Plasma
Advanced Plasma reactors convert waste into synthetic gases with the aim of removing unwanted materials and recycling energy and as a result is often defined in terms of a type of gasification. The main component is the gas plasmas which are formed by freeing electrons from gas molecules and atoms using external energy sources. Insignificant emissions of flue gases and very high efficiency in these reactors have created a high incentive for using them and an established commercial technology. However, it can be a very complex, expensive and operator-intensive process[1]. Different types of wastes including municipal, clinical, hazardous, chemical dissolvent, heavy metals, and plastics can be thermally treated using this method[2].
Plasma Incineration Reactor
Parts of the Plasma reactor explained:
- The waste input at the top where feedstock enters the chamber.
- The lower part holds the feedstock, and also includes the Plasma torch. Plasma torches are where the Plasma current is created due to the interactions between gases and the electric arc among the electrodes.
- The higher part of the chamber has the capacity to provide enough time for keeping the volatile gases for complete disintegration.
- Synthetic gas outlet which transports the resulting flue gases to create electricity.
- The waste collector and discharger collect the by-products such as bottom ash and sludge which exit the chamber[2]
.
Plasma Incineration Mechanism
The Plasma technology creates a very high temperature, between 1000-15,000°C[3], due to a direct current between the anode and cathode of the Plasma torch. This extremely high temperature in chamber completely decomposes the waste and organic and poisonous compounds in milliseconds. Plasma processes have high destruction efficiencies of >99.99%[1] and so the production of secondary combustion products and polluted gases is avoided. Instead, synthetic gases are produced that are used to generate electricity or can be used in various industries as a substitute for diesel fuels. Minerals are converted into melting residuum/ash for discharge or it can be used in recycling and petrochemical industries[2].
Application in UK
The only known application of the technology in the UK was the Alter NRG technology at Air Products in Teeside, where two 50MW facilities (TV1 and TV2) were progressed before being suspended at an advanced construction stage in late 2015 due to technological issues[4].