Maintain Compliance to Petrochemical (EMACT) and Organic Chemical Sector (MON) Flare Gas Rules with Rapid Online Analysis by Prima PRO Mass Spectrometers

Importance of the topic

Government regulators increasingly require continuous, accurate monitoring of flare and vent gases at refineries, petrochemical plants and organic chemical manufacturers to limit hazardous air pollutant emissions and to demonstrate compliance with recent EPA rules (EMACT, MON and the Refinery Sector Rule). Fast multicomponent analysis of flare streams is essential because compositions change rapidly, combustion performance depends on aggregate fuel properties (e.g., net heating value), and regulatory limits (for example a combustion-zone net heating value minimum of 270 BTU/scf) must be met with minimal delay.

Objectives and overview of the application note

The application note describes how the Thermo Scientific Prima PRO Process Mass Spectrometer, paired with the Rapid Multistream Sampler (RMS) and GasWorks software, provides rapid online compositional analysis and derived fuel properties for flare and process gas streams. It documents analytical performance, speed, multistream capability, sulfur-speciation performance and the role of derived values (LHV, HHV, NHV, Wobbe indices, density, air requirement) in meeting EMACT, MON and RSR regulatory requirements.

Methodology

The approach uses magnetic-sector process mass spectrometry with an enclosed high-energy (1000 eV) ion source and a variable magnetic field to resolve mass-to-charge ratios. GasWorks software manages analysis methods, derives fuel properties from measured component concentrations and provides multiple plant interfaces (4–20 mA/0–10 V, Modbus, Profibus, OPC). Typical analysis cycles, including stream switching, are under 30 seconds. Multi-stream selection is performed by the RMS (1-of-32 or 1-of-64), which is heated to 120°C, optically encoded and capable of long maintenance intervals.

Used instrumentation

• Thermo Scientific Prima PRO Process Mass Spectrometer — magnetic sector analyzer with enclosed 1000 eV ion source.
• Rapid Multistream Sampler (RMS) — heated (to 120°C) stream selector, up to 64 streams, digital flow recording and >10 million operations MTBM.
• GasWorks software — method management, Derived Values (LHV, HHV, NHV, Wobbe indices, density, CARI) and host communication.
• Thermo Scientific SOLA iQ Flare System (PUVF) — recommended complementary analyzer for true continuous total sulfur (converts organo-sulfur to SO2 and measures fluorescence).

Main results and discussion

The Prima PRO MS demonstrates rapid, precise multicomponent analysis suitable for flare monitoring: typical measurement times are ≤30 seconds including stream switching. Magnetic-sector performance provides 2–10× better precision than typical quadrupole instruments for many gases and significantly improved resistance to contamination and calibration drift. The enclosed high-energy ion source supports stable operation on high-percent organics.

Key factory-test data (gravimetric cylinder with 21 components, analyzed over 8–18 hours):

• Component precision (single standard deviation over 8 h) met or exceeded Prima PRO specifications — e.g., Hydrogen (10 %mol) spec ≤0.02 %mol, measured average 9.8835 %mol, sd 0.0077; Methane (64.53 %mol) sd 0.0125; H2S (0.05 %mol) sd 0.0003.
• Derived NHV during the test: 899.5394 BTU/scf with a relative standard deviation of 0.07% over the measurement period, demonstrating excellent stability for regulatory compliance calculations.
• Sulfur linearity tests: units calibrated at single concentrations (H2S at 0.0506%mol, COS at 0.2006%mol, CS2 at 0.198%mol) showed linear responses across wide ranges — H2S measured from trace up to ~90%mol, demonstrating large dynamic range and linearity for sulfur species.

The magnetic-sector analyzer produces flat-topped peaks (focused ion beam), enabling high-precision measurements wherever within the peak top the sampling occurs. GasWorks-derived fuel properties use EPA-recommended practical values (e.g., hydrogen LHV = 1212 BTU/scf per EPA 40 CFR Parts 60 and 63) to calculate operational metrics relevant to flare combustion efficiency.

Limitations and cautions:

• Mass spectrometry reports total sulfur only as the sum of identified sulfur species; unknown or undetected sulfur compounds are not included. For regulatory-grade total sulfur, a dedicated total-sulfur analyzer (e.g., SOLA iQ PUVF) is recommended.
• Spectral overlap in MS fragmentation requires calibration with actual components where possible; surrogate calibrations can simplify setup but reduce accuracy.

Benefits and practical applications

The Prima PRO solution offers multiple practical benefits for operations and compliance:

• Fast detection and reporting (<30 s) reduce the risk of non-compliance by enabling rapid corrective actions (e.g., adding fuel gas or steam when NHVCZ approaches limits).
• High precision and stability reduce the frequency of recalibration and improve confidence in derived fuel properties used for control decisions.
• Multistream capability (RMS) allows one analyzer to monitor several flare and process streams for root-cause analysis and to correlate process upset sources with flare composition.
• Flexible outputs and integration enable alarm triggers, supervisory control integration and continuous regulatory reporting.

Future trends and opportunities

Anticipated directions and applications include:

• Tighter integration of MS compositional data with continuous total sulfur detectors to provide both speciated and true total-sulfur readings for compliance.
• Advanced data analytics and pattern recognition (including machine learning) to detect anomalous source signatures, predict flare performance excursions and recommend corrective actions.
• Expanded multistream remote monitoring architectures that centralize flare and process surveillance across large plants.
• Further regulatory harmonization and wider adoption of continuous multicomponent monitoring as EMACT/MON/RSR-style rules spread internationally.

Conclusion

The Prima PRO Process Mass Spectrometer, combined with the RMS sampler and GasWorks software, provides a robust, rapid and precise platform for continuous flare and process gas monitoring. Magnetic-sector MS delivers superior precision, dynamic range and contamination resistance compared with many quadrupole alternatives. Measured performance in factory tests demonstrates suitability for regulatory compliance tasks (e.g., NHV/NHVCZ calculations, sulfur-speciation) while highlighting the need to pair MS with a true total-sulfur analyzer when an absolute total-sulfur value is required.

References

1. US Environmental Protection Agency. 40 CFR § 63.670 – Requirements for Flare Control Devices.
2. Thermo Fisher Scientific. Continuous flare stack emission monitoring: Thermo Scientific SOLA iQ Flare Analyzer. Application Note, 2020.
3. Thermo Fisher Scientific. Advancing Process Control and Efficiency During Ethylene Production Using the Thermo Scientific Prima PRO Process Mass Spectrometer. Application Note, 2014.
4. Thermo Fisher Scientific. Thermo Scientific Prima PRO Process Mass Spectrometer: Improving ethylene oxide process control. Application Note, 2017.