Project Engineering of Process Plants

Project Engineering of Process Plants

(Parte 7 de 10)

Labur regulations, la~~-s. :ml incor~le tascs or otlicr labor taxes slrould inve;tigated and fully underat~~od. In certain countries lnhor rcguln- tions may also affect expatriate pcrwnnel. Any such lam or regulations nrurt be explained to expatriate personnel at the time of hiring. On large ~wojects it is often conunon practice to institute training prugranis so that the nalirmnls can become skilled in the varioui crafts. Courtrurticm personnel hiring for foreign operations is usually an in- vulved process. All pcrsmnrl so hired sl~ould be employed under a rrontract for :I certain number of n~ontlri. A bonus is frequently offercd :IS an incentiw to cou~plete the projevt. All personnel sliould be subjected to a physical examination and all licccssary vaccinations taken to mect the rcquire~ilents of the particular area.

If the project is remote from a metropolitan area, medical facilities .lrould he provided. It is sometimes possible tu erect so~tic of t,he perma- IIVII~ tmilding* enrly in the project. In such instanres facilities for a cer- tain amount of lro~pitalizatinn can be prorided during the construction ~wriod. In tl~? ~~riuii(ive countrie? medii~al s~rpplies are 11ftc11 uriol~tai~iable.

Provisions niust he made to provide adequate ~rrcdical supplics for all em- 11loyrrl perso~nel, both nationals as well as cxpatriatc:: since many of the muntries require that an cniployer (particularly foreign) nus st proride iiicclical attention for all eml~loyees regar~llcss of their nntional origin. Furtl~ertnore, tlic costs are lregligible cunlpared to the possible ill-will gmcratrii if 111edica1 care is not supplied.

T.S. cxpatriatw tnnst ol~tnin a passport and the proper vim ~I the rqrwmtatirer. of tl~e country to bc vikiteil. To obtain :i F.S. lxiss- tlic. person IIIS~ pro~e his U.S. citizcnal~ip by I~irtll certifiwtt, or :~fii<l:tvit: he nit14 hare a heal police release and usually a letter from the e~~qiloycr stating the reason for the rid. ('r.rt;~in couuirirs restrict alrd liluit tl~v i~~ui~utrt of pewo~~al effw1s

\\-Irirl~ may be carriwl by personnel. 3I;rny cmuitries rrquire payment of duties on pcrsontxl effects sueh as shoes and clothing if they are nrm ;~nd

I-d Thew requirenrcnta should he ascertained and put inti1 [irintcd form so that they can be untlerstooil rompletely.

\1:11iy 1~1~1y~~1.s 1111y t~.:~vel or (C~I it~s~t~i~~rw of OIIC I~imI :tnot11c1,

42 Project Engineering of Process Plants

\vithout iwt to the employee. payahle to the ~mploycc's hcnefiriary in I.;IW cli (ltxtl~ or injury. This procedure is a good niorale huilclcr and is not an inqxxtant rust item. It is important that personnel housing he adequate. All iurnishings

~l~oolcl bc of n good d~~rahlc qriality and food sl~ould meet U.S. standartk (:ood housing and food is an important asset to any iorcign project.

Si~thing can affect n~orwlc, so seriously as uncomfortal~lc living conditic~ns cx poor food. Savings in follcl coats cannot possibly approach personnel transl~ortation costs caused by a high lahor turnover.

A ircqucnt prohlcm with expatriate personnel on extended foreign proje<,ts is the qucstion of single-status rs. family-status. If housing

~nmt be provided, tlic nu~uber of employees pennitteil to take their fw~nilies may hecon~c an important cost item. It is the practice at times on foreign projccts to allon key co~~rtruction personnel to more their fa~nilicr to tllc locality. At times it is also com~nc~n practice to permit rn~ploynicr~t only 1 a single-status Lasir. These proccdurcs and prac- tires yary wnriclcrably ~rith ovners and construction firnis and are also g~lvcl.neil 11y tlrc local conditions. A11 such points inust 11c dcrelope(l and iliould bc ir~clr~,led in the printed form or tl~c coz~tract with the employee.

1. I.rcming, J., Jjoiicin Espo,-t Pocking, TI& Prornntional Swirn So. 207. Bureau 71 Furrign and Domustie Cammcl.ce, D~pt. oi Cu~nmc~.e, IVashinpton. D.C., 1940.

CHAPTER 4

Process engineering is concerned nith the devclopn~cnt. craluation, and design of cl~eniical processes. Pcrliaps in no other phase of rlien~iral mginrcring can tl~c engineer better npply the technical knowledge anll skill gained in his formal college education. Altl~l~ugl~ mmy operating conq~ar~iea may departmentalize proccss cnginccring into development. wonm~ie analysis, and design, it is not uncommon for a single 11roi~~i:

engineer to originate a new process and follm~ it tliruugh the dc5ipr1 stages to a con~plcted jilant. Indeed. many prore?s engineers ~ith uln- sidcrable cxpcricnce arc called upon to direct tl~c design of a nc~ pl:mt ns project engineers on the Iiasis of their intimate knolvlcdge of thr

Inwcess. Thc complete discussion of process engineering and particularly of

Ilrocess design n-onlrl rcqrrirr a book i~f eondrrable length. Crrtai~~ l~ricf conmicnts, however, concerning the rariws phase.; of proccss en- gineering \vill aid in integrating it into t~c overall plant design pirtnre.

Fundamental research in chemistry and cl~erriicnl cnginccring is per- fornied to a large degree in the laboratories of universities and privately cndoaeil rescarch institutes. Many of the procc?r industries, Iio~r-ever. and a number of design firms have found it necessary to conduct certain types of funclamental researcll. It is the indnetrinl-typc fundanientnl re- search that pertains to this discussim

4 Project Engineering of Process Plants

XI,\\ ],~.o,lucl- ;iri, ol'tc~l INI~I ill tl~e l~i::~k,~rs :~n(i Ic-t t1111c'. of 1.11w11i-t?

1 irullt-trial lalmratiries vhen stnil?-ing certain types oi rcv.?tiuni tn gmn iunrl;~n~cntal 1inon.lcdge in n~ucli the same manner as the clicniist~ at a nniv~,rbity or r~.,e;rrch institote. The difiermce is tl1:1 the inilrlstrial clrr.ni~d cli~~ows reactions t1i;lt. if sl~cce.:ful. havp wme i~n~:~cdiate eoln- ~wrrial siprifir.;~nvc.

1, cl~f.i~~ic;~l CIRII,CI! ;ilro i- ~,ngi~gc(I ill I!IW:I!I,~I f~~n(Ii~n~~'nt:~l to his

I~I Ileny emnl~:lnics carry out r~,ntinl~ous t,xpcri1nent21l programs

1 unit olwralions, rc.:irti,in killrtiri. ;inii t~lerl~lo~iyonlllic~. The lIllr110s~' oi m41 C~~I~>~~I~!I~:I~~I iq to gxi11 a g~.r;~tw k110~1cdg~~ of these operation.. so t11;lt <lcsign l~roce~li~rrs anll phnt 11pcratinl1 r;ln he inl~lruvcl~.

('l~eniiral in~lrritry vannot priigres vitl~out a continr~uus ,supl~ly of nen- Fl~n~la~iicntnl kn,ir\-ledge and iniornlation. The twrly An~czrican chemical inrlustry r~htained 1nur.1 f~~n~l:i~ncntal lino~i'ledge from Earope, particularly in the field ui pnrc eircn~istry. Ilorr and mim. ho\vewr, hnlericnn univ?rsitie, research institutes, and in~lustrial lahratoriei arc inrnishirlg fundamental research nrccisary ior the growtli of the proress industries.

Congre.s 1,-tahli.hecI Tiic Satio11:ti Frienw 1:onndation to enmurape the ~lcvcl~,pnent ,,i fund:rmmtal resc;tr,.l activities in tlte Lnitcil Stntw

A roni]~etent pruccss enpinecr must ~uaintain inti~ili~tc, c11nt:ict ~i'itlr rlerelopr~~entr of fundnn~r~ntal knowledge in his l~;irticular field. He docs this by periwlical review of the literature and by close asbociation xith rrorlc progressing in his ,Inn orgnnizatim.

Process Development

Sen' ~lesign princil~lc.s, novel re:lction; and nen' cornpinul~ls ui.uZIll?.

suggest applications oi industrial importanre to alert tr~,llnical nmnwgr- mmt. Snch applications may he a new proccsr; or the i~n[~rovclucnt IIE an existing OM,. hot11 of rvhich rqnirc tht! design an11 cun~truction c~f ncn- facilities an11 nlay involve ~,xpcnditures of several niillion ilollnrs. Sinw so 111r1cl1 of engineering design is of an empirical nature. it is seldom 110s- sil,lc to j~nnp irom the heaker to the finished plant. h considcrablc amount ui what might hr called applied derclopmentnl research mn~t he ilonc. Tlic intormiltion obtained penuit~ the design of [lrocess equip~nent with n rcasimahlc ~rno~int oi assurance. The process engineer \rho xill be concerned n.it11 the design and prllaljs the ultimate operati~~n of a ~xoccs~ hccinnes intimately associated nit11 the study at this point. He

~lioi~ld he supplied ~7-itl1 ail data nnd interpretations ol data obtaincd in the lah~atr. His i~ackground of plant design and operation n~nke hi? counsel extren~ely valuable to the devrloplicntal groups. The prnces er~zincer can he nssureil of haring all posihl~~ rhte necessary ior design ri~l~wli~tions only if IIC. 1:iintnins a clo>c Ii;li-uo n-it11 ~hr poews 11rvelop-

~nint dt>l~:~~'tn~~~t.

Process Engineering 45

Procc.>- der-elol~n~mt often hegins xith a bend-scale 1aI1or:itory stud>-.

Sn~nll-ccale yi:ia, or ~nctal ~~r~uii~n~ent is c~llpl~~ycd ti, ollt:~in rlatn ilf 2111 ~xploratory nature. hell cxpcri~l~cntation is ~-aIuahle ;incc it is oiten an iilcxlm~sive means of proving the fwsil)ility of a process and of ilirccti~~:: the n-:iy tu fl~rthcr rcsmrrh efforts. The extent of chemical cnginecri~rg kno~r-ledge at the llresrnt time scl,lom per~nit~ the design of a lien- plant from bench scale lahorntory data alone. Tllrro are yo many unk11on.n-

;lnd intaugihles n.liich hare defied tllc.orrtiral annlysi? tila1 it i- new:w'y tu emluate these iactors cnlpirically on larger xalc c~~r~i~~~l~cnt. ~r~-cnllc~l pilot plant or semi-plant equipment. In pilot plant and semi-plant o11rr;l- tiun n procedure as nearly like that. dliel~ n.iU hc e111~10yed in th~. caul- nlercial plant is follon.cd so that the d;~t;l ~~lltaincii can he used n-it11 cu~~fiilence in the araling up of the l~ilot plant to ~,o~nnierci:il six

Pilot plants are costly to bnild and operate. It is not ilnciitnnvm fur :I single. pilot ljlant to cost clusc to a inillion dollars. It is. tl~erciorc.

inil~erativc that all tl~corctical knou.lcdge ;~railablc ta the clhc~nic;:l engincer he used to rednre the anlount of pilot plant ~ork requirerl and. if l~~siblc, climin:rtc it entirely. It is pu~sil~lv. for instance, to ol~tain rcaction rate (latn for a new reactiln on sill~~k h~m~~l-s~ak cqlijllt~lt.

I-sing the principles of applied kinetirs, rate erj~~ations can then be ilr- reloped ~vhich dl ])ennit the calculation of reactor size for a nlnnher oi

<lifferent conditions of ol~eratiou enahling the choicc oi the iilost crw 1m1ie:1 design ix-ith the niininluni a~:~ount oi exp~rit~~cntal diitil. It I:I!.

itill he cmsidcrcd x!-isc in sn1.1 a casc to oper;rte :I pilut p1:tnt for tllc p~irposc uf ohtaining corrosion data, heat transfer inior~natiun, and general operating charaeteristics oi the prirccss. The kno~lcilgc oi kinetics gained in the brnrli-scale operation ~~uld aid gently in tilt,

<lr.sign of the 11ilot plant and x-ould indicate very definitely the luinimu~n aniount of data required. The al~plication of thcoretiral knowledge in t,lrii fashion saves a, great deal of time and expense and is far superior to the c~~mplctel?- cnlpirical approach of "let's try this to~l:~y."

.%lthongh the empirical n~etliud of rc~cmch has been ;uccc>sful in the dcxlolxnent of the process inrlustries, a wntinuous cffurt inr~st IIC, 1na11c to strengthen the thcnretical harkgro~md of the various unit uper:ition-

>o that more and nrorc resnlts may lw cnlculated, thoeby reilucing or clin~inating completely niuch of the pilot plant and semi-plant rrork no~v required.

Process evaluation consists of both an engineering and cconomic analysis of a process and in thc broadest sense is a rontinoing oper;ttion. It ,sho1(1 Ile sta~,t,,~l ,.vr.1 I~efor,, :iny l:ihu~~:~t~~~y \!~!c~rl< IISI> 1wc.1 101r. A c;~rciul annlvsis oi co:t nt :in early st:~gc \!'ill incli~,atc, if the l)rol,esc pro-

46 Project Engineering of Process Plants posed has protiii?e and may :rlso suggest the direction of experimentation. Process er;rluation slluuld c,~ntinuc at regulilr iutervals as significant and nclv data are uncovered. This continuous recraluation of the cngiuecri~~g and cconouiic factors in the ~~rul~os~d process aids in the overall pianniug I I;cuch-scale and ~~ilot plant 1-ork Tl~err nre ift ten nlnny !\-a>-. of ar~c~rm~~lishing a given unit operation, Ililt thrse pwsihilities ran be rcstrirtcd to only a lev n-hen economics is considcrcd. Dybdal? has presented the relation of project evaluation to veil-planned experin~ental 1-ork, particularly tlrr planning that occurs I~ctrveen laburntory and 11ilot 11l:mt lvork. One of the ICSS tangillle factors in favor oi procrss eraluation at thi~ stngr is that making :I cwt estimate requires knoll-ledge of tilt, cqui~iuicnt to 11c cniployrtl and, t,l~erefore: automatically forces the chemical engineer to think objcctirely. Such thinking inevitably suggrsts nxmy itelus of inforumtion that sl~oulcl be obtained from the pilot p1:iut ol~eriition.

Tlic type of ,,I.~ cstinuite requirrli for tilt! studit+ thus Ear ~nentioncd is termed the predcsign cost rstiu~~tc since it is 11ad only 011 information that is available prior to the actual design 11f plant equipment. The pre- design estiniate is not only \duahlc in that it rlirccts research projects into the rnwt profitable paths, but it is also ;I very real aid in design cnlculations. .Is the p~or~?s drsign of a plant procccils, alternate Ineans of oprratirm for portions of the 11lnnt often l~wome aplxu'cnt. Various

;irrangcul~nts of heat excl~nr~gcr;;, prrsrure or teulllcraturr of reactllrs, ad operating pressure:: uf ni)sorhors are typical of tl~e factors to be con- sidered in alternate designs.

Cost estiniating does not cnd xlien the drririon to build a plant is ruade.

Itquirics arc sent to various contr:~cturs, and they must make preliminary design calculations and obtain quotations on thosc item of equipment for lvliicl~ they have little or nil recent cost data. From this information contractors develo11 prelimi~iary cost cstirnates upon xhicl~ thrir bids are based. If tl~r conlrncti~r n~alies :I fir111 q~~~~tation. I~is rust an:llysis uiust he exceedingly ~neticulou arid c~ntin~rncies must he krpt as lor%. as pi~ssible to insure the lvinniug of the contract. $wcalled cost plus con- tracts, diich are usually pupular during nccelcrwtcd building programs tyl~ical of var-time periods. 11rotcct the contrnctor from the many incnl- culable vr~ntiugencirs ~vliich ;~lw;tys aribe, in rush projects that ent:iil considerablr risks. As the design ;in11 construrtim rv11r1~ on pr~jccts prorcd~. thc custoli~er uru:illy rtqi~csts nc5v r-tin~atvs of the ultimate cost enrh montll ur for suuic othcr mu\.cnii~nl iutrrvni. Ear11 suiwssive estimate brcciulcs 1~1re :i~,curate siuce 1101.~ iui~rniati(~~ is av;iilabk 1s

Process Engineering 47 the job approacl~c? co~rililvtio~i. TIIM\ <Iat>i :~Ilvays 11wr11i1c of gre:it r.:1111t. to the cuotra<,tor lor wit duilit,- uf his (1-1 olx,r:itio~~.~. Oftm the "running-owr" lirt.lin~inary r-timitt,~ van IN. tracecl to additions or to improvrnicnts in tliv iwiginal ~lcsigir, Design <Iran-ing* are usually eirculattd tlm~ugll tile 1-ariow ilc~xirt~ncrit~ of tl~c c~tston~t~r'c orgnnizatiun and idrns for ;idditiuns to the plmt oftcli cree1) in iluri~lg this proce*. Tlic customer's project enginerr can hetter control ro-t. therefore, by requesting frequent reestiulates of the find plant cost.

Econon~ie eval~~ation of l~roccs-re ?houl~l rontitn~e even after a plant goes into ioperation. Plans fur inrrea..ing protlurtiun ur fur obtainilly lon.er iroduction rods nmt all he evaluated on a d~ollnr basis. Procesb evalua- tion and its prin~ary tool cost estimation permeate every phase of the derelopn~ent. design, construction, and ojwration of :i plaut. Both operating emi~panic. and constructil~n firni.; tnaiutuin cou~petent estimating departlncnts. 'Tliesr groups arc ili~isions of the cimtral en- gineering orgnniz:ltion nnr! arc u.u:dly daffed nien of con~iilerai~lr experience in estili~ating rvork. lloat frequcntl>- ccncl~ 1;tn sprcializes in our plmr of estimating, mrh n? piping or vessels. The 11rimary 11uty of cstitnating departments is to tic\-?lop ac(,nratc cmstructi~~n cobt cstitnates based on reasonably firm design inforlnation ar~l the latest cquil~rnent costs available. Such estimates arc time con~uming aud c~tly, l)~t are necessary in the dn.clopwnt of quotations by contractors or appropria- tion estinlatrs by operating companies, n-hich are presented to manage- ment prior t11 the alloration of funds fur a project.

(Parte 7 de 10)

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