1. Why Is Flue Gas Conditioning Needed?
- Burning coal to produce electricity causes the emission of sulfur oxides such as sulfur dioxide and sulfur trioxide, or acid gas. This gas is carried into the atmosphere, along with fly ash generated from the combustion of the coal. When these acid gases combine with moisture in the atmosphere, they form dilute solutions of sulfuric acid or "acid rain" which fall back to earth, damaging the environment.
- High sulfur coal has traditionally been the standard fuel for coal-fired boilers and the fly ash produced from this fuel is readily collectable in electrostatic precipitators. Regulations restricting sulfur dioxide emissions are being implemented worldwide. In an attempt to comply with these new limitations, the power industry has begun the switch to lower sulfur coals. Low sulfur coal tends to generate more fly ash and flue gas per megawatt. Because of the higher resistivity of this ash, it is difficult to collect in existing precipitators.
- Two solutions are to install much larger and more expensive precipitators or fabric filters for collection of the fly ash. Another, more cost-effective alternative, is flue gas conditioning. Flue gas conditioning restores the collection efficiency of the precipitators to performance levels consistent with the firing of high sulfur coal.
- Wahlco offers a wide variety of methods to create sulfur trioxide for injection, each suited to varying utility applications. Additionally, we supply systems to inject ammonia, which either by itself or in combination with sulfur trioxide, provides unique solutions to particularly difficult fly ash collection problems.
