Flames with flare and momentum - hazards to offshore platform boom structures and potential mitigation

Flam es with Flare and Momentum - Hazards to O ffshore Platform B oom Structures and Potential Mitigation E .W . ( T e d ) G r a n d m a i s o n C h e m ic a l E n g in e e rin g Q u e e n ’s U n i v e r s i t y IF R F T O T e M 3 6 P erson n el Dr. Paulo Pagot, Senior Consultant, PETROBRAS Petroleo Brasileiro S.A. CENPES/ PDP/ MC P erson n el Andrezj Sobiesiak, Mechanical & Materials Engineering, University of Windsor David Poirier, Chemical Engineering, Queen’s University Offshore flare systems: P la tf o r m - b a s e d fla re b o o m Floating Production Storage and Offloading (FPSO) ship P la t f o r m s a r e i s o l a t e d ... c o n c e r n s • Platform stability with flaring hardware • Thermal radiation exposure for the workplace • Combustion noise for the workplace F la re b o o m s ~ 8 0 - 9 0 m lo n g a n d a n g le d ~ 4 5 o re la tiv e to p la tfo rm T r a d itio n a l i s s u e s ... • Soot, HC em issions ... • Other emissions, e.g. NOx I m p r o p e r o p e r a tio n o f a m u lti-je t fla re w ith lo w je t v e lo c itie s f o r a ll s t a g e s ( p r o b l e m s in t h e s t a g e c o n t r o l v a l v e s ) O th er is s u e s • How to accommodate marginal production increases within other constraints ■ Blowers A s ta c k - e n c lo s e d g a s fla r in g s y s te m S c h e m a tic d ia g r a m o f th e r a d ia tio n Singhal, S.N1., Delichatsios, M.A.2 and de Ris, J.2, Fire Safety Journal, "Offshore Stackenclosed Gas Flares: Part I - Theoretical Development”, 15, 211-225 (1989); "Offshore Stack-enclosed Gas Flares: Part II - Applications and Results”, 15, 227-244 (1989). 1 Amoco Production Company, Tulsa, OK 2 Factory Mutual Research Corporation, Norwood, MA p r o b le m S t a n d a r d s fo r r a d ia tio n l e v e l s P e r m is s ib le d e s ig n le v e l C o n d itio n s k W / m 2 ( B T ll / h - f t 2) M a x im u m r a d ia n t h e a t in te n s ity in a r e a s w h e r e e m e r g e n c y a c tio n s la s tin g 2 m in to 4 .7 3 (1 ,5 0 0 ) 3 m in c a n b e r e q u ir e d b y p e r s o n n e l w it h o u t s h ie ld in g b u t w ith a p p r o p r ia te c lo th in g * . M a x im u m r a d ia n t h e a t in te n s ity a t a n y lo c a tio n w h e r e p e r s o n n e l w ith a p p r o p r ia te 1 .5 8 ( 5 0 0 ) c lo t h in g * c a n b e c o n tin u o u s ly e x p o s e d . * Appropriate clothing consists of hard hat, long-sleeved shirts with cuffs buttoned, work gloves, long-legged pants and work shoes. Appropriate clothing minimizes direct skin exposure to thermal radiation. A N S I / A P I S t a n d a r d 5 2 1 / I S O 2 3 2 5 1 , “P r e s s u r e - r e l i e v i n g a n d D e p r e s s u r i n g S y s t e m s ”, T a b l e 9 , p a g e 7 8 , 5 th E d i t i o n , J a n u a r y 2 0 0 7 . Flare burner geometries (boom mounted) 16.4 m 20.0 m R e c ta n g u la r b u rn e r a lig n m e n t T o t a l o f 4 1 b u r n e r s s h o w n in e a c h a l i g n m e n t F la r e b u r n e r m o d e l: G as S u p p ly D i m e n s i o n s in m m N ozzle fittings (static) C o n e s a tta c h m e n ts: P r e c e s s in g je ts: R in g a tta c h m e n ts : Induced A ir A P re c e s s in g je t A C o n e a tta c h m e n ts E x p e r im e n ta l P r o g r a m C o ld M o d el T e s ts • • • W in d tu n n e l t e s ti n g fo r t h e m u lti­ H ot M odel T e s ts • M u lti-je t f la re m o d e l p e r f o r m a n c e j e t f l a r e m o d e l in a c r o s s f l o w f i r i n g n a t u r a l g a s in a c o n t r o l l e d L a s e r s h e e t i l l u m i n a t i o n in c r o s s w in d d iffe re n t p l a n e s to p ro v id e • P h o to g ra p h ic a n d C C D im a g in g q u a lita tiv e flo w b e h a v i o u r • G a s te m p e ra tu re m e a s u re m e n ts L a s e r lig h t-s c a tte r t e c h n i q u e s to p ro v id e q u a n tita tiv e in fo rm a tio n a lo n g th e fla m e tra je c to ry • ( j e t flu id c o n c e n t r a t i o n f ie ld ) S p e c ie s c o n c e n tra tio n m e a s u r e m e n ts a lo n g th e fla m e tra je c to ry • R a d ia tio n m e a s u r e m e n ts for a s in g le s id e -v ie w fix e d p o sitio n . The jet in a cross-flow (isothermal) J e t tra je c to ry : 1 = f d: E n tra in m e n t: d \ r p j V 2 r dm = 2 u _ 0 .0 8 V Pc° j V Jet entrainment effect B r z u s t o w s k i ( 1 9 7 7 ) - a is a p a r a m e t e r r e l a t e d to t h e c r o s s f lo w c o n d i t i o n s u j u Cross flow effect Brzustowski, T. A. - Hydrocarbon Turbulent Diffusion Flame m Subsomc Cross f |ow Turbulent Combustion - v.58 (Progress in Astronautics and Aeronautics), pp. 407-430, 1977 C o o r d in a te s y s t e m A z Cross flow x Burner model y Cold model test program: 3480 1220 1372 4115 W o rk in g s e c t i o n d etail D i m e n s i o n s in m m C ross flo w 457 n 87 1 500 C r o s s flo w v e lo c ity u M = 2 .8 m /s P jw j2 /P „ u ^ 2 = 5 5 7 J e t n o z z le v e lo c ity w = 6 8 .7 m /s Cold model studies Z x -z p la n e A cross flow Origin at first nozzle center Arm Top X Burner Model S h e e t illu m in a tio n a n d q u a n t i t a t i v e j e t flu id c o n c e n tra tio n m e a s u r e m e n ts S h e e t illu m in a tio n R eferen ce c a se C o n e a tta c h m e n ts R in g a tta c h m e n ts Cold model showing jet/cross-flow interaction PjU,2/p.U„2 = 557 z, m m z , mm x, m m J e t flu id s c a l a r c o n c e n t r a t i o n p r o f i le s - x, m m m id -w a y b e tw e e n je ts 120 100 - • ■ o □ C o n e a tta ch m en ts ▲ A P r e c e ssin g n o z z le s ♦ o R in g a tta c h m e n t s R eferen ce c a s e P a trick ( 1 9 6 7 ) 80 - j 60 - 40 - z /d 20 0 0 20 40 60 80 100 120 x /d j J e t p e n e tra tio n R e f e r e n c e c a s e & R in g a tt a c h m e n t s > C o n e a t t a c h m e n t s & P r e c e s s i n g n o z z le s z i X -Y p l a n e a t z = 4 0 . 3 m m o r z /d j = 1 3 . 4 R eferen ce c a se P re c e s s in g je ts R in g a tt a c h m e n t s Y -Z p la n e a t th e c e n tr e o f th e m a n ifo ld P re c e s s in g je ts R in g a tt a c h m e n t s H o w d o m u ltip le je ts in c r o s s - f l o w in tera ct? (b) T rip le j e t s y s t e m a t (a ) M = 3 .5 , (b) M = 5 .2 5 , (c) (c) M = 7 a t s /D o = 6 . H ot m o d el te sts: Fence grass grass n-* ----- Removable Screen (black/grid) Gas Line 01" Open Wind Tunnel Burner Blower A Fan stack Shed h Blower B i\rv n' Traverse Mechanism concrete pad Gas Control Station Fence Radiometer C AG CT Laboratory Building -i Door gravel -X 800 C r o s s f lo w air s u p p l y y 1000 150 N a tu ra l g a s s u p p ly H o t m o d e l t e s t c o n d itio n s : N o z z le F la rin g C r o s s f lo w C o n d itio n s C o n d itio n s C o n d itio n s m f, H eat U, k g /h re le a se , kW m /s 1 6 ,8 0 0 3 5 .8 523 3 .9 261 7 0 .9 1 5 ,1 0 0 3 2 .3 471 3 .9 213 C 5 5 .0 1 1 ,7 0 0 2 5 .0 3 8 4 3 .9 128 D 3 9 .3 8 ,4 0 0 1 7 .9 268 3 .9 6 5 .4 E 1 7 .8 3 ,8 0 0 8 .1 140 3 .9 1 3 .4 T e st Uf, C o n d itio n s m /s A 7 8 .5 B NRe P f U f W Hot model pictures I - flow condition A, 523 kW Cone attachments Hot model pictures II - flow condition A, 523 kW Side view Precessingjets Ring attachments F r o n t v ie w CCD black &white time-averaged imaging - reference case, flow condition A,100s time average 1200 1000 800 B & W image | 600 N 400 200 0 •400 -200 0 200 400 600 800 1000 1200 X (mm) -600 -600 -400 -200 0 Y(mm) 200 400 600 800 1200 1000 50% intermittency ^ 800 £ 600 N 400 200 0 -200 -400 0 400 800 1200 -8 0 0 -4 0 0 0 400 x, m m y, m m S id e v ie w F ro n t v ie w 800 - cone attachments, flow condition A, 100 s time average B & W image 50% intermittency -400 0 400 x, m m 800 1200 y, m m Hot model flame structure Zone 2 Zone 1 v • Zone 1 - individual flame and cross-flow interaction Zone 2 - buoyant region with merged jets forming a plume O □ A v O 800 — T ra je c to ry d e p e n d s on: 600 1 A B C D E i i i i & © <EV (07 “ 200 - & & ° - d e p e n d e n t) ey 0 • c ro ss-flo w 1 m o m e n tu m -200 flu x 1000 1 o _£> Reference case 1 1 1 1 1 i _ 0 200 400 1 1 i A □ B AC v D • n o z z le c o n fig u ra tio n 600 fro n t v ie w a r e a □ p r o je c te d to th e c r o s s ­ □ - N □ 400 q¥ flo w ° o □ * O A V A 10 o □ 8 V A 0 Q s Q Q) -a Cone attachments j ___ i___ i___ i___ i___ f| - _ o _L -200 0 200 400 600 800 1000 i----- 1----- r o □ CD o A □ B A C V D o E Cd A Ct|A ctA A ° AV ° □ AV cF 200 1 o □ E • 1 □ □ £ 800 > o 800 _ 600 □ O vA “ 400 “ N o A □ B A C V D _ © v • b u o y a n c y (firin g r a t e ______________________________________________________________________ L 1000 V V ° O Ct3%0 ° o o Q£' 0 1 -200 1 i i 0 200 Precessing jets i i i 400 600 x, c m 800 | Ring attachments j ___ i___ i___ i___ i___ 1000 -200 0 200 400 x, c m 600 800 1000 Ring attachments z, m m Reference case x, m m x, m m Side view flare shape at different heat release rates Gas temperature along the flare flame trajectory Flow condition A (523 kW) CD 0 .0 0 .2 0 .4 0 .6 0 .8 1 .0 Gas composition along the flare flame trajectory Flow condition A (523 kW) O 2 , mole % 20 • □ A V 16 T T Reference Cone attachments Precessing jets Ring attachments v 12 8 v« V _ ■ V 4 8 v.V el 6 o m A V% VV V _ v # V y V B V V tL V O , C % C H 4 , mole V '• 4 V V ^7 \ • V v • ^7V & 7V mm 0 • □ A v - 80 T T Reference Cone attachments Precessing jets Ring attachments d d A v • □ A v 60 A - m V V* V 40 O - K7 T T Reference Cone attachments Precessing jets Ring attachments V X r e z A 2 v 2 8 4 w v 0 6 T T • Reference □ Cone attachments A Precessing jets V Ring attachments 20 ■A I V v • •*! 0 0 .0 0.2 0.4 0 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 400 200 ra d ia tiv e 0 400 T o ta l heat flu x , W / m 2 600 200 600 0 0 200 400 F la re 600 firin g 0 ra te , 200 400 kW Radiative heat flux as a function of firing rate 600 C o n c lu d in g re m a rk s • Cold model studies showed that static fixtures could alter the mixing behaviour of the multi-jet flare system. Precessing jets and cone attachments showed broader transverse mixing and less penetration into the cross­ flow. • Hot model studies revealed two flow regimes - a flame/cross-flow interaction region, followed by a buoyancy dominated region. • The static fixtures led to more complex behaviour in terms of flare trajectory, gas temperature, gas composition and flame radiation.