-AND---- .. ..II'1IIl1Ed Bausbacher III Roger HuntI / I"PROCESS PLANTLAYOUT ANDPIPING DESIGN"PROCESS PLANTLAYOUT ANDPIPING DESIGNDEdBausbacherRogerHuntPT R Prentice Hall, Englewood Cliffs, NewJersey 07632Library of Congress Catalogingin-Publication DataBausbacher, Ed..Process plant layout and piping design I Ed Bausbacher, RogerHunt.p. em..Includes index.ISBN 0-13-13862981. Chemical plants-Design andconstruction. 2. Plant layout.3. Chemical plants-Piping. I. Hunt, Roger (Roger W.) II. Title.TP155.5.B38 1993660- M tl} M Minimum to suit operator or

'z:1:-k1lImaintenance access''''74>'''''''jh1;1! NA Nor applicable.,f!,?lSo Z"" Z'!C 1:0:;.:g '}!703;a ;11 G! :1"l\r:tt10

II, M""." ... ., "" ''''' ''''' '''' N' I. il.s t" ,,)I11_M,"" "" ''''' I"" "'" Ivl ..... 4.C1J f j 1'2::> 'Z>Ic:oIIJb Ic:c H H H ? S Mi2tl.. :a p:v-. Dl.::i-J W''''' I... ,"",.".,,., "" ,.< "'" ,,, "" ...NAII Ii t I;"M......, 1M l.x> 3;:: IV! leo 30INA; ':l!'; J 4::to170It;ro100 100 ",0M ?o ':l..;:>c 10'1 i'Z. I, ";l M M'?oIll%:' 1170 ICO 2a:>1Do!'7a:;> M1&r:' r;c!v NANANAr. If: '1 ()O 1% !PoIC'\::>10010 NA t-J A\ 7'" "-'1 g>,e 'l"o 11;01.".., 100 '';0'" ..NAtlo. ;.:. 1M1M !;rK'''lc:: 'lco 1co lco'ta;> em!zoo ex. 1"7a 1\1.... i'Jl\ Ic", '.>0 tv! .!A\ ",'tl ( ta:;l It;Q1J>()100 lao 12mI1.Do70 bZJ7 NA1\J.6.Mlv1 WI M :t'.) i'l1:2-,.,., "'.11="'" ... ..." '"b ,., ." NA>JA "" "'" "" 1 14>'7q, 10taoII;c>1M NAt-lA I, Il;. Ie;. If? tv! MIIe' M NA1),( i: ?t:o ltVex> 'SoSt;>'70 1M!"lc;. ?o tv! 1'5>l? M M ?l::'> t..A tv!10 Iv1 NA t-JA MM IV! M M1M M t--tl I-J1 N1 t.I1 MI..."Notes:Exhibit21highlight!> the recommended safety distancesbetween eqUipmentassociated with refinery, chemical, andpeuocllemical plants.1bis exhibit should be read in conjunction with national andlocal codes andregulations. Exceptions to this exhibit should beby client specification only.Dimensions shown are to the face of eqUipment and areminimum.Fixed fire water sprays should be provided over equipment thathandles flammable materials and operates at temperaturesgreater than 500 F (2600C) and over equipment that handleslight hydrocarbons with a vapor pressure greater than 65 pst kg/em) at100 F (:S8 C) Or a dischargegreaterthan 500 psi (35 kg/em) that is located directly beneathaircooled exchangers.a. English Measurement .'Large vacuum or crudetowerswithswaggedbot-tom sections and compressors that are to be elevatedfor operationalneedsmust besupportedfromcon:"crete structures. Equipment that must be elevatedforprocessrequiremenr.s (e.g., shelland tubeoverheadcondensers)mustbe supportedinstructures. Whenpractical, aircoolers shouldalsobesupportedfromProcess Plant lAyout and Piping Designoverhead pipe racks. Equipment elevations must be inaccordance with Exhibit 2-2.Roads, Paving, and RailroadsProcess plants are to be serviced by roads adjacent toprocess units, utility planr.s, materials-handling and21$&EXHIBIT 2-1 Equipment Spacing (Cont)fIV[A)Key:

A Can bereducedto a minimum of61m by increasing heighr of flare

B Boilers, power generators, air compressorsC Monitor iocations shouldbe

selected to protect specific items0jtequipmentID Greater chan2600C ..!>I:"r?I7.... E Less than2600CtJN'TF The diameter of thelargesttankI kWf' I"(t;X G Double rhe diameter of the largestt _ lY J \V \})J tank tv1 NA&1H Maximum 75m; minimum will va-lUlU Ib" ,,7.A:.:. 1';;'; 'M MIl' f j::> ?> iho !do !>o r;o ("c I!? w I'"1A.'? NA t-lA1'7 MM1 '"

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'STA.(:.I'&t:;.> E.l;? '",.;"".". ~ ., . .,..Process Plant Layout and Piping DestgnIIE X H I B I T ~ ~ 9Setting Elevations ofSteam Turbines8182tu t!COmpressor Drive ElevationArrangement Arrangement GovemedByA C CA D AA Electric motOr AB C CB D NAB Electric motor NA$RemarksMotornotshownUsually grade-mounted arrangementUsually grade-mounted arrangement, mOlornot shownEXHIBIT 4-40Criteria for SettingMachineElevations IooJ Oet?J'Ul?AMPE-t-JS'1ZmrnIBIT4-41Setting Elevations ofReciprocatingCompressors7. Dimension from the centerline of the dampener tothe faceof the nozzle-Setby vendor.8. Bottomofthecompressor baseplate tothecen-terline of the compressor shaft-Set by the vendor.INTER- AND AFfER..COOLERSInter-coolers Coolersareprimarily usedtoreducetheoperatingtemperaturewithina compressorcir-cuit, which allowsthe use of a smaller machine withfewercylinders. These coolersmay varyinsizeandtype (e.g., shell and tube, air coolers, and U-tube) andshould be located as dose to the compressor as prac-tical. In some reciprocating compressor arrangements,the coolers may be mounted on and directly over thecompressorbythevendor, but theyare lo-catedby the engineering contractor doseto the rnachineor stagesuctiondrum. Exhibit 4-42showsacentrifugal compressor with its inter-cooler and inter-connectingpiping between stagesas supplied by thevendor. Exhibit 4-43 shows areciprocation compresSOl' withall components, includingtheinter-cooler.suppliedseparatelybythecontractor. Furtherrefer-ence[0thiscanbeseeninExhibit 436, wheretheintercooler to compressor1 is mounted separately at(110"'-- grade, parallel to the compressor shaft. The inter-:ooler (0 compressor 3 is mounted at grade, perpeniicularto thecenterline of the shaft, andissupplied)y the vendor.U'ter-coolers After-coolers are usedto reducethe>peratingtemperatureof thegaswhenit leavesthe:ompressor, whetheritcontinuesthrough additional)rocessequipmenr oreorersapipeline inwhich itnust have a specific temperature. After-coolers may beDcated farther away from the compressor than shownfl Exhibit4-37becausetheprimary pipingdoes 001eturn to the cooler. Exhibit 4-44 shows a typical after-ooler piping andinstrumentation diagram.lOUSING AND PLATFORMtEQUIREMENTSlhena compressor iscovered-partially ortotallyflclosedbyashelterorstructure-manyelementseterminehowthelayout must beapproached. Thectorsto consider are:Operation-Theplant operationspersonnel needroom to walk safely around the machine, They musthave access to valves, switches, and gauges and mustbeabletoseeall gauges, lights, anddialsonthecontrol panels.Maintenance-All principal components tobe reomovedduringmajor maintenancemust beabletobeliftedbythetravelingcrane, swunglaterallytothe de-ar area(designatedinExhibit 4-33),andre-moved fromthebuilding.::Jimateconditions-Installationin temperate c1inates may require only a roof that provides limited)rotection from the elements. In warmer climates, a:urtain wall structure may be the right application. A:urtain wall has a complete roof and four sides thatIre open fromthe operating level to a height of 8 ft2,400 mm). The roof bLocks the sun for most of the83EXHIBIT 4-42 CentrifugalCompressor withInter-Cooler and Piping Between Stagesday while allowing coolerbreezestopassthroughthe structure. Thisinstallationmayalsobe usedinareas with significant rainfall. Totally enclosed struc-tures are usually proVided in severely cold climates, Safery-The housing must have easy access through.out, ample ventilation as prOtection from potentiallydangerous gas leaks, anda sufficient number ofdoors and stailways in the event of an emergency... Economics-The area inside the building should belarge enough to satisfyall other factors and nolarger, unlessspecificallyrequestedbyaclient toaccommodate future equipment within thestruc-ture.Exhibit 445 shows how to size a building, regard-less ofwhat type of machine isu s e d ~ the example is formrnmlT 4-43 AReciprocating Compressor with AllComponentsEXHIBIT 444 AfterCooler Piping and InsrrumentationDiagrampressorend, there must besufficient roomfor theoperators and any routinemaintenance, as showninblock B. Although the operator must have access to thefront of the control panel, it may also be necessary toallow access to the rear of the panel for maintenance,shown as clearance D.-... -a centrifugal gas compressor. The elements to be sizedare discussed in the following sections.Floor elevation TIle operating floorelevationis es-tablishedbymakingall standardallowancesaroundand above equipment andprovidingtheusualhead-roombelow all horizontal piping runs andconduits,as shown by blocks E and F and Exhibit 4-45.Building elevation Theelevationof thebuildingisfurther established by determining the size of the dearmaintenance area (shown as Xby Y). This area mustaccommodate the largest single piece to be maintainedat a minimum elevation above all operating floor re-quirements, shownas clearance AThe alternativemaintenanceareamaybeusedif thisarea. is dearthroughout the lengthof the building.Building width The width of thebuildingis estab-lished by first allowing space for the largest compres-sor train. There must be adequate room between thesteam turbine, lube oil drain piping, and any miscella-neous piping that may be arranged along the adjacentwall, as shown by block C in Exhibit 4-45. At the com-Hook centerline elevation Thelayout designer de-termines the centerline elevationof thehook. Themaximumliftedloadmust be supplied tothestruc-tural engineer orbuildingcontractortofurnishthecorrect traveling crane. The eave elevationis then seton the basis of the clearance of the crane selected.Process Plant lAyout andPiPing Design.'85EXHIBIT 445Compressor Shelter:Sizing CriteriaGENERAl COMPRESSOR lAYOUTfhis section highlightS additional features to considerinthedesignof a centrifugal orreciprocatingcom-~ r e s s o r layout. Thereare manyways todevelopa:ompressor layout, but certainaspectsof thesema-:hines dictate how best to approach a design that opti-nizes operation, maintenance. and safety while adher-ngto economic requirements.:entrifugal Compressors:' InJet PipingX/ith higher compressor velocities and rotatingpeeds, theplant layout designer must givegreater:onsideration to the compressor inlet line. The ASMElower test code requires a minimum of three diame-ers of straight run piping between the elbow and thenlet nozzle. Often, however, such factors as gas veloc-ties, molecular weight, and temperature must be con-idered forthe optimumlayout. An equipment engioleer should be consultedat the outset to develop alasecase layout requirement. The preferred design is,ne in which the horizontal run is parallel to the com-,ressor shaft, assho'WIl inarrangementAof Exhibit-46. (In these examples. it isassumed that the com-ressor inlet sizeis 12inandthat therequiredLimensionforthisparticular gas compressorisfouriameters.) The compressor elevation can be affectedby the various layouts. Another factor that could influ-encestraight runrequirements is theneedtoinjectwashwaterinto the gasstreamto dean compressorblades,as shown in Exhibi[ 4-47.Suction Line StrainersCompressor suction Jines must be free of any foreigl1panicles [hat coulddamagetheinternalsof the m a ~chine. Strainers are installed in the inlet line betweenthe block valve and the compressor inlet nozzle. Afterthe unit has been on stream for some time. the strain-ers:ire normally removed. Should the strainer be thepermanent type, aclean-out connection must beadded to remove any trapped foreign matter during ashutdownof the compressor. Exhibit4-48 illustratestwo such applications.Break-Out FlangesAll linesto a compressor that mustberemovedformaintenance of thecompressororstrainerremovalmust have a set of flanges in the line in addition to theset at the compressor nozzle. Exhibit 449 shows oneline with a built-in extra set of flangesat the shut-offvalve andanother linefor which flanges must bea d d ~ d becausetherearenootherflangesnearthecompressor case.ComjJreS$on86I ~lot~ ~ ~ A ~ M F f ~ ~ ~EXllmIT 4-46Compressor SuctionConfigurations87&';$j?t?A,( tJ (;) ZZU;;J"z,1I L! t-JE;-EXH1B114-47WashWater Injection,: :iscellaneous Piping ConnectionsIe plantlayout designer must review both the engi-~ e r i n g contractor and the vendor piping and instru-entation diagrams to ensure that all connectionsve been piped up by one or the other.imary operating valve accessibility AU operat-~ valves must beaccessibletotheoperatorfromade or the operating platform around the machine.Ivesthat arephysically outof reachmay be madeaccessiblethroughextensionstemsorchainopera-tors, Exhibit 4-50 shows some of these variations.High-Pressure Steam Inlet PipingTo streamline the high-pressure. hightemperaturesteam inlet piping to the turbine, the plant layout de-signer should review the compressor outline drawingto locate the neutral axis. At this point, the turbineisanchoredtothesteel frame. AsdepictedinExhibitCompressors..,88EXHIBIT 4-48Inlet Line StrainersItItLEXHWIT 4-49 Maintenance BreakOut Flanges EXHIBIT 451 High-Pressure Steam Inlet PipingEXHWIT 4-50 Operating Valve Accessibility451,locatingthe line anchorclosetothispoint en-ablesthe designertogenerate alayout with a mini-mum amount of leg, thereby satisfying the stress andflexibility requirements in this particular system., IG,!lpll'" I'Q W O ~ dStraightening VanesWhen the straight run on the inlet piping is less thandesired, a straightening vane may be installed to.smooth the flows and improve the compressor perfor-mance. These vanes must be in accordance with ASMEor American Gas Association standards. If use of vanescanbetolerated, the lengthforany arrangement (a.c;illustratedin Exhibit 4-46) can be dividedby four,Reciptocating Compressor Piping ,Poorly designed reciprocating compressor pipingcauses pulsation that can reduce machine capacity andincrease horsepower requirements. Line design. should be simple and run as low to grade as possibleto facilitate support Once the compressor piping hasbeendesigned, theproposedconfigurationis subjectedtoananalogstudythat maybedonebytheProcess Plant Layout and Piping DesignEXHIBIT 4-52Compressor UneBranchesEXHWIT453Compressor Supportslendororanindependent testinglaboratory. Simu-,ated by electrical circuits, this analog study identifies)otentially damaging accoustic or pulsation problemsjuringthedesignphaseof theproject, eliminating1igher repair and redesign costs at a later date.Line Branches\11 branches should be located close to a line supportN'heneverpossible. Any suchconnectionsshouldbelocated on the top of the piping tominimize any potential liquidcarryover. Exhibit 4-52shows typicalbranch connections.Compressor Pipe SupportsExhibit 453 illustrates how to minimize the transmis-sion of damaging vibrations by isolating theline sup-portS fromadjacentcompressor or building founda-tions, operating floorsteel, or building framing.Compt-essors90Drain PipingAmple drain piping must be provided on suction anddischarge pipingtoavoidliquid intothecylinders. On multistage machines, care must be takenwith the drain header system to avoid piping up a pressure drain into ahigh-pressureheader. Doing soforces the liquids into the lower-pres-surecylinders. Compressorshavesmall amountsofga...., leakage at the stuffing box. which is usually pickedup in the distance piece bet\Veen the cylinder and thecrankcase.Ga.. e:.IZ..n N ~Pl..ATFt:::JIZ.MI-f:,VI'!:.L.EXHmlT S-18 Plarfonn Arrangement at a VerticalDrumPLATFORM ARRANGEMENTSPlatforms are requiredat drums for access to valves,instruments. blinds, andmaintenance accesses. Exhibit 5-17 illustrates a platform arrangement at a hori-zontal drum, andExhibit 518displaysthearrange-ment for a vertical drum.EXHIBIT 5-17Platfonn Arrangement ata Horizontal DrumFor tall vertical drums, platforms are usually circu-lar and supported by brackets attached to the shell ofthedrum. Platformsat horizontal drumsareusuallyrectangular and are supported by brackets attached tothe concrete piers supporting the drum or trunnionsattached to the shell of the drum, or bystructural steelsupported from grade. Drums located in structures, ifsize permits, use the structure floor for access to controIs. Topheadplatforms onhorizontalandverticalinstallationsaresupportedbytrunnionsattachedtothe vessel head. Generally, access to freestandingdrumplatformsisbyladder. Typical drumplatformarrangements are shownin Exhibit 519.Platform elevations fordrums are set by.theitemsthat require operation and maintenance. On tall vertical and high elevated horizontal drums, the platformelevations are determined by a maximum ladder runof 30 ft (9.150 mm). Exhibit 520 illustrates horizontaldrumplatformandladder elevation requirements,Platform flool" space requirements are dictated by op-erator access to controls, instruments, andmaintenance accesses. Exhibits 521 and 522 show platformfloorspacerequirementsforhorizontalandverticalEXHIBIT 519 Typical DrumPlatform Arrangements3. Horizontal Drum Platform Supports99TOPt-'CAp FiZOM b. Vertical Drum Platform Supportsd. Common Platformc. StrUctureLocated Drum100::0-'()\'(\ .1

I-AODCf< :J1alIII

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0rio4

- EXHIBIT S20Horizontal DrumPlatfonn and ladderElevation ReqUirements[IOIIMIN .2S0,.oP'::C'N'I4ETE MAl"" Tlh.lA.... la.M I"I*LoWIi!EWEF'I6.LII6IolIll.ADEBIX&l.liSFIJAJ.,V6H&.b>C>B/ltDRUM INSTRUMENTATIONLevel, pressure, and temperature instruments are usedto comrol theoperation of the drumandshould, beplaced in a position for optimum operation and maintenance. Instrument requirements are usuallyhigh-lightedonaninstrument vessel sketchfurnishedbytheinstrumentengineer assigned totheproject. Ex-hibit 5-29 is a typical instrument vessel sketch.Level controllers, switches, andgauges areeitherlocated individually or grouped froma commonbridle or standpipe. The controller must be operablefrom grade or a platform; switches, gauges, and pres-sureandtemperature connectionsmaybeoperablefromaladder if noplatformisavailableatre-quired elevation.The instrument arrangement shown in Exhibit 5-30wasdeSignedusingthe guidelinesinthis chapter asfollows:The sample piping andinstrumentationdiagramdis-cussed in this chapter is illustrated in Exhibit 5-28. Nozzle locations-Exhibit 5-16. Instrument vessel sketch-Exhibit 5-29... Platform arrangement-Exhibit 5-23.OJ Piping arrangement-Exhibit 5-27. Nozzle summary-Exhibit513.Drum elevation-Exhibit5-12. plant layout specification-Chapter 2.toaconvenient, safelocation. Closedsystemreliefvalves should be located at a convenient platform adja-cent to the drum above the relief valve header. Reliefvalveinlet pipingmorethan20ft (6,100mm) longshould be checked by the systems engineering grouptodeterminewhetherthelinesizeneedstobein-creased for pressure drops. Exhibit 526 shows typicalarrangements for both systems.The piping arrangement shown in Exhibit 527 wasdesigned using the guidelines in this chapter. Thereoquirements can be found as follows: . !"';PIP'lH':.t.TolC:

'"DI'Y.>oIMII.AIZ. XHIBIT 6-16 Typical Horizontal Exchanger Supports118IIiI-!IT"'j.\ IZEMOVAI..

WIT"UTF'I.A1"F=Ol062To P\.A'TFoll""(T.,..P.) To ("TYp,)MA'to..lTe."'A.... G:.PL.ATFORM1-4 EADER 6roxPl..A.TFOI2.MA

123d IBmEXHIBIT 6-24Typical Fixed-PlatformAir Cooler Arrangement124

Pl-ATFo12MFoJ2c::.e.OA.FTc.ooL-ERLADDE-Ii? ToI4E:.AOU .'EXHIBU6-2STypicalTravclingPlatfonn AirCooler Arrangement125EXHffi1T626Considerations forVendor- orContractorSuppfiedSupporting Columnstoredesignthe supportlegs or platforming, causingdelays in delivery and extra costs.NOZZLE ORIENTATIONNozzle orientation andlocation canaffect the piping:;onfigurations at mosl exchanger arrangements. Ade-:lsion bythe piping designer to relocate the ex- nozzlescanoften produceaneatandcost arrangemem. Althoughthepipingdesigner:ioes not have the freedom to independently relocate nozzles, suggestedalternatenozzle loca-ions can bemadeto the exchanger engineer inthemerest of improving external piping arrangements-or example, alternative Bin Exhibit 627 highlights animprovedarrangementby relocating exchanger nozzles. Exhibit628shows allowable nozzle configura-tions.Elbow or gooseneck nozzles are especially usefulinredUcingtheheight of largestackedexchangers.Exhibit 6-29 highlights the effects of using elbow noz-zles on stacked exchangers.Air coolernozzlelocationscanalsoaffectpipingconfigurations. A single-passarrangement canmakethe return piping on an overhead condenser very longandcanalsoincreasetheheightoftheaircooler.Reorienting the air cooler or making the unit a dou-ble-pass arrangement can improve the piping configu-rations. Exhibit 6-30 shows alternative nozzle configu-rations for air cooler piping.126EXHIBIT 627Alternative ArrangementsforLocating ExchangerNozzles'\\ I,ALTEl2tJAi'VE A '\6" a!II i 1: auEXHIBIT 628Allowable NozzleConfigurationsProcess Pla'" Layout andPiping Design7l$lNlAI..TE.r.(,NAT\ VE 'ti.'/S:--...iI-\J;IXCHANGER PIPINGI?QlQ#ALTE.l2.tJAT I \I E 1'6" ,",,01.'%..L5 L.oG.ATION127EXHIBIT 629Effect of Elbow Nozzleson Stacked ExchangersEXHIBIT 630Alternative Air CoolerNozzle Configurations"changerpiping mustberoutedin such a mannerlatit meets economy,flexibility, support, and opera-on andmaintenance accessrequirements. Piping atleU and tube exchangers is positioned to allow ade-uatespacefor removal of channelheadsandshell:)vers. The free space at the side of horizontal shellsan beused for placement of controls. Piping is ele-ated a minimum distance fromgrade or platform tomvide operator headroom clearances, to offer ease,f support,andtomeet designatedpiperack eleva-lions. Large-diameter or moreexpensive piping call"not be set to accommodate smaller or less expensivepiping. Piping connectedto channel head nozzlesshould be furnished with break flanges to facilitate theremoval of the channelhead.Pipingat spiral and plateexchangersis also posi.tioned to allow the opening of covers and the removalof plates. Controls at me spiral exchanger are locatedon the ends of the unit, clear of the cover plate swingarea, andatthefrontandon one sidefortheplate128aEXHIBIT 6-31Piping Arrangement fol"Horizontal Shell andTube Exchangersc:.U&'O:::I( GI.CACZ4fJGe.e:."T '$>uPFbli:T$MAolt-iTEo-Jt..t.ll:e: eoIi:: !at.. to(,\!=LANC:t &.,---I-....l?..,.... PIPIN($l ATEL.SVATIO,,",Tc:::>PiPe:!2.1.i:vAl'ONS A DA'YITexchanger. Pipingiselevatedinafashionsimilartotheshell andtubearrangements. Pipingattachedtothe cover plate nozzles of the spiral units is furnishedwith break flanges. Piping at air coolers is not routedover tubebanks or fansand should be kept dear ofthe designated space for motor maintenance. Exhibits-6-31 through 644 showvarious piping configurationsfor hea,t exchangers.Process Plant Layout andPiping Design VALVE:\';'TE.AM TEE.1.Fl:tAMe TO 'fp ... F"PoR: EXHIBIT 6-37 Piping Arrangement for VerticalReboiler A.Uoy PIPlt-JGrp

:A,.I;"- ---.-.n iIII:1 ' i'I'!I11 . IIII'I,I !IlfI i Ij I,. JI!"I ' ;I :It,I!1.,i I Ir,:r..- -,..-I I,:11 "'. l

II r,,B.. -u '\J-n JI'.....I' '-I P((bVq,e.Loo P'"f'i2.0 VI DE.131EXHIBIT 6-38Piping Arrangement forHighTemperamre,HighPressure FeedExchangers AT C6NTRE XCiC: Ci-lLw-.J t.J f:L.EtooJl' ONLY'''' PIPING r-Otc::FLE; >' Ie,11..1TY" IIALlER-NATIVE 'AI\."J t> E:.FFf::G.T\\JEExcbangen132LOc:..A'i'E PlPIt...sG e:.A"i;lreOF '.'EXHIBIT 6-39Piping Arrangement forFeed Exchangers

COVclZ ARS-A.PWEXHmrr6-4oPiping Arrangement forSpiral ExchangersProcess Plant Layout and PipIng Design !L--"''-'-1~ P I P E : I2.AC K. e::::-ot-UMN ~PLAt.J~ ~ I IIr .,Jr .../ / ~ / ~ELENA.,.' ON133EXHIBIT 6-41Piping Arrangement forPlate ExchangersEXHIBIT 6-42 Air Cooler Piping ConfigurationsU&IFFExchangers&.FFf!G.-r'VEAl TEwA"I\le. JUTIN(:,IF PIPIIoJC::! FLe:'XIf,U=Al-JI) c:..AN '5oPAhJ OI':fJ"A""CE I"I"T&RMe. O'A'TE$uPPoR,EXHIBIT 643Overhead PipingArrangements for:IiCondensing Air Cooler....I

ToLINE134'11I1=012 F=LE)t,If>ILI i"lolE:.Ale G.aOL.EIe(;t:PO-;''''\Ot-lP'N1"TW11oJL.E.T /IJC:l2.2.I.E:-; "'"1=A.2. mUZL.NG ofT"f:. PIPe. fiU'"T"",e-. All2f:>1JiC,110e.lS ... be.A..... !> Tt4-E emNPOTc::> "'T""'EOVEJz,u:..er..p f>lP....46. OUTl..cI PIPINUAI .c..114 CO:::n.E: iZ.pI. .e..TFOIa. M MAINTENANCE.ike an automobileradiator,the internals of heat ex-hangers requireperiodiccleaningandrepair. It ismponant forexchangers andrelated components to>e positioned to facilitate access to their internal pans.For theshell andtubeheat exchangers, thetubesInd theinterior of the shell canbe cleanedinplace\lithhigh-pressuresteamorwaterandroddingde'ices. If the design of the exchanger permits, the lube>undlecanalsoberemovedfor repairorcleaning.tubebundlesandheadandshellcoverscanbereonoved by built-in fixed handling devices (e.g., davits,litch poims, pulling posts), fixed structures with troley beamsandtraveling gantry cranes,or by mobile (e.g., cranes andhydraulic bundle extracors). Exhibits 6-45 through 6-48 provide examples ofube bundle removal eqUipment. Considerable saving beachievedif theplant is selVicedbymobile Air cooler units arenot furnished withfixedhan-135EXHIBIT 644Inlet and Outlet PipingArrangement tor aProduct Air Cooler11= iZe:Qu,k:E: DSUPPola.'T c.oc>LII..IClIloJL.E.T PIPINc::,FJZ,ClMPt.ATFoK'wt'!:oTeE.L.dling devices forremoval of rubebundles, Minor re-pairs(e.g., tubeplugging)areusuallyaccomplishedwith the air cooler in place; for major repairs, aircooler sections are removed by mobile cranes, asshowninExhibit6-49. Internal servicing at plate exchangers can be done manually. In the event of a tubefailure, individual tubes are dosed by inserting a plugthrough the end of the header box and hammering itinto place, as shown in Exhibit 6-50.Theuseof tubebundleextractorseliminates theneed for permanenttube bundleremoval structures,withconsiderable savingtotheplant. Thesemechanisms weigh seven tons and are capable of pull forcesgreater than500,000lbs. Theextractor isliftedintoposition by crane and damped tothe shell flange ofthe exchanger, which is stripped for bundle removal.HeldinpOSitionbythecraneandbalancedbytheextractor's leveling cradle, die bundle is pulled out ofits shell withpullrod attachments that use hydraulicforce. The whole unit is then lowered to grade and canbe reliftedOOlO a truck for off-Site repair or cleaning.':.

EXHIBIT 6-45Bundle Pulling Post

Pu L.L.I""e::. e.cA.MSuNDt!>

EXHIBIT 6-46Fixed Structure With aTrolley BeamI F'IJt.\.\N

+"f"=AM11ZAPt:;;;..

EXHIBIT 733Piping andInstrumentation Diagramfor a Circular FurnaceIIIODD

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Ij.-TO,",l-ACZC:- L.a::::6Te: bTG:!lZt}t:'EO- Mtl.JII.IIUI.I1 '4YIt?-:zooFl20MFU12l-.JllC-C165 Piping andInstrumentation Diagramfor a Combination Burner:'Economic constraints usually determine the feasibilityof thisdesignfeature; all furnaceconfigurations canuse this breeching concept.PIPING lAYOUT FOR A FURNACEThis sectiondetailsthepipinglayout of circular andbox-type furnaces. Althoughsuchspecial featuresassnuffing steam are actually required for both heaters,they are explainedfor one application only.Circular Furnace PipingExhibits 733and 734 present simplifiedpiping andinstrumentationdiagramsfora circular furnace. Thefurnacehas 6ininlet andoutlet lines,withcontrolvalves, combination burners, and soot blowersin theconvection section. The furnace plan and elevation forthe upper level of thiSfurnace are shown in Exhibits7-35 and 7-36, respectively. The stack shown in Exhibit7-36 is equipped with a trolley beam (an optional fea-ture) that pulls the radiant tube bundles during main-tenance. Theneedforplatforms depends onthein-strument requirements. The damper selting isregulated from grade by a cable-operated mechanismsupplied by the furnace vendor. .In the convection section, three stationarysootblowersarefedbyl.5inleadsfromthefiresteamheader located below them. This pipingis kept closeto the convectionsection wall to maximize the available work area for plant personnel. The four 3inproduct inlet lineshavemanual control valvesandlocal flow indicators that must be visible when personnel areoperatingthe valves. They arelocated at theFurnaces166

__ Plan for the Upper Levelof a Circular Furnace167EXHIBIT 7-36Furnace ElevatiOn fortheUpperI.evel of a CircularFurnace

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168EXHIBIT 7-37Lower PIan for a CircularFumacef

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DUTL.e:T..----------fIJSL. c:olLupper platform for economic reasons-placing themat grade wouldrequire runningfourindividuallinesuptheentirefurnace. Thesnuffingsteamlinesaregrouped together for common support until theyreachthetOP of theradiant section. Theline totheheader box on the opposite side is run radially aroundthe heater. Bending smallll.nes is generally not aproblemandsaves fittings andwelds. Platforms arede-signedtopermit plant operationsandmaintenancepersonnel dearaccess toaU valves, instruments, andsootThe lower level of the circular furnaceis shown inExhibits 7-37 through 7-39. In theradiant section, allpiping should be grouped together for common sup-Pro4;ess plant Layout and PIping Designport when praCtical, as shown in Exhibit 7-38.Snuffing steam, which is used to suppress a fire inthe header box in the convection or radiant sections,is supplied through local andremote manifolds. Theremote manifold shoulAbe no closer than SO ft(15,000mm) fromthefurnace. InExhibit 7-37, thelocal manifold is located at grade, next to the interme-diate pipe support column. If the local area is unreachable in an emergency, steam would be supplied fromthe remote manifold. The inlet and outlet control sta"dons arelocated along the piperack adjacenttothefurnace. Thisparticularfurnaceuses manuallycon-trolledvalves for each burner. The burner supplyheaders-fuel gas, firesteam, and fuel oil-arerun169EXmBIT7-38Furnace Elevation for theLower Level of a CircularFurnaceFUi:L ----

II FUa. 0' L ---I-...;..a....IFunuacesEXHIBIT 739Burner Piping Detail170@-----e9=EXHIBIT 7-40Piping andInstmmentation Diagramfor a Box-Type Furnaceradially over one another to keep theladder close tothe furnace wall. This positioning also allows the indi- .vidual burner piping leads to run adjacent to me peepdoors, creating access to the valves during operation,as shown in Exhibit 739. The pHO[ gas valve is locatedbelow the furnace, providing operator access duringignition. It shouldbenotedthat althoughmost newfurnace installations use burner management systems,this designapproachisacceptable if manual controland ignition is required.The fueloH, fuelgas, and pilot gascontrolvalvesare located at thepipe rack. The fuelgasis run sym-metrically to provide an even gas flow to each burner.This system must be kept dry by the elimination of lowpoints where condensate maycollect. The headerProcess PIa."t Layout and Piping Designshould have adriplegtoremove anycondensatebuild-up by piping it to the flare system. The fire steamlinethat atomizessteammust berunandinsulatedwith the fuel oil line to decrease oil Viscosity. Atomiz-ing steamis injected into the burner with the fuel oilto obtain effective combustion.Theheader-boxdrainmusthavea seal loopandclean-mit plug for inspection just above the drain hub(seeExhibit 7-37). Removal of thisplugpermitsin-spectionfor small leaks inthetubeheaders intheheader box.The 360" firing platform allows fullaccess aroundtheradiant sectiontotheburner valves (at thepeepdoors) and instruments. The intermediate platform isfurnishedtomeet OSHAreqUirements, whichstate171EmmIT 7-41Box-Type Furnacef, the steam being generated.Steamreturnsto thetopportionof thedrum, whilethe water lines come off the bottom. Loops and pock-ets must be avoided when laying out the downcomer,and riser piping and any horizontallines must slopetoward the waste heat boiler or convection coil. Whenpumps are used in this circuit, it is called forced circu-lation.Transfer line exchanger piping is shown in Exhibit7-49. This exampleshows howtheheated productoutlet of a pyrolysis furnace isu s ~ d to generate steam.Themain considerationis the downcomer andriserpiping between the steam drum and transfer line ex-changers. Lines shouldbe runwithapronouncedslope to avoidundesirable slug flow, whichtendstooccur in horizontal pipingruns. Vertical expansion. loops can be easily spring-supported fromthe struc-ture. The transfer line exchanger is supported by t'WOlugs just above the bottom channel flange,and a trol-ley beam is provided to remove the top head for main-tenance. Inthissystem, theproduct lineenterstheEXHIBIT 7-49 Transfer Line Exchanger Piping&NO vieWconvectionsection, exits thecoil intothecrossoverpiping, and then enters the radiant tubes through thetop of theh e a t e r ~ The heated product outlet from thetwo rows of radiant tubes enters the transfer lineex-changer from the bonom, transferring its excess heatenergy to the steam piping, and exits at the top of theexchanger.177TAIL GAS INCINERATOR ANDWASTE HEAT UNITWaste gases containing liquids that must be disposedof and that for environmental or safety reasons cannerbe directed to the flare system arc burned in a tail gasincinerator, shown in Exhibit 750. The horizontal inFurnaces178SfEXHIBIT 7-50Tail Gas Incineratorcinerator is bolted directlyto the stack. Thewasteproduct entersthetopinletandisdisposedof byaburner firing directly imo the chamber. Piping usuallyassociated with this equipment includes fuel gas, pilotgas, steam, nitrogen, and a liquid drain outlet locatedin the stack.The waste heatrecovery unit, illustrated in Exhibit7.51, uses the waste gases of 8000to 1,2000F (4250to6500C) from a gas turbine to generate high. and low-pressuresteamfor plant use. Ascan beseeninthisexhibit, duct burnerslocatedintheinlet of thisunitcanbe used if the turbineis shut down, providing' aProcess Plant Layout andPiping Designcontinuedheat source for steamgeneration. Becausethe physical makeup of these waste heat units varies insize and overall configuration, a derailed pipip.g layoutis not shown.Because the configuration of equipment and associateditemscoveredin thischapter mayvarysignifi-cantly among vendors, the plant layout designershouldstudy theprinciples outlined and adjusteachlayout accordingly. Consideration for maintenance,operation, safety, and economics, as well as the use ofcommon sense, resu){sinan effective overallfurnacedesign.EXHmIT 7S1 Waste Heat Recovery Unit179 if.l}oell..G:fZ. WA'bTE::' l-If;"bT UNITFunuu:es ,>CHAPTERThis chapter highlights the types of pumps commonlyfound in industrial plants, along with maintenance andoperationconsiderationsfor acenrrifugal pumppip-inglayour.Exhibit 81 shows:melectricmotor-drivenhorizontal pump thatis familiartoplant layout designers.Thetwoprimarypipingconnenionsarethesuctionanddischarge nozzles(i.e., liqUid inlet andoutlet).Theimpellttrwithinthepump case drawstheliquidinto the pump and sendsit out at a highvelocity. Theimpeller shaft is sealedwitha Sluffingbox wheretheshaft exits thecase lOprevent thepumpfluid fromleaking. Drips from wearing seals are picked up in theSlUffing hox drain. The pump shan is connected to thedriveshaft byacoupling, which isenclosedwithinprotective housing. Both pump and driver aremounted on a common baseplate. Miscellaneouspumpleaks that collect withinthe baseplmeduringoperationare drained through a connection at thefrom of thepump.Pump size and configuration vary for the folloWingreasons:.. The commodity being pumped... The viscosity of theliquid... Capacity... Pressure... Temperature... Availableheadrequirements... Physical limitations.Initial pump piping layouts are done withprelimi-naryinformation. TheeqUipment engineersuppliesthe plant layout designer with a catalogcut ofthepump that most closely represents the one to he pur-chased. Inmany cases. this data doesnot change sig-nlfiC',mtly if the engineer hasmadethecorrect selec-tion. Piping layouts are started early ill the study phase;when the certified vendor dwwings become llvailablelater in theproject, minor adjustmentsaremadeasPumpsreqUired.Dimensions of nozzle locations or baseplatesizes maychangeslightly, but revisions to phYSicalnozzle locations (i.e., from(OP to side or side to front)do not usually occur when the data is finalized. Working dosely with the eqUipment and system engineersacquaints theprincipal partieswiththeexact designconditions andminin1izesrework.r,PUMP TERMINOLOGYThis section highlights someofthe most commonterms that the plamlayout designer encounterSw h ~ ncreating a pumplayout.Allowable nozzle loading The allow'lble nozzleloading is the maximum amount of stress thm the pip-ingconfigurationmayimposeonthepumpsuctionand dischargeno:r.zles, as setby rhe vendor, client, Ofcode. The pipe stress engineer is respollsible forworking within this tolerance by coordinating the pip-ing design early in a project and rechecking all calcula-tions before formal fabricationL'iSUeS of piping dmw-ings aremade.Netpositive suction head NPSHis one of rhe mostimportant termsa plant layout designerneedstoun-derstand whendevelopinganeqUipment layoutthmincludes pumps and vessels. The reqUired nel positivesuction head is a measure of the pressure drop of theliquidasit movesfromtheinlet of thepumptotheeye of theimpeller. It is a dluraCleristic of the pump(hat is generallydetermined bytesting and is ex-pressed in"feet of water" by the pump manufacturer.Vapor pressure When the pressure in the pump suc-tion line falls below the vapor pressure of a liquid, theliqUidflashes,or changestoV'Jpor. Becuuse no ordi-nary liquid pump C'JI1 pump only vapor; liqUid flow tothepumpfalls off and the unit issaidtobevaporbound.181182EXHIBIT 8-1CentrifugalPump'\4?k!pl..INei! 4tUAlZ'2 ~ ~ l . A r e ~ l - Jb1Uff:I!:k2ee)(!?CZAItJAvailablenet positive suction head The availablt:NPSHis thenet prc:ssure :Jvailable in a givensystem,based onvessel pressure andstatichead, minustheliquid vapor pressure and functionallosses inthe sys-.tern. Thegoal istomaintainequipment heightsandminimi:le pump suction piping toensure that theavailable NPSHis greater than the required NPSH. In-sufficient NPSHcan reducepumpcapacityandeffi-ciency and lead ro cavitation damage.Cavitation Therapid collapse of vapor hubbies thatcan produce noise, result in a loss of head and capac-ity, andcreatea severeerosion of theimpellerandtftute, outlinesseveral pumps with standard dimensions. They are in-terchangeable for a given size, regardless of whobuilds the pump, with no effect on foundation, pipingdesign, or type of electric motor used.NPSH REQUIREMENTSAn example of how to deal with a typicalNPSH prob-lem is shown in Exhibit 8-2. The reqUired NPSH in thisexampleis22ft (6,700 mm). If ahorizontalpumpisused, thebonomtangent line of vesselA must beaminimum of 22ft (6,700mm)abovethecenterlineelevation of the shaft. If a verticalpumpisused, the..... _.. ~...-181.EXHIBIT 82NPSHExamplevessel Btangent line is located closer to grade heGllIseNIJSHis calculatedfromthebottomimpeller of thepump locatedbelow grade. Althoughvenical pumpsrequire less of a vessel support structure~ l I l d possihlyless piping, they are more expensive to huy and main-win. Therefore, ahorizontal pumpapplicmion is tlmore desirable solution in this instance. Venicalpumps are better used todrawsuction fromlargesurface coodensors thatservicelarge compressors.lYPES OF PUMPSPumps are classifiedascentrifugal, positive displace-ment (reciproc.uing), or rotary.Centrifugal PumpsThe majority of pumps used in industry are centrifugalbecause of their flexibility in flow rates, pressure, andtemperature.They areusually drivenby electricmo-torsorsteamturhines. Theymayhesinglestageormultistage, dependingonpressure requirements inthe system, and can be horizontal or vertiC'205EXHIBIT 94Process Vessel Sketcb0- 00_t'IN02.2LE. size$IERVIGEAe1/ h.a"JeGTICN/ e:.r ..t=:tAITf"'OeWlp. t.Jo2.2.L.e(;') UTL.e,..

EXHIBIT Spherical Reactor217EXHIBIT 9-28Horizontal Reactorl1eunloadingnozzle, thecatalystcanbeallowedtoreefall toa 'temporarycontainment areaorhere-novedusinganindustrial vacuum, or atemporaryalve may be used to control theunloading rates. Ex-lihiLS 9-27 through 930 are examples of less commoneactor arrangements.Thedimensions, clearances, andguidelines high-lighted in this chapter are examples of reactor arrangements. The plant layout designer, however,should be familiar with company and c1iem standardsbefore proceeding with reactor layout and should ).ordinate thiseffort withsuchsupportinggroups asvessel, systems, process, civil, and instrument engineering.Reactors218EXlUBIT 9-29 Stacked Reactors EXHIBIT 9-30 Multibed Reactor

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6(;:.6o"'I>./.. T /oo,JO'1'Z.LE:-OUTLETNo2.'Z.l-E:: Process Pia,,' laYOut and Piping DmgnCHAPTERTowers, alsoreferredtoascolumns, areoneof theprincipal pieces of equipment of any processing facil-ity. Towers arecylindrical steelvessels thatareusedfordistilling raw materialsinthe production of suchproducts as gasoline, diesel, and heating oil. The plantlayout designer must undersrand the internal structureof a tower andhowit operates toproduce a satisfac-tory design...This chapter highlights thegeneral requirementsfor tower plant layout design. It describes the internalworkings of towersandprovidestheinformationre-qUiredtoorient nozzles; locateinstruments, piping,andcontrols; andprOVideplatformsandladdersforoperator and maintenance access.THE DISTILLATION PROCESSCrude oil is of linle commercial use; when separated,orbrokendown, however, oil becomesoneof themost valuable commodities in the world. Crude oil is amixture of hydrocarbon compounds with a widerange of boiling points from100 F (38 C) to 1,400 F(760 C).Separation, or distillation,isa processby which aliqUidmixtureispartially vaporized. Thevaporsarethen condensed, separating the individual compo-nents of the mixture. N, the temperature of crude oil israised, theinitial boilingpOint(rap)is reached. Asboiling continues, me temperature rises. The lightestmaterial, burane,. isproducedfirst, at IBP, just below100 F (38 C); the heavier materials are produced below 800 F (427 C). Theresidueincludes everythingabove 800 F (427 C). Exhibit 10-1 shows the distribu-tion of the different products at me various tempera-ture ranges.The evolution of distillation towers is best ex-plained in three basic steps: The batch shell still process., The continuous shell still process.Towers The fractionaldistillation process.Batch ShellIn the hatch shell stiII process, the still is panially filledwith a set feed called a batch. The feed is then heatedtothe temperature requiredto produceaspecificproduct fromtheoverhead vapors. This process isrepeatedeachtimeforeachproduct until the? batchreaches themaximumtemperaturefor therangeofproducts specified. The feedremainingin the still isthen pumped out, and the still is allowed to cool. It isthenrefilled, and the whole process isrepeated. Notonly is this process time consuming, but the product isnot always ofhigh quality. Exhibit 10-2shows thebatch shell still process, which was one of the earliestused for liquidmixture separation.Continuous ShellIn the continuous shell still process, several shell stillsare linked in series to form a battery. Fresh feed con-tinuously enters the first still, which is kept at the low-est temperature for the lightest overhead product. Thebottoms fromthe first still are fed to the second still,which is kept at the temperature for the next highestboiling overhead product. and so on. The number ofstills reqUireddependsonthe number of productsneeded. If the feedandthe temperature of each stillremain constant. the finished product is of satisfactoryquality. Exhibit 10-3 depicts the continuous shell stillprocess, which is an improvement over the batch shellstill operation.Fractional DistillationSimilar to the continuous shell still, the fractional dis-tillationprocess is made upof several stillslinkedtogether in series. The main difference is that alltheliqUid condensate is returned to the upstream still. Asthe feedis partially vaporized inthe first still, the va-219220EXHIBIT 101 Crude Distillation of Products AcrossTemperature RangeEXHIBIT 10-2 Batch Shell Still Distillation Pl:ocessc.oNDEflJ$E.f::Sr!;GOMD~~ ~ ~Fe-aDpors rise, travel through the overhead line, and comeinto contact with the liquid in the second still. Becausethetemperatureof theliquidinthesecondstill islower than the incoming vapors from the first still, thevaporspartiallycondense. At thesametime, liqUidfromthe second stillenters near the top of thefirstEXHIBIT 103Continuous Shell StillDistillation ProcessEXHIBIT 10-4Multiunit FractionalDistillation ProcessP2.0puc;..T15t"F( h e ~ )still. As vapors rise in the first still, they meet theitcoming liqUid from the second still. This causes vapOlizationof theincoming liqUid fromthesecondsti;and condensation of the rising vapors in the first stUThe samereaction takes place in all the downstrear:stiUs. This process improves on previous operations iljsaEXHIBIT 105 Fractionator Towertermsof quantity, quality, andareductionin the en-ergyneededtoheat the I"J.Wmaterials. Exhibit 10-4 "illustrates themultiunit fractionaldistillation process.All three process arrangements are satisfactory op-erationsandplayanimportantpart inthedevelop-nent of the modern distillation tower. The final stepn combining these operations into one single compo-"lent is achievedby slackingthe stills on top of each)ther andinstaIling aninternal devicebetween eachitill to allowthe liquid to flow down and the vapors toise. This means that the single unit can functionin a'lay similar to memultishellunit forless capital and)perational cost Exhibit }Q..5 shows a single fractionaortOWer withthe corresponding stillnumbersandemperaturerangesof themultistill unit. 11lereflux"eturnlinecontrols thetemperature of thefluidsinhe upper portion of the tower.rapor and liquid Flow)ne of the most common internal devices that allows~ e single tower to function similarly to the multistillInitisthetray, illustrated inExhibit 106. Slots anddes in the trays allow the vapor to rise and the liquid221EXHmlT 106 Vapor Liquid Flowto flowdown.Risingvapors in the tower pass through s l o t t ~ dbubble caps and come into contact with liqUid flowingaround the caps. liqUid flowing downfromtraysabove fallthrough downcomers and over and aroundthe bubble caps enroute to the next downcomer. Inthismanner, the light boiling fractionsin the down-flOWing liquid are vaporized by the heat fromthe ris-ing vapors, and heavier boiling fractions in the vaporare condensed and flow down the tower. This processof vaporizingandcondensingthroughout thetowerallows the feed to be separated into the required hoil-ing-range fractions, which are drawn offfrom the sideof the tower at the appropriate locations. 'TYPES OF TOWERSTowers are named for the service or type of unit theyare associated with. For example, a stripper is used tostrip lighter material from the bottoms of a main toweror avacuum tower. It is generally used in a vacuum!crude unit fordistilling crude bottoms residue underTowers222EXHIBIT 10-' Vacuum Tower and Stripper EXHIBIT 10-8 Trayed TowerVAcwwMLeVISL.

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!viA 14"--1:,.,I... !: rLI:: :;I.--j:: 1vacuum pressure. Exhibit 10-7 shows a typical vacuumtOwer and stripper.From the outside, tower configurations are similarin appearance, varying only in dimension; some tow-ers have swaged top and bottom sections. The princi-pal difference among towers is the type and layout ofthe internal components that control the vapor-liquidcontact.This chapter describes the internal andexternalplant layout requirements forthe two most commontypes of tower:thetrayedandpacked arrangements.Exhibit 10-8 depicts a typical teayed tower with someof irs associated components.In a packed tower, instead of having trays, the unitsare packed with beds of metal rings. On e.ntering thetower, the liqUid passes through a distributor thatroutesthe liquidevenlydownthrough thepackedbeds of metal rings. Rising vapors passing through thebeds come into contact with the descending liqUid. Ina manner similar to trayed tower operation, the liquidis partially vaporized by the heat from the vapors andthe vapors are condensed by the cooler liquid. Exhibit10-9illustratesatypical gas-liqUid packed tower andirs principal components./..,,"mIT 10-9 Packed TowerI..IQIoJID c..E: CONSIDERATIONSOR TOWERSowers are not a standalone operation; they are usu-.ly located withina process unit adjacent torelated and in a suitable position for operator andlaintenanceaccess. A toweroperatesdosetosuchitemsaspumps, reboilers, drums, andcon-ensers and shouldbe positioned to facilitatean or-edyand economicinterconnectionbetween itselfld that equipment.Within the conventional inline process unit, towers223and their related items are located on either side of acentral pipe rack, serviced by auxiliary roads for main-tenance access. Inplants in which therelatedeqUip-ment is housed, the tower is often located adjacent tothebuilding orstructurecontainingtheequipment.Exhibit 10-10 shows a process flow diagram of a towerand ils related equipment, a typical plan arrangementof the same equipment, andthe equipment in eleva-tioo. ,/'TOWER ELEVATION AND SUPPORTTower elevation is the distance from grade to the bot-tom tangent line of the vessel. Support is the means bywhich the vessel is retained at the required elevation.Exhibit 10-11 shows an example of elevation and sup-port.Although tower elevation must satisfyminimumNPSH requirements, it can be set by a combination ofthe follOWing constraints-whichever produces theminimum tangent line elevation:III NPSH (Exhibit 10-12).III Operator access (Exhibit 10-13).GO Maintenance access (Exhibit 10-14).III Minimum clearance (Exhibit 10-15). Verticalreboiler (Exhibit 10-16).III Common access (Exhibit 10-17).Askirt is the most frequently used andmost satis-factorymeans of supponforvertical vessels. It is attachedby continuous welding to the bottomhead ofthe vessel andis furnished with a base ring, whichissecured to a concrete foundation or structural frameby means of anchor bolts. Inmost cases, theskirtisstraight, but ontall, small-diameter towers, theskirtcould be flared. Access openings are reqUired in ves-sel skirts for inspectiOn and, when possible, should beorientedtowardthemainaccessway. Exhibit 10-18shows a typical skirt arrangement.224 I ..q:;:::::;:. ==t. I -=-1.1!Gt