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Landfill Gas Utilization

Landfill Gas Utilization. Hayley Eberly Department of Chemical Engineering The University of Texas at Austin. C, 2007 BASF, 2007. Agenda. Landfill Gas Overview Environmental Effects of Landfill Gas Life of Landfill Gas Landfill Gas Utilization Technological Changes Potential Problems

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Landfill Gas Utilization

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  1. Landfill Gas Utilization Hayley Eberly Department of Chemical Engineering The University of Texas at Austin C, 2007 BASF, 2007

  2. Agenda • Landfill Gas Overview • Environmental Effects of Landfill Gas • Life of Landfill Gas • Landfill Gas Utilization • Technological Changes • Potential Problems • Questions • Flare Image, n.d.

  3. Landfill Gas (LFG) Overview • 1 million tons of waste produces 432,000 ft3/day of LFG • Produced by • Bacterial decomposition • Volatilization • Chemical reactions • Composed of different gases • Heating value of 500 BTU/SCF • Half the heating value of natural gas Landfill Gas Composition Edgar, n.d. • Landfill Gas Primer, n.d.

  4. Environmental Effects • Landfills are the 2nd largest human source of methane • Represent 23 % of all methane produced • Methane absorbs 20X more infrared radiation by weight than CO2 • LFG releases carbon dioxide • Landfill gas also contains… • Volatile organic compounds (VOC) • Contribute to ozone formation • Hazardous air pollutants (HAP) • Affect human health when exposed Frequently Asked Questions, 2008

  5. Life of Landfill Gas Landfill gas is piped to a plant and partially displaces natural gas usage. The waste decomposes and produces landfill gas. Trash is delivered to landfill. • Methane Generated From, 2008

  6. Landfill Gas Utilization • Cheaper than natural gas • Refineries and petrochemical plants account for 14% of the natural gas used as fuel by industry in the U.S. • Significantly reduces the amount of carbon dioxide and methane released into the atmosphere by landfills • Can reduce NOx emissions when mixed with methane • No equipment changes downstream from burner Schematic of LFG System • Edgar, n.d. • Landfill Gas Direct, 2005

  7. Technological Changes • Install separate fuel train and gas spuds for LFG • Dual fuel - fed by separate gas lines that connect at an intake flow regulator valve • Larger valve openings for higher volumetric flow • Maintain natural gas fuel train and gas ring • Replace internal parts with corrosion-resistant materials • Treat LFG before entering boilerto avoid condensation and corrosion Schematic of a Natural Gas Co-fired Boiler Edgar, n.d. Uses in Industry, 2004

  8. Potential Problems • Adiabatic flame temperature (AFT) • Natural gas – 2300 K • Landfill gas – 2100 K • 50/50 mixture – 2200 K • Flame stability and burning velocity • With good mixing in the combustor, LFG has comparable stability to methane • Install UV sensors • Stable zone of combustion • Smaller for LFG than methane • Must ensure constant heating value or mix with methane • Corrosion • Use corrosion-resistant materials • Maintain temperature above dew point of corrosive materials • Preheat combustion air • Insulate the stack Edgar, n.d.

  9. References • BASF. (2007). Retrieved November 22, 2008, from Linde Engineering Web site:http://www.linde-india.com/customerreference/FrmPlantDetail.aspx?CatId=11&&Iid=5 • C, C. M. (2007, October 30). The Macho Response. Message posted to http://themachoresponse.blogspot.com/2007/10/bully-for-you.h • Edgar, T. F. (n.d.). Evaluation of Environmental Emissions for Combustion of Landfill Gas in a Texas Petrochemical Plant. Retrieved from University of Texas Web site: http://texasiof.ces.utexas.edu/PDF/Reports/FINAL%208%2019%20Landfill%20Gas %20Feasiblity%20Analysis.pdf • Frequently Asked Questions About Landfill Gas and How It Affects Public Health, Safety, and the Environment. (2008, July 2). Retrieved November 23, 2008, from U.S. Environmental Protection Agency Web site: http://www.epa.gov/lmop/ faq-3.htm • Landfill Gas Primer - An Overview for Environmental Health Professionals [U.S. Department of Health and Human Services]. (n.d.). Retrieved November 23, 2008, from http://www.atsdr.cdc.gov/hac/landfill/html/ch2.htm • An Overview of Landfill Gas Energy in the United States. (2008, June). Retrieved November 18, 2008, from U.S. Environmental Protection Agency Web site: http://www.epa.gov/lmop/docs/overview.pdf • Flare Image. (n.d.). Retrieved November 24, 2008, from State Energy Conservation Office Web site: http:// www.seco.cpa.state.tx.us/re_biomass-urban.htm • Methane generated from Sioux Falls Regional Landfill to provide energy for POET ethanol plant. (2008). Retrieved November 23, 2008, from POET Web site: http://www.poet.com/news/showRelease.asp?id=115 • Landfill Gas Direct Use. (2005, May 6). Retrieved November 24, 2008, from U.S. Environmental Protection Agency Web site: http://www.epa.gov/stateply/documents/events/may2005/hildreth0505.pdf • Uses in Industry. (2004). Retrieved November 24, 2008, from http://www.naturalgas.org/overview/uses_industry.asp

  10. Questions

  11. Additional Slides

  12. Modern Sanitary Landfill • An Overview of Landfill, 2008

  13. Production phases of typical landfill gas

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