The process of burning coal in a coal-burning power station involves the following steps:

1. Washing coal: The coal is crushed and washed to remove sulfur from its surface. When the coal is placed in a water-filled tank, the coal floats to the surface while the sulfur impurities sink to the bottom.
2. Furnace 1: A mixture of coal and limestone floats on a stream of hot air in the furnace. Calcium carbonate in the limestone reacts with sulfur dioxide to form calcium sulfate. The amount of air is limited and the temperature is held low to keep nitrogen from reacting with oxygen.
3. Cyclone separator: The cyclone separates the unburned fuel from the hot gases.
4. Furnace 2: Unburned coal from the first furnace is transferred into furnace 2 for further burning. More limestone is added to react with any sulfur dioxide produced.
5. Boiler: Water from the condenser flows through pipes in the boiler. Hot gases from furnace 2 are fed into the boiler to heat the water. The steam created is used to spin a steam turbine. The hot gases are fed back to furnace 2 so unburned fuel can react.
6. Particle filter: Hot gases from the furnaces are fed through filters made of tightly woven fabric. The filters trap tiny particles of coal and ash and prevent them from entering the gas turbine.
7. Heat exchanger: Waste gases are cooled in the heat exchanger by a coil containing cold water. The cooled and cleaned gases, containing dramatically reduced amounts of sulfur dioxide and nitrogen oxides, are emitted from the chimney.