Flare Stack Emission Monitoring

Fast online monitoring of flare gases

Flare stacks emit excess hydrocarbon gases that cannot be recovered or recycled. These gases combined with steam and/or air are burnt off in the flare system to produce water vapor and carbon dioxide. Increasingly, national and local government bodies are requiring processing companies to monitor the various emissions from their plant stacks and flares to reduce the amount of pollution entering the atmosphere.

The US Environmental Protection Agency (EPA) has published amendments to Refinery Sector Rule RSR) 40 CFR Part 63 affecting flares; refineries must bring flares into compliance with new §63.670 ‘Requirements for Flare Control Devices’.

The new requirements define five flare operating limits:

  1. combustion zone net heating value (NHVCZ)
  2. dilution net heating value (NHVdil)
  3. flare tip exit velocity
  4. pilot flame presence
  5. visible emissions that specifies an NHVCZ minimum operating limit of 270 BTU/scf, based on a 15 minute block period.

NHVCZ can be calculated by measuring the net heating value of the vent gas (NHVVG), making flare gas analysis a vital part of any compliance strategy. If the NHVCZ approaches 270 BTU/scf, additional fuel gas such as propane or natural gas must be added. This may then require the addition of steam to the flare, to avoid the production of visible emissions. The analysis of flare gases presents a series of challenges to the processing industries.


Featured flare stack emission monitoring analyzers

Measurement of flare gas streams by process mass spectrometry:

The Thermo Scientific Prima PRO Process Mass Spectrometer  is the world’s leading process mass spectrometer, designed to operate reliably in harsh production environments. Process Mass Spectrometry is particularly suited to the measurement of flare gas streams because it offers accurate, fast, multicomponent analysis.

  • Scanning magnetic sector technology for fast, flexible, precise multi-component analysis. Concentrations of the full composition of the flare gas stream are reported in seconds.
  • 32- or 64-port Rapid Multistream Sampler (RMS) for fast, reliable monitoring of multiple sample points from Flare or Process streams.
  • Performance independently evaluated by the world-renowned test laboratory Effectech UK.
  • Magnetic Sector technology is resistant to contamination and operates for several months between fully automated calibration.

Total sulfur analysis of flare gas streams:

Utilizing unique Pulsed Ultraviolet Fluorescence (PUVF) technology and the proven Pyrolysis system, the Thermo Scientific SOLA iQ Flare Analyzer builds on the success of the SOLA II flare analyzer.

  • Two fully independent calibration ranges enable total sulfur measurement from ppm to 100% concentration.
  • Automatic range switching to ensure continuous measurement during flaring events.
  • Low cost of ownership, using only air for combustion.
  • Intuitive color touchscreen user interface with comprehensive online diagnostics and extensive user configurable I/O.

Flare Gas Monitoring with the Prima PRO Process Mass Spectrometer

The Prima PRO Process Mass Spectrometer offers fast, accurate, and multicomponent analysis for plant stack.