Converting waste into valuable resources with the Gasplasma process
This paper reports on a novel process development to convert waste into renewable energy using gasification. Advanced Plasma Power (APP) has developed an advanced thermal conversion technology, (Gasplasma ), capable of treating a wide range of organic and inorganic wastes. In the two-stage thermal process, the fluidised bed gasifier (FBG) converts the waste to a crude syngas containing significant levels of char, ash, tars and other liquid organic contaminants. This gas stream, together with the char and ash product from the gasifier, is then treated in a high temperature plasma converter unit to produce a reformed and consistent quality synthetic gas (syngas) which (after tertiary cleaning of the acid gases and particulates) is suitable for high efficiency generation of power in a gas engine or gas turbine. The inorganic ash fraction is vitrified in the plasma converter unit to produce a dense, environmentally stable vitrified product (Plasmarok ), which has a wide variety of end uses and leads to a very low level of waste requiring disposal. An important aspect of the design concept was to employ commercially tried and proven techniques. The breakthrough innovation stems from how these technologies have been effectively integrated to enable the highly efficient production of a clean syngas and secondary aggregate.The electrical conversion efficiency that can be achieved using a gas engine is c.40% compared to 25% for a steam turbine system (at an equivalent thermal input), in the past, it has been the problem of tar and char contamination of the syngas, associated with conventional gasifiers, that has prevented the widespread adoption of waste gasification to power gas engines and turbines.The operation of the Swindon (UK) facility, since 2007 has continually demonstrated the successful integration of the main process elements, producing a syngas that can be utilised directly in a gas engine/turbine.
This very high efficiency and flexible advanced thermal process uses proven technology in a unique combination and can be used to provide power from RDF and other wastes. The plant is compliant with all EU emissions limits and has a high level of availability. Apart from producing power through gas engines or turbines the clean syngas has other potential uses within the liquid biofuel sector as well as the hydrogen economy. The standard size of the plant has been set at 150,000 tonnes of MSW or 90,000 tonnes of RDF per annum but it is scalable for larger cities.