METHOD AND SYSTEM FOR RECYCLING OF REJECTS IN A PROCESS FOR COOKING CHEMICAL PULP

摘要

The present invention relates to a method and system for cooking of chemical pulp, and relates in particular to a process for dealing with rejects in conjunction with the cooking of chemical pulp. According to the invention is a chopper pump 12 used for recirculating a flow a rejects in a reject vessel 11, said chopper pump having at least one cutting edge on the impeller and a cooperating anvil in the pump housing. A part flow Q3 is splitted from this recirculation flow and fed to the digester via a high pressure pump 13, said part flow preferably being less than 50% of the total flow Q1 pumped by said chopper pump. The rejects in the reject vessel is also preferably slurried with treatment liquor that is to be added to the cooking process. The invention will obtain a repeated defibration effect on the rejects and prepare them for a complete delignification in next passage of the digester and thus reduce the reject volumes over time.