QualityAssurance Requirements for Continuous Monitoring Systems in the NOx Budget Program Robert F.

1
Quality-Assurance Requirements for Continuous
Monitoring Systems in the NOx Budget Program
Robert F. VollaroU.S. EPAClean Air Markets
Division
2
What Types of Continuous Monitoring Systems are
Required by the NOx Budget Program ?

• Continuous monitoring systems are required for
  all NOx Budget Program units, with one possible
  exception---i.e., qualifying oil and gas-fired
  units for which the low mass emissions (LME)
  methodology in 75.19 is used.
• The principal types of continuous monitoring
  systems used in the NOx Budget Program to
  quantify NOx mass emissions and heat input rate
  include
• NOx-diluent systems, which measure NOx emission
  rate in units of pounds per million Btu
  (lb/mmBtu)
• NOx concentration systems, which measure NOx
  emissions in units of parts per million (ppm)

3
What Types of Continuous Monitoring Systems are
Required by the NOx Budget Program ? (contd)

• Flow monitoring systems which measure stack gas
  volumetric flow rate in units of standard cubic
  feet per hour (scfh)
• Moisture monitoring systems, which measure the
  stack gas moisture content in units of percent
  H2O
• Diluent gas (O2 or CO2) monitoring systems (used
  for heat input rate determinations), which
  measure the O2 or CO2 concentration in the stack
  gas, in units of percent O2 or CO2
• Fuel flowmeter systems, which measure the
  quantity of oil and gas combusted in the affected
  unit, on a volumetric or mass basis
• Appendix E monitoring systems, which estimate NOx
  emission rate in lb/mmBtu, based on a correlation
  curve of heat input rate vs NOx emission rate
  (applies to oil and gas-fired peaking units, only)

4
What Types of Continuous Monitoring Systems are
Required by the NOx Budget Program ? (contd)

• The specific continuous monitoring systems
  required for your affected unit depends primarily
  on
• The type of fuel combusted
• The selected monitoring methodology and
• The mathematical equations used in the emission
  calculations.

5
What Tests are Required to Certify the NOx
Budget Program Monitoring Systems ?

• The certification requirements for Part 75 CEMS
  are found in section 75.20 (c)
• For a NOx-diluent system
• 7-day calibration error tests of the NOx and
  diluent components
• Linearity checks of both components
• Upscale and downscale cycle time tests of both
  components
• Relative accuracy test audit (RATA) of the
  system, on a lb/mmBtu basis, and a bias test
• For a NOx concentration system
• 7-day calibration error test
• Linearity check
• Cycle time test
• RATA, on a ppm basis, and a bias test

6
What Tests are Required to Certify the NOx
Budget Program Monitoring Systems ? (contd)

• For a flow monitor
• 7-day calibration error test
• RATA at 3 load levels and a bias test
• For a moisture monitoring system
• 7-day calibration error test (wet-dry O2 systems,
  only)
• Linearity check (wet-dry O2 systems, only)
• Cycle time test (wet-dry O2 systems, only)
• RATA, on a H2O basis

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What Tests are Required to Certify the NOx
Budget Program Monitoring Systems ? (contd)

• For a diluent gas monitoring system
• 7-day calibration error test
• Linearity check
• Cycle time test
• RATA, on a CO2 or O2 basis (as applicable)
• The certification test requirements for Appendix
  D and E monitoring systems are found in section
  2.1.5 of Appendix D and section 2.1 of Appendix E
• For a fuel flowmeter system
• Either calibrate the system with a flowing fluid,
  at 3 points covering the normal operating range
  of the affected unit or

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What Tests are Required to Certify the NOx
Budget Program Monitoring Systems ? (contd)

• If the flowmeter is an orifice, nozzle or
  venturi-type and it meets certain design
  criteria, you may certify it by performing a
  visual inspection and calibrating the pressure,
  delta-P, and temperature transducers
• For an Appendix E monitoring system
• Perform NOx emission rate testing at 4 load
  levels covering the operating range of the
  affected unit
• Measure the heat input rate during the NOx
  emission testing, using data from a certified
  Appendix D fuel flowmeter system in conjunction
  with the gross calorific value (GCV) of the fuel
• Construct the correlation curve of NOx emission
  rate vs heat input rate from the test data

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Are There Exceptions to These Certification
Requirements ?

• Part 75 provides the following exceptions to the
  continuous monitoring system certification
  requirements. Specifically
• Peaking units are exempted from 7-day calibration
  error testing (Appendix A, sections 6.3.1 and
  6.3.2)
• NOx span values of 50 ppm or less are exempted
  from 7-day calibration error testing (Appendix A,
  section 6.3.1)
• NOx span values of 30 ppm or less are exempted
  from linearity checks (Appendix A, section 6.2
  and Appendix B, section 2.2.1)
• Flow RATAs may be done at fewer than 3 load
  levels if the source has an approved petition or
  technical justification (Appendix A, sections
  6.5.2 (c) and (e)).

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Are There Exceptions to These Certification
Requirements ? (contd)

• A default moisture value (from Part 75 or
  approved by petition) may be used in lieu of
  certifying a continuous moisture monitoring
  system (sections 75.11(b) and 75.12(b)).
• For saturated gas streams, you may use a
  temperature sensor and the psychrometric chart to
  monitor the stack gas moisture content. A DAHS
  verification at 3 representative temperatures is
  required. (section 75.20(c)(7)).

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What Performance Specifications Must be Met for
Initial Certification ?

• For CEMS, the performance specifications for
  initial certification are found in Part 75,
  Appendix A, sections 3.1 through 3.5
• The primary performance specifications are
  expressed as percentages (e.g., of span, of
  reference gas value, relative accuracy).
• There are a number of alternative specifications,
  expressed as the absolute difference between the
  mean values of the reference and CEMS
  measurements. These alternative specifications
  provide relief from the primary specifications,
  for low-emitting sources and low span values.
• The CEMS may be certified either by meeting the
  primary or the alternative specifications

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What On-Going Quality-Assurance is Required for
the Monitoring Systems ?

• After initial certification, periodic
  quality-assurance (QA) testing of all Part 75
  continuous monitoring systems is required
• For continuous emission monitoring systems
  (CEMS), these QA test requirements are found in
  either
• Appendix B of Part 75, for sources that report
  emissions data year-round or
• Section 75.74(c), for sources that report
  emissions data only during the ozone season

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What On-Going Quality-Assurance is Required for
the Monitoring Systems ? (contd)

• For fuel flowmeter systems, the on-going QA test
  requirements are found in section 2.1.6 of Part
  75, Appendix D
• For Appendix E monitoring systems, the on-going
  QA test requirements are found in sections 2.2
  and 2.3 of Part 75, Appendix E

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On-Going QA Requirements for Year-Round Reporters

• For NOx Budget sources that report emissions data
  year-round
• If a CEMS-based methodology is used, QA testing
  of of the CEMS is required at three basic
  frequencies
• Daily
• Quarterly
• Semiannual/Annual
• For sources using fuel flowmeters, the basic QA
  test frequency is annual, but may be extended up
  to 5 years (20calendar quarters) if certain
  conditions are met
• For Appendix E sources, the basic QA test
  frequency is once every 5 years (20 calendar
  quarters), provided that certain conditions are
  met

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On-Going QA Requirements for Year-Round
Reporters (contd)

• Periodic QA Testing of CEM Systems
• Daily Assessments
• Calibration error tests (required for all gas
  and flow monitors)
• Interference checks (required for all flow
  monitors)
• Quarterly Assessments
• Linearity checks
• Required for gas monitors in every QA operating
  quarter (i.e., a calendar quarter with gt 168 hrs
  of unit operation
• For dual-range analyzers, required on each range
  used in the QA quarter
• Required at least once every 4 calendar quarters
  on each range, regardless of unit operating hours
  or whether the range was used
• NOx span values lt 30 ppm are exempted
• A 168 unit operating hour grace period is
  available

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On-Going QA Requirements for Year-Round
Reporters (contd)

• Flow-to-load ratio test
• Required for units with stack flow monitors, to
  assess flow monitor accuracy in-between
  successive annual RATAs
• Required only in QA operating quarters
• Analyzes a segment of the quarterly flow rate
  data. Compares hourly flow-to-load ratios to a
  reference ratio determined during the most recent
  normal load RATA
• As an alternative, the test may be done on a
  gross heat rate (GHR) basis, i.e., the ratio of
  heat input rate to load
• Complex exhaust configurations may be exempted
  from the flow-to-load test by petition under
  75.66
• Leak check
• Required only for differential pressure-type
  stack flow monitors
• Required only in QA operating quarters
• A 168 unit/stack operating hour grace period is
  available

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On-Going QA Requirements for Year-Round
Reporters (contd)

• Semiannual and Annual Assessments
• RATA
• Required for gas monitoring systems, flow
  monitors, and moisture monitoring systems
• Depending on RA achieved in the last RATA, the
  next test is required either annually (within 4
  QA operating quarters) or semiannually (within 2
  QA operating quarters)
• Gas and moisture system RATAs are always
  performed at normal load
• The basic flow RATA requirement is at 2 loads.
  From year-to-year, sources can qualify for
  single-load test if gt 85 of load data since the
  last annual RATA is in one load band (Low, Mid,
  or High)
• Limited extension of RATA deadlines is allowed
  for non-QA operating quarters, up to 8 calendar
  quarters between successive RATAs
• A 720 unit operating hour grace period is
  available
• A bias test is required for NOx systems and flow
  monitors

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On-Going QA Requirements for Year-Round
Reporters (contd)

• Fuel flowmeter accuracy tests
• Required once every 4 fuel flowmeter QA
  operating quarters (i.e., a quarter in which the
  fuel measured by the flowmeter is combusted for
  gt 168 hrs)
• The accuracy test consists of either calibration
  against a flowing fluid or (for orifice, nozzle
  and venturi-type meters that were certified by
  design) calibration of the transmitters
• For orifice, nozzle or venturi-type flowmeters
  that were certified by design, a visual
  inspection of the primary element is also
  required every 3 years
• Accuracy test deadlines may be extended for
  infrequent use of the fuel flowmeter (non-QA
  operating quarters) or if the optional quarterly
  fuel flow-to-load ratio test is performed and
  passed (Appendix D, 2.1.7)
• The maximum possible extension of an accuracy
  test deadline is 20 calendar quarters from the
  quarter of the last test

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On-Going QA Requirements for Year-Round
Reporters (contd)

• 5-year assessments
• For stack flow monitors, a 3-load RATA is
  required once every 5 calendar years
• For Appendix E sources, the basic re-testing
  frequency is once every 5 years (20 calendar
  quarters), provided that none of the monitored
  parameters are outside the acceptable ranges for
  more than 16 consecutive operating hours. An
  additional re-test is required when this
  condition is not met.

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On-Going QA Requirements for Year-Round
Reporters (contd)

• When must the on-going QA tests begin ?
• Daily assessments---These requirements become
  effective as of the date when certification
  testing of the CEMS is completed (i.e., date of
  provisional certification)
• Quarterly assessments---These assessments begin
  in the quarter following the quarter in which the
  CEMS is provisionally certified
• Semiannual, annual and 5-year assessments---Reckon
  the deadline for the next test starting with the
  quarter following the quarter in which the
  monitoring system is provisionally certified
• See Appendix B, sections 2.1, 2.2, and 2.3

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On-Going QA Requirements for Ozone Season-Only
Reporters

• For NOx Budget sources that report emissions data
  on an ozone season-only basis, there are QA test
  requirements both
• Outside the ozone season (October 1-April 30)
  and
• Inside the ozone season (May 1-September 30)
• For CEMS-based methodologies
• Daily calibrations of all monitors are required
  inside the ozone season. Outside the ozone
  season, calibrations are required from the hour
  of any passed off-season RATA or linearity check,
  through April 30
• Daily interference checks of flow monitors are
  required inside the ozone season. Outside the
  ozone season, these checks are required from the
  hour of any passed flow RATA, through April 30

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On-Going QA Requirements for Ozone Season-Only
Reporters (contd)

• A linearity check of each gas monitor is required
  outside the ozone season. Inside the ozone
  season, linearity checks are required in the 2nd
  and 3rd quarters, if those quarters are QA
  operating quarters.
• A 168 operating hour grace period is allowed at
  the beginning of the ozone season for the
  off-season check, if a linearity was passed in
  the previous year and if the unit operated lt 336
  hrs in the last ozone season
• No grace periods are allowed for the required 2nd
  and 3rd quarter linearity checks inside the ozone
  season
• Only unit operating hours in May and June are
  used to determine whether the 2nd quarter is a QA
  operating quarter
• For flow monitors, the flow-to-load ratio test is
  required only in the 2nd and 3rd quarters, if
  those quarters are QA operating quarters.

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On-Going QA Requirements for Ozone Season-Only
Reporters (contd)

• For DP-type flow monitors, leak checks are
  required only in the 2nd and 3rd quarters, if
  those quarters are QA operating quarters.
• RATAs of all gas, flow, and moisture monitoring
  systems are required semiannually or annually.
• The RATAs may be done either inside or outside
  the ozone season
• Depending on the RA achieved, the frequency is
  semiannual or annual and the next test is due in
  either 2 or 4 calendar quarters.
• The QA operating quarter concept does not apply.
• The window of data validation extends either to
• The end of the 2nd quarter following the quarter
  of the RATA, if the RATA frequency is semiannual
  or
• The end of the 4th quarter following the quarter
  of the RATA, if the RATA frequency is annual.

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On-Going QA Requirements for Ozone Season-Only
Reporters (contd)

• If a scheduled off-season RATA is not completed
  by April 30
• A 720 operating hour grace period is available if
  a RATA was passed in the previous year and the
  unit operated lt 336 hrs in the last ozone season
• If you do not qualify for the grace period, you
  may use the conditional data validation
  procedures in 75.20(b)(3), with certain
  restrictions
• Grace periods do not apply when the owner or
  operator elects to schedule and perform RATAs
  inside the ozone season
• A bias test is required for all NOx monitoring
  systems and flow monitors.
• For flow monitors, 2-load RATAs are required for
  routine QA, and a 3-load test must be performed
  once every 5 years. The option to qualify for
  single-load annual flow RATAs is not available to
  ozone season-only reporters.

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On-Going QA Requirements for Ozone Season-Only
Reporters (contd)

• Accuracy tests of fuel flowmeters and Appendix E
  re-tests are required at the same frequency as
  for year-round reporters. All calendar quarters
  in the year are included when determining the
  test deadlines.

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What Performance Specifications Must be Met for
On-Going QA ?

• The performance specifications that must be met
  for the on-going QA tests of the continuous
  monitoring systems are basically the same as for
  initial certification, with one notable exception
• For CEM systems
• The daily calibration error specifications in
  section 2.1.4 of Appendix B are less stringent
  than the 7-day calibration error test
  specifications in section 3.1 of Appendix A.
• The linearity specifications are the same as in
  section 3.2 of Appendix A

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What Performance Specifications Must be Met for
On-Going QA ? (contd)

• The RATA specifications are the same as in
  sections 3.3.2 through 3.3.7 of Appendix A.
• For reduced RATA frequency (i.e., annual vs
  semiannual), the specifications are found in
  section 2.3.1.2 of Appendix B and are summarized
  in Figure 2 of Appendix B.
• For fuel flowmeter systems, the accuracy
  requirements for on-going QA tests are the same
  as for initial certification and are found in
  sections 2.1.5 and 2.1.6 of Appendix D