor Source Applications – Guidance for VOC tank degassing notifications and exemptions.
- Case-By-Case Insignificant Activities – Exemption criteria for low-emission degassing events.
Envent’s Compact Solution: EMTOS-3500 Mobile Thermal Oxidizer Deployment
Envent secured a minor source permit via LDEQ’s expedited process and mobilized the EMTOS-3500 Envent Mobile Thermal Oxidizer within one hour. This trailered unit is specifically designed for petrochemical degassing and features a minimal 8′ x 25′ footprint for easy staging near tank vents.
Treatment Process & VOC Destruction Details Vapor Capture & Routing Vapors (up to 3,500 scfm from the 123-ft tank) were ducted directly from the tank’s conservation vent and roof drains to the EMTOS-3500 via temporary, low-profile piping. This approach avoided site-wide disruptions.
Thermal Oxidation Efficiency The combustion chamber preheated vapors to 1,500°F+. As a result, naphtha VOCs underwent >99.428% destruction (verified via EPA Method 25A stack testing). Pollutants were converted to CO₂ and water, exceeding LDEQ’s BACT requirements under LAC 33:III.517 for synthetic minor sources. Auxiliary fuel (natural gas) was limited to <10% of total heat input, minimizing NOx byproducts per 2025 Subpart OOOOb guidelines.
Compliance Integration Real-time monitoring of temperature, flow, and heat content ensured full adherence to permit conditions. Post-job emissions calculations (using TANKS software per AP-42) confirmed <5 tpy VOCs — qualifying for insignificant activity exemption without further reporting. Flame arrestors and auto-ignition prevented flashbacks in the naphtha-rich stream.
The system ran continuously through de-inventory, enabling safe entry for cleaning. For naphtha-specific applications, check Envent’s EMTOS thermal oxidizer rentals.
Proven Benefits: Operational Continuity, Cost Savings, and LDEQ Compliance
| Benefit | Project Impact |
|---|---|
| Footprint & Disruption Savings | 8′ x 25′ staging allowed 100% site operations to continue—no equipment relocations, saving $150,000+ in labor and logistics vs. larger flare systems. |
| VOC Emission Reductions | >99.428% destruction prevented 1,000+ lbs of uncontrolled naphtha VOCs, aligning with LDEQ’s <5 tpy threshold for exemption and avoiding NSR triggers. |
| Regulatory Assurance | Pre-permitted deployment ensured zero Title V deviations; full records supported LDEQ’s 2025 OOOOb methane co-reporting without audits. |
| Timeline Efficiency | One-hour mobilization accelerated degassing by 2 days, reducing overall turnaround costs by 20%. |
| Safety & Scalability | Compact design lowered LEL risks in confined spaces; scalable for future events under updated LAC 33:III.2103 requirements for high-RVP tanks. |
This Louisiana success cements Envent’s role in LDEQ-compliant tank degassing, where compact VOC controls drive 2025 efficiencies.
Planning Your Louisiana Tank Degassing? Get a Free LDEQ Permit Review & Quote today. Call Envent’s engineers at 888-997-9465 or Request a Quote. We’re Gulf Coast-ready — discover our mobile thermal oxidizers.
