Kinetic Study of Oil Shale Conversion Pankaj Tiwari Dr. Milind Deo Dr. Eric Eddings Chemical Engineering Dept, University of Utah
Table of contents Background Previous studies Surface retorting Shell s ICP Study plan Experiments TGA results Retorting studies Conclusions
Oil shale Older than petroleum There is no oil in the shale. Organic matter Bitumen (soluble in organic solvent) Kerogen (significant portion of TOC) Mineral constitutes: - Carbonates: calcite, dolomite 3
Oil shale: Source of unconventional energy Organic matter Kerogen, A chemically immature hydrocarbon - essentially, oil's geological ancestor Chemical decomposition- Released petroleum-like substance Pyrolysis (retorting) In-Situ retorting Surface retorting Products include Synthetic crude oil liquid Gases Residual solid Oil Shale Shale Oil 4
Major world oil shale resources Oil recovery varies depending upon the process and source material 5
Major source of oil shale in USA Green River Formation 1.8 TBs of producible oil 25 gl /ton of raw material, The Piceance Basin in Colorado contains deposits more than 500 feet in thickness and located under 500-2000 feet of sedimentary rock www.petroprobe.com 6
Generalized process Ex- Situ Underground Room & Pillar Cut and Fill Block Carving Open-Pit Mining Crushing Retorting ATP Gas combustion (Bureau, Petrosix) Union Tosco Hydrogen Atmosphere Kiviter Galoter Spent Shale Utilize Dispose Mine Fill Revegetate Dump Thermal & Chemical Treating Hydrogenation Mild-cat cracking Hydrocracking Refining Popcorn Process Liquid Fuels By-Product In- Situ Fracturing Natural Hydraulic Explosive Electocarbonization Drilling & Dewatering In-Formation Retorting Combustion Hot gases Steam Gradual Heating Pyrolysis Product Recovery Gas Drive Artificial Lift Kerogen Oil Hydrocarbon Gases Control on Operational Parameter Source: Strategic Significance of America s Oil Shale resources, Vol II, 2004
TOSCO II (Surface process) Heater Air Flue Gas Hot Gas Recycle Ceramic Ball Gas Oil Shale Pyrolysis Drum Trommel Product Spent Shale Source: An Assessment of Oil Shale Technology, 1980
Gas combustion retort (Surface process) Oil Shale Product Cooling Product Oil Spent Shale Retorting Combustion Heat Recovery Recycle Gas Air Source: An Assessment of Oil Shale Technology, 1980
Alberta taciuk processor (ATP) (Surface process) Condensation Product Steam Gas ATP Processor Feed (Oil Shale) Preheat Retort Hydrocarbon Vapors Oil Recovery Heat Exchange Heat Coked Solids Spent Shale Sulfur Water Flue Gas Flue Gas Cooling Combustion Air Source: UMATEC and ATP, 2006
Shell s ICP Producer Heaters Freezing wall Tight overburden Lean shale / Fracture porosity Rich shale Lean shale / Fracture porosity Rich shale Lean shale / Fracture porosity Rich shale Lean shale / Fracture porosity Rich shale Source: www.shell.com
In-situ product - Better feedstock for upgrading? March 12 th, 2008 Weight % 12 10 8 6 4 In Situ NAPHTHA JET DIESEL RESID SHALE OIL EXAMPLE 800 C Surface Retort Naphtha - 30% Diesel - 30% Jet - 30% Resid - 10% 2 Tar Like Solid 0 0 5 10 15 20 25 30 35 40 45 50 100 120 Carbon Number Source: www.shell.com (Stephen Mut, 2005)
Kerogen (Type I, II, III) H/C (atomic ratio) 2.0 1.5 1.0 0.5 Utah Mahogany I II III 0.1 0.2 0.3 0.4 0.5 O/C (atomic ratio)
Previous studies: Mechanism Proposed model Kerogen Bitumen Oil +Gas + Residue Kerogen Bitumen + Oil +Gas + Residue Bitumen Oil +Gas + Residue Free radical mechanism And many others First order reaction with respect to decomposition of the kerogen 14
Experimental plan Comprehensive thermogravimetric analyses (TGA) Reactors Experiments with crushed oil shale samples Oil generation from shale cores Effect of retorting on rock samples (stress and permeability creation) Pretreatment and analysis of raw material Pyrolysis at different reaction conditions Temperatures (250 o C 500 o C) Pressure (atm -2500 psi) Heating Rate (100 o C/ hours to 1 o C/hours) Types of Gas ( Inert, hydrogen donor, combination) Sweep gas flow rate (low to high??) Pyrolysis time (5 hours to few weeks or months) Products analysis 15
N 2 Equipment assembly, Upstream of the reaction chamber H 2 Pump Preheating Mixing Unit Reaction Chamber CH 4 16
Reactor-1: Pyrolysis study of the crushed oil shale and shale core 17
Reactor-2: To measure the stresses induced during heating Gas inlet Piston Cylinder 1.5 OD, 12 L Top plate with holes Gas diffusion plate Core sample Thermocouple Pressure sleeve Pressure chamber Heater element Gas diffusion plate Thermal insulation Cylindrical rods 7.5 5.0 1.5 2.0 5.5 Gas outlet 12
Equipments assembly, downstream of the reaction chamber March 12 th, 2008 Reactor Outlet Gas Vent Line Gas Analyzer Pr Gauge BPR Gas Sample Cleaning Condenser-1 Condenser-2 Product collector Receiver 19
Experimental system Temperature controller Reactor-1 Condensers Reactor-2
Results: TGA analyses of oil shale Weight loss/derivative versus Time/Temperature Purge gas 60ml/min Weight --~ 25 mg Particle size ~100 mesh size Isothermal- 100 o C/min Non Isothermal- 1000 o C Purge Gas N2 Air Temperature/Ti me 300 o C 720 min 240 350 240 240 400 240 240 450 240 180 500 240 550 180 600 30 Purge Gas- N2 Air Heating Rate 0.5 o C/min 1 Yes 2 Yes-R Yes 5 Yes 10 Yes-R 20 Yes-R 50 Yes-R Yes
TGA-reproducibility of data Organic Mineral Data quite reproducible
Isothermal-N 2 300C 600C Weight loss increased as temperature increased 10-12% weight loss (TOC) at around 400-450 C
Isothermal-N 2 (with derivatives) 300C 600C Mineral decomposition!
Isothermal-N 2 (versus temperature) 300C 600C
Isothermal-Air More weight loss compared to nitrogen at the same temperatures Increasing temperatures
Isothermal-Air March 12 th, 2008
Nonisothermal-N 2 March 12 th, 2008
Nonisothermal-N 2 March 12 th, 2008
Nonisothermal-Air March 12 th, 2008
Kinetic study Conversion α = (W 0 -W t ) / (W o -W ) = (W 0 -W t ) / (W o *x ) W 0 = Initial weight of the sample, mg W t = Weight of the sample at time t, mg W = Weight of the sample at the end of the pyrolysis, mg Arrhenius dependency : K = A. exp(-ea/rt) First order assumption
Kinetic study for isothermal pyrolysis Integral Method Differential Method 300 C Isothermal End
Kinetic study for non-isothermal pyrolysis Direct Arrhenius Plot Chen & Nuttall Coats & Redfern Anthony & Howard R max T start T end
Isothermal N 2 - First order- Integral method Ln(1-X) Vs. Time,min K,/min ToC T, K 1000/T,K ln(k) R2 0.009 300 573.5 1.743679-4.71053 0.623 0.019 350 623.5 1.603849-4.13517 0.972 0.034 400 673.5 1.484781-3.38139 0.984 0.303 450 723.5 1.38217-1.19402 0.719 Ea/1000R 9.144 ln(a) 10.85 A 51534.15 min-1 R 8.314 J/molK Ea 76.02322 KJ/mol
Pyrolysis of oil shale - Setup March 12 th, 2008 Vent line-1 Relief valve Flow meter Pressure Gauge P Check valve Insulation Heater Vent line-2 Gas Cylinder Temperature Controller Gas Sampler Vent line-3 Product 4 Condenser-1 Separation unit Back Pressure Regulator Pressure P Gauge Product 3 Condenser-2 Product 2 Cooling Unit Product 1 Waste Container
GC results Two experiments 350 o C Crushed sample ( ~20gm and ~60gm) 4 hours N 2 Response_ 2200000 Signal: OSP1.D\FID1A.CH Signal: OSP2.D\FID1A.CH (*) Signal: RETSTD4B.D\FID1A.CH (*) 2000000 1800000 1600000 1400000 1200000 1000000 800000 600000 400000 Second experiment First experiment Standard retention 200000 Time 0 5.00 10.00 15.00 20.00 25.00 30.00 C12 C14 C16 C18 C20 C22 C24 C26 C28 C30 C32 C36 C40 C44 C50 C60
Response_ GC results (Mountain West Energy Samples Courtesy: Dr Shurtleff March 12 th, 2008 2400000 2200000 Signal: OSP2.D\FID1A.CH Signal: OS1A.D\FID1A.CH (*) White river shale 2000000 1800000 1600000 1400000 1200000 1000000 800000 600000 Second experiment_n2 400000 200000 Experiment_CH 4 Time 0 5.00 10.00 15.00 20.00 25.00 30.00 35.00
Conclusions and status TGA analyses Consistent sets of isothermal and non-isothermal data Kinetic parameters comparable to those found in the literature Retorting experiments Good product quality Similar in quality to methane retorting environment Variety of reactors designed and built to study kinetics, diffusion, mass transfer and stress effects
Acknowledgement DOE Department of Energy UHOP PERC Dr. Kyeongseok Oh Dr. Kaushik Gandhi Dr. Kevin Shurtleff 39
Thank You March 12 th, 2008