Flare Radiation Analysis
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FLARE RADIATION Analysis Flare System Design
Transcript of Flare Radiation Analysis
FLARE RADIATIONAnalysis y
Flare System Design
Flare RadiationFlare Radiation
depends on fraction of heat radiated from the flame
• Gas composition• Flame type
St t f i f l i i• State of air-fuel mixing• Soot/smoke formation• Quantity of fuel being burned• Quantity of fuel being burned• Flame temperature• Flare burner design
Flare System Design
Flare burner design
Flare Radiation basic calculationFlare Radiation basic calculation
Q Heat release KWRadiant Epicentre
Q Heat release KWF fraction of heat radiatedD distance to pointK radiant heat flux kw/m2
DReceptor point perpendicular to D
K radiant heat flux kw/m
D perpendicular to D
K= FQ/4πD2HK= FQ/4πD
Vary H to meet radiation limit
Flare System Design
Fraction of heat radiated f factorFraction of heat radiated f factor
Many different methods for predictingMany different methods for predictingYear Author
1964 Kent1967 Tan1969 API single point1973 Brzustowski and Sommer1973 Brzustowski and Sommer1979 Leahey et al.1980 Oenbring and Sifferman1981 B k d L i1981 Becker and Laing 1984 Leahey and Davies1987 Cook et al.
Flare System Design
1987 Chamberlain
Flare Radiation basic calculationFlare Radiation basic calculation
Computer software now allows d t il d l l tidetailed calculations ;
• multipoint analysis
D
• Τ transmissivity (humidity)
• Ø angle of incidence for inclinedreceptor pointsD p p
• ε receptor emissivity
• shieldingH
• view angle
• temperature calculations
H
Flare System Design
Ø
Flare Radiation view angleFlare Radiation view angle
Partial view
Partial view
stack
store
Flare System Design
Flare Radiation view angleFlare Radiation view angle
Roof sees entire flame
stack
store
Flare System Design
Radiation Recommended LimitsRadiation – Recommended Limits Radiation
LevelRadiation
LevelTemp Above
ambient Duration
w/m2 btu/ft2 C
1270 400 12 Helicopter decks0 00 e copte dec sno rotors
1900 600 19 acceptable
3100 1000 31 U f bl f3100 1000 31 Uncomfortable for long periods
4730 1500 46 Several minutes
6300 2000 61 30-60 seconds
9460 3000 89 Few seconds only t t t
Flare System Design
must retreat
Radiation Isopleths sizing the stackRadiation Isopleths - sizing the stack
Flare System Design
Radiation Isopleths FlaresimRadiation Isopleths - Flaresim
Can also calculate similar plots for temperatures and
Flare System Design
temperatures and noise levels
Meeting Flare Radiation Limits
Increase length of flare boom
Meeting Flare Radiation Limits
Increase length of flare boom
Increase height of flarestack
Provide radiation shielding
Provide water spraysp y
Reduce flaring rate
Use high velocity tips
Flare System Design
Flare ShieldingFlare Shielding
Plan View with shielding
Flare System Design
Water CurtainsWater Curtains
high pressure atomised water is sprayed behind thehigh pressure atomised water is sprayed behind the burners to absorb upto 70% of the incident radiation
Flare System Design
Water CurtainsWater Curtains
Too much water ?
M i li ht
Flare System Design
May require a relight…… …
Radiation Sonic vs PipeflareRadiation Sonic vs Pipeflare
Up to 5 times as muchUp to 5 times as much radiation from a pipeflare
Radiationlevel Sonic PIPEFLARE
Flare System Design
Distance along boom
Radiation Red cing Flare RateRadiation Reducing Flare Rate
Scenario Flow
Power failure 258000 => flare design flowCooling Water failure 220000 85% design flowCooling Water failure 220000 85% design flowFire Zone 1 125000 48%Fire Zone 2 45000 17%Fire Zone 3 98000 38%Depressuring Zone 1 245000 95%Depressuring Zone 2 6500 3%p g
Probably very little reduction possible.
Flare System Design
Radiation Red cing Flare RateRadiation Reducing Flare Rate
Scenario Flow
Depressuring Zone 1 445000 => flare design flowPower failure 258000 58% of designPower failure 258000 58% of designCooling Water failure 220000 49% Fire Zone 1 125000 28%Fire Zone 2 45000 10%Fire Zone 3 98000 22%Depressuring Zone 2 6500 1.5%p g
DP of Zone 1 is by far the highest flow reducing this will result in a smaller flare system, saving $$$$$$
Flare System Design
smaller flare system, saving $$$$$$
Summary on Radiation Limits
Evaluate the radiation levels expected and
Summary on Radiation Limits
Evaluate the radiation levels expected and
reduce stack size by ..
provide radiation shielding where needed
Provide water sprays
Review relief loads and reduce flaring rate
U hi h l it ti if iblUse high velocity tips if possible.
Flare System Design
