Update on Hg CEMS Jeffrey V. Ryan [email protected](919) 541-1437 U.S. Environmental Protection Agency Office of Research and Development Air Pollution Prevention and Control Division Research Triangle Park, NC 27711, U.S.A. OAQPS Measurement Technology Workshop 2010 December 6, 2010 They’re here to stay …
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Update on Hg CEMS - US EPA · Update on Hg CEMS Jeffrey V. Ryan [email protected] (919) 541-1437 ... Triangle Park, NC 27711, U.S.A. OAQPS Measurement Technology Workshop 2010 December
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Power Plant - Hg CEMS RATA Results Low-Level Emissions Tests
Cement Plant - Hg CEMS RATA Results Low-Level Emissions Tests
RATA TEST RESULTS MW CEMENT PLANTLow-Level Emissions Example
-1.000
-0.500
0.000
0.500
1.000
1.500
1 2 3 4 5
Run Number
Hg
Con
cent
ratio
n - u
g/m
3
REF METHTEK CEMDIFF
Source: Tekran
Cement Plant - Hg CEMS RATA Results Low-Level Emissions Tests
RATA TEST RESULTS PLANT BHigher Level Emissions Example
-20
0
20
40
60
80
100
120
140
6 7 8 9
Run Number
Hg
Con
cent
ratio
n (u
g/m
3)
REF METHTEK CEMDIFF
Source: Tekran
Source: NESCAUM 2010
Hg Emissions DataHg CEMS vs. Sorbent Traps
• See what you’re missing … Process characterization Data variability
NIST Traceability
• Certified “NIST Traceable” gas standards are needed to support regulatory applications
• EPA defines NIST Traceability• Where possible, the certified concentration is derived from
an unbroken chain of direct comparisons linked to a primary reference originating from NIST
• With collaboration from the utility industry, Hg CEM vendors and NIST, EPA has developed Interim Protocols to establish certification and continuing QA procedures for Hg0 and HgCl2 gas standards
How NIST Traceability Works
NIST ID -ICP Mass Spec
NIST Prime gas generator
Vendor 1 Prime gas generator
Vendor 2 Prime gas generator
User F gas generator
User C gas generator
User A gas generator User D gas
generator
Vendor 1 Field
Reference gas generator
Vendor 2 Field
Reference gas generator
NIST
User B gas generator
User E gas generator
Hg Calibration Gases• NIST-traceable Hg0 and Hg+2 calibration gases now available• Hg0 and Hg+2 Interim Protocols used to establish traceability
• Final NIST traceability protocols expected in the next 12-18 months
• Nominal NIST-traceable Hg0 concentrations of 0.5 µg/m3 to 300 µg/m3 now available(NIST recently extended upper end from 45 µg/m3)
• Fundamental bias (7-10%) exists between Hg0 and evaporative Hg+2 standards Reason unknown (but we’re still working on it) Does not limit NIST traceability or regulatory use of Hg CEMs
Take Home Messages …
• Hg CEMS are indeed ready for “prime time”• Now being used on multiple source categories
Cement plants, HWIs, steel plants, power plants• Promulgated monitoring procedures for Hg CEMS and
sorbent traps now available• NIST traceability available and functional
for Hg0 and Hg+2 calibration gases• NIST traceable Hg0 gases available from
~0.5 µg/m3 to 300 µg/m3
• Don’t underestimate the benefit of using Hg CEMS for process characterization.