The Thermal Recovery Facility (TRF) in Bolton generates enough power to operate the facility, plus approximately seven MW of electricity, which is then transferred to the National Grid.
Thermal Recovery is a process by which the energy produced from burning waste is used to create electricity. The waste is burned at high temperatures turning the carbon and hydrogen present in the original waste into carbon dioxide and water respectively.
When waste arrives at the facility it is tipped into a reception hall where a mechanical shovel is used to move the waste into a 10m deep pit. A grab is used to mix the waste, helping to prevent too much of one type of material being burned at once.
The waste is transferred to the furnace where it is incinerated. The furnace can reach temperatures of over 850°C and reduces the waste to ash. Five grates move the waste along to ensure it is completely burned. The ash falls out of the bottom of the furnace and is cooled with water then passed under a magnet to remove any ferrous (iron-based) metals, which is separated for recycled. The remaining ash is either used in construction materials or sent to landfill.
The heat generated from the furnace is used to boil water, which creates steam. The steam is then used to power a turbine which spins at 6,900 revolutions per minute, that turns a gearbox and drives the generator to produce electricity.
Gas Cleaning System
Ammonium, lime and activated charcoal are added to neutralise acid gases and other potential air pollutants. The gases then pass through a bag filtration system which removes the additives and any other particles. This is known as “fly ash” and it is sent for safe disposal.