AM 14 43 Tracking and Auditing Impact of New Crudes

8/21/2019 AM 14 43 Tracking and Auditing Impact of New Crudes

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American Fuel & Petrochemical Manufacturers

1667 KStreet,NW

Suite 700

Washington, DC

20006.3896

202.457.

202.457.

www.a

Annual MeetingMarch 23-25, 2014

Hyatt Regency Orlando

Orlando, FL

Presented By:

M. Scott Green

KBC Advanced

Technologies

Houston, TX

Robert Ohmes

KBC Advanced

Technologies

Houston, TX

Ralph Goodrich

KBC Advanced

Technologies

Houston, TX

Mel Larson

KBC AdvancedTechnologies

Houston, TX

.0480voice

.0486fax

pm.org


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This paper has been reproduced for the author or authors as a courtesy by the American Fuel &Petrochemical Manufacturers. Publication of this paper does not signify that the contentsnecessarily reflect the opinions of the AFPM, its officers, directors, members, or staff. Requestsfor authorization to quote or use the contents should be addressed directly to the author(s)


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TABLE OF CONTENTS

1.0 Introduction ........................................................................................................ 3

2.0 Market Background ............................................................................................ 3

3.0 Primary Refinery Impact Areas ......................................................................... 6

4.0 Crude Quality ...................................................................................................... 7

4.1 Importance of Quality ............................................................................................. 8

4.2 Critical Stream Properties and Contaminants ......................................................... 9

4.3 Quality Measurement Obstacles........................................................................... 10

5.0 Tankage/Logistics/Crude Management .......................................................... 12

6.0 Crude Compatibility ......................................................................................... 13

7.0 Crude Unit Heat Recovery ............................................................................... 15

7.1 Exchanger Fouling and Design Consideration ...................................................... 15

7.2 Exchanger Performance Monitoring ..................................................................... 16

8.0 Assay Quality and LP Maintenance ................................................................ 18

8.1 Assay Quality ....................................................................................................... 18

8.2 LP Impacts ........................................................................................................... 18

8.3 LP Maintenance ................................................................................................... 19

9.0 Unit Process and Reliability Performance Monitoring .................................. 21

10.0 Conclusions ...................................................................................................... 21

11.0 Works Cited ....................................................................................................... 23


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LIST OF FIGURES

Figure 1: Net Imports to US of Distillate and Finished Gasoline1...................................... 3

Figure 2: US Crude Oil Balance1...................................................................................... 4

Figure 3: Brazilian Fuel Outlook1...................................................................................... 5

Figure 4: US Refinery Capacity and Utilization1................................................................ 6

Figure 5: LTO Overall Impacts .......................................................................................... 7

Figure 6: US Class 1 Rail Cars of Crude Oil by Year(4)................................................... 11

Figure 7: Crude Compatibility Index vs. Blend % ............................................................ 15

Figure 8: HX-Monitor Report ........................................................................................... 17

Figure 9: HX Monitor Feed Temp Improvement Comparison .......................................... 17

Figure 10: Petro-SIM Crude/Vacuum Simulation with LP Utility ........................................ 20

Figure 11: LP Utility Swing Cuts ....................................................................................... 20

LIST OF TABLES

Table 1: Key Stream Properties and Impacts .................................................................. 9

Table 2: Crude Metals and Sources .............................................................................. 10


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1.0 Introduction

The last several years have seen refiners looking to process new crude slates in their facilities,whether it be light tight oils (LTOs) or opportunity crudes. Use of these crudes may be due toavailability of new crude sources or completion of minor and major plant modifications that allowfor processing alternate crudes. A significant undertaking in terms of manpower, analysis, andcapital is involved in evaluating the new crudes and completing projects for handling these new

sources.

Unfortunately, less effort is often spent understanding the resulting effects of the new crudes onthe facility once they are being processed than is spent on understanding their relative value.This paper examines options and makes recommendations for tracking and mitigating the short-term impact of alternate crude slates on the refinery. Furthermore, methodologies and practiceswill be suggested to assess and manage the long-term physical impact of new crudes on theplant, from both process and mechanical perspectives. That understanding is key toincorporating the lessons and key findings into the regular business processes. Case examplesare utilized to illustrate the application of these techniques.

2.0 Market Background

The market impact of light and tight oils (LTO) is now being felt globally. The combination ofrelatively flat product demand growth in the US, greatly discounted domestic crude costs, andtaxes and fees (e.g. RINS) has firmly moved the US from importing to exporting gasoline anddiesel blends. The US is now exporting jet fuel to Asia, gasoline to Africa and diesel/gasoil toLatin America and EU markets. However, the US is also importing many of those finished andrelated intermediate productsoften from the same countries.

Figure 1: Net Imports to US of Distillate and Finished Gasoline1

-1500

-1000

-500

0

500

1000

Jan-04

Jul-04

Jan-05

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Jan-06

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Jan-08

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Jan-09

Jul-09

Jan-10

Jul-10

Jan-11

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Jan-12

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Jan-13

Jul-13

kbpd

US Net Imports(Negative value indicates Export)

U.S. Net Imports of Distillate Fuel Oil 0 to 15 ppm Sulfur

U.S. Net Imports of Distillate Fuel Oil

U.S. Net Imports of Finished Motor Gasoline

Data source: US Energy Information Administration


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One clear feature of the boom in US crude production is a virtual step-for-step reduction insimilar quality crude imports. This has directly affected imports of crudes such as light Nigeria orMexican Olmeca. The result has been an indirect easing in the rest of world (ROW) globalcrude supply/demand balance. In turn, that has greatly affected crude pricing mechanismswhich, either directly or indirectly, typically price crude production against US based West TexasIntermediate (WTI) or United Kingdom, Brent crude.

Figure 2: US Crude Oil Balance1

The boom in LTO gas and crude is two-fold. First, the current and forecast long-term gasoversupply relative to demand means that in the US energy intensive processes will continue toenjoy lower cost of operations than direct competitors. In the refining business, KBC estimatesat least $1.50/bbl lower energy costs for similar complexity refiners in the US Gulf Coast vs.North West Europe.

The second advantage of the LTO boom has been dramatically lower feedstock costs for USrefiners. Under current law, US crude cannot be freely exported. Some very small exceptions

exist and are typically tied to a return of the products to the US that those crude exportsproduce. However, in fact, virtually all domestic US crude must be consumed within the US.

One now needs to recall basic macroeconomics with those supply and demand curves. In theclosed US crude system, supply has increased while demand for crude has notin truth it hasslightly, but US refinery utilization rates are already at/near historic highs. So given increasedsupply, unmoved demand and no ability to export crude, the result is a drop in price for UScrude. That price drop occurs relative to a largely constant global crude price.

0

2000

4000

6000

8000

10000

12000

ThousandB

arrellsperday

Year

US Crude Oil Balance

U.S. Field Production of CrudeOil

Data source: US Energy InformationAdministration


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Consequently, US refiners seefeedstock when they can moneUS crude production also impgeopolitical security. The geopolcrude and product to market, e.demand for finished product incinvestment.

Fig

Finally, this advantage continueincreasing production of LTOfurther increase the discount ofpointand that point is the volubreakeven costs of each barrelbut also by producer and over tthis break-even to be at/near $December 2013near $100/bblIn fact, just the opposite is happ

The challenge, therefore, for thLTO not only in short-term day-tdiscuss those shorter, tactical ilessons learned, and react appr

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massive value transfer from low priced Northize that with an export product sale. Along thoves the US-only crude supply/demand balalitical issues in other parts of the world resultin. Latin American refinery projects delayed or c

reases further enhances the US as a stable, a

ure 3: Brazilian Fuel Outlook1

s beyond fuels and into related industries suchnd shale condensates against fixed US refindomestic crude to the world market. Howeverme-weighted cost of domestic production. Likef crude production varies not only between th

ime. As guidance, KBC estimates the volume- 5/bbl. Given a global crude market trading

l, there is little chance significant US productioning.

US refiner will be to accommodate and maxi-day operations, but also strategically over thesues that need to be addressed today and hpriately to export product market opportunities.

American crudeway, increased

nce and with it,g in disruption ofanceled even asttractive area for

as plastics. Theing capacity will, this is only to amost things, thedifferent plays,

weighted bulk ofn average as ofn will be shut in.

ize the value oflonger term. Weow to document

.


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Figure 4:

3.0 Primary Refinery I

To understand the impact of Lcharacteristics. Whether compacrudes have the following gener

Highly Paraffinic Low Sulfur/Nitro Contain unusual/ Low resid conten Highly variable c

Other papers and presentationssome of these properties will be

Figure 5 provides a high-level othe operation. As indicated,

tankage/logistics, crude/vacuuprocessing units and areas are iplanning and optimization activiti

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US Refinery Capacity and Utilization1

mpact Areas

O on a refinery, one should focus on the kering Bakken, Eagle Ford, or other LTO crudl characteristics:

en/Conventional Contaminantsunconventional contaminantst, high naphtha/light-ends yieldomposition and properties

can provide more specific details on these p reviewed later in this paper.

erview of the areas in a typical refinery where many of the adversely impacted areas

unit, and the naphtha/light-end processiimpacted, but those impacts typically involve ries as opposed to resolving operating problems

y properties andsources, these

operties2,3,6, and

LTO can impactare in crude

ng units. Othergular productionand issues.


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Figure 5: LTO Overall Impacts

As refiners prepare to process new crudes, they often spend a significant amount of time,human capital, and financial capital preparing for the new feedstock. However, what is oftenlacking is the information, processes, and tools to track and manage these crudes once they arebeing processed in the facility. The remainder of this paper will focus on the following key areaswhere refiners should focus their efforts in monitoring and mitigating the adverse impact ofthese crudes on the refinery:

Crude Quality Tankage, Logistics, and Crude Management Crude Compatibility Assay Quality and LP Maintenance

Crude Unit Heat Recovery Unit Process and Reliability Performance Monitoring

4.0 Crude Quality

Tight Oil has almost come to imply a certain quality (e.g. light and sweet). While it is true thatmany tight oils do share certain similarities in characteristics, they vary in quality from field tofield and in some cases even by wells producing within a given area. The most important aspectof Quality concerned herein is expected or typical values or ranges for a given set of

physical properties versus unexpected or inconsistent. This is an important point in that, for agiven refinery asset included in a plan, adverse impacts to operations may be mitigated orminimized if crude properties received match those expected, have correspondingly beenincluded in the operations plan, and the limitations of the assets have been accurately reflected.

Strategies for analysis, work processes, and tools to ensure that the actual operationalcapability is accurately reflected are discussed in subsequent sections. These provide for amechanism to value a given crude for a corresponding asset configuration within constraints,plan and schedule accordingly, execute the plan operationally and optimize profitability. In this

Low Cost Natural Gas

CrudeFeedstock

Waxy,Fouling

Problems with cold flowproperties

Low Yields

Cracks wellHigh olefins

Low Utilization

Loweroctanes / yields

Low Rate


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section, the importance of quality is explored as well as obstacles encountered in gettingaccurate and sufficient data to evaluate and potentially plan for and process LTOs.

4.1 Importance of Quality

Why is quality, as discussed here, important? The old adage, Garbage-In, Garbage-Out(GIGO), might spring to mind. However, one refiners GIGO could be anothers opportunity to

maximize profitability with an accurately assessed crude mix and executed plan that monitorsfor and mitigates potential adverse impacts for a given quality. Accurately obtaining and auditingcrude quality (expected/typical) is important in(5):

The health/safety of personnelsome LTOs have H2S or other potentiallyhazardous substances that require mitigation (e.g. additives or planning forhandling)

Environmental additives or chemicals used in the production process couldimpact waste water treatment plants (WWTP), effluent/sour waters (e.g. solids,mercury, alkaline metals)

Planning/Scheduling compatibility with other crudes, resulting yields vs.planned yields

Economics fundamental to the evaluation of crude candidates for a given

refinery. Ultimately, this is key for determining the valuation. Operations some specifications are very sensitive to particular contaminants;

further, inaccuracies can lead to bottlenecks, blending issues, off-spec products(closely tied to Planning/Scheduling).

Reliability - unexpected characteristics may prevent specific mitigation andimpact unit run-length through unplanned outages.

Contracts - the only means for ensuring that the delivered crude is what wasbought (or means for financial adjustments ipso facto).


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4.2 Critical Stream Properties and Contaminants

A full and rigorous discussion on all the properties and contaminants that comprise the quality ofa specific crude and potentially impact the operations of a refinery is beyond the scope of thispaper. However, a high-level summary is useful to provide context on the need for refiners totrack and audit properties and contaminants. Not all impacts are negative, as some allow for

greater planning and operational flexibility. However, Tables 1 and 2 summarize key propertiesand how they may adversely impact refining operation(6).

Table 1: Key Stream Properties and Impacts

PROPERTY COMMENT IMPACT

APIAs the crude gravity approaches that of water, diluent is needed toseparate water from hydrocarbon

Water/Oil Separation

Sulfur High sulfur levels require H2and produce more H2S Corrosion

Nitrogen High nitrogen levels require H2and produce more NH3Corrosion, Support Unit

Capacity

PONA Drives gasoline/aromatic precursor yields

Affects hydrogen addition

for clean products

Metals Ni/V/Fe High catalyst replacement cycle Catalyst deactivation

Metals Na/Ca/As/Ti Alkaline metals require special guard bed catalystsCorrosion/Catalyst

deactivation

Concarbon Requires carbon rejection mechanismCatalyst deactivation and

yields

Asphaltenes Increases potential for fouling that requires shutdowns to resolve Fouling

Naphthenic Acids High levels cause corrosion Corrosion/fouling

Compatibility Certain crude and blends are incompatibleAffects allowable crude

blend and fouling

Chlorides Typically associated with alkaline metals Corrosion

Methanol Helps prevent hydrate formationWater/Oil Separation,Catalyst Deactivation

Viscosity If too high to pump, requires diluents or redesign High transportation costs


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Table 2: Crude Metals and Sources

CONVENTIONAL METALS SOURCE CONCERNS

Nickel, Vanadium In asphaltenes Natural organics Catalyst poison

Iron Iron oxides Corrosion products, sulphides

Catalyst poison,

Foulant

Silicon Polydimethylsiloxane Defoamer Catalyst poison

Arsenic As organics Natural organics Catalyst poison

EXOTIC METALS SOURCE CONCERNS

Phosphorous

Natural organics

Catalyst poisonPigging gel

Acidizing gel

Titanium With bitumen solids Naturally occurring Catalyst poison

Alkaline metals Ca, Mg, Na Naturally occurringCatalyst poison,

Foulant

Calcium stearate Flow improver Crude fouling

Mercury Naturally occurring Catalyst poison

Selenium Naturally occurring Environmental

As indicated, these properties essentially drive how a given refinery will perform and how theassets generate sustainable and reliable profitability. Therefore, understanding these propertiesand contaminants, not only in crudes but also in intermediate streams and final products, iscritical to selecting a crude slate and preparing and executing an operating plan.

4.3 Quality Measurement Obstacles

Several data sources exist to understand and estimate the properties of a given crude orrefining stream. The best way to understand a streams properties is to measure them in alaboratory. While this option may seem intuitively obvious, accurate measurement of a givenproperty is more difficult than it may initially seem. This situation is true for most crude types, butcan be more pronounced for LTOs as a function of several obstacles(5):

Dramatic increase in number of sources/crude producers (some inexperienced) Sample collection methodology inconsistent or nonexistent Systemic factors in predominant transportation modes (e.g. rail) Lack of consistency in measured property characteristics within same region or even

gathering system Difference in desired or required testing by players Availability of proximate testing service providers

With the rapid increase in production of LTOs, the number of sources and types available hasincreased and the concept of a prototype crude with a characteristic assay that is consistent isnot holding true. Crudes from the same region or even producing wells within the samegathering system can exhibit appreciable differences in measured properties. Granted, much ofthe variability may be attributable to lack of consistency in sampling methodology, standards,and logistical aspects of transportation mode (e.g. crude-by-rail). However, much of the


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inconsistency is driven by the smany refiners will have multiplvariability.

The rapid growth of crude-representative sampling of LTOterminated on US Class 1 Rail

domestic production has risen fr

Figure 6:

The sheer number of cars involv

Commingling in the rail c Stratification in rail cars Contaminants from heels Logistics prevent sampli

Sources may includaccountability/ownershi

Typical current practice is to spgive an average of the materialspecific contaminated source. Fwhere only reactive mitigationslogistical and scheduling hardshand further, if done, there may

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Data Source: Association o

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urce well as well as the point in the wells lifee versions of a given LTO crude source to

y-rail (CBR) for delivery brings logisticals. At roughly 700 barrels per car for the almoads for the first three quarters of 2013, the

om negligible to about 11% in less than three y

US Class 1 Rail Cars of Crude Oil by Year(4)

ed introduces variability and potential for the un

ars of crudes from multiple sourcesuring transportation timeleft from previous content (residuals, trash)

g each carmultiple 3rd parties (e.g. transload

t sample or use auto-samplers at delivery. Au delivered, but does not allow for isolation and i

urther, testing solely at delivery places the refiare available, if any(5,6). These may be limi

ips on an operating facility. Routine samplingbe inherent variation in procedures and pra

8459

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ted Carloads of Crude OilUS Class 1 Railroads

f American Railroads

cycle. Therefore,account for this

l challenges tost 320,000 carsrail share of US

ars

(4)

.

expected(5):

rs) with little

o-sampling doesdentification of aner in a situationited and imposet source is rare;tices at multiple

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sources. Moreover, there is a disconnect between the level and number of tests required by thesource for marketing or trading versus that of the refiner trying to proactively plan, monitor,mitigate, and optimize. There are advantages to being able to obtain representative, accurateresults at the time of loading. Some refiners have implemented this practice to give time tomitigate for results that depart from the expected. In fact, one refiner put this into practice as ameans to find the source of contamination that began to be chronic (and was trackedsuccessfully).

Presuming the previously discussed obstacles are overcome and a representative sample isobtained, the next hurdle is accurately measuring the property value. The ability of thelaboratory to measure, accurately, a property is strongly influenced by the following factors:

Availability and accuracy of the measurement equipment Training of laboratory staff and adherence to a given procedure Sample preparation and handling techniques of a given stream sample

Numerous examples exist of refiners making critical decisions based on inaccuratemeasurements of properties due to problems in these areas. Fortunately, options are growingfor service providers as the production and necessity increases.

Finally, measuring all streams and properties is not practical or cost effective. Consequently,refiners need other methods to understand a given crudes or streams properties before thecrude is purchased, let alone processed. Traditional assays have been used to provide asummary of its properties for the various boiling point cuts that exist in the crude, in addition tothe quantity of each boiling point cut(6). These assays are generated by specialty laboratoriesthat take samples of whole crude streams and complete a series of separations and tests tomeasure the amount of each cut and properties of each respective cut. The crudes are labeledby the source of the crude, such as the region or production field. Assay databases can bepurchased, generated from in-house data, or pulled from open-literature sources.Understandably, the same challenges discussed previously impact generation and validity ofcrude assays.

Refiners and crude traders can be lulled into a false sense of security and knowledge if theyassume that a given crude will have a fixed set of properties and yields continuously. In reality,the assay is a snapshot in time. Validations of crude assays and back-casting of actual versuspredicted crude properties and volumes are critical components of effective crude selection andmanagement processes and will be discussed later in Section 8.0.

5.0 Tankage/Logistics/Crude Management

The management of LTO starts at delivery and works all the way through to the feed to thecrude unit. The rail unloading system requires more personnel interaction compared to other

supply methods, thereby requiring a greater attention to safety of unloading the cars. H 2Smitigation in unloading as well as throughout the tank system is more of an issue with LTO thanconventional oils. The use of H2S scavengers is more common to address this issue. Theimpact of additives (in the field, transportation, and refining) are yet to be fully analyzed.

The tankage system size, number of tanks in service (not in turnaround), and crudecompatibility takes the forefront of the crude management and logistics. Some crudecombinations may not be acceptable or a crude may just be very high in waxy content. Tanktemperatures, frequency of turnover, mixing facilities, and even the tank floor play a role in themanagement of the crude.


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One of the concerns with processing LTOs and other non-conventional crudes is the lack ofadequate crude tankage. For example, because of the potential for incompatibility, segregationof these potentially problematic crudes becomes a high priority to avoid the precipitation ofasphaltenes. However, in the last 15 years or so, there has been a strong push to rationalizerefinery tankage to minimize both the capital and inventory costs of excessive tankage.

Today, statistical risk (Monte Carlo) simulation tools are widely used to optimize the number and

size of refinery tank facilities. Key factors taken into account when doing this analysis for crudestorage include:

Refinery complexity Crude delivery method Largest crude parcel size Days of advance and delay Pumping time (tankers) Settling time Turnarounds and other scheduled maintenance Crude blocked operations Any compulsory storage or Owners preference

Crude segregation has typically not been a parameter for this analysis unless there was aknown concern or experience that crude compatibility was going to be an issue. In addition, afewer number of larger tanks rather than a larger number of smaller tanks are often constructedto save capital costs. These factors have resulted in a number of crude tank farms that aregenerally deficient when trying to segregate challenging crudes adequately.

In the past, conventional crudes were more readily mixed either in the receiving tank or into aday tank to buffer the changes to the crude unit. The LTO requires the consideration tosegregate types of crude and to use a philosophy of in-line blending direct to the crude unit feedpump. The tank system also must account for tank heels that may be very waxy; thus,intermediate days might be required to flush a tank with a compatible solvent to recover the

lost heel volume to maximize the crude storage availability. Further, turnaround practices arebeing modified with third party companies to decrease outages from six (6) months to three (3)months or less.

Though the physical assets are important, one must remember that the staff operating thoseassets is critical for proper crude management. Training refinery tank operators to feed backwhat they experience is the first step in data collection and analysis of the source stocks toprovide a path to better understanding and adapting procedures and systems for better LTOmanagement.

6.0 Crude Compatibility

The large economic driving force to process relatively new North American developed crudescontinues to push refining companies to process these crudes to as large of an extent aspossible. These crudes include the LTOs and heavier oil sands based crude oils produced inCanada. The incentives are so large that refiners who can find a safe and effective way toprocess these crudes can plan to realize large benefits in increased profit margins. However,experience has found that the processing of these types of crudes have brought on a number ofoperating issues that need to be overcome to ensure capturing the full economic benefit.


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One of the big issues when processing these types of crudes is crude incompatibilityparticularly regarding asphaltenes precipitation. Refiners processing these opportunity crudescontinue to primarily use a reactive and experienced based strategy to deal with theincompatibility issues that can produce problems from the tank farm through the crude unitwhere stabilized emulsions can result in desalter water carryover, and increased fouling of boththe cold and hot crude preheat trains and crude heaters. Options to help mitigate compatibilityissues include:

Adjustments to the crude blending strategy Reducing the ratio of the opportunity crude to the crude blend Applying an enhanced chemical strategy including the addition of an

asphaltenes stabilizer

An additional and more proactive strategy is to analyze the asphaltene stability of theprospective crude blends. With this type of testing, a refiner can develop a crude blend stabilitydatabase that can be quite helpful in avoiding crude compatibility issues. However, theeffectiveness of this strategy relies on having enough lead-time and/or enough availabletankage for crude segregation and testing. Often this situation will not be the case, ashighlighted previously.

As an alternative, an effective predictive method based on crude assay qualities would seem tobe the best strategy to determine and avoid incompatible crude blends prior to processing themin the refinery. Fairly recent improvements in KBCs visbreaking technology has been used tosignificantly extend visbreaker run lengths by more careful feed selection thereby avoidingincompatible mixes of vacuum residue and atmospheric residue feeds.(7) One of the keyimprovements was the development of a basis for predicting unstable residue mixes for anunknown crude or crude mix.

This same technology can be used to determine the crude compatibility index (CI) for variouscrude blends. These individual crude CI values are predicted using KBCs proprietarycompatibility correlations. The figure below shows the calculated CI for Eagle Ford crude blendswith three crudes containing different levels of asphaltenes. The uppermost curve represents

the predicted CI as the ratio of the Eagle Ford crude increases when blended with a relativelylow asphaltenes, medium gravity US conventional crude. The calculated CI predicts this type ofcrude can blend with up to 50% Eagle Ford crude before it becomes a concern.

However, a refinery that normally processes a crude with similar qualities to this US basedcrude would likely want to blend the much lighter Eagle Ford crude with a heavier crude tobetter fit the refinery configuration. Thus, the medium and high asphaltenes crudes in the figurebelow represent heavier crudes that might be considered better candidates for blending withEagle Ford in terms of the resulting overall yield structure for that particular site. In this case, themedium asphaltene content crude is a lower gravity South American conventional crude whilethe high asphaltene crude is a similar gravity, non-conventional Western Canadian crude.

As the figure indicates, both of the heavier crudes show a concern for incompatibility with EagleFord crude at lower blend ratios than with the US based crude. In this example, the South

American crude blend becomes a concern with a blend approaching 40% of Eagle Ford whilethe Western Canadian crude blend becomes a concern with only a 30% blend of Eagle Fordcrude.


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Figure 7:

These potential blend limitationeconomic crudes to purchase wbelieve that a predictive tool, smaking those decisions and sutoday.

7.0 Crude Unit Heat R

7.1 Exchanger Fouling

The processing of LTOs as fepreheat exchanger fouling. Accand the resulting increase in ahigh in filterable solids that cantoday is there is not only an incrthese mechanisms are also shoexchangers.

A proposed method to predictlikely to cause an increase idescribed elsewhere.(7) Howevtechniques, methods for mitigatfouling will continue to be importits profitability. Increased foulinreduced unit throughput or even

0

4

8

12

16

20

0 20

CI

Com

Concern

Likely Not Com

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Crude Compatibility Index vs. Blend %

should be accounted for when determining when trying to optimize refinery production andch as the one shown here, can be a very valplementing the active testing methods that refi

ecovery

and Design Consideration

ed to crude units has resulted in an increaslerated preheat fouling can be caused by cruphaltene precipitation as discussed previousl

lso cause an increased rate of fouling. What rease in exchanger fouling in the hot end of the

wing up and increasing the fouling rate in the

eat exchanger performance when processingexchanger fouling through the two mech

er, even with the use of state-of-the-art fing and/or reducing the overall economic impant to the refiner to ensure their operating facilg not only increases operating costs, but ca shutdown for exchanger cleaning.

40 60 80

% Eagle Ford in Blend

atibility Index vs % in Blend

Low Medium High

patible

Compatible

hat are the mostprofitability. KBCuable means forners are utilizing

ed tendency fore incompatibility. LTOs are alsofiners are findingpreheat train, butold preheat train

crudes that arenisms above isuling predictionct of exchanger

ity can maximizen also result in

100


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From a design perspective, a few improvements in exchanger design may be helpful to mitigatefouling. First, there is an increased interest today to design exchangers with higher tube andshell-side velocities, eliminate dead areas, etc., to reduce the fouling tendency.8,9Traditionalexchanger designs are typically based on using fouling factors recommended by the TubularExchanger Manufacturers Association (TEMA), perhaps with some modifications based onexperience. This more current no or low fouling type of design attempts to significantly reducethat historical built-in fouling factor that overdesigns exchangers, which tends to self fulfill the

higher degree of fouling.

For existing crude preheat exchangers, it may be possible, for example, to retrofit TwistedTube bundles into existing exchanger shells or, if required, new shell and tubes can beordered. This baffle-free design essentially eliminates the dead spots while also providing moreefficient heat transfer. Other types of exchanger designs, such as helical-baffle, can also beconsidered to help reduce the shell-side dead zones and thereby reduce fouling.

Of course, the number of refiners that will be adding new exchangers or can justify retrofittingexisting crude preheat exchangers will be in the minority. Most refiners, certainly in the nearterm, will have to rely on their existing exchanger equipment and deal with the fouling issues asbest as they can.

7.2 Exchanger Performance Monitoring

The most effective way to maintain an existing crude preheat train operating at its economicoptimum is by using an automated monitoring tool. Unfortunately, many refineries do not havethat capability and instead rely on simpler and less effective techniques. These techniquesinclude conducting basic temperature/pressure surveys and then using that data to determinethe amount of fouling that is occurring by tracking the loss in heat transfer. More often than not,this will be done using a relatively simple spreadsheet. This type of tool will not likely have thecapability of dynamically and holistically determining what the impact of cleaning one or moreexchangers will have on the improvement of the fired heater coil inlet temperature. Instead, therefiner will have to rely on experience assuming good historical records are maintained.

One commercially available monitoring tool is KBCs HX Monitor, a heat exchanger monitorutility in Petro-SIM. This utility tracks the exchanger fouling by linking to the existing operatingand laboratory data, as well as the data historian. Using these data, it then generates theeconomic benefits of cleaning an exchanger or series of exchangers versus the loss ofproduction and cleaning costs. Since the preheat train exchangers are linked, the model willdetermine the direct impact of the cleaning on the heater COT, thereby eliminating anyguesswork. The preheat network can also be linked with the crude and vacuum column modelswhere, for example, it can account column operating changes including stream rate/propertychanges, pumparound heat removal restrictions, and other performance variables.

Examples of the typical types of HX Monitor reports are shown in the figures below. The firstshows a detailed breakdown of the payback for cleaning each of the exchangers in the network.

It also shows the impact of combining two of the exchangers for cleaning. In this second case,the model shows that cleaning both exchangers will provide a payback in a little over threeweeks with an expected increase in heater coil inlet temperature of 17C.


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Figure 8: HX-Monitor Report

This next figure is an example of how the data can be plotted. In this case, the improvement infired heater coil inlet temperature is plotted against exchanger(s) being cleaned.

Figure 9: HX Monitor Feed Temperature Improvement Comparison

Plots such as these as well as the other more detailed data displayed above are quite usefulinformation that can be readily inserted into operating or management reports. They provide avery clear picture of the cost versus benefits of cleaning exchangers that should help simplify

the decision making process.


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8.0 Assay Quality and LP Maintenance

8.1 Assay Quality

The LTO oils have greater variability than typical conventional crude sources. In the past thecrude oil field depletion or change was slow enough that getting a detailed sample and analysistoday was sufficient for the next 5 years. This situation is not true of the unconventional or LTO.

The variety or variability of Eagle Ford, Bakken, Marcellus, and Utica crudes, to name a few, isquite diverse. The economic model used to plan and set strategies within the typical refinery isthe linear program (LP). The inputs to the LP are detailed assay analysis of the crude source.

The unconventional oil molecular make up is quite different from the conventional oils, withsubstantially lower sulfur, nitrogen, metals and higher paraffin and isoparaffin concentrations.Recent work with detailed hydrocarbon analysis (DHA) of condensates indicates that, fromproduction formation to formation, different concentrations of PIANO (paraffin, isoparaffin,aromatic, naphthene, olefin) exist. One implication of this difference is that the naphtha reformerunits yield performance and severity requirements can be quite different. Obviously, as theparaffin concentration increases and/or aromatics decrease, the cracking severity changes aswill the C5+ yield and octane. Therefore, having accurate assay information is critical to

planning and managing the refinery operation. Similar issues exist with properties such asfreeze point in jet fuel, cloud and pour point in diesel, and metals and concarbon for gasoils.

Sampling and analysis of crude receipts at the refinery gate is one means to track and get anidea of the changes that will be made and impact to production and schedules. As previouslymentioned, if there are incompatibilities of various crude sources, the impact or limitation to co-processing must be addressed in the LP to reflect the economics of operations.

8.2 LP Impacts

The need to review and update the LP vectors with the advent of LTO is becoming aproblematic area for many refiners. With a steady diet of consistent crudes, many refiners wouldonly need to update the LP vectors periodically due to significant changes in unit performanceor the introduction of new operating envelopes. Given the large variability in crude properties, inLTO, the LPs should be reviewed and updated more frequently.

Key in this effort is the backcasting or look-back auditing of the month-to-month operation ofeach unit in the refinery against LP predictions. Unit-by-unit feed and yield analysis, combinedwith the LP predictions, identifies gaps between the LP and reality. These gaps may beoperational and/or yield related, thereby requiring analysis on whether to include or exclude inLP modifications and updates.

The lower sulfur LTO and unconventional oils, in light of upcoming Tier 3 specificationmandates, improve the refiners ability to meet the gasoline sulfur specification. The lower feedsulfur and higher paraffinic nature reduce the severity demands and, at the FCC, increase the

conversion. From a sulfur management basis, it is a welcome feedstock, but from theperspective of octane generation, it is more of a challenge. Therefore, the LTO assay and unit-by-unit representation with more restrictive fuels specifications highlights the need to be vigilantwith incoming feed tracking, unit mass/properties balances, and LP representation.


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Finally, the LP tool is used in conjunction with the scheduling tool to produce and ship variousgrades of gasoline as well as meeting jet and diesel movements. The variability of the LTO andfeed quality variation can have an impact on fouling that may impede meeting production targetsand thus shipping schedules. The tighter specification on Tier 3 gasoline will force refiners totighten up on the giveaway or margin between finished specs and pipeline or pumpspecifications. The lower the margin at the blend point, the lower the margin in unit operationsupstream. These examples, again, highlight the need for tracking / updating and maintaining the

LP in a more on-line and real-time basis than has been needed in the past.

8.3 LP Maintenance

Several options exist to provide updates of an LP(10,11,12), including:

Reconciled plant data with controlled test runs Licensor or vendor data Pilot plant data Generic correlations Rigorous process simulations with kinetic models

Many refiners are now gravitating to the use of process simulations with kinetic models toprovide updated LP unit submodels, especially when updating the shift vectors. Although thismodel based approach does require at least one heat and material balance of the process unitto set up and calibrate the model, this approach has several advantages over the alternatemethods listed above:

Less intensive on refining staff and process units to complete step tests andplant data reconciliation

Ability to predict performance more rapidly than completing test runs Improved accuracy compared to generic correlations Typically more cost effective than pilot plant tests, as well as the ability to mirror

unit configuration, feature, and performance aspects such as fractionation

efficiency Ability to maintain and utilize the tool within the organization, thereby reducingreliance on third parties for performance data

Capability to leverage tools for other purposes in engineering and design

As an example, a simplified Petro-SIM model of a Crude/Vacuum is used to demonstrate theconcept. In this case, the unit consists of a preflash tower, main fractionator, and vacuum unit(Figure 10). The model is calibrated and set up to fit the units configuration and separationefficiency. The KBC LP Utility is utilized to take crude assays from a crude assay database,process the crudes through the unit simulation, and automatically generate LP tables that canbe directly imported into the LP model platform of choice. The user can include both real cutsand swing cuts and generate most common refining properties for these cuts, as deemednecessary to understand the change in cutpoints on refinery operation (Figure 11). These swingcuts can be changed or modified as the users deem necessary and the entire crude assaydatabase processed through the model and into LP tables in just a matter of minutes. This sameapproach can be used on downstream units, and the LP Utility will allow the user to perturbateother unit performance variables, such as FCC riser temperature, hydrotreater sulfur target, orreformer severity, to name a few.


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Figure 10: Petro-SIM Crude/Vacuum Simulation with LP Utility

Figure 11: LP Utility Swing Cuts

By applying a tool like an LP Utility, the refiner can quickly and efficiently update the LP crudeassay tables and unit submodels to reflect current and potential operating conditions. Thiscapability is particularly important for refiners processing LTO, as the crude qualities and unitoperating conditions can change significantly, as LTO is processed in the facility. By improvingthe accuracy of the LP model, the refiner can confidently make the necessary crude purchasingand unit operating strategy decisions.


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9.0 Unit Process and Reliability Performance Monitoring

As highlighted in several areas above, the need for and criticality of unit performance monitoringhas become a more important issue when processing LTO. Most refiners have some platformunit performance and health monitoring tools, whether it be via tracking spreadsheets,dashboards, or monitoring tools linked to simulation models (13). Whichever platform a refinerchooses, increased processing of LTO provides an opportunity for the refinery personnel to

review the information, targets, and KPIs (key performance indicators) monitored by theseapplications.

Best practice for unit performance monitoring is to review the contents of these tools on a yearlybasis or as required when significant changes in unit operation occur. Most refiners shouldinclude this review as part of conventional management of change (MOC) processes. Sinceprocessing LTO can significantly impact a units operating conditions, the refiner should reviewthe operation against accepted operating envelopes. In some cases, the unit may be operatingat higher or lower throughput, different temperature profiles, or with different yield patterns,thereby potentially going beyond accepted operating envelopes. Therefore, the monitoring toolshould not only track these critical variables but also ensure the high/low limits are aligned withdefined operating envelopes, design conditions, and accepted practices within the facility.

The following lessons learned are offered for consideration as part of ensuring unit healthmonitoring is occurring properly:

Do not just focus on conventional process variables. Make sure one takes into accountreliability related KPIs and process variables that impact reliability.

Utilize a cross functional team to complete a cold eyes review of the monitoredvariables and limits set within monitoring application.

Ensure the KPIs are clearly defined and prioritized such that the users understand therequired next steps to return the variable to the proper performance region.

Check the accuracy of instrumentation used directly as monitored variables as well asthe calculations and correlations used to create KPIs.

The tendency of many refiners is to gravitate to the impacts of LTO processing on yields andproduct qualities. However, the refiner should not forget the impact of LTO on equipmentreliability, such as compressor performance, exchanger fouling, metal corrosion, andmaintenance practices.

10.0 Conclusions

In summary, processing LTO provides a great opportunity for US refiners to leverage cost and

location advantaged crudes with existing plant capabilities. As refiners evaluate, value, andprocess these crudes, they should focus on tracking and understanding how the crudes areimpacting the refinerys performance. Some of the critical areas include:

Crude quality monitoring Tankage and logistics management Compatibility of LTO with others crudes processed in the facility Exchanger fouling monitoring LP assay and model maintenance Unit process and reliability monitoring


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Several options and techniques exist to ensure the refiner can address these issues andcapture the full economic benefit of processing LTO.


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11.0 Works Cited

1 Energy Information Administration Website, February 2014, www.eia.gov

2 Sayles, S. and M. Routt, Unconventional Crude Oil Selection and Compatibility, NPRA Annual Meeting, March 2011.

3 Sayles, S., Unconventional Crude Processing Part 2: Heteroatoms, Crude Oil Quality Association (COQA), October 2010.

4 Association of American Railroads, Moving Crude Oil by Rail, December 2013.

5 Weimer, Gary, Crude by Rail Quality Issues, Crude Oil Quality Association June 2013 Meeting.

6 Ohmes, R. and Routt, M., Characterizing and Tracking Contaminants in Opportunity Crudes, AFPM Annual Meeting, March2013.

7 Sayles, S. and Romero, S., Case History: Characterization of Shale Oils and Heat-Exchanger Performance, HydrocarbonProcessing, February 2014

8 Bott, T Reg, To Foul or Not to Foul, Chemical Engineering Progress, November 2001

9 Nesta, J. and Bennett C. A., Reduce Fouling in Shell-and-Tube Heat Exchangers, Hydrocarbon Processing, July 2004

10 Tucker, Michael A., LP Modeling Past, Present, and Future, NPRA 2001 Computer Conference, CC-01-153.

11 Tucker, Michael and Crespo, Ihali, Upgrade and Applications for the PEMEX National Refining System LP Model, AFPM Q&AMeeting, October 2013.

12 Kidd, Nigel, LP Model Data Development using Simulation Models, Haverly MUG 2013 Conference, September 2013.

13 Ohmes, Robert, Developing and Enabling the Next Generation of Refinery Process Engineers, AFPM Annual Meeting, March2012.

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AM 14 43 Tracking and Auditing Impact of New Crudes