ClearStack’s Cleargas™ is a trimming dry scrubber that remove SO2 and NOX and improves electrostatic precipitator performance at low capital and operating cost.

The ClearGas™ scrubber uses potassium hydroxide (KOH) to reduce sulfur oxides and nitrogen oxides from flue gases by 70-90%. It will also remove sulfur trioxide (SO3), reducing flue gas opacity.

Aqueous potassium hydroxide (KOH) is spray dried into the flue gas using in-duct injection or a dry scrubber. The KOH reacts with SO2 to form K2SO4, and reacts with NO and NO2 to form KNO3, both salts of which are captured and removed with the fly ash from a downstream electrostatic precipitator (ESP) or baghouse. The presence of potassium salts in an ESP decreases resistivity and increases the “spark over” voltage, improving particulate removal performance even though SO3, a fly ash conditioning agent, is removed in the process.
This produces a byproduct of salable potassium nitrate, potassium sulfate-fly ash fertilizer.

Economics show that this dry scrubber technology is a low-cost technique for bringing small, coal-fired stokers into environmental compliance. It is less costly than a stoker replacement with a natural gas-fired boiler system or a conversion to coal-fired fluidized bed combustion systems. It also can be used as an SO2/NOX trim technology for large, coal-fired electric utility boilers.

This technology is protected under by U.S. Patent #6,363,869.

ClearGas Dry Scrubber Technology Description