Coal steam turbine

 

Plant Scherer, Coal Steam Turbine
Coal electric generation (source: water.usgs.gov)

A coal steam turbine burns coal to create steam. Here's how this process works. Since coal typically arrives at a power plant via barge or train, most coal power plants need an onsite fuel storage system. After moving the solid fuel from where it's stored, the coal must be prepared for burning by crushing it to create particles that are sized appropriately for the two technologies that are most commonly used. The pulverized-coal furnace burns finely powdered coal suspended in air while the fluidized-bed furnace burns larger particles of crushed coal, ash, and a solid material such as limestone. The various particles are mixed in a bed that is then levitated by combustion air entering the bottom of the furnace.

Furnace sizes for coal units are large since the ash created during the combustion process requires large heat transfer surfaces. Emissions control equipment is an important part of a coal power plant. This typically includes electrostatic precipitators and bag filterhouses to control particulates and stack scrubbers to remove sulfur dioxide, or SO2. Emissions of NOx are generally controlled through design of the burners in the combustion process.