by clicking the arrows at the side of the page, or by using the toolbar.
by clicking anywhere on the page.
by dragging the page around when zoomed in.
by clicking anywhere on the page when zoomed in.
web sites or send emails by clicking on hyperlinks.
Email this page to a friend
Search this issue
Index - jump to page or section
Archive - view past issues
FLEXO Magazine : October 2011
The following emission factors for gasoline and diesel engines are based on 99 percent conversion of fuel carbon content to CO2. Source: Table 1.3 -12. U.S. Environmental Pro- tection Agency AP-42, 1 .3 Fuel Oil Combustion www.epa.gov/ ttnchie1/ap42/ch01/final/c01s03.pdf Gasoline Diesel 1.08 lb/hp-hr 1.15 lb/hp-hr 154 lb/MMBtu 164 lb/MMBtu Fuel Oil CO2, CH4, and N2O emissions are all produced during fuel oil combustion. Nearly all of the fuel carbon (99 percent) in fuel oil is converted to CO2 during the combustion process. This conver- sion is relatively independent of firing configuration. Although the formation of CO acts to reduce CO2 emissions, the amount of CO produced is insignificant compared to the amount of CO2 produced. The majority of the fuel carbon not converted to CO2 is due to incomplete combustion in the fuel stream. Formation of N2O during the combustion process is gov- erned by a complex series of reactions and its formation is dependent upon many factors. Formation of N2O is minimized when combustion temperatures are kept high (above 1475̊F) and excess air is kept to a minimum (less than 1 percent). Additional sampling and research is needed to fully charac- terize N2O emissions and to understand the N2O formation mechanism. Emissions can vary widely from unit to unit, or even from the same unit at different operating conditions. Average emission factors based on reported test data have been developed for conventional oil combustion systems. CH4 emissions vary with the type of fuel and firing configu- ration, but are highest during periods of incomplete combus- tion or low-temperature combustion, such as the start-up or shut-down cycle for oil-fired boilers. Typically, conditions that favor formation of N2O also favor emissions of CH4. Table 2. Default CO2 emission factors from liquid fuels based on 99 percent conversion of fuel carbon content to CO2. Source: Table 1.3 -12 . U.S. Environmental Protection Agency AP-42 , 1.3 Fuel Oil Combustion www.epa.gov/ttnchie1/ap42/ch01/final/c01s03.pdf Fuel Type Carbon (percent) Density (lb/gal) Emission Factor (lb/103 gal) No. 1 Kerosene 86.25 6.88 21,500 No. 2 87.25 7.05 22,300 Low Sulfur No. 6 87.26 7.88 25,000 High Sulfur No. 6 85.14 7.88 24,400 lb/gal x 0.12 = gram/cm3 lb/103 gal x 0.12 = kg/m3 Usage (gal) x Emission factor (lb /103 gal) = CO2 (lbs) CO2 (lbs) / 2,204.62 lbs/metric tons = CO2 (metric tons) Example: If a facility burns 5,000 gal of No. 2 fuel oil in its boiler, then 5,000 gal x 22,300 lb/103 gal = 111,500 lbs 111,500 lbs / 2,204.62 lbs/metric ton = 50.58 metric tons CO2 NaTural Gas Emissions from natural gas-fired boilers, furnaces and oxidizers include nitrogen oxides (NOx), carbon monoxide (CO), and carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), volatile organic compounds (VOCs), trace amounts of sulfur dioxide (SO2), and particulate matter (PM). Natural gas is mainly methane (CH4) which is the simplest of the hydrocarbons. Even though natural gas is cleaner than oil, gasoline or coal, it does convert to CO2 when burned. In the combustion process, almost all of the carbon in the natural gas converts to CO2 as combustion adds oxygen to the methane. Due to impurities present during the natural gas refining process, traces of sulfur, nitrogen and other hydrocar- bons are also emitted when natural gas is burned. To calculate the amount of CO2 emitted from natural gas combustion, determine how much was used in CCF (cubic feet). Natural gas combustion yields 12.012 lbs of CO2 per 100 CCF. Multiply 12.012 lbs by the number of CCF consumed an- nually and divide by 2,204.62 to get metric tons of CO2. (Source: US Department of Energy 1605(b) Voluntary Reporting of Greenhouse Gases Program www.eia.gov/ oiaf/1605/coefficients.html) Usage (CCF) x (12.012 lbs CO2/CCF) / 2,204.62 lbs/metric ton = CO2 emissions (metric ton) Example: A boiler uses 12,424 CCF of natural gas. 12,424 CCF x (12.012 lbs CO2/CCF) / 2,204.62 lbs/metric ton = 67.69 metric tons CO2 PrOPaNe Propane itself is not a direct GHG when released into the air. Unlike fuels such as natural gas, propane vapor is remo- ved from the atmosphere faster than it takes for it to become well-mixed and impact the global climate. In addition to propane-fired boilers, more than 600,000 pro- pane forklifts operate in factories and warehouses across the United States. Although they have less GHG emissions than gas or diesel powered counterparts, when propane is used as a fuel, it does generate small amounts of GHGs. Propane does emit CO2 and much lesser amounts of N2O and CH4 . Table 3. Emission factors for sources using propane. Sources: The Conservation Fund www.conservationfund.org/gozero/metrics_ and_calculations; U.S. Environmental Protection Agency AP-42 , 1 .5 Liquefied Petroleum Gas Combustion www.epa.gov/ttnchie1/ap42/ ch01/final/c01s05.pdf; and U.S. Environmental Protection Agency, Sector Strategies. 2009. Potential for Reducing Greenhous Gas Emissions in the Construction Sector. www.epa.gov/sectors/pdf/ construction-sector-report.pdf Combustion Source Emission Factor (lb CO2 /gal propane) Boilers 12.40 - 12 .50 Forklifts 12.70 Fueled Vehicles The U.S . Enegy Information Administration (U.S . EIA) provides extensive details on the amount of N2O and CH4 emitted from vechiles based on the type of vehicle and fuel; and the model year (http://www.eia.gov/oiaf/1605/coefficients. 92 FLEXO OCTObER 2011 www.flexography.org