Col umnPi pi ng:St udyLa y out ,Noz z l eOr i ent at i on&Pl at f or ms Re qu i r e me me nt s s
1. 0SequenceofCol umn mnPi pi ngSt udy 1 . 1 Al l a v ai l a bl ei nf or ma t i o n/da t af r om Eq ui p me me nts pe ci fi c at i o na ndP&I Ds ha l l b ewr i t t eno nt hee l e v at i onv i e w oft h ec ol umn asi l l us t r a t e di nFi g. 1 ,2& 3 . 1 . 2 Thede si g nern ows t a r t st h i n ki ngabo utt h epr o per or i ent at i onofnoz zl es andpr o vi s i onsf orac ces st ot hepoi nt sof o pe r a t i o na ndma ma i n t e na nc e . 1 . 3 Co ns i d er a t i on soft hepi pel i ne l ea vi ngt het owerar eaandt headj ac entpi pi ngshal l bevi s ual i z ed. 1. 4 Thefir s ts t epi st oor i entt hema manhol espr ef er abl yal l i nsamedi r ec t i ons .Nor mal l y ,manhol e ss hal l beor i ent edt owar ds d r o pou ta r e awi t h i na3 0°s e gmen to fc o l umna st h i sf ac i l i t a t est h el o wer i n go ft o we ri n t e r n al st ot hema i na cc es swa y .Th e ma nh ol es eg me me nto fp l a t f o r ms h ou l dn o tb eo c c up i e db yan ypi p er a c k . 1 . 5 Ab r e aki nl a dd err i s e( n or ma l5 m,ma m, x i mu m7 m)wi m) l l o c cu pya no t h ers e gme nto fc o l u mnf mn o rp l a t f o r m. 1 . 6 Thel e v el sofpl a t f or msa r et obedec i d edont h ee l e v at i o nv i e w ba sedont h ema nh ol e san da cc es st or e l i e fv al v es , i ns t r umentf orv i e wi ng. 1 . 7 Al l p l at f or ml e v el si nt h epr o pe rs egme nt so ft het o werwi t hl ad de rl o cat i ons ho ul dbedr a wnonpl anv i e w.Thema man ho l e s ha l l b es ho wni npr o pe rs e gmen twi t ht h ea ng l eo for i e nt a t i o n,an dt h es pac ef ort h es wi ngofman ho l ec o ve rt a ki ngda v i th i n ge a scen t r e. 1 . 8L ay o uts ho ul dbest a r t e df r o mt h et o poft h ec ol umnwi t ht hed es i gn erv i s ua l i z i n gt hel a y ou ta sawho l e.Th er ewi l l b en o d i ffic ul t yi ndr o pp i n gl ar g eo v er he adl i n es t r a i g htdo wnt h es i deofaco l u mn mn ,a ndl ea v est h ec ol u mnatah mn i ghl e v el an dc r o ss es di r ec t l yt ot hec ondens er .Thi scl ear sas egmentatl o werel ev at i onsf orpi pi ngorf oral adderf r om gr adel e vel t ot hefi r s t pl at f or m.
1. 9 Fl e xi bi l i t yandt her mal l oadc onnec t edwi t ht hel ar gedi aov er headl i nest ot hec ondens eratgr adel ev el orhi gherl e vel s hal l bec ons i der ed.Ther el i efv al v epr o t ec t i ngt het oweri sus ual l yc onnec t edt ot heov er headl i ne.Ar el i efv al v edi s c har gi ngt o a t mo s ph er es h ou l db el o ca t e do nt h eh i g he s tt o we rp l a t f o r m. I nac l os edr el i ef l i nes y st em,t her el i ef v al v es houl dbel o cat edont hel owes tt owerpl at f or m abo vet her el i efs y st em header . Thi swi l l r es ul ti nt hes hor t es tr el i ef v al v edi s char gel eadst ot hefl ar eheader .Theent i r er el i ef l i nes ys t em s houl dbes el f dr ai ni ng. 1. 10 Fr om l a youtpoi ntofv i ew,i ti spr ef er abl et ospac et hepl at f or m br ac k et sont het owerequal l yandt oal i gnt hebr ac k et s o vereac hot herf ort heent i r el engt hoft het ower .Thi swi l l mi ni mi z ei nt er f er enc esbe t weenpi pi ngandst r uc t ur al member s . 1 . 1 1 No z zl e san dp i p i n gmu s tme etp r o ce s sr e qu i r e me me nt swh i l epl a t f o r msmu mu s ts a t i s f yma ma i n t e na nc ean do pe r a t i n gn ee ds . Ac c es sf o rt o werpi p i ng ,v al v e san di n st r ume nt si n flue nc ep l ac eme ntofl a dd er s . 1. 12 I nr out i ngpi pel i nes ,t hepr obl em i sf ac edt oi nt er c onnec t edt owernoz z l eswi t hot herr emo t epo i nt s .Thet ent at i v e or i ent at i onofagi v ent owernoz z l ei sont hel i nebe t weent owerc ent r eandt hepoi ntt owhi c ht hel i nei ss uppos edt or u n. Se gme nt sf orp i pi n gg oi n gt oequ i pmen ta tgr a dee. g .c on den seran dr eb oi l e rl i ne sar eav ai l a bl ebe t we enl a dd er san db ot h s i d esofma nh ol e . Seet heF eFi g. 4/5f oro ver al l or i ent at i onofadi s t i l l at i onc ol umn. Li neappr oac hi ngt hey ar d/ pi per ac kcant ur nl ef torr i ghtdependi ngont heov er al l ar r angementoft hepl ant .Ther e s pec t i v e s e gme nt soft h es el i n esar eb et we ent h el a dd er san d1 80 ° .Th es e gme nta t1 80 °i sc on v en i e ntf o rl i n eswi t h ou tv a l v e sa nd i ns t r ument s ,bec aus et hi si st hepoi ntf ar t hes tf r om manhol epl at f or ms . Th es equ en ceo fl i n esar ou ndt h et o weri si n flue nc edb yc ond i t i o nsatgr a del e v el .Pi p i n ga r r an ge me me nt swi t ho utl i n esc r o ss i n g o v ere ac hot he rg i v ean eatap pea r a nc ea ndus ua l l yamo mor ec on v en i en ti n st a l l a t i on . 1 . 1 3 Th ec or r e ctr el at i o ns hi pbe t we enp r o c es snoz z l e sa ndt o weri nt e r n al si sv er yi mp or t a nt .Ana ng l ei sus ua l l yc ho se n bet weent her a di al c ent r el i neofi nt er nal sandt ower s hel l c ent r el i nes . Bypr o perc ho i c eoft hi san gl e( us ual l y45 °o r9 0°t ot h ep i pe r a c k )ma nyh ou r so fwor ka ndf ut u r ei nc on v eni e nc ecanbes av ed . T owerpi pi ng,s i mpl i c i t yofi nt er nal pi p i ngandmanhol esac c es si nt ot het owerar eaff ec t edb yt hi sangl e.Af t ert hi s ,t he i nf or mat i onpr oduc edb yt hedes i gnerr es ul t si ns el ec t i ngt hec or r ec tor i ent at i onoft owerno zz l es . 1. 14 Ada vi tus ua l l yhandl eshea vyequi pments uc hasl ar ges i z er el i efv al v esandl ar gedi ame t erbl i nds .I ft heda vi ti satt he t opoft het ower ,i tc anal s os er v ef orl i f t i ngandl ower i ngt oweri nt er nal st ogr ade. Cl ear anc ef ort hel i f t i ngt ac k l et oal l poi nt sf r om whi c hha ndl i ngi sr equi r ed,andgoodac ces sshoul dbepr o vi ded.
1. 9 Fl e xi bi l i t yandt her mal l oadc onnec t edwi t ht hel ar gedi aov er headl i nest ot hec ondens eratgr adel ev el orhi gherl e vel s hal l bec ons i der ed.Ther el i efv al v epr o t ec t i ngt het oweri sus ual l yc onnec t edt ot heov er headl i ne.Ar el i efv al v edi s c har gi ngt o a t mo s ph er es h ou l db el o ca t e do nt h eh i g he s tt o we rp l a t f o r m. I nac l os edr el i ef l i nes y st em,t her el i ef v al v es houl dbel o cat edont hel owes tt owerpl at f or m abo vet her el i efs y st em header . Thi swi l l r es ul ti nt hes hor t es tr el i ef v al v edi s char gel eadst ot hefl ar eheader .Theent i r er el i ef l i nes ys t em s houl dbes el f dr ai ni ng. 1. 10 Fr om l a youtpoi ntofv i ew,i ti spr ef er abl et ospac et hepl at f or m br ac k et sont het owerequal l yandt oal i gnt hebr ac k et s o vereac hot herf ort heent i r el engt hoft het ower .Thi swi l l mi ni mi z ei nt er f er enc esbe t weenpi pi ngandst r uc t ur al member s . 1 . 1 1 No z zl e san dp i p i n gmu s tme etp r o ce s sr e qu i r e me me nt swh i l epl a t f o r msmu mu s ts a t i s f yma ma i n t e na nc ean do pe r a t i n gn ee ds . Ac c es sf o rt o werpi p i ng ,v al v e san di n st r ume nt si n flue nc ep l ac eme ntofl a dd er s . 1. 12 I nr out i ngpi pel i nes ,t hepr obl em i sf ac edt oi nt er c onnec t edt owernoz z l eswi t hot herr emo t epo i nt s .Thet ent at i v e or i ent at i onofagi v ent owernoz z l ei sont hel i nebe t weent owerc ent r eandt hepoi ntt owhi c ht hel i nei ss uppos edt or u n. Se gme nt sf orp i pi n gg oi n gt oequ i pmen ta tgr a dee. g .c on den seran dr eb oi l e rl i ne sar eav ai l a bl ebe t we enl a dd er san db ot h s i d esofma nh ol e . Seet heF eFi g. 4/5f oro ver al l or i ent at i onofadi s t i l l at i onc ol umn. Li neappr oac hi ngt hey ar d/ pi per ac kcant ur nl ef torr i ghtdependi ngont heov er al l ar r angementoft hepl ant .Ther e s pec t i v e s e gme nt soft h es el i n esar eb et we ent h el a dd er san d1 80 ° .Th es e gme nta t1 80 °i sc on v en i e ntf o rl i n eswi t h ou tv a l v e sa nd i ns t r ument s ,bec aus et hi si st hepoi ntf ar t hes tf r om manhol epl at f or ms . Th es equ en ceo fl i n esar ou ndt h et o weri si n flue nc edb yc ond i t i o nsatgr a del e v el .Pi p i n ga r r an ge me me nt swi t ho utl i n esc r o ss i n g o v ere ac hot he rg i v ean eatap pea r a nc ea ndus ua l l yamo mor ec on v en i en ti n st a l l a t i on . 1 . 1 3 Th ec or r e ctr el at i o ns hi pbe t we enp r o c es snoz z l e sa ndt o weri nt e r n al si sv er yi mp or t a nt .Ana ng l ei sus ua l l yc ho se n bet weent her a di al c ent r el i neofi nt er nal sandt ower s hel l c ent r el i nes . Bypr o perc ho i c eoft hi san gl e( us ual l y45 °o r9 0°t ot h ep i pe r a c k )ma nyh ou r so fwor ka ndf ut u r ei nc on v eni e nc ecanbes av ed . T owerpi pi ng,s i mpl i c i t yofi nt er nal pi p i ngandmanhol esac c es si nt ot het owerar eaff ec t edb yt hi sangl e.Af t ert hi s ,t he i nf or mat i onpr oduc edb yt hedes i gnerr es ul t si ns el ec t i ngt hec or r ec tor i ent at i onoft owerno zz l es . 1. 14 Ada vi tus ua l l yhandl eshea vyequi pments uc hasl ar ges i z er el i efv al v esandl ar gedi ame t erbl i nds .I ft heda vi ti satt he t opoft het ower ,i tc anal s os er v ef orl i f t i ngandl ower i ngt oweri nt er nal st ogr ade. Cl ear anc ef ort hel i f t i ngt ac k l et oal l poi nt sf r om whi c hha ndl i ngi sr equi r ed,andgoodac ces sshoul dbepr o vi ded.
1. 15 Ver yof t en,i nt er pr e t at i onofpr oc es sr e qui r ement si ns i deat oweri smo mor ee xac tt hanf ore xt er i orpi pi ngde si gn.The l oc at i onofani nt er nal par tdet er mi nes ,wi t hi ns t r i c tp hy si c al l i mi t s ,t hel oc at i onoft owern oz zl es ,i ns t r ument s ,p i pi ngandt he s t e el wor k .Th el a y ou td es i g nerh ast oc on cen t r at eonal a r g es c al edr a wi n go ft o we r i n t e r n al de t a i l sandar r a ng eme ntof pr oc es spi pi ngt ofi nal i z et hep i pi ngs t udy . 1. 16 Ac ces s ,whet heri nt er nal ore xt er nal i sv er yi mpor t ant .Thi si nc l udesac ces si bi l i t yofc onnec t i onsf r om l adder sand p l at f o r msandi nt e r n al a cc es s i b i l i t yt hr ou ghsh el l ma nh ol e s,h an dh ol e sorr e mo mo v ab l ese ct i o nsoft r a y s.Ama nh ol eop en i ngmu mu st notbeobs t r uc t edb yi nt er nal pi pi ng. 1 . 1 7 Re bo i l e r l i n ee l e v at i on sar ede t e r mi ne db yt hed r a wo ffa ndr e t u r nno zz l e sa ndt h ei ror i e nt a t i o ni si n flu en cedb yt h er ma l fl ex i bi l i t yc ons i der at i ons .Reboi l erl i nesandt heo ver headl i nesshoul dbeassi mpl eanddi r ec taspos s i bl e. 1 . 1 8 Fi s ho wst h es eg me me nt soft o werc i r c umf er en ceal l o t t edt opi p i ng ,n oz z l es ,ma nh ol e s,p l at f or m br ac k et san dl a dde r sa s g. 6 n or ma l l yr e co mme mm nd edt ode v el o pawe l l d es i g ne dl a y ou t .
2 . 0 Noz z l eOr i e nt a t i ona ndLe v el Noz z l e sar el o ca t e da tv ar i o usl e v el sont het o we rt ome me ett hepr o ces san di n st r u me me nt a t i o nr e qui r e me me nt s . 2. 1Ma Manhol es
No z zl e sa r et ob eo r i e nt e dk e ep i n gp r o v i s i o nf o rma i n t e na nc ea ndo pe r a t i o nn ee ds . Ma nh ol e sar eus ua l l yl o ca t edatbo t t o m,t m, opan di n t e r me di a t ese ct i o nsoft o wer .Th es ea cc es sno zz l e smus tn otb el o cat e da t t h edo wnc omers ec t i on so ft h et o werort hes ea lpo ts ec t i o nsoft h et o wer . Wher ei nt er nal pi pi ngi sar r angedov erat r ay ,manhol eshal l bepr o vi dedbuti ts houl dbeens ur edt hatt hei nt er nal sdonotbl oc k t h ema ma i n t e na nc ea c c es st h r o ug ht h ema ma nh ol e . Pos si bl el oc at i onofmanhol eandhandhol eswi t hi nt heangul arl i mi t sofb°a r ei l l us t r at edi ndet ai l 2of Fi g. 4
Fi g1-Sa mp mp l ePi p i n ga ndI n s t r u me me nt a t i o nDi a gr a ma r o un daCo l u mn mn
Fi g2Ev a l ua t i o no ft heFl o w Di a gr am f oraDi s t i l l a t i onCo l umnt oVi s ua l i z ea nOr de r l yAr r an ge me nto fPi p i ng
Fi g3 -T y pi c al No zz l eL oc at i onan dPl a t f or m El e v at i o ns
Fi g4-Det ai l sofaT ypi c al Di s t i l l at i onCol umn
Fi g5-T y pi c al T o we rPi p i n gAr r a ng eme nt
Fi g6-T ypi c al T owerAr eaDi v i s i onf orVar i ousFac i l i t i es 2 . 2Re boi l e rCo nn ec t i on s
Rebo i l erc onnec t i onsar en or mal l yl oc at edatt hebo t t om s ec t i onoft het ower .De t ai l 1of Fi g. 4s h owsr e bo i l e rd r a wo ff c onnec t i onsf ors i ngl efl owt r a y .Thi sc onnec t i onc anbever yi mpor t antf orar r angi ngt r a yor i ent at i on.Thes i mpl es t ,mos t ec onomi c al l oc at i onf orr eboi l erc onnec t i onswi t ht heal t er nat i v el oc at i onwi t hi nt heangul arl i mi t sofa°i sshown.Theangl ea° d ep en dsont h es i z eo fr e bo i l e rd r a wo ffn oz z l eandt h ewi dt hoft hebo ot( d i men si on‘ b ’ )att h et r a ydo wnflo w. Th er e t ur nc onn ec t i o nf r o mt h et h er mo sy ph onr eb oi l e r si ss ho wni nde t a i l 1of Fi g. 4. Thes el i ness houl dbeass i mpl eandasdi r ec taspos s i bl e,c ons i s t antwi t ht her e qui r ement soft her mal fl ex i bi l i t y . Forhor i z ont al l ymount edt her mos y phonr eboi l er ,t hedr a w offnoz z l ei sl oc at edj us tbel o wt hebo t t om t r a yandf orv er t i c al l y mo un t e dr e ci r c ul a t i n gt he r mos y ph onr e boi l er ,t h ed r a wo ffn oz z l ei sl oc at e da tt h eb ot t om he ad .Fo rb ot ht h es y s t e ms ,t h er e t u r n noz z l esar el oc at edj us tabo vet hel i qui dl e vel ass ho wni nFi g. 7.
Fi g7–Re bo i l e rCo nn ec t i o n 2. 3RefluxConnect i ons
Refl uxnoz z l esar epr o vi dedwi t hi nt er nal pi pest hatdi s char get hel i qui di nt ot hes eal po to ft het r a ybel o w.De t ai l 3 ofFi g. 4s ho wst h er e flu xc on ne ct i o ns .Ca r emus tbet a k ent ha tt h eh or i z on t a ll egoft h ei nt e r n al p i pec l e ar st h et o psofb ub bl e c ap sorwei r s .I tmu stb ee ns ur edt ha tt hei n t e r n al p i p ec anbef a br i c at edf orea syr e mo v al t h r o ug haman hol eorc anbe f abr i c at edi ns i det het owers hel l . 2. 4Over headConnect i ons
Thev apourout l etnoz z l ei sus ual l yav er t i c al noz z l eont het opheadoft ower .I naddi t i on,t hev entandr el i efv al v ec oul dbe l o ca t edont h et o ph eadwi t hat y pi c al pl at f or ma r r a nge me ntf ora cc es st ov ent ,i n st r u me ntc on ne ct i on sa ndt opma nh ol e.I na c l os edr el i efl i nes y st em,r el i efv al v es houl dbel oc at edont hel owes tt owerp l at f or m abo vet her el i efs y st em header .Thi swi l l r es ul ti nt hes hor t es tr el i efv al v edi s char gel eads .T heent i r er el i efl i nes ys t em s houl dbes el fdr ai ni ng. 2. 5Bot t om Connect i ons
Thel i qui dout l e ti sl oc at edont hebot t om headoft het ower .I ft het oweri ssuppor t edons ki r t ,t henoz zl ei sr o ut edout s i det he s k i r ta ss ho wni nFi g. 8.Th ee l e v at i o na ndo r i en t at i o noft h i sl i n ei sgen er al l ydi c t a t edb yt h ep umpNPSHr eq ui r emen ta ndt he pumps uc t i onl i nefl ex i bi l i t y . ( se eFi g. 9 )
Fi g8-De t ai l sofT owerSk i r t
Fi g9Ne tPo s i t i v eSu c t i o nHe ad( NPSH)o fBo t t o msPu mp 2 . 6Te mp er a t ur e&Pr e s su r eI ns t r u me ntCon ne c t i ons/L ev e lI n st r ume nt s
Th et e mp er a t u r ean dp r e s su r ei n s t r u me ntc on ne c t i o nsar el o c at e dt h r o ug ho utt h et o we r .Th et e mp er a t u r epr o bemu s tb e l o c at e di nal i q ui ds p ac ea ndt h ep r e s su r ec o nn ec t i o ni nav a po urs p ac ea ss h owni nFi g. 10.
Fi g1 0-T y pi c al T emp er a t u r ea ndPr e s su r eI n s t r u me ntNo z z l eL oc a t i o n Thel e vel i ns t r ument sar el oc at edi nt hel i qui ds ec t i onoft het owerus ual l yatt hebo t t om.Theel e vat i onoft henoz zl esi sdec i ded b yt heamou nto fl i q ui dbe i n gc on t r ol l e do rme as ur eda ndb ys t a nd ar dc on t r o l l era ndg aug eg l as sl e ng t h s.Le v el c ont r o l l e r s mu stb eo pe r a bl ef r o mg r a deorp l at f or m an dl e v el g aug es/s wi t c he sma ybef r om al ad de ri fn op l a t f or mi sa v ai l a bl e . Fi g. 1 1,1 2,1 0,1 3&1 4i l l us t r at esaf e wi ns t r umentc onnec t i onsont o wer .
Fi g11-T y pi c al I ns t r ume ntVe ss el
Fi g12 -T y p i c al Ar r a nge me ntf o rL ev e lI n st r umen t
Fi g13 -T y pi c a lT emp er a t u r ean dPr e s s ur eI n s t r u me ntAr r a ng eme nt s
Fi g1 4-T y p i c a lCo mmo nBr i d l e L ev e lI n s t r u me ntAr r a ng eme nt
3 . 0Ac ce ssa ndMa i nt e na nc eFa ci l i t y 3. 1 Ac ces swhe t heri nt er nal ore xt er nal i sv er yi mpor t ant .Thi si nc l udesac c es si b i l i t yofc onnec t i onsf r om l adder sandpl at f or ms andi nt er nal ac ces si bi l i t yt hr oughshel l manhol es ,handhol esorr emo vabl esec t i onsoft r a ys . 3. 2T owermai nt enanc ei sus ual l yl i mi t edt or emo val ofe xt er i ori t ems( e . g.r el i eforc ont r ol v al v es )a ndi nt er i orc omponent s( e . g. t r a ysorpac k i ngr i ngs )Handl i ngoft hes ei t emsi sac hi e vedbyfi x edde vi c es( e. g.da vi t sort r ol l e ybeams )orb ymobi l e e qu i p me nt( e . g .c r an es ) .Wh enda v i t sorbe amsar eu sed ,t he yar el o ca t e da tt h et opo ft het o we r ,a cc es s i b l ef r o m apl a t f or m a ndde si gn edt ol o we rt hehe av i e str emo v ab l ei t em t oas pe ci fi cdr o po utar e aa tgr a del e v el . Wh enmo bi l eeq ui p me nti su s ed ,ac l e ars p ac emu s tb ep r o v i d edatt h eb ac k( s i d eo pp os i t et o pi per ac k)oft het owert hati sac ces si bl ef r om pl antaux i l i ar yr oad.
Fi g.1 5,1 6,1 7&1 8i l l u st r a t est heac c es san dma i n t e nan cef a ci l i t i e st ob ec on si de r edi nt hep i p i ngar r a ng eme ntar o un da t o wer .
Fi g15 -Pl a t f o r m Wi d t hRe qu i r e me nt s
Fi g16 -T y p i c a lAr r a ng eme nto fEx t e r n al Pi p i n ga r o un dCo l u mn
Fi g1 7-T y pi c a lOp er a t o rAc c es s
Fi g1 8-T y p i c a lPl a na ndEl e v at i o nVi e wo fT owe rAr e a Onf r ees t andi ngcol umns ,ac c es sf ormaj ormai nt enanc et oi ns ul at i onorp ai nt i ngwi l l us ual l yr equi r et heer ec t i onoft empor ar y s c aff ol di ng.Spac ef ors caff ol di ngatgr adel e vel andpr o vi s i onofc l eat sont hes hel l t of ac i l i t at es c aff ol der ec t i ons houl dbe c o ns i d er e d. 3. 3 Ut i l i t ys t at i onsoft woser v i c esv i z .s t eam andai rar eus ual l ypr o vi dedonmai nt enanc epl at f or ms . St ea ma nda i rr i s er ss ho ul dbel o ca t edd ur i ngpi p i n gs t u dyt ok ee pa de qu at ecl ea t sf o rs u pp or t . ( s eeFi g. 1 9)
Fi g1 9-T y pi c a lPl a t f o r m Ar r a ng eme nt
4. 0Pl at f or msandLadder s 4 . 1 Pl a t f o r msont o wer sar er e q ui r e df orac c es st ov a l v e s,i n st r ume nt s ,b l i nd sa ndma i nt e na nc ea cc es s es .Pl a t f o r msar e nor mal l yci r c ul arands uppor t edb ybr ac k et sat t ac hedt ot hes i deoft het ower .Gener al l y ,ac ces st opl at f or msi sbyl adder . Fi g. 20i l l us t r at est hepl at f or mr equi r ement s .
Fi g2 0–T o we rP l a t f o r ma ndLa dd erEl e v a t i o nRe qu i r e me nt s 4 . 2 Pl a t f o r me l e v at i on sf ort o we r sa r es etb yt h ei t e mst ha tr equ i r eop er a t i o na ndma i n t en an ce. Themaxi mum l adderr unshoul dnotexc eed7m. 4 . 3 Pl a t f o r m wi d t h sa r ed i c t a t e db yo pe r a t o ra c c e ss .Th ec l e ars p ac eo np l a t f o r m wi d t hsh al l b emi n . 9 00 mm. Forpl at f or mswi t hc ont r ol s t at i ons ,t hewi dt hofpl at f or ms hal l be900mm pl ust hewi dt hofc ont r ol s t at i on. Th ep l a t f o r mf o rma nh ol e san dma i n t e na nc eac c e s s ,a de qu at es pa c ef o rs wi n gt h ec o v e rfl a ng efl a ng emu s tb ep r o v i d ed . 4 . 4T ophe adpl a t f o r msf o ra c c es st ov en t s ,i n st r u me nt san dr e l i efv al v esar esu pp or t e do nh ea db yt r u ni o ns . 4 . 5 Ac c e s sb e t we e nt o we r sma yb ec o n ne c t e db yc o mmo np l a t f o r mi n g . 4. 6I ti spr ef er abl et os pac epl at f or m br ac k et sont o werequal l yandt oal i gnbr ac k et sov ereac ho t hero vert heent i r el engt hof s hel l .Thi smi ni mi z est hes t r uc t ur al des i gnandi nt er f er enc esf r om pi pi ng. 4. 7 Onver ywi depl at f or msort hos et hats uppor thea vypi pi ngl oads ,k neebr ac i ngi sr equi r edi naddi t i ont ot heus ual pl at f or m s t e el .Thep ot en t i a lo bs t r u ct i o ni mmed i a t el yun de rt h ek neebr a cemus tb ek ep ti nmi nddu r i ngpl a t f or m de si gn . 4 . 8Fi g.3 ,15 ,2 1,22 ,2 0&1 9 i l l us t r at esaf ewpl at f or mc ons i der at i ons .
Fi g21-T ypi c al Pl at f or m Or i ent at i on
Fi g22-Det ai l sofCi r c ul arPl at f or m Br ac k etSpac i ngs
I nt r oduct i on Towers also referred to, as columns are one of the principal pieces of equipment of any processing facility. Towers are cylindrical steel vessels that are used for distilling raw materials in the production of such products as gaso line, diesel, and heating oil. The plant layout designer must understand the internal structure of a tower and how it operates to produce a satisfactory design. This chapter highlights the general requirements for the tower plant layout design. It describes the internal workings of towers and provides the information required to orient nozzles; locate instruments, piping, and controls and provide platforms and ladders for the operator and maintenance access.
TheDi st i l l at i onPr ogr ess Crude oil is of little commercial use; when separated, or broken down, however, oil becomes one of the mos t valuable commodities in the world. Crude oil is a miture of hydrocarbon compounds with a wide range of boiling points from !"" "# $%& "C' to !("" "# $)*"" C'. +eparation or distillation is a process by which a liquid miture is partially vaporized. The vapours are then condensed, separating the individual components of the miture. s the temperature of crude oil is raised, the initial boiling point $I-' is reached. s boiling continues, the temperature rises. The lightest material, butane, is produced first, at I-, /ust below !"" "# $%& "C'; the heavier materials are produced below &" "# $(0) "C' The residue includes everything above &" "# $(0) "C' . The evolution of distillation towers is best eplained in three basic steps.
1 The batch shell still process 1 The continuous shell still process. 1 The fractional distillation process.
Bat chShel l In the batch shell still process, the still is partially filled with a set feed called a batch. The feed is then heated to the temperature required to produce a specific product from the overhead vapours. This process is repeated each time for each product until the batch reaches the maimum temperature for the range of products specified. The feed remaining in the still is then pumped out, and the still is allowed to cool. It is then refilled, and the whole process is repeated 2ot only is this process time consuming but also the product is not always of high quality. The batch sheet still process was one of the earliest used for liquid miture separation.
Cont i nuousShel l In the continuous shell still process, several sh ell stills are linked in series to form a battery. #resh feed continuously enters the first still, which is kept at the lowest temperature for the lightest overhead product. The bottoms from the first still are fed to the second still, which is kept at the temperature for the net highest boiling overhead product and so on for the number of products needed. If the feed and the temperature of each s till remain constant, the finished product is of satisfactory quality. The continuous shell still process, which is an improvement over the batch shell still operation.
Fr a ct i onalDi st i l l at i on +imilar to the continuous shell still the fractional distillation process is made up of several stills linked together in series. The main difference is that all the liquid condensate is returned to the upstream still s the feed is partially vaporized in the first still the vapours rise, travel through the overhead line, and come into contact with the liquid in the second still. -ecause the temperature of the liquid in the second s till. -ecause the temperature of the liquid in the second still. -ecause the temperature of the liquid in the second still is lower than the incoming vapours from the first still, the vapours partially condense. t the same time, liquid from the second still enters near the top of the first still. s vapours rise in the first still, they meet the incoming liquid from the second still.
Dr awi ng This causes vaporisation of the incoming liquid from the second still and condensation of the rising vapours in the first still The same reaction takes place in all the downstream stills. This process improves on the previous operations in terms of quantity, quality and a reduction in the energy needed to heat the raw materials. ll three3process arrangements are satisfactor y operations and play an important part in the development of the modern distillation tower. The final step in combining these operations into one single component is achieved by stacking the stills one on top of each other and installing an internal device between each still to allow the liquid to flow down and the vapors to rise. This means that the single unit can function in a way similar to the multi shell unit for less capital and operational cost. The reflu return line controls the temperature of the fluids in the upper portion of the tower.
VapourandLi qui dFl ow 4ne of the most common internal devices that allows the single tower to function similarly to the multi still unit is the tray. +lots and holes in the trays allow the vapour to rise and the liquid to flow down. 5ising vapours in the tower pass through slotted bubble caps and come i nto contact with liquid flowing around the caps. 6iquid flowing down from trays above falls through the down comers and over and around the bubble caps round to the net drwncomer. In this manner, the lighting boiling fractions in the down flowing liquid are vaporised by the heat from the rising vapour and heavier boiling fractions in the vapour are condensed and flow down the tower. This process of vaporising and condensing throughout the tower allows the feed to be separated into the required boiling3range fraction, which are drawn off from the side of the tower at the appropriate location.
TypesofTower s
Towers are named for the service or type of unit they are associated with for eample a stripper is used to strip lighter material from the bottoms of a main tower or a vacuum tower. It is generally used in a vacuum crude unit for distilling crude bottoms reside under vacuum pressure. #rom the outside, tower configuration are similar in appearance, varying only in dimension. +ome towers have swaged top and bottom section. The principal difference among towers is the type and layout of the internal components that controls the vapor liquid contact. This chapter describes the internal and eternal plant layout requirements for the two most common types of tower7 the tray and packed arrangements and a typical tray tower with some of its associated components. In a packed tower, instead of having trays, the units are packed with beds of metal rings. 4n entering the tower the liquid passes through a distributor that route the liquid evenly down through the packed beds of metal rings. 5ising vapours passing through the beds come into contact with the descending liquid a manner similar to the tray tower operation, the liquid is partially vaporise by the heat and the vapours are condensed by the cooler liquid.
Desi gnConsi der at i onf orTower s Towers are not a standard operation they are usually located within a process unit ad/acent to related equipment and in a suitable position for operator close to such related items as pumps re boilers drums and condensers and should be in position to facilitate an orderly and economic interconnection between itself and that equipment. 8ithin the conventional inline process unit, towers and their related items are located on either side of a central pipe rack serviced by auiliary roads for maintenance access in plants in which the related equipment is housed, the towers is of ten located ad/acent to the building or s tructure containing the equipment.
TowerEl evat i onandSuppor t Tower elevation is the distance from the grade to the bottom tangent line of the vessel. +upport is the means by which the vessel is retained at the required elevation.
lthough the tower elevation must satisfy minimum 2+9 requirements, it can be set by a combination of the following constraints : whichever produces the minimum tangent line elevation. •
2+9
•
4perator access
•
aintenance access
•
inimum clearance
•
•
Common access
skirt is the most frequently used and most satisfactory means of support for vertical vessels, It is attached by continuous welding to the bottom head of the vessel and is furnished with a base ring, which is secured to a concrete foundation or structural frame by means of anchor bolts In most cases, the skirt is straight but on tall, small3 diameter towers, the skirt could be flared ccess openings are required in vessel skirts for inspection and when possible should be oriented toward the main access way a typical s kirt arrangement. The first step in tower layout is setting the bottom tangent line elevation. This step assists civil engineering i n foundation design, vessel engineering in support design, systems engineering in line sizing and rotating equipment engineering in pump selection to set the elevation of a tower, the plant layout designer requires the following information. 1 Tower dimensions 1 Type of heads 1 +upport details
1 2+9 requirements 1 -ottom outlet size 1 5eboiler details 1 #oundation details 1 inimum clearances #or eample, the tangent line elevation of the tower has been set using the following information and the guidelines in this chapter. Configuration 3=hibit !"3 !% $operator access' Tower dimensions (ft $!,0""mm' in diameter by *" #t $!&,%""mm' in length Type of heads3 07! elliptical +upport : +traight skirt with base ring 2+93 * #t $!&"" mm' minimum. -ottom outlet size : * in diameter #oundation : Concrete point of s upport elevation of !"! ft $!"",%""mm' 4perator clearance : ) ft $0,!""mm' freehand sketch should be used for this eercise. lthough the minimum 2+9 requirement was a key factor in elevating the tower in this eample, the height was finally dictated by operator access clearance , which was the greater of the two dimensions. If the configuration had been used the tangent line elevation would be !"&.> ft !" 0,*""mm'.
T owerI nt er na l s
Towers have a variety of internal devices for vapour liquid contact and feed distribution that affect the eterior layout of the vessel. There is a wide range of designs for trays, which are the principal internal component of the tray tower. The two most frequently used are the single pass bubble cap trays $e.g sieve or perforated trays' are similar in design to the bubble cap tray and do not affect the layout of the tower, Tray configuration and dimensions are furnished by process engineering and are included in the process release package. Towers have the same tray configuration for the whole length of the tower. +ome towers, however, especially those with enlarged sections could change from single : pass to double pass tray configurations. The chimney tray, if specified is another device that could change the tray configuration. The chimney tray is a solid plate with a central chimney section and is usually used at draw off sections of the tower. The plant layout designer must orient the trays along with the tower nozzles to suit the best eterior arrangement. The tray can be at any angle as long as the downcomers directly oppose each other. Two main items that influence tray orientation are maintenance access ways and reboilers. The process vessel sketch that the reboiler draw off nozzle is located directly below the downcomer of tray 0 and the plan arrangement indicates that the reboiler is located on the west side of the tower and that the maintenance road is south of the tower. Therefore, because the tower reboiler nozzle is generally on the same side as the reboiler and the maintenance access way is best located on the maintenance side, the trays are automatically positioned about a north south centreline. The principal difference between the travel and the packed tower is that the packed tower uses metal rings instead of trays for vapour liquid contact The metal rings are dunped or pac/ed into specific sections of the tower, called beds and supported by cross grid bars spaced to prevent the rings from falling through. The supports are designed to allow vapour to rise and liquid to flow down. 6iquid is fed into the vessel at the top of each bed through a liquid distributor. ?nlike the tray tower, there are no special considerations for orientation of the beds, the distributor, or the packing supports.
Noz z l eEl e va t i ona ndOr i e nt a t i on
2ozzles must be elevated to meet the i nternal requirements of the tower and oriented for maintenance and operational needs. Their position must also facilitate economic and orderly interconnection of piping between the tower and related equipment. maintenance access is usually located at the bottom; top and intermediate sections of the tower and is used to gain entry to the tower during shutdowns for internal inspection and component removal. aintenance accesses must not be located at the down comer sections of the tower. Care must be taken at the sections of the tower that contain internal piping to avoid blocking the maintenance access entrance. #eed connections to trayed towers usually must be located in a specific area on the tray by internal piping. 8hich can restrict nozzle orientation options. The restrictions are minimized by optional routing of the i nternal piping to facilitate the most economic eterior arrangement Internal feed piping to packed towers is piped directly to the distribution and can be o riented at any angle. If specified, reboiler connections are usually located at the bottom section of the tower. #or the horizontally mounted there mosiphon reboiler the off nozzle is located /ust below the bottom tray to the vertically mounted recirculating the boiler. The draw off nozzle is located at the -ottom head for both systems, the return nozzles are located /ust above the liquid level . The vapour outlet is usually a vertical nozzle located on the top head of the tower. It is usually a single nozzle but in certain cases $e.g. towers with very large diameters' more than one nozzle is specified on large : diameter vapour lines, the vessel connection could be welded instead of flanged. In addition the vent and relief valve could be located on the top head instead of attached to the overhead piping. The liquid outlet is located on the bottom head of the tower. If a skirt supports the tower the nozzle is routed outside the skirt. s with the vapour outlet, when more than one nozzle may be specified the elevation of the nozzle is dictated by the constraints discussed previously in this chapter. The orientation can be at any angle but generally it is dictated by pump suction piping fleibility.
Temperature and pressure instrument connections are located throughout the tower. The temperature probe must be located in a liquid space and the pressure connection in a vapour space. The preferred location for both connection level instruments are located in the liquid section of the tower, usually at the bottom. The elevation of the nozzles is dictated by the amount of liquid being controlled or measured and by standard controller and huge glass lengths. This information is furnished on the instrument vessel. 8hen nozzles especially those with internal piping are positioned the plant layout designer must show adequate clearance at tray support steel illustrates approimate tray support beam sizes indouts are measured from internal diameter of the vessel to the face of the flange. To set top and bottom head nozzle elevations. The type of head must be specified. The information is highlighted in the process vessel data. The two most commonly used are flanged and dished and 07! elliptical heads. s an eample, the nozzle elevations have been set using the following guidelines. 1 rocess vessel sketch 1 Tray details 1 Type of heads : 07! elliptical 1 -ottom tangent line elevation 1 2ozzle summary 1 Instrument vessel sketch 1 iping and instrumentation diagram 1 lant layout specification 1 Insulation : 2one required
Pl at f or m Ar r angement s latforms are required on towers fo r access to valves instruments, blinds, and maintenance accesses platforms are usually circular and supported by brackets attached to the side of the tower. @enerally access to platforms is by ladder.
latform elevations for towers are set by the items that require operation and maintenance and by a maimum ladder run of %" ft $A!>"mm'. latform widths are dictated by operator access for intermediate platforms with no controls are required and platforms with controls located to the side or the edge of the platforms. The width must be a minimum of % ft $A!>mm' plus the width of the controls or sections for maintenance access platforms, adequate space must be provided to swing the maintenance access flange open for storage against the face of the Top head3 mounted maintenance access must be from three sides for typical maintenance access arrangements. Top head platforms are required for access to vents, instruments, and relief valves and are supported from the head by trunnions. Typical top head platform arrangements. ccess between towers, if layout permits. Is provided by common plat forming. The platform elevations can be within a maimum difference of A in $0%" mm' but must be connected by mechanical /oint. -rackets for side3mounted platforms are evenly spaced around the tower and when possible, straddle both the main aes. 4ddly angled brackets can be used for small platform etensions as long as the bracket clip does not interfere with the ad/acent support. =hibit !"3 (* is an approimate guide to bracket spacing.8hen a common ladder serves two or more platforms, the ladder rungs must be level with the platforms they serve. The platform elevations must be in even increments to suit the standard !03in $%""mm' ladder rung spacing. 6adders at tower transition sections and at flared skirts may be sloped, if required, to a maimum angle of !> from the vertical. 4ffsets in ladders should be avoided 4n very wide platforms or those that support heavy piping loads, knee bracing is required in addition to the usual platform steel. The potential obstruction immediately under the brace must be kept in mind during platform design #or eample, the platform elevations show n on the process vessel. These are minimum requirements for instrument, valve and maintenance access.
TowerPi pi ng Tower piping is located in con/unction with tray nozzle and platform orientation. 8hen possible the piping is grouped for case of support and positioned to accommodate interconnection with related equipment and the pipe rack ,The preferred areas of division for piping platforms and ladders. dequate space must be provided between piping and between the back of the piping and the tower shell to facilitate the installation of pipe support which are attached to the tower.
Tower piping should be arranged with sufficient fleibility to accommodate tower growth and to allow interconnection to equipment during regular operating conditions. 5elief valve systems that are open to the atmosphere are located at the top of the tower closed systems are located a minimum distance above the relief ledder. s an eample the piping arrangement has been designed using the following information and the guidelines in this chapter •
rocess vessel sketch
•
Tray details
•
2ozzle elevations
•
Instrument vessel sketch
•
iping and instrumentation diagram
•
=quipment arrangement
•
latform arrangement
•
2ozzle summary
•
lant layout specification
TowerI nst r ument s
6evel, pressure and temperature instruments control the operation of the tower and must be placed in a position that enhances operation and maintenance without obstructing operator access. Instrument requirements for towers are usually h ighlighted on an instrument vessel sketch furnished by the instrument engineer. 6evel controllers, switches and gauges are either lo cated individually or grouped on a common bridle or standpipe. The controller must be operable from grade or a platform; gauges and switches may be operable from a ladder if no platform is available. 6ike level gauges temperature and pressure instruments can be operable from a ladder if a platform is not available at the required elevation. They can be read locally or in the main control room. ounted indicators are available in a variety of styles with straight or swivel heads that can be positioned for clear dial visibility. The instrument arrangement has been designed using the following information and the guidelines in this chapter. •
2ozzle elevations
•
Instrument vessel sketch
•
latform arrangement
•
iping arrangement
•
6evel instrument locations
