NOVELTY - Transferring plant-based biomass slurry into reactor vessel, by combining transport fluid with the biomass made of discrete pieces, pressurizing obtained pre-reaction slurry at 300 per square inch (psi) or more, removing at least portion of the transport fluid from the pressurized pre-reaction slurry to obtain pressurized concentrated slurry, combining the reaction fluid with the pressurized concentrated slurry to obtain pressurized reaction slurry, and transferring the pressurized reaction slurry from the pre-reactor vessel into the reactor vessel.    USE - The Method is useful for transferring plant-based biomass slurry into reactor vessel to produce liquefied fuel product.    ADVANTAGE - The method enables production of bio-oil product from practical sized pieces of cellulosic or lignocellulosic biomass. The method is energy efficient, reliable, and continuous for feeding practical-sized biomass into a high pressure, high temperature reactor. The method enables varying the ratio of the biomass to liquid that enters the reactor. The method enables feeding the pressurized slurry of biomass into high pressure, high temperature reactor vessel without need to grind the biomass.    DETAILED DESCRIPTION - Method for transferring slurry of plant-based biomass into reactor vessel, involves (a) combining transport fluid with the plant-based biomass made of discrete pieces to obtain pre-reaction slurry, (b) pressurizing the pre-reaction slurry at 300 per square inch (psi) or more, (c) removing at least portion of the transport fluid from the pressurized pre-reaction slurry in pre-reactor vessel to obtain pressurized concentrated slurry with second weight ratio of fluid to biomass, (d) combining the reaction fluid from the reactor vessel with the pressurized concentrated slurry to obtain pressurized reaction slurry, and (e) transferring the pressurized reaction slurry from the pre-reactor vessel into the reactor vessel, where at least 20% of the discrete pieces have greatest dimension of at least 1/8 inch, pre-reaction slurry has first weight ratio of fluid to biomass, the first weight ratio of fluid to biomass is greater than the second weight ratio of fluid to biomass, and the pressurized reaction slurry is received at the reactor vessel at 300 psi or more.