Comparison of MACT CC & NSPS Subpart Ja Requirements -...

Presented by:

Stephen Walls, P.E.

Trihydro Corporation

Comparison of MACT CC & NSPS Subpart Ja Requirements - Flares

Agenda

• Applicability

• Regulated Pollutants

• Emissions Limitations

• Compliance Strategy

• Monitoring

• Calibration and QA/QC

• Data reduction

• Root Cause Analysis/Corrective Action Analysis (RCA/CAA)

• Compliance Documents

Comparison of MACT CC & NSPS Subpart Ja Requirements -Flares

Applicability

• NSPS Subpart Ja

• Refinery flare C-M-R after 6/24/2008

• New connection or increase flow = modification

• Regardless of assist type - non-assisted, air, steam, pressure

• MACT Subpart CC

• Located at HAP major refinery - ≥ 10 tpy / 25 tpy HAPs

• Control one of nine source categories listed – don’t forget FCC,

CRU, and SRU in MACT UUU

• Vent gas contains one of 27 HAPs listed in Table 1 = regulated

material


• Older flares (C-M-R on or

before 6/24/08) – excluded

Ja, subject to CC

• Special use flares (e.g.,

hydrogen) – may be subject to

Ja, excluded CC (no regulated

material)

• Fuel gas used as purge/sweep

could trigger MACT CC

• Intermittent flares – addressed

in RTC for CC, not Ja

• Temporary flares – addressed

in RTC for both regs.

Applicability (continued)


Regulated Pollutants

• NSPS Subpart Ja (criteria pollutants)

• Sulfur dioxide (SO2)

• Reduce vent gas flow/reduce TRS concentration = less SO2

emissions

• Other criteria pollutants – PM, NOX, CO, VOC

• Reduce vent gas flow = less emissions of other criteria pollutants


Regulated Pollutants (continued)

• MACT Subpart CC (organic HAPs)

• 27 Table 1 HAPs – and other inadvertent HAPs

• Continuous smokeless operation

• Low tip velocity

• Maintain vent gas heat content


Maintain destruction efficiency = lower organic

HAP emissions

Emissions Limitations – NSPS Ja

• Sulfur dioxide

• 162 ppmv H2S flare vent gas

• Determined hourly on a 3-hr rolling average basis

• Sulfur dioxide and other criteria pollutants

• Baseline flow(s) = magic number(s)

• Set by refinery after minimization assessment

• Do not need to include pilot / purge gas (introduced after water seal)

• Multiple baselines allowed – different operating scenarios


Emissions Limitations – MACT CC

• Organic HAPs

• Compliance with enhanced operating standards = improve

destruction efficiency

• Continuous operation of a pilot flame*

• Operate without visible emissions (VE)*

• Flare tip velocity < 60 fps or < 400 fps and vmax*

• Combustion zone heat content > 270 Btu/scf*

• Dilution parameter > 22 Btu/ft2


Emissions Limitations – MACT CC (continued)

• Enhanced operating standards (*) similar to general

requirements §60.18 and §63.11 – not the same

• Gen. requirements different for different flare types – MACT CC

consistent for different flare types

• Only reference non-assisted, air assisted, and steam assisted

flares – MACT CC not limited to these types

• EPA feels general requirements inadequate


Compliance Strategy – NSPS Ja

• Hard numeric limit H2S concentration flare vent gas

• Exceedance triggers excess emissions reporting

• Refinery established baseline flow(s)

• RCA/CAA process

• Flare SO2 emissions and elevated vent gas flow (Qvg) can trigger

analyses

• Identify root cause and implement corrective actions in 45 days

• Documentation

• Driving toward flare gas recovery – flare minimization

assessment/cost-benefit analysis


Compliance Strategy – MACT CC

• Enhanced operating standards

• Continuous pilot light

• No visible emissions – when vent gas below smokeless capacity

• Actual tip velocity below applicable numeric standard

• NHVcz above 270 Btu/scf

• NHVdil above 22 Btu/ft2 (air assisted flares)


Compliance Strategy – MACT CC (continued)

• Vmax, NHVcz and NHVdil incorporate flare gas composition data

(continuous GC, 8-hr sampling, or calorimeter)

• Pilot light requirements apply – regulated material routed to

flare

• VE requirements apply – regulated material routed to flare

AND Qvg less than smokeless capacity

• vtip requirements apply – regulated material routed to flare for

at least 15-min AND Qvg less than smokeless capacity

• NHVcz and NHVdil requirements apply – regulated material

routed to the flare for at least 15-minutes


Compliance Strategy – MACT CC (continued)

• Smokeless capacity = magic number

• Single value – not dependent upon operating scenarios

• May require input manufacturer/engineering

• May need to consider MW of vent gas

• Emergency flaring provisions and RCA/CAA trigger

• Driving toward flare gas recovery – flare minimization

assessment/cost-benefit analysis during S/U and S/D


Monitoring – NSPS Ja

• Continuous vent gas flow – RCA trigger

• Does not specifically address volumetric vs. mass flow meters

• Continuous H2S monitoring – compliance with the 162 ppmv

• Continuous sulfur monitoring - SO2 RCA trigger

• TRS monitoring – not meant to be only H2S, COS, and CS2 (total

sulfur (Method 16A)

• H2S monitoring – develop total sulfur-to-H2S ratio through sampling

• Representative SO2 monitoring

• Single TRS or H2S monitor can be used for both – meet span

requirements

• Sampling approach – approved using AMP


Monitoring – MACT CC

• Continuous vent gas flow – Ja required

• Volumetric (standard P and T corrected)

• Mass – converted to volumetric with gas composition data or default

• Continuous P and T – engineering calculation for volumetric flow

• Continuous assist media (air or steam) and supplemental fuel

flow – not Ja required

• Same monitoring options as vent gas flow

• Convert mass flow using default values – gas composition may be

required for refinery fuel gas

• Using fan speed and curve acceptable for air-assisted flares


• Continuous pilot light

monitoring

• Thermocouple, ultraviolet,

infrared, etc.

• Redundancy

• Gas composition monitoring

• Continuous GC – provide MW and

speciation, automatic

• 8-hour sampling – provide MW

and speciation, manual

• Continuous calorimeter (optional

H2 analyzer) – no MW or

speciation, could rule out mass

flow monitoring option

Monitoring – MACT CC (continued)


Monitoring – MACT CC (continued)

• Visible emissions

• Method 22 observations

• Minimum daily for 5-minutes

• 5-minute when VE routinely observed (even if daily already

performed)

• VE observed 1-min during 5-min observation – extend to 2-hrs

• Video surveillance

• Continuous – one frame every 15 seconds (time and date stamped)

• Video routed to continuously manned location


Monitoring (continued)

• NSPS Ja requirements apply

• Any time vent gas is routed to the flare

• MACT CC requirements apply

• When regulated material (27 HAPs in Table 1) routed to flare


Calibration and QA/QC

• Vent gas flow meters – both regs.

• Same accuracy and calibration frequency

• Quarterly visual inspection – waived under MACT CC if redundant

sensors

• MACT CC requires additional visual inspection when flow exceeds

manufacturer maximum flow rate for 24-hours


Calibration and QA/QC (continued)

• Pressure monitoring devices

• Different requirements in Ja and CC

• Ja calibrate quarterly and after manufacturer range exceedance

• CC calibrate annual and after manufacturer range exceedance

• CC requires quarterly inspection – waived if redundant sensor

• CC review pressure data to check for monitor blockage


Calibration and QA/C (continued)

• MACT CC Table 13 (nothing in NSPS Ja)

• Temperature

• GC/Calorimeters – additional GC requirements in §63.671(e)

• Assist media and supplemental fuel flow

• Sulfur/H2S monitoring devices (only NSPS Ja)

• Span differs by configuration

• Performance specification and test method differs by type of

device – H2S, TRS/total sulfur, SO2


Data Reduction – NSPS Ja

• Calculate rolling 24-hr flow

• Compare rolling 24-hr vent gas flow to appropriate BL + 500,000

scf/24-hr (RCA trigger)

• Calculate 3-hr rolling average H2S concentration from hourly data

• Compare 3-hr rolling average to 162 ppmv limit

• Calculate SO2 emissions for each hour using total sulfur/TRS

data and vent gas flow and sum – assume 99 percent conversion

• Approx. equation -

• Compare to 500 lbs/24-hr (RCA trigger)

• Some data may require moisture correction


Data Reduction – MACT CC

• Review of pilot light and VE observation data

• Determine if standards exceeded

• Calculate volumetric flow, if required

• Compare volumetric flow to smokeless capacity

• Sum volumetric flow (vent gas, assist media, and supplemental fuel) for each

15-minute block

• Calculate NHVvg vtip, and vmax for each 15-minute block using vent gas flow

and composition data

• Compare vtip to applicable standard – not hard limit, changes

• Calculate NHVcz, and NHVdil for each 15-minute block

• Compare to applicable standard

• Two different methods to calculate (direct and feed-forward) – consistent for each

flare


RCA/CAA

• RCA/CAA process is basically the same for both regs.

• 45-days and document

• MACT CC – allows single RCA if both triggering conditions met

during same event

• MACT CC – does not exclude planned S/U and S/D events

• Reporting period – Ja (24-hrs), CC (15-min)


RCA/CAA (continued)

• Triggering conditions are different

• NSPS Ja

• Emissions ≥ 500 lbs SO2/24-hr period

• Vent gas flow ≥ 500,000 scf above established baseline flow(s)

• MACT CC

• Vent gas flow exceeds smokeless capacity, regulated material is

routed to the flare and either

• VE standard is exceeded or

• vtip standard is exceeded


Compliance Documents

• Both regs. require flare management plans (FMPs)

• Ancillary connection list

• General flare description

• MACT CC requires more assist media info

• Minimization assessment

• NSPS Ja - routine, fuel gas imbalance, and FGRU outage

• MACT CC - S/U, S/D, and emergency release

• Magic numbers

• NSPS Ja – baseline flow(s)

• MACT CC – smokeless capacity

• MACT CC requires detailed CPMS Plan


Conclusion

• Complying with MACT Subpart CC

• Leverage vent gas flow monitors installed for NSPS Ja

• Incorporate existing pilot light monitoring

• Incorporate existing assist media flow monitoring

• Evaluate current VE compliance and vent gas composition

determination procedures

• Engage engineering early to determine unobstructed area and

smokeless capacity

• Get DCS engaged early for data reduction


Presenter


Stephen Walls, P.E.

Senior Engineer

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Comparison of MACT CC & NSPS Subpart Ja Requirements -...

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