Quality-Assurance Requirements for Continuous Monitoring by xiaohuicaicai

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									Quality-Assurance Requirements for
Continuous Monitoring Systems in
     the NOx Budget Program

             Robert F. Vollaro
                 U.S. EPA
         Clean Air Markets Division
    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)
 What Types of Continuous Monitoring
Systems are Required by the NOx Budget
          Program ? (cont’d)
– 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)
    What Types of Continuous Monitoring
   Systems are Required by the NOx Budget
             Program ? (cont’d)
• 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.
 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
What Tests are Required to Certify the NOx
 Budget Program Monitoring Systems ?
                 (cont’d)
 – 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
 What Tests are Required to Certify the NOx
  Budget Program Monitoring Systems ?
                  (cont’d)
   – 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
What Tests are Required to Certify the NOx
 Budget Program Monitoring Systems ?
                 (cont’d)
     • 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
 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)).
Are There Exceptions to These Certification
         Requirements ? (cont’d)
 – 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)).
  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
     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
    What On-Going Quality-Assurance is
    Required for the Monitoring Systems ?
                   (cont’d)
• 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
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
On-Going QA Requirements for Year-Round
         Reporters (cont’d)
• 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 > 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 < 30 ppm are exempted
            – A 168 unit operating hour grace period is available
On-Going QA Requirements for Year-Round
             Reporters (cont’d)
    • 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
On-Going QA Requirements for Year-Round
             Reporters (cont’d)
 – 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 > 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
On-Going QA Requirements for Year-Round
             Reporters (cont’d)
    • 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
          > 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
On-Going QA Requirements for Year-Round
             Reporters (cont’d)

 – 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.
On-Going QA Requirements for Year-Round
             Reporters (cont’d)
 – 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
    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
 On-Going QA Requirements for Ozone
    Season-Only Reporters (cont’d)
– 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 < 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”.
 On-Going QA Requirements for Ozone
    Season-Only Reporters (cont’d)
– 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.
On-Going QA Requirements for Ozone
   Season-Only Reporters (cont’d)
 • 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 < 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.
    On-Going QA Requirements for Ozone
       Season-Only Reporters (cont’d)
• 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.
   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
  What Performance Specifications Must be
     Met for On-Going QA ? (cont’d)
   – 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

								
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