Gasification can be defined broadly as the thermochemical conversion of a solid or liquid fuel into a combustible gas product.
The process takes place at high temperatures (greater than 800°C), either in the absence of oxygen, or more commonly with a sub-stoichiometric supply of oxygen or air. Steam is commonly added. The product produced is a fuel gas consisting typically of carbon monoxide and hydrogen together with some methane, carbon dioxide, nitrogen (if air-blown) and water vapour. This fuel gas can be used to power gas engines or gas turbines for the generation of electricity. Alternatively the gas can be utilised as a feedstock (syngas) for the production of various chemicals, for instance methanol.
Gasification essentially converts a solid carbon feed into a more practical and versatile gas.
Gasification research at EBRI
Current gasification research activity by EBRI researchers involves the coupling of an intermediate pyrolysis technology developed by EBRI - the Pyroformer™ - with a fluidised bed gasifier. The aim is to deliver a purely gaseous fuel from the pyrolysis of a wide range of traditionally difficult, low-value feedstocks.
As well as the attraction of having a simple and easy to handle product, this arrangement also avoids the need for a condenser, filtration unit and aerosol precipitator which are required for a stand-alone pyrolysis process. It also provides for the separation before gasification of a fraction of biochar which is valuable in its own right, but which also contains all the ash components of the feed. Such components could cause serious problems within the gasifier itself.
EBRI also carries out more fundamental studies into downdraft and fluidised bed gasification using a combination of laboratory-scale units and computational modelling. One particular area of interest is dual fluidised bed gasification where the gas is produced in the absence of oxygen in one bed, and the resulting char is separated and combusted in a second bed in order to return the necessary heat to the first bed.