Strategies for Maximizing FCC Light Cycle Oil

Transcription

1 Paste Logo Here Strategies for Maximizing FCC Light Cycle Oil Ann Benoit, Technical Service Representative Refcomm, March 4-8, 2015

2 LCO and Bottoms Selectivity 90 Bottoms wt% 24 LCO wt% Hi Z/M Low Z/M Conversion wt% Low Z/M catalyst produces more LCO 2

3 Strategies for Maximizing FCC Light Cycle Oil Operating Strategies Recycle Catalyst Optimization Click to edit text styles 3

4 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 temperature Additional bottoms Lower volume swell Click to edit text styles 4

5 Strategies for Maximizing FCC Light Cycle Oil Operating Strategies Recycle Catalyst Optimization Click to edit text styles 5

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? 6

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 Resid and VGO Feedstock DCR 650+F Distillation Blending ACE FCC Products 7

8 DCR Pilot Plant Used to Generate Recycle Streams Recycle streams at 54% conversion distilled to: F F 650 F+ 750 F+ 800 F+ 850 F+ Recycle streams at 54%, 58%, 68%, and 75% conversions distilled to F Quantity of each recycle stream measured from 1 st pass cracking Properties of each recycle stream determined Click to edit text styles 8

9 Incremental Yields of F Recycle Streams Boiling Range VGO ºF from VGO Resid ºF from Resid Dry Gas, wt% LPG, wt% C5+ Gasoline, wt% LCO, wt% Bottoms, wt% Coke, wt% F fractions from VGO made about the same LCO and bottoms as fresh VGO F fractions from resid made more LCO and LPG, less bottoms than fresh resid Click to edit text styles 9

10 Cracking Path of Hydrocarbon Molecules Percentage R R Di-aromatics R : hydrocarbons with less than 4 carbon atoms Mono-aromatics + Gasoline R R LCO Tri-aromatics + R Bottoms + R Coke Tetra-aromatics Saturates Mono-aromatics Di-aromatics Tri-aromatics Tetra-aromatics Click to edit text styles F Recycle Stream from VGO F Recycle Stream from Resid 10

11 Recycle Streams at 54% Conversion from Resid Properties API øf Conradson Carbon, wt.% % Vol% F Hydrogen, wt.% 12 Data Fresh Feed F F F 650F+ 750F+ 800 F+ 850 F F F F 650F+ 750F+ 800 F+ 850 F+ 600 Fresh Feed Click to edit text styles 9 Feed ID 11

12 ºF Recycle Stream vs. Conversion for Resid Properties Click to edit text styles 12

13 55 wt% conversion vs. % recycle in combined feed - Resid Key Yields 25.8 LCO, wt% 20.4 Bottoms, wt% Coke, wt% C5+ Gasoline, wt% F F F % 4% 8% 12% 16% 0% 4% % Recycle in Combined Feed 8% 12% 16% Click to edit text styles 13

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% Click to edit text styles 14

15 Maximum LCO Yields Fresh Feed Basis Resid Max Gasoline Base Base No Recycle F F F 650+ F Conversion Recycle Ratio Maximun recycle available Hydrogen, wt% Total C1's & C2's, wt% Propylene, wt% Total C3's, wt% Total C4='s, wt% Total C4's, wt% C5+ Gasoline, wt% RON MON LCO, wt% Bottoms Coke, wt% Click to edit text Max. styles Coke Allowed Limited by Max. Recycle Stream Limited by Max. Coke 15

16 Product Selectivity with and without Recycle Resid /850 F produces the highest LCO selectivity with slight coke penalty Yields on a fresh feed basis 20 Bottoms, wt% 52 C5+ Gasoline, wt% LCO, wt% Coke, wt% No Recycle Recy cle /850 Recy cle all F Click to edit text styles Conversion

17 Fresh Feed & Recycle Cracking Selectivity Resid 2 nd pass cracking of o F 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 Yields of 2nd pass cracking (Recycle Cracking) minus Yields of Fresh Feed Cracking 10 Max Recycle Ratio 0 C5+ Gasoline, wt% LCO, wt% Coke, wt% Click to edit text styles Conversion

18 Strategies for Maximizing FCC Light Cycle Oil Operating Strategies Recycle Catalyst Optimization Click to edit text styles 18

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 19

20 Design Concept for ACHIEVE 400 FCC Catalyst ACHIEVE 400 FCC Catalyst delivers higher LCO yield, greater gasoline octane, and improved C 4 = 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 20

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 F recycle stream Case 2 Optimized maximum LCO operation Click to edit text styles 21

22 Base Maximum Gasoline Operation Product Relative Price C3=, $/b C4=, $/b Gaso., $/b Base LCO, $/b Slurry, $/b 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 C 3+, Vol% FF Incremental $/b Base 22

23 Maximum LCO with ACHIEVE 400 FCC Catalyst 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) Reactor Temperature, F Air Blower, mscfm Constraint Constraint Constraint Wet Gas Compressor, scf/b Constraint ~90%Constraint Constraint LPG/Gaso., Vol% 23.8/ / /51.6 C4=, Vol% RON/MON 92.3/ / /80.4 LCO, Vol% FF Slurry, Vol% FF C 3+, Vol% FF Incremental $/b Base $0.08 $1.16 Volume swell is critical to maintaining profitability 23

24 Summary 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 The proper catalyst system, operating conditions and recycle ensure a profitable LCO operation 24

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. 25

26 Ann Benoit FCC Technical Service Representative Grace Catalysts Technologies 26