Advances in Chevron RDS technology for heavy oil upgrading flexibility

Fuel Processing Technology, 35 (1993) 39-54

39

Elsevier Science Publishers B.V., Amsterdam

Advances in Chevron RDS technology for heavy oil upgrading flexibility G e o r g i e a n n a L. S c h e u e r m a n * , D a v i d R. J o h n s o n , B r u c e E. Reynolds, R o b e r t W. B a c h t e l and R i c h a r d S. T h r e l k e l

Chevron Research and Technology Company, Richmond, CA (USA) (Received November 12, 1992; accepted December 21, 1992)

Abstract

Over the last 20 years, environmental and market forces have not only increased the demand for residuum hydrotreating technology but have also changed it from a technology which simply desulfurizes to one which provides maximum conversion. Simultaneously greater feed flexibility was also being demanded. Chevron has been active throughout this period developing RDS/VRDS technology and the catalysts that go with that technology. Currently, Chevron provides a whole range of RDS catalysts from HDM catalysts which can handle heavy, high metals feeds to active residuum HDN catalysts which can produce RFCC feed. In addition, Chevron has developed a new technology called Onstream Catalyst Replacement (OCR) which allows refiners to handle very high metals feeds without shutting down their residuum hydrotreater for catalyst changeouts. These continuing developments put Chevron in a unique position to provide a wide range of residuum hydrotreating technology and catalysts for the coming decade and beyond.

1 INTRODUCTION F o r well o v e r 20 y e a r s r e s i d u u m h y d r o t r e a t i n g has been used to meet i n c r e a s i n g l y s t r i n g e n t e n v i r o n m e n t a l r e q u i r e m e n t s as c r u d e oil q u a l i t y h a s d e t e r i o r a t e d . I n r e c e n t years, p r o d u c t d e m a n d s h a v e shifted from fuel oil to l i g h t e r products. This h a s c a u s e d m a n y refiners to c h a n g e t h e i r view of r e s i d u u m h y d r o t r e a t i n g t e c h n o l o g y from one w h i c h simply desulfurizes to one w h i c h provides m a x i m u m c o n v e r s i o n of r e s i d u u m to t r a n s p o r t a t i o n fuels. W h i l e e a r l y r e s i d u u m h y d r o t r e a t e r s were designed to r e m o v e sulfur, more r e c e n t u n i t s are being designed to i n c r e a s e r e s i d u u m c o n v e r s i o n a n d provide feed for d o w n s t r e a m c o n v e r s i o n units, t h u s r e d u c i n g or c o m p l e t e l y e l i m i n a t i n g fuel oil p r o d u c t i o n . This m u s t be a c c o m p l i s h e d while feeding m o r e and more difficult feeds (e.g. v a c u u m as well as a t m o s p h e r i c r e s i d u a w i t h i n c r e a s e d sulfur, metals, a n d M i c r o c a r b o n Residue [MCR] content). P u t simply, t o d a y ' s r e s i d u u m h y d r o t r e a t e r m u s t provide m a x i m u m c o n v e r s i o n w i t h m a x i m u m feed flexibility.

*Correspondence should be addressed to: Jordan S. Lasher, Chevron International Oil Company, Inc., 555 Market Street, San Francisco, CA 94120 - 7146.

40

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39-54

1500 1400 I 1300 1200 1100 Q ¢/) eL 1000 m 900 •~ ,',

(J

800 700 600 50O 400 300 200 lO0 0

1965

1970

1975 1980 Year

1985

1990

Fig. 1. Resid hydrotreating units licensed world-wide. These environmental and market forces have not only changed the nature of residuum hydrotreating technology but have also increased the demand for it. Figure 1 shows the resid hydrotreating units licensed world-wide. Residuum hydrotreating capacity has risen steadily since 1965 and our projections show continued growth. Throughout this time, Chevron (either as Chevron or as Gulf before the 1985 Chevron-Gulf merger) has been a significant player in the residuum hydrotreating arena. This is illustrated in Fig. 2 which shows fixed bed residuum hydroprocessing capacity by licensor. As the licensor of 44.7% of the total capacity, Chevron is one of the predominant licensors of fixed-bed hydroprocessing technology. To remain competitive, Chevron has continued to improve both catalyst and process technology for residuum hydroprocessing. Recent improvements provide for more demetalation (HDM), desulfurization (HDS), MCR removal (MCRR), denitrification (HDN), and cracking conversion (HCR) while simultaneously providing increased feed flexibility. This places Chevron in a unique position to meet the changing demands for increased residuum conversion and maximum feed flexibility expected throughout the 1990's and into the next century.

2 CATALYST DEVELOPMENTS To meet the demands for more residuum conversion, refiners have turned to a variety of processing schemes which utilize fixed-bed RDS (atmospheric

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39 54

41

Capacity, MBPSD (Total = 1210)

Shell (3.7%)

.8%) OP (10.0%) Chevron (44.7%)

-.al (33.7%) Fig. 2. Fixed bed residuum hydroprocessing capacity units now operating on residuum

VGO~ VR

>

I RDS/ VRDS

Naphtha and Diesel Product

RDS/VRDS

Gas Oil

Oblectiv~

SDA Oil

HCR & HDN(HDS)

R( ;id

_•

Vacuum I Column J

I

I Resid

,] •

<50 ppm Ni + V, <10%MCR ~ I

Coker

I

Fuel Oil Product

Resid FCC

MCRR & HDS

HDS & HCR

I

HDM,MCRR & HDN (HDS)

Fig. 3. Resid conversion alternatives.

residuum hydrotreating) or VRDS (vacuum residuum hydrotreating). No one process suits all applications, "so refiners must select the best processing combination for their particular situation. Figure 3 illustrates several of these processing alternatives. Each requires different RDS/VRDS processing objectives and thus a different catalyst system to meet those objectives. Table 1 shows that these RDS catalyst systems must provide a combination of catalytic activities from HDM to HDN and HCR. This can be accomplished by a layered

42

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39 54

TABLE 1 Chevron RDS/VRDS hydrotreating Chevron catalysts VR/VGO + H2

High quality liquids

Impurity removal: Hydrocarbon upgrading:

Sulfur Nitrogen Ni/V Cracking Visbreaking MCR Reduction

End use

RDS/VRDS Objectives

Fuel oil production Coker feed VGO FCC feed Resid FCC feed

HDS and HCR HDS and MCRR HCR and HDN (HDS) HDM, MCRR, and HDN (HDS)

Layered catalyst systems

HDM HDM/HDS HDS/HDN/HCR

HDS HDN HDM HCR HVB MCRR

catalyst system which utilizes several catalysts designed for specific processing objectives. Figure 4 shows the general philosophy used in designing a catalyst system for both feed flexibility and maximum residuum conversion. Catalyst grading is used to provide the right activity and selectivity at each part of the reactor system. At the top of the reactor, trash, salt, and metals removal are the primary objectives. This is accomplished by size, shape, and activity grading to meet the needs of the particular residuum feed and to protect the higher activity conversion catalysts further downstream. The conversion catalysts are chosen to meet the specific processing objectives. For example, this could include catalysts for MCRR, HDM, and HDN to prepare RFCC feed or catalysts for MCRR, HDS, and HDN to prepare coker feed. Chevron has been active for many years developing catalysts to meet all of these needs. Table 2 lists Chevron (ICR) and premerger Gulf (GC) catalysts developed for residuum hydroprocessing. This list includes catalysts which fit the whole spectrum of resid hydroprocessing needs from HDM for nickel (Ni), vanadium (V), iron (Fe), sodium (Na), and calcium (Ca) removal, all the way to high activity resid HDN catalysts. For feed flexibility, Chevron has developed a number of catalysts and grading systems which can not only remove Ni and V, but are also designed to remove high reactivity metals such as Fe, Ca, or Na. In addition to rapidly poisoning catalysts, these metals can also cause rapid pressure drop buildup.

43

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39-54 Inlet Function

Catalyst Properties

• Trash and Salt Removal

• Inert • Size and S h a p e Grading

• Metals R e m o v a l (Ni, V, O r g a n i c Fe, Ca, Na)

• Larger Pores • Less Catalyst Metals • Size, Shape, and Activity Grading

Reactor • Sulfur R e m o v a l • • • •

Deep Desulfurization MCR Conversion Cracking C o n v e r s i o n Nitrogen R e m o v a l

• Smaller Pores • Higher Surface Area • M o r e Catalyst Metals

Outlet

Fig. 4. Residuum hydroprocessing catalyst system design

TABLE 2 Chevron RDS/VRDS catalysts Year developed

HDM

1969 1970 1974 1975 1979 1981 1982 1983 1984 1985 1987 1988 1990 1991

HDS

HDN

GC-101 ICR-105 GC-100 GC-102 GC-105, 106, 107

ICR107 ICR114

ICR 121 ICR 122 (A, B, C,D, E, F,G) ICR 125 GC-125, 130 GC-102, 107, (L, M, S) ICR-131 ICR 132 ICR 133, ICR122H ICR 138

ICR 130

ICR 135, GC-112, 117 ICR 137

F i g u r e 5 s h o w s t h a t I C R 122 T y p e II is quite effective for r e m o v i n g i r o n f r o m d e a s p h a l t e d oil (DAO). U t i l i z i n g this c a t a l y s t a l o n g w i t h o t h e r C h e v r o n c a t a l y s t s , this h y d r o c r a c k e r was able to i n c r e a s e r u n l e n g t h by 50%. F i g u r e 6 s h o w s t h a t a n e v e n n e w e r c a t a l y s t is m o r e effective t h a n I C R 122 T y p e II for Ca r e m o v a l . E f f e c t i v e r e m o v a l of t h e s e p r o b l e m m e t a l s (Fe, Ca, a n d Na) c a n g r e a t l y i n c r e a s e a r e f i n e r ' s o p t i o n s for r e s i d u u m h y d r o t r e a t e r feeds.

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39 54

44 3-

I

.._= ¢:

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Relative I n t e g r a t e d Iron C o n c e n t r a t i o n s m - -

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T y p e II T y p e III

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I

I

I

I

I

0.6

0.5

0.4

0.3

0.2

0.1

t

Center

Fractional Radius from Catalyst Center

Fig. 5. Iron profiles on spent ICR 122 catalysts from Chevron's Richmond DAO Hydrocracker.

5.0 4.5 4.0 o<

3.5 3.0

o rq) 0 r" 0

o (J

2.5 2.0 1.5 1.0

atalyst

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0.6

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Fig. 6. New Catalyst with improved calcium penetration

0.2

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45

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39-54

TABLE 3 Chevron demetalation catalysts (tests with Maya 650°F ÷ b.p. fraction) Removal at 713 °F %

Sulfur MCR Vanadium

ICR 122LSC

ICR 121

GC-130

ICR 132

34 21 64

57 3O 68

60 29 66

53 27 72

Removal at 755 °F %

Sulfur MCR Vanadium Vanadium distribution factor

ICR 122LSC

ICR 121

GC-130

ICR 132

58 38 78

76 45 76

79 48 75

71 42 84

0.48

0.36

0.39

0.55

Fortunately, for many high metals feeds, removal of Fe, Ca, and Na is not a major concern. Instead, high activity for Ni and V removal is of major importance, along with good capacity for these metals. Table 3 shows t hat ICR 132 is an improvement over earlier Chevron and Gulf HDM catalysts for both V removal and capacity. [Higher vanadium distribution factors indicate higher metals capacity.] The combination of the ICR 122 series catalysts with ICR 132 makes an effective HDM system for heavy, high metals-containing feeds. As mentioned earlier, today's residuum hydroprocessing unit must not only remove metals but also provide HDS, HDN, and MCRR activity to make acceptable feeds for processing units downstream. Table 2 shows t h a t Chevron has also been active in this area of RDS catalyst development. Most recently, two new conversion catalysts have been developed. ICR 137 was developed for increased metals tolerance while maintaining most of ICR 131's excellent HDS and MCRR activity. ICR 135 was developed to improve upon the HDS, MCRR, and HDN activity of ICR 131. Figures 7 and 8 show the HDS and MCRR activities of ICR 137 and ICR 135 relative to ICR 131. While these figures show t h a t ICR 137 does sacrifice some HDS and MCRR activity, Fig. 9 shows t hat ICR 137 provides significantly increased run life because of its increased metals tolerance. In applications where more HDS and HDN activity are required, ICR 135 is an attractive choice. Table 4 shows product qualities for two catalyst systems, one containing ICR 131, the other ICR 135. Clearly ICR 135 provides products containing less sulfur and nitrogen. Some applications require even more catalyst activity, especially HDN activity. In these cases, ICR 130 is an attractive option. It was developed to

46

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39-54 70

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25

135

15 10 I

0

I

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50 100 150 200 250300350400450500 Run Hours

I

I

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f

550600650 700750 800850

Fig. 7. HDS Activity for ICR conversion catalysts (Arabian Heavy AR).

50

i

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• 55% Target I I MCR Conversion J ~

55 50

~"

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0 50 100 150 200 250300350 400450500 550600 650700750 800 850

Run Hours Fig. 8. MCR Conversion activity for ICR catalysts (Arabian Heavy AR).

provide H D N activity equal to or b e t t e r t h a n previous C h e v r o n H D N c a t a l y s t s such as ICR 107 or 114 but at a lower m a n u f a c t u r i n g cost. Table 5 shows t h a t ICR 130 produces distillate cuts with significantly lower n i t r o g e n levels t h a n earlier C h e v r o n catalysts.

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39-54

47

TABLE 4 Product qualities--ICR 131 versus ICR 135 (ICR 121/131/131 versus ICR 121/135/135 Arab Heavy 650°F +) Fraction

ICR 131

350-650 °F 650-1000 °F 1000 °F +

ICR135

Nitrogen

Sulfur

Nitrogen

Sulfur

339 ppm 1041 ppm 0.34 wt%

373 ppm 0.34 wt% 1.03 wt%

148 ppm 819 ppm 0.39 wt%

100 ppm 0.12 wt% 0.96 wt%

loo[ 8O

'°t

~.

ICR 132/131/131

70

"ff E

e~

50

~Na 40 !~ o

~

ICR 132/137/137

3o

20' 101 0

1

0

I

I

1

2 3 4 Relative Throughput

I

I

I

5

6

Fig. 9. Normalized temperature for MCR removal (55% conversion target in whole liquid product). TABLE 5 Chevron RDS hydrotreating pilot plant data with Chevron HDN catalyst ICR 130. Feed: Partially demetallized California atmospheric residuum (7100 ppm N, 105 ppm Ni + V) Parameter

Catalyst GC-100

Conversion, % (whole liquid product) Sulfur Nitrogen Nitrogen level in distillation cuts, ppm 500-600 °F 650-800 °F 800-980 °F

ICR 114

ICR 130

82 23

83 30

79 56

2000 3000 4100

1600 3000 4000

460 1300 2200

48

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39-54

3 RDS CATALYST UTILIZATION T h r o u g h j u d i c i o u s s e l e c t i o n of RDS c a t a l y s t s , a wide v a r i e t y of RDS processing o b j e c t i v e s c a n be satisfied. F o r example, T a b l e 6 i l l u s t r a t e s C h e v r o n V R D S c a p a b i l i t i e s to p r o d u c e R F C C feed f r o m a v a c u u m r e s i d u u m feed. U s i n g a n a p p r o p r i a t e l y designed c a t a l y s t system, a v a c u u m r e s i d u u m feed c o n t a i n i n g h i g h levels of MCR, sulfur, a n d m e t a l s was p r o c e s s e d to p r o d u c e a VRDS p r o d u c t w h i c h is quite a c c e p t a b l e for R F C C p r o c e s s i n g (low metals, signific a n t l y r e d u c e d MCR, sulfur, a n d nitrogen; w i t h i m p r o v e d API). If e x t r a low sulfur fuel oil is required, a different c a t a l y s t s y s t e m c a n be utilized. T a b l e 7 i l l u s t r a t e s the use of a GC-101, GC-100 s y s t e m to p r o d u c e low sulfur fuel oil f r o m A r a b i a n L i g h t residuum. This c a t a l y s t s y s t e m provides the m e t a l s t o l e r a n c e r e q u i r e d by the A r a b i a n feed and the deep d e s u l f u r i z a t i o n a c t i v i t y w h i c h is the k e y o b j e c t i v e in this a p p l i c a t i o n .

TABLE 6 Chevron VRDS pilot plant performance Performance

VRDS Feed ~

VRDS Product

Boiling range, °F Gravity, °API CCR b, wt% Sulfur, wt°~ Nitrogen, wt% Nickel + vanadium, ppm Viscosity, cSt at 212 °F

1000 + 4.6 23.1 5.3 0.42 195 5500

650 + 18.1 5.7 0.24 0.15 3 32

1000 °F+ Conversion, LV % 650°F+Yield, LV % H 2 Consumption, SCFB

54.2 18.4 1650

aArabian Heavy/Kuwait 50/50 (v/v). bCCR Conradson carbon.

TABLE 7 Extra low sulfur fuel oil production (Catalyst system: GC-101, GC-100 middle-of-run) Parameter

Feed

Crude source Gravity, ~API Sulfur, wt% Conradson carbon, w t ~ Nitrogen, ppm Nickel, ppm Vanadium, ppm Viscosity, cSt at 212 °F

Arabian Light 18.5 2.93 5.7 1600 13 2.5

650°F ÷ Product 25 0.12 2.3 900 0.5 0.3 14

49

G.L. Scheuerman / Fuel Processing Technol. 35 (1993) 39 54

TABLE 8 Pascagoula residuum conversion project: Chevron RDS hydrotreater feed flexibility Design feedstock Arabian Heavy Composition, % 760--1000°F VGO 1000°F + Residuum 68~900 °F HCGO Inspections Gravity, °API Sulfur, wt% Nitrogen, ppmw Ramsbottom Carbon, wt% Viscosity, cSt at 210 °F Ni + V, ppmw

Operation range various crudes

50 50 0

30-80 20-70 0-25

11.8 4.4 2850 14 105 130

9-20 2.5 5.0 2000-3500 8-18 30-227 20-400

In addition to tailoring catalyst systems to meet specific product requirements, Chevron has also used its wide selection of RDS catalysts to provide its Pascagoula Residuum Conversion Pl ant with extensive feed flexibility. Table 8 compares the range of feeds actually run at the Pascagoula RDS with its original design feedstock. Continuous improvements in Chevron RDS catalysts and knowledge of how to utilize these catalysts, has allowed the Pascagoula RDS to process increasingly more difficult feeds while meeting or exceeding design conversion targets. These are only a few examples of how Chevron catalysts can be used to meet the dual requirements of feed flexibility and maximum residuum conversion. In each case, the feed properties, processing objectives, and processing constraints such as space velocity, temperature, and hydrogen partial pressure must be taken into a c c ount when selecting the appropriate catalysts. By using a layered catalyst system containing 2 to 10 catalysts, an optimum system can be designed for a wide range of feeds and processing objectives.

4 PROCESS DEVELOPMENTS Even the best fixed-bed catalyst system cannot deal with every residuum feed th at is available. Figure 10 shows what happens to fixed-bed catalyst life as feed metals increase. At some point the fixed-bed run length becomes too short to be practical. Unfortunately, these high metals feeds which make fixed-bed RDS units impractical are often the most economically attractive feeds because of their relatively lower price. This provides a substantial economic incentive for finding other ways to process these cheaper, heavier feeds. In response to this incentive, Chevron has developed a new RDS technology called Onstream Catalyst Replacement (OCR) which provides increased flexibility to process heavier, higher metals feedstocks. OCR efficiently removes the

G.L. Scheuerman/ Fuel Processing Technol. 35 (1993) 39-54

50

1.0 - •

0.8 -

•

Kern

• 10% Maya + 90% AH

.-I

>,

Arabian Heavy (AH)

0.6

• Isthmus >

0.4

n-

•

Maya

0.2 Boscan • 0 0

I 200

I 400

I 600

I 800

I 1000

I I I 1200 1400 1600

I I 1800 2000

Feed Metals, ppm

Fig. 10. Relative catalyst life versus feed metals. feed metals while allowing the refiner to continue operation. Figure 11 shows a schematic of the OCR reactor system. Feed flows up through the OCR reactor bed. The reactor contains internals which allow removal of spent catalyst from the bottom and addition of fresh catalyst to the top while maintaining plug flow of the catalyst, and good distribution of liquid, gas, and hydrogen quench. Additional high and low pressure vessels are required to safely handle the fresh and spent catalyst. Since feed is moving upflow while the catalyst is moving down through the reactor, countercurrent contacting of catalyst and feed is accomplished. This countercurrent contacting allows the removal of only the most spent catalyst, thus providing extremely efficient catalyst use. Spent catalyst can contain as much as twice the Ni + V content of the overall reactor average. One way to utilize the OCR reactor is to make it a guard reactor in front of a conventional fixed-bed RDS reactor system. Figure 12 illustrates this particular application. The OCR reactor is used in place of a fixed-bed HDM guard reactor. In such an application the OCR reactor can handle high metalscontaining feeds while protecting the downstream HDS catalysts. Since the OCR reactor does not have to be shut down to remove spent catalyst, it can provide continuous protection for the downstream conversion catalysts, extending their run life. Figure 13 illustrates the advantage of an OCR (countercurrent system) relative to fixed-bed or cocurrent systems. Substantial catalyst savings can be realized as increasingly more difficult feeds (higher metals) are processed. OCR reactors not only provide catalyst consumption savings but can also save on reactor size, reducing capital costs for high pressure reactors. Figure 14 shows

51

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39-54 Fresh Catalyst Bin

I

Catalyst Feed Vessel ~

> Productto

RDSReactor

High Pressure

OCRto r

Catalyst Vessel

_ I I Low I~ressure

~ L

~

Feed In

CatalystVessel

J

Spent CatalystBin

Fig. 11. OCR Reactor system.

Conventional RDS

II II I1 II 1 OCR + RDS

-.,-I><

Fig. 12. Use of OCR in RDS hydrotreating. t h e s a v i n g s in r e a c t o r size for a n O C R r e a c t o r o v e r a c o n v e n t i o n a l fixed-bed HDM reactor. T h e a b i l i t y to r e m o v e feed m e t a l s w h i l e c o n t i n u i n g o p e r a t i o n allows a variety of c o m m e r c i a l a p p l i c a t i o n s for O C R t e c h n o l o g y . T a b l e 9 lists s o m e of t h e s e a p p l i c a t i o n s . F o r n e w r e s i d u u m h y d r o p r o c e s s i n g units, O C R t e c h n o l o g y

52

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39-54 8 Cocurrent Moving Bed Plus Fixed Bed

Relative Catalyst, Consumption/ 4 Vol of F e e d

Fixed Bed Alone

2-

J ~ . J

0

0

I

I

I

100

200

300

Countercurrent Moving Bed Plus Fixed Bed I

I

I

400

500

600

Feed Metals, ppm Ni + V

Fig. 13. Comparison of catalyst consumption.

==E all:

3 2

m

-6.E n"

00

I 100

I 200

300

Feed Metals Ni + V, ppm

Fig. 14. Savings in reactor size with OCR. provides increased feed flexibility, longer c a t a l y s t life for d o w n s t r e a m fixedbed catalyst, reduced c a t a l y s t consumption, and r e d u c e d i n v e s t m e n t because of savings in r e a c t o r size and r e d u c e d d o w n t i m e for fixed-bed c a t a l y s t changeouts. F o r existing units, an OCR retrofit can also be an a t t r a c t i v e option. E i t h e r a new OCR r e a c t o r can be added in f r o n t of an existing fixed-bed RDS or an existing fixed-bed r e a c t o r can be c o n v e r t e d into an OCR reactor. Tables 10 and 11 i l l u s t r a t e the economics for an OCR retrofit of an existing fixed-bed RDS feeding A r a b i a n L i g h t residue with a one-year cycle. T h e OCR retrofit allows a feed c h a n g e to a 50/50 mix of A r a b i a n L i g h t and A r a b i a n H e a v y residua while going to a two-year cycle. A p a y o u t of less t h a n two years makes this retrofit a v e r y a t t r a c t i v e investment.

53

G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39-54 TABLE 9 Commercial applications of OCR technology • New residuum hydroprocessing units: Added feed flexibility (lower cost crude) Longer catalyst lives Reduced catalyst consumption Reduced investment • Existing residuum hydroprocessing units: Retrofit at reasonable cost

TABLE 10 Conceptual study OCR retrofit to existing 50-MBPOD residuum hydroprocessing unit • Objectives: Change from 100% Arabian Light residuum feed to 50% Arabian Light/50% Arabian Heavy feed Maintain constant RFCC feed quality Increase fixed bed residuum hydrotreating catalyst life from one year to two years -

TABLE 11 Economic summary conceptual study retrofit of existing RDS unit. Savings over base Arabian Light case a

$MM/Yr

Heavier crude b Increased crude c Chemicals + catalyst Products

25 (20) (5) 24 Net

Investment, U.S. Gulf Coast Basis

$24 $40

MM/Yr MM

aConstant RFCC feed quality. bArabian Light - Arabian Heavy crude differential = $3/bbl. CIncreased crude due to increased operating factor from 92 to 96%.

In addition to all of the special mechanical and process aspects of the OCR technology, a new catalyst was also required. This first generation OCR c a t a l y s t ( I C R 138) w a s d e s i g n e d t o m e e t a l l o f t h e s p e c i a l p h y s i c a l r e q u i r e m e n t s of the OCR system and was designed for good HDM activity and metals c a p a c i t y . W h i l e I C R 138 s h o w s g o o d a c t i v i t y f o r m e t a l s , s u l f u r , a n d M C R

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G.L. Scheuerman/Fuel Processing Technol. 35 (1993) 39-54

removal, we are continuing to develop second and third generation OCR catalysts which will significantly improve upon ICR 138. Chevron continues to develop OCR technology and catalysts. The first commercial application of OCR technology is at ldemitsu Kosan Company Ltd.'s Aichi Refinery. In this application an existing two-train RDS hydrotreater is retrofitted with two new OCR reactors. Startup was in May 1992.

5 SUMMARY Today's refiners are facing the challenge of installing residuum hydrotreating processes that provide both feed flexibility and maximum residuum conversion. In many cases, these residuum hydrotreating processes must be integrated into existing refinery processing schemes. Fixed-bed RDS/VRDS technology can meet a wide range of processing objectives using appropriately designed layered catalyst systems. Chevron has been and continues to be active in developing both RDS/VRDS technology and the catalysts for that technology. Chevron RDS catalysts range from HDM catalysts designed to remove Ni, V, Fe, Ca, and Na to HDS catalysts designed to maximize sulfur, MCR, and nitrogen removal. These catalysts provide both feed flexibility and maximum residuum conversion. Recently, Chevron has also developed a new technology, OCR, and a catalyst specifically designed for it. OCR allows even greater feed flexibility by removing spent catalyst and adding fresh catalyst while the RDS reactor remains onstream in normal operation. These advances in RDS catalyst and process technology put Chevron in a strong position to provide state-of-the-art residuum processing technology for the 1990's and beyond.