the fibrous ceramic materials and for structural strength the thicknesses of the walls are chosen to minimize energy loss the particular materials used to construct the walls and the thicknesses of the walls are determined by the particular operating temperature selected for the reactor for example if the maximum operating temperature in the chamber is to be 1400 u00b0 c the materials forming the chamber should be suitable for temperatures up to 1500 u00b0 c or more with these temperatures the walls should be at least six inches thick so that the outer shell temperature of the reactor 10 will be sufficiently low so as not to constitute a health or safety hazard and to reduce energy losses from the reactor fibrous ceramic materials that may be used for this purpose include those marketed by the carborundum company of niagara falls n y under the trade designation 34 fiberfax 34 the interior walls of the gasifier 10 are lined with a material chosen to resist the abrasive forces of the solid fuels that may be processed in the gasifier materials that may be suitable for this purpose include the porous ceramics marketed by hitech ceramics of alfred new york under the trade designation 34 udicell 34 the gasifier 10 may be used to process a variety of different types of solid fuels these materials can include anthracite coal bituminous coal peat solid wastes of all kinds and biomass materials as well as mixtures proportioned as discussed below the solid waste materials may be in a variety of assorted shapes and sizes the materials need not be pre treated they can be processed as they are received from their sources except the materials may have to be roughly shredded mechanically or reduced to a size and shape.