KBR-Economic Extraction of FCC Feedstock From Residual Oils

National Petrochemical & Refiners Association 1899 L Street, NW Suite 1000 Washington, DC 20036.3896

202.457.0480 voice 202.429.7726 fax www.npra.org

Annual Meeting March 19-21, 2006 Grand America Hotel Salt Lake City, UT

AM-06-18 Economic Extraction of FCC Feedstock

From Residual Oils

Presented By: Phillip Niccum Chief Technology Engineer, FCC KBR Houston, TX Rick Northup Process Manager, Heavy Oil Upgrading KBR Houston, TX

This paper has been reproduced for the author or authors as a courtesy by the National Petrochemical & Refiners Association. Publication of this paper does not signify that the contents necessarily reflect the opinions of the NPRA, its officers, directors, members, or staff. Requests for authorization to quote or use the contents should be addressed directly to the author(s)

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Economic Extraction of FCC Feedstock from

Residual Oils

Phillip K. Niccum Chief Technology Engineer – FCC

and

Aldrich H. Northup

Process Manager – Heavy Oil Upgrading

Kellogg Brown & Root LLC Houston, Texas, USA

Abstract

Increasing differential cost between light and heavy crude oils and increasing demand for re-fined petroleum products have led to a surge in new deasphalting unit installations. Deasphalt-ing units allow refiners to either switch to heavier, less expensive crude oils or to dig deeper into bottom of the barrel, at minimum investment cost. The deasphalting process is particularly adept at producing good quality FCC feedstock from highly contaminated crude oils because the selective partitioning of contaminants between the deasphalted oil and asphaltene fraction is favorable for contaminants that are the most detrimental to FCC operations, e.g. metals > carbon residue > nitrogen > sulfur. The right combination of solvent deasphalting followed by the FCC will offer new opportunities in improving profitability to refiners.

Distillation, deasphalting, and fluid catalytic cracking unit pilot plant data are presented that contrast the processing of atmospheric residue in an FCC unit with the processing of deasphalted oil. The data show that deasphalting produces more FCC feedstock from each barrel of crude processed while also providing a less contaminated FCC feedstock compared to the processing of incremental atmospheric residue. The net result is increased production of refined products and reduced FCC catalyst consumption relative to catalytic cracking of residue.

While the aforementioned synergies between deasphalting and FCC have been known for many years, recent advancements in deasphalting technology and new options for asphaltene product utilization have broadened the appeal of the process.

Economic Extraction of FCC Feedstock from Residual Oils

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Introduction

Heavy refinery crude oil feedstocks are generally more aromatic than lighter feedstocks. In the past, aromatic crude oils were not preferred because of their poor lubricating properties and resistance to conversion in cracking units and because aromatics are generally associated with the worst elements of crude oil - contaminants such as vanadium, nickel, nitrogen and sul-fur. Much of the investment and operating cost associated with a modern petroleum refinery revolves around separation of the heavier aromatics and associated contaminants from the more desirable constituents of crude oil.

Since heavy aromatics are concentrated in the highest boiling fraction of crude oil, the first line of defense has traditionally been to fractionate out the higher boiling fraction of the crude oil, selling the residue at a price well below that of more desirable petroleum products. However, as crude oil supplies and refinery capacity have tightened relative to the demand for refined products, refiners are investing in technology to recover valuable hydrocarbons once lost with the residue.

Today, many of the processes that are used to recover more valuable hydrocarbons from resi-due are processes that have been around for more than 60 years – including solvent deasphalting and fluid catalytic cracking. Advancements in these technologies together with changing market conditions and a better understanding of the process synergies have lead to renewed interest in the use of these technologies for residue upgrading.

Crude Supply and Product Demand Trends

Increasing global demand for refined products has led to an unprecedented increase in market price for crude oil and refined products. The price levels are supported by tight supplies of crude oil and high refinery utilization rates. Unlike past trends the expectation is that these pric-ing levels will be maintained due in large part to the growth in demand among large emerging economies such as China and India. An excellent article by the IMF provides an analysis of the pricing mechanisms in the oil market and reasons for current and future high prices.1

The price differential be-tween light and heavy crude oil has also increased in the last few years. Based on historical trends this differ-ential price is greater than expected from increased crude price alone. Histori-cal differentials are ex-pected to increase in the future.2

Historical crude oil produc-tion trends indicate an in-crease in production of heavier crudes and de-crease in production of lighter crudes. Data ex-

Orthoflow™ FCC

Figure 1: Word Crude Production Quality

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

1992 1994 1996 1998 2000 2002 2004 2006

Year

Per

cent

of

Wor

ld C

rude

Pro

duct

ion 26-35 API

35 plus API

10-26 API

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

1992 1994 1996 1998 2000 2002 2004 2006

Year

Per

cent

of

Wor

ld C

rude

Pro

duct

ion 26-35 API

35 plus API

10-26 API

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

1992 1994 1996 1998 2000 2002 2004 2006

Year

Per

cent

of

Wor

ld C

rude

Pro

duct

ion 26-35 API

35 plus API

10-26 API

Source: ENI Group, Worldwide Oil and Gas Review 2005


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tracted from a report by the ENI Group 3 provides some insight into this trend. ENI compared the worldwide production of light (35+ºAPI), medium (26-35ºAPI) and heavy (10-26ºAPI) cru-des over the time period of 1994 – 2004. Over this time period the production of light crude oil decreased from 31% to 29% of total world production. The production of heavy crude oil in-creased from 11% to 14% of total world production. Figure 1 provides a graphical view of these trends.

The market trends, pricing and production patterns discussed in the previous paragraphs pro-vide economic and strategic incentives for the refiner to consider bottom-of-the barrel projects to allow processing heavy crudes so they can enjoy the economic benefits of reduced feed-stock costs. Indeed, the increase in number of both grassroots and new coker projects over the last few years points to the increased interest in processing heavier lower cost crudes.

This paper presents information on a bottom-of-the barrel processing option that utilizes sol-vent deasphalting to extract incremental FCC feedstock from a crude oil. This process con-figuration can be used as presented or combined with other options, such as coking, to pro-vide increased utilization of heavy residues.

ROSE® Solvent Deasphalting

Solvent extraction was intro-duced in the 1930’s as a means of extracting paraffinic lube oil blending stocks from mixed base and naphthenic crude oils. After widespread implementation of fluid cata-lytic cracking, refiners soon recognized the negative im-pact on FCC yield perform-ance from processing aro-matic extracts. Recognizing opportunity, soon thereafter refiners turned to solvent ex-traction as a means of produc-ing viable FCC feedstock from residue that was otherwise too contaminated for economic FCC processing. It was discovered that residual oils could be “decarbonized” with propane solvent to produce FCC feeds with sufficiently low concentrations of carbon residue and metals to allow economic processing in the FCC units.4 In the 1970’s, Kerr McKee developed a solvent deasphalting process, the ROSE Process, that separates most of the solvent from the deasphalted oil (DAO) in the supercritical phase regime rather than utilizing energy intensive boil-off and condensation for solvent recovery.5 The supercritical solvent recovery breakthrough greatly reduced the utilities expense associated with operation of the units, and the ROSE process quickly became the dominant residue deasphalting proc-ess. ROSE technology was acquired by The M.W. Kellogg Company in 1995 and now it is part of the refining technology portfolio offered by Halliburton subsidiary Kellogg Brown & Root LLC (KBR).

Orthoflow™ FCC

Figure 2: 30,000 BPSD ROSE UnitSimple and Compact


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Fluid Catalytic Cracking

Many companies contributed to the development of fluid catalytic cracking, but chief among these were The M.W. Kellogg Company and Standard Oil of New Jersey, now KBR and ExxonMobil.6 The development culminated in 1942 with Kellogg building the world’s first FCC unit for Standard Oil in Baton Rouge, Louisiana followed by Kellogg building an additional 21 FCC units during the next two years. In a post-war economy, the emphasis in FCC turned from high octane gasoline production at any cost to the optimization of yields and the utilization of lower quality feedstocks. Residue Fluid Catalytic Cracking marked a milestone in 1961 with a purpose built residue feedstock FCC unit design by Kellogg for Phillips Petroleum Company that in-cluded steam gener-ating coils within the regenerator bed to remove excess heat.7 It was, however, not until the oil embargo and skyrocketing oil prices of the 1970’s that residue fluid catalytic cracking began to gain wider acceptance as a vi-able option for up-grading selected residues into more valuable products.

Residue FCC Feedstock Considerations

Feed properties that are most important to consider when processing residue in an FCC unit are (1) vanadium, which is the controlling parameter setting FCC catalyst make-up rates, (2) carbon residue which is the major factor affecting coke burning and catalyst cooling require-ments, and (3) hydrogen content which impacts FCC conversion and yield selectivity.

Residues with lower concentrations of carbon residue and metals, particularly paraffinic, low vanadium crude oils, are naturally better suited to upgrading in FCC units, and often significant volumes of such residues or even 100 percent atmospheric residue can be charged to FCC units with little or no changes to the FCC hardware. However, the availability of these high quality crude oils is diminishing and more contaminated, heavier crude oils are making up an increasing proportion of the worlds crude oil supply.

Even if blended in small concentrations into FCC feedstocks, residues from lower quality crude oils often contain higher concentrations of metals and carbon residue than would be economic for FCC processing because of the contaminant’s impact on required catalyst make-up rate and FCC yields; therefore before processing in the FCC unit, the residues from

Orthoflow™ FCC

Figure 3: 1950’s Vintage FCC UnitMeeting the demand for motor gasoline


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such crude oils must first be upgraded with such processes as vacuum dis-tillation, coking, residue hydrotreating or solvent deasphalting to reduce carbon residue and metals content.

• While directly proc-essing residue from some high quality crude oils in the FCC unit can be economic, this op-tion is not very flexi-ble with respect to refinery crude oil supply.

• Vacuum distillation can separate vacuum gas oil from atmospheric residue, but vac-uum distillation leaves potential FCC feed behind in the vacuum residue.

• Coking eliminates vanadium and carbon residue from its gas oil products but the coker gas oils are hydrogen deficient, resulting in poor yield selectivity when processed in an FCC unit.

• Residue hydrotreating can reduce contaminants to economic levels while increasing FCC feed hydrogen content but the capital and operating costs of residue hydrotreat-ing are high.

ROSE solvent deasphalting separates a less contaminated, hydrogen rich material (DAO) from atmospheric or vacuum residue that can be economically cracked in an FCC unit, miti-gating issues associated with the processing schemes described above. The increased hy-drogen content and lower contaminants of the DAO relative to the residue together with low investment and operating costs often makes ROSE an economical option for producing good quality FCC feed from residue.

It is interesting to note as shown in Figure 4 that the contaminants that are most detrimental to the FCC unit operation are also the ones that show the sharpest partitioning in the ROSE unit. e.g. metals > carbon residue > nitrogen > sulfur, resulting in a natural synergy between these processes.

Pilot Plant Study

The KBR Technology Development Center in Houston, Texas includes among its many pilot plant operations, distillation, ROSE solvent deasphalting, and fluid catalytic cracking. Refer to the appendix for a description of the units. These facilities were used to evaluate three refinery options for processing Alaskan North Slope (ANS) atmospheric tower bottoms (ATB) in an existing refinery.

Orthoflow™ FCC

Figure 4 - DAO Quality Control

% COMPONENT IN DAO

100

80

60

40

20

00 10 20 30 40 50 60 70 80 90 100

DAO YIELD, VOL %

METALS

SULFUR

NITROGEN

CCR


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• VGO FCC - The base configuration utilizes vacuum distillation to produce vacuum gas oil (VGO) which is fed to an FCC unit. This scheme represents a conventional process-ing route and results in the least amount of ATB upgrading.

• VGO/ATB FCC – The second option bypasses some ATB around the vacuum distilla-tion unit and blends it with the VGO feeding the FCC unit.

• VGO/DAO FCC – The third option utilizes a ROSE solvent deasphalting unit extract DAO from the available residue and blends it with VGO feeding the FCC unit.

Distillation and Feedstock Blending

A vacuum distillation (steam assisted atmospheric distillation) of Alaskan North Slope ATB was carried out producing 45.0 vol% vacuum residue and 54.2 vol% vacuum gas oil at nomi-nal 950 °F+ cut point for further processing in the ROSE and FCC pilot plant. After distillation to obtain the VTB and VGO fractions, a ROSE feed blend was made from the VTB and re-maining ATB. The composition of the ROSE pilot plant feed blend (51.6 vol% vacuum residue and 48.4 vol% ATB) simulates the intention of the refinery to maintain the operation of the vac-uum distillation unit at maximum rate while routing additional ATB directly to a ROSE unit along with the available vacuum residue.

It is noted that blending ATB and vacuum residue upstream of the ROSE unit will yield about the same overall results in the pilot plant study as would have been obtained from proc-essing all the ATB in the vacuum tower and then sending all the vacuum residue to the ROSE unit because the ROSE unit captures essentially all the vacuum gas oil in the DAO product. Similar overall results would have been obtained if all the ATB had been processed directly through the ROSE unit with no vacuum distillation.

After operation of the ROSE pilot plant to produce quantities of the desired DAO, the DAO was blended with VGO to produce feedstock for the FCC pilot plant.

A third FCC feed was made from blending some of the original ATB and the VGO. The com-position of the VGO/ATB FCC feed blend was chosen to provide an FCC feed Conradson Carbon Residue (CCR) and metals representing reasonable maxima for a conventional FCC unit.

Rose® Solvent Deasphalting

The ROSE feedstock was processed in preliminary runs of the ROSE pilot plant with the ob-jective of producing both a maximum DAO yield and a less than maximum DAO yield with n-butane solvent at an 8:1 solvent-to-oil ratio. These runs began with the extraction temperature above the expected temperature for maximum extraction conditions. The temperature was gradually lowered to increase the DAO yield. Maximum extraction operating conditions for the solvent were identified when the DAO yield no longer increased as the Asphaltene Separator (extraction) temperature was decreased. The maximum DAO yield was found to be 78 wt%, and a less than maximum DAO yield was taken at 67 wt%.

The maximum and less than maximum DAO yield runs were then used to establish a relation-ship between DAO yield and quality. Table 1 presents the preliminary run results and esti-mates of the DAO quality for intermediate DAO yields. Based on these data, a DAO produc-tion run at 74 wt% yield was selected as the target for production of the FCC pilot plant feed-stock. The 74 wt% DAO yield was selected because it was close in yield to the maximum ex-traction 78% yield, while the CCR and metals were significantly less. The contaminant level of


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the 4% incremental DAO from 74 to 78 wt% yield was estimated to contain 24 wt% CCR, 26 wppm nickel and 46 wppm vanadium. From an economic perspective, this 4 wt% fraction was believed best left in the asphaltene fraction due to its depressing effect on conversion of the balance of the FCC feed and its expected negative impact on FCC catalyst consumption. The final production run data are also included in Table 1, showing good agreement with what had been expected based on the preliminary results.

TABLE 1

ROSE Screening Runs - DAO Quality Summary

DAO Yield Case

CCR, wt%

Ni, ppm

V, ppm

78 wt% yield (preliminary run)

5.1

5.6

6.0

74 wt% yield (estimate)

4.1

4.5

3.8

71 wt% yield (estimate)

3.6

4.0

2.9

67 wt% yield (preliminary run)

3.2

3.6

2.1

74 wt% yield (production run)

4.4

4.5

3.6

Table 2 presents the ROSE pilot plant feedstock and product properties from ROSE pilot plant operations at 74 wt% DAO yield along with the properties of the ROSE unit feed compo-nents and VGO for reference.


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ROSE and FCC Feed/Product Inspections

Identification AR/VRAtm Vacuum Vacuum Blend ROSE ROSE

Resid Gas Oil Resid ROSE Feed DAO Pitch

API 15.2 21.7 7.6 11.3 16.8 -4.4Distillation Type D.1160 D.1160 D.1160 GCSD GCSD

IBP 0F 506 469 875 486 466 -- 5 % 618 615 953 704 653 -- 10 682 664 983 795 729 -- 20 746 718 1053 922 828 -- 30 798 750 1099 1008 911 -- 40 851 786 -- 1092 976 -- 50 912 811 -- 1186 1035 -- 60 982 833 -- 1300 1096 -- 70 1088 864 -- -- 1168 -- 80 -- 895 -- -- 1267 -- 90 -- 934 -- -- -- -- 95 -- 973 -- -- -- -- EP 0F -- 1032 -- -- -- --Total Sulfur, WT% 1.86 1.10 2.11 1.95 1.49 3.26Total Nitrogen, WT% 0.39 0.15 0.61 0.53 0.34 1.01Hydrogen WT% -- -- -- 12.31 13.05 9.85CCR, WT% 8.8 0.38 18.3 13.4 4.43 38.8C5 Insolubles, WT% -- -- -- 10.2 <0.10 45.20C7 Insolubles, WT% -- <0.10 -- 4.9 <0.10 23.4Metal: Nickel PPM 24 1.0 45 36 4.5 126Vanadium PPM 52 0.7 98 81 3.6 301

TABLE 2

Fluid Catalytic Cracking

The FCC pilot plant was run on three feedstocks, 100% VGO and blends of VGO with either ATB or DAO. For operation of the pilot unit, some basic guidelines were established. Tem-perature settings for the riser were based on an isothermal target of 970 °F. Dispersion nitro-gen was held at the equivalent of 5 wt% steam in the feed. Rather than adding fresh make-up catalyst to maintain catalyst activity, the unit's catalyst inventory was replaced after each set of runs on a single feed. Table 3 contains a summary of the FCC pilot plant data.


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TABLE 3 FCC Pilot Plant Summary

970 °F and 7:1 catalyst-to-oil ratio FCC Pilot Plant Feedstock Case

VGO

VGO + ATB

VGO + DAO

FCC Feed Components

VGO, vol% 100 63 43

ATB, vol% 0 37 0

DAO, vol% 0 0 57

BBL of FCC Feed/ 100 BBL of ATB 54.2 65.3 85.3

FCC Feed Properties

API Gravity, degrees 21.7 19.5 18.5

50 vol% boiling point, F 811 836 901

Aniline Point, F 168 179 180

K Factor 11.73 11.63 11.75

Sulfur, wt% 1.10 1.44 1.32

CCR, wt% 0.38 3.4 2.5

Metals (Ni+V), ppm 1.7 28.2 5.5

FCC Pilot Plant Yields

Dry Gas, wt% 2.4 2.8 2.9

C3 LPG, vol% 10.5 9.2 9.1

C4 LPG, vol% 15.7 14.4 13.4

Gasoline, vol% 58.6 55.9 56.2

Light cycle oil, vol% 16.9 16.3 17.3

Slurry oil, vol% 8.4 11.7 11.9

Coke, wt% 5.1 7.2 6.5

C3+ liquids, vol% 110.1 107.5 107.9

Conversion, vol% 74.7 72.0 70.8

The data contained in Table 3 clearly demonstrates the advantage of using ROSE to produce incremental FCC feed relative to processing of ATB directly in the FCC unit. As shown, the


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ROSE case produces substantially more FCC feed per barrel of ATB. Another compelling yet simple set of evidence supporting this conclusion can be seen by noting the high average boil-ing point and corresponding high Watson K for the DAO containing feed relative to that of the ATB containing feed while the DAO case contaminant levels are considerably less.

In a commercial FCC unit, the most striking differences between the VGO/DAO feedstock and the VGO/ATB feedstock, aside from the difference in feed volume available to the FCC unit, will be the effects of the metals on catalyst make-up rate and catalyst selectivity characteristics. Estimates of commercial FCC catalyst make-up requirements and equilibrium catalyst properties for each of the FCC pilot plant feedstocks are shown below in Table 4 for reference along with the properties of the catalyst actually used in the FCC pilot plant study.

TABLE 4 Estimated Commercial FCC Catalyst Characteristics

VGO

VGO + ATB

VGO + DAO

FCC Pilot Plant Catalyst

FCC Feed Metals, ppm

Ni 1.0 9.2 3.4

V 0.7 19.0 2.1

Fresh Catalyst Make-Up, lb/bbl FCC Feedstock

0.12

1.14

0.25

Equilibrium FCC Catalyst

Ni, ppm 2710 2650 4550 2230

V, ppm 1900 5478 2810 3600

MAT Activity, vol% 69 69 69 69

Overall Unit Balance And Summary

The overall balance of feeds and products from the three processing options are presented in Figures 6, 7 and 8. The VGO FCC option summarized in Figure 6 utilizes vacuum distillation to produce vacuum gas oil which is then used as FCC feed. This scheme represents a con-ventional processing route and results in the least amount of ATB upgrading. It displays 56.0 BPD of combined LPG, gasoline and distillate and a combined FCC slurry and vacuum resi-due production of 49.6 BPD per 100 BPD of ATB.


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By-passing ATB around the vacuum distillation unit and adding it to the VGO to the extent palatable to the FCC unit provides in-cremental ATB upgrading. This processing option is shown in Figure 7. For this option, about 24 percent of the ATB bypasses the vacuum distillation unit. This flow scheme results in a combined LPG, gaso-line and distillate rate of 63.0 BPD from 100 BPD of ATB and a combined FCC slurry and vacuum residue production of 41.7 BPD. One of the costs of the improvement in the balance relative to the previous option would be a large increase in FCC catalyst consumption, e.g. 3.2 TPD for the VGO feed option v.s. 37.2 TPD for this case assuming 100,000 BPD of ATB input.

Adding a ROSE unit to the refining configuration as shown in Figure 8 pro-vides a very large in-crease in feed available to the FCC unit relative to either of the other two con-figurations. FCC feed quality is also improved compared to the VGO/ATB FCC flow scheme. This scheme produces a combined LPG, gasoline and distil-late rate of 82.4 BPD from 100 BPD of ATB, and a combined FCC slurry and ROSE asphaltene produc-

tion of 24.3 BPD. At the same time, the estimated FCC catalyst consumption is a manage-able 10.7 TPD assuming 100,000 BPD of ATB input.

Figure 9 shows a graphical comparison of the product yields for each processing option. The option that involves processing VGO only in the FCC results in the highest yield of fuel oil components (49.6 BPD). The greatest reduction in fuel oil production is achieved with the processing option that includes ROSE solvent deasphalting with 24.3 BPD of fuel oil per 100 BPD of ATB. The option based on charging VGO and some ATB to the FCC offers only a moderate reduction in fuel oil production (49.6 to 41.7 BPD) compared to the VGO FCC feed

Orthoflow™ FCC

Figure 6: VGO FCC Block Flow Diagram

North SlopeAtmos. Resid VACUUM

DISTILLATIONUNIT

100 BPD

100 BPD

0.8 BPD

54.2 BPD21.7 OAPI0.38 wt% CCR1.7 ppmw Ni + V

VGO54.2 BPD

FCC UNIT

C2- + H2 S

C3

- C

4

C5 - 430

430 - 650

650+

COKE950 oF+

2.4* wt%

14.2 BPD

31.8 BPD

9.2 BPD

4.6 BPD

5.1* wt%

Vacuum Residue45.0 BPD

* yield on FCC feed

Orthoflow™ FCC

Figure 7: VGO+ATB FCC Block Flow Diagram


DISTILLATIONUNIT

100 BPD

75.9 BPD

24.1 BPD

0.6 BPD

65.2 BPD19.5 OAPI3.4 wt% CCR28 ppmw Ni + V

VGO41.1 BPD

FCC UNIT

C2

- + H2S

C3 - C4

C5 - 430

430 - 650

650+

COKE950 oF+

2.8* wt%

15.4 BPD

36.4 BPD

10.6 BPD

7.6 BPD

7.2* wt%

Vacuum Residue34.1 BPD

* yield on FCC feed


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processing configuration. The configurations with the lowest production of re-sidual fuel, also enjoy the highest yield of the more valuable (C3 – 650 °F) products. However, a case can be made against the processing of con-taminated atmospheric residue d irectly in the FCC unit based not only on the high FCC catalyst con-sumption but also be-cause the loss of FCC yield performance with the heavier feedstock may be too great considering the

limited amount of residue upgrading that was achieved. For instance, the total liquid volume including the 650 °F + fraction for the complex is lowest when processing ATB directly on the FCC unit, with overall product volumes of 105.6 vol%, 104.7 vol% and 106.7 vol% respectively for the three process configurations.

Orthoflow™ FCC

Figure 8: VGO+DAO FCC Block Flow Diagram


DISTILLATIONUNIT

ROSE UNIT

100 BPD

61.3 BPD

29.7 BPD

70.3 BPD

0 BPD

0.6 BPD

Asphaltenes14.2 BPD

85.2 BPD18.5 OAPI1.3% S2.5 wt% CCR5.5 ppmw Ni + V

DAO47.1 BPD

VGO38.1 BPD

FCC UNIT

C2- + H2S

C3 - C4

C5 - 430

430 - 650

650+

COKE950 oF+

31.6 BPD

2.9* wt%

19.2 BPD

47.9 BPD

14.7 BPD

10.1 BPD

6.5* wt%

* yield on FCC feed

Orthoflow™ FCC

14.2 15.419.2

31.836.4

47.9

10.0 11.215.3

49.6

41.7

24.3

56.063.0

82.4

0102030405060708090

100

VGO FCC VGO+ATB FCC VGO+DAO FCC

LV

% Y

IEL

D

C3-C4 C5-430 430-650 650+ C3-650

Figure 9: Overall Product Yields From ATBfor three different process configurations


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ROSE Technology Advancements Advances in ROSE unit hardware technology together with expanding options for asphal-tene product utilization have led to an increased rate of new ROSE unit installations during the past several years as summarized below. ROSEMAX™ and LUBEMAX™

Recent advances in supercritical separator design have led to the development of improve-ments in solvent deasphalting technology that have been incorporated into ROSE units offered by KBR. These improvements in separation technology, developed in conjunction with Koch-Glitsch Inc, are incorporated in KBR’s proprietary separators.8 Purpose-designed internals are provided to address the special needs for a ROSE unit producing lube base stocks or a ROSE unit producing DAO for conversion feedstock.9

LUBEMAX™ internals are utilized in ROSE units that produce lube base stock. These units typically produce very high quality DAO at relatively low yield. LUBEMAX technology is a tray-type solution that offers superior yield and quality benefits compared to other low superficial velocity solutions such as Rotating Disk Contactors (RDC), packing or other tray types. The following process gains are expected for a typical application:

• 20 – 30% capacity increase in capacity compared to RDC columns

• 2X increase in mass transfer efficiency

• 0.5 – 1.0% DAO yield increase

LUBEMAX trays are designed to carefully manage the flow of light and heavy phase liquids in order to minimize undesirable backmixing. The design technique is the key to providing im-proved capacity and efficiency compared to other design alternatives.

ROSEMAX™ extraction internals primarily address the specific needs of ROSE unit intended to produce DAO for use as conversion feedstock. These units must extract deeply to obtain a high yield of DAO while maintaining a reasonable level of contaminants (typically carbon resi-due and metals). Maximizing throughput for a given vessel diameter is o ften a significant ob-jective for these units. ROSEMAX internals represent a structured packing based solution to achieve very high capacity while maintaining low impurity levels. Typical benefits provided by ROSEMAX internals compared to random packing are:

• 20 – 30% increase in capacity

• 1%+ increase in DAO yield at maximum extraction

• 7-10% improvement in quality at constant yield.

Asphaltene Utilization Options

Economic utilization of the asphaltene product from a ROSE unit is the key to ROSE process economics. Listed below are some of the options refineries are utilizing to maximize the value of ROSE asphaltene product followed by a discussion of each option:

• Fuel oil blend component

• Specialty commercial asphaltenes

• Conversion (coker) feedstock


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• Partial oxidation feedstock

• Solid fuel

Asphaltene product to fuel oil - It is sometimes possible to burn the asphaltene product di-rectly as fuel oil, but in most cases, it is first blended with other low-value streams to produce a lower viscosity product that meets fuel oil specifications. The fuel oil production can often be cut to less than half by installing a ROSE unit and blending asphaltenes instead of vacuum re-siduum into fuel oil.

Some refiners blend the asphaltenes with distillate materials to produce No. 6 fuel oil. Light cycle oil and slurry oil from the FCCU makes excellent blending stocks because of their high aromatic content. A visbreaker can be used to reduce the viscosity of the asphaltene and thus reduce the required amount of blending stock. However, the high sulfur content of the asphal-tene may limit its use in No. 6 fuel oil production.

Asphaltene quality depends on crude slate, and as the crude slate becomes heavier and more sour, the asphaltene produced from these crude oils will also contain a higher quantity of sulfur. Environmental regulations will therefore dictate how much flue gas cleanup is required and, hence, the viability of direct firing burning of asphaltenes.

Commercial asphaltenes - Specialty products, such as paving asphalt or roofing asphalt, can be made by blending the ROSE asphaltenes with suitable aromatic oils.

Asphaltene coking - Refiners are now successfully cracking asphaltenes in their cokers. Nor-mally asphaltene is blended with vacuum residuum to achieve good flow properties. The blend is then cracked in cokers. Asphaltene cracking is being carried out by both delayed and fluid coker operators. Cracking ROSE asphaltene instead of vacuum residuum reduces total coke make by 10-20%. The liquid yield also improves. At the 2003 NPRA some refiners reported use of more than 50 percent asphaltenes in their coker feedstocks.10

KBR has processed asphaltene in our coker pilot plant. Typical pilot plant yields from coking the asphaltenes are provided in Table 5 below.

Table 5

Data from KBR Delayed Coker Pilot Plant Feed

Source Pentane asphaltene

Conradson carbon, wt% 38

Yields, wt%

Gas 6.9

C3-C3 3.8

C5-400°F 12.1

400-650°F 16.4

650°F+ 15.0

Coke 45.8


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Note that the coke yield is much less than would be expected from a traditional feed with high CCR. The ratio of feed CCR to coke yield is about 1.2 for this feedstock. Lower CCR feed-stocks can be expected to have a feed CCR to coke yield ratio of 1.5 to 1.6 under similar con-ditions.

Asphaltene to partial oxidation unit - The asphaltene can be fed to a partial oxidation unit to produce synthesis gas. Hydrogen in the synthesis gas can be used for hydroprocessing units. The remaining synthesis gas is fired to produce steam and power. There are presently two ROSE units in operation feeding partial oxidation units and three more planned as the prime outlet for their asphaltene product.

Solid fuel - There are existing commercial technologies to produce solid fuel from the solvent asphaltene. However, these processes are generally high in maintenance, low in reliability and are manpower intensive. The new AQUAFORM™ process offered by KBR produces solid pel-lets that are stable, can be stored and are easily transportable. The pellets have high heating value and low attrition rates. The solid fuel produced from heavy and sour oils will be high in sulfur. Therefore, it can be used only in boilers with stack-gas cleanup or in fluidized-bed boil-ers that use limestone to capture sulphur oxides from the combustion products. The potential users of these pellets are cement, steel, partial oxidation units (gasifiers), cokers, and utility companies.

Increasing ROSE Demand

The convergence of market forces and improvements in ROSE technology and associated asphaltene utilization options have led to a significant increase in licensed ROSE unit capacity as shown in Figure 10. During just the four year period from 2005 through 2008, ten new ROSE units with a total capacity of over 260,000 BPSD are expected to come on stream.

FCC Design for Heavy Feedstocks

Residue FCC units must deal with feed compo-nents contaminated with nickel, vanadium, and Con-radson Carbon Residue (CCR). While each of these contaminants affect the performance of the unit in different ways, the latter two present the more sig-nificant challenges to the design and operation of the FCC unit.

CCR in the feed increases amount of coke deposited on the catalyst as it passed through the riser. This is often referred to as “delta coke” and increasing delta coke can lead to high re-generator temperature, reducing FCC feed conversion due to lowering of catalyst to oil ratio and accelerated catalyst deactivation. To mitigate the impact of increasing feed CCR on re-generator temperature, the heat released during catalyst regeneration must be controlled or

Orthoflow™ FCC

Figure 10: ROSE® Experience

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heat must be removed from the system. The best options for controlling the impact of increas-ing feed CCR are often the use of a catalyst cooler and/or regenerator operation in partial CO combustion mode.

Use of a catalyst cooler offers the advantage of being able to retain the operational simplicity and lower NOx emissions of complete CO combustion but increased regeneration system ca-pacity (air blower, regenerator, flue gas system, etc) may be required to maintain feed rate and conversion with the heavier feedstock. On the other hand, while also addressing the heat balance issue, partial CO combustion minimizes or even eliminates the need for more com-bustion air or regenerator capacity. However, switching from complete CO combustion to par-tial CO combustion requires a CO boiler to control CO emissions and recover valuable heat from CO combustion.

FCC Regenerator Heat Removal

Many of the FCC units built in the early 1940’s included catalyst coolers to remove heat from the regenerator by recirculating dilute phase regenerated catalyst through the tubes of an ex-ternal heat exchanger located beneath the regenerator. However, because of the high quality of the FCC feedstocks at the time, the catalyst coolers proved unnecessary, and this was for-tuitous because the coolers also proved unreliable due to the problem of tube erosion by high velocity catalyst.

With the economic incentive increasing for residue cracking in the FCC unit, regenerator heat removal systems are again in demand. While regenerator bed coils have been successful, these systems lack flexibility to minimize heat removal when occasionally processing higher quality feedstocks. Even with modern materials, di-lute phase catalyst coolers can suffer from erosion problems. Today, external dense phase catalyst coolers have become the norm, but the designs of-fered by the different FCC technology licensors are not the same.

The KBR dense phase catalyst cooler depicted in Figure 11 was commer-cialized in 1991 based on extensive water side KBR experience in high tem-perature ammonia applications and cold flow modeling of the catalyst side at KBR’s Houston Technology Development Center.11 Two distinguishing features of the KBR dense phase cata-lyst coolers impart flexibility in heat removal duty and resistance to tube failure from erosion by the catalyst. The first feature is a gas vent line at the top of the cooler fluid bed that prevents catalyst backmixing between cooler and regenerator whenever the cooler catalyst circulation is stopped, thereby providing complete heat removal turndown capability. Without the vent, cold flow modeling has demonstrated that backmixing between the cooler and regenerator (and

Orthoflow™ FCC

Figure 11: Key Features Of Catalyst Cooler

u High heat transfer coefficient

u Flow-through design, highmean temperature differential

u No fluidization impingementon tubes

u Upflow boiling with naturalboiler feed water circulation

u Tube bundle easily removed

u High turndown capability

u Commercially proven design

Water In

Water /Steam Out

Catalyst In

FluidizationAir

Catalyst Out


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therefore heat transfer in a commercial unit) will occur due to agitation of catalyst in the inlet duct by aeration gas traveling from the cooler back into the regenerator bed. With the vent in place, cooler aeration gas returns to the regenerator through the vent rather than through the catalyst inlet duct, allowing catalyst in the inlet duct to defluidize whenever catalyst circulation is stopped. The other distinguishing feature of the KBR dense phase catalyst cooler design is that tubesheet is located above the tubes, which has several important ramifications:

ü Downward hanging tubes allows the cooler shell fluidiza-tion air to be intro-duced well below the tubes, prevent-ing any possibility of cooler fluidiza-tion air jet im-pingement on the tubes which could cause an erosion related tube failure.

ü Because steam is generated in upflow between the inner and outer tubes, the cooler can utilize natural boiler feedwater circulation, eliminating the need for forced boiler feedwater circulation pumps along with their associated cost and reliability issues.

ü The orientation of the tube bundle also facilitates maintenance and inspection of the cooler because the tube bundle can be pulled from the top of shell.

There are now more than ten KBR dense phase catalyst coolers in operation with four more in design, and there have been no reports of erosion related tube failure in any of these installa-tions. Figure 12 shows that in the recent past, the pace of FCC catalyst cooler installations have been increasing as refiners work to meet the product demand with increasingly heavy feedstocks.

Counter-Current FCC Catalyst Regeneration

KBR has been designing single-stage countercurrent FCC catalyst regenerators for more than 20 years, a process where spent catalyst is introduced evenly across the top of the fluid bed where it travels counter-current to the upflowing gas as depicted in Figure 13. This regenera-tor technology has been proven to perform well in complete CO combustion which is often pre-ferred when processing gas oil FCC feedstocks. The counter-current regeneration technology has also proven effective in partial CO combustion operations by refiners working to mitigate the impact of CCR and vanadium contamination in residue FCC operations.

Nickel and vanadium both deposit quantitatively on the catalyst. Of these, the vanadium is much more troublesome. In the presence of high temperatures and excess oxygen, it is mo-bile and can redistribute over the entire catalyst inventory, contaminating both new and old catalyst. This phenomenon reduces the activity of the unit catalyst inventory because most of

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the catalytic activity is derived from the newest catalyst particles. To mitigate these effects, it is wise to design for partial combustion of CO in the regenerator when processing feedstocks with high vanadium and CCR contents. By restricting vanadium mobility, premature deactiva-tion of the fresh catalyst is prevented and the catalyst equilibrates at a higher activity for a given metals level. Partial CO combustion also helps deal with increasing CCR because more coke can be burned with a given quantity of regenera-tion air often making this a prime consideration in FCC operations limited by regen-erator hardware or the regen-erator air blower.

More recently, countercurrent regeneration technology has also been embraced as a means of minimizing NOx emissions with the regenera-tor flue gas.12 The carbon-rich environment at the top of the fluid bed promotes the reduc-tion of NOx leaving the bed to nitrogen according to the fol-lowing reaction mechanism shown in Figure 14: 2C + 2NO à 2CO + N2

Compared to other types of regenerators, the KBR Low NOx regeneration system operating in complete CO combustion produces 60-80% less NOx in the flue gas. In addition to implemen-

tation in many in KBR-designed Orthoflow™ FCC units, this technology has been success-fully retrofitted into about a dozen existing FCC units of many different types and it has consistently reduced NOx emis-sions. When used in conjunction with a catalyst cooler, complete CO combustion with countercur-rent regeneration is a very vi-able residue FCC processing option, especially with higher quality, lower vanadium feed-stocks.

Orthoflow™ FCC

Air

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Regen cat

Flue gas

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NO

CO

Nitrogen

2 CO + Nitrogen2 C + 2 NO

Figure 14: Lo-NOx Counter-Current RegenerationNOx Reduction Mechanism

Figure 13 Spent Catalyst and Air Distributors

for Countercurrent Regeneration


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Conclusions

The increasing demand for refined petroleum products, increasing reliance on heavy crude oils and the ever-present competition for refinery investment funds have led to a resurgence of investment in solvent deasphalting units as well as projects to install FCC regenerator heat removal systems.

Solvent deasphalting is particularly adept at extracting good quality FCC feed from petroleum residue because the more aromatic molecules in the residue and most of the metals and car-bon residue are rejected with the asphaltene product while the more saturated, less contami-nated components are concentrated in the DAO oil for cracking in the FCC unit. At the same time, ROSE units are relatively inexpensive, easy to operate, and they don’t consume hydro-gen or catalyst.

Supercritical separation of solvent from DAO in the ROSE solvent deasphalting process greatly reduces utility consumption relative to conventional solvent deasphalting processes. ROSEMAX internals in the DAO and asphaltene separators minimize the size and investment cost of the ROSE unit for a given processing capacity.

When processing crude oils having moderate to high levels of contaminant metals and carbon residue, pilot plant data have shown that a combination of ROSE and FCC can be used to convert a higher proportion of the bottom of the barrel into more valuable products com-pared to a combination of vacuum distillation with the processing of a limited volume of highly contaminated atmospheric residue in the FCC unit.

Increasing utilization of asphaltenes from ROSE unit operations as feed to delayed cokers as well as new outlets such as feedstock for gasification units and pelletization for shipment as a solid fuel have accelerated the installation of new ROSE units over the past several years. The unique arrangement of KBR’s dense phase catalyst cooler provides advantages in catalyst cooler reliability and turndown flexibility, and counter-current regeneration enables the refiner to alternate between complete CO combustion and partial CO combustion as needed to ac-commodate changing feedstocks and changing operating objectives. Together or separately, these technologies can provide refiners with the ability to economically produce more refined products from an increasingly heavy supply of crude oil

References 1. Berkmen, P., Sam Ouliaris, Hossein Samiel, “The Structure of the Oil Market and Causes of High Prices”,

International Monetary Fund, 21 September 2005.

2. Baker & O’Brien Inc., “Status of the U.S. Refining Industry”, Presentation to the Association of Industry Pe-troleum Negotiators, October 2005.

3. ENI Group, “World Oil & Gas Review:2005”.

4. Johnson, P.H., K.L. Mills and B.C. Benedict, “Recovery of Catalytic Cracking Stock by Solvent Fractiona-tion”, Industrial and Engineering Chemistry, Vol.47 No.8, August 1955.

5. Gearhart, J., Leo Garwin, “ROSE Process Improves Resid Feed”, Hydrocarbon Processing, May 1976.

6. A.D. Reichle, “Fluid catalytic cracking hits 50 year mark on the run”, Oil & Gas Journal Special, May 18, 1992.

7. Finneran, J.A., J.R. Murphy and E.L. Whittington, “Heavy oil cracking boosts distillates”, Oil & Gas Journal, January 14, 1974.


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8. Northup, A.H., H.D. Sloan, “Advances in Solvent Deasphalting Technology”, NPRA 1996 Annual Meeting, San Antonio, Texas, paper AM-96-55.

9. Lucchese, A., A.H. Northup, Neil A. Sandford, “Improved Mass Transfer Technology for Lube Extraction Processes”, AIChE Annual Meeting, Austin, Texas, November 7-12, 2004.

10. The 2003 NPRA Technology Q&A Session (Question 98), New Orleans, Louisiana, Oct 7 - 10, 2003.

11. Johnson, T.E., “Improve Regenerator Heat Removal”, Hydrocarbon Processing, November 1991.

12. Miller, R., E. Gbordzoe and Y. Yang, “Solutions for Reducing NOx and Particulates from FCC Regenera-tors”, NPRA Annual Meeting, San Antonio, Texas, March 21 – 23, 2004, paper AM-04-23.


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APPENDIX

PILOT PLANT EQUIPMENT

Distillation Pilot Plant

A schematic diagram of the fractionation system used to distill the ANS ATB is shown in Fig-ure 15. The fractionation unit consists of a feed system, preheater, and fractionator tower.

The feed system comprises a feed tank and a duplex piston feed pump. The feed tank is on a scale and is electrically heated. All of the associated piping from the pump to the preheater is also electrically heated.

The feed preheater (L-11) consists of a coil immersed in a lead bath. The bath is divided into four sections, each supplied with an independent temperature controller.

Preheater effluent and steam flow to the 8-inch internal diameter by 19-foot high fractionator tower, entering the flash zone located near the bottom of the tower. The fractionator flash zone

is a 21-inch high section of the tower, containing four pairs of disc and donut baffles. Below this is a 4-inch diameter section which serves as a bottoms re-ceiver and steam stripper.

Above the flash zone, the frac-tionator is equipped with four packed sections, each having internal cooling coils to provide separately-controlled reflux and a liquid draw-off. The top and bot-tom packed sections consist of type 316 stainless steel Goodloe mesh packing and the two middle sections are of type 304 stainless steel Intalox packing. Each of the three upper draw-offs drain into separate steam strippers. The tower overhead is partially con-densed against cooling water. Non-condensables from the over-head drum pass through the frac-tionator back pressure control valve and wet test meter to flare.

PRC

ToCW Gas

MeterF-1

OILC-5

TRC WATER

E-3

TRC

E-2 STEAM

TRC

E-4 STEAM

TRC

STEAM

STEAM

FEED

STEAM

E-1 BOTTOMSPREHEATER

Figure 15 Distillation Pilot Plant


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ROSE Pilot Plant

A schematic diagram of the ROSE pilot plant is shown in the Figure 16. The ROSE Pilot Plant is designed and operated to simulate commercial ROSE unit operation. Having a nominal capacity of one barrel per day, this pilot plant is used to support existing commercial ROSE units, to evaluate the effects of operating parameters on a variety of heavy petroleum feed-stocks, and to produce deasphalted oil, resin and/or asphalt samples for additional process studies and inspections.

The unique design of the ROSE pilot plant includes three product-separation stages--Asphaltene Separator, Resin Separator, and DAO Separator-- to produce three products--asphaltenes, resins, and DAO, respectively. For this program the unit was operated with two stages to produce two products, asphaltenes and DAO. The asphaltene separator can run in either of two extraction modes, countercurrent or mixer/settler. Countercurrent extraction gives a higher DAO yield and a better quality DAO, which is the mode of operation followed for this study.

The ROSE pilot plant simulates commercial operations by combining the feedstock with a specified volumetric solvent-to-oil ratio at elevated pressure and temperature. At these condi-tions, a portion of the feedstock is insoluble in the solvent and is rejected as an asphaltene product.

If a resin product is desired, the dissolved resins and oil and the extraction solvent containing them are heated to a point where the resins are no longer soluble in the solution and may be recovered in the second stage or the Resin Separator. If only two products are desired, the resins can be rejected with the asphaltenes or recovered with the DAO.

In turn, the DAO is recovered in the DAO Separator by increasing the DAO/solvent tempera-ture to the point above the solvent critical temperature. At this point, the DAO is virtually in-soluble in the remaining solvent. The recovered solvent from the overhead of the DAO Sepa-rator is recycled to the Asphaltene Separator after cooling to the desired operating tempera-ture of the Asphaltene Separator.

Figure 16

ROSE Pilot Plant

DAO

Separator

DAOResinsAsphaltenes

Solvent

AsphalteneSeparator

ResinSeparator

Feed +Solvent

Recycled SolventTo SolventTank


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FCC Pilot Plant

The pilot plant used in this work (see Figure 17) is a nominal 1/3 barrel per day Riser FCC unit consisting of cracking, stripping, and regeneration sections, all operating under pressure and with catalyst continuously circulating between these sections.

Oil feed is introduced into the unit from a feed tank by a gear pump, passing through a mass-flow meter to record the feed rate. After mixing with dispersion nitrogen it passes through an electrically-heated preheater. The combined stream is then atomized through a single-tube injector with a 0.025 - 0.035-inch diameter orifice into the flowing catalyst stream in a ½-inch SCH 40 injection chamber, designed for use with heavy feeds to avoid coke deposition on the riser walls. The riser is a 1/4" SCH 40 stainless steel pipe, about 80 feet in length, with provi-sions for temperature and pressure measurements at several points along its length. This de-sign provides the flexibility to simulate adiabatic operation or to run isothermally. All runs in this program were made in the isothermal mode.

Regenerated catalyst passes through a slide valve which controls the catalyst circulation rate, and is transported via a short transfer line to the bottom of the riser with a flow of nitrogen. The dispersed feed stream and the catalyst stream mix in the injection chamber and are trans-ported up the riser.

Riser effluent enters the stripper tangentially. Here the solids are disengaged from the product oil vapors. The solids are then stripped with additional nitrogen to remove interstitial and ad-sorbed hydrocarbons from the solids. The solids then flow to the regenerator where coke is burned off. Upon leaving the unit, the regenerator flue gas is cooled to about 50oF to con-dense water of combustion. The remaining gas is then measured, analyzed, and vented. It is from these flue gas measurements that coke make is calculated.

From the disengager/stripper, the product oil vapors are partially condensed in three stages of cooling. The liquid products are withdrawn periodically and combined. The liquid oil is then fractionated in the TBP still to obtain the fractions of gasoline and heavier products.

The uncondensed product gas exiting the low temperature receiver is analyzed by an on-line G.C., measured by a wet test meter, and then vented to a flare. Other on-line analytical instru-ments monitor the product gas density and the carbon dioxide and oxygen content of the re-generator flue gas.

Economic Extraction of FCC feedstock from Residual Oils

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Figure 17 FCC Pilot Plant

Documents

KBR-Economic Extraction of FCC Feedstock From Residual Oils