Download - The Influence of Specific Gravity Distributions on Fuel Properties

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


Fraction Run of Mine

(M1)

Fraction Refuse Dump

(M1)

1 Mass of Cogen Fuel

iMCogenFuel


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


Direct Cumulative


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


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


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%



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


Wt%

Direct Wt%

Cumulative Wt%Ash

The Specific Gravity Distribution of Ash Content- The Ugly

Anthracite Refuse (Active Mine in 1960’s)

Direct Cumulative


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


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


Wt% Direct Wt%

Cumulative Wt% Ash

Minerals in Coal WasteAnthracite Refuse- Specific Gravity Variations in Ash

Analysis

Wt% of Ash


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


Wt% Direct Wt%

Cumulative Wt% Ash

Minerals in Coal WastePittsburgh Seam Refuse- Specific Gravity Variations in Ash

AnalysisWt% of Ash


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

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


• Horsfall, Grobelaar, and Van Eck and Lurie (South Africa)– High Gravity Separations for Rerunning Coal

Refuse• Dense Medium Vessels

• Dense Medium Cyclones

• Other Systems


• 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



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


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


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


Wt%

Direct Wt%

Cumulative Wt%Ash

Makes Bottom AshMakes Flyash