James G. Seebold[1]

 

Today there is a desperate need for proven industrial flare emissions remote measurement and quantification.  Nobody denies that and I count myself among the foremost of the wishful thinkers.

Today’s promoters almost uniformly and seemingly very carefully refer to sensing and detection when discussing today’s available technologies.[2]  There is a very good reason for that.

Take for example the Passive Fourier Transform Infrared (PFTIR) technology that is, today, being applied to “quantify” emissions and combustion efficiencies in the US Department of Justice / US Environmental Protection Agency Enforcement Division’s Consent Decree regulatory activism.  By “regulatory activism” I refer to the regulation by enforcement strategy that has been resorted to in the realization that today’s industrial flare emissions law, the 40CFR60.18’s General Requirements for Flares, is inadequate to ensure greater than 98% combustion efficiency.

Exceedingly well-founded theoretically, PFTIR has the potential to become an excellent remote measurement and quantification technology.  Virtually everyone is rooting for it and I am one of the most enthusiastic of rooters.  But PFTIR remains unproven in blind-validation trials against well-established regulatory-agency-approved extractive sampling methods.  In fact, despite the fact that the final report spins the results very positively, in TCEQ’s well-executed “Phase I” trials PFTIR failed blind-validation.

Any who are seriously and objectively interested can read the report for themselves and extract the truth.[3]  The TCEQ Phase I tests utilized a hot gas generator whose plume was seeded with known concentrations of target compounds, concentrations that were verified by extractive sampling. PFTIR had a good oblique view of the plume.  Nevertheless, PFTIR failed blind-validation.  Considerable differences were observed between the known target compound concentrations and those obtained by remote PRTIR “measurement.”  To its credit, the report acknowledges that the differences “... are not well understood ...” but asserts that that an “... improved detector design should help improve the overall sensitivity for C₃+ and THC.”  Particularly to its credit notwithstanding the overall positive spin, the report acknowledges that “... more effort is needed to understand these differences in results before attempting further field tests.” [emphasis mine]

The TCEQ Phase I PFTIR trials also included a limited test of an elevated flare.  The report confesses that the “... flare experiment provides valuable information for assessing logistical difficulties that might be encountered during field measurement campaigns.”  The prescient prediction of “... logistical difficulties ...” has certainly come true, in spades, in USDOJ/USEPA Enforcement Division Consent Decree field trials that are currently under way.

The TCEQ Phase I PFTIR report concludes that “... PFTIR appears to be a potentially viable method warranting further study based on the Phase I Study results ...” and that “... a second campaign should be conducted ... to validate the PFTIF method.” [emphasis mine]  The TCEQ Phase I PFTIR report concludes with three “Path Forward Recommendations;” viz.,

·        One series of tests would be conducted on the plume generator to validate the effectiveness of the proposed software and hardware modifications

·        A second series of tests would then be performed on a well instrumented ground flare to demonstrate the robustness of the PFTIR method to accurately characterize emissions from flare plumes

·        After method confirmation, a series of field tests on actual flare systems could then be scheduled

That was then (2004), this is now (2009) and the second validation campaign has yet to be conducted.  The PFTIR method confirmation has never been carried out.  Nevertheless, PFTIR is being used in USDOJ/USEPA Enforcement Division Consent Decree field trials that are currently under way, producing some scattered, uncertain, ambiguous and inexplicable results. 

It is rumored that TCEQ’s recommended, much needed and long awaited PFTIR “Phase II” study will be getting underway early next year.  Nobody knows what the test plan is but, hopefully, it will include the well thought out Phase I report recommendations.   That would be great.  It would be even greater if Phase II were actually to validate a point-and-shoot measurement and quantification technique.

As the Prince of Denmark said, “’Tis a consummation devoutly to be wished!”  While I, like others, am tired of waiting, that doesn’t justify jumping the gun and using any method that we don’t know works.  If TCEQ’s Phase II study produces one, great.  I’ll drink to that.  Do the Danes have good beer?