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Coal-water slurry: A status report
Energy Vol. 11, No. 11/12, pp. 1157-1162, 1986 Printed in Great Britain
COAL-WATER
0360-5442/86 $3.00 +O,OO Pergamon Journals Ltd
SLURRY: A STATUS REPORT ROLF
Electric
Power
Research
Institute,
K.
MANFRED
3412 Hillview
Avenue,
Palo Alto, CA 94303, U.S.A.
Abstract-During the years of oil shortage and rapidly increasing oil prices, the need to decrease dependence on oil-fired utility boilers became an urgent concern. The alternatives were to: (1) build new coal-fired stations; (2) modify oil-fired boilers to fire pulverized coal; (3) modify oil-fired boilers to fire coal slurry; (4) modify boilers to fire deeply cleaned, finely pulverized coal; or (5) fire coalderived liquids. Of these alternatives, the use of the coal-water slurry (CWS) promised a combination of advantages: near-term readiness, low-fuel costs compared to oil, moderate conversion costs, and low technical/economic risks. The development work sponsored and peformed since 1979 with coal-water slurries (70 wt % coal, 29 wt % water, 1 wt % additives) has confirmed these expectations. Fuel quality guidelines and test standards have been established, production of CWS in 40,000150,OOOton/yr pilot plants has been demonstrated, utility-scale burner systems (100 MBtu/hr) have been demonstrated, and the effects and costs of modifying typical utility boilers have been predicted. Limited field handling, storage, and use tests were completed successfully. The remaining hurdles to commercial acceptance, such as the establishment of slurry quality control procedures and confirmation of predicted boiler performance as well as conversion economics, can best be resolved by conducting a test in a utility boiler.
BACKGROUND
coal-water slurry (CWS) has been developed in recent years as a way to increase the efficient use of coal. The two main types of coal-water slurries are those developed for long-distance transportation (CWST) and those that can be fired directly as a fuel (CWSF). Both types of coal slurries have developed to the point of commercial readiness. The transportation slurry concept is used at the Salt River Project, the Nevada Power Company, and the Los Angeles Department of Water and Power and Southern California Edison’s Mojave Station where CWST with about 50% coal and 50% water is transported by pipeline for several hundred miles from the mine to the power station. After partial dewatering, the coal is pulverized and fired. The coal-water slurry that can be fired as a fuel contains about 70 wt % water, and 1 wt % additives and can be fired directly almost as if it were heavy fuel oil. The development of CWSF has progressed rapidly and the technology is ready for widespread commercial use.l,’ Both of these slurry types, as well as their variations and derivatives (Table l), were developed to reduce U.S. dependence on foreign fuels and to reduce fuel costs-in the case of the pipeline slurry through lower transportation costs and in the case of the slurry fuel by substitution for more expensive oil. The pace of commercial growth of both types of coal slurries has been disappointing, however, to those of us who have been committed to their development. The issues delaying the further deployment of transportation pipelines are complex, due to political and competitive factors, and will be discussed in detail by other speakers at this conference. Most of my remarks will concern the future of coalwater slurry fuel whose deployment has been slowed by the perceived changes in oil availability, by reduction in oil consumption, and by dropping oil prices. As a result, the current price differential in favor of CWSF is not large enough to motivate potential users to switch. In addition, the perceived risk of changing from an “old” to a “new” fuel and the uncertainty of future energy scenarios make it difficult for processors who must scale up production from existing pilot plants to production plants to raise venture capital and the resulting chicken-and-egg problem between slurry processor and slurry user continues to hinder market growth. Despite the present plateau in the commercial growth of CWSF, however, the future still holds considerable promise. The market will grow if one or a combination of five scenarios occurs (Table 2). I will consider these scenarios individually in the following sections. The
1157
1158
ROLF K. MANFRED Table 1. Types of coal-water
slurries and their uses, benefits, and applications
Coal-water Description
Use
Main benefit
Application
50% coal/50% water
Pipeline transportation
Lower transportation
cost
Old and new coal-design boilers
70% coa1/29% water/l % additives
Direct fired fuel
Costs less than No. 6 oil
Old oil-design boilers
60% coal/40% water. Direct-fired fuel
Pipeline transportation; dewatering (no additives)
Cheaper process (no dewatering; no additives)
Old and new coal-design boilers
Ultraline coal slurry
Direct fired fuel
Reduced derating
Oil- and gas-design boilers
Ultraclean coal slurry
Direct fired fuel
Reduced derating
Oil- and gas-design boilers
Coke-water slurry
Direct fired fuel
Cheaper fuel
Marine boilers
Dense lower-rank coal slurry
Direct fired fuel
Cheaper fuel
Gasifws, fluid beds, slagging combustors
Coal/CO, slurry
Pipeline transportation
No water required
Oil and new coal-design boilers
Coal/alcohol slurry
Direct-fired fuel or transportation slurry
Both slurry components are fuels
Old oil-design boilers
Table 2. Scenarios for CWS market improvement, Increases in oil prices Reduction in CWSF costs Reduction in boiler derating Improvement in coal quality Establishment of domestic and export market clusters Reduction in conversion risks
INCREASES
IN OIL
PRICES
Predictions of long-term oil price trends have been notoriously poor. The current price differential between No. 6 oil at about $29/barrel, or $4.6/MBtu, and CWSF, at $3.2/MBtu (delivered to a typical user site), is $1.4/MBtu. If the boiler and plant conversion costs and predicted boiler capacity losses are then taken into account this price differential represents a near breakeven point and the demand for CWSF will be small (Fig. 1). As the price differential increases, the market potential increases. Estimates, based on the capacity, location, age, and configuration of existing utility boilers, show that the utility market could be as large as 40,OOOMWe (Fig. 1). This could include about 15,OOOMWe of coaldesign boilers that now burn oil and cannot convert to pulverized coal. The oil-design boilers consist of configurations that range from “liberal” conventional designs that may not require derating to increasingly “tight” configurations (Fig. 2) that may have to be substantially derated.3 An increase in oil prices may open a utility retrofit market for all or part of this total, depending on the savings for a given site. If one assumes all of the candidate market to be available, this could represent sales of a total of 84 million tons of slurry per year, or 59 million tons of coal per year. If these speculations hold true, then the utility market could be expected to start growing at a faster rate as the price of No. 6 oil rises to about $3l/barrel and is perceived to have bottomed out.
REDUCTION
IN CWSF
COSTS
Another scenario for increasing the rate of market growth for coal-water slurry fuel could be to reduce its delivered cost. When surveyed, CWS processors predict being able to deliver slurry to typical utility user sites for about $3.2/million Btu. This delivered slurry price includes the cost of coal feedstock of about $1.4/million Btu, about $0.6/million Btu for transportation of the coal from mine to a slurry processing site, and $0.3/millionBtu for CWSF transportation to the user site by rail or barge. Differences in quotes are due mostly to differences in coal feedstock quality, the cost of processing, and user site location.
Coal-water
slurry: a status report
Eqwalent
Utility Retrofit Market (MW[e])
4.1 0.9
4.3
4.5
Mt/yr of CWSF
5.1
5.3
1.9 ($/MBtu)
2.1
4.9
4.7
No. 6 oil price ($/MBtu) 1.7 1.5 1.1 1.3 Differential Price (No. 6 OILCWSF)
1159
Assumptions
Fig. 1. Potential
BOX
effect of oil price changes
on CWSF
CLOSE
TYPE
market
COUPLED
growth.
SCREEN
a
CLOSE
COUPLED
CONVENTIONAL
ARCH
TYPE
b a
Burners: a Gas outlet : b Fig. 2. Typical
boiler configurations.
ROLF K. MANFRED
1160
1. Minemouth
2. Process plant at transport
process plant
hub
6
Power plant 3. Across-the-fence
Fig. 3. Transportation
process plant
scenarios
for conveying
4. Long distance
coal to slurry processing
pipeline
site and slurry to user site.
Reduction of the delivered CWSF price would significantly enhance the marketability of slurry. There is leeway in locating the processing plant to minimize transportation and waste disposal costs. (Fig. 3). Therefore, the selection of the most economical means of conveying coal to the slurry processing site and slurry to the user site is one of the most important, and as yet not fully identified, cost reduction areas. Electric Power Research Institute is sponsoring a study with Texas Eastern Corporation to compare rail, barge, and pipeline options.4 Finally, the judicious selection of effective, low-priced additives or reduction of additive concentration levels should be pursued further to reduce slurry costs. REDUCTION
IN BOILER
CAPACITY
LOSSES
AND
IMPROVEMENT
IN COAL
QUALITY
The costs of converting boilers and plants from firing oil to firing CWS have been estimated by various engineering firms at about %lOO-!§300/kW. In addition, however, the reduced capacity (derating) of converted boilers must be considered (Table 3). The range in boiler conversion costs is due mostly to (1) site-specific differences for installation of particulate control systems, (2) the extent of modifications to be made to specific boilers, and (3) boiler size. The modifications are necessary due to the slagging, fouling, and erosion behavior of coal. It is assumed that scrubbers will not be required, that the boilers remain capable of firing oil at nameplate rating, and that life expectancy is not reduced. Most of the conversion costs are unavoidable, but it may be possible to minimize boiler capacity losses by adjusting the slurry quality or effecting boiler use changes (Table 4). Physical and chemical processes for reducing the ash and sulfur concentrations of coal are in development. Several slurry processors have already incorporated coal cleaning steps into their slurry preparation processes. With many different coals, significant reductions in ash (typically to the 4% level) and sulfur level (80% reduction in pyritic sulfur) have been reported with good carbon recovery. The effect of ultrafine grinding of coal in reducing fly ash particle size has been experimentally confirmed by studies sponsored by Northeast Coal Utilization Project and
Coal-water
slurry: a status report
1161
Table 3. Summary of case study units
Firing typeb
Rating oo CWS % of nameplate capacity
Utility
Unit
Capacity (ME,) contiguration”
Boston Edison consumers Power Debnarva Florida Power and light Houston Lightning and Power Mississippi Power Corporation Virginia Electric and Power
Mystic 7 Karn 3 Edge Moore 5
565/CC screen 62O/box 4lO/box
T W W
60/50 70/50 40140
Sanford 4
4OO/CC arch
W
85/85
Sam Bertron 1
180/C
arch
W
75160
waston 3 Yorktown 3
112/conv. 845/CC arch
T T
lOO/lOO 70153
(Slurry A/B3
‘Cow = conventional design; CC screen = close-coupled screen; CC arch = close-coupled arch. bT = tangential firing; W = wall firing. ?&nry A prepared with low-slagging coal and Slurry B with medium-slagging coal.
Table 4. Approaches to minimizing boiler capacity losses Capacity Losses Current
Target
5-15%
>3%
80% < 200 mesh 90%<3OOu
100% < 325 mesh 100% < 175u
Approach Slurry modifications Reduce coal ash content Improve coal slagging/properties Use find coal grinds Improve atomization (reduce droplet size) Boiler modifications Implement more extensive initial boiler modi6cations Switch fuels Decrease tube life expectancy
-
conducted by Stone and Webster with Babcock and Wilcox. It is hoped that fine fly ash (with low carbon content) will result in reduced slagging, fouling, and tube erosion and reduced boiler capacity losses (derating). The beneficial effects of improved atomization have been demonstrated recently by Babcock and Wilcox, under EPRI sponsorship, with a lO@MBtu/hr burner. In this test 99.5% carbon burnout was achieved. The cost and effects of more than currently assumed modifications to boilers or changes in boiler operation tactics are being studied by utilities, engineering firms, and boiler companies.
ESTABLISHMENT
OF
DOMESTIC
AND
EXPORT
MARKET
CLUSTERS
The design and sales management of a slurry processing plant can be made to be costeffective if different market demands can be satisfied from a central location. The resulting economy, of course, cannot occur until such diverse markets exist, but the preparation of plans and estimates is necessary to promote market growth.
REDUCTION
IN
CONVERSION
RISKS
The perception of risk, i.e. the unknowns of fuel dependability and quality control; the unforeseen aspects of daily transportation, handling and storing operations; and the unconfirmed effects on the boiler of combustion, have a retarding effect on market growth. The technology has progressed to the point where a significant demonstration in a sufficiently large, oil-design utility boiler is needed. EPRI, DOE, and private industries have produced the technology for such a demonstration. We are co-operating with our
1162
ROLF K. MANFRED
member utilities, with government agencies, engineering firms, and the transportation demonstration.
and with slurry vendors, boiler companies, industry to initiate and conduct such a
SUMMARY
The current state-of-the-art of coal-water slurry fuel is such that no major technical problems are apparent. The growth of a substantial market is held back by a breakeven cost differential between No. 6 oil and CWSF at present oil prices. Commercialization will also await the performance of a large demonstration test. The present oil to slurry price differential of about $1.4/MBtu must be increased to about $1.7/MBtu before the market starts to grow and must increase to over $2.0/MBtu before full market development can be realized. Approaches to achieve such an increase in price differential can be identified and must be pursued. A significant hurdle will be overcome if sufficient backing can be gathered for a demonstration test in a large boiler. REFERENCES 1. J. P. Dooher, “Coal-Water Slurry Pumping and Flow Tests”, Electric Power Research Institute, Palo Alto, Calif. Rep. G-3722 (1984). 2. R. D. Perkins, “Coal-Water Slurry Test in an Industrial Boiler”, Electric Power Research Institute, Palo Alto, Calif. Rep. CS-4268 (1985). 3. E. Kirnel and R. Kurtzrock, “Comparison of Coal Conversion Alternatives”, in Proceedings ofthe Department of Energy Fifth International Symposium on Coal-Slurry Combustion and Technology, U.S. Department of Energy, Washington, D.C. (1983). 4. 0. Rogers, C. Durbidge and R. Manfred, “Coal-slurry Fuel Transportation Alternatives”, in Proceedings of the Department of Energy Seventh Annual International Symposium on Coal-Slurry Fuels, U.S. Department of Energy, Washington, D.C. (1985).
COAL-WATER
0360-5442/86 $3.00 +O,OO Pergamon Journals Ltd
SLURRY: A STATUS REPORT ROLF
Electric
Power
Research
Institute,
K.
MANFRED
3412 Hillview
Avenue,
Palo Alto, CA 94303, U.S.A.
Abstract-During the years of oil shortage and rapidly increasing oil prices, the need to decrease dependence on oil-fired utility boilers became an urgent concern. The alternatives were to: (1) build new coal-fired stations; (2) modify oil-fired boilers to fire pulverized coal; (3) modify oil-fired boilers to fire coal slurry; (4) modify boilers to fire deeply cleaned, finely pulverized coal; or (5) fire coalderived liquids. Of these alternatives, the use of the coal-water slurry (CWS) promised a combination of advantages: near-term readiness, low-fuel costs compared to oil, moderate conversion costs, and low technical/economic risks. The development work sponsored and peformed since 1979 with coal-water slurries (70 wt % coal, 29 wt % water, 1 wt % additives) has confirmed these expectations. Fuel quality guidelines and test standards have been established, production of CWS in 40,000150,OOOton/yr pilot plants has been demonstrated, utility-scale burner systems (100 MBtu/hr) have been demonstrated, and the effects and costs of modifying typical utility boilers have been predicted. Limited field handling, storage, and use tests were completed successfully. The remaining hurdles to commercial acceptance, such as the establishment of slurry quality control procedures and confirmation of predicted boiler performance as well as conversion economics, can best be resolved by conducting a test in a utility boiler.
BACKGROUND
coal-water slurry (CWS) has been developed in recent years as a way to increase the efficient use of coal. The two main types of coal-water slurries are those developed for long-distance transportation (CWST) and those that can be fired directly as a fuel (CWSF). Both types of coal slurries have developed to the point of commercial readiness. The transportation slurry concept is used at the Salt River Project, the Nevada Power Company, and the Los Angeles Department of Water and Power and Southern California Edison’s Mojave Station where CWST with about 50% coal and 50% water is transported by pipeline for several hundred miles from the mine to the power station. After partial dewatering, the coal is pulverized and fired. The coal-water slurry that can be fired as a fuel contains about 70 wt % water, and 1 wt % additives and can be fired directly almost as if it were heavy fuel oil. The development of CWSF has progressed rapidly and the technology is ready for widespread commercial use.l,’ Both of these slurry types, as well as their variations and derivatives (Table l), were developed to reduce U.S. dependence on foreign fuels and to reduce fuel costs-in the case of the pipeline slurry through lower transportation costs and in the case of the slurry fuel by substitution for more expensive oil. The pace of commercial growth of both types of coal slurries has been disappointing, however, to those of us who have been committed to their development. The issues delaying the further deployment of transportation pipelines are complex, due to political and competitive factors, and will be discussed in detail by other speakers at this conference. Most of my remarks will concern the future of coalwater slurry fuel whose deployment has been slowed by the perceived changes in oil availability, by reduction in oil consumption, and by dropping oil prices. As a result, the current price differential in favor of CWSF is not large enough to motivate potential users to switch. In addition, the perceived risk of changing from an “old” to a “new” fuel and the uncertainty of future energy scenarios make it difficult for processors who must scale up production from existing pilot plants to production plants to raise venture capital and the resulting chicken-and-egg problem between slurry processor and slurry user continues to hinder market growth. Despite the present plateau in the commercial growth of CWSF, however, the future still holds considerable promise. The market will grow if one or a combination of five scenarios occurs (Table 2). I will consider these scenarios individually in the following sections. The
1157
1158
ROLF K. MANFRED Table 1. Types of coal-water
slurries and their uses, benefits, and applications
Coal-water Description
Use
Main benefit
Application
50% coal/50% water
Pipeline transportation
Lower transportation
cost
Old and new coal-design boilers
70% coa1/29% water/l % additives
Direct fired fuel
Costs less than No. 6 oil
Old oil-design boilers
60% coal/40% water. Direct-fired fuel
Pipeline transportation; dewatering (no additives)
Cheaper process (no dewatering; no additives)
Old and new coal-design boilers
Ultraline coal slurry
Direct fired fuel
Reduced derating
Oil- and gas-design boilers
Ultraclean coal slurry
Direct fired fuel
Reduced derating
Oil- and gas-design boilers
Coke-water slurry
Direct fired fuel
Cheaper fuel
Marine boilers
Dense lower-rank coal slurry
Direct fired fuel
Cheaper fuel
Gasifws, fluid beds, slagging combustors
Coal/CO, slurry
Pipeline transportation
No water required
Oil and new coal-design boilers
Coal/alcohol slurry
Direct-fired fuel or transportation slurry
Both slurry components are fuels
Old oil-design boilers
Table 2. Scenarios for CWS market improvement, Increases in oil prices Reduction in CWSF costs Reduction in boiler derating Improvement in coal quality Establishment of domestic and export market clusters Reduction in conversion risks
INCREASES
IN OIL
PRICES
Predictions of long-term oil price trends have been notoriously poor. The current price differential between No. 6 oil at about $29/barrel, or $4.6/MBtu, and CWSF, at $3.2/MBtu (delivered to a typical user site), is $1.4/MBtu. If the boiler and plant conversion costs and predicted boiler capacity losses are then taken into account this price differential represents a near breakeven point and the demand for CWSF will be small (Fig. 1). As the price differential increases, the market potential increases. Estimates, based on the capacity, location, age, and configuration of existing utility boilers, show that the utility market could be as large as 40,OOOMWe (Fig. 1). This could include about 15,OOOMWe of coaldesign boilers that now burn oil and cannot convert to pulverized coal. The oil-design boilers consist of configurations that range from “liberal” conventional designs that may not require derating to increasingly “tight” configurations (Fig. 2) that may have to be substantially derated.3 An increase in oil prices may open a utility retrofit market for all or part of this total, depending on the savings for a given site. If one assumes all of the candidate market to be available, this could represent sales of a total of 84 million tons of slurry per year, or 59 million tons of coal per year. If these speculations hold true, then the utility market could be expected to start growing at a faster rate as the price of No. 6 oil rises to about $3l/barrel and is perceived to have bottomed out.
REDUCTION
IN CWSF
COSTS
Another scenario for increasing the rate of market growth for coal-water slurry fuel could be to reduce its delivered cost. When surveyed, CWS processors predict being able to deliver slurry to typical utility user sites for about $3.2/million Btu. This delivered slurry price includes the cost of coal feedstock of about $1.4/million Btu, about $0.6/million Btu for transportation of the coal from mine to a slurry processing site, and $0.3/millionBtu for CWSF transportation to the user site by rail or barge. Differences in quotes are due mostly to differences in coal feedstock quality, the cost of processing, and user site location.
Coal-water
slurry: a status report
Eqwalent
Utility Retrofit Market (MW[e])
4.1 0.9
4.3
4.5
Mt/yr of CWSF
5.1
5.3
1.9 ($/MBtu)
2.1
4.9
4.7
No. 6 oil price ($/MBtu) 1.7 1.5 1.1 1.3 Differential Price (No. 6 OILCWSF)
1159
Assumptions
Fig. 1. Potential
BOX
effect of oil price changes
on CWSF
CLOSE
TYPE
market
COUPLED
growth.
SCREEN
a
CLOSE
COUPLED
CONVENTIONAL
ARCH
TYPE
b a
Burners: a Gas outlet : b Fig. 2. Typical
boiler configurations.
ROLF K. MANFRED
1160
1. Minemouth
2. Process plant at transport
process plant
hub
6
Power plant 3. Across-the-fence
Fig. 3. Transportation
process plant
scenarios
for conveying
4. Long distance
coal to slurry processing
pipeline
site and slurry to user site.
Reduction of the delivered CWSF price would significantly enhance the marketability of slurry. There is leeway in locating the processing plant to minimize transportation and waste disposal costs. (Fig. 3). Therefore, the selection of the most economical means of conveying coal to the slurry processing site and slurry to the user site is one of the most important, and as yet not fully identified, cost reduction areas. Electric Power Research Institute is sponsoring a study with Texas Eastern Corporation to compare rail, barge, and pipeline options.4 Finally, the judicious selection of effective, low-priced additives or reduction of additive concentration levels should be pursued further to reduce slurry costs. REDUCTION
IN BOILER
CAPACITY
LOSSES
AND
IMPROVEMENT
IN COAL
QUALITY
The costs of converting boilers and plants from firing oil to firing CWS have been estimated by various engineering firms at about %lOO-!§300/kW. In addition, however, the reduced capacity (derating) of converted boilers must be considered (Table 3). The range in boiler conversion costs is due mostly to (1) site-specific differences for installation of particulate control systems, (2) the extent of modifications to be made to specific boilers, and (3) boiler size. The modifications are necessary due to the slagging, fouling, and erosion behavior of coal. It is assumed that scrubbers will not be required, that the boilers remain capable of firing oil at nameplate rating, and that life expectancy is not reduced. Most of the conversion costs are unavoidable, but it may be possible to minimize boiler capacity losses by adjusting the slurry quality or effecting boiler use changes (Table 4). Physical and chemical processes for reducing the ash and sulfur concentrations of coal are in development. Several slurry processors have already incorporated coal cleaning steps into their slurry preparation processes. With many different coals, significant reductions in ash (typically to the 4% level) and sulfur level (80% reduction in pyritic sulfur) have been reported with good carbon recovery. The effect of ultrafine grinding of coal in reducing fly ash particle size has been experimentally confirmed by studies sponsored by Northeast Coal Utilization Project and
Coal-water
slurry: a status report
1161
Table 3. Summary of case study units
Firing typeb
Rating oo CWS % of nameplate capacity
Utility
Unit
Capacity (ME,) contiguration”
Boston Edison consumers Power Debnarva Florida Power and light Houston Lightning and Power Mississippi Power Corporation Virginia Electric and Power
Mystic 7 Karn 3 Edge Moore 5
565/CC screen 62O/box 4lO/box
T W W
60/50 70/50 40140
Sanford 4
4OO/CC arch
W
85/85
Sam Bertron 1
180/C
arch
W
75160
waston 3 Yorktown 3
112/conv. 845/CC arch
T T
lOO/lOO 70153
(Slurry A/B3
‘Cow = conventional design; CC screen = close-coupled screen; CC arch = close-coupled arch. bT = tangential firing; W = wall firing. ?&nry A prepared with low-slagging coal and Slurry B with medium-slagging coal.
Table 4. Approaches to minimizing boiler capacity losses Capacity Losses Current
Target
5-15%
>3%
80% < 200 mesh 90%<3OOu
100% < 325 mesh 100% < 175u
Approach Slurry modifications Reduce coal ash content Improve coal slagging/properties Use find coal grinds Improve atomization (reduce droplet size) Boiler modifications Implement more extensive initial boiler modi6cations Switch fuels Decrease tube life expectancy
-
conducted by Stone and Webster with Babcock and Wilcox. It is hoped that fine fly ash (with low carbon content) will result in reduced slagging, fouling, and tube erosion and reduced boiler capacity losses (derating). The beneficial effects of improved atomization have been demonstrated recently by Babcock and Wilcox, under EPRI sponsorship, with a lO@MBtu/hr burner. In this test 99.5% carbon burnout was achieved. The cost and effects of more than currently assumed modifications to boilers or changes in boiler operation tactics are being studied by utilities, engineering firms, and boiler companies.
ESTABLISHMENT
OF
DOMESTIC
AND
EXPORT
MARKET
CLUSTERS
The design and sales management of a slurry processing plant can be made to be costeffective if different market demands can be satisfied from a central location. The resulting economy, of course, cannot occur until such diverse markets exist, but the preparation of plans and estimates is necessary to promote market growth.
REDUCTION
IN
CONVERSION
RISKS
The perception of risk, i.e. the unknowns of fuel dependability and quality control; the unforeseen aspects of daily transportation, handling and storing operations; and the unconfirmed effects on the boiler of combustion, have a retarding effect on market growth. The technology has progressed to the point where a significant demonstration in a sufficiently large, oil-design utility boiler is needed. EPRI, DOE, and private industries have produced the technology for such a demonstration. We are co-operating with our
1162
ROLF K. MANFRED
member utilities, with government agencies, engineering firms, and the transportation demonstration.
and with slurry vendors, boiler companies, industry to initiate and conduct such a
SUMMARY
The current state-of-the-art of coal-water slurry fuel is such that no major technical problems are apparent. The growth of a substantial market is held back by a breakeven cost differential between No. 6 oil and CWSF at present oil prices. Commercialization will also await the performance of a large demonstration test. The present oil to slurry price differential of about $1.4/MBtu must be increased to about $1.7/MBtu before the market starts to grow and must increase to over $2.0/MBtu before full market development can be realized. Approaches to achieve such an increase in price differential can be identified and must be pursued. A significant hurdle will be overcome if sufficient backing can be gathered for a demonstration test in a large boiler. REFERENCES 1. J. P. Dooher, “Coal-Water Slurry Pumping and Flow Tests”, Electric Power Research Institute, Palo Alto, Calif. Rep. G-3722 (1984). 2. R. D. Perkins, “Coal-Water Slurry Test in an Industrial Boiler”, Electric Power Research Institute, Palo Alto, Calif. Rep. CS-4268 (1985). 3. E. Kirnel and R. Kurtzrock, “Comparison of Coal Conversion Alternatives”, in Proceedings ofthe Department of Energy Fifth International Symposium on Coal-Slurry Combustion and Technology, U.S. Department of Energy, Washington, D.C. (1983). 4. 0. Rogers, C. Durbidge and R. Manfred, “Coal-slurry Fuel Transportation Alternatives”, in Proceedings of the Department of Energy Seventh Annual International Symposium on Coal-Slurry Fuels, U.S. Department of Energy, Washington, D.C. (1985).