SRU Analyzer Best Practices
Proven field practices for tail gas analyzers in Sulfur Recovery Units (SRU). Focus: sample system temperature control, contamination prevention, calibration discipline, and using trends to detect early issues.
1) Sample System (Most SRU Issues Start Here)
- Keep temperature above sulfur dew point across probe, line, filter, and analyzer inlet.
- Eliminate cold spots (poor insulation, exposed fittings, unheated valves, metal junctions).
- Minimize dead volume to improve response time and prevent sulfur deposition pockets.
- Use corrosion-resistant materials suitable for sulfur service (avoid incompatible elastomers).
- Confirm stable sample flow and verify no restrictions or plugging at probe/filter.
Field reality: A “good reading” can still be wrong if sulfur is condensing upstream.
Condensation causes slow drift, sticky response, and unstable calibration.
2) Calibration Strategy (Do It When the Process Is Stable)
- Use certified sulfur calibration gases and track cylinder expiry / traceability.
- Calibrate only when SRU is stable; avoid start-up or rapid load changes.
- Trend before and after calibration to confirm the analyzer returned to the same baseline behavior.
- Confirm calibration gas flow / switching valves are healthy (no leaks, no sticking).
- If calibration keeps failing: treat it as a sample system temperature / contamination alarm first.
Best habit: Keep a small log: date/time, gas used, result, and “process condition note”.
This helps you prove drift vs process upset.
3) Operations & Trending (Catch Issues Early)
- Do not ignore slow drift — it usually indicates contamination or temperature instability.
- Investigate analyzer alarms quickly; SRU analyzers “snowball” when deposits build up.
- Correlate analyzer trend with SRU process: incinerator conditions, air demand, tail gas flow changes.
- Watch for slow response as an early warning of deposition/restriction.
- After maintenance: leak test + confirm heat trace works end-to-end.
Reminder: In SRU service, analyzer problems are usually sample-system related,
not electronics failures.
4) Quick Checklist (Use During Night Shifts)
Temperature
Probe + line + filter + analyzer inlet all hot & stable (no cold fittings).
Flow
Stable sample flow, no plugging, no sudden DP rise, no hunting pressure.
Leaks
No leaks at fittings/regulators; calibration gas switching OK.
Trend
Compare with last stable period; check response time and drift.