Top separator with intraseal for digester vessel in a pulp or fiber processing system

A method for servicing packing material in a top separator assembly mounted on top of a digester, said method comprising:

• a. lifting a shaft extending from the top separator assembly and into the digester;
• b. while lifting the shaft, creating a fluid-tight seal between a sealing ring mounted on the shaft and a pack box housing the packing material, wherein said pack box includes a first annular surface around said shaft and said sealing ring has a second annular surface which abuts said first annular surface when said shaft is in an up-lifted position, wherein said first or second annular surface includes an annular ridge in sealing engagement with said second or first annular surface when said shaft is in said up-lifted position;
• c. refurbishing the packing material while maintaining a slurry in the digester under pressure using the seal formed by the sealing ring;
• d. lowering the shaft such that the packing material forms a seal between the pack box and shaft, wherein the lowering of the shaft forms a clearance between the sealing ring and the pack box, and
• e. rotating the shaft during operation of the digester, wherein the shaft is sealed by the pack box and the sealing ring is separated from the pack box.