1999nprasession1qa

7/27/2019 1999NPRASession1QA

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Session I - General Processing

A. Treating and Desalting

Question 1As refiners are processing increasingly heavier, higher salt content crudes, hat retrofits are refinersusing to !aintain or i!prove desalting efficiency" #hat is the typical$%est perfor!ance &percent salt

re!oved' of single-stage desalting of heavy crudes &(1) API'" #hat can %e done to i!prove the desaltingefficiency of a single stage desalter so that it can treat a high salt content crude"Question *Is anyone using unstripped sour ater as ash ater to the desalter" If so, hat is the +uality &p, ,*S, etc.' and$or source &crude, /00, DS, etc.' of the unstripped sour ater and hat pro%le!s aretypically incurred"Question #hat !ethods are %eing e!ployed to reduce %enene fro! individual refinery ater strea!s, such asdesalter effluent %rine, to insure 2SAP co!pliance"Question 3o are refiners currently handling color pro%le!s in their 4et fuel caustic treating unit"

5. 6u%e 7il 8anufacturing

Question 9#hat techni+ues are %eing used to !anage fouling in 82: unit dou%le-pipe procedures" as anyone triedcoating surfaces ith phenolic resins or other coatings" Are varia%le speed drivers %eing installed on thescrapers to allo varying scraping cycles for different stoc;s"Question #hat is the reasona%le e=pectation for the purity of the 8P solvent that has %een used in the e=tractionprocess for a nu!%er of !onths" Do you see conta!ination %y the initial %oilers of the light lu%e oilstrea!s processed" #hat operating li!its are i!posed to prevent$!ini!ie conta!ination %y these lightlu%es" #hat concentration of 8P is e=pected in the raffinate and e=tract strea!s"

0. Solvent Deasphalting

Question )#hat e=perience have refiners had ith *S in the circulating solvent" a' In particular, hat *Scontents have refiners o%served in the solvent hen processing vacuu! toer %otto!s feedstoc;s derivedfro! sour crudes" %' #hat steps have %een ta;en to control the solvent *S content" c' #hat do refinersconsider to %e a reasona%le target for solvent *S content considering %oth safety i!plications andprocess effects"

D. 0rude Distillation

1. 8echanical

Question ?

ave refiners e=perienced fouling of crude preheat e=changers hen processing lo sulfur, a=y crudes!i=ed ith condensates or other non-si!ilar crudes" as anyone identified a fouling !echanis! and a!eans of !itigating this fouling"Question 1@o do spray nole li+uid distri%utors in the upper!ost section of vacuu! distillation toers affectvacuu! syste! perfor!ance"

*. Process

Question 11


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#hat is the e=perience ith tisted-tu%e type, enhanced surface e=changers and the tu%e inserts in crudepreheat service--fouling tendency, decrease or increase in ti!e %eteen cleaning, effect on pressure drop,and perfor!ance i!prove!ents"Question 1*#e currently on-line spall our co;er heaters %eteen heater deco;ing. as anyone done this on their crudeor vacuu! heaters" o successful ere they and hat procedures ere used" Specifically, ere anyspecial precautions used to prevent plugging of %otto!s piping, pu!ps and toers"

Question 1The ash section of vacuu! toers !ay e=perience co;ing or plugging pro%le!s. Are there anytechnologies availa%le for online !onitoring of the location and severity of the co;e deposits$pluggage inthe pac;ed %eds"Question 136i+uid !aldistri%ution caused %y fouling, corrosion or other !echanical da!age of li+uid distri%utors andpac;ed %eds has %een a !a4or concern in the run-life of pac;ed toers. #hat !ethods have %een used to!itigate !aldistri%ution pro%le!s hile online"

2. Instru!entation

Question 19Traditional refinery instru!ents have %een selected to !eet o%4ectives of %eing ine=pensive, highlyrelia%le and providing !easure!ents of sufficient accuracy$control for operation, including start-ups andshut-dons. #ith the use of these instru!ents in Advanced Process 0ontrol &AP0' and on-lineopti!iation, ho are refiners !easuring instru!ent relia%ility" To hat e=tent are techni+ues such asstatistical routines, s!art instru!ents and artificial intelligence %eing used" Are there any otherapproaches to !easuring instru!ent relia%ility"Question 1' and eli!inate 8T52, do refiners anticipate pro%le!s ac+uiring long lead ti!ee+uip!ent or supplies in ti!ely fashion &co!pressors, high pressure vessels, precious !etal catalyst orpiping, etc.'"Question *#hat strategies, %oth short and long ter!, are refiners for!ulating to !eet the proposed ultra-lo sulfur


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specifications for gasoline" If a %an;ing and trading syste! ere esta%lished today, here%y credits could%e earned for sulfur reduction, hat !ethods are li;ely to %e e!ployed"

G. 0o!puter$Process 0ontrol

Question *3#hat integration strategies are refineries developing to integrate real ti!e data syste!s ith plant

%usiness applications &yield accounting$!ass %alance$data reconciliation$planning$scheduling' andrefinery data ith enterprise syste!s li;e SAP"Question *9There are a nu!%er of processes in plants that e=hi%it non-linear %ehavior. 2=a!ples includeC a' gasoline%lending, %' heat e=change netor;s, and c' /00 riser te!perature and feed-rate. #hat is the order of!agnitude of %enefits for e=ploiting non-linear !ethodologies, co!pared to utiliing straight linearcontrol"Question *#hat has %een the success of AP0 and online opti!iation !aintenance progra!s provided %y eitherthird party vendors or corporate engineering staffs" #hat are the refinery staffing re+uire!ents for AP0of co!ple= units &crude, /00 and hydrocrac;er' and inter!ediate co!ple=ity units &refor!ers, al;y,iso!'" /or online opti!iation" #ith refiners at !ini!u! engineering staffing and constant personnelrotations, hat are refiners doing to !aintain continuity of support for AP0 and online opti!iationapplications"Question *)#hat !ethods are %eing used to increase %uy-in and acceptance of AP0 pro4ects %y operations personnelhich help i!prove utiliation and capture of %enefits"Question *?#hat perfor!ance !easures are used %y refiners to evaluate AP0 perfor!ance"

. Safety and Belia%ility

Question @#hat innovative ideas are refineries i!ple!enting in their safety progra!s" #hat perfor!ance !easures

and incentive progra!s do they use" o do you !anage these progra!s to encourage reporting ofincidents and near !isses to push i!prove!ent of the plant syste!s"Question 1PS8 regulations have %een in effect for al!ost 1@ years. #hat are refineries doing to ;eep the PS8process active and hat specific efforts are %eing pushed no li;e A7P revalidation"Question *#hat standards are utilied to insure intrinsic safety of porta%le electronic devices such as !o%ile phones,personal digital assistants and co!puters" Is the use of these devices unifor!ly controlled in refineriesand petroche!ical plants"Question As unit runlengths are e=tended fro! *- years to 9-< years for turnarounds, ho are refiners !anagingthe potential loss of e=perienced people that have unit specific ;noledge of turnarounds$start-up$shutdon procedures to !anage the turnarounds safely"

Question 3#hat are refiners doing to !ini!ie the ris; of fires in pac;ed colu!ns" #hat are sources of ignitionother than pyrophoric iron sulfide" as anyone successfully used a che!ical to neutralie pyrophoric ironsulfide"Question 92fforts have %een !ade to i!prove e!ployee safetyE hoever, an increasing nu!%er of accidents areapparently the result of !echanical failures. o are plants !anaging the need for !echanical safety andrelia%ility against the need to !aintain lo !aintenance inde= values"Question


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#hat a%nor!al situation !anage!ent &AS8' techni+ues are refiners i!ple!enting to i!proverelia%ility"Question >#hat ne develop!ents are refiners i!ple!enting in the areas of alar! !anage!ent, operator graphicdesign and other hu!an interface display i!prove!ents"

I. 8iscellaneous

Question )Given the current e!phasis on reengineering the corporation and !erger driven staff reductions, ho areco!panies leveraging their technical e=pertise" #hat are the perceived advantages$disadvantages of acore engineering pool versus satellite deploy!ent of technical e=perts"Question ?The current trend in the refining industry is to outsource !ore services. #hat types of services arecurrently %eing outsourced in your plant" To hat e=tent ill this trend continue and hat are thera!ifications on plant operation and relia%ility" #hat percentage of your engineering support &design,operations, etc.' do you outsource"Question 3@#hat are refineries doing in the area of :noledge 8anage!ent &:8'" This includes things li;e e%technology, colla%oration tools, search and retrieval and 2lectronic Data 8anage!ent Syste!s &2D8S'"Question 31:inetic !odels are used in various planning, engineering and scheduling groups in refining co!panies.o i!portant is it to have the sa!e !odel used %y each engineering group"Question 3*#hat are refiners doing to plan for the F*: issue that !ay affect their operation" Things li;estaffing$vacation planning, supplies shortages, utility outages, feedstoc; and product shipping disruptions,etc.


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Session I - General Processing

A. Treating and Desalting

Question 1As refiners are processing increasingly heavier, higher salt content crudes, hat retrofits arerefiners using to !aintain or i!prove desalting efficiency" #hat is the typical$%est perfor!ance

&percent salt re!oved' of single-stage desalting of heavy crudes &(1) API'" #hat can %e done toi!prove the desalting efficiency of a single stage desalter so that it can treat a high salt contentcrude"

DABD2C60B is a 4oint venture co!pany that as started %ac; in 1??. The refinery as reva!ped during the!id-1??@s to process 1@@ of 1>HAPI gravity eneuelan crude oil, so this +uestion definitely stri;esclose to ho!e for us.The older crude unit as retrofitted to a lo velocity design on the distri%utors in 1??3, and e run a%out19,@@@ %arrels per day through that particular unit. The to desalters ere changed fro! seriesoperation into parallel operation to give us !ore crude residence ti!e, hich currently runs fro! @ to 3@!inutes. #e upgraded the desalter ater !a;e-up pu!ps to increase the a!ount of ash ater, and echanged the heat e=changer train configuration so that e could co!e into the desalters %eteen *)9 and@@H/. or!ally e stay as close to @@J / as e can.In this configuration the desalters typically re!ove a%out ?> of the salt co!ing in. #e nor!ally see 9 -9@ pounds per thousand %arrels salt content on the inco!ing crude. #ash ater rates are a%out ? to 1@%ased on crude.The ne desalters that ere installed ith the ne crude unit are %ilectric design. That unit as alsodesigned to process 1@@, 1>HAPI gravity eneuelan crude oil, and e have reached a reva!p rate of139,@@@ %arrels a day. These desalters ere designed to operate at @@H/, and e stay pretty close to thatte!perature all of the ti!e.#e did have to retrofit the !ud ash syste! on the ne desalters %ecause e had a lot of solids %uild uppro%le!s. #e increased the noles fro! *3 to >


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desalter, they ill deposit in the %otto! of the vessel. Then they can %e re!oved fro! the vessel ith aperiodic !ud ash.oever, if the !ud ash syste! is inade+uate to handle the increased volu!e of solids associated iththese heavier crudes, deposits ill progressively %uild in the %otto! of the vessel. As the deposits %uild inthe %otto!, the effective volu!e of the vessel ill %e reduced resulting in deterioration of operation.The refiner !ay o%serve increased ater %eteen the grids and increased tendency for the grids to tripout. 7r, he !ay o%serve increased oil in the %rine due to vorte=ing since the volu!e of the desalter ater

leg has %een su%stantially reduced.Also, the %rine re!oval syste! should %e e=a!ined to ensure that no dead legs or uneven flos e=ist.2ither of these conditions can contri%ute to solids %uild up and eventual constriction of the %rine dra. Ifthe %rine dras are constricted, desalter perfor!ance ill deteriorate. The %rine re!oval syste! shouldalso %e sy!!etrical.Begarding the +uestion of salt re!oval efficiency, to i!prove the desalting efficiency of any desalter, one!ust ensure that the fresh ash ater is ade+uately contacting the %rine droplets in the ra crude. A%sentcrystalline salts, one can gauge the degree of contact %y co!paring the salt re!oval efficiency to the aterre!oval efficiency. #hen calculating the ater re!oval efficiency, re!e!%er to include the ater in thera crude as ell as the fresh ash ater. If the fresh ash ater is ade+uately contacting the ra crude%rine droplets, the salt re!oval efficiency ill appro=i!ate the ater re!oval efficiency. If the saltre!oval efficiency is less than the ater re!oval efficiency, additional !i=ing should %e applied to !oreade+uately contact the %rine droplets. Therefore, the salt re!oval efficiency can %e i!proved %y si!plyopti!iing the e=isting e+uip!ent.6oo;ing %eyond the desalting vessel, overall salt re!oval can also %e i!proved %y utiliing the crudestorage tan; as another desalting stage. #e refer to this techni+ue as tan;age dehydration. This progra!consists of addition of a de!ulsifier to the crude as it is %eing transferred fro! ship or pipeline to thestorage tan;. After filling, the tan; is isolated for *3 to 3) hours to allo ater to coalesce. During thisperiod, ater is periodically dran off the storage tan;. At the end of the settling period, the tan; is%rought online and crude is fed to the unit, prefera%ly fro! a floating suction. #e have e!ployed thistechni+ue at !any locations and o%served salt re!oval efficiencies of 9@ to >9.

:BISACGood !orning, and %efore I anser this +uestion, I 4ust anted to say a couple of ords a%out !y%ac;ground.I have a%out ** years ith 0hevron and Gulf, !ost of it in catalytic crac;ing, %ut have or;ed onrefor!ers, al;ylation plants, co;ers and for the last three years or so in hydroprocessing, particularly in

hydrocrac;ing.#e have a couple of crude units here e process less than 1)HAPI gravity crude. 7ne of the! feedsheavy 0alifornia crude and has a single stage desalter. The other feeds a !i= of 8e=ican and eneuelanheavy crude, has a to stage desalter. 5oth ere converted to PetrecoLs 5ilectric technology %efore estarted processing these heavy crudes. 8indful of 8r. DavidsonMs advice on the salt out, let !e 4ust saythe efficiency is a%out ?@ in the first stage of %oth those units.

ST2/AICGood !orning. As a representative fro! 5echtel, !y responses for the !ost part, ill reflect theengineering point of vie. 7ne area here e ill incorporate operating e=perience in our response is indelayed co;ing through our partner 0onoco. 5echtel offers the 0onoco$5echtel delayed co;ingtechnology.As far as this +uestion is concerned, a %ilectric configuration added to a desalter is one ay to processheavier crudes. 5y e!ploying a 5ilectric design in the sa!e sie desalter vessel, a refiner can process up

to tice the crude throughput for a light crude or !aintain the light crude throughput for a heavier crude.6astly, !ethods for increasing desalter efficiency in general are increasing the operating te!perature, useof once through ater and chec;ing the internal distri%ution syste! of the desalter for ade+uacy for thene operating conditions.

2BB2:A8PCGood !orning. /irst, a %it of %ac;ground a%out !yself. 8y or;ing career has %een spent ith 5P andno 5PA!oco. I have alays %een %ased at refineries, firstly the to Australian sites and !ore recentlyas the 8anager of the Process 2ngineering Support Group at our refinery located in Southern /rance. Ihave design and operational e=perience across !ost processes %ut I do favour crac;ing technology.


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Begarding this +uestion, one of the Australian refineries I or;ed at underent a crude unit reva!p a%outthree years ago. #e changed out the *@ year old oe-5a;er grids in the desalter, and installed thePetreco 5ilectric II syste! you see on /igure I-1. There are other ne internal technology such as theoe-5a;er edge that are e+ually applica%le.The reva!p as +uite successful. The desalter capacity has increased 9@ over na!eplate design, andthe salt and ater re!oval efficiencies superior, typically ?>-?), or 1.9 pounds of salt out per thousand%arrels.

The design includes a three grid syste! to !a=i!ie field density plus introduction of the oil and ater ina horiontal plane %eteen the grids, as you can see on /igure I-1. The grids ere also installed so as toincrease ater residence ti!e.As 8r. 2lliott !entioned previously, level control is also very i!portant. #e installed three Agar pro%eshich give +uite accurate ater-oil level control.Another approach to i!prove desalter efficiency ithout replacing the vessel is to provide fle=i%le preheatte!perature control. This %asically entails !odifying crude piping in the preheat train to allo for asing e=changer. That is an e=changer that can %e utilied either %efore or after the desalter, thus!aintaining a !ore constant desalter te!perature ithout sacrificing preheat %y %ypassing e=changes./inally, recently advances in !i=ed valve technology also ena%le i!proved !i=ing, and therefore desalterperfor!ance at lo cost.

5I66SCGood 8orning. I a! fro! the 2+uilon 2nterprises, 660 5a;ersfield Befinery. 7ur plant processes a largea!ount heavy crude. In general all of the !odifications previously !entioned ere !ade at 5B0 to desaltthe heavy crude !ore efficiently. Additionally heavier crudes !ay re+uire higher desalter operatingte!peratures such that the desalter operating te!perature ill !a=i!ie oil$ater separation and!ini!ie ater solu%ility in the oil. In this case you !ay find an e=cellent opportunity to install so!e lolevel crude preheat and get rid of a product fin fan. 7n the other hand, you !ay si!ply find thatrearranging the position of so!e of the crude preheat e=changers ill suffice. eavier crudes ith highersalt contents re+uire !ore ash ater &as a percentage of the charge' than light crudes. There is a goodreference in the 2ncyclopedia of 0he!ical Process and Design, 0hapter 1>, to help deter!ine the +uantityof ater reco!!ended for your particular 0rude properties. If ater disposal or 5enene 2SAPS is apro%le!, %rine recycle !ay %e used to add !ore ash ater hile !aintaining a constant %rine %lodon.Fou !ay also change your desalter internal configuration. I a! sure there are several solutions to %eoffered. 8y personal e=perience is ith changing fro! a 6o elocity up-flo design to the Petreco

5ilectric design. In particular I thin; the point at hich the crude and ater contacts the grids and theirphilosophy for achieving a good even crude$ater !i= is advantageous.In reference to percent salt re!oval efficiency, I thin; that the ter!inology !ay %e !isleading. Thedeter!ination of desalting efficiency !ay also %e affected %y the testing procedure used to deter!ine%efore and after salt contents. Depending on inlet salt content, )@ N ?@ re!oval efficiency is easilyacco!plished. The pri!ary goal is to achieve a desired oullet salt contentE e.g. less than pt%.

#I66IA8 h2I85AKG &oe-5a;er 2ngineers'CThis +uestion is very si!ilar to Question o.199 fro! last yearLs Q O A. In general, the desalter!odifications that are re+uired to process heavy crudes include higher operating te!peratures, largertransfor!ers, increased ash ater rates, and larger vessels. In cases here larger &or ne' vessels are notpractical, reva!ps to current state of the art internals &such as oe-5a;erMs 2DG2' are thealternatives. Another alternative is to dilute the heavy crude ith naphtha, diesel, or lighter crudes toincrease the API gravity and reduce the viscosity. It should %e noted that the typical insolu%le ater

content &5SO#' in the desalted crude for heavy crude applications ill nor!ally increase to the @.9range. Thus, the percentage of salt re!oval ill %e dependent upon the a!ount of ash ater utilied.A single stage desalter ill typically re!ove ?@-?9 of the salt in the crude oil. The percentage !ay %eso!ehat less than ?@ for heavy crudes if the a!ount of ash ater availa%le is lo. The salt re!ovalpercentage ill approach, %ut cannot %e greater than, the percentage of ater re!oval in the desaltervessel. Increasing transfor!er sie and$or ash ater rates &to increase ater re!oval percentage' andincreasing de!ulsifying che!ical rates &to decrease outlet 5SO# content' are the only practical !eans ofi!proving single stage desalting efficiency ithout replacing the internal electrodes.In the past, so!e desalter suppliers have voiced clai!s of achieving to-stage desalting efficiency in asingle stage vessel. oever, none of these technologies have proven to %e successful, especially for


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desalting heavy crudes.

G. S. DAG &Indian Institute of Petroleu!'CTo !aintain or i!prove efficiency of e=isting desalting vessels processing increasingly heavier, highersalt content crudes the folloing retrofits as are suggestedC0hange of desalter type e.g. fro! 6o velocity$ 0yletric to 5ilectric Type. Addition of another stage&single stage to to stage unit'.

Typical $ %est perfor!ance & salt re!oved' of a single stage desalting of heavy crude &(1) API' ould%e around )9.2fficiency of single stage desalter can %e i!proved throughC0ontrol of operating para!eters i.e. deter!ining opti!u! conditions, say .r.t. Te!perature DP across!i=ing valve #ash ater +uality O ratio Dosage of de!ulsifying che!ical 0orrect location of point ofin4ection of oil-ater e!ulsion into desalter vessel. 8odifying desalters vessel electrodes to 5ilectric type.

RA82S #2IT &/luor Daniel'C#ith heavy crudes that have specific gravities close to ater and ith solids, hich I heard !entioned, itis easy to for! a sta%le e!ulsion that is very difficult to %rea; if you run ith the !i=ing valve delta P toohigh. #hat I have found to %e useful is not to run ith the !a=i!u! delta P possi%le, %ut to run ith 4ustenough to get the 4o% done. That ay you do not !a;e such a tight e!ulsion that cannot %e easily %ro;en.Another thing I have learned to do is to raise the te!perature up to the poer li!itation of the grids. Thatloers the viscosity of the oil so you can run ith a loer delta P on the !i=ing valve and get the sa!ea!ount of etting. Also a naphtha recycle has %een helpful, even though that does use energy. Thisloers the viscosity of the oil and the specific gravity, hich again reduces the a!ount of delta P re+uiredand helps separate the ater fro! the oil.

#I66IA8 2I85AKG &oe-5a;er 2ngineers'CBefiners should e=ercise caution if higher operating te!peratures and$or diluents are used to desalt heavycrudes. Although the viscosity of the crude feedstoc; ill certainly decrease if these steps are ta;en, please%e advised that desalter poer consu!ption ill increase. This is %ecause higher operating te!peraturesand diluents increase the crude conductivity. If the increase in poer consu!ption is significant, largertransactors ill %e re+uired.As !entioned %y 8r. 2lliott, salt re!oval efficiency can %e i!proved %y increasing oil-ater contact. 7neay to ensure that the fresh ash ater ade+uately contacts the ra crude is to install a static !i=erdonstrea! of the !i=ing valve. The purpose of the static !i=er is to provide additional contact ti!e ith

!ini!u! shear. As referenced %y 8r. #eith, it is possi%le to create trou%leso!e e!ulsions %y ta;ing too!uch pressure drop across the !i=ing valve.In regards to 8r. DardenMs co!!ents, it should %e noted that the single-stage desalters that are providing?> salt re!oval &on a 1>J API crude slate' contain oe-5a;er internals.

Question *Is anyone using unstripped sour ater as ash ater to the desalter" If so, hat is the +uality &p,, *S, etc.' and$or source &crude, /00, DS, etc.' of the unstripped sour ater and hatpro%le!s are typically incurred"

PB77PSCGood !orning. I ould li;e to first give you the generic anser fro! 5a;er Petrolite. Kse of unstrippedsour ater as addressed to so!e e=tent in last yearLs QOA in Question 19? and also in 1??@, Question1. General guidelines for ash ater +uality include ( 9@ pp! a!!onia, ( 1@ pounds per thousand

%arrels solids, ( 1>9 pp! hardness &as 0aS73' and p %eteen < and ). As ith !any guidelines, thereare e=ceptions to this.7neof the pri!ary concerns in using unstripped sour ater is p. #hen p is a%ove ) there is apossi%ility of for!ing naphthenic acid soaps in the desalter. These naphthenic acid soaps can sta%iliee!ulsions, resulting in undercarry and li!iting the desalterLs a%ility to dehydrate the crude. /or thisreason, so!e refiners add acid to control the p %elo ).Befiners are a%le to use unstripped sour ater ith p %eteen ? and 1@ hen the ionic strength is lo.Such un%uffered ater does not %ringing !uch al;alinity to the desalter, so the resulting desalter effluentis in the


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and vacuu! overhead syste!s. The re!ainder is stripped sour ater. The vacuu! overhead aterconsistently %rings * to > hydrocar%on into the desalter !a;eup dru!, hich gives the ater a cloudyhite appearance %ut does not affect the desalters.8ost p upsets in these desalters are caused %y sour ater stripper perfor!ance, although e have hadp upsets hen the operators have added e=cessive a!ounts of a!!onia to the crude toers. Thea!!onia concentrations the!selves have not %een an issue.

5I66SCI concur ith 8r. Proops regarding ash ater +ualities. The source ater p should %e of particularconcern hen deter!ining hich aters you ill use for ater ash. #hen the p is a%ove ) there is apossi%ility of for!ing soap ith naphthenic acids in the crude oil. 7f course these soaps can sta%iliee!ulsions, reducing the desalters a%ility to dehydrate the crude and increasing the possi%ility of oil under-carry. 0ontrolling the ash ater p as also suggested to our plant as a !eans of dealing ith offspecification ash ater. The p control involved adding acid to the desalter ash ater, there%yreducing the ash ater p %elo the ).@ target. Sulfuric as as suggested, hoever I hesitate to freelyreco!!end the use of sulfuric acid due to the severely corrosive regi!es that !ay occur during thesolution of sulfuric acid and ater.

266I7TTCI found this +uestion to interesting, so I decided to survey so!e of the crude units that e treat in orthA!erica to deter!ine the prevalence of this practice. I found that +uite a fe refineries in orth A!ericaactually use unstripped sour ater as part if not all of the fresh ash ater to the desalter. A fe of therefineries also use /00 and DS unit ater. oever, the vast !a4ority use crude unit, at!ospheric andvacuu! condensate as part of the fresh ash ater to the desalter.7f the 9* respondents to the survey,


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ater is not enough for the desalter, then e introduce ra ater and$or stripped sour ater. In one of ourcrude units, e use the unstripped sour ater as a ash ater to the desalter. So far e have not anypro%le!. The unstripped ater is a%out 9@ of the total and the other is the stripped ater.The +uality of A-toer overhead p is a%out


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7ften refiners reduce the ash ater in order to reduce the %rine rate and there%y reduce the total gra!sof %enene leaving the desalter. oever, further studies should %e conducted to ascertain the effect ofash ater reduction on %enene concentration in desalter %rine. Also, loer ash ater rates !ust %e%alanced ith the pri!ary desalting o%4ectives of re!oving salt and solids.Increasing pri!ary de!ulsifier concentration su%stantially reduced the concentration of %enene indesalter %rine. oever, the study shoed that a si!ilar reduction could %e o%tained %y addition of areverse de!ulsifier at a !uch s!aller dosage. Addition of the reverse de!ulsifier at a concentration of *3

pp! in the fresh ash ater produced a 39 decrease in the %enene concentration in the desalter %rine.So %asically this study proved to points. 7ne as that a real ti!e test !ethod could %e e!ployed todeter!ine the %enene concentration in desalter %rine and opti!iing the desalter operating para!eterscan have a dra!atic effect on the %enene concentration in desalter %rine.

RA075C7ne client sends the %rine desalter ater to a %enene stripper here it consistently re!oves the %eneneto less than 1@ pp% in the stripper %otto!s. The %enene rich overheads are condensed and sent to a sourater tan; and then to a sour ater stripper. The vapors are ta;en overhead to the SBK here the *S isconverted to S7* and %enene vapors are co!%usted at te!peratures greater than *@@@J /.

:BISACI have a couple of different e=a!ples here, not too dissi!ilar to hat you 4ust heard. In the first case, thehot effluent ater fro! the desalter is depressured, flashed to strip out !ost of the %enene, and the vaporis then routed to the vent gas syste!. The ater is cooled and ulti!ately passed through activated car%on.In another case, they gas strip the ater fro! API separator and then pass the vapor through a car%on %ed.

ST22 0KPPS &Syneti='Syneti= has developed and co!!ercialied a ne technology, the Accent Process. The Accent Process is%ased upon active o=ygen transfer catalysis. Accent can acco!!odate a ide range of process conditions,for either continuous or %atch processing. Accent is a process for the re!oval of trace organic co!pounds,hich include %enene, fro! a+ueous syste!s.The process engineering for Accent applications, fro! design through construction, can %e arrangedthrough Pioneer 0o!panies, Inc.

5I66 #ITIG &5etDear%orn'C#e have four applications started in recent !onths utiliing a ne technology applied to the desalter

ash ater hich reduces the %enene content of the desalter effluent ater. This technology does notfunction li;e a nor!al reverse %rea;er to floculate or coagulate the entrained oil in the ater. Theche!istry co!ple=es ith the %enene and drive it to the oil phase. Beductions in %enene content of thedesalter effluent ater of @-9@ have %een achieved.

Question 3o are refiners currently handling color pro%le!s in their 4et fuel caustic treating unit"

PAB:C#e operate three 4et fuel and ;erosene treating units e+uipped ith a charcoal %ed reactor. /irst of all,good caustic preash operation is very i!portant. Beplace caustic in ti!e and do not carry over napthenicacid to the reactor. If you do not have tri-coc; at caustic preash colu!n, then I reco!!end installingthe! to get sodiu! napthenate out to interface of hydrocar%on and caustic. Also, ade+uate air rate andgood te!perature control are critical. :eep air rate less than *@@ %ased on the content of !ercaptans

and the te!perature around 1@@H/. Too a high te!perature ill cause color degradation.

DAIDS7CAcid ashing of the 4et fuel using PetrecoLs !eter cell precipitator has also proven to %e effective fori!proving color of 4et prior to caustic treating. Knfortunately, this is typically only practical if you arerunning a sulfuric acid al;ylate unit so you can use spent acid.

266I7TTCIn addition to the caustic ashing that has already %een !entioned, phenolic antio=idants can also %eadded to 4et fuel to help !ini!ie color degradation. ot all phenolic antio=idants, though, are effective


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in 4et fuel. So!e can actually participate in the color degradation process and further dar;en the 4et. /orthis reason, antio=idant treat!ent !ust %e carried out ith this understanding in !ind to ensure that thedesired color control is provided.Also antio=idants !ust %e added i!!ediately upon final production of the 4et fuel. This early treat!entill ena%le the antio=idant to inhi%it o=idative attac; and !a=i!ie the effectiveness of the antio=idant.

PATBI0IA /7B2B7 &8eriche! 0o!pany'C

0olor pro%le!s in the 4et fuel treating syste! can %e so!ehat dependent on type of crudes. 7therstrea!s such as co;e or gas oil are recycled to the crude unit can cause color insta%ility due to the crac;ednature of the feedstoc;s. #e also found that hen the %asic nitrogen of the untreated 4et is greater than 1pp! the color pro%le!s can occur. Several !ethods can %e i!ple!ented, hich include the acid ashand hydrotreating in order to re!ove the color precursors.8eriche! reco!!ends that in order to !ini!ie color degradation to our treat!ent units, no !ore than1.*9 theories of air should %e added. Additionally the feed te!perature should %e controlled %eteen ?@to11@H/. /inally, suita%le clay filtration ill serve as a final step for ad4usting color.

5. 6u%e 7il 8anufacturing

Question 5#hat techni+ues are %eing used to !anage fouling in 627 unit dou%le-pipe procedures" asanyone tried coating surfaces ith phenolic resins or other coatings" Are varia%le speed drivers%eing installed on the scrapers to allo varying scraping cycles for different stoc8s"

ST2/AIC5echtel is the oner and licenses the Te=aco lu%e oil technologies. #e advise our clients to use specificoperating strategies, such as, setting appropriate operating conditions, the application of dilution solvent,etc, to !ini!ie plugging and fouling pro%le!s.#e ;no of no individual refinery or e+uip!ent vendor, either foreign or do!estic, e!ploying 5echtelMs&Te=aco' lu%e technology ho uses coating techni+ues to prevent plugging or fouling of dou%le-pipee+uip!ent.6astly, e also do not ;no of any refiner ho uses varia%le speed drivers for scrapers. oever, so!erefiners do use inter!ittent operations of the scrapers, particularly hen running heavier stoc;s.

RA075C

I a! fa!iliar ith to refiners that have scrapped surface e=changers. 7ne has phenolic coating on theinternal co!ponents of the e=changers and the other does not. The one refiner that has the internalcoating runs continually ithout a need to hot ash the e=changer %ecause of pressure drop or heattransfer reasons. 7n the other hand, the other facility has to %ypass or shut don the cooling !ediu! toallo the ar! charge solvent !i=ture to flo through the scraped surface e=changers there%y !eltingthe solidified !aterial and elevating the pressure drop.The %enefit of the coating is !ore pronounced the s!aller inner pipe and less pronounced on the largerinner pipes. The s!aller %eing


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of an SDK are usually having varia%le speed arrange!ent through gear%o= !echanis! %ut the refinersrarely ta;e advantage of this provision and generally run the! on a fi=ed speed. The %asic function ofscrapers is to provide agitation for !aintaining slurry ho!ogeneity and re!oval of a=y layer fro! innerall surface to allo for heat transfer. The shear conditions also i!pact the crystalliation ;inetics ithhigh shear conditions even causing attrition of crystals. Generally, lo shear conditions favor grothhile, !oderate conditions tend to pro!ote nucleation. Rudicious choice of scraper speed$shearconditions, depending upon the feedstoc; and the actual processing sche!e, !ay lead to process

advantages at the cost of so!e-hat higher !aintenance re+uire!ents.

226I7 BKI5A6 &2==on Besearch O 2ngineering 0o!pany'C#e have significant e=perience ith this pro%le! of plugging in scrapped surface e=changers, and eused to deal ith that *9 or @ years ago. Since then e have not had any !ore pro%le!s %ecause ereplaced the scrapped surface e=changers ith a proprietary deal chill crystallier. Deal chill is aproprietary 2==on technology for ;etone a=ing.Begarding the coating of internals, yes, it is effective to coat the internals of scrapped surface e+uip!entith so!e phenolic coating 4ust li;e 8r. Raco% !entioned. In the case of the deal chill crystallier, one ofthe previous responses said that high shear environ!ent is detri!ental to crystalliation or !ay %edetri!ental to crystalliation. In our technology, e have found the contrary of that. A highly shearenviron!ent is actually conducive to the for!ation of very unifor! and spherical crystals, and that thea= and oil are !uch %etter than hen you use 4ust scrapped surface e+uip!ent.0oncerning the plugging of internals and the effectiveness of scraping of the internal tu%e, hat e havefound is that there are to different types of !echanis!s to push the scrapers in the scraped surfacee+uip!ent. 7ne type uses lift springs and the other one uses coil springs and a plunger, and the latter has%een found to %e !ore effective in general./inally, concerning the fre+uency of plugging and hether or not you plug, e have found that the +ualityof the a= slurry hen you crystallie a= out of the a=y feed, the +uality of that slurry has a lot to doith ho fre+uently you plug up. #hat e have found is that ith the deal chill slurries and the sphericala= crystals, e have very fe plugging pro%le!s any!ore e=cept in very s!all dia!eter scraped surfacee+uip!ent. 5ut on anything li;e


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%earing. The opti!u! level and dilution sche!e can %e esta%lished through si!ulated run, on la%$%enchscale units or controlled plant trials e!ploying varied S$/ ratios$dilution sche!es. 0o!ple= !athe!aticaltreat!ent suggested usually needs e=peri!ental$plant verification.

226I7 BKI5A6 &2==on Besearch O 2ngineering 0o!pany'CSo!e lu%e refiners !ista;e the need for a high solvent to feed ratio ith poor crystalliation. They do notrecognie that the pro%le! is poor crystalliation and they try to co!pensate for it %y increasing the

solvent to feed ratio e=cessively. As a result, hat they are trying to do is !aintain the a= to oil yield inspite of poor crystalliation, 4ust %y %rute force increasing the a!ount of solvent that is circulated in theplant. This in turn achieves the yield %ut reduces the effective filtration capacity of the unit.#hat e have found in converting conventional dea=ing units ith spread surface e+uip!ent to the dealchill technology is that e can reduce the solvent to feed ratio as !uch as @ to 9@, and e haveconverted a%out 1@ or 1* units. At the ti!e e have reduced the solvent to feed ratio, then the effectivefiltration capacity has increased %y a%out 9@, and e have !aintained the sa!e yields or have i!provedon the %ase case yields.To piggy%ac; on hat 8r. Raco% said a%out solvent co!position, I thin; opti!iing the solventco!position is ;ey. It is 4ust as i!portant as opti!iing the solvent to feed ratio though no one raised the+uestion a%out that. The pri!ary %enefit of ad4usting the solvent co!position for each particular feedstoc;is to !ini!ie the spread %eteen filtration te!perature and pour point so a plant that is refrigerationli!ited can %enefit i!!ensely fro! opti!iing the solvent co!position. At the sa!e ti!e an opti!alsolvent co!position also !a=i!ies the a= oil yield and filtration capacity.

8I0A26 8IT2B &6yondell-0itgo Befining 0o!pany'C8y e=perience ith solvent dea=ing is ith the DI0I66 process. 6ighter feedstoc;s do allo for aloer solvent to feed ratio. As feedstoc; viscosity increases, a higher solvent to oil ratio is re+uired. 8yreco!!endation ould %e to, for e=a!ple on a 1@@ SKS viscosity feedstoc;, start at a solvent to oil ratioof a%out 1.9 and %egin !onitoring the percent oil in the slac; a=. As the solvent to oil ratio is increased,a decrease in the percent oil in the slac; a= should %e noticed. Solvent to oil ratio vs. percent oil in slac;a= can %e plotted. A %rea; point should %e seen here no !ore %enefit fro! increasing the solvent to oilis noted. Bepeat this process for any other feedstoc;s that you !ight run. Solvent to oil ratio vs. a= freeoil yield can also %e plotted to search for the %rea; point.

Question ;#hat is the reasona%le e:pectation for the purity of the 6P solvent that has %een used in the

e:traction process for a nu!%er of !onths" Do you see conta!ination %y the initial %oilers of thelight lu%e oil strea!s processed" #hat operating li!its are i!posed to prevent$!ini!ieconta!ination %y these light lu%es" #hat concentration of 6P is e:pected in the raffinate ande:tract strea!s"

ST2/AIC6o %oiling point co!ponents ill conta!inate 8P, particularly hen running light stoc;s. The @ neutral ill re+uire special attention during the design phase, hile the 1@@ neutral andheavier stoc;s do not represent as !uch of a pro%le! ith a properly designed unit. This conta!ination isa !a4or concern if only light stoc;s are processed in an 8P e=traction unit. 0onta!ination fro! lo%oilers ill clear up hen heavier stoc;s are processed in the unit. #e loo; at typically @.9 to 1 oil inthe 8P as %eing accepta%le. To prevent solvent conta!ination, e reco!!end that the e=tract heaterte!perature not e=ceed 99@H/.So!eti!es 8P conta!ination is the result of entrain!ent rather than fluid e+uili%riu!. In this case,

conta!inants ill enco!pass the entire feedstoc; %oiling range. As refiners push the li!its of their unit,this pro%le! %eco!es !ore co!!on.The raffinate and e=tract !i= co!positions are a function of operating conditionsC te!perature, 8Pdosage rate, etc.E and feedstoc; properties, such as the feedstoc; source &naphthenic or paraffinic crudes'Eviscosity, +uality, I, etc. If the only infor!ation availa%le as that the feed, as fro! a typical good lu%ecrude at a typical I level, e ould esti!ate the raffinate and e=tract !i= to %e appro=i!ately 19 and)9 8P respectively.

RA075CThe operation I a! fa!iliar ith processed a=ie lu%e stoc; hich produces 1@@ and


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#a= /ree 7il. The purity of the 8P re!ained ??.* P8 after !any !onths of operation.The nor!al 1@ point of the 1@@ SKS oil as around 9o /. In this operation, no light endconta!ination as o%served.To prevent the conta!ination %y the light lu%es, the stripper toer top te!perature is !aintained at or%elo 3@@o/.Knder nor!al operations, test of the e=tract and the raffinate indicated that they contained less than .@8P.

B. S. :AKSI: &Indian Institute of Petroleu!'Cor!ally the purity of 8P is not deteriorated during use in the e=traction process if the para!eters inthe recovery section are controlled properly. oever, recently co;e for!ation in the e=tract one of thee=traction colu!n has %een reported to occur %y several refiners. This has a direct %earing on the purity ofthe solvent, hich is governed %y !aintaining refractive inde= level of the 8P.As for the latter part of the +uestion dealing ith the concentration of 8P, the concentration of 8P inlu%e raffinate and e=tract strea!s is controlled %y continuously !onitoring through G.0. The acceptedconcentration levels are 9 and 1@ pp! in solvent free raffinate and e=tract strea!s respectively.

0. Solvent Deasphalting

Question )#hat e:perience have refiners had ith *S in the circulating solvent" a' In particular, hat *Scontents have refiners o%served in the solvent hen processing vacuu! toer %otto!s feedstoc8sderived fro! sour crudes" %' #hat steps have %een ta8en to control the solvent *S content" c'#hat do refiners consider to %e a reasona%le target for solvent *S content considering %oth safetyi!plications and process effects"

:BISAC#e operate a fairly large SDA plant in our Bich!ond refinery in 0alifornia, hich feeds vacuu! toer%otto!s fro! sour crude. This plant as converted to B7S2 e=traction a fe years ago. Knfortunately, edo not regularly !easure the *S in the circulating solvent, %ut occasionally, e have seen nu!%ers inthe 9@ to >@ pp! range &and higher than that in the vent gas'. /or control e %asically ensure that thevent valve is open so there is enough of a purge fro! the plant.I should also add that *S is 4ust one of theissues. /or us, actually 07* is orse %ecause our resid tan;s are purged ith 07*. #e %elieve that theseaccu!ulated gases can affect the solvency poer of the solvent.

The other issue, of course, hen you are tal;ing a%out *S, is et *S crac;ing. According to ourinspection guidelines, again, the nu!%er ought to %e so!ehere in that 9@->@ pp! range to avoidpro%le!s. I !ight also add that e have o%served !ore odors in the plant henever the %leeds have %eencut %ac;.

STF2SC#e have a fairly s!all SDA plant at Phillips, and it runs on seet crude, so this does not really go to theheart of this +uestion. onetheless, e do !easure *S in our circulating solvent, and e do not haveany. It is not detecta%le. #e really do not ta;e any special care in re!oving it e=cept the nor!al stripingin the fractionator. #e do not see any significant corrosion.

G. S. DAG &Indian Institute of Petroleu!'C*S in circulating solvent in deasphalting operation is unli;ely to affect solvent +ualities %ut it can %e acause of corrosion of e+uip!ent. oever regarding *S content in circulating solvent, its li!its etc. can

%e %est ansered %y refiners operating deasphalting units ith high sulphur feedstoc;s.

BAF87D /67FD &:ellogg, 5ron O Boot'C*S found in the solvent of deasphalting units enters the syste! dissolved in the vacuu! residue or iththe !a;eup solvent. The operating conditions ithin the SDA are not severe enough to crac; the sulfurfro! the residue. The a!ount of *S dissolved in the residue feedstoc; depends on the perfor!ance of thevacuu! toer. 7ne of our B7S2 licensees reports that they see the *S concentration in their solventvarying ith the perfor!ance of their crude vacuu! toer. Therefore, it is very difficult to predict the*S concentration in your solvent.


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The solvent recovery section of the unit can %e designed to control the *S level ithin the unit. Thesolvent dru! can %e designed ith provisions for purging the vessel to control the *S at an accepta%lelevel. The client defined accepta%le level is an econo!ic consideration %ased on solvent losses versus the*S level desired. If e=cessive solvent vapor venting is encountered, a slipstrea! of the solvent could %econtacted ith a caustic or a!ine. The solvent !a;eup syste! !ay also %e treated if needed.

In addition to considerations of safety and !aterials of construction, high concentrations of *S in the

solvent can affect the operation of the unit %y re+uiring a%nor!al operating conditions to !eet the desiredunit perfor!ance. *S in the solvent loop acts as a very light solvent. The lighter solvent co!positionre+uires loer e=traction vessel and recovery section te!peratures, higher operating pressures, andproduces a loer DA7 yields.

D. 0rude Distillation

1. 6echanical

Question on a si= !onth cycle. This !eant thate=changers operating in the te!perature regions of asphaltene deposition ere cleaned perhaps every

three !onths to !aintain ade+uate preheat to the furnace. 7ther e=changers ere not cleaned for up tofour years essentially during unit turnarounds.

DAIDS7C6o sulfur a=y crudes are pri!arily paraffinic in natures. onsi!ilar crudes such as condensates orasphaltic type crudes are !ore aro!atic in nature. The asphaltenes in these crudes are sta%ilied in a!icelle %y resins and aro!atics. There is an e+uili%riu! %eteen the oil !ediu! and the outer part, i.e.,sta%iliing portion, of the asphaltene !icelle. #hen there is a large sing in the paraffin to aro!atic ratioin the !ediu!, it can upset the sta%ility of the asphaltene !icelle, especially hen another desta%iliationforce is present, as is te!perature, in the hot preheat train.8itigation of this fouling !echanis! can %e addressed through appropriate %lending and the use ofadditives.

266I7TTC

#e have had recent e=perience ith a refiner that is processing lo sulfur a=y crude and an asphaltic,!iddle eastern crude. This refiner did not e=pect to have any pro%le!s, since he as processing thesecrudes in %loc; operation. oever, the refiner %egan to e=perience severe fouling of the to at!osphericresid versus crude e=changers. /ouling developed on the resid side of the hottest e=changer and thenprogressed to the cooler e=changer. The e=changers needed to %e cleaned ithin ?@ days of start of run.As 8r. erren;a!p !entioned, e suspected asphaltene deposition as the !echanis!. #e did in factcollect sa!ples of the crude, too; the! to the la%oratory and perfor!ed an asphaltene sta%ility test. Theindividual crudes ere tested and %oth ere found to e=hi%it a !oderate tendency for asphaltenes toprecipitate ith the addition of a nonpolar solvent. oever, hen the crudes ere %lended asphaltenesprecipitated !uch !ore readily. Therefore, e concluded that asphaltene precipitation as the pri!ary


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!echanis! of fouling and proposed application of an asphaltene dispersant.Initially a !oderate dosage of asphaltene dispersant as applied during %oth crude runs. Besults ereencouraging, so the dispersant dosage as opti!ied. The refiner o%served opti!u! perfor!ance ith alo dosage on the asphaltic run, !oderate dosage during the a=y run and a high dosage duringchangeover and slop processing.The che!ical provides %enefit during the a=y run %y dispersing inorganic ele!ents in the crude andpreventing agglo!eration ith high !olecular eight paraffins. After application of this progra!, the

e=changers ran for 11 !onths ithout cleaning.

PAB:C#e handle !ore than 9@ ;inds of crudeE therefore, e have also sa!e e=perience hen processing losulfur crude ith a condensate. 5ased on our e=perience, after and during crude %lending, the solvencyeffect of condensate can cause a loss insta%ility of crude tan; %otto! sludge, hich contains inorganicsalts, asphaltene and !ud, etc. The sludge dissolved in the crude !i= and crude carried the sludge into thecrude unit and then eventually the sludge can %e precipitating the desalter and the crude preheate=changer circuit.The other hand, in our plant, the yield variation of high sulfur crude !i= is relatively s!all in order tosupply the feed stoc; to the upgrading facilities li;e B/00 plant, %ut that of lo sulfur crude !i= is veryhigh. Therefore, the fouling tendency of lo sulfur crude is !ore severe than that of high sulfur crude.

STF2SC#e also had si!ilar e=perience to 8r. erren;a!pMs, %ut not in the *@@H/ region. The pro%le! e hadas in a seet crude unit here e e=perienced fouling hen e got a%ove 9@H/ in the desalted crudeside of the heat e=changer. /or us, the non-si!ilar crude as /orcados and as usually in a %lend ith5rent, Quai I%oe, and 0usiana. #e in4ected a dispersant che!ical and got rid of the pro%le!.

S. P. :ADAB2 &5harat Petroleu! 0orporation 6i!ited'C#e have a refinery in 5o!%ay here e are processing nonsi!ilar crudes. The crude as then changed tolo sulfur, high a=y crude of paraffinic nature. The percentage of the seet crude as increasedgradually. There as no e=perience of fouling. oever, hen the percentage as increased to !ore thana%out @, e o%served that the heat e=changers, heavy %oilers in pri!ary crude and vacuu!residue started shoing serious fouling. The pro%le! as affecting the production. A study has %een doneto deter!ine the principal reason. #e started trac;ing %ac; fro! the crude into the at!ospheric %otto!collecting various sa!ples. #e sought help fro! the national la%oratories in India and carried out studies

fro! the ra crude, the crude fro! desalting, crude during transportation ith additives, crude in storageand at!ospheric residue during the process. #e learned that henever there as e=changers having aparticular type of tu%e oil te!perature, the higher !olecular additives, hich ere there ere depositingout in the e=changers leading to the pro%le!. The solution as to go to the %loc; operation of processingseet crude folloed %y the sour crude. #ith the help of various additive !anufacturers and the nationalla%oratory e developed a che!ical to re!edy this pro%le!. Presently this pro%le! is not %eing faced. In anutshell, the additives, hich ere %eing used to reduce the pour point of the a=y crude asprecipitating out at a certain tu%e.

DABI BI02 &AB07 Products'C/or the panel !e!%ers that ansered, are there any o%served threshold, as far as the !i=ture of losulfur, a=y crudes ith condensates or other non-si!ilar crudes, that hen crossed ould initiate thepheno!enon of asphaltene precipitation"

STF2SCI do not ;no.

DABI BI02 &AB07 Products'CI a! curious a%out the order of !agnitude &1@$?@ !i=, 9@$9@ !i=, @$>@ !i="' for the ratio of seet losulfur a=y crude to condensate crude that !ay initiate asphaltene precipitation. #hen %lending differentcrudes, ill the degree of asphaltene precipitation change depending on the order that the crude are%lended"

STF2SC


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/orcados as the a=y crude and runs a%out >@ of the !i= hen e have precipitation pro%le!s. AarningC e ould not consider percent a=y crude to %e sufficient alone to predict fouling potential.

Question 1=o do spray nole li+uid distri%utors in the upper!ost section of vacuu! distillation toers affectvacuu! syste! perfor!ance"

ST2/AICPu!paround return spray noles function to condense light vacuu! gas oil in vacuu! toers. This alsoserves to !ini!ie the load of condensa%le hydrocar%ons to the vacuu! syste! there%y !aintaining thedesired lo pressure operation in the toer. 7verloading the vacuu! syste! ith condensa%lehydrocar%ons results in increased toer pressure and hydrocar%on product loss to the e4ector slop oil.This is especially critical for dry vacuu! toers here the nor!al flo to the e4ectors ill %e %ased onlyon air lea;age into the syste! and an alloance for crac;ed gases. The overhead strea! to the vacuu!syste! is relatively s!all and !ay not ta;e into consideration any light vacuu! gas oil carryover hichill adversely i!pact the capacity of e4ector syste!. ydrocar%on carryover ill e=acer%ate the situation ifthe alloance for lea;age and crac;ing as not ade+uately covered in the original design. This is oftenthe case hen heavier crudes are processed re+uiring higher flash one te!peratures./or situations here !oderately high li+uid flo rates, typically greater than * gp! per s+uare foot oftoer cross section, or here high spray nole pressure drops are e!ployed, unaccepta%le li+uid dropletentrain!ent into the vacuu! toer overhead vapor strea! !ay result. This situation typically occurshen a heavy diesel product is condensed in the top of the vacuu! toer.6ong ter! operation of the vacuu! syste! here li+uid entrain!ent is present could da!age the e4ectornole, hich in turn ould i!pact the efficiency of the e4ector syste!.

2BB2:A8PCBegardless of hether a spray syste! is used or not, e have not really seen any significant effect on thevacuu! syste! perfor!ance ith a correctly designed syste!. 8r. StefaniMs points are all valid. Thevacuu! loading is !ainly affected %y the light ends in the feeds, the crac;ed gas related to the heatedte!perature and the vacuu! unit overhead te!perature.7ne interesting pheno!ena for vacuu! syste!s incorporating a pre-condenser that e have seen isinstances here the vacuu! perfor!ance is i!proved as the slop oil yield increases. It appears to act as asponge at the outlet of the pre-condenser.

5I66SCGenerally using a spray nole li+uid distri%utor should not negatively effect the vacuu! syste!perfor!ance. oever, if the spray noles are plugged or running a%ove design capacity, they !ay createan aerosol of light li+uid hich can carry over to the vacuu! overhead syste! and overload thecondenser. A de!ister pad !ay %e installed to reduce li+uid carryover, hoever they !ay also %eco!eplugged and cause pressure drop pro%le!s. So!e process specialists reco!!end a trough drip syste! asthe prefera%le top section distri%utor. These syste!s or; ell, hoever they can %e difficult to reinstallduring 8aintenance turnarounds.I prefer spray syste!.

PB77PSCI agree ith the previous panelistsL co!!ents. #e have vacuu! toers at Pine 5end that do not haveprecondensers and e have seen e4ector diffuser throat erosion that e %elieve is caused %y 6G7entrain!ent. 7ne solution to these pro%le!s is larger spray noles to reduce pressure drop. #e also

suggest !ist eli!inators in the top of the toer, or sitching fro! a spray nole to a trough typedistri%utor.

Scott Golden &Process 0onsulting Services, Inc.'CSpray nole distri%utors on the top pu!paround of vacuu! colu!ns ill not adversely affect the e4ectorsyste! perfor!ance on !ost vacuu! units. 0olu!n operating pressure !ay %e i!pacted hen thedistri%utor operates ith high pressure drop, the e4ectors are sied incorrectly, or hen processing a=ycrude oils. #hen the distri%utor operating pressure drop is a%ove 19-*@ psi s!all droplet sies are for!edand high entrain!ent can result. igh entrain!ent increases first stage e4ector load and !ay increaseoperating pressure. Generally the incre!ental e4ector load is s!all and can %e handled ithout noticea%le


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pressure changes. 7ccasionally the inter-condenser tu%es ill %e coated ith a=. This results in lo heatre!oval, hich can raise first stage e4ector discharge pressure a%ove the !a=i!u! discharge pressure&8DP'. This ill dra!atically increase colu!n operating pressure %ecause it causes the e4ector to %rea;.

RA S2DS2 &Shell Glo%al Solutions K.S.'C7ur standard syste! in Shell is alays to apply spray syste!s in acuu! 0olu!ns in feed prep service.#e have a standard rule to apply a nu!%er of noles guaranteeing a%out *@@ spray coverage. or!ally

e select ?@ spray angle, not 1*@, %ecause that gives least entrain!ent. /urther!ore e ensure the nolepressure drop is such that ato!iation is avoided. noles. #e have an in-house design progra!, hichopti!ies the layout for our designer.


20/62

*.Process

Question 11#hat is the e:perience ith tisted-tu%e type, enhanced surface e:changers and the tu%e inserts incrude preheat service--fouling tendency, decrease or increase in ti!e %eteen cleaning, effect onpressure drop, and perfor!ance i!prove!ents"

PB77PSC7ur Pine 5end refinery installed to 5ron tisted tu%e heat e=changer %undles in heavy vacuu! gas oil&G7' vs. crude service in April 1??). /ive !ore %undles ere installed last !onth in crude vs. G7pu!paround and crude vs. o. 1 fuel oil pu!paround service. In all applications, the %undles are typeA2T e=changers ith crude oil on the tu%e side, and ere all %undle replace!ents into e=isting shells.6ong ter! perfor!ance of the %undles has yet to %e deter!ined. The to %undles installed in 1??) haveshon no significant loss in heat transfer perfor!ance. In this service e sa an ) fold increase in heattransfer coefficient &/igure I-'. That is pro%a%ly a%out as good as you are going to get %ecause the old%undles ere o%viously +uite lo - around a 19 overall coefficient - operating ith lo Beynolds nu!%eron %oth sides.The !ost significant pressure drop reduction as on the shell side of the e=changer, hich is thepu!paround circuit. There as an appro=i!ate *@ reduction in shell side pressure drop, and thisalloed us to increase the pu!paround rate. Ta;ing full advantage of reduced pressure drop !ay re+uirereplace!ent of spray noles, pac;ing, control valves or other co!ponents in the syste!.

266I7TTC#e are fa!iliar ith a refiner in 2urope ho has also o%served a significant increase in the heat transferrate %y using tisted tu%es in G7 to crude service. /ouling rate, hoever, has %een si!ilar to othere=changers in parallel service that did not convert to such tu%es. 0leaning has not ta;en place %ut ise=pected to %e of si!ilar difficulty to cleaning conventional e=changers. Also cleaning of thesee=changers is e=pected to have the sa!e effect on heat transfer as cleaning conventional e=changers.Tu%e inserts have also shon increases in heat transfer rates, %ut they have so!e dra%ac;s. Inserts haveto %e replaced appro=i!ately every to years. This re+uires the heat e=changers to %e ta;en co!pletelyoffline. Also, hen processing naphthenic crudes, corrosion of the inserts have %een o%served, eventually%rea;ing the insert and %loc;ing the individual tu%es. Should o%struction occur, the refiner !ust ta;e thee=changer out of service to re!ove the insert.The co!%ination of inserts ith a fouling control che!ical progra! has also %een e!ployed at several

different refineries in 2urope. igher heat transfer rates in co!%ination ith loer fouling rates have%een the result.

:BISAC#e have a little %etter luc; ith tu%e inserts, hich I ill share ith the audience.A fe years ago it as noticed that a couple of e=changers in our crude preheat train in one our crudeunites had relatively lo heat transfer rate and re+uired fre+uent cleaning. Kpon further scrutiny it asdeter!ined that at least a couple of those had relatively lo tu%e velocities, feet a second or so. During ashutdon hen one of the e=changers had to %e retu%ed anyay, it as decided e ould go ahead andtry tu%e inserts called Spirelfs. It is !anufactured %y 2lf in /rance and sold %y a co!pany out of ouston.The installation as fairly +uic;. #e had a co!pany representative fro! ouston there ith us to helpand guide us during installation. 5efore installing those tu%e inserts, this particular e=changer used toneed cleaning a%out every to years and the K-factor ould drop a%out 9@ of here it as hen estarted after cleaning the e=changer. It has %een a%out to and a half years no and the K-factor is

holding very nicely and has not had any pro%le!s.The advertised %enefits ere that it ould increase local velocities and the pressure drop increase ouldonly %e a%out 19 or *@ as opposed to, say, dou%ling the nu!%er of tu%e passes. Indeed, e have onlyseen a !odest increase in pressure drop. The e=changer, as I say, is still online after to and a half years.#e have not +uite run into the situation 8r. 2lliott is tal;ing a%out. opefully e can report %ac; acouple of years fro! no and let you ;no ho ell it is perfor!ing.

ABTKB :BK2G2B &2lf Antar'CI a! or;ing for 2lf Antar /rance ith a syste! called SPIB26/. I anted to respond to the previousco!!entorLs re!ar; that the typical service ti!e re+uires a replace!ent every to years.


21/62

I thin; that operators should distinguish %eteen the different types of inserts. There are at least threedifferent types of tu%e insertsC a stationary type, a rotating type, and a vi%rating type. All these devices ai!at fouling reduction and increase in tur%ulence in the tu%eside flo, %ut they have different design featuresand or; in different ays. And, yes, there are so!e inserts, hich have to %e replaced every to years,and there are other inserts that typically stay in service 9 or < years, fro! turnaround to turnaround,ithout the need for in-%eteen replace!ent. So, I ould li;e to reco!!end that operators shoulddistinguish %eteen the different types of devices and their respective service life, and the type of

application that they are intended to %e used for.

Question 1*#e currently on-line spall our co8er heaters %eteen heater deco8ing. as anyone done this ontheir crude or vacuu! heaters" o successful ere they and hat procedures ere used"Specifically, ere any special precautions used to prevent plugging of %otto!s piping, pu!ps andtoers"

ST2/AIC8ost refiners deco;e their at!ospheric and vacuu! heaters during turnarounds. If deco;ing is re+uired!ore often due to e=cessive heater firing to achieve greater capacity or hen processing heavierfeedstoc;s, on-strea! spalling can %e considered. oever, the a%ility to on-line spall a heater re+uiresfour conditions. a!ely, the unit !ust %e capa%le of operating continuously at a%out 9@ capacity hile!a;ing specification productsE a !eans to continuously re!ove the spalled co;e is re+uiredE the heater!ust have at least to cells and %oth radiant and convection sections !ust %e capa%le of reduced firing onone cell hile the second cell is at !a=i!u! firing and the heater !ust have a horiontal, donfloconfiguration.7f all of the re+uire!ents necessary for on-strea! spalling, re!oval of the spalled co;e fro! the unit isthe %iggest challenge. 7ptions are to pipe up a heater cell to the deco;ing syste! during operation or toadd provisions for co;e re!oval to the at!ospheric and vacuu! toers. If on-strea! spalling is to %ee!ployed, our reco!!endation is to add provisions to allo for a safe redirection of the heater effluentfro! the corresponding fractionation toer to the heater deco;ing syste!.

5I66SCI concur ith 8r. Stefani. There are no 2+uilon 2nterprises or 8otiva refineries that perfor! on spalls ofvacuu! heaters.

266I7TTC#e, too, have not o%served on-line spalling of crude or vacuu! heaters, and 8r. Stefani covered all of theconcerns that e have a%out this practice.

Question 1The ash section of vacuu! toers !ay e:perience co8ing or plugging pro%le!s. Are there anytechnologies availa%le for online !onitoring of the location and severity of the co8edeposits$pluggage in the pac8ed %eds"

5I66SCIf there is a need I a! sure there is so!eone ready to capitalie ith a ne fancy gadget, hoever, in thiscase, the %asics ill suffice. A single gage pressure survey ith a digital vacuu! gage and thoroughcircu!ferential s;in te!perature survey ill supply enough infor!ation to deter!ine the general e=tent ofplugging. 5y o%taining the colu!n s;in te!peratures 4ust a%ove the suspect pac;ed section and plotting

the! on a radar graph as shon on /igures I-3 and I-9, you can deter!ine the location of the plugged &orinsufficiently etted' pac;ing.oever, this is reactive or;. It is pro%a%ly far %etter to use the ash one inlet and outlet te!peraturesand the ash flo rate perfor! a heat and !aterial %alance across the pac;ing. Fou !ay have to !a;e anassu!ption &or a rough calculation' regarding the latent heat of the ash oil, %ut the idea is calculate ho!uch ash oil is needed to leave &as a rule of thu!%' appro=i!ately of the ash oil as overflash.5arring plugging pro%le!s in the ash one li+uid distri%utor this rule of thu!% should insure that theash one pac;ing re!ains etted and that no co;e is for!ed.

PAB:C


22/62

#e also e=perienced co;ing pro%le! in the ash section of the vacuu! unit. In order to get !ore gas oilproduction, e increased the vacuu! heater outlet te!perature and decreased the ash oil rate. #e ;nethe co;ing sy!pto! %y !onitoring pressure difference %eteen flash one and top of the ash oil section.2ventually, e had to replace the ashing section pac;ing trays.There are several ays to detect this pro%le! as follos.7n line !onitoring the capacity related P across the colu!n and ashing section. 0hec;ing theradial s;in te!perature of the vacuu! colu!n.

If the difference a!ong the! is a%ove 9U., there ill %e co;ing or plugging inside the toer.8onitoring et specific li+uid loading.If the ratio of slop a= to ashing oil is varied ithout any reason, ashing one !ight have pro%le!s.8onitoring vapor te!perature ashing section.If the te!perature increases !ore than 9U. ithout any reason and the color of G7 is degraded, theashing one is plugged.

PB77PSC#ash sections of vacuu! toers are suscepti%le to co;ing and plugging as a result of ther!al crac;ingand also internal da!age caused %y the high velocities and sudden e=pansion of the oil as it enters thetoer. In e=tre!e situations, e=cessive co;ing ill lead to catastrophic failure of the ash sectioninternals as cyclic pressure sings increase differential pressures %eyond original design conditions.Plugging in the ash one can %e detected and !onitored using ga!!a scan and neutron %ac; scanner!easure!ents.A ga!!a 0AT-Scan &0o!puter Aided To!ography N see /igure I-


23/62

S07TT G76D2 &Process 0onsulting Services, Inc.'CThe incidence of ash section co;ing is increasing. eater outlet and colu!n operating te!peratures areincreasing, at the sa!e ti!e refiners try to increase profita%ility %y reducing the ash rate to increasevacuu! gas oil yield. #ash section pac;ing re+uires so!e !ini!u! ash rate otherise it ill co;e.8ini!u! ash rate is a function of flash one and ash section e+uip!ent design. Therefore, no si!plerule-of-thu!% can %e used. The %iggest pro%le! is deter!ining the re+uired ash rate and then!onitoring the unit to ensure the rate is !aintained.

An unscheduled outage can ta;e @ of the lost yield as recovered. This is descri%ed in!ore detail in a paper titled Trou%le Shooting Industrial Pac;ed 0olu!ns %y Ga!!a Bay To!ography,presented at 02 2=po M??.7nline cleaning or ashing is ineffective in clearing solid de%ris fro! plugged distri%utors. Befiners havesuccessfully re!oved ater-solu%le deposits fro! plugged distri%utors ith an online ater ash. #ehave used this at Pine 5end to !itigate salting pro%le!s in a pac;ed co;er fractionator &see Question 3#hat specific !easure!ent applications, utiliing ear Infrared Analyer &IB' technology have %een

atte!pted for purposes of a' inter!ediate strea! specification$standard verification, %' process control, c'co!ponent$conta!inant analysis" o successful and relia%le are these applications"

2BB2:A8PC

In the refinery I currently or; at e currently use IB on 9) different applications onsite. /igures I-1@and I-11 list the!.

These applications range across the crude, refor!ing, /00 and hydrocrac;ing units as ell as for product%lending. The tests the!selves include distillations, flash, freee, cloud, B7 nu!%ers and %lending


28/62

indices, BP, specific gravities, viscosities, refractive inde= and even concar%on.

#e are currently in the process of applying the techni+ues to predict cetane as ell. #e also use the IB+uite e=tensively to give final product certification. This is called 5A2 in /rance. #e also use it as inputto various D80s and also routinely in closed loop process control.

/or us to set up an IB application, a !ini!u! of @ points, or 9@ in the case of a final product

specification, are re+uired to o%tain a good !odel. /or e=a!ple, the precision of the IB !odel !ust %ethe sa!e as the classical che!ical analysis. #e then install the !odel in the la% and$or online.

/inally, e routinely chec; the difference %eteen the value given %y IB and the classical analysis. Thefre+uency of the co!parison is defined for each product or co!ponent according to their i!portance.8ore often if the infor!ation is for closed loop control or is used for input to the D80 advancecontrollers or constraint pushers. /or e=a!ple, in the 0DK the light gas oil cloud point given %y IB isverified tice a ee;. The typical fre+uency is once a ee; for co!ponent or product %lending and once a!onth for each finished product.

DABD2C

In our la%oratory e currently li!it the IB analysis to the gasoline and diesel strea!s. #e currently!easure cetane nu!%er and cetane inde= on diesel in the la%. 7n gasoline, e loo; at total aro!atics,olefins, T9@, T?@, %enene, o=ygenates, research and !otor octane as ell as road octane. #e also do thatsa!e analysis on the gasoline co!ponents that go into the %lender.

7nline applications right no at the refinery are li!ited to finished gasoline octane. #e have replaced the%lending engines on the %lender itself, and to a lesser degree e are loo;ing at controlling gasoline%lending for olefins and aro!atics ith IB analysis.

:BISAC

#e have tried IB analyers in a nu!%er of applications in our refineries including inter!ediate strea!sand final product %lending, and suffice it to say that today e only use it on refor!ers for octane!easure!ent.

PAB:C

#e have !any e=periences ith IB applications. #e have a successful e=perience for gasoline anddiesel %lending in offsite areas since 1??3 and 1??) respectively. The crude unit application &AP0, 7n-line opti!iation ith IB' is under progress and it ill %e finished ithin this year. IB !easure!entstrea!s and properties are as in /igure I-1*.

After introducing IB, e are replacing the conventional la%oratory results ith IB data gradually.

5ut it can not !easure s!all concentration !aterials &pp! level' li;e !etal, sulfur, additive, etc.

IB data have e=cellent repeata%ility and reproduci%ility, and other advantages are instant results, lo

!aintenance cost and si!ultaneous !easure!ent of !ultiple varia%les. The progress of our currentapplication to crude units are as %eloCAuto!atic control of 0DK unit Direct spec control using IB analyer 0ontinuous spec. control duringcrude sitch 0ut point opti!iation Increasing the diesel and other light oil Tight +uality control.

ST2/AIC


29/62

Rust a%out every application in the refinery has %een addressed %y the other panelist. #e are aare ofother applications of IB such as for crac;ing furnaces, %y !onitoring the naphtha feed properties. TheIB instru!ent provides an analysis once per !inute versus the nor!al once per day %y offline la%oratorygas chro!atography. The %enefits ere esti!ated at V1 !illion a year through i!proved product yieldsthrough the a%ility to change the actual crac;ing conditions on an instantaneous %asis.

A second application is the !easure!ent of caustic and caustic %rine solutions ith the detection of the

hydro=ide ion. This i!portant industrial !easure!ent has in the past %een perfor!ed %y a nu!%er oftechni+ues hich are either unsta%le or suffer fro! interference caused %y the presence of other cations!ost nota%ly sodiu!. 6o spectral resolution and the overlap of a%sorption spectra are overco!e throughthe application of !ultivariant cali%ration !ethods.

STF2SC

#e also use IB for octane and gasoline %lending applications.

I also have a couple of e=a!ples fro! the che!ical and plastics part of our %usiness. #e are a%out to putinto service a field IB to do !elt flo analysis.Also, e use IB in an associated che!ical plant forco!position. This lets us ;no hen e have reached the end of %atch, helps speed up the processingthere %y letting us get the %atch co!pleted earlier.

#e also use IB for final certification of a !ethyl!ercaptan product.

226I7 BKI5A6 &2==on Besearch O 2ngineering 0o!pany'C

7n the instru!entation and online analyer %usiness, in lu%e oil applications a%out four years ago edeveloped an online oil and a= analyer that has %een operating successfully no for four years. Iactually visited that plant a%out three ee;s ago, and they are e=tre!ely pleased. #e have the onlineanalyer no fully coupled, or;ing in closed loop ith the process control co!puter. It provides online!easure!ent of oil and a=, not 4ust one or to !easure!ents a day, %ut e are a%le to continually finetune the unit to !a=i!ie the a= oil yield and !ini!ie the oil content of the a= %y-product.

2BB2:A8PC

This application is your instru!ent, it is an IB"

226I7 BKI5A6 &2==on Besearch O 2ngineering 0o!pany'C

To %e honest ith you, I a! not e=actly fa!iliar ith the co!ponents of the e+uip!ent, %ut e havefound it to %e really ;ey for a plant that not only !a;es lu%e oil %ut also sells a=. This is not the oilingplant. This is 4ust the a=ing plant. So having the online !easure!ent has %een tre!endous for theoperation.

S07TT AD2BS7 &:och Petroleu! Group'C

I onder if so!e of the panelists ho have had success ith IB ould co!!ent on sa!ple conditioningsyste!s, particularly for strea!s that contain ater. #e have had difficulty trying to ;eep the ater for!coalescing out of the et strea!s.

2BB2:A8PC

I a! sorry it is not !y field.

Question 1)At least one vendor supplies an instru!ent ca%inet ith sa!ple processing that allos a la%oratory gradeanalyer to %e used in the field as an online analyer. as anyone tried putting a la%oratory G0 into one ofthese ca%inets" Did the field results then !atch the la%oratory results" #ho too; care of the analyer --!aintenance personnel or la%oratory staff"


30/62

STF2SC

Phillips has over @@ la%oratory G0s !ounted in the field doing online analysis. All %ut one of the!,hoever, is in a traditional analyer %uilding. #e have one of these types of instru!ent ca%inet ith ala%oratory G0 !ounted in it. According to the !aintenance supervisor in that area, it or;s ell %ut isterri%le to or; on the rain.

As far as verifying G0 accuracy, at all of our refineries that is a cooperative effort %eteen the la% and!aintenance. They use to techni+ues, hich I thin; are fairly standard. In so!e cases e have a %ottleof a la%oratory standard right there at the analyer. 7n a ti!ed fre+uency, the analyer runs the standardand chec;s itself to !a;e sure it !atches the standard. In addition, for all of the analyers, e ill catch aperiodic sa!ple and send it to the la% to %e co!pared against the analyer reading at that ti!e. There arealso SP0 tools, that are used to identify a trend toards unrelia%ility in the G0.

The hands-on !aintenance is done %y an analyer technician that reports to the !aintenance tea!. Theycall on la%oratory people to help the! ith particularly stic;y pro%le!s.

GATT2C

Since Grace Davison is a catalyst !anufacturer, !ost of !y responses over the ne=t couple of days aregoing to %e fro! either the perspective of our catalyst plants or fro! infor!ation fro! our refinerycontacts.

As far as this +uestion is concerned, e ;no of one refinery that has tried these types of ca%inets, and ealso have e=perience ith the! at our 6a;e 0harles catalyst plant. In general, the to locations have note=perienced good results. At the catalyst plant, at the ti!e, e opted for lo to !id cost applications ofthese types of ca%inets and found that they ere ineffective at controlling dust and ere not te!peraturecontrolled. At the refinery in +uestion, a !ore e=pensive syste! did control the dust$te!peratureenviron!ent %etter, %ut as still not up to e=pectations as far as instru!ent relia%ility is concerned.

At our catalyst plant, e did have a pro%le! ith deter!ining hose 4urisdiction the e+uip!ent ca!eunder, ith grievances filed %y %oth Instru!entation O 2lectronics &IO2' and la%oratory personnel. Thefinal resolution as that plant IO2 personnel !aintained the syste!s. oever, cali%rations ere only

perfor!ed once per ee; due to the or;load, hich affected the accuracy of the !easure!ents. Theanalytical e+uip!ent is no %ac; in the la%oratory.

:BISAC

#e have one syste! installed and operating in one of our #est 0oast refineries on an 8T52 plant. Theanalyer !echanics !aintain that syste! as ell as %oth the online and the la% G0s. Knfortunately thisinstru!ent is the orst G0 of the *@ or so that they have to deal ith. There are several design flasresulting in fre+uent failures of this G0, and at this point e are not reco!!ending that other 0hevronrefineries install such a G0 in an online environ!ent even if it is in a protected enclosure.

PAB:C

So far e do not have any e=perience yet. To i!prove the perfor!ance of on-line analyers, e do a

co!parison test %eteen la%oratory analyer and on-line analyer a%out the sa!e sa!ple according to theschedule.

If there is %ig gap %eteen to results, e cali%rate the on-line analyer until it !atches the result ofla%oratory analyer.

The analyer !aintenance personnel in our plant ta;e care of the on-line analyers and la%oratory staffsdo the la%oratory analyers.

Question 1?


31/62

as anyone had success in using an online p !eter to control the addition of neutralier in a crude unitoverhead syste!" Are the p analyers sufficiently relia%le for closed loop control"

266I7TTC

#e have successfully i!ple!ented closed loop control of neutralier in4ection at several crude units. Inthe past the industry encountered several pro%le!s ith online p analyers that rendered the!

i!practical for closed loop control. These included electrode fouling, electrical interferences, cu!%erso!e!aintenance re+uire!ents and a lac; of onership. All of these pro%le!s had to %e overco!e in order to!a;e closed loop control a success.

I ill %riefly descri%e our syste!. A representative slipstrea! of ater is ta;en off the accu!ulator androuted through the analyer. A slipstrea! is used to allo isolation of the analyer fro! the processstrea!, facilitating periodic !aintenance.

2lectrode fouling is caused %y hydrocar%on and iron sulfide in the slipstrea!. #e !itigate hydrocar%onfouling %y choosing an appropriate slipstrea! dra location. If this steps proves inade+uate, e installhydrocar%on ater separation e+uip!ent on the slip strea! ahead of the analyer. #e !itigate ironsulfide fouling %y closely controlling the slipstrea! flo rate. A !ini!u! rate is !aintained to preventdeposition. oever, the rate !ust %e ;ept %elo a !a=i!u! value since high flo rates can generate astrea!ing potential, causing erratic reading.

The device is su%4ect to stray currents and induced voltages fro! large e+uip!ent in the vicinity of theinstallation. These sources can have a su%stantial influence on the analyer since it is !easuring a verys!all electrical change. Therefore, it is i!perative that the analyer %e properly shielded and grounded.

The original p analyers ere difficult to service ith electrode changeout ta;ing over an hour. The unite currently use is e+uipped ith tist loc; connections that ena%le easy pro%e cali%ration andreplace!ent. The syste! is co!pletely !odular to facilitate the changeout of co!ponents. 5ecause ofthese i!prove!ents, routine !aintenance and cali%ration are no longer ignored. The trans!itter is!icroprocessor %ased, !a;ing cali%ration easy and relia%le.

/inally, one person should assu!e onership of the e+uip!ent. If the che!ical supplier is +ualified, heshould %e the oner since the success of the corrosion control progra! is directly related to p control.

The oner should regularly clean the pro%e ith a volatile solvent to re!ove hydrocar%on. e should alsocali%rate the syste! at least once a ee;. At so!e locations the operators chec; the syste! ith a !anualreading every day. #e have also found it to %e good practice to replace the electrodes every to !onths toprevent online failure.

I!ple!entation of these !easures has produced relia%le and accurate closed loop control syste!s.oever, our syste!s alays include one final protective !easure. The neutralier in4ection pu!p ise+uipped ith a !ini!u! pu!p rate. The pu!p rate ill not drop %elo the !ini!u! value regardlessof the instructions fro! the controller. This !easure ensures that if the pro%e or controller !alfunctions,the syste! ill still %e treated ith a !ini!u! level of neutralier.

Also, please !a;e sure the controller is ad4usting the pu!p stro;e length and not the fre+uency of thestro;e. If the controller ad4usts the stro;e fre+uency, su%stantial portions of the overhead strea! can gountreated if the pu!p is turned don drastically %y the controller.

RA075C

7nline p !eters are used successfully %y !any refiners. oever, scheduled routine !aintenance forcleaning the p pro%e is a !ust. Bather than close the loop on p control, our clients are sending a signalto the distri%uted control syste!, hich is infor!ing the operator of the p of the syste!. The high andlo p levels are alar!ed utiliing the distri%uted control alar! syste!.

:BISAC


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8r. Raco%, e have had !uch %etter luc; ith our syste!s. #e have online analyer !eters on four of ourcrude units. They have %een installed in the last one to three years. The couple that I ;no of are,Fohoa!a and Bose!ont. These have %een operating in closed loop control for several years. Instru!entshave %een operating very ell. #e do see reduced corrosion, and in our case there is little !aintenance.7perations is very pleased ith the perfor!ance of the !eters.

7n sa!ple syste!s, one refinery reports that utiliing a s!all fin-fan cooler to cool the sa!ple and the use

of larger filters is all the change they needed to !a;e to the sa!ple syste! to get it to or;.

In another refinery, they report that they have e=perienced a shortening of the pro%e life due to higherlevel of sulfides. 7verall e are very pleased ith the syste!. As I say, it is in closed loop control and eare really convinced that the corrosion in the overhead syste!s in these crude units have %een reduced.

STF2SC

#e are the guys ho do not use closed loop p control for our overhead syste!s. I guess I should first saye have had all of the pro%le!s that have %een !entioned. #e do agree that the !ore recently availa%lep pro%es are a lot !ore relia%le. oever, e did a revie of three of our crude units last year anddecided against going ith closed loop p control and the !ain reason as cost. They are fairly e=pensivesyste!s, and e have had very good luc; ith so!e si!pler syste!s.

In one refinery, they atch overhead chloride content to set their neutralier rate. In another refinery, eset the neutralier rate si!ply as a ratio of the overhead ater rate. #e have a fairly constant crude slate,so that is pro%a%ly ho e can do that. #e ad4ust the ratio %ased on a once a day p sa!ple. That hasgiven us e=cellent corrosion control.

Question *@#hat is the industry e=perience on the use of field data loggers to capture field infor!ation for unit!onitoring" 0o!!ent on specific devices used, intrinsic safety issues, personnel assigned to collect data,for!at used, etc.

2BB2:A8PC

#e have had good e=perience ith these loggers as part of our process infor!ation syste! on at least five

of our refineries. The loggers e use are sold %y 7SI. They are intrinsically safe and e=plosion proof.Typically a process operator ill ta;e the logger ith hi! on his rounds here he enters his readingsdigitally. It %asically replaces his routine cards. The logger for!at is set up to %e essentially identical tothe old !anual cards, so the operator doesnMt need to ad4ust his routine or the order in hich he !a;es hisrounds.

At the co!pletion of the round, the operator %rings the logger %ac; into the control roo! here he hoo;sit up to the co!puter and electronically donloads the data directly into the data%ase service. This thenfor!s part of our +uite ela%orate process infor!ation syste! hich also collects all the process,la%oratory, planning, target, and D80 constraint infor!ation.

266I7TTC

I ould agree ith 8r. erren;a!p that e have had success using these data loggers on a variety of

units. #e have %een pleased ith several !anufacturersL e+uip!ent. Softare provided should %e easy touse and the operator should %e a%le to append earlier data ith ne readings. The supplier should alsoprovide training in the use of the e+uip!ent and +uic; response to pro%le!s either via telephone or inperson.

PAB:C

#e have a ell developed real ti!e process !onitoring syste! called BT78S.

It has %een developed ith Infoplus softare supplied %y Aspentech.


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2very S: e!ployee can access process condition in the real ti!e %asis in his or her personal co!puter.

BT78S gathers data fro! *? process co!puters connected ith D0S, stores the! and provides data invarious ;inds of displays such a graphical ta%le. 8ost process infor!ation is captured auto!atically, %utthere is so!e field infor!ation that e have to log.

/. Product /or!ulation

Question *1In light of i!pending %ans on 8T52 or other o=ygenates, hat are the options for replacing theseco!ponents in B/G gasoline" #hat specifications ill %e !ost highly i!pacted" #hat is the pro4ectedcost to refiners"

5I66SC

7ur vie of the !atter is that the only replace!ent for the ether products ould %e ethanol. The !osthighly i!pacted specifications ill perhaps %e BP, T9@, sulfur and$or aro!atics li!itations. /i=es !ayinclude adding al;alyte or iso!erate. #e e=pect the necessary refinery !odifications, hether si!plye=panding a unit or %uilding an entirely ne one, to %e +uite costly. An even larger pro%le! !ay loo! inthe groing +uag!ire of conflict %eteen regulatory %odies, environ!ental groups and special interestgroups. These are of special interest in the light of 0aliforniaMs re+uest for an e=e!ption fro! therefor!ulated fuels o=ygenate re+uire!ent. If granted, the possi%le for!ulations for refor!ulated fuels !aydrastically change.

GATT2C

/olloing up on 8s. 5illsM co!!ents, I ould li;e to address the octane de%it issue that ould resultfro! a co!plete re!oval of o=ygenates fro! the gasoline pool. If this step is re+uired, then the %estoptions for replacing o=ygenates, as 8s. 5ills has said, are going to %e either iso!erate or al;ylate. 5othare e=cellent B/G %lendstoc;s, given their high octane values and !ini!al olefin and aro!at

1999nprasession1qa

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