Patent ID: 7279070

Claim:
A method for the continuous cooking of wood raw material in the form of sawdust for the production of cellulose pulp, comprising; continuously feeding sawdust to a top of a steaming vessel, steaming/heating the sawdust with steam in a steaming vessel, adding a washing filtrate to the steaming vessel, the washing filtrate forming a cooking fluid, the cooking fluid heating the sawdust to a temperature of 80-100° C., impregnating the sawdust with a cooking fluid at a bottom of the steaming vessel, discharging a mixture of sawdust and cooking fluid from the bottom of the steaming vessel, more than 95% of the cooking fluid added to the sawdust accompanying the sawdust in the mixture of the cooking fluid and the sawdust; pressurizing the mixture by a pump for transporting the mixture onwardly to a top of a cooking vessel without further heating of the sawdust, transferring the mixture to the cooking vessel without draining any cooking fluid from the sawdust; establishing a level of the sawdust in the cooking vessel that is above a level of the cooking fluid in the cooking vessel, in a steam phase, adding steam to the top of the cooking vessel to heat the sawdust with steam while the sawdust falls through the steam phase at the top of the cooking vessel and heating the sawdust that lies above the level of the cooking fluid to a cooking temperature within a temperature interval of 130-160° C., cooking the sawdust in the cooking fluid for a cooking time within a time interval of 60-300 minutes, discharging the sawdust and the cooking fluid to a pressurized diffusion washer, expelling the cooking fluid from the sawdust by using a washing fluid while a pressure is maintained, the expelled cooking fluid forming a washing filtrate, adding white liquor to the steaming vessel, and forming the sawdust into a slurry in the steaming vessel with the cooking fluid so that a consistency of the slurry is 20% or less.