such that pressure reduction does not take place with its associated risk of steam blowing through up through the column of chips which can disturb the passage of chips and generate foul smelling gases that are expelled from the chips and are not bound in the withdrawn impregnation fluid rec the following table gives suitable positions for the addition of different impregnation fluids at different temperatures at atmospheric pressure or at a pressure of u00b1 0 5 bar at the top of the impregnation vessel the first second and third impregnation fluids bl 1 bl 2 and bl 3 are in the method according to the invention principally established from one common flow of black liquor that has been withdrawn from a subsequent cooking stage it is appropriate that the black liquor which already has a high temperature when withdrawn form the digester constitutes more than 50 and preferably more than 75 of the impregnation fluid energy can be managed in this way in an efficient manner the relevant subflows bl 1 bl 2 and bl 3 with different temperatures are obtained in that the common flow bl is divided into at least two flows one cooled flow and one non cooled flow the temperature of the first impregnation fluid bl 1 is adjusted by cooling the black liquor bl the third impregnation fluid bl 3.