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Conversion of Coal to Liquid (CTL) Fuels

Title: Coal Cowboy Duration: 00:12:51 Link: http://coe-jaguar.engr.utexas.edu/mediasite/Viewer/?peid=1ed1281cb87e405d93db5389ceb34760. Conversion of Coal to Liquid (CTL) Fuels. Several very old processes… since WWII Same general theme: increase H/C ratio

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Conversion of Coal to Liquid (CTL) Fuels

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  1. Title: Coal CowboyDuration: 00:12:51Link: http://coe-jaguar.engr.utexas.edu/mediasite/Viewer/?peid=1ed1281cb87e405d93db5389ceb34760

  2. Conversion of Coal to Liquid(CTL) Fuels • Several very old processes… since WWII • Same general theme: increase H/C ratio • Can make a wide variety of hydrocarbon products (e.g. synthetic crude or synfuel) • Two basic methods: direct and indirect

  3. Advantages of Coal To Liquid (CTL) Fuels • CTL Improves national and economic security • Lessens dependence on foreign oil • Uses domestic resources and produces more jobs for Americans • Provides environmental benefits - Cleaner fuels that reduce NOx and particulate emissions - Enables use of higher efficiency engines • Is capable of capturing CO2 emissions • Provides geographic diversity as energy source

  4. Coal Liquefaction • Very expensive • Liquefaction attractive for transportation fuel • Indirect liquefaction commercially proven (>50 yrs) • Acid gas removal by amines (CO2, H2S) • S removal by Claus Process H2S + O2 = H2O + SO2 H2S + SO2 = S + H2O

  5. Direct Liquefaction of Coal Attractive Because of • Low transportation cost • Less chemical transformation required • Higher efficiency than high Btu gas production • Easy to store • Less water required for manufacture However, processing slurries at high temperature and pressure presents difficulties with equipment life and solid/liquid separation (still not commercial)

  6. SASOL in South Africa Indirect Coal liquefaction is proven technology • South Africa’s SASOL Co. developed a commercial coal liquids industry (fuel plus chemicals) • The plant produces about 150,000 barrels daily at its second plant

  7. Coal To Liquids in China Concerned about increasing dependence on oil imports and its impact on economic growth and national security, China is making a massive $6 billion investment in new coal liquefaction plants. Planned $2 billion Shenhua facility will eventually produce 50,000 barrels daily of diesel fuel and gasoline.

  8. Two Basic Approaches To Convert Coal To A Liquid Fuel 1. Direct Liquefaction: • Dissolves coal in a solvent at elevated temperature and pressure • Combined with hydrogen gas and a catalyst 2. Indirect Liquefaction: • Involves first gasifying coal, followed by reacting carbon monoxide and hydrogen together nCO + (2n+1)H2 = CnH2n+2 + nH2O

  9. Comparison of Processes DIRECT LIQUEFACTION INDIRECT LIQUEFACTION • Adds hydrogen to break down the coal • Dissolves in a solvent followed by hydrocracking • Operates at 450 C and 170 bars • Light products are distilled • Medium and heavy distillates obtained from vacuum distillation • Liquid yields of 70% of the dry weight of coal feed • Further upgrade is needed for use as transportation fuels • Complete breakdown of coal with steam and oxygen • Sulfur is removed from the syngas • Syngas reacted over catalyst at 300 C and 20 bars • Produces a lighter suite of products; high quality gasoline and petrochemicals • Oxygenated chemicals

  10. Indirect Liquefaction • Fischer-Tropsch Indirect Liquefaction Process - Yields high quality transportation fuels plus other products

  11. Schematic diagram of different coal liquefaction processes.

  12. CTL Costs • Coal-based liquid fuel becomes viable when the per-barrel price of oil is expected to exceed the $70-100 range for 20+ years • CTL has high front-end capital cost - A 50,000 barrel-a-day plant would cost over $3 billion to construct • The product refinement process is three to four times more expensive than refining an equivalent amount of oil • The cost of sequestering the captured CO2 would increase the price of the end product by $10-20 a barrel. • The imposition of a carbon cap and trade policy would also raise the cost of fuel produced with CTL technology

  13. CTL is Very Water-Intensive • CTL requires ~7:1 water to fuel ratio • ~7 gallons of water per gallon of fuel produced • Water scarcity can be a limiting factor for CTL plant permitting • Conventional gasoline • 1-2.5 gallons of water per gallon of fuel produced • Irrigated Biofuels • 1000 gallons of water per gallon of fuel

  14. Liquids Fuels Summary…. • Proven technologies • All processes require adding hydrogen • All processes remove sulfur and ash • Product include liquid, gas, and combustible solid(char) • Several long-standing commercial processes (e.g., S. Africa - SASOL) • So far no large-scale use without government support

  15. Coal to Liquids Summary…. • Good promise because of very large coal deposits in the world • Numerous processes that can generate a wide variety of products • Environmental issues include some hazardous wastes and byproducts • Does not yet effectively compete with natural gas or oil production … requires some form of subsidy

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