strategies for maximizing fcc light cycle...

© 2014 W. R. Grace & Co.

Strategies for Maximizing FCC Light Cycle Oil

Ann Benoit, Technical Service Representative

Refcomm, March 4-8, 2015

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© 2014 W. R. Grace & Co. 2

806040200

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0806040200

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22

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18

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12

10

Bottoms wt%

Conversion wt%

LCO wt% Hi Z/M

Low Z/M

LCO and Bottoms Selectivity

Low Z/M catalyst produces more LCO

© 2014 W. R. Grace & Co. 3

Click to edit text styles

Operating Strategies

Catalyst Optimization

Recycle



Recycle


© 2014 W. R. Grace & Co. 4

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Diesel Maximization: Operating Strategies

Main Fractionator Adjustments

• Reduce gasoline endpoint• Main tower top temperature limitations

• Higher LCO endpoint• Diesel Hydrotreating constraints

• FCC Main Column bottoms temperature limits

• Slurry circuit coking and slurry exchanger fouling

Feedstock

• Removal of diesel range material from the FCC feedstock

Operating Conditions

• Lower reactor temperature

• Higher feed temperatureAdditional bottomsLower volume swell

© 2014 W. R. Grace & Co. 5





Recycle

© 2014 W. R. Grace & Co. 6

Recycle Considerations

To fully maximize LCO, recycle may be required to maintain bottoms yield as conversion is reduced

• Which recycle stream is best to recycle?

• Does the feedstock type play a role?

• Heavy cycle oil or bottoms?

• Which specific boiling range is optimal?

© 2014 W. R. Grace & Co. 7

Lab Simulation of Recycle Operation

A two-pass DCR™ pilot plant+ ACE scheme was adopted to simulate the recycling operation in a commercial unit

• DCR® was used to generate 650+ °F material over a conversion range of 75 to 54 wt% with a resid and VGO feedstock

• 650+ °F stream was distilled into desired bottom cuts

• Bottoms cuts were blended with original resid feed

• ACE testing used original feeds together with recycle streams

• Grace’s MIDAS® premium bottoms cracking catalyst was used

FCC Products

650+FResid and VGO

Feedstock

DC

R

AC

EBlending

Dis

tillatio

n

© 2014 W. R. Grace & Co. 8


DCR™ Pilot Plant Used to Generate Recycle Streams

Recycle streams at 54% conversion distilled to:

• 650 – 750°F

• 650 – 800°F

• 650°F+

• 750°F+

• 800°F+

• 850°F+

Recycle streams at 54%, 58%, 68%, and 75% conversions distilled to

• 650 – 750°F

Quantity of each recycle stream measured from 1st pass cracking

Properties of each recycle stream determined

© 2014 W. R. Grace & Co. 9


Incremental Yields of 650-750°F Recycle Streams

650-750°F fractions from VGO made about the same LCO and bottoms as fresh VGO

650-750°F fractions from resid made more LCO and LPG, less bottoms than fresh resid

Boiling Range VGO650-750ºF from VGO Resid

650-750ºF from Resid

Dry Gas, wt% 0.7 0.7 1.1 1.2

LPG, wt% 8.4 8.9 8.0 10.1

C5+ Gasoline, wt% 44.0 43.6 40.3 38.2

LCO, wt% 26.0 26.3 24.7 37.0

Bottoms, wt% 19.0 18.7 20.3 8.0

Coke, wt% 1.9 1.8 5.6 5.5

© 2014 W. R. Grace & Co. 10


Cracking Path of Hydrocarbon Molecules

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

Saturates Mono-aromatics Di-aromatics Tri-aromatics Tetra-aromatics

Per

cen

tag

e

650-750F Recycle Stream from VGO

650-750F Recycle Stream from Resid

LCO

+

Di-aromatics

R

R’

Bottoms

+

Tri-aromatics

R’

R

Coke

Tetra-aromatics

+

Mono-aromatics Gasoline

R

R’

R’: hydrocarbons with less than 4 carbon atoms

© 2014 W. R. Grace & Co. 11


Recycle Streams at 54% Conversion from Resid

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15

10

5

16

12

8

4

0

850

F+

800

F+

750F

+

650F

+

650-

850 F

650-

800F

650-

750F

Fres

h Fe

ed

1000

900

800

700

600

850 F+

800 F+

750F

+

650F

+

650-

850

F

650-

800F

650-

750F

Fres

h Fe

ed

12

11

10

9

API Gravity @60 øF

Feed ID

Data

Conradson Carbon, wt.%

50% Vol% F Hydrogen, wt.%

Properties

© 2014 W. R. Grace & Co. 12


650-750ºF Recycle Stream vs. Conversion for Resid

Properties

© 2014 W. R. Grace & Co. 13


55 wt% conversion vs. % recycle in combined feed - Resid

25.8

25.5

25.2

24.9

24.6

20.4

20.1

19.8

19.5

19.2

16%12%8%4%0%

6.00

5.75

5.5016%12%8%4%0%

40.8

40.4

40.0

LCO, wt%

% Recycle in Combined Feed

Bottoms, wt%

Coke, wt% C5+ Gasoline, wt%

650-750F

650-800F

650-850F

650+

750+

Key Yields

© 2014 W. R. Grace & Co. 14


Element Tracking Approach

Element Tracking Approach can be used to simulate a continuous recycle operation

Two-pass cracking can closely simulate steady-state

~0 for Recycle Ratios ~ <= 15%

© 2014 W. R. Grace & Co. 15


Maximum LCO Yields – Fresh Feed Basis – Resid

Max. CokeAllowed

Limited by Max.

Recycle Stream

Limited by Max. Coke

Max

Gasoline

Base

Base No

Recycle 650-750°F 650-800°F 650-850°F 650+°F

Conversion 70.0 55.1 61.2 64.2 65.1 64.7

Recycle Ratio 0 0 0.10 0.14 0.16 0.15

Maximun recycle available 0.10 0.14 0.18 0.24

Hydrogen, wt% 0.11 0.09 0.10 0.11 0.12 0.12

Total C1's & C2's, wt% 1.4 1.0 1.1 1.3 1.4 1.4

Propylene, wt% 3.3 2.1 2.4 2.6 2.7 2.7

Total C3's, wt% 3.9 2.4 2.7 2.9 3.1 3.1

Total C4='s, wt% 5.1 3.9 4.5 4.5 4.7 4.8

Total C4's, wt% 8.5 5.6 6.6 6.6 6.9 7.0

C5+ Gasoline, wt% 49.5 40.5 44.7 46.9 47.0 46.5

RON 89.6 89.2 89.4 89.5 89.5 89.7

MON 78.6 77.3 77.7 77.8 77.7 77.9

LCO, wt% 20.5 24.7 28.9 30.2 29.9 29.3Bottoms 9.5 20.2 9.9 5.6 5.0 6.0

Coke, wt% 6.7 5.6 6.1 6.5 6.7 6.7

© 2014 W. R. Grace & Co. 16


650 – 800/850°F produces the highest LCO selectivity with slight coke penalty

20

15

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48

44

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7570656055

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Bottoms, wt%

Conversion

C5+ Gasoline, wt%

LCO, wt% Coke, wt%

No Recy cle

Recy cle 650-800/850

Recy cle all 650-750F

Product Selectivity with and without Recycle – Resid

Yields on a fresh feed basis

© 2014 W. R. Grace & Co. 17


Fresh Feed & Recycle Cracking Selectivity – Resid

2nd pass cracking of 650-750oF fraction at reduced conversion made more LCO than cracking fresh feed with almost no penalty on coke and gasoline

Large coke debit at increased conversion

10

8

6

4

0

-10

-20

-30

-40

7570656055

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12

8

4

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7570656055

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15

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Max Recycle Ratio

Conversion

C5+ Gasoline, wt%

LCO, wt% Coke, wt%

Yields of 2nd pass cracking (Recycle Cracking) minus Yields of Fresh Feed Cracking

© 2014 W. R. Grace & Co. 19

Catalyst Strategies for Maximum LCO

Maximize Bottoms Cracking to LCO

• Lower Z/M using a high diffusivity matrix

• Optimal matrix surface area, pore size, and pore distribution

Optimal Ecat MAT

• Lower within slurry and liquid yield limits with consideration to economics

• Optimal rare earth for activity and hydrogen transfer

Reduced zeolite surface area

• Minimize LCO conversion via zeolite

Maintain or increase liquid yield by increasing LPG

• ZSM 5 additives

• Lower zeolite rare earth

• Catalyst design to increase C4= selectivity

© 2014 W. R. Grace & Co. 20

Design Concept for ACHIEVE® 400 FCC Catalyst

ACHIEVE® 400 FCC Catalyst delivers higher LCO yield, greater gasoline octane, and improved C4= selectivity through:

• Low Z/M ratio to drive bottoms uplift and decrease hydrogen transfer activity

• Dual zeolite functionality (USY + pentasil) with tailored acidity to

• Boost octane via isomerization activity

• Crack gasoline olefins more selectively to C4= rather than C3=

• Maintenance of excellent coke selectivity using Grace’s proprietary alumina matrix first commercialized in the MIDAS® catalyst family

© 2014 W. R. Grace & Co. 21


Modeling with Optimal Recycle Stream and Catalyst System

Full Burn FCC - Residual Feedstock

• Model yields and operating conditions

• Base Resid Operation – Maximum Gasoline

• Case 1 – Maximum LCO with 650-800°F recycle stream

• Case 2 – Optimized maximum LCO operation

© 2014 W. R. Grace & Co. 22

Base Maximum Gasoline Operation

Product Relative Price

C3=, $/b - 9.0

C4=, $/b +17.0

Gaso., $/b Base

LCO, $/b +21.0

Slurry, $/b -25.0

Resid Feedstock Operation Base

Mode Max Gasoline

Recycle %FF (650 to 800°F) 0.0

Reactor Temperature, °F 975

Air Blower, mscfm Constraint

Wet Gas Compressor, scf/b Constraint

LPG/Gaso., Vol% 23.8/56.9

RON/MON 92.3/80.4

LCO , Vol% FF 22.3

Slurry , Vol% FF 7.0

C3+, Vol% FF 110.0

Incremental $/b Base

© 2014 W. R. Grace & Co. 23

Maximum LCO with ACHIEVE® 400 FCC Catalyst

Volume swell is critical to maintaining profitability

Resid Feedstock Operation Base Case 1 Case 2

MIDAS® FCC Catalyst ACHIEVE® 400 FCC Catalyst

Mode Max Gasoline Max LCO Max LCO

Recycle %FF (650 to 800°F) 0 7 7

Reactor Temperature, °F 975 960 960

Air Blower, mscfm Constraint Constraint Constraint

Wet Gas Compressor, scf/b Constraint ~90%Constraint Constraint

LPG/Gaso., Vol% 23.8/56.9 21.2/54.3 24.8/51.6

C4=, Vol% 8.9 7.7 9.3

RON/MON 92.3/80.4 91.4/80.0 92.4/80.4

LCO , Vol% FF 22.3 27.0 27.0

Slurry , Vol% FF 7.0 6.7 6.7

C3+, Vol% FF 110.0 109.2 110.1

Incremental $/b Base $0.08 $1.16

© 2014 W. R. Grace & Co. 24

Summary

The proper catalyst system, operating conditions and recycle ensure a profitable LCO operation

Maximum FCC LCO operation is challenged by bottoms yield and the need to preserve C3+ liquid yield and octane as conversion is reduced

Shifting operating conditions (lower reactor temperature, higher feed temperature) can be adjusted to increase LCO, but this comes at a price

Recycle can be employed to fully maximize LCO at reduced conversion

• 650 to 800°F recycle stream produces the highest LCO when processed against a coke constraint

© 2014 W. R. Grace & Co. 25

GRACE®, ACHIEVE® and MIDAS® are trademarks, registered in the United States and/or other countries, of W. R. Grace & Co.-Conn. DCR™ is a trademark of W. R. Grace & Co.-Conn. This trademark list has been compiled using available published information as of the publication date of this brochure and may not accurately reflect current trademark ownership or status. GRACE CATALYSTS TECHNOLOGIES is a business segment of W. R. Grace & Co.-Conn. © Copyright 2015 W. R. Grace & Co.-Conn. All rights reserved.

© 2014 W. R. Grace & Co. 26

Ann Benoit | FCC Technical Service Representative

Grace Catalysts Technologies

[email protected]

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