Extrusion method and apparatus for acid treatment of cellulosic materials

Abstract

An improved, low cost, energy efficient extrusion device and method for processing of cellulose, hemicellulose, and like fiber-bearing materials is described which includes a pretreatment extrusion zone and a reaction extrusion zone separated by a pressure sensitive variable die. The method hereof includes the steps of extruding cellulosic material through the pretreatment zone at an elevated pressure and temperature, passing the material into the reaction zone where it is mixed with an acid and is processed at a lower pressure and temperature than in the pretreatment zone, and extruding the material through a final extrusion die. The surging and blowing usually experienced with extrusion of fibrous material is drastically reduced by the unique construction of the extruder die members. The cellulosic material may be hydrolyzed to simple sugars in accordance with the method and apparatus hereof with a minimum of acid degradation of the extrusion equipment. The sugars produced from the cellulosic material may in turn be converted into ethanol or other usable fuels by the process of fermentation.