The Energy From Waste Facility
The non-recyclable waste arrives at the plant and is tipped into a large bunker. Unsuitable, large or non-combustible items are then removed by a crane.
The waste is fed into the combustion chamber, where air is added to aid the combustion process. The chamber has a number of grates which push and turn the waste until only ash remains. This ash is known as bottom ash and comprises inert ash and metals. It is collected from the facility and reprocessed off-site where the metals are removed and the ash used within the building industry.
The facility recovers energy from the waste in the form of heat from the combustion processes. A conventional boiler and economiser are used to turn the hot gases into steam. The steam produced is then fed into a steam turbine which generates electricity and hot water to deliver to the district heating network.
The flue gases from the combustion process have to be filtered and ‘cleaned’ of particulates and potentially hazardous elements before being released to the atmosphere via the stack. Lime and activated carbon are added to remove acid gases, nitrous and sulphur dioxides, dioxins and heavy metals. The solids produced, commonly known as fly ash, are collected prior to release of the clean gas to the atmosphere. The fly ash is disposed of safely by enclosed tanker to a designated landfill. It is considered hazardous due to the high alkalinity (caustic nature) of the material caused by the addition of lime.
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For a more detailed explanation of the process click here.