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Pulverized Coal Power Plant

Pulverized Coal Power Plant. Environmental Considerations. Early Air Pollution in England. In 1306, to clean up London's air, King Edward I, outlawed coal burning exclaiming "…whosoever shall be found guilty of burning coal shall suffer the loss of his head.".

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Pulverized Coal Power Plant

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  1. Pulverized Coal Power Plant Environmental Considerations

  2. Early Air Pollution in England In 1306, to clean up London's air, King Edward I, outlawed coal burning exclaiming "…whosoever shall be found guilty of burning coal shall suffer the loss of his head." After deforestation, rather than freeze and starve, people began burning c0al again. In 1590, Queen Elizabeth bans burning coal again, without the death penalty

  3. Addressing Pollutants • 1930’s: soot and smoke (dirtied cities) • Taller stacks • 1960’s: partial combustion products, fly ash • Precipitators, scrubbers • 1980’s: SOx • Scrubbers, low sulfur coal • 1990’s: NOx, • Low NOx burners, over-fire air, gas recirculation • 2000: Mercury • Scrubbers, Activated Carbon Injection (ACI) • 2010’s CO2 • ?

  4. World’s Tallest Stacks 2nd GRES-2 Power Plant, Ekibastuz, Kazakhstan 1377 ft Inco Superstack at the Inco Copper Cliff smelter, Sudbury, Ontario 1277 ft

  5. Electrostatic Precipitators (ESPs)

  6. ESP Applicable boiler sizes:25 MW to 1300 MW. Source: babcock.com

  7. ESP Performance Normally applied in several stages (2 to 4) to maximize collection efficiency Source: EPA

  8. Baghouse limited by operating temperature Source: pcsesp.com

  9. Cyclone

  10. Fly Ash Collection Fly Ash Silo

  11. Wet Scrubber

  12. Basic Scrubber Flows

  13. Burner Designs Original Recent Past Current Sources: Babcock and Wilcox Unizar

  14. Principle of Low NOx Burners • Fuel and air mixed at an angle • Suppression of fuel and air in initial combustion stage • Fuel not burned initially mixes with air not used initially • Higher temp region cannot develop • Lower flame temp and local oxygen partial pressure

  15. Low NOx Burners www.einstrumentsgroup.com www.fluent.com/software

  16. Comparison of Flames Decreasing NOx HT-NR HT-NR2 HT-NR3 Stable, brilliant flame Higher NOx Lower Combustion Efficiency Wider, shorter flame Lower NOx Higher Combustion Efficiency Source: www.bhk.co.jp

  17. Nitrogen Oxides (NOx) • Contribute to acid rain • Can also form ozone and reduce visibility • Formed from 2 sources • fuel • combustion air • Initial control (late 70’s) was staged combustion • Fire in stages • Restrict oxygen where temp. is highest • Led to low NOx burners • Installed at 75% of large coal plants • Typical NOxreductions of 40 to 60% Source: www.netl.doe.gov/KeyIssues/future_fuel.html

  18. Selective Non-Catalytic Reduction (SNCR) • Post combustion process • Lower temperature required • Typically at top of boiler by-pass • Nitrogen-based reagent injected • Typically urea or ammonia • NOx converted to N2 and H2O • Typical NOx reductions of 35-50%

  19. Selective Catalytic Reduction (SCR) Source: procom.kaist.ac.kr

  20. SCR Reactor www.netl.doe.gov http://english.hhi.co.kr www.dom.com

  21. Reaction Mechanism in SCR Reactor Selective Reactions 6NO + 4NH3 → 5N2 + 6H2O 4NO + 4NH3 + O2 → 4N2 + 6H2O 6NO2 + 8NH3 → 7N2 + 12H2O 2NO2 + 4NH3 + O2 → 3N2 +6H2O NO + NO2 + 2NH3 → 2N2 + 3H2O Non-selective Reactions 2NH3 + 2O2 → N2O + 3H2O 4NH3 + 3O2 → 2N2 + 6H2O 4NH3 + 5O2→ 4NO + 6H2O

  22. US Coal Production Million tons Source: EIA

  23. SO2 • Combines with water vapor to form dilute acid • acid rain • Sulfur sources • coal • volcanoes • biological decomposition • Clean Air Act (1970) reduced SO2 emissions • Initial reductions by coal cleaning • First US commercial coal-utility scrubber built in 1967 • Union Electric, MO • Clean Air Act (1977) essentially mandated scrubbers • 52 scrubbers operating in 1982 • 190 scrubbers operating in 2008 • Mandatory after 2018 • Typical SO2 reductions >90% Source: www.netl.doe.gov/KeyIssues/future_fuel.html

  24. Title IV of the Clean Air Act amendments of 1990 • Cut SO2 emissions by 50% from 1980 level • Installing technology to reduce SO2 • Fuel switching • Allowance trading • Phase I: Jan 1, 1995 • Effected 110 plants (263 units) from 61 utilities, mainly in the East • SO2 could only be emitted within allowance range • EPA issued allowances to each unit • Based on 1985-1987 baseline • More earned by installing technology to reduce by 90% • Allowances could be traded or sold • Phase II: Jan 1, 2000 • Program continued with lower emission levels • 1.2 lbs/MMBtu/unit • Phase III: Jan 1, 2010 • Program continues with national emissions cap • 8.95 M tpy

  25. SO2 Allowances or Credits circa 2006 1 Credit = 1 Ton

  26. SO2 Credit Market Today • 2004 EPA determines that 28 states and DC contributed significantly to non-attainment in downwind states • 2005 EPA issues Clean Air Interstate Rule (CAIR) • regional caps • reduced aggregate cap • 2008 CAIR challenged on a number of grounds • ruling vacated • appeal remanded rules to EPA without vacating them • 2010 EPA issues Transport Rule (a.k.a. Cross-State Air Pollution Rule) • Sets state by state emissions budgets • Very limited interstate trading • Price of SO2 allowances goes to zero

  27. Cross-State Air Pollution Rule (CSAPR) • requires 28 states in the eastern half of the U. S. to reduce power plant emissions that cross state lines • cap and trade system is used to reduce the target pollutants—SO2 and NOx • Vacated by the United States Court of Appeals for the D.C. Circuit, August 21, 2012 • CSAPR exceeds the EPA’s statutory authority • CAIR remains in place to reduce SO2 and NOx

  28. States covered by CAIR

  29. Clean Air Interstate Rule • two phases for reductions in NOx and SO2 • Phase I 2009 through 2014 • 50% reduction for all units in the affected state • Phase II will begin in 2015 and continue indefinitely • 65% reduction

  30. EPA Train Wreck Chart

  31. Rainfall and Rainfall pH 1994 2000 2007

  32. Source: EPA

  33. Scrubbers and Hg

  34. Source: wattsupwiththat.com

  35. Estimated market for FGD for coal-fired power plants, 1996-2010. Source: IEA

  36. Kentucky Electricity Generation, 2010

  37. Kentucky Pollution Abatement Capital Expenditures, 2005

  38. Annual SO2 and NOXEmissions 2005 2009

  39. Annual SO2, NOXand CO2Emissions, 2009

  40. 2000-2011 http://iopscience.iop.org/1748-9326/8/1/014003/article

  41. Emission rates of SO2 from an active volcano range from <20 tonnes/day to >10 million tonnes/day Mount Pinatubo (1991) injected about 20 million metric tons of SO2 into the stratosphere There are about 1,500 active volcanoes in the world

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