Apparatus for chemical conversion of materials

In an apparatus for the dilute sulfuric acid hydrolysis of waste cellulose and being of the type comprising:

• extruding means including a housing having inlet ports receptive of cellulose to be converted, dilute sulfuric acid and steam or superheated water, an outlet port and a reaction zone therebetween;
• twin screws mounted in the housing for continuously, conveying the cellulose through the reaction zone and to the outlet port;
• means defining supply sources of waste cellulose, dilute sulfuric acid and steam or superheated water, said supply means being connected to the respective inlet port;
• means for continuously feeding the cellulose to the waste cellulose inlet port;
• means for continuously injecting dilute sulfuric acid into the reaction zone;
• means for effecting an elevated temperature and pressure with the reaction zone during discharge comprising means for continuously injecting steam or superheated hot water at elevated pressure into the reaction zone and means for maintaining the elevated temperature and pressure including means forming a dynamic seal of the cellulose at the upstream end of the reaction zone and valve means downstream of the outlet port, the improvement wherein the means forming the dynamic seal comprises means forming a radially recessed and unthreaded discontinuity in the twin screws.