Ashworth Combustor™

ClearStack’s multi-pollutant reduction Ashworth Combustor™ is a breakthrough, 3-stage combustion technique that reduces the major air pollutants associated with coal combustion (SO2, NOX, Hg and particulate) in the most environmentally friendly manner ever. Limestone is added with the coal to capture sulfur, mercury and other heavy metal air toxins produced in the slag and fly ash. Further, up to 20% biomass can be fired with coal to meet EPA Renewable Energy Standards.The Ashworth Combustor also removes a high percentage of the coal ash in the combustor vessel, reducing the rate of particulate entry into the boiler. Consequently, less particulate in the flue gas enters the downstream electrostatic precipitators and, thereby, the atmosphere.

Environmental advantages:

  • Reduces particulate matter (PM) emissions 90% to 95% for boilers with electrostatic precipitators (ESP)
  • Reduces Sulfur Dioxide (SO2) emissions by 90% to 95%+ depending on CaCO3 particle size
  • Reduces Nitrogen Oxides (NOX) emissions down to 0.070 to 0.095 lb/million Btu
  • Reduces Mercury (Hg) emissions by 90+% (captured mercury does not leach)
  • Reduces Sb, As, Ba, Be, Cd, Cr, Co, Cu, Hg, Pb, Mo, Ni, Se, Ag, Tl, V, Zn and Mn by 80+%
  • Reduces Ag, As, Ba, Cd, Hg, Pb, and Se all well below the EPA regulatory limits, as shown by slag and fly ash leachate tests (TCLP)
  • Reduces chlorine by 13% and fluorine by 26%
  • Reduces CO2 emissions with co-firing of up to 20% biomass with coal

Economic advantages:

  • Costs the least of any multi-pollutant retrofit control technology
  • Requires minimal space compared to other pollution control techniques
  • Yields lower heat rate than current IGCC units when combined with supercritical boilers
  • Does not require chemical plants on back-end of boiler

This technology is protected under U.S. Patents #5,458,659, #6,085,674, and #6,325,002.
Ashworth Combustor Technology Description