Constant Pressure Retorting of Oil Shale Earl D. Mattson, Carl D. - - PowerPoint PPT Presentation

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Constant Pressure Retorting of Oil Shale

Earl D. Mattson, Carl D. Palmer

30th Oil Shale Symposium In Situ Processing October 19, 2010 Idaho National Laboratory

Objective: Conduct laboratory constant back pressure oil shale retorting experiments to evaluate the effects of process variables (gas pressure and temperature)

• n produced fluids.

Approach: Retort 150 g crushed oil shale samples in a high pressure/temperature vessel under isothermal and constant pressure conditions. Compare quantity and quality of produced oil, gas, and spent shale.

Heat Heat

Product

Retort Gas/Liquid Pressure Energy Input + Time (Temperature Distribution)

Major In Situ Controls

Constant Pressure Laboratory Set-up

shale

References Bae, 69 Noble et al. 81, 82 Burnham et al. 82 Yang and Sohn, 85

Max Temp 600°C, Max Pressure 600 psi

TGA Results – Raw vs Retorted Shale

• 10°C per min
• Nitrogen purge
• Ambient to 575°C
• < 1 mm particle size

~15% wt loss ~2% wt loss Retorted Raw

Decomposition Temperature Ranges Kerogen Bitumen Dolomite/Calcite

Temperature Effects

t = exp(13901*(1/(T+273))-16.61)

Results as Function of Temperature

Pressure = 200 psi Time = 144, 24, 4 hrs Higher Temperature

• More oil generated
• More gas generated
• More mass removed

Oil Quality

Increasing Temperature

TGA Results – Effect of Temperature

Lower retorting temperature => less mass removal

Variable Back Pressure Tests

• Crushed oil shale
• Isothermal (500°C)
• 4 hr testing
• Variable Back Pressure

– 25 to 540 psi

Pressure Control

Results as Function of Back Pressure

Temp = 500°C Time = 24 hrs @ Higher Back Pressure

• Less oil generated
• Approximately same gas
• More mass removed

Transport vs Decomposition Kinetics Gas Sorption

Sequential Sampling Results Retort Pressure 540 psi Four samples after finished Lighter gases tend to adsorb to spent shale Methane ~3X increase Ethane ~2X increase

Oil Quality

Increasing Pressure

TGA Results – Effect of Pressure

greater gas back pressure => change in distribution

Water Invasion

• Fisher Assay type test
• Ramp and Soak (500°C)
• ~2 hr testing
• Back Pressure 25 psi
• With and with/out water addition

Fischer Assay

• Container type
• Container size (L)
• Sample mass (g)
• Sample size (mesh)
• Ramp rate (oC/min)
• Backpressure (psig)
• Alum.
• 1/3
• 95 (+/-10)
• 8
• 12
• SS
• 1
• 218.8
• 4-10
• ~7
• 20-30

Reported FA INL “FA”

FA Results

• Red – no water
• Blue – 2 ml/min

FA - Comparison

w/o H2O w/ H2O

Gas Chromatograph Results – FA Comparison

w/o H2O w/ H2O No difference in oil quality

TGA Results – FA Comparison

Summary Comparison of pressure controlled laboratory results

• Const. Pressure – Var. Temperature (200 psi, 350-500°C)

– At higher retorting temperatures – Possible issue with reaction kinetics

– More oil generated – More gas generated – More mass removed – Slightly better quality

• Const. Temperature – Var. Back Pressure (500°C, 25-540 psi)

– At higher back pressures

– Less oil generated – Approximately same gas volume – Less mass removal – Better quality

Summary (cont.)

• Transport issues at high pressure

– Spent shale appears to adsorb gases similar to CBM – CO2 storage (~0.04 lbs CO2 per ton shale per psi)

• Water Intrusion Effects

– Fisher Assay Results

– More oil generated ?? – Same amount of gas generated – Same amount of mass removed – Distribution of kerogen and bitumen may be different (TGA) – No difference in oil quality – More H2 and CO2 produced with H2O addition

• These preliminary results suggest

– Operate in situ retorts at lower back pressure without

water