FCC Gasoline Treating Using Catalytic Distillation. Texas Technology Showcase March 2003, Houston, Texas. Dr. Mitchell E. Loescher

Transcription

1 F Gasoline Treating Using atalytic Distillation Texas Technology Showcase March 2003, Houston, Texas Dr. Mitchell E. Loescher

2 Gasoline of the Future Lead is out Olefins reduced Aromatics reduced Benzene reduced Sulfur reduced

3 Gasoline Desulfurization Requirements Pool sulfur specification Europe European Union 50 ppm max ppm max - available standard 2008 US, anada 30 ppm avg to 2008 Future ppm?

4 Sulfur Sources F Naphtha 200 to 3000 ppm 25 to 40% of refinery pool volume 85 to 99% of refinery pool sulfur

5 F Gasoline Feed omposition Sulfur, ppm Temperature, Olefins, % Sulfur Olefins

6 Optimized HDS Process LN Mild HDS F 5+ GASOLINE MN Medium HDS MN/HN HN Severe HDS

7 onventional LN Treating 5+ ASOLINE LN FRESH AUSTI Mercaptan Removal Selective Hydrogenation Hydrogen ompression SPENT AUSTI MN/HN TREATED LN HYDROGEN Fractionate LN from F Gasoline austic wash for mercaptan removal ~90% effective Selective hydrogenation of dienes for alky/ethers ompression of makeup hydrogen

8 Hydrogenation / Distillation Replace trays with structured distillation packing containing catalyst Add Hydrogen Feed Vent excess Hydrogen DHydro Process Hydrogen Hydrocarbon Feed W Steam Vent Gas Treated Distillate Bottoms

9 DHydro Reactions Thioetherification + SH S Selective Hydrogenation + H H

10 DHydro Reactions Isomerization RON 118

11 DHydro Reactions Isomerization RON Hydroisomerization boosts full range F naphtha by 0.5 RON

12 atalytic Distillation H2 Reflux atalyst Section Drawing Vapor Wire Mesh atalyst

13 Optimized F Naphtha HDS LN Hydrogen DHydro F 5+ GASOLINE MN/HN HDS

14 onventional MN/HN HDS Make-up Hydrogen Reactors Recycle Hydrogen Light Ends Stripper W Light Ends LP Steam F Gasoline Low Sul F Gasoline

15 onventional Reactor Design Severity of reactor conditions set by most refractory species Temperature H 2 partial pressure Lighter sulfur species react to very high conversions All olefins exposed to the most severe conditions Reactors

16 onventional Fixed Bed HDS 100 onversion (%) Total S Light S Heavy S Olefin 1 Olefin Reactor Length Olefin 1 - with recombinant mercaptan in product Olefin 2 - w/o recombinant mercaptan

17 Recombinant Mercaptan Experience Mercaptan Levels fixed bed RSH RSH Level, ppm Octane Loss (R+M)/2

18 Optimized F Gasoline HDS LN Mild HDS F 5+ GASOLINE MN Medium HDS MN/HN HN Severe HDS

19 F Gasoline Octane Distribution 92 Octane No., (R+M)/ Boiling Point,

20 MN/HN with DHDS onditions milder than conventional fixed bed (17 barg vs 28+) > 99% HDS Heavy sulfur to bottom Light olefins to top Min octane 90% HDS) F 7+ Gasoline DHDS W Off Gas Low H2 consumption Low sulfur bottoms product good for gasoline No yield loss due to cracking No makeup compressor No mid-cycle shutdown for catalyst regen No feed storage required Hydrogen

21 Selectivity urve onversion, Fraction Temperature, F Sulfur reduction Olefin reduction Olefin saturation is higher for heavy olefins

22 Octane vs. arbon Number RON Linear Olefin - Linear Saturate RON arbon Number

23 Why is DTEH s octane loss lower? onventional fixed bed hydrotreaters Saturate primarily light olefins Light olefin saturation causes high octane loss DHDS Higher saturation of heavy olefins Less octane to lose in heavy olefins Lower octane loss at a given olefin reduction

24 Fixed Bed HDS atalyst Life? F turnaround cycle Modern refineries target 5 year cycle onventional fixed bed hydrotreaters Olefins form oligomers Oligomers form coke that fouls catalyst atalyst activity reduced Regenerate or replace catalyst Must shutdown before end of F cycle Fixed bed catalyst life insufficient

25 ommercial atalyst Activity for F Gasoline HDS Relative Activity Fixed Bed HDS Days on Oil

26 atalyst Activity History for ommercial DHDS Units Observed Rate onst Days Since Start-up Irving Oil Motiva hevrontexaco

27 onventional Fixed Bed Unit Shutdown F unit x Sulfur Reduction Unit Untreated F Gasoline storage

28 onventional Unit Restart F unit x Sulfur Reduction Unit Extra apacity Required Untreated F Gasoline storage

29 onclusions DHydro Lowest sulfur and diolefins in LN Eliminates separate mercaptan and diolefin removal units DHDS Lowest F cycle olefin loss via HDS No cracking yield loss No diene pretreatment required No regeneration/feed storage required DHydro/DHDS Lowest overall octane loss ommercially proven Most cost effective HDS in FR F N Long catalyst life via catalytic distillation Low capital cost

30 Recommendations Plan for 10 ppm sulfur Evaluate full F cycle performance Include shutdown related capital cost Thank you to DOE for 1980 funding for R&L