Coal Energy for the Future (1995) / Chapter Skim
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9 ADVANCED RESEARCH PROGRAMS
9 ADVANCED RESEARCH PROGRAMS
Pages 160-178
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From page 160... ...
The specific research opportunities discussed were identified by the committee on the basis of its review and analysis of current DOE programs (chapters 5 through 7) , and particular importance was accorded activities unique to coal technologies.
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From page 161... ...
A more detailed comparison between the FY 1994 enacted appropriation and the 1995 congressional request is shown in Table 9-2, which also shows in more detail the advanced research activities funded under AR&TD and AR&ET. Major budget reductions are proposed in FY 1995 for the programs in materials (25 percent)
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From page 162... ...
. The role of advanced research within the FE program is "to stimulate, nurture, and advance critical enabling science and technologies for fossil energy systems." A series of advanced research goals, strategies, and success indicators have been selected to support relevant DOE business lines and the core Office of FE business lines of clean fuel systems and clean/efficient power systems (see Chapter 2)
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From page 163... ...
The optimum role for DOE differs from one advanced research area to another but is largely determined by technology needs and their degree of specificity to coal-based systems and by complementary research activities in industry and government organizations outside DOE. The following discussions of some major research areas address opportunities for DOE advanced research programs to contribute to the development of coal technologies.
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From page 164... ...
In contrast, the understanding and quantitative treatment of carbon kinetics, taking into account catalytic and physical interactions with ash and graphitization of carbon as the oxidation process proceeds, is at a relatively primitive stage. Since future innovations in coal gasifies and combustor design will depend, to a considerable extent, on quantitative understanding of the interaction between pyrolysis, carbon oxidation, and emissions, the committee noted that DOE's advanced research program for coal needs to address this issue.
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From page 165... ...
In reviewing current DOE coal advanced research programs, the committee particularly noted the decline in efforts devoted to coal liquefaction technology. Given the likely growth in importance of coal liquids in the mid and long term, as described in the committee's strategic planning scenarios (see Chapter 4)
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From page 166... ...
For direct liquefaction, existing processes require cold gas cleanup, shifting to convert carbon monoxide and water to hydrogen and CO2, and scrubbing to remove CO2. There would be significant energy and capital cost savings if the hot gasifies gas could be used without cooling and further processing.
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From page 167... ...
Three areas have been selected for emphasis and are discussed below: advanced gas turbines; hightemperature, high-pressure heat exchangers; and inorganic membranes. The present discussion is not intended to provide an exhaustive list of materials research opportunities relevant to the coal program but rather to highlight key materials-based enabling technologies critical to the success of DOE programs in advanced clean fuels and advanced power systems.
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From page 168... ...
In the case of gasification-based systems, the environmental constraints imposed on the turbine materials are less demanding than in the case of direct coal firing but more severe than in a natural-gas-fired system. Coal gasification produces a raw syngas consisting mainly of carbon monoxide and hydrogen but with substantial quantities of CO2 and water; minor quantities of hydrogen sulfide, ammonia, and hydrogen chloride; and a few parts per million of alkali metals (NRC, 1986~.
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From page 169... ...
Heat Exchangers In terms of materials behavior, the critical requirements for the ceramic heat exchanger for EFCC power generation systems (see Chapter 7) are · to maximize operating temperatures for the proposed duty cycle, notably combinations of high temperature and pressure; · to resist fouling and alkali corrosion, with emphasis on the latter for lowrank coals; and · to avoid catastrophic failure.
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From page 170... ...
Subsequent testing with a coal-fired combustor will verify the ability of the slag screen to protect the ceramic heat exchanger from coal ash. Ceramic materials demonstrate superior corrosion resistance compared to conventional metals and superalloys but can be severely degraded by alkali metals in coal combustion products.
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From page 171... ...
A particularly important application for advanced clean/ efficient power systems is the cleanup of coal gasification streams to drive advanced turbines. As discussed above, the ability of hot gas cleanup systems to reduce the contaminants to levels acceptable for high-temperature advanced turbines remains to be demonstrated.
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From page 172... ...
Ceramic membranes consist of a porous support a few millimeters thick, a porous intermediate layer 10 to 100 microns thick with pore diameters in the range of 0.05 to 0.5 microns,2 and the separation layer with a thickness of 1 to 5 microns (Burggraaf et al., 1989~. Generally, the separation layer must have pore diameters less than 10 rim for effective separation of gaseous components by diffusion (Krishnan et al., 19931; in some cases a mean pore size of 2.5 nm may be necessary.3 Current commercially available membranes do not meet all performance requirements for cleanup of coal-gas and flue gas streams, although several manufacturers produce inorganic membranes for micro- and ultrafiltration applications, and some of these have pore diameters less than 10 rim and are capable of separating gaseous components.
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From page 173... ...
Inorganic membranes with high separation efficiencies and long-term resistance to high-temperature corrosive environments have the potential to improve the economics of power generation from coal, particularly for systems using advanced turbines. Materials development is required to improve the separation efficiency of ceramic membranes used for hot gas and flue gas cleanup.
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From page 174... ...
Paper presented at the Joint Contractors Review Meeting, FE/EE Advanced Turbine Systems Conference, FE Fuel Cells and Coal-Fired Heat Engines Conference, U.S. Department of Energy, Morgantown Energy Technology Center, Morgantown, West Virginia, August 3-5.
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From page 175... ...
Paper presented at the Meeting of the International Gas Turbine Institute, Cincinnati Ohio, May 24-25.
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From page 177... ...
^Q III RccommeDd~hons ~r DUF,s Future Coat Program
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