FW UOP Visbreaking Process

CHAPTER 12.3FW/UOP VISBREAKING

PROCESS

Kenneth M. Negin and Fred M. Van TineFoster Wheeler USA Corporation

Clinton, New Jersey

INTRODUCTION

Visbreaking is a well-established noncatalytic thermal process that converts atmosphericor vacuum residues to gas, naphtha, distillates, and tar. Visbreaking reduces the quantityof cutter stock required to meet fuel oil specifications while reducing the overall quantity offuel oil produced.

The conversion of these residues is accomplished by heating the residue material tohigh temperatures in a furnace. The material is passed through a soaking zone, locatedeither in the heater or in an external drum, under proper temperature and pressure con-straints so as to produce the desired products. The heater effluent is then quenched with aquenching medium to stop the reaction.

With refineries today processing heavier crudes and having a greater demand for dis-tillate products, visbreaking offers a low-cost conversion capability to produce incremen-tal gas and distillate products while simultaneously reducing fuel oil viscosity. Visbreakingcan be even more attractive if the refiner has idle equipment available that can be modifiedfor this service.

When a visbreaking unit is considered for the upgrading of residual streams, the fol-lowing objectives are typically identified:

● Viscosity reduction of residual streams which will reduce the quantity of high-quali-ty distillates necessary to produce a fuel oil meeting commercial viscosity specifica-tions.

● Conversion of a portion of the residual feed to distillate products, especially crackingfeedstocks. This is achieved by operating a vacuum flasher downstream of a visbreakerto produce a vacuum gas oil cut.

● Reduction of fuel oil production while at the same time reducing pour point and viscos-ity. This is achieved by utilizing a thermal cracking heater, in addition to a visbreakerheater, which destroys the high wax content of the feedstock.

Specific refining objectives must be defined before a visbreaker is integrated into arefinery, since the overall processing scheme can be varied, affecting the overall eco-nomics of the project.

12.91

COIL VERSUS SOAKER DESIGN

Two visbreaking processes are commercially available. The first process is the coil, orfurnace, type, which is the type offered through Foster Wheeler and UOP. The coilprocess achieves conversion by high-temperature cracking within a dedicated soakingcoil in the furnace. With conversion primarily achieved as a result of temperature andresidence time, coil visbreaking is described as a high-temperature, short-residence-timeroute. Foster Wheeler has successfully designed many heaters of this type worldwide.

The main advantage of the coil-type design is the two-zone fired heater. This typeheater provides for a high degree of flexibility in heat input, resulting in better control ofthe material being heated. With the coil-type design, decoking of the heater tubes isaccomplished more easily by the use of steam-air decoking.

Foster Wheeler’s coil-type cracking heater produces a stable fuel oil. A stable visbro-ken product is particularly important to refiners who do not have many options in blend-ing stocks.

The alternative soaker process achieves some conversion within the heater. However,the majority of the conversion occurs in a reaction vessel or soaker which holds the two-phase effluent at an elevated temperature for a predetermined length of time. Soaker vis-breaking is described as a low-temperature, high-residence-time route. The soaker processis licensed by Shell. Foster Wheeler has engineered a number of these types of visbreak-ers as well.

By providing the residence time required to achieve the desired reaction, the soakerdrum design allows the heater to operate at a lower outlet temperature. This lower heateroutlet temperature results in lower fuel cost. Although there is an apparent fuel savingsadvantage experienced by the soaker-drum-type design, there are also some disadvantages.The main disadvantage is the decoking operation of the heater and soaker drum. Althoughdecoking requirements of the soaker drum design are not as frequent as those of the coil-type design, the soaker design requires more equipment for coke removal and handling.

The customary practice of removing coke from a drum is to cut it out with high-pres-sure water. This procedure produces a significant amount of coke-laden water which needsto be handled, filtered, and then recycled for use again. Unlike delayed cokers, visbreak-ers do not normally include the facilities required to handle coke-laden water. The cost ofthese facilities can be justified for a coker, where coke cutting occurs every day. However,because of the relatively infrequent decoking operation associated with a visbreaker, thiscost cannot be justified.

Product qualities and yields from the coil and soaker drum design are essentially thesame at a given severity and are independent of visbreaker configuration.

FEEDSTOCKS

Atmospheric and vacuum residues are normal feedstocks to a visbreaker. Theseresidues will typically achieve a conversion to gas, gasoline, and gas oil in the order of10 to 50 percent, depending on the severity and feedstock characteristics. This willtherefore reduce the requirement for fuel oil cutter stock. The conversion of the residueto distillate and lighter products is commonly used as a measurement of the severity ofthe visbreaking operation. Percent conversion is determined as the amount of 650°F+(343°C+) material present in the atmospheric residue feedstock or 900°F+ (482°C+)material present in the vacuum residue feedstock which is visbroken into lighter boil-ing components.

The extent of conversion is limited by a number of feedstock characteristics, such asasphaltene, sodium, and Conradson carbon content. A feedstock with a high asphaltene con-

12.92 VISBREAKING AND COKING

FW/UOP VISBREAKING PROCESS 12.93

tent will result in an overall lower conversion than a normal asphaltene feedstock, while main-taining production of a stable fuel oil from the visbreaker bottoms. Also the presence of sodi-um, as well as higher levels of feed Conradson carbon, can increase the rate of coking in theheater tubes. Minimizing the sodium content to almost a negligible amount and minimizingthe Conradson carbon weight percent will result in longer cycle run lengths.

Variations in feedstock quality will impact the level of conversion obtained at a specif-ic severity. Pilot plant analyses of a number of different visbreaker feedstocks have shownthat, for a given feedstock, as the severity is increased, the viscosity of the 400°F+(204°C+) visbroken tar initially decreases and then, at higher severity levels, increases dra-matically, indicating the formation of coke precursors.

The point at which this viscosity reversal occurs differs from feed to feed but typicallycoincides with approximately 120 to 140 standard cubic feet (SCF) of C3 � gas produc-tion per barrel of feed (20.2 to 23.6 normal m3/m3). It is believed that this reversal in vis-cosity defines the point beyond which fuel oil instability will occur. Fuel oil instability isdiscussed in the next section of this chapter, “Yields and Product Properties.”

The data obtained from these pilot tests have been correlated. The viscosity reversalpoint can be predicted and is used to establish design parameters for a particular feedstockto avoid the formation of an unstable fuel oil, while maximizing conversion.

Pilot plant work has also been done relating visbreaker heater run length to conversionand feedstock quality. Figure 12.3.1 graphically represents the decrease in heater runlength with increasing feedstock conversion. This graph has been plotted with data forthree atmospheric residues with varying feed Conradson carbon. Figure 12.3.1 shows that,for a given percent conversion, as the feed quality diminishes (i.e., as Conradson carbongrows higher), coking of the heater tubes increases, resulting in shorter run lengths.

It has been found that visbreaking susceptibilities bear no firm relationship with APIdensity, which is the usual chargestock property parameter utilized in thermal crackingcorrelations. However, feedstocks with low n-pentane insolubles and low softening pointsshow good susceptibility to visbreaking, while those having high values for these proper-

FIGURE 12.3.1. Relative run length versus conversion atvarious feed qualities.

ties respond poorly. Figure 12.3.2 shows the capability of greater conversion at lower n-pentane insolubles for a 900°F+ (482°C+) vacuum residue.

Residues with low softening points and low n-pentane insolubles contain a greater por-tion of the heavy distillate, nonasphaltenic oil. It is this heavy oil that cracks into lowerboiling and less viscous oils which results in an overall viscosity reduction. Theasphaltenes, that fraction which is insoluble in n-pentane, goes through the furnace rela-tively unaffected at moderate severities. The table below shows the typical normal pentaneinsolubles content of vacuum residues prepared from base crudes.

Crude-type source Range of n-pentaneof vacuum residue insolubles, wt %

Paraffinic 2–10Mixed 10–20Naphthenic 18–28

YIELDS AND PRODUCT PROPERTIES

Product stability of the visbreaker residue is a main concern in selecting the severity ofthe visbreaker operating conditions. Severity, or the degree of conversion, if improperlydetermined, can cause phase separation of the fuel oil even after cutter stock blending.As previously described, increasing visbreaking severity and percent conversion will ini-tially lead to a reduction in the visbroken fuel oil viscosity. However, visbroken fuel oilstability will decrease as the level of severity—and hence conversion—is increasedbeyond a certain point, dependent on feedstock characteristics.


FIGURE 12.3.2. Visbreaking susceptibility (900°F+ chargeconverted).

Until a few years ago, fuel oil stability was measured using the Navy Boiler andTurbine Laboratory (NBTL) heater test. The NBTL test was the accepted test to meas-ure fuel oil stability. However, in the late 1980s there was a general consensus that theNBTL test did not accurately measure fuel oil stability and therefore American Societyfor Testing and Materials (ASTM) discontinued the test in 1990. Refiners today use theShell hot filtration test or some variation of it to measure fuel oil stability.

Sulfur in the visbroken fuel oil residue can also be a problem. Typically the sulfur con-tent of the visbreaker residue is approximately 0.5 wt % greater than the sulfur in the feed.Therefore it can be difficult to meet the commercial sulfur specifications of the refineryproduct residual fuel oil, and blending with low-sulfur cutter stocks may be required.

The development of yields is important in determining the overall economic attractive-ness of visbreaking. Foster Wheeler uses its own in-house correlations to determine yielddistributions for FW/UOP visbreaking. Our correlations have been based on pilot plantand commercial operating data which allow us to accurately predict the yield distributionfor a desired severity while maintaining fuel oil stability. A typical visbreaker yield dia-gram showing trends of gas and distillate product yields as a function of percent conver-sion is presented in Fig. 12.3.3.

Also note in Fig. 12.3.3 that, as the percent conversion increases, the gas, gasoline, andgas oil product yields also increase. However, the conversion can be increased only to acertain point before risking the possible production of an unstable fuel oil. It should alsobe kept in mind that, at higher percent conversion, some of the gas oil product will furthercrack and be converted into gas and gasoline products. This will occur particularly whenhigh conversion is achieved at higher heater outlet temperatures.

In Table 12.3.1 we provide typical feed and product properties for light Arabian atmo-spheric and vacuum residues. These yields are based on a standard severity and single-passvisbreaking while producing a stable visbroken residue. It should be noted that the result-ant yield distribution for either a coil or soaker visbreaker is essentially the same for thesame conversion.


FIGURE 12.3.3. Typical yield trend, gas and distillate prod-ucts.

OPERATING VARIABLES

The main operating variables in visbreaking are temperature, pressure, and residence time.Increasing any one of these three variables will result in an increase in overall severity. Toachieve a certain severity, these variables can be interchanged within limits. For a given sever-ity, as measured by conversion, product distribution and quality are virtually unchanged.

An increase in yields of distillate and gaseous hydrocarbons can be achieved byincreasing visbreaking severity—for example, by raising the heater outlet temperature.Increasing visbreaker severity will also result in a reduction of cutter stock required tomeet fuel oil specifications. However, the higher severities will cause the heavy distillateoils to break down and crack to lighter components. These heavy distillate oils act to sol-ubilize (peptize) the asphaltic constituents. The asphaltic constituents will then tend to sep-arate out of the oil and form coke deposits in the furnace tubes. Visbreaker operation at thislevel can cause premature unit shutdowns. There is also a tendency to produce unstablefuel oils at these more severe conditions.

PROCESS FLOW SCHEMES

Presented in this section are three visbreaking process schemes, with a diagram and ageneral description of each:

1. A typical visbreaker unit (Fig. 12.3.4)

2. A typical visbreaker unit with vacuum flasher (Fig. 12.3.5)

3. A typical combination visbreaker and thermal cracker (Fig. 12.3.6)


TABLE 12.3.1 Typical Yields and Product Properties

Light Arabian Light ArabianFeed properties atmospheric residue vacuum residue

Density, °API 15.9 7.1Density, kg/m3 960 1021Conradson carbon, wt % 8.5 20.3Sulfur, wt % 2.95 4.0Viscosity, cSt:

At 130°F (54°C) 150 30,000At 210°F (99°C) 25 900

Estimated yields wt % °API kg/m3 S, wt % wt % °API kg/m3 S, wt %

H2S 0.2 0.2C3 � 2.0 1.5C4’s 0.9 0.7C5–330°F (C5–166°C) 7.9 57.8 748 0.54 6.0 57.8 748 0.6330–600°F (166–316°C) 14.5 36.5 842 1.34 15.5* 33.3 859 1.7600°F+ (316°C+) 74.5 13.5 976 3.48 76.1† 3.5 1048 4.7

100.0 100.0

*330–662°F (166–350°C) cut for Light Arabian vacuum residue.†662°F+ (350°C+) cut for Light Arabian vacuum residue.

FIG

UR

E 1

2.3.

4.P

roce

ss s

chem

atic

for

typ

ical

vis

brea

ker

unit

. (Fo

ster

Whe

eler

and

UO

P.)

12.97

FIG

UR

E 1

2.3.

5.P

roce

ss s

chem

atic

for

typ

ical

vis

brea

ker

unit

wit

h va

cuum

fla

sher

. (Fo

ster

Whe

eler

and

UO

P.)

12.98

FIG

UR

E 1

2.3.

6.P

roce

ss s

chem

atic

for

com

bina

tion

vis

brea

ker

and

ther

mal

cra

cker

. (Fo

ster

Whe

eler

and

UO

P.)

The first is the most basic scheme, the other two schemes being expanded versions. Figure12.3.7 is a photograph of a visbreaker designed and built by Foster Wheeler in Spain.

Typical Visbreaker Unit

A typical visbreaker (Fig. 12.3.4) can be employed when viscosity reduction of resid-ual streams is desired so that the need for high-quality distillate cutter stock can bereduced in order to produce a commercial-grade residual fuel oil.

The visbreaker unit is charged with atmospheric or vacuum residue. The unit charge israised to the proper reaction temperature in the visbreaker heater. The reaction is allowedto continue to the desired degree of conversion in a soaking zone in the heater. Steam isinjected into each heater coil to maintain the required minimum velocity and residencetime and to suppress the formation of coke in the heater tubes. After leaving the heatersoaking zone, the effluent is quenched with a quenching medium to stop the reaction andis sent to the visbreaker fractionator for separation.

The heater effluent enters the fractionator flash zone where the liquid portion flows tothe bottom of the tower and is steam-stripped to produce the bottoms product. The vaporportion flows up the tower to the shed and wash section where it is cleaned and cooled witha gas oil wash stream. The washed vapors then continue up the tower. Gas oil stripper feed,as well as pumparound, wash liquid, and the gas oil to quench the charge are all removedon a side drawoff tray. The pumparound can be used to reboil gas plant towers, preheatboiler feedwater, and generate steam. The feed to the gas oil stripper is steam-stripped, andthen a portion of it is mixed with visbreaker bottoms to meet viscosity reduction require-ments; the remainder is sent to battery limits.

The overhead vapors from the tower are partially condensed and sent to the overheaddrum. The vapors flow under pressure control to a gas plant. A portion of the condensed


FIGURE 12.3.7. Visbreaker designed and built by Foster Wheeler in Spain.

hydrocarbon liquid is used as reflux in the tower and the remainder is sent to a stabilizer.Sour water is withdrawn from the drum and sent to battery limits.

Typical Visbreaker Unit with Vacuum Flasher

The flow scheme for this configuration (Fig. 12.3.5) is similar to the first schemeexcept that the visbreaker tower bottoms are sent to a vacuum tower where additionaldistillate products are recovered. This scheme may be desirable since a portion of theresidual feed is converted to a cracking feedstock.

In this scheme, the visbreaker bottoms are sent to the vacuum tower flash zone. The liq-uid portion of the feed falls to the bottom section of the tower, where it is steam-stripped. Thevapor portion rises through the tower wash section and then is partially condensed into dis-tillate products. On this process flow diagram, we have shown two side draws. On the low-er drawoff, heavy vacuum gas oil (HVGO) product and pumparound along with wash oil arewithdrawn. On the upper one, light vacuum gas oil (LVGO) and reflux are withdrawn. LVGOand HVGO are then combined to form a single vacuum gas oil product which, after vis-breaker fuel oil viscosity reduction requirements are met, can be used as a cracker feedstock.

The overhead vapors from the vacuum tower flow to a three-stage vacuum ejector sys-tem. Condensed vapor and motivating steam are collected in a condensate accumulator.

Typical Combination Visbreaker and Thermal Cracker

This last scheme is similar to the second except that the vacuum gas oil is routed to athermal cracker heater instead of to battery limits as a product (Fig. 12.3.6). The vacu-um gas oil is cracked and then sent to the visbreaker fractionator along with the vis-breaker heater effluent.

A thermal cracking heater is utilized with a visbreaker when maximum light distillateconversion is desired or where extreme pour point reduction is required. Products from thislast configuration are a blend of heavy vacuum tar and visbreaker atmospheric gas oil, plusa full range of distillates. Extreme pour point reduction is required for cases in which ahigh wax content feedstock is processed. The total conversion of the visbreaker vacuumgas oil essentially destroys all of the wax it contains, thus drastically reducing the pourpoint of the resulting visbreaker fuel oil.

REACTION PRODUCT QUENCHING

In order to maintain a desired degree of conversion, it is necessary to stop the reactionat the heater outlet by quenching. Quenching not only stops the conversion reaction toproduce the desired results, but will also prevent production of an unstable bottomsproduct. For a coil-type visbreaker, quenching of the heater outlet begins from approx-imately 850 to 910°F (454 to 488°C) depending on the severity. The temperature of thequenched products depends on the overflash requirements and the type of quenchingmedium used. The overflash requirements are set by the need to maintain a minimumwash liquid rate for keeping the visbreaker fractionator trays wet and preventing exces-sive coking above the flash zone. Typically, the temperature of the quenched productsin the flash zone will vary between approximately 730 and 800°F (388 and 427°C).

Quenching can be accomplished by using different mediums. The most frequently usedquenching mediums are gas oil, residue, or a combination of both. These are discussed


below. The decision as to which quenching medium is to be used must be made very ear-ly in a design. This decision will greatly affect the unit’s overall heat and material balanceas well as equipment sizing.

Gas oil is the most prevalent medium used for reaction quenching. The gas oil quenchworks primarily by vaporization and therefore requires a smaller amount of material tostop the conversion reaction than a residue quench. The gas oil quench promotes additionalmixing and achieves thermal equilibrium rapidly. The residue quench operates solely bysensible heat transfer rather than the latent heat transfer of the gas oil quench.

The gas oil quench is a clean quench and thus minimizes the degree of unit fouling. Itis believed that the use of a residue quench gives way to fouling in the transfer line andfractionator. Also the visbreaker bottoms circuit, from which the residue quench origi-nates, is in itself subject to fouling. The gas oil quench arrangement increases the vaporand liquid loadings in the tower’s flash zone, wash section, and pumparound. This willresult in a larger tower diameter than if residue quench was used alone.

In order to achieve the same reaction quenching, residue quench flow rates need to begreater than for gas oil quenching. This, as noted above, is because gas oil quenches the reac-tion by vaporization and residue quenches by sensible heat. In addition, the quenching dutygoes up as the percentage of residue quench increases. The actual quenching duty increasesbecause more residue is required in order to achieve the same enthalpy at the flash zone. Theuse of residue quench means more tower bottoms, product plus recycle, are processed.

Residue quenching provides the potential for additional heat recovery within the unitat a higher temperature level than gas oil quenching. For example, heat recovery from arecycle residue stream may be between 680 and 480°F (360 and 249°C), while heat recov-ery for a gas oil stream may be from 620 to 480°F (327 to 249°C). With the increase invisbreaker bottoms, additional residue steam stripping is required, which also increases thesize of the overhead condenser.

Some visbreaker units designed by Foster Wheeler and UOP employ a combination ofboth gas oil and residue quenching. It has been found for several visbreaker designs thatusing a combination quench rather than 100 percent gas oil will shift a significant amount ofavailable heat from steam generation, in the gas oil pumparound, to feed preheat. This is nor-mally preferred as it results in a smaller visbreaker heater and minimizes utility production.

Selection of a combination quench system is preferred for its overall unit flexibility.However, it is more expensive because of duplication of cooling services on the residueand gas oil circuits. It is believed, however, that additional cooling is advantageous sincethe visbreaking operation can continue by shifting gas oil/residue requirements, even ifexchangers in the residue circuit become fouled. These exchangers can be bypassed with-out excessive turndown.

Additionally, the residue and gas oil quench can be used to vary the fractionator flashzone temperature. In visbreaking, many refiners try to keep the flash zone temperature aslow as possible in order to minimize the potential for coking. When evaluating the flashzone temperature for a fixed overflash, increasing the percentage of residue will reducethis temperature. The flash zone could vary by as much as 50°F (28°C) between theextremes of total gas oil and residue quench. Figure 12.3.8 shows the basic relationship ofthe quench feed temperature to the flash zone as a function of the percentage of the reac-tion quench performed by residue quench. The total reaction quench duty as a function ofpercent quench by residue for a fixed overflash is also shown.

HEATER DESIGN CONSIDERATIONS

The heater is the heart of the coil-type visbreaker unit. In the design of its visbreakers,Foster Wheeler prefers using a horizontal tube heater for FW/UOP visbreaking to


ensure more uniform heating along the tube length. A horizontal-type heater allows theflow pattern for each pass to be as symmetrical as possible. Overheating of one passcan result in thermal degradation of the fluid and eventual coking of that pass.Horizontal-type heaters are also preferred since they have drainable type systems, andliquid pockets cannot develop as in vertical type heaters.

For the coil-type design, the heater is designed with two independently fired zones. Thefirst is a preheat cell which heats the feed to reaction temperature, approximately 800°F(427°C). The second is a reaction cell which provides the heat input and residence timerequired for the desired reaction. The visbreaking reaction continues as the fluid leaves thefurnace, where it is stopped by quenching. Figure 12.3.9 shows a typical temperature curvefor the preheat and reaction zones of a visbreaker heater. This figure shows an 865°F(463°C) heater outlet temperature; however, this temperature can be over 900°F (482°C),depending on the severity of the operation.

In order to achieve the desired residence time in the heater, coil volume in the reactionsection is very important. The coil volume will directly affect the cost of the heater. Thecoil volume specified by Foster Wheeler in designing these heaters is based on previousexperience and operating data. During operation, the residence time can be adjusted bycontrolling the heat input to the reaction cell, the back-pressure on the heater, and theinjection steam rate.

Visbreaker heaters typically have a process preheat coil and a steam superheat coil inthe convection section. The steam coil is used for superheating steam for residue and gasoil stripping. Steam generation is normally not required in the heater convection section,since the visbreaker produces steam in its bottoms and pumparound circuits.

The heater tube metallurgy is specified as 9% Cr–1% Mo for the main process coil inboth the radiant and convection sections. This material is required because of the high


FIGURE 12.3.8. Quench parameters: quench feed temperature andduty versus residue quench.

heater outlet temperature, regardless of the weight percent sulfur in the feed. Steam super-heat coils are usually specified as carbon steel.

Foster Wheeler and UOP typically specify a normal (clean) pressure drop of approxi-mately 300 lb/in2 gage (20.7 bar gage) and a dirty (fouled) pressure drop of approximate-ly 400 lb/in2 gage (27.6 bar gage). The elastic design pressure of the heater tubes is basedon the shutoff pressure of the charge pump at maximum suction. Some refiners use a reliefvalve, located at the heater outlet, to lower the design pressure required for the tubes.Foster Wheeler and UOP do not rely on a relief valve in this service, as the inlet to thevalve tends to coke up.

Turndown on a visbreaker heater is typically limited to 60 percent of design capacity.On some projects, clients have installed two heaters, which provide greater unit turndowncapability. The additional heater also allows decoking of one heater without shutting downthe unit. A two-heater visbreaker may be economically justified for larger units.

The visbreaker heater can be fired on fuel gas, fuel oil, or visbreaker tar. It is economi-cally attractive to fire the visbreaker heater on visbreaker tar since no external fuel sourcewould be needed. However, tar firing requires correctly designed burners to avoid problemsof poor combustion. The burners typically require tar at high pressure and low viscosity.Therefore the tar system needs to be maintained at a higher temperature than a normal fueloil system. Although refiners may prefer to fire the heater with visbreaker tar, many are beingforced to burn cleaner fuel gases so as to comply with environmental regulations.


FIGURE 12.3.9. Heater temperature curve.

TYPICAL UTILITY REQUIREMENTS

The following represents typical utility consumptions for a coil-type visbreaker:

Power, kW/BPSD [kW/(m3 � h) feed] 0.0358 [0.00938]

Fuel, 106 Btu/bbl (kWh/m3 feed) 0.1195 (220)

Medium-pressure steam, lb/bbl (kg/m3 feed) 6.4 (18.3)

Cooling water, gal/bbl (m3/m3 feed) 71.0 (1.69)

ESTIMATED INVESTMENT COST

Estimated capital costs for a coil-type visbreaker without vacuum flasher or gas plantare $17 million in 10,000 BPSD (66.2 m3/h) capacity and $33 million in 40,000 BPSD(265 m3/h) capacity.

These are conceptual estimates with ±30 percent accuracy. They apply to battery-lim-its process units, based on U.S. Gulf Coast, second quarter 2002, built according to instantexecution philosophy, through mechanical completion only. The estimates assume thatland is free of aboveground and underground obstructions. Excluded are cost of land,process licensor fees, taxes, royalties, permits, duties, warehouse spare parts, catalysts, for-ward escalation, support facilities, and all client costs.

BIBLIOGRAPHY

Allan, D., C. Martinez, C. Eng, and W. Barton, Chemical Engineering Progress, p. 85, January 1983.

McKetta, J., and W. Cunningham, “Visbreaking Severity Limits,” Petroleum Processing Handbook,Marcel Dekker, New York, 1992, p. 311.

Rhoe, A., and C. de Blignieres, Hydrocarbon Processing, p. 131, January 1979.


Date post:	11-Nov-2014
Category:	Documents
Upload:	studyendless
View:	337 times
Download:	20 times

FW UOP Visbreaking Process

Documents