Presentation on theme: "Landfill Gas Utilization Hayley Eberly Department of Chemical Engineering The University of Texas at Austin C, 2007 BASF, 2007."— Presentation transcript:
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 Questions Flare Image, n.d.
Landfill Gas Composition Landfill Gas (LFG) Overview 1 million tons of waste produces 432,000 ft 3 /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 Edgar, n.d. Landfill Gas Primer, n.d.
Environmental Effects Landfills are the 2 nd largest human source of methane Represent 23 % of all methane produced Methane absorbs 20X more infrared radiation by weight than CO 2 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
Landfill gas is piped to a plant and partially displaces natural gas usage. Life of Landfill Gas Methane Generated From, 2008 Trash is delivered to landfill. The waste decomposes and produces landfill gas.
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 NO x emissions when mixed with methane No equipment changes downstream from burner Edgar, n.d. Landfill Gas Direct, 2005 Schematic of LFG System
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 boiler to avoid condensation and corrosion Edgar, n.d. Uses in Industry, 2004 Schematic of a Natural Gas Co-fired Boiler
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.
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