Method for the feed of cellulose chips during the continuous cooking of cellulose

A method for feeding a slurry of cellulose chips and fluid from a low-pressure system to a high-pressure system during a continuous cooking of chemical cellulose pulp, comprising:

• feeding a slurry of cellulose chips and fluid from a low-pressure system to a high-pressure system in an arrangement of a sluice feeder (53′) between the low-pressure and high-pressure systems for transporting the fluid and cellulose chips through the sluice feeder,
• providing the sluice feeder (53′) with a first inlet (53a′), a second inlet (53c′), a first outlet (53b′) and a second outlet (53d′) and a rotor with a first through pocket (1) and a second through pocket (2), the first and second pockets (1,2) being movable into a first position and a second position, the first pocket being in connection with the low-pressure system when in the first position while the second pocket being in connection with the high-pressure system when in the second position, the pockets being alternately placed into connection with the high-pressure system and the low-pressure system where the first pocket (1), when located in the first position, being in contact with a chip chute (52′) or with an impregnation vessel (3) essentially at atmospheric pressure in the low-pressure system via the first inlet (53a′),
• filling the first pocket (1) with a chips mixture while at the same time expelling a first expulsion fluid that is present in the first pocket (1) via the first outlet (53b′) and the second pocket (2), which is in the second position, being in connection with a transfer line (6b′) in the high-pressure system via the second outlet (53d′),
• expelling the chips mixture from the second pocket (2) for transporting the chip mixture onwardly to a treatment vessel (60′) in the high-pressure system with an aid of a second expulsion fluid that is fed into the second pocket (2) via the second inlet (53c′),
• providing a recirculation line (54′) having a high-pressure pump (57′), the recirculation line extending from the first outlet (53b′) of the sluice feeder to the second inlet (53c′) of the sluice feeder for transporting expulsion fluid that has been expelled from the pockets of the sluice feeder when the pockets are being located in the first position, and
• using the second expulsion fluid to expel the chips mixture from the pockets of the sluice feeder when the pockets are located in the second position, the second expulsion fluid being essentially exclusively constituted by the first expulsion fluid that has been expelled from the pockets of the sluice feeder when the pockets are located in the first position.