Refinery Flares

3/9/2016 RTR Flare Provisions

Flares

Stephen WallsAir Permitting EngineerTrihydro Corporation


Presentation Topics• General Overview

• Definitions

• Applicability

• Enhanced Operational Standards Flares

• Flare Pilot Flame

• Visible Emissions

• Flare Tip Velocity

• Combustion Zone Heating Value

• Dilution Parameter


Rule Overview• Current 40 CFR 63.11 and 40 CFR 60.18 insufficient to ensure flares meet

control requirements

• Focus on destruction efficiency• Flare destruction efficiency confirmed by compliance with enhanced operational

and work practice standards (§63.670)• Enclosed combustion device destruction efficiency (98 percent) or outlet

concentration (20 ppmv) confirmed via testing (§63.645)• PFTIR monitoring to confirm 98 percent destruction efficiency technically

infeasible to apply on continuous basis

• Existing flare compliance date – January 30, 2019

• Incorrect to assume FGR cost-effective for all flares (case-by-case)

• Did not finalize ban on flaring halogenated vent streams


Definitions• Regulated material - contains HAP listed in Table 1,

likely includes fuel gas used as sweep or purge gas

• Flare - combustion device lacking an enclosed combustion chamber that uses an uncontrolled volume of ambient air to burn gases. For the purposes of this rule, the definition of flare includes, but is not necessarily limited to, air-assisted flares, steam-assisted flares and non-assisted flares.

• Incinerators/thermal oxidizers – have an enclosed combustion chamber that uses a controlled volume of ambient air to burn gases

• Process heaters/boilers – enclosed combustion devices that transfer heat energy to process streams or that extracts useful energy in the form of steam


ApplicabilityFlares used as air pollution control device (APCD) for the following affected emission sources at major facilities

Source type Regulation prior to February 1, 2019

Volatile organic liquid storage vessels Part 60, subpart Kb

Benzene storage vessels Part 61, subpart Y

Wastewater treatment Part 61, subparts FF (benzene waste)Part 63, subpart G (SOCMI NESHAP)

Miscellaneous process vents 40 CFR 63.11 (b)

Equipment leaks Part 60, subpart VV or §§63.172 and 63.180

Gasoline loading racks Part 63, subpart R

Marine tank vessel loading Part 63, subpart Y


ApplicabilityCatch all

•Flares used as APCD to comply with provisions of parts 60 and 61 subject to 40 CFR 60.18 and Subpart CC

•Flares used as APCD to comply with provisions of part 63 subject to 40 CFR 63.11 and Subpart CC

•Flares receiving gas from fuel gas systems

• One set of operational standards – applies to standby flares, emergency flares, non-conventional flares (e.g., pressure-assisted, ground, enclosed), and temporary flares


Pilot Flame PresenceRequirement/Deviation [§63.670 (b)]• A pilot flame present at all times

when regulated material is routed to flare

• Deviation – each 15-min block with at least 1-min where no pilot flame is present

• No pilot flame in different 15-min blocks from the same event are separate deviations (could apply if refinery fails to re-light pilot in same 15-min block)

Monitoring [§63.670 (g)]• Continuously monitor for

presence of a flame with thermocouple, ultraviolet beam sensor, infrared sensor, or other device capable of detecting if flame is present

• Rule does not specify thermocouple set point, but Table 13 indicates temperature monitor does not need to be accurate to ± 1 percent


Visible Emissions • First letter of each bullet should be

capitalized, and any proper nouns following should be capitalized also. Any other words should be lower case.

Requirement/Deviation [§63.670 (c)]

• No visible emissions (VE) when • Vent gas flow is below smokeless capacity

and

• Regulated material is routed to flare

• Deviation – greater than 5-min with VE during any 2 consecutive hours


Visible Emissions - ContinuedMonitoring [§63.670 (h)]• Observe while regulated material is being routed to flare• Initial demonstration Method 22 observation for 2 hours – newly-

affected flares• Subsequent observations

• Method 22 (40 CFR part 60, Appendix A-7)• At least daily observation for 5-min

• Initiate 5-min observation when visible emissions routinely observed

• If observed for more than one minute, extend observation to 2 hours

• 2 hour observation period is complete if 5-minutes of visible emissions observed


Visible Emissions - ContinuedMonitoring [§63.670 (h)]• Video surveillance

• Continuously record (at least one frame every 15 seconds with time and date stamps)

• Cameras positioned suitable for observations

• Output routed to control room or other continuously manned area


Flare Tip Velocity, VtipRequirement/Deviation [§63.670 (d)]

• Actual Vtip less than 60 feet per second or

• Vtip must be less than 400 fps and also the maximum allowable flare tip velocity (Vmax) calculated per

𝑳𝑳𝑳𝑳𝑳𝑳𝟏𝟏𝟏𝟏 𝑽𝑽𝒎𝒎𝒎𝒎𝒎𝒎 =𝑵𝑵𝑵𝑵𝑽𝑽𝒗𝒗𝑳𝑳 + 𝟏𝟏,𝟐𝟐𝟏𝟏𝟐𝟐

𝟖𝟖𝟖𝟖𝟏𝟏

where NHVvg is the net heating value of the flare vent gas

• Applies when regulated material is routed to flare for at least 15-min and vent gas flow less than smokeless design capacity

• Could present an issue when flaring heavier gases combined with lower Btu gases (Vmax < 400 fps)


Flare Tip Velocity, Vtip - ContinuedMonitoring [§63.670 (i)]• Flare vent gas flow (Qcum or Qvg)

• Continuously measure, calculate, and record volumetric flow in header or sub headers, including supplemental fuel

• STP correction – 68 °F and 1 atm• Other monitoring options when molecular weight determined from

compositional analysis, paragraph (j)• Mass flow meters acceptable, convert to volumetric flow

𝑸𝑸𝒗𝒗𝑳𝑳𝒗𝒗 = 𝑸𝑸𝒎𝒎𝒎𝒎𝒎𝒎𝒎𝒎𝑴𝑴𝑴𝑴𝒕𝒕

× 𝟑𝟑𝟖𝟖𝟖𝟖.𝟑𝟑


Flare Tip Velocity, Vtip - ContinuedMonitoring [§63.670 (i)]

• Continuous pressure/temperature monitoring systems and engineering calculations acceptable

• Different methods can be used for different streams, as long as all streams are included


Flare Tip Velocity, Vtip - ContinuedMonitoring [§63.670 (i)]Assist steam flow (Qs)

• Continuously measure, calculate, and record volumetric flow of steam

• STP correction – 68 °F and 1 atm

• Other monitoring options, MWt = 18 lb/lb-mol• Mass flow meters acceptable, convert to volumetric flow using same equation

• Continuous pressure/temperature monitoring systems and engineering calculations acceptable


Flare Tip Velocity, Vtip - ContinuedMonitoring [§63.670 (i)]• Assist air (Qa,premix and Qa,perimeter)

• Continuously measure, calculate, and record volumetric flow of air• Pre-mix and perimeter assist air monitored separately• STP correction – 68 °F and 1 atm

• Continuously monitoring fan speed or power and using fan curves is acceptable

• Other monitoring options, MWt = 29 lb/lb-mol• Mass flow meters acceptable, convert to volumetric flow using same equation• Continuous pressure/temperature monitoring systems and engineering calculations

acceptable


Flare Tip Velocity, Vtip - ContinuedCalculation [§63.670 (k)]

• Calculate cumulative flow (Qcum) and Vtip for each 15-min period starting at 12 midnight (i.e., “block”)

𝑽𝑽𝒕𝒕𝒕𝒕𝒕𝒕 =𝑸𝑸𝒄𝒄𝒄𝒄𝒎𝒎

𝑨𝑨𝑨𝑨𝑨𝑨𝒎𝒎 × 𝟗𝟗𝟏𝟏𝟏𝟏• Design and engineering principles to determine unobstructed cross

sectional area

• Qcum only required to include flow during period of regulated material flow

• Direct compositional or net heating value monitoring used to determine NHVvg for Vmax method


Determining Cumulative Flare FlowsQcum, Qvg, Qs, Qa,premix, Qa,perimeter

*Can divide each block into equal subperiods instead of performing calculation for entire 15-min period

Monitoring strategy How to calculate cumulative flow, Q Gas composition data required

Continuous volumetric flow monitoring

Sum P and T corrected volumetric flow data for each 15-min block

Gas composition data not required for flow rate conversion only for determining net heating value

Continuous mass flow monitoring

Mass flow data converted to volumetric flow𝑄𝑄𝑣𝑣𝑣𝑣𝑣𝑣 = 𝑄𝑄𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚

𝑀𝑀𝑀𝑀𝑡𝑡× 385.3

Sum calculated Qvol for each 15-min block

Gas composition data from continuous monitoring or grab sampling every 8-hrs

Continuous P and T monitoring with engineering calculations

Calculate average P and T for each 15-min block*Use calculated average P and T as input parameters for each 15-min block flow calculation*

Gas composition data from continuous monitoring or grab sampling every 8-hrs may be required if part of engineering calculation


Net Heating Value Flare Combustion Zone Gas, NHVczRequirement/Deviation [§63.670 (e)]

• NHVcz at or above 270 British thermal units per standard cubic foot (Btu/scf)

Monitoring [§63.670 (j)]

• Determine concentration of individual components in flare vent gas by• Continuous measurement (at least once every 15-min)• Evacuated canister grab sampling and subsequent analysis at least every 8-hrs• Calorimeter capable of continuous monitoring of vent gas net heating value

(NHVvg) at standard conditions – with or without continuous hydrogen monitoring


Net Heating Value Flare Combustion Zone Gas, NHVcz - Continued

NHVvg Calculation [§63.670 (l)]

• Calculate 15-min block averages for set 15-min blocks starting at 12 midnight using:1. Feed-forward calculation method

2. Direct calculation method

• Use grab sample analytical results from 15-min block when sample was collected to the 15-min block prior to block when subsequent sample is collected

• Can use different calculation methods for different flares

• Elect one calculation method for all vent streams associated with a single flare• 15-minute block average net heating value shall be determined separately for each measurement location and

cumulative NHVvg is flow-weighted average

• Notify Administrator of calculation method changes 30-days prior


Net Heating Value Flare Combustion Zone Gas, NHVcz - Continued

Flares that • Use feed-forward calculation

methodology

• Monitor gas composition or net heating value in a location representative of the cumulative vent gas stream, and

• Directly monitor supplemental natural gas flow additions

𝑵𝑵𝑵𝑵𝑽𝑽𝒄𝒄𝒄𝒄 =𝑸𝑸𝒗𝒗𝑳𝑳 − 𝑸𝑸𝑵𝑵𝑵𝑵𝟐𝟐 + 𝑸𝑸𝑵𝑵𝑵𝑵𝟏𝟏 𝑵𝑵𝑵𝑵𝑽𝑽𝒗𝒗𝑳𝑳 + 𝑸𝑸𝑵𝑵𝑵𝑵𝟐𝟐 − 𝑸𝑸𝑵𝑵𝑵𝑵𝟏𝟏 𝑵𝑵𝑵𝑵𝑽𝑽𝑵𝑵𝑵𝑵

𝑸𝑸𝒗𝒗𝑳𝑳 + 𝑸𝑸𝒎𝒎 + 𝑸𝑸𝒎𝒎,𝒕𝒕𝑨𝑨𝑨𝑨𝒎𝒎𝒕𝒕𝒎𝒎

NHVcz Calculation [§63.670 (m)]

• Other flares, use calculated 15-min block cumulative values for flow (vent gas, steam and premix air) and 15-min block average for NHVvg

𝑵𝑵𝑵𝑵𝑽𝑽𝒄𝒄𝒄𝒄 =𝑸𝑸𝒗𝒗𝑳𝑳 × 𝑵𝑵𝑵𝑵𝑽𝑽𝒗𝒗𝑳𝑳

𝑸𝑸𝒗𝒗𝑳𝑳 + 𝑸𝑸𝒎𝒎 + 𝑸𝑸𝒎𝒎,𝒕𝒕𝑨𝑨𝑨𝑨𝒎𝒎𝒕𝒕𝒎𝒎

NHVcz = NHVvg when there is not assist steam or

premix air


Net Heating Value Dilution Parameter, NHVdil

Requirement/Deviation [§63.670 (f)]• NHVdil at or above 22 British thermal units per square feet (Btu/ft2)

• Flares with perimeter assist air

• Do not calculate for 15-min blocks with no perimeter assist air

Monitoring• Nothing additional to parameter monitoring for Vtip and NHVcz compliance


Net Heating Value Dilution Parameter, NHVdilContinuedNHVdil Calculation [§63.670 (n)]

• Flares that • Use feed-forward calculation methodology

• Monitor gas composition or net heating value in a location representative of the cumulative vent gas stream, and

• Directly monitor supplemental natural gas flow additions

𝑵𝑵𝑵𝑵𝑽𝑽𝒅𝒅𝒕𝒕𝒗𝒗 =𝑸𝑸𝒗𝒗𝑳𝑳 − 𝑸𝑸𝑵𝑵𝑵𝑵𝟐𝟐 + 𝑸𝑸𝑵𝑵𝑵𝑵𝟏𝟏 𝑵𝑵𝑵𝑵𝑽𝑽𝒗𝒗𝑳𝑳 + 𝑸𝑸𝑵𝑵𝑵𝑵𝟐𝟐 − 𝑸𝑸𝑵𝑵𝑵𝑵𝟏𝟏 𝑵𝑵𝑵𝑵𝑽𝑽𝑵𝑵𝑵𝑵 × 𝑫𝑫𝒕𝒕𝒎𝒎𝒎𝒎

𝑸𝑸𝒗𝒗𝑳𝑳 + 𝑸𝑸𝒎𝒎 + 𝑸𝑸𝒎𝒎,𝒕𝒕𝑨𝑨𝑨𝑨𝒎𝒎𝒕𝒕𝒎𝒎 + 𝑸𝑸𝒎𝒎,𝒕𝒕𝑨𝑨𝑨𝑨𝒕𝒕𝒎𝒎𝑨𝑨𝒕𝒕𝑨𝑨𝑨𝑨

• Other flares, use calculated 15-min block cumulative values for flow (vent gas, steam and premix air) and 15-min block average for NHVvg

𝑵𝑵𝑵𝑵𝑽𝑽𝒅𝒅𝒕𝒕𝒗𝒗 =𝑸𝑸𝒗𝒗𝑳𝑳 × 𝑵𝑵𝑵𝑵𝑽𝑽𝒗𝒗𝑳𝑳 × 𝑫𝑫𝒕𝒕𝒎𝒎𝒎𝒎

𝑸𝑸𝒗𝒗𝑳𝑳 + 𝑸𝑸𝒎𝒎 + 𝑸𝑸𝒎𝒎,𝒕𝒕𝑨𝑨𝑨𝑨𝒎𝒎𝒕𝒕𝒎𝒎 + 𝑸𝑸𝒎𝒎,𝒕𝒕𝑨𝑨𝑨𝑨𝒕𝒕𝒎𝒎𝑨𝑨𝒕𝒕𝑨𝑨𝑨𝑨


Implementation Summary• Determine flare design parameters – smokeless capacity and unobstructed area

• Flare vent gas flow meter likely in place for NSPS Subpart Ja compliance

• Assist steam or assist air flow meter – may require installation of additional instrumentation

• Determine compositional monitoring strategy that best fits – gas chromatograph, 8-hr grab sampling, or calorimeter

• Sulfur monitoring device likely in place for NSPS Subpart Ja compliance, may need additional instrumentation to get composition of other constituents

• Evaluate how to reduce collected data for comparison with regulatory limits


Stephen WallsAir Permitting Engineer

[email protected]

mailto:[email protected]

Refinery Flares

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