Featured Project: Sulfur Recovery Unit Odor Backup Control in Texas Refinery – TCEQ Ch. 112 & EPA BACT Compliance (Case Study)
In Texas refineries, 30 TAC Chapter 112: Control of Air Pollution from Sulfur Compounds regulates H2S emissions from sulfur recovery units (SRUs), with §112.8 limiting ground-level concentrations to 10 ppm (30-min avg) and requiring Best Available Control Technology (BACT) for odor nuisances (§112.1 definitions), including wet scrubbing or carbon adsorption for vents exceeding 100 lbs/hr H2S. Particulate clogging in SRU tail gas treaters (TGTUs) can spike H2S >1,000 ppm, triggering episodic release reporting under 30 TAC §101.201 and fines up to $100,000/day for non-compliance with NSPS Subpart J (40 CFR 60). EPA’s BACT Guidelines for H2S Control in Refineries endorse wet scrubbing (>99% removal) and activated carbon (>95% H2S adsorption) as primary options for SRU backups, preventing corrosion and community complaints. Envent’s VapoScrub H2S5 excels here, offering passive, clog-resistant chemistry for sustained performance.
The Challenge: SRU Odor System Overload from Particulate Clogging
A Texas refinery’s sulfur recovery unit (SRU)—processing acid gas from hydrotreaters to recover >95% sulfur per NSPS J—experienced odor breakthrough when particulates (e.g., catalyst fines, sulfur mist) clogged the existing caustic scrubber, spiking H2S emissions >500 ppm and causing off-site complaints. Backup was needed to maintain §112.8 limits without halting operations.
Key Risks:
- Odor & Emission Hazards: H2S >10 ppm ground-level risks NOVs under §112.2; uncontrolled vents could exceed 100 lbs/hr, triggering TGTU redesign per TCEQ SRU guidance.
- Regulatory Pressure: Refineries must report episodic H2S releases (§101.201); failures incur $10,000–$100,000/day fines, plus EPA MACT inspections for HAPs like H2S.
- Operational Downtime: Clogging forced reduced throughput, costing $50,000+/day; traditional backups risked further fouling.
Official Resources:
- TCEQ 30 TAC Chapter 112: Sulfur Compound Controls – H2S limits (§112.8) and odor rules for SRUs.
- TCEQ SRU Permitting Guidance – BACT for backups and TGTU efficiency.
- EPA Wet Scrubber BACT for H2S – >99% removal in refinery vents.
- EPA Activated Carbon BACT for H2S Odors – Specialty carbon for refinery applications.
Envent’s Multi-Option Solution: Custom VapoScrub H2S5 Passive Scrubber Selected
Envent’s engineers evaluated SRU tail gas flows (up to 1,000 scfm) and H2S loads (>1,000 ppm), proposing three TCEQ-compliant backups under minor source rules (§116.119):
- Option 1: 4,000 lbs Darco H2S Activated Carbon: High-capacity bituminous carbon (e.g., Norit Darco H2S LP) for catalytic H2S adsorption (>95% efficiency), ideal for dry vents but requiring frequent change-outs in particulate-laden streams.
- Option 2: VapoScrub H2S5 in Passive Chemical Scrubber: Envent’s proprietary non-caustic media in an ESCRUB-1000 unit—clog-resistant packed tower for >99% H2S removal via chemisorption, per VapoScrub H2S5 Data Sheet.
- Option 3: Sodium Hydroxide (Caustic) Solution: Standard wet scrubber (10–20% NaOH) for >98% H2S neutralization, but prone to salt buildup in particulate flows.
The client selected VapoScrub H2S5 for its passive operation (no pumps needed for low flows) and superior longevity. Deployed in parallel to the SRU vent, it routed gases through a heated, anti-fouling media bed, with real-time H2S sensors ensuring <5 ppm outlet. For SRU backups, explore Envent’s odor control scrubbers.
Proven Benefits: $200K Savings, Zero Odors, & Sustained Compliance
VapoScrub H2S5 outperformed alternatives, resolving the clogging crisis while aligning with TCEQ §112.8:
| Benefit | Project Impact |
|---|---|
| H2S Removal Efficiency | >99% — inlet >1,000 ppm → outlet <5 ppm, exceeding EPA BACT & §112.8 limits. |
| Clog Resistance & Life | >60 days runtime vs. carbon’s <30 days or caustic’s fouling issues—per VapoScrub specs. |
| Cost Savings | $200,000+ over project duration (fewer media swaps, no downtime vs. carbon/caustic). |
| Compliance Assurance | Zero odors/NOVs; full records for TCEQ SRU audits (§112.9 monitoring). |
| Operational Edge | Passive design maintained SRU throughput; no particulate carryover to downstream. |
This Texas SRU project exemplifies Envent’s innovation in TCEQ Chapter 112 H2S odor controls, where VapoScrub prevents costly breakthroughs.
Need SRU Odor Backup? Get a Free TCEQ Ch. 112 Review & Quote Contact Envent’s engineers at 888-997-9465 or email [email protected] for a no-obligation assessment. We’re Texas refinery experts—explore VapoScrub solutions.
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