Implementing Rectangular Duct Wall Effects (CTM-041)

1
Implementing Rectangular Duct Wall Effects
(CTM-041)

• John Schakenbach, USEPA
• Steve Norfleet, RMB Consulting Research, Inc.
• EPRI CEM User Group
• Milwaukee, WI
• May 4-6, 2004

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What is CTM-041?

• CTM-041 is an optional conditional test method to
  account for wall effects in rectangular ducts or
  stacks

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Whats a Conditional Test Method?

• A CTM has been evaluated by EPA, but is not
  published in the Code of Federal Regulations
• Must be approved by EPA before being used to meet
  Parts 60, 61, 63 or 75
• May be used by, e.g., Title V permits and SIPs
  with EPA oversight and public notice and comment
• EPA staff may not be the technical experts
• Additional info at www.epa.gov/ttn/emc, then
  click on Methods

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What is a Rectangular Duct Wall Effect?

• Velocity decreases to zero at duct wall
• More wall effects than circular stack due to
  higher circumference to cross-sectional area ratio

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Why is This a Problem?

• Neither Method 2 nor 2H account for these wall
  effects may cause overreporting of emissions

6
How Do I Use CTM-041?

• DR or AAR submits a one time written request to
  EPA (for address, go to www.epa.gov/airmarkets,
  click on Recent Additions near top left corner,
  and scroll to December 18, 2003)
• Request may cover all units for which DR/AAR is
  responsible

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How Do I Use CTM-041?

• Request must contain
• Plant name
• Unit ID
• Stack/pipe ID
• ORISPL
• Wall effects start date and time

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How Do I Use CTM-041?

• Part 75 or NOx SIP Call units may provisionally
  apply CTM-041 retroactively to Jan 1 of the year
  CTM-041 is performed, but no earlier than Jan 1,
  2004. If necessary, EDRs may be resubmitted.
• All EPA approvals will be conditioned
• The rectangular duct cross-sectional area
  may not be adjusted to account for any build-up
  of particulate matter or other material in the
  bottom of the duct when calculating stack gas
  volumetric flow.

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Get Detailed Info

• www.epa.gov/airmarkets, then click on Recent
  Additions near top left corner and scroll to
  February 2, 2004 and December 18, 2003
• A copy of CTM-041
• General info on conditional test methods
• Where to send the request to use CTM-041
• Detailed EDR reporting instructions
• Spreadsheets
• Most recent version of MDC software (v 4.2.46) to
  QA data

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Summary of CTM-041

• May use site-specific default WAF, or
• May make wall effects measurements and calculate
  average WAF using 3 or more test runs
• The run (for default) or 3 run average (for
  measured) used to calculate a WAF must have same
  number of Method 1 traverse points as is used in
  the most recent flow monitor RATA
• Not load level dependent
• Not necessarily connected with a RATA
• WAF entered as correction to cross-sectional area
• During RATA, WAF would be applied to both
  installed flow monitor and RM data

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Summary of CTM-041

• A site-specific default WAF can be calculated
  using Section 8.4.2 of CTM-041, and either a run
  from the most recent flow RATA, or from a single
  Method 2, 2F or 2G non-RATA run.
• The run used to calculate a default WAF must have
  same number of Method 1 traverse points as is
  used in the most recent flow monitor RATA

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Report CTM-041 Using RT 910s

• Each quarter you use WAF, report 6 to 11 RT 910s
• The WAF RT 910s must be reported consecutively
  and the sequence must be uninterrupted
• If non-WAF RT 910s are required, separate them
  from WAF RT 910s with blank RT 910s

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Report CTM-041 Using RT 910s

• (1) Report RECTANGULAR DUCT WAF
• (2) Report width of rectangular duct at test
  location
• (3) Report depth of rectangular duct at test
  location
• (4) Report the WAF applied to flow rate data
• (5)Indicate WAF calculation approach, I.e.,
  report D for default or T for tested
  (measured) value
• (6) Report the date on which WAF was first
  applied to flow data

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Report CTM-041 Using RT 910s

• (7) If WAF is a measured value, report date of
  WAF test
• (8) If WAF is a measured value, report the number
  of runs in the WAF test
• (9) If WAF is a measured value, report the number
  of Method 1 traverse points in WAF test runs
• (10) If WAF is a measured value, report the
  number of test ports at which measurements were
  made during WAF test runs
• (11) Report number of Method 1 traverse points in
  flow RATA test runs. This record required only
  if a flow RATA was done during the quarter using
  Method 2, 2F, or 2G, corrected for wall effects
  with a measured WAF.

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Report CTM-041 Using RT 910s

• Report the RT 910s in each quarterly EDR for as
  long as the WAF is used. If a new WAF is
  determined, update the RT 910s.

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Reporting Example 1

• Unit 2 discharges through a rectangular stack 14
  ft wide and 12.5 ft deep. A certified flow
  monitor is installed on the stack. A default WAF
  of 0.9650 is obtained using CTM-041, the WAF is
  first applied to the flow data on Oct 15, 2003.
• In this example, the following WAF information
  is required to be reported in RT 910 in the 4Q
  2003 EDR
• 9102 RECTANGULAR DUCT WAF
• 9102 14.0
• 9102 12.5
• 9102 0.9650
• 9102 D
• 9102 20031015

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Reporting Example 2

• Unit 3 has a flow monitor in a rectangular duct
  10.3 ft wide and 8.9 ft deep. On Oct 15, 2003,
  CTM-041 is used to obtain a measured WAF. Three
  wall effects runs are performed with 12 Method 1
  traverse points per run, measured at 4 different
  test ports, and an average WAF of 0.9550 is
  obtained. The WAF is applied to the flow data
  starting Oct 16, 2003. The annual flow RATA for
  Unit 3 is performed on Dec 10, 2003 using Method
  2, with 12 Method 1 traverse points per run. The
  measured WAF is applied to the reference method
  flow rate data.

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Reporting Example 2

• In Example 2, the following WAF information is
  required to be reported in RT 910 in the 4Q 2003
  EDR
• 9103 RECTANGULAR DUCT WAF
• 9103 10.3
• 9103 8.9
• 9103 0.9550
• 9103 T
• 9103 20031016
• 9103 20031015
• 9103 3
• 9103 12
• 9103 4
• 9103 12 Note This RT 910 would not be
  submitted
• every quarter

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Hints Regarding Flow-to-Load

• WAF may cause flow to decrease by about 5 which
  may cause flow-to-load test failure if the RATA
  on which reference Q/L is based was unadjusted
  for WAF. Effect is temporary and will disappear
  when next normal load flow RATA is done and WAF
  is applied to it.

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Hints Regarding Flow-to-Load

• In interim, if the flow-to-load test is failed
• Copy your quarterly flow rate data, export it
  outside of DAHS, perform the flow-to-load
  analysis using uncorrected hourly flow rates
  (uncorrected flow reported flow / WAF). If you
  exercise this option, report results in RT 606
  and put a note in RT 910 (insert a blank RT 910
  to separate this comment from the required
  sequence of RT 910s) indicating that WAF was
  removed from flow rate data before running
  flow-to-load ratio test. Keep results of data
  analysis on-site in format suitable for
  inspection.

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Hints Regarding Flow-to-Load

• In RT 220, report the WAF corrected flow in
  columns 29 and 39 whether or not you remove WAF
  from flow rate data to perform flow-to-load ratio
  test

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Reporting CTM-041 Data
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Sources Approved to Use CTM-041
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For a Copy of Presentation

• www.epa.gov/airmarkets, click on Recent
  Additions near top left corner
• or
• John Schakenbach
• Phone [phone]
• schakenbach.john_at_epa.gov