Experimental Analysis of Multiscale Oil Shale Pyrolysis
Department of Chemical Engineering University of Utah, Salt Lake City, Utah
Pankaj Tiwari Milind Deo
October 19th, 2011
http://from50000feet.wordpress.com 1
Objectives
• Determine pyrolysis decomposition kinetics
• Measure compositions of the products during pyrolysis
• Characterization of the products evolved – Compositions and properties
• Study the impact of temperature and heating rate
• Understand the effect of scale
• Determine the effect of pressure
• Develop a kinetic model
2
Experimental study
• Samples – Mahogany zone of the Green River formation – Powdered, Cores of ¾”, 1” and 2.5” diameters
• Pyrolysis experiments – Batch, semi-batch, continuous flow – Temperature- 300 C to 500 C – Pressure ( ambient and 500 psi)
• Raw and product analyses – TGA, TGA-MS, CHNS, GC, GCMS – Spent shale analysis - Soxhlet extraction, coke
3
TGA analysis – Kinetic of the decomposition process
TGAMS analysis– Identification, quantification and kinetics of the products
Reactor pyrolysis – Yield and quality of the shale oil
Multiscales and pressure effects – Mass transfer and coke formation
Experimental analysis
Weight loss (raw-spent) shale
Oil yield
Gas loss (weight loss – oil yield)
Coke formation - TGA
Quality of products- GC
Elemental balance-CHSNO (Raw-Spent) shale
4
TGA analysis – Kinetic of the decomposition process
TGAMS analysis– Identification, quantification and kinetics of the products
Reactor pyrolysis – Yield and quality of the shale oil
Multiscales and pressure effects – Mass transfer and coke formation
Experimental analysis
Analysis of the materials
XRD,CHNSO and DSC on raw and spent shales
GC and GCMS on oil and gas
Single carbon number distribution of oil components and residual
Lumping of the components
Ratio of the products (oil/coke, condensable to non-condensable gases)
Physical property estimation
5
Effect of particle size Effect of flow rate
Environment: N2, He, Air and CO2
N2 pyrolysis – 100ml/min – Non-isothermal- 100 Mesh size
Thermal programs: Isothermal and non-isothermal
Raw material characterization- TGA
6
Organic – 17.5% Mineral -20.63%
Powdered sample
Organic – 11.5% Mineral -22.5%
Raw material characterization- TGA
Core sample different sections
Organic-12-30%
Core powdered sample
7
CHNSO Powdered oil shale Core_ powdered oil shale
wt % Stdev wt % Stdev
Carbon 17.45 0.26 22.09 1.00
Hydrogen 1.60 0.08 2.14 0.12
Nitrogen 0.53 0.06 0.65 0.06
Sulfur 0.18 0.04 0.11 0.02
Oxygen 15.69 0.79 16.54 0.97
H/C (molar) 1.10 ----- 1.17 -----
O/C (molar) 0.67 ----- 0.56 -----
Raw material- two different oil shales
Elemental analysis- CHNS-O
Type I kerogen
8
Powder oil shale
Core oil shale
Raw material-XRD results
Illite and Analcime release water 8% water of 5.84% 12% water of 2.38%
Significant mineralogical variations exist! 8% water of 2.84% 12% water of 4.13%
9
Coke Carbon
Raw oil shale Pyrolysis 500 C Pyrolysis 900 C Combustion-900 C
CHNSO CHNSO CHNSO CHNSO
Organic Carbon Mineral Carbon
Wt loss= 11.5% Wt loss= 22% ~0.005%
C % =10.02
H% =0.37
N% =0.562
S %=-0.008
O% = ---
C % = 16.08
H% =1.58
N% = 0.53
S %= 0.04
O% =15.69
C % =4.54
H% =0.48
N% =1.82
S %=0.17
O% = ---
C % =0.22
H% =0.05
N% =0.07
S %=0.006
O% = ---
Coke formation –powder sample
Solid material – Spent shale
Un-reacted organic
Mineral decomposition
Coke formation
Isothermal-400C-Ambient- Heat flow
N2
Air
Elemental constraints established
10
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
200 250 300 350 400 450 500 550
Nor
mal
ized
con
vers
ion
Temperature, oC
Expt-0.5C/min
Expt-1C/min
Expt-2C/min
Expt-5C/min
Expt-10C/min
Expt-20C/min
Expt-50C/min
TGA Application- Powdered samples-Oil Shale[Kerogen]
Non-isothermal pyrolysis [N2 – 100ml/min]
Transport effects are negligible [Particle -100 mesh size]
Overall (Global) reaction mechanism [Decomposition]
Weight loss Conversion
– Rates go from 0.5oC/min to
50oC/min.
Organic – 11.5%
11
Kinetic Results-[Organic Decomposition] Advanced isoconversional reaction model free method
Activation energy,- E
Pre-exponential factor -A
Seven heating rates – 0.5oC/min to 50oC/min [100 interval]
Overall decomposition mechanism – Distribution of kinetic parameters over conversion scale
0.E+00
1.E+14
2.E+14
3.E+14
4.E+14
5.E+14
6.E+14
7.E+14
8.E+14
9.E+14
1.E+15
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
A.f(α
), 1/
s
Extent of conversion
Distribution of A.f(α)
0
50
100
150
200
250
300
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Activ
atio
n en
ergy
, kJ/
mol
Extent of conversion
Distribution of activation energy
Tiwari and Deo. AIChE Journal (2011)
12
Reconstruction of Oil Shale Pyrolysis - [Kerogen]
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
200 250 300 350 400 450 500 550
Nor
mal
ized
con
vers
ion
Temperature, oC
Expt-0.5C/min
Simul-0.5C/min
Expt-1C/min
Simul-1C/min
Expt-2C/min
Simul-2C/min
Expt-5C/min
Simul-5C/min
Expt-10C/min
Simul-10C/min
Expt-20C/min
Simul-20C/min
Expt-50C/min
Simul-50C/min
Reconstruction of experimental data
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
100 200 300 400 500 600
Co
nv
ers
ion
Temperature, oC
Simul-0.01C_min
Simul-0.1C_min
Simul-10C_min
Simul-100C_min
Simul-500C_min
Extrapolation of experimental data
0.01oC/min to 500oC/min
iii RTEAfdtd ,, /)](ln[])/(ln[
Tiwari and Deo. AIChE Journal (2011) 13
Reaction Mechanism
Organic Matter Oill,g + Char + Gas + H20
Coke Gas Oil Gas Carbonaceous residue
Reaction Mechanism– Campbell [1978]
Reaction Mechanism #2 – Burnham and Singleton [1983] Organic Matter Oil (l,v,g) + Char + Gas [Oil generation] Oil (l) Oil (v) [Oil evolved] Oil (l) Mostly coke [Oil coking] Oil (v,g) Mostly gas [Oil cracking]
K1
K21
K4
K3
Reaction Mechanism #3 – Simplified approach for TGA and TGAMS data
Oil Shale (Kerogen) Products K
Light gases (K1) Naphtha grade oil (K2) Middle distillate grade oil (K3) Fuel Oil (K4) Residual (K5) Solid (K6)
Apparent kinetic parameters
K22
14
TGA-Chamber
MS
200 250 300 350 400 450 500 550 600
Temperature,oC
Ion cu
rrent
Benzene_5Cmin
Benzene_10Cmin
Hexane_5Cmin
Hexane_10Cmin
200 250 300 350 400 450 500 550 600
Temperature oC
Ion cu
rrent
Decane_10CminDecene_10CminDecyne_10CminButylbenzene_10Cmin
200 250 300 350 400 450 500 550 600
Temperature,oC
Ion cu
rrent
Benzene_5Cmin
Benzene_10Cmin
Hexane_5Cmin
Hexane_10Cmin
200 250 300 350 400 450 500 550 600
Temperature oC
Ion cu
rrent
Decane_10CminDecene_10CminDecyne_10CminButylbenzene_10Cmin
Thermal Gravimetric-Mass Spectrometry Analysis -[TGAMS]
Carbon # 6
Carbon # 10
Thermal behavior of selected products at different thermal programs
15
Oil Shale TGAMS Analysis- Product distribution
MS signal- 10 C/min
Relative Quantification of Products
Relat
ive co
ncen
tratio
n
5C/min
Section -250-600C
Methane Water CO2
MS signal- 5 C/min
58 70 72 78 84 86 92 98 100
106
110
112
114
120
128
134
138
140
142
148
156
164
170
178
184
212
228
254
260
278
280
282
294
296
Molecular weight, amu
10C/min
Section-250-600C
170
178
184
212
228
254
260
278
280
282
294
296
106
110
112
114
120
128
134
138
140
142
148
156
164
170
Hydrogen Methane Water Ethane H2S CO2_Propane
Thermogram area -base line correction
Tiwari and Deo, Fuel (2011) 16
Experimental setup
N2 preheating
P1
Ts2
T1
Reactor with sample, heater and insulator
BPR
CompressedN2 Tank-1 Rotameter
Ts1
Check valve
Back pressure regulator
Pressure relief valve
Vent line
P2
N2 line to pressurize the autosamplers
CompressedN2 Tank-2
Gas sampling
Liquid sampling MF-2
Condensers
V1
V4
MF-1
Mass flow meter
V2 V3
V6
V7V8
V9
V10
Mass flow meter 2
V35
17
Cores– ¾”, 1” and 2.5” diameter
Ambient isothermal pyrolysis – Heat supply-controlled from center temperature (3/4” core)
OS = Oil shale, SS = Spent shale, SO = Shale oil
0.021.6195.792.360.652.3410.7279.72SO_300C
0.021.6495.711.930.622.3410.9179.91SO_350C
0.021.6596.822.130.652.0511.1080.89SO_400C
1.350.3840.2425.420.010.260.4414.12SS_300C
1.110.7036.2820.870.020.470.8214.10SS_350C
1.610.1941.5427.990.010.270.2113.06SS_400C
0.561.1741.5316.540.110.652.1422.09OS_Core
O/C (molar)
H/C (molar)TotalO %S %N %H %C %Samples
0.021.6195.792.360.652.3410.7279.72SO_300C
0.021.6495.711.930.622.3410.9179.91SO_350C
0.021.6596.822.130.652.0511.1080.89SO_400C
1.350.3840.2425.420.010.260.4414.12SS_300C
1.110.7036.2820.870.020.470.8214.10SS_350C
1.610.1941.5427.990.010.270.2113.06SS_400C
0.561.1741.5316.540.110.652.1422.09OS_Core
O/C (molar)
H/C (molar)TotalO %S %N %H %C %Samples
300C 350C
5 .0 0 1 0 .0 0 1 5 .0 0 2 0 .0 0 2 5 .0 0 3 0 .0 0 3 5 .0 0 4 0 .0 0 4 5 .0 00
2 0 0 0 0
4 0 0 0 0
6 0 0 0 0
8 0 0 0 0
1 0 0 0 0 0
1 2 0 0 0 0
1 4 0 0 0 0
1 6 0 0 0 0
1 8 0 0 0 0
2 0 0 0 0 0
2 2 0 0 0 0
2 4 0 0 0 0
2 6 0 0 0 0
T i m e
R e s p o n s e _
S ig n a l: 1 2 J u ly 0 8 _ 3 0 0 C .D \ F ID 1 A .C HS ig n a l: 1 7 J u n e 0 8 _ 3 0 0 C .D \ F ID 1 A .C H
5 . 0 0 1 0 . 0 0 1 5 . 0 0 2 0 . 0 0 2 5 . 0 0 3 0 . 0 0 3 5 . 0 0 4 0 . 0 00
2 0 0 0 0
4 0 0 0 0
6 0 0 0 0
8 0 0 0 0
1 0 0 0 0 0
1 2 0 0 0 0
1 4 0 0 0 0
1 6 0 0 0 0
1 8 0 0 0 0
2 0 0 0 0 0
2 2 0 0 0 0
T i m e
R e s p o n s e _
S ig n a l: 1 9 Ju n e 0 8 _ 3 5 0 C .D \ F ID 1 A .CHS ig n a l: 2 1 Ju ly0 8 _ 3 5 0 C .D \ F ID 1 A .CH
5 .0 0 1 0 .0 0 1 5 .0 0 2 0 .0 0 2 5 .0 0 3 0 .0 0 3 5 .0 0 4 0 .0 0 4 5 .0 0
3 0 0 0 0
3 5 0 0 0
4 0 0 0 0
4 5 0 0 0
5 0 0 0 0
5 5 0 0 0
6 0 0 0 0
6 5 0 0 0
7 0 0 0 0
7 5 0 0 0
8 0 0 0 0
8 5 0 0 0
9 0 0 0 0
9 5 0 0 0
T i m e
R e s p o n s e _
S ig n a l: 2 5 J u n e 0 8 _ 4 0 0 C .D \ F ID 1 A . C HS ig n a l: 2 9 J u ly 0 8 _ 4 0 0 C .D \ F ID 1 A .C H
5 . 0 0 1 0 . 0 0 1 5 . 0 0 2 0 . 0 0 2 5 . 0 0 3 0 . 0 0 3 5 . 0 0 4 0 . 0 0
3 0 0 0 0
3 5 0 0 0
4 0 0 0 0
4 5 0 0 0
5 0 0 0 0
5 5 0 0 0
6 0 0 0 0
6 5 0 0 0
7 0 0 0 0
T im e
R e s p o n s e _
S ig n a l : B la n k A . D \ F I D 1 A . C HS ig n a l : 4 t h E X P _ 4 5 0 C . D \ F I D 1 A . C H
400C 450C
Temp Oil Yield % Weight loss %
Pyrolysi_Reactor Un-reacted % Coke %
300C 6.56 10.11 4.81 0.42
350C 6.75 14.00 0.50 2.72
400C 10.29 21.92 0.69 4.80
GC-Shale oil
TGA-Spent shale
0
5
10
15
20
25
300C 350C 400C 300C 350C 400C
Weight loss%
Oil Yield%
Oil yield
18
OS = Oil shale, SS = Spent shale, SO = Shale oil
0.021.6195.792.360.652.3410.7279.72SO_300C
0.021.6495.711.930.622.3410.9179.91SO_350C
0.021.6596.822.130.652.0511.1080.89SO_400C
1.350.3840.2425.420.010.260.4414.12SS_300C
1.110.7036.2820.870.020.470.8214.10SS_350C
1.610.1941.5427.990.010.270.2113.06SS_400C
0.561.1741.5316.540.110.652.1422.09OS_Core
O/C (molar)
H/C (molar)TotalO %S %N %H %C %Samples
0.021.6195.792.360.652.3410.7279.72SO_300C
0.021.6495.711.930.622.3410.9179.91SO_350C
0.021.6596.822.130.652.0511.1080.89SO_400C
1.350.3840.2425.420.010.260.4414.12SS_300C
1.110.7036.2820.870.020.470.8214.10SS_350C
1.610.1941.5427.990.010.270.2113.06SS_400C
0.561.1741.5316.540.110.652.1422.09OS_Core
O/C (molar)
H/C (molar)TotalO %S %N %H %C %Samples
•More residue (heavy components) was observed with increase in the temperature
Elemental analysis
Ambient isothermal pyrolysis- ¾” cores
19
0
0.1
0.2
0.3
9 14 19 24 29 34 39 44
Wei
gh
t F
ract
ion
Carbon Number
Single Carbon Number (SCN) Distribution
of Shale Oil- Isothermal Iso_500C_Ambient
Iso_400C_Ambient
Iso_300C_Ambient
Iso_500C_500Psi
Iso_400C_500Psi
Iso_300C_500Psi
0
0.1
0.2
9 14 19 24 29 34 39 44
Wei
gh
t F
ract
ion
Carbon Number
Single Carbon Number (SCN) Distribution
of Shale Oil- Non-isothermal
1Cmin_500Psi
1Cmin_Ambient
10Cmin_Ambient
Effect of the pressure- 3/4” Core
Reactor surface is the controlling temperature probe
Shale oil compositions
20
Effect of the pressure- 3/4” Core
21
Lumped oil components
0.49 0.34
0.17 0.07
0.18 0.09
0.38
0.17 0.15
0.42
0.54
0.65
0.55 0.33 0.44
0.53
0.42 0.34
0.09 0.12 0.17
0.38 0.48 0.47
0.09
0.41 0.51
Fractions of Shale Oil Fuel Oil
Middle Distillate
Naphtha Isothermal-500Psi Isothermal- Ambient
Non-isothermal
22
0.562.16
32.45
0.47
9.21 10.30
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00Oil/Coke
Oil/Coke
3.99
7.818.36
0.001.002.003.004.005.006.007.008.009.00
Oil/Coke
Oil/Coke
0.55 0.60
4.08
15.40
0.49 0.03
9.86
24.69
2.57
0.00
5.00
10.00
15.00
20.00
25.00
30.00
(C4-C12)/(C1-C3)
(C4-C12)/(C1-C3)
Effect of the pressure- 3/4” Core
Condensable to non-condensable gas ratio
Chromatograms of oil product- FID with Restek MXT-1 column
Comparison of the different scale pyrolysis products
Results 2.5" core 3/4" core
Wt loss % 24.52 18.69
Oil yield % 7.96 10.63
Coke % 6.06 1.03
Overall mass balance-
Two different scales (3/4” and 2.5”) were performed (500 C for 24 hrs) under high pressure, 500psi.
2.5" core 3/4" core
Single carbon number (SCN) distribution
23
min2 4 6 8 10 12 14 16
pA
0
25
50
75
100
125
150
175
200
FID1 A, (E :\RESEARCH\CURRENT W O RK\G C ANLAYSIS-2010\O CT G C EG I\10100G .D)
m in2 4 6 8 10 12 14 16
25 uV
0
25
50
75
100
125
150
175
200
T CD2 B, (E :\RESEARCH\CURRENT W O RK\G C ANLAYSIS-2010\O CT G C EG I\10100G .D)
m in2 4 6 8 10 12 14 16 18
pA
0
500
1000
1500
2000
2500
3000
3500
4000
4500
FID1 A, (E :\RESEARCH\CURRENT W O RK\G C ANLAYSIS-2010\NEW DAT A\T EDLAR\10097G .D) T CD2 B, (E :\RESEARCH\CURRENT W O RK\G C ANLAYSIS-2010\NEW DAT A\T EDLAR\10097G .D)
FID-blue
TCD- blue
Chromatogram of gaseous products- TCD and FID detectors in series
3/4” sample- spitted TCD and FID detectors response
Comparison of the different scale pyrolysis products
2.5” sample- overlaid TCD (red) and FID (Blue) detectors response
2.5” - 500C_500Psi ¾” -500C_500Psi
Images of spent shales
24
Challenges
• The heterogeneity in the raw material makes analyses complicated.
• Well-controlled isothermal and non-isothermal operations at large scale
are difficult.
• Quantification of secondary reactions.
• Complex/coupled multiphysics involved in the process.
25
Oil shale Core-Skyline 16
Core samples from Skyline 16 drilling by UGS and ICSE. (Courtesy, Dr Lauren at EGI) 26
GR 1-3
Sample No Samples ID Mass, mg Organic % Mineral % Coke %
1 461.2- 462.2 18.16 21.13 17.86 1.63
2 485.9-486.9 17.01 7.2 29.85 0
3 548.2-549.2 23.11 11.16 20.43 0.34
TGA weight loss data of all three samples
Sample No. Sample ID C % H % N % S %
1 461.9-462.9 33.93 3.21 1.17 0.56
2 485.9-486.9 19.80 1.40 0.473 0.13
3 548.1-549.1 20.44 1.84 0.709 0.18
Elemental analysis (CHNS) of all three samples
(3) 548.1-549.1 (2) 485.9-486.9
(1) 461.9- 462.9
Skyline 16- Three different sections
27
0
5
10
15
20
25
30
35
Weight loss % Oil yiled % Gas loss%
350C
425C
500C
GR-1 GR-2 GR-3
350 C
500 C
500 C
500 C
425 C
350 C
425 C
425 C
350 C
a
b
c
Isothermal for 24 hrs Hot N2 flow from top
Skyline 16- 1” dia and 6” long
GR-1 GR-2 GR-3
(1) 461.9- 462.9 (2) 485.9-486.9
Pyrolysis of core samples
(3) 548.1-549.1
28
0
2
4
6
8
10
12
14
Weight loss % Oil yiled % Gas loss%
350C
425C
500C
0
2
4
6
8
10
12
14
16
18
20
Weight loss % Oil yiled % Gas loss%
350C
425C
500C
3C-425C
3a- 500C
3b- 350C
2a- 425C
2b-500C
2c-350C 1a-350C
1b- 425C
1C- 500C
Skyline 16- Spent shale
29
Summary
• TGA-MS can be used to provide the kinetics of individual and lumped components.
• Pyrolysis at larger scales can be used to understand temperature distributions and
the effect of secondary reactions on the product yield and quality.
• Characterization of the raw and product material is required to perform accurate
material balances.
• Heterogeneity in the samples can be significant and must be recognized.
• Increase in temperature accelerates kerogen decomposition.
• Increase in the size of the core and pressure result in the formation of lighter oil,
but the yield is reduced. More coke is formed under these conditions.
• Density (0.89-0.91 g/cc), WAT ( 16-19 API), Viscosity (3.21-5 cP at 30 C)
• High pressure produces oil of lower WAT and lower viscosity. 30
Department of Energy [DOE] – Financial support
Member of Institute for Clean and Secure Energy [ICSE]
Member of Petroleum Research Center [PERC]
Utah Geological Survey – Samples
Acknowledgement
31
