Technologies


Dual Conditioning

In some cases of high ash resistivity, sulfur trioxide flue gas conditioning alone is not effective. Some of these are:

  • The fly ash does not absorb the sulfur trioxide. This is generally true of fly ash that has a combined silica-alumina content of more than 90% and a low concen­tration of alkali metals. These ashes are fre­quently referred to as acidic ashes.
  • Flue gas temperatures are too high for the sulfur tri­oxide to attach to the ash. This can be as low as 320°F (160°C) and depends on ash composition and gas moisture.
  • High precipitator gas velocities. The performance improvement from lowering ash resistivity is offset by increased re-entrainment due to lower ‘holding forces.’
  • High unburned carbon carryover in the ash. The carbon particles do not hold a charge. In addition they are extremely fine and will increase the stack opacity without a proportional increase in mass loading. When the carbon carryover exceeds about 10%, re-entrainment becomes a severe problem
The simultaneous and independent injection of both ammonia and sulfur trioxide referred to as dual gas con­ditioning can be an effective solution to these problems.

In addition to sulfur trioxide FGC systems, we also supply both anhydrous and aqueous ammonia systems for dual FGC (SO3 and NH3), and for the removal of nitrogen oxide (NOx) air pollutants using the selective catalytic reduction (SCR) or selective non-catalytic reduction (SNCR) processes.

We have developed and patented a process to generate ammonia, as needed using urea feedstock. This process eliminates the requirement for on-site storage of anhydrous or aqueous ammonia.

Click here for a list of Chemithon's Dual Conditioning Plant installations


SO3 Conditioning NH3 Conditioning Dual Conditioning