The energy-from-waste process

The energy-from-waste process

Waste collection vehicles discharge their waste into the bunker where the waste is mixed to ensure an even burn in the furnace.

Waste is loaded by crane into the feed hopper. The waste then goes down the feed chute into the furnace.

Inside the furnace, a series of grate bars move waste through the furnace where it is dried and burned at temperatures of 1000°C +.

The combustion system incorporates a seven staged air supply to optimize the process, and to ensure complete combustion.

The bottom ash from the grate drops into a slag extractor where it is cooled with water. The cooled ash is discharged onto a vibrating conveyer and is collected in the ash pit following ferrous metal recovery by the over band magnet.

Ammonia solution is injected into the flue gas when the flue gas temperature is between 950 and 1050°C. The ammonia reacts with nitrogen oxide produced in the combustion process, forming nitrogen and water.

Hot flue gases produced by the furnace travel through the boiler transferring heat to the water running through the boiler pipes generating steam.

An illustrative diagram of the EfW process

Power generation is achieved by passing the steam through a turbine. The turbine generates electricity for plant usage and export to the Manx grid.

Exhaust steam exiting the turbine enters the Air Cooled Condenser and is condensed back to water, which is feed back into the process.

A flue gas cleaning system cleans gases from the burnt waste. Lime slurry is added into the gas stream in the Spray Absorber to neutralize acidic gases. Activated carbon is introduced into the gas steam prior to the Bag Filters to remove dioxins and heavy metals.

The gasses pass through the fine fabric bag filters that capture any particles before the now cleaned gas is released through the stack.

The flue gas cleaning residues comprising of dusts from the fabric filters and dusts from the bottom of the Spray Absorber are stored in the Air Pollution Control Residue (APCR) silo before being sent for special treatment and disposal.

The flue gases flow through the stack where the continuous monitoring takes place. This monitoring then feeds back to the control processes.

Main links

You are here

Personal tools