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Hydroprocessing: Hydrotreating & Hydrocracking

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Hydroprocessing: Hydrotreating & Hydrocracking Hydroprocessing: Hydrotreating & Hydrocracking Chapters 7 & 9 Gases Polymer- Sulfur Sulfur ization Plant LPG Sat Gas Gas Plant Butanes Fuel Gas Alkyl LPG Feed Alkylation Gas Polymerization Separation & Naphtha Stabilizer Isom- erization Light Naphtha Alkylate Aviation Isomerate Gasoline Automotive Gasoline Reformate Naphtha Solvents Heavy Naphtha Hydro- Naphtha Reforming treating Naphtha Atmospheric Distillation Jet Fuels Kerosene Crude Desalter Kerosene Oil Distillate Cat Solvents Hydro- AGO Naphtha Distillate cracking Treating & Hydro- Heating Oils Blending treating Gas Oil Fluidized Cat Diesel LVGO Hydro- Catalytic treating Cracking Distillates Vacuum Distillation Fuel Oil HVGO Cycle Oils Residual Fuel Oils DAO Solvent Deasphalting SDA Coker Asphalts Bottoms Naphtha Naphtha Visbreaking Heavy Distillates Fuel Oil Coker Bottoms Gas Vacuum Lubricant Residuum Oil Lube Oil Solvent Greases Dewaxing Waxes Waxes Coking Light Coker Gas Oil Coke Updated: July 12, 2018 2 Copyright © 2017 John Jechura ([email protected]) U.S. Refinery Implementation of Hydrotreating EIA, Jan. 1, 2018 database, published June 2018 http://www.eia.gov/petroleum/refinerycapacity/ Updated: July 12, 2018 3 Copyright © 2017 John Jechura ([email protected]) U.S. Refinery Implementation of Hydrocracking EIA, Jan. 1, 2018 database, published June 2018 http://www.eia.gov/petroleum/refinerycapacity/ Updated: July 12, 2018 4 Copyright © 2017 John Jechura ([email protected]) Purpose Hydrotreating Hydrocracking . Remove hetero atoms & saturate . Severe form of hydroprocessing carbon‐carbon bonds • Break carbon‐carbon bonds • Sulfur, nitrogen, oxygen, & metals • Drastic reduction of molecular weight removed . Reduce average molecular weight & • Olefinic & aromatic bonds saturated produce higher yields of fuel . Minimal cracking products . Minimal conversion – 10% to 20% . 50%+ conversion typical . Products more appropriate for diesel . Products suitable for further than gasoline processing or final blending • Reforming, catalytic cracking, hydrocracking http://www.kbr.com/Newsroom/Publications/Brochures/Hydroprocessing‐Technology.pdf Updated: July 12, 2018 5 Copyright © 2017 John Jechura ([email protected]) Example Hydrogen Usage Refining Overview – Petroleum Processes & Products, by Freeman Self, Ed Ekholm, & Keith Bowers, AIChE CD‐ROM, 2000 Updated: July 12, 2018 6 Copyright © 2017 John Jechura ([email protected]) Characteristics of Petroleum Products Hydrocracking: hydrogen addition to minimize coke formation Refining Overview – Petroleum Processes & Products, by Freeman Self, Ed Ekholm, & Keith Bowers, AIChE CD‐ROM, 2000 Updated: July 12, 2018 7 Copyright © 2017 John Jechura ([email protected]) Characteristics of Petroleum Products Hydrotreating: just enough conversion to remove undesirable atoms; hydrogen addition for atom removal Refining Overview – Petroleum Processes & Products, by Freeman Self, Ed Ekholm, & Keith Bowers, AIChE CD‐ROM, 2000 Updated: July 12, 2018 8 Copyright © 2017 John Jechura ([email protected]) Hydroprocessing Trends Hydrogen is ubiquitous in Driven by several factors refinery & expected to . Increased use of increase hydrodesulfurization for low . Produces higher yields & sulfur fuels upgrade the quality of fuels . Heavier & higher sulfur crudes . Reduction in demand for heavy The typical refinery runs at a fuel oil hydrogen deficit . More complete protection of . As hydroprocessing becomes FCCU catalysts more prevalent, this deficit will . Demand for high quality coke increase . Increased production of diesel . As hydroprocessing progresses in severity, the hydrogen demands increase dramatically Updated: July 12, 2018 9 Copyright © 2017 John Jechura ([email protected]) Sources of Hydrogen in a Refinery By‐product from other processes Manufactured . Catalytic Reformer . Steam‐Methane Reforming (SMR) • Most important source of hydrogen • Most common method of for the refiner manufacturing hydrogen • Continuously regenerated reformer: • 90 – 95 vol% typical purity 90 vol% . Gasification / Partial Oxidation • Semi‐continuously regenerated • Produce synthesis gas (syngas) reformer: 80 vol% • Hydrogen recovery . FCCU Offgas o Pressure swing adsorption (PSA) • 5 vol% hydrogen with methane, o Membrane separation ethane & propane • More expensive than steam • Several recovery methods (can be reforming but can use low quality by‐ combined) product streams o Cryogenic o Pressure swing adsorption (PSA) o Membrane separation Updated: July 12, 2018 10 Copyright © 2017 John Jechura ([email protected]) Hydroprocessing Catalysts Hydrotreating Hydrocracking . Desired function . Crystalline silica alumina base with rare earth metals • Cobalt molybdenum – sulfur removal & olefin deposited in the lattice saturation • Platinum, palladium, tungsten, and/or nickel • Nickel molybdenum – nitrogen removal & aromatic • Rare earth metals typically mixture of lanthanum, saturation cerium, and other minor quantities . Reactor configuration • Acid function promotes the cracking • Downflow fixed bed – temperature to control final . Feed stock must first be hydrotreated sulfur content . Catalysts deactivate & coke forms even with hydrogen • First bed may guard bed for nickel & vanadium present o Cheaper catalysts • Hydrocrackers require periodic regeneration of the o Most removal of hetereo atoms in subsequent fixed bed catalyst systems beds • Channeling caused by coke accumulation a major . Selective catalysts for sulfur removal without olefin concern saturation • Can create hot spots that can lead to temperature • Maintaining high octane rating runaways . Reactor configuration • Fixed bed – typical for gas oil hydrocracking • Expanded circulating bed or slurry – proposed for resid hydrocracking Hydroprocessing catalysts https://grace.com/catalysts‐and‐fuels/en‐us/art‐ hydroprocessing‐catalysts Updated: July 12, 2018 11 Copyright © 2017 John Jechura ([email protected]) Reactor Bed Configurations Petroleum Refining Processes J.G. Speight & B. Özüm Marcel Dekker, Inc., 2002, pg. 452 Sample packing of catalyst on top of supports Model prepared by Enterprise Products Updated: July 12, 2018 12 Copyright © 2017 John Jechura ([email protected]) Gases Polymer- Sulfur Sulfur ization Plant LPG Sat Gas Gas Plant Butanes Fuel Gas Alkyl LPG Feed Alkylation Gas Polymerization Separation & Naphtha Stabilizer Isom- erization Light Naphtha Alkylate Aviation Isomerate Gasoline Automotive Gasoline Reformate Naphtha Solvents Heavy Naphtha Hydro- Naphtha Reforming treating Naphtha Atmospheric Distillation Jet Fuels Kerosene Crude Desalter Kerosene Oil Distillate Cat Solvents Hydro- AGO Naphtha Distillate cracking Treating & Hydro- Heating Oils Blending treating Gas Oil Fluidized Cat Diesel LVGO Hydro- Catalytic treating Cracking Distillates Vacuum Distillation Fuel Oil HVGO Cycle Oils Residual Fuel Oils DAO Solvent Deasphalting SDA Coker Asphalts Bottoms Naphtha Naphtha Visbreaking Heavy Distillates Fuel Oil Coker Bottoms Gas Vacuum Lubricant Residuum Oil Lube Oil Solvent Greases Dewaxing Waxes Waxes Coking Light Coker Gas Oil Coke Updated: July 12, 2018 13 Copyright © 2017 John Jechura ([email protected]) Hydrodesulfurization Sulfur Unsaturated carbon‐carbon bonds . Sulfur converted to hydrogen sulfide . Olefins saturated – one hydrogen (H2S) molecule added for each double bond • Added hydrogen breaks carbon‐sulfur • Olefins prevalent in cracked streams – bonds & saturates remaining hydrocarbon coker or visbreaker naphtha, catalytic chains cracker cycle oil, catalytic cracker gasoline . Form of sulfur bonds . Aromatic rings hydrogenated to • Sulfur in naphtha generally mercaptans cycloparaffins (naphthenes) (thiols) & sulfides • Severe operation • In heavier feeds, more sulfur as • Hydrogen consumption strong function of disulphides & thiophenes complexity of the aromatics . Light ends • prevalent in heavy distillate hydrotreating, • Heavier distillates make more light ends gas oil hydrotreating, hydrocracking from breaking more complex sulfur molecules Selective catalysts for hydrotreating cat gasoline for sulfur removal but not saturate olefins . Maintain high octane ratings Updated: July 12, 2018 14 Copyright © 2017 John Jechura ([email protected]) Hydrodesulfurization Chemistry H2 required & final hydrocarbon products dependent on position of sulfur in molecule CH3CH2CH2CH2CH2CH2CH2CH2‐SH + H2 → CH3CH2CH2CH2CH2CH2CH2CH3 + H2S CH3CH2CH2CH2CH2 ‐S‐CH2CH2CH3 + 2 H2 → CH3CH2CH2CH2CH3 + CH3CH2CH3 + H2S Saturation of molecules possible because of high H2 concentrations CH3CH2CH2CH=CHCH2CH2CH3 + H2 → CH3CH2CH2CH2CH2CH2CH2CH3 Ultra low sulfur levels difficult . Complex structures + 4 H2 → CH3CH2CH2CH3 + H2S . Mercaptan reversion CH3CH2CH2CH2CH2CH2CH=CH2 + H2S → CH3CH2CH2CH2CH2CH2CH2CH2‐SH Updated: July 12, 2018 15 Copyright © 2017 John Jechura ([email protected]) Yield Estimates Difficult to generalize because conversion of feedstock is relatively low Liquid products generally have volume & gravity increase – typically +1oAPI General relationship of hydrogen required vs. sulfur content . Naphtha: (scf/bbl H2) = 191 (wt% sulfur) – 30.7 . Middle distillates: (scf/bbl H2) = 110.7 (wt% sulfur) + 10.2 (% desulfurized) – 659.0 Petroleum Refinery Process Economics, 2nd ed., Fundamentals of Petroleum Refining, Robert E. Maples, 2000 by Fahim, Al‐Sahhaf, & Elkilani , Elsevier, 2010 Updated: July 12, 2018 16 Copyright © 2017 John Jechura ([email protected]) Typical Process Parameters http://www.eia.doe.gov/oiaf/servicerpt/ulsd/figd3.html Petroleum Refining Processes, by James G.
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