APPARATUS AND PROCESS FOR SCREENING A FIBRE SUSPENSION AND PROCESS FOR PRODUCING PAPER UTILIZING THE SAME

摘要

The present invention relates to an apparatus and a process for screening a fibre suspension such as papermaking stock in a pressurized screen especially in connection with pumping said liquid. The invention also relates to the use of the apparatus in a process for the production of paper or board. The apparatus comprises a generally tubular housing (12) and a perforated screen-drum (22) inside said housing. The housing (12) and screen-drum (22) define between themselves a generally annular screening zone (30). The screen-drum (22) surrounds a tubular accept channel (32). The apparatus further comprises inlet means (14) for inject, outlet means (19) for accept, and outlet means (17) for reject. The screen-drum (22) is rotatable within said housing (12) and means are provided for introducing diluting fluid into said annular screening zone (30) at a plurality of locations along its axial extent. The accept outlet end of said housing (12) preferably widens into a pumping chamber (18) having a pump wheel (26) for pumping the screened suspension.