the influence of specific gravity distributions on fuel properties
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The Influence of Specific Gravity Distributions on Fuel Properties
Pete Rozelle
U.S. Department of Energy
ARIPPA, October 31, 2006
The Influence of Specific Gravity Distributions on Fuel Properties
• Ash Content Distributions in Coal Refuse by Specific Gravity
• Distributions of Mineral and Ash Components
• Example of Using these Things to get a Cost Advantage for a CFB Power Plant
• Turning Bad Material into Useful Fuel (an Example)
Attributes that Vary with Specific Gravity
• Ash Content
• Mineral Content
• Particle Density
• Ash Chemistry
• Ash Fusion Characteristics
• Where the Stuff Ends up in a CFB Boiler (Ash Split)
The Math of Summing Fuel Properties - an Example Using Ash Content
Run of Mine Refuse Dump Cogen Fuel
250 Tons 750 Tons 1000 Tons
15% Ash
1.4% S
50% Ash
3.5% S
41.3% Ash
3.0% S
The Math of Summing Fuel Properties - an Example Using Ash Content
Fraction Run of Mine
(M1)
Fraction Refuse Dump
(M1)
1 Mass of Cogen Fuel
iMCogenFuel
The Math of Summing Fuel Properties - an Example Using Ash Content
Fraction Run of Mine X Ash Content of
Run of Mine
(M1A1)
Fraction Refuse Dump X Ash Content of
Refuse Dump
(M2A2)
Ash Content of Cogen Fuel
iiAMAshCogenFuel %_
The Specific Gravity Distribution of Ash Content- the Float Sink Table
Direct Cumulative Float
Sink Float Wt% Ash% Sulfur% Wt% Ash% Sulfur%
1.30 25.12% 4.03% 1.19% 25.12% 4.03% 1.19%
1.30 1.40 36.29% 8.25% 1.46% 61.41% 6.52% 1.35%
1.40 1.50 7.66% 18.76% 2.26% 69.07% 7.88% 1.45%
1.50 1.60 2.70% 28.13% 3.24% 71.77% 8.64% 1.52%
1.60 28.23% 47.37% 5.33% 100.00% 19.57% 2.59%
B Seam Run of Mine, Cambria County, Pa
The Specific Gravity Distribution of Ash Content- One Way to Look at it
B Seam Run of Mine, Cambria County, Pa
0.0%
5.0%
10.0%
15.0%
20.0%
25.0%
30.0%
35.0%
40.0%
1.29 1.35 1.45 1.55 2.7
Mean Specific Gravity
Wt% Direct Wt%
CumulativeAsh%
The Specific Gravity Distribution of Ash Content
B Seam Refuse Dump, From the ROM in the Last Slide
Direct Cumulative
Sink Float Wt% Ash% S% Wt% Ash% S%
1.40 15.9% 6.9% 1.4% 15.9% 6.9% 1.4%
1.40 1.50 2.5% 19.7% 3.3% 18.4% 8.6% 1.6%
1.50 1.60 2.4% 29.3% 2.9% 20.8% 11.0% 1.8%
1.60 1.70 3.6% 38.9% 2.2% 24.4% 15.1% 1.9%
1.70 1.80 6.9% 49.0% 1.5% 31.3% 22.6% 1.8%
1.80 2.00 17.7% 58.1% 1.6% 49.0% 35.4% 1.7%
2.00 51.0% 78.9% 5.0% 100.0% 57.6% 3.4%
The Specific Gravity Distribution of Ash Content- One Way to Look at it
B Seam Refuse Dump, Cambria County, Pa
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
1.3 1.45 1.55 1.65 1.75 1.9 3.5
Direct Wt%
Cumulative Float Ash
Float Sink Tables for Refuse Dumps
• The Good:– Deep Mined, Flat Coal
– Not Dense Medium Cleaned
– Old
• The Bad:– Newer
– Refuse Quality wasn’t under the Microscope
• The Ugly:– Surface Mining of Old Workings
– Pitched Coal
– Dense Medium Cleaning
The Specific Gravity Distribution of Ash Content- The Good
B Seam Refuse Dump, Cambria County, Pa
Direct Cumulative
Sink Float Wt% Ash% S% Wt% Ash% S%
1.40 8.5% 6.5% 1.1% 8.5% 6.5% 1.1%
1.40 1.50 5.7% 21.8% 1.5% 14.2% 12.6% 1.2%
1.50 1.60 15.6% 31.2% 1.4% 29.7% 22.4% 1.3%
1.60 1.70 21.7% 39.6% 1.5% 51.5% 29.7% 1.4%
1.70 1.80 13.6% 47.9% 1.6% 65.0% 33.5% 1.4%
1.80 2.00 11.8% 55.3% 2.7% 76.8% 36.8% 1.6%
2.00 23.5% 67.2% 11.6% 100.3% 43.9% 4.0%
The Specific Gravity Distribution of Ash Content- The Good
B Seam Refuse Dump, Cambria County, Pa
0.0%
5.0%
10.0%
15.0%
20.0%
25.0%
30.0%
35.0%
40.0%
45.0%
50.0%
1.3 1.45 1.55 1.65 1.75 1.9 3.5
Direct Wt%
Cumulative Ash %
The Specific Gravity Distribution of Ash Content- The Bad
Pittsburgh Seam Refuse Dump (Old)
Direct Cumulative
Sink Float Wt% Ash% S% Wt% Ash% S%
1.40 18.6% 9.2% 1.5% 18.6% 9.2% 1.5%
1.40 1.50 4.1% 21.3% 3.8% 22.7% 11.3% 1.9%
1.50 1.60 3.2% 27.7% 3.9% 25.9% 13.4% 2.2%
1.60 1.70 2.9% 37.5% 4.3% 28.7% 15.8% 2.4%
1.70 1.80 2.1% 43.1% 4.2% 30.9% 17.7% 2.5%
1.80 2.00 3.7% 52.8% 4.9% 34.6% 21.5% 2.8%
2.00 65.4% 86.2% 3.7% 100.0% 63.8% 3.4%
The Specific Gravity Distribution of Ash Content- The Bad
Pittsburgh Seam Refuse Dump (Old)
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
1.35 1.45 1.55 1.65 0.175 1.9 2.5
Mean Specific Gravity
Wt%
Direct Wt%
Cumulative Wt%Ash
The Specific Gravity Distribution of Ash Content- The Ugly
Anthracite Refuse (Active Mine in 1960’s)
Direct Cumulative
Sink Float Wt% Ash% S% Wt% Ash% S%
1.60 1.4% 9.4% 0.8% 1.4% 9.4% 0.8%
1.60 1.70 1.0% 26.4% 1.1% 2.4% 16.4% 0.9%
1.70 1.80 5.5% 37.3% 1.0% 7.9% 30.9% 1.0%
1.80 2.00 19.2% 49.7% 1.2% 27.1% 44.2% 1.1%
2.00 72.9% 81.3% 1.4% 100.0% 71.2% 1.3%
The Specific Gravity Distribution of Ash Content- The Ugly
Anthracite Refuse (Active Mine in 1960’s)
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
1.55 1.65 1.75 1.9 2.8
Mean Specific Gravity
Wt% Direct Wt%
Cumulative Wt% Ash
Minerals in Coal Waste
• Illite:
– K3(Al6FeMg)(Si14Al2)O40(OH)8
• Kaolinite
– Al2O3·2SiO2·2H2O
• Pyrophyllite
– Al2O3·2SiO2·H2O
• Pyrite
– FeS2
• Rutile
– TiO2
Minerals in Coal WasteExample of Mineral Content Variations by
Specific Gravity- An Anthracite Bank
Wt% of Mineral Matter
Sink Float Wt% Illite KaolinitePyrophylliteKaolinite Quartz Pyrite Rutile
1.60 1.4% 26.8% 66.2% - 2.4% 1.3% 3.3%
1.60 2.00 12.7% 37.4% 49.4% - 9.2% 1.5% 2.5%
2.00 2.40 42.9% 39.9% 41.8% - 14.8% 1.9% 1.6%
2.40 2.60 32.8% 28.7% - 30.8% 36.7% 2.9% 0.9%
2.60 10.2% 45.1% - 38.4% 7.2% 8.3% 1.0%
Minerals in Coal WastePittsburgh Seam Refuse- Specific Gravity Variations in Ash
AnalysisWt% of Ash
Sink Float Wt% Wt% Ash SiO2 Al2O3 Fe2O3 CaO MgO
1.4 17.0% 7.8% 58% 26% 12% 1.6% 0.1%
1.4 1.6 4.9% 17.7% 50% 18% 20% 2.7% 0.1%
1.6 1.8 5.9% 40.0% 42% 17% 16% 11.0% 1.5%
1.8 2 2.8% 50.7% 44% 17% 17% 11.0% 1.4%
2 2.2 2.7% 59.3% 51% 16% 21% 4.0% 0.1%
2.2 2.4 4.6% 69.6% 54% 19% 20% 4.0% 0.1%
2.4 2.6 10.7% 82.4% 61% 23% 12% 1.8% 0.1%
2.6 2.8 45.2% 88.7% 57% 22% 6% 1.7% 0.1%
2.8 2.96 1.6% 66.1% 24% 9% 60% 1.7% 0.0%
2.96 4.6% 61.3% 11% 2% 83% 1.2% 1.6%
Minerals in Coal WasteAnthracite Refuse
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
1.5 1.7 1.9 2.1 2.3 3.5
Mean Specific Gravity
Wt% Direct Wt%
Cumulative Wt% Ash
Minerals in Coal WasteAnthracite Refuse- Specific Gravity Variations in Ash
Analysis
Wt% of Ash
Sink Float Wt% Wt% Ash SiO2 Al2O3 Fe2O3 CaO MgO
1.6 4.9% 17.7% 54% 25% 11% 0.7% 0.1%
1.6 1.8 5.9% 40.0% 55% 24% 6% 0.3% 0.6%
1.8 2 2.8% 50.7% 55% 27% 6% 0.3% 0.1%
2 2.2 2.7% 59.3% 55% 24% 5% 0.3% 0.1%
2.2 2.4 4.6% 69.6% 55% 29% 4% 0.5% 0.1%
2.4 2.6 10.7% 82.4% 55% 28% 4% 0.7% 0.1%
2.6 2.8 45.2% 88.7% 55% 27% 6% 0.8% 0.1%
2.8 2.96 1.6% 66.1% 31% 13% 54% 2.8% 2.1%
2.96 4.6% 61.3% 12% 3% 75% 1.5% 1.7%
Minerals in Coal WasteWest Virginia Refuse
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
1.35 1.5 1.7 1.9 2.1 3
Mean Specific Gravity
Wt% Direct Wt%
Cumulative Wt% Ash
Minerals in Coal WastePittsburgh Seam Refuse- Specific Gravity Variations in Ash
AnalysisWt% of Ash
Sink Float Wt% Wt% Ash SiO2 Al2O3 Fe2O3 CaO MgO
1.4 17.0% 7.8% 50% 28% 17% 2.0% 0.1%
1.4 1.6 4.9% 17.7% 54% 26% 13% 1.4% 0.1%
1.6 1.8 5.9% 40.0% 55% 26% 11% 1.9% 0.1%
1.8 2 2.8% 50.7% 56% 25% 10% 1.2% 0.1%
2 2.2 2.7% 59.3% 57% 23% 7% 1.1% 0.1%
2.2 2.4 4.6% 69.6% 58% 25% 7% 0.6% 1.1%
2.4 2.6 10.7% 82.4% 56% 23% 6% 0.3% 1.5%
2.6 2.8 45.2% 88.7% 57% 24% 6% 0.2% 1.5%
2.8 2.96 1.6% 66.1% 26% 9% 52% 1.1% 0.5%
2.96 4.6% 61.3% 7% 2% 90% 0.4% 0.0%
Mineral and Ash Analyses Vary with Specific Gravity- What about Fusion
Temperatures?Degrees F
Sink FloatWt%Ash
Initial Deformation Temperature
SofteningTemperature Fluid Temperature
1.45 1.7% 2,720 2,720 2,820
1.45 1.50 2.8% 2,890 2,910+ -
1.50 1.55 7.8% 2,910+ - -1.55 1.60 15.7% 2,360 2,410 2,460
1.60 1.65 16.2% 2,340 2,390 2,490
1.65 1.70 24.3% 2,250 2,300 2,350
1.70 1.75 26.7% 2,190 2,250 2,300
1.75 1.80 31.6% 2,210 2,260 2,310
1.80 1.85 34.5% 2,340 2,390 2,490
1.85 1.90 42.9% 2,520 2,570 2,700
1.90 69.7% 2,120 2,160 2,200
Anthracite
An Example of Getting a Cost Advantage for a CFB Power Plant
• Not all Potential Fuel is Located Close to the Power Plant
• Low Quality Materials May not Make Sense to Truck Long Distances
• Improved Fuel Quality can:– Reduce Transportation Costs– Reduce Limestone requirements– Reduce Ash Disposal Costs– Increase Mean Bed Residence Time
Economics of Waste Coal Reprocessing
)Y1(CY
)CC(C r
ofp
Cp Product Cost/tonCf Feedstock Cost/tonCo Plant Operating Cost/ton FeedCr Refuse Disposal Cost/ton
Y Plant Yield
Example of the Effect of Product Quality on Production Cost
$-
$5.00
$10.00
$15.00
$20.00
$25.00
$30.00
$35.00
$40.00
15 20 25 30 35 40 45
Product Wt% Ash
Pro
duct
ion
Cos
t P
er T
on
Effect of Fuel Quality on Tonnage Requirements (100 MW CFB Power Plant)
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
15 20 25 30 35 40 45
Fuel Wt% Ash
Ton
s pe
r Y
ear
FuelLimestoneAsh
Fuel, Limestone, and Ash Costs for a 100 MW CFB Power Plant (Example)
$-
$2,000,000
$4,000,000
$6,000,000
$8,000,000
$10,000,000
$12,000,000
$14,000,000
15 20 25 30 35 40 45Fuel Wt% Ash
An
nu
al C
ost
Fuel Cost
Limestone Cost
Ash Cost
Fuel, Limestone, Ash Total Cost for 100 MW CFB Power Plant (Example)
$-
$2,000,000
$4,000,000
$6,000,000
$8,000,000
$10,000,000
$12,000,000
$14,000,000
15 20 25 30 35 40 45
Fuel Wt% Ash
An
nu
al C
ost
Fuel, Limestone, Ash Total Cost for 100 MW CFB Power Plant (Example)
$-
$2,000,000
$4,000,000
$6,000,000
$8,000,000
$10,000,000
$12,000,000
$14,000,000
15 20 25 30 35 40 45
Fuel Wt% Ash
An
nu
al C
ost
Examples of the Application of Coal Preparation Vessels to Coal Refuse
• Dense Medium Cyclone- Commonwealth of Pennsylvania, 1960’s:– Feed Ash Content: 56 wt%– Cyclone Feed Gravity =1.80, Product = 20%
Yield, 38% Ash– Cyclone Feed Gravity = 1.90, Product = 28%
Yield, 42% Ash
Examples of the Application of Coal Preparation Vessels to Coal Refuse
• Horsfall, Grobelaar, and Van Eck and Lurie (South Africa)– High Gravity Separations for Rerunning Coal
Refuse• Dense Medium Vessels
• Dense Medium Cyclones
• Other Systems
Examples of the Application of Coal Preparation Vessels to Coal Refuse
• Water Only Cyclone- Penn State University– Feed: up to 30% Ash– Product at 30% Ash Feed = 20% Ash
Potential Economics of Prepared Fuel from Low Quality Coal Refuse
• Simulation for the Following:– Coarse Coal Dense Medium Vessel (1.60 to 1.80
Gravity)– Dense Medium Cyclones (1.60-1.90 Feed Gravity)– Generic Process for Recovery of -28 Mesh
Material
Potential Economics of Prepared Fuel from Low Quality Coal Refuse Dump
• Assumptions:– Royalty = $1.00/Raw Ton– Load and Carry Cost = $1.00/Raw Ton– Prep Plant Cost= $2.50/Raw Ton– Prep Plant refuse Cost = $0.50/Ton
The Specific Gravity Distribution of Ash Content- The Bad
Pittsburgh Seam Refuse Dump (Old)
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
1.35 1.45 1.55 1.65 0.175 1.9 2.5
Mean Specific Gravity
Wt%
Direct Wt%
Cumulative Wt%Ash
64 Wt% Ash
3.3 Wt% S
Potential Economics of Prepared Fuel from Low Quality Coal Refuse Dump (Pittsburgh)
• Results:– 24 Wt% Ash– 2.5 Wt% S– ~$0.72/MM BTU Production Cost
• Blended with Run of Bank (65/35) Yields:– 34 Wt% Ash– 2.8 Wt% S– ~$0.60/MM BTU Production Cost
The Specific Gravity Distribution of Ash Content
B Seam Refuse Dump, Cambria County, Pa
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
1.3 1.45 1.55 1.65 1.75 1.9 3.5
Direct Wt%
Cumulative Float Ash
64 Wt% Ash
3.3 Wt% S
Potential Economics of Prepared Fuel from Low Quality Coal Refuse Dump (B Seam)
• Results:– 30 Wt% Ash– 2.1 Wt% S– ~$0.62/MM BTU Production Cost
What about Currently Produced Prep Plant Refuse?
• Pittsburgh Bed Refuse from Active Operation in 1988- As Sampled:– 49 Wt% Ash– 5.5 Wt% Sulfur
What about Currently Produced Prep Plant Refuse?
• Pittsburgh Bed Refuse from Active Operation in 1988- As Sampled:– 49 Wt% Ash– 5.5 Wt% Sulfur
• After a Laboratory Process:– 65% Yield– 41 Wt% Ash– 3.9 Wt% Sulfur
Up Next:
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
1.35 1.45 1.55 1.65 0.175 1.9 2.5
Mean Specific Gravity
Wt%
Direct Wt%
Cumulative Wt%Ash
Makes Bottom AshMakes Flyash
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