Method of using reactor vessel having single convergence sidewall plates

A method to process biomass in a reactor vessel comprising:

• continuously feeding comminuted biomass to an upper inlet of the reactor vessel;
• continuously adding water or other liquor to the biomass such that a liquid level in the reactor vessel is substantially below an upper level of the biomass in the reactor vessel;
• treating the biomass in the reactor vessel;
• continuously discharging the treated biomass from a bottom outlet of the reactor vessel;
• as the biomass flows gradually and continuously downward in the reactor vessel from the upper level of the biomass to the bottom outlet, moving the biomass between a plurality of pairs of support plates, wherein (i) the pairs of support plates are arranged at different elevations in the vessel, (ii) the plates of each pair are mounted to a sidewall of the vessel at a slope with respect to the sidewall that converges the plate inwardly towards an opposite plate along a downward direction, and (iii) the convergence of each pair of plates is along a single direction of convergence;
• gradually increasing compaction of the biomass as the biomass flows down between each pair of support plates;
• rapidly releasing some of the compressive forces on the biomass as the biomass flows past lower edges on each pair of support plates.