Economics of chemical conditioning for improved precipitator performance

The presently preferred method to collect fly ash in coal-burning power plants is through the use of electrostatic precipitators. Precipitators are usually designed to provide high efficiency of collection of fly ash for the particular coals in use and specified at the time of order. Air quality maintenance and improvement regulations are now forcing many power companies to switch from over 2 percent sulfur content coal to low (less than 2 percent) sulfur coal as a means of meeting environmental restrictions on sulfur dioxide emissions. In many cases, this has resulted in deterioration of the precipitator efficiency with the result that particulate emissions exceed the code limits. This discussion focuses, in qualitative and quantitative terms, on means of chemically conditioning low-sulfur coal fly ash to improve its characteristics for better collection in electrostatic precipitators.