Mercury Stack Testing –
The Right Methodology to Match
Requirements and Purpose
28th Annual Conference on the
Environment
November 12, 2013
Tim Russell – Barr Engineering Company
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So, you need to test for Mercury stack
emissions…..
• What is driving your need to test? What are your
project objectives?
• Is mercury emitted as a particle or vapor, given
your industrial process and air pollution controls?
• Is mercury emitted as elemental (Hgo) or oxidized
(Hg2+) forms?
• Do you need immediate Hg data, or can you wait
for results?
• What will be your future testing frequency?
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Most Common Stack Test Hg Emission
Measurement Methods
• EPA Method 29 – Metals emissions, particlebound and total mercury
• Ontario Hydro (ASTM D6784-02) - Elemental,
oxidized, particle-bound and total mercury
• EPA Method 30B – Vapor phase Hg using
carbon sorbent traps
• EPA Method 30A - Vapor phase Hg using
instrumental analyzer
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Particulate Matter Fundamentals - isokinetics
Isokinetic sampling to obtain a representative
sample of particles:
“Any technique for collecting airborne
particulate matter in which the collector is so
designed that the airstream entering it has a
velocity equal to that of the air passing around
and outside the collector.”
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What about the methods that also measure
particulate Hg (EPA 29 and Ontario Hydro)?
Filter
Probe
Wash
They Generate Many Sample Fractions!
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Impinger
Contents and
rinses
What about the methods that also measure
particulate Hg (EPA 29, Ontario Hydro)?
• Ontario Hydro is generally recognized as the
standard for evaluation of newer techniques
• Methods were “proven” in the 1990’s and
2000’s
• Analytical techniques have been sharpened
overtime – better detection and QA/QC
• Lab service and pricing have both improved
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What about the methods that also measure
particulate Hg (EPA 29, Ontario Hydro)?
• They generate many sample fractions that are analyzed
separately
• Non-detect fractions are added to detected fractions,
skewing the results (high)
• Method requires significant attention to detail and is
best undertaken by very experienced staff
• Sample collection is difficult and relatively expensive
• Sample analysis takes time and is relatively expensive
• Results in weeks, not real time and not days
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What about the methods for vapor phase Hg
(EPA 30A - CEMS, EPA 30B - carbon tubes)?
• Both are establishing a strong track record
through increasing use and refinement
• Real time data from CEMS is fantastic
• EPA 30A Hg CEMS are a very large investment
• EPA 30B is very easy to use and onsite analysis
is a great benefit for near-real time results
• Both are designed to capture and analyze
vapor phase Hg only
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What about the methods for vapor phase Hg
(EPA 30B - carbon tubes)?
• EPA 30B carbon tubes can capture particulate
Hg, but not in a manner designed to collect a
representative sample of particles in stack gas
stream
Glass wool plugs for carbon
retention and separation
Air Flow
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Mercury Method Comparison
Method
Measurement
Period
Hg Measurement
Type
Speciation?
Ease
Cost
Time to
Results
EPA 29
Average over
sample period
Particulate, Vapor
Phase and Total HG
No
Difficult
Medium
1-4 Weeks
Ontario
Hydro
Average over
sample period
Particulate, Vapor
Phase and Total HG
Yes
Difficult
Medium
1-4 Weeks
EPA 30B
Average over
sample period
Vapor Phase Hg
No
Easy
Low
Onsite results
to 1-2 weeks
EPA 30A
Continuous
Vapor Phase Hg
Yes
Easy with
lots of
training
High
Instantaneous
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What to consider going forward
• Lean on your stack testing provider to make informed
choices regarding Hg methodology
• EPA Method 30B is the best choice for early screening
• Ontario Hydro testing is the best choice to determine
the disposition and species of Hg being emitted
• Be prepared to discuss future measurement of Hg
emissions with regulators prior to full commitment to
any Hg reduction technology or measurement program
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