Single vessel reactor system for hydrolysis and digestion of wood chips with chemical enhanced wash method

摘要

A reaction vessel (10) comprises: a material input receiving cellulosic material and a material discharge for the cellulosic material, wherein the cellulosic material flows through the reaction vessel (10) from the material input to the material discharge; a hydrolysate and liquid extraction screen (26); a hydrolysis zone (A) between the material input and the hydrolysate and liquid extraction screen (26), wherein the hydrolysis zone (A) is maintained at or above a hydrolysis temperature at which a hydrolysis reaction occurs in the cellulosic material; a wash zone (B) between the hydrolysate and liquid extraction screen (26) and a wash liquid extraction screen (33), wherein the hydrolysis is substantially suppressed in the wash zone (B); a wash liquid inlet port (61) for introducing a wash liquid into the wash zone (B), wherein at least a portion of the wash liquid entering the wash liquid inlet port (61) flows through the wash zone (B) and is extracted by the hydrolysate and liquid extraction screen (26), and wherein the wash liquid is introduced to the wash zone (B) at a temperature below the hydrolysis temperature; a cooking zone (D) between the wash zone (B) and the material discharge, wherein said cooking zone (D) includes a cooking liquor injection port; and a cooking liquor extraction screen (54) at or below the cooking zone (D) and above the material discharge. The wash liquid is a mixture of water and at least one of sodium hydroxide and essentially sulfur free white liquor.