Fuels to Drive Our Future (1990) / Chapter Skim
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4. Conversion Technologies and R&D Opportunities
4. Conversion Technologies and R&D Opportunities
Pages 57-104
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From page 57... ...
The following sections address the individual conversion technologies. PRODUCTION OF HYDROGEN AND SYNTHESIS GAS Production of hydrogen and synthesis gas (syngas)
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From page 58... ...
Since this is also the range of equivalent crude prices where use of coal liquefaction and shale oil are competitive, attention to reducing the cost of production of hydrogen and syngas from coal is important. Table 4-1 shows the amount of hydrogen consumed for conversion of Illinois No.
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From page 59... ...
s9 ts ~ ~ Q ,, Ct CJ)
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From page 60... ...
In the second case heat is added to the hot solids or gas in a separate vessel via combustion with air. The reaction of coal with steam produces, in addition to carbon monoxide and hydrogen, carbon dioxide (CO2)
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From page 61... ...
While multiple units are needed to allow for periodic repair of ceramic liners, it appears that much larger units may offer opportunity for cost savings for a scale of operation consistent with the scale needed for producing transportation fuels. While these commercial systems could probably be increased in size, other systems may be more amenable to major scale-up and integration with the coal liquefaction process.
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From page 62... ...
. J Tar Flue ' Gas , ~ 'Combustion Hot Solids aim//////; Hot Solids Coal Limestone Air Steam Gas Gasification l ~ Waste 1 Solids FIGURE 4-2 Schematic of a coal gasification process following pyrolysis and combustion to obtain higher thermal efficiencies.
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From page 63... ...
Estimated costs, using the test results, indicated a substantial reduction in synthesis gas cost (Schulman and Biasca, 1989) (see Appendix D, Table D-3.
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From page 64... ...
As described in the 1990 proposed program, the program is aimed at directly TABLE 4-2 The 1988 and 1989 Appropriations for Work Relevant to Coal Gasification Appropriations ($1000s) 1988 1989 Relevance to Liquid Fuel Production from Coal Advanced research 2,698 2,679 High Systems for synthesis gas production 1,958 2,679 High Systems for coproducts production 5,292 9,084 Medium Total 9,948 14~442 Underground coal gasification 2,777 1,371 High Systems for power production 11,176 5,926 Low Systems for industrial fuel gas 1,369 848 Medium Great plains coal gasification (methane production)
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From page 65... ...
Conclusions and Recommendations Manufacturing of hydrogen and synthesis gas is a major economic and energy cost and source of CO2 in the production of liquid transportation fuels from natural gas and coal, shale, heavy oils, and biomass. Processes for syngas manufacturefrom natural gas are widely used and of continuing R&D interest to industry.
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From page 66... ...
While general-purpose coal gasification processes are now in limited commercial use, it is believed that important opportunities exist for development of gasification processes specifically chosen for integration with direct coal liquefaction to reduce both cost and CO2 production. Such an optimized process might incorporate features such as coproduction of pyrolysis liquids and low-cost methane, larger-scale equipment, and use of air combustion, biomass combustion, or possibly nuclear heat in the long run.
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From page 67... ...
Fuel Properties The product qualities resulting from the various heavy oil upgrading technologies are quite variable and are strongly dependent on feed type, process type, and processing conditions. However, producing fuels of acceptable properties is possible (in all cases)
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From page 68... ...
Many refineries are already equipped to convert heavy oils and residue to transportation fuels. However, most refineries use coking processes rather than the more expensive hydroprocessing technologies.
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From page 69... ...
There is already an extensive commitment to R&D in this area in the private sector, and much duplication would likely result. TAR SANDS RECOVERY AND PROCESSING Tar sands are defined as "any unconsolidated rock containing a crude oil which is too viscous at natural reservoir temperatures to be commercially producible by primary recovery techniques"; American Petroleum Institute gravities are generally less than 10° (IOCC, 1982; see also Appendix C)
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From page 70... ...
Porosity, a characteristic of the host rock, ranges from 15 to 40 percent of total rock weight, and oil saturation usually represents about 50 percent of the porosity. Overburden, which varies by site, is an important determinant of the total cost of tar sands recovery, as is the extent of layering of a given deposit, and bitumen properties also vary widely among different deposits.
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From page 71... ...
Extraction Depending on the type of tar sand material, either a water-based or hydrocarbon solvent is needed to recover tar sand bitumen from host rock. The Clark hot-water process, using a caustic water solution to emulsify oil from the tar sand particles, is effective for Canadian tar sands because the sand particles are wetted with water and surrounded by bitumen.
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From page 72... ...
Solvent Tar Sands ~Recycle Solvent Water r Recycle Solvent l 11 1 Fines Solvent Extraction ~ Removal ~ Recovery Tailings Fines Bitumen FIGURE 4-3 Hydrocarbon solvent extraction process.
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From page 73... ...
When using the process with tar sands, the feed is mixed with hot combusted spent sand in a screw conveyor and added to the retorting reactor, which operates at 480° to 510°C (900° to 950°F) (Figure 4-4~.
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From page 74... ...
Since sulfur is more easily removed than nitrogen in hydrotreating, the sulfur content of upgraded products from Utah or other low-sulfur tar sands will be very low. Environmental Considerations Tar sands processing converts part of the bitumen to coke and fuel gas, which are burned in processing plants and refineries to generate steam and power.
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From page 75... ...
tar sands processing could improve its overall economics. These opportunities include improved bitumen upgrading; higher bitumen recovery, which would require less mining; improvements in solids removal, which could amount to 15 percent of the total cost of products depending on mineral characteristics; and improved techniques that permit more selective mining of the richest ore, which would reduce both processing and mining costs.
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From page 76... ...
The current DOE program for surface extraction of tar sands is focused on the Western Research Institute (WRI) bitumen recycle process and optimization of a few alternative recovery processes.
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From page 77... ...
This layer of oil shale, averaging 30 gaVton' contains approximately 50 billion bbl of shale oil (Lewis, 1980~. This layer is suitable for room and pillar mining but generally not open pit mining because of the high ratio of overburden to oil shale.
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From page 78... ...
Mining and Disposal To a great extent mining technology is transferrable to oil shale. The scale of the operation is large, however, and there are opportunities for improvements.
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From page 79... ...
Retorting Different retorting processes have evolved from different methods for heating solid particles of oil shale. Either hot gas or hot solid material may be used to supply heat to the shale.
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From page 80... ...
Appendix F contains a brief description of several hot gas and hot solid retorting processes. Upgrading The properties of shale oil vary as a function of the retorting process.
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From page 81... ...
Virtually all proposed advanced oil shale retorting systems use hot recycled shale as the heat carrier, providing rapid mixing with raw shale, rapid heating, and a subsequent soak time of 1 to 2 min for pyrolysis to occur. This process greatly increases throughput and reduces costs, compared to hot gas processes.
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From page 82... ...
Pyrite forms hydrogen sulfide in the pyrolyzer in both hot gas and hot solid retorts. However, Fe2O3 in recycled shale scavenges hydrogen sulfide (H2S)
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From page 83... ...
The endogenous price calculation in Chapter 3 for oil shale indicates a price of about $43/barrel of crude oil equivalent. Potential cost reductions in the major categories involved in oil shale production and conversion are given in Table 4-6, not including those accruing from making it possible to transport shale oil to a refinery by pipeline without upgrading.
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From page 84... ...
These results, coupled with the possible cost reductions in Table 4-6, indicate that a cost target of $30/barrel or less is possible with development of advanced technology. Recommendations for DOE Research Program for Oil Shale Development The annual DOE program in oil shale is about $10.53 million for fiscal year 1989 with both eastern and western oil shale included.
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From page 85... ...
More work is needed to understand the fundamental chemistry of oil shale retorting, especially specific reactions and kinetics, to solve problems and reduce costs. Additional work is needed in pyrolysis and combustion chemistry to better design and optimize the retorting process and equipment.
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From page 86... ...
In the longer term a method of underground mining, perhaps some kind of block caving, should be developed to recover a large fraction of the oil shale in the north-central part of the Piceance basin that is too deep for open pit mining. Research on groundwater contamination by mining also is important.
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From page 87... ...
and surface retorting technology takes the same amount of time, with the critical path being surface retorting. Based on the scenarios presented in Chapter 1, the cost of crude oil could exceed $30/barrel before an advanced oil shale technology is demonstrated.
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From page 88... ...
The Advanced Mitsubishi Synthesis Gas to Gasoline process has been demonstrated at the pilot plant scale (1 bbl/day)
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From page 89... ...
A commercial-scale test of the MOOD process was successfully conducted at a Mobil refinery in late 1981 using feedstock from an FCC unit. Methanol for Electricity Generation Coal gasification is currently being developed to generate syngas for power generation.
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From page 90... ...
Syngas-based fuels from natural gas are expensive because of the high value of domestic natural gas for conventional markets. For example, natural gas at $5/million Btu represents $33/barrel of the $60/barrel cost of MTG gasoline using the fluid bed reactor design.
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From page 91... ...
, the cost of methanol from coal would be reduced by $4/barrel oil equivalent due to improved synthesis gas unit designs. Using western coal in a fluid bed gasifier would reduce the cost of methanol by an additional $6/barrel.
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From page 92... ...
DIRECT COAL LIQUEFACTION U.S. recoverable coal reserves are large, representing a significant proportion of world energy resources, and their prices are likely to remain modest (EIA, 1989a,b; Table 1-2; Table D-2.
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From page 93... ...
Few of the smaller pilot plants survived; today the only integrated pilot plant operating full time on direct coal liquefaction is the Advanced Coal Liquefaction R&D Facility in Wilsonville, Alabama. Test units are available for contract at Hydrocarbon Research, Inc., Lummus-Crest, and the University of Kentucky, and Amoco Oil Company has smaller bench-scale pilot plants in operation.
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From page 94... ...
All of these projects are government funded. Fuel Properties Products of direct coal liquefaction are expected to meet all current specifications for transportation fuels derived from petroleum.
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From page 95... ...
Capital investment at Wilsonville is needed to adapt these technologies and determine their economic attractiveness. There are clearly many opportunities to improve the economics of direct coal liquefaction.
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From page 96... ...
The DOE-funded programs that are relevant to the conversion of coal into transportation fuels in fiscal year 1990 allocate approximately twice as much money to process development as to each of the other categories (see Appendix G for definitions of fundamental, exploratory and catalyst, and process research)
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From page 97... ...
The Research, Development, and Demonstration organization of the International Energy Agency might coordinate and monitor the project. A successful commercial-scale demonstration would be valuable for the United States should it become desirable for the supply of liquid transportation fuels to be augmented through direct coal liquefaction technology.
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From page 98... ...
It was used as a coal liquefaction pilot plant until 1986 and thereafter processed petroleum vacuum reside. Although not used for coprocessing, its operation with both coal and petroleum resid indicates the flexibility of the technology to accommodate different feedstocks.
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From page 99... ...
Fuel Properties Coprocessing is similar to direct coal liquefaction in that it produces fuels that are compatible with existing fuel markets. In particular, it is directed toward producing transportation fuels because these are the highest value-added products.
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From page 100... ...
Recommendation for the DOE Program Coprocessing of heavy oils or residuum with coal may offer an opportunity for the introduction of coal as a refinery feedstock. A demonstration plant for production of a clean boiler fuel is part of the DOE's clean coal technology program.
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From page 101... ...
Pyrolysis liquids require extensive hydrogenation to be useful as transportation fuels. Another approach is to combine coal pyrolysis with production of synthesis gas to potentially increase the liquid yields for conversion processes producing transporation fuels.
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From page 102... ...
Technology and State of Development Numerous direct methane-to-methanol conversion routes are being studied at the bench scale by various companies, government agencies, and universities. These include cold flame oxidation (direct partial oxidation)
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From page 103... ...
Gulf Coast (California Fuel Methanol Study, 1989~. Even if liquid fuels from natural gas were to become viable owing to a combination of cost reductions and special situations, exploitation would use foreign natural gas.
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From page 104... ...
Even if liquid fuels from natural gas were to become viable owing to a combination of cost reductions and special situations, exploitation would use less valuable foreign natural gas in a remote location. Therefore, government-sponsored research on direct methane conversion technology should be limited to fundamental research.
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