March 12th, 2008

Kinetic Study of Oil Shale Conversion

Pankaj TiwariDr. Milind Deo

Dr. Eric Eddings

Chemical Engineering Dept, University of Utah

March 12th, 2008

Table of contents

• Background• Previous studies

– Surface retorting– Shell’s ICP

• Study plan• Experiments

– TGA results– Retorting studies

• Conclusions

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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

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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

4Oil Shale Shale Oil

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Major world oil shale resources

5

Oil recovery varies depending upon the process and source material

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Major source of oil shale in USA

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•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

March 12th, 2008

Generalized process

Mining Crushing Retorting

Fracturing Retorting ProductRecovery

RefiningLiquid Fuels

By-Product

ATPGas combustion (Bureau, Petrosix)UnionToscoHydrogen AtmosphereKiviter Galoter

In-Formation

NaturalHydraulicExplosiveElectocarbonizationDrilling &Dewatering

CombustionHot gasesSteamGradual HeatingPyrolysis

Gas DriveArtificial Lift

Kerogen OilHydrocarbon Gases

Spent Shale

Underground Room & PillarCut and FillBlock Carving

Open-Pit

Thermal & Chemical TreatingHydrogenation

Mild-cat crackingHydrocracking

UtilizeDispose

Mine FillRevegetateDump

Source: Strategic Significance of America’s Oil Shale resources, Vol II, 2004

Control on Operational Parameter

Popcorn Process

Ex-Situ

In-Situ

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Pyrolysis Drum

Oil Shale Trommel Product

Spent Shale

Heater

RecycleCeramic

Ball

Air

GasHot Gas

FlueGas

TOSCO II (Surface process)

Source: An Assessment of Oil Shale Technology, 1980

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ProductCooling

Retorting

Combustion

HeatRecovery

Oil Shale

Spent Shale

Product Oil

Recycle Gas

Air

Gas combustion retort(Surface process)

Source: An Assessment of Oil Shale Technology, 1980

March 12th, 2008

PreheatFeed(Oil Shale) Retort Hydrocarbon

Vapors

Cooling Combustion Air

Spent ShaleHeat Exchange Heat

Flue Gas

Condensation

Steam Gas

Coked Solids

OilRecovery

Product

SulfurWater

Flue Gas

ATP Processor

Alberta taciuk processor (ATP)(Surface process)

Source: UMATEC and ATP, 2006

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Lean shale / Fracture porosityRich shale

Heaters

Producer

Tight overburdenLean shale / Fracture porosityRich shaleLean shale / Fracture porosityRich shaleLean shale / Fracture porosityRich shale

Freezing wall

Shell’s ICP

Source: www.shell.com

March 12th, 2008

In-situ product - Better feedstock for upgrading?

Tar Like Solid

Carbon Number

Wei

ght %

0 5 10

12

10

8

6

4

2

015 20 25 30 35 40 45 50 100 120

In Situ

800°CSurfaceRetort

SHALE OIL EXAMPLE

Naphtha - 30%Diesel - 30%Jet - 30%Resid - 10%

NAPHTHA JET DIESEL RESID

Source: www.shell.com (Stephen Mut, 2005)

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O/C (atomic ratio)

H/C

(ato

mic

ratio

)

0.1 0.2 0.3 0.4 0.5

0.5

1.0

1.5

2.0

III

III

Kerogen (Type I, II, III)

Utah Mahogany

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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

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First order reaction with respect to decomposition of the kerogen

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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 (250oC – 500oC)– Pressure (atm -2500 psi) – Heating Rate (100o C/ hours to 1oC/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 analysis15

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Pump

Mixing Unit

Reaction Chamber

N2

H2

CH4

Preheating

Equipment assembly, Upstream of the reaction chamber

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Reactor-1: Pyrolysis study of the crushed oil shale and shale core

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12’’7.5’’ 5.5’’5.0’’2.0’’1.5’’

Piston Cylinder 1.5’’ OD, 12’’ L

Gas diffusion plate

Gas diffusion plate

Core sample

Pressure sleeve

Pressure chamber

Heater element

Thermal insulation

Cylindrical rods

Top plate with holes

Gas outlet

Gas inlet

Thermocouple

Reactor-2: To measure the stresses induced during heating

March 12th, 2008

Gas

Condenser-2

Condenser-1

BPR

Vent Line

Pr Gauge

ReceiverProduct collector

Cleaning

Reactor Outlet

Gas Analyzer

Gas Sample

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Equipments assembly, downstream of the reaction chamber

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Experimental systemTemperature controller

Condensers

Reactor-1

Reactor-2

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Results: TGA analyses of oil shaleWeight loss/derivative versus Time/Temperature

Purge gas – 60ml/minWeight --~ 25 mgParticle size – ~100 mesh size

Non Isothermal- 1000oCIsothermal- 100oC/min

Purge Gas N2 AirTemperature/Ti

me300oC 720 min 240350 240 240400 240 240450 240 180500 240550 180600 30

Purge Gas- N2 AirHeating Rate

0.5oC/min1 Yes2 Yes-R Yes5 Yes10 Yes-R20 Yes-R50 Yes-R Yes

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TGA-reproducibility of data

Organic

Mineral

Data quite reproducible

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Isothermal-N2

600C

300C

•Weight loss increased as temperature increased•10-12% weight loss (TOC) at around 400-450 C

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600C

300C

Isothermal-N2 (with derivatives)

Mineral decomposition!

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600C

300C

Isothermal-N2 (versus temperature)

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Isothermal-Air

More weight loss compared to nitrogenat the same temperatures

Increasing temperatures

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Isothermal-Air

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Nonisothermal-N2

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Nonisothermal-N2

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Nonisothermal-Air

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Kinetic studyConversion –

α =

W0 = Initial weight of the sample, mgWt = Weight of the sample at time’ t’, mgW∞ = Weight of the sample at the end of the pyrolysis, mg

Arrhenius dependency : K = A. exp(-Ea/RT)

First order assumption

(W0 - Wt) / (Wo - W∞) = (W0 - Wt) / (Wo*x )

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Kinetic study for isothermal pyrolysis

IsothermalEnd

Integral MethodDifferential Method

300 C

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TstartTend

Rmax

Kinetic study for non-isothermal pyrolysis

Direct Arrhenius PlotChen & NuttallCoats & RedfernAnthony & Howard

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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 9.144ln(A) 10.85

A 51534.15 min-1R 8.314 J/molKEa 76.02322 KJ/mol

Isothermal N2- First order- Integral method

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P

Pyrolysis of oil shale - Setup

Gas Cylinder

Back Pressure Regulator

Vent line-1

Heater

Temperature Controller

Pressure GaugeCheck valve

Relief valve

Waste Container

PPressure GaugeSeparation unit

Product 1

Condenser-1

CoolingUnitCondenser-2

Gas Sampler

Product 2Product 3

Product 4

Vent line-2

Vent line-3

Flow meter

Insulation

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GC results• Two experiments

– 350oC – Crushed sample ( ~20gm and ~60gm)– 4 hours– N2

5.00 10.00 15.00 20.00 25.00 30.000

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000

2000000

2200000

Time

Response_

Signal: OSP1.D\FID1A.CHSignal: OSP2.D\FID1A.CH (*)

Signal: RETSTD4B.D\FID1A.CH (*)

C12 C14 C16 C18 C20 C22 C24 C26 C28 C30 C32 C36 C40 C44 C50 C60

Standard retention

First experiment

Second experiment

March 12th, 2008

GC results(Mountain West Energy Samples

Courtesy: Dr Shurtleff

Experiment_CH4

Second experiment_N2

5.00 10.00 15.00 20.00 25.00 30.00 35.000

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000

2000000

2200000

2400000

Time

Response_

Signal: OSP2.D\FID1A.CHSignal: OS1A.D\FID1A.CH (*) White river shale

March 12th, 2008

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

March 12th, 2008

Acknowledgement

• DOE Department of Energy• UHOP• PERC• Dr. Kyeongseok Oh • Dr. Kaushik Gandhi• Dr. Kevin Shurtleff

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March 12th, 2008

Thank You