Biomass conversion systems having a fluid circulation loop containing backflushable filters for control of cellulosic fines and methods for use thereof

A method comprising:

• providing a biomass conversion system that comprises a fluid circulation loop comprising:
• a hydrothermal digestion unit;
• a solids separation unit that is in fluid communication with an outlet of the hydrothermal digestion unit;
• wherein the solids separation unit comprises a plurality of filters;
• and
• a catalytic reduction reactor unit that is in fluid communication with an outlet of the solids separation unit and an inlet of the hydrothermal digestion unit;
• providing a cellulosic biomass in the hydrothermal digestion unit;
• at least partially digesting the cellulosic biomass in the hydrothermal digestion unit to form a hydrolysate comprising soluble carbohydrates and cellulosic fines within a liquor phase;
• flowing the liquor phase through at least one of the filters to sequester the cellulosic fines;
• at least partially converting the soluble carbohydrates into a reaction product in the catalytic reduction reactor unit;
• and
• backflushing at least a portion of the cellulosic fines to the hydrothermal digestion unit using at least a portion of the reaction product.

A biomass conversion system comprising:

• a fluid circulation loop comprising:
• a hydrothermal digestion unit;
• a solids separation unit that is in fluid communication with an outlet of the hydrothermal digestion unit;
• wherein the solids separation unit comprises a plurality of filters;
• wherein the filters are in fluid communication with the fluid circulation loop in both a forward and a reverse flow direction;
• and
• a catalytic reduction reactor unit that is in fluid communication with an outlet of the solids separation unit and an inlet of the hydrothermal digestion unit;
• wherein at least one of the plurality of filters is in fluid communication with an inlet of the catalytic reduction reactor unit.