Process and apparatus for the treatment of fibrous materials in the production of cellulose or semi-cellulose

Claim 1

IN A PROCESS FOR THE TREATMENT OF FIBROUS MATERIALS IN THE PRODUCTION OF CELLOULOSE OR SEMI-CELLULOSE IN WHICH THE FIBROUS MATERIALS ARE IMPREGNATED WITH DIGESTING LIQUID AND DIGESTED AT SUPERATMOSPHERIC PRESSURE AND ELEVATED TEMPERATURE, THE METHOD OF IMPREGNATING SAID MATERIALS COMPRISING THE STEPS: CONTINUOUSLY CIRCULATING AN EXCESS QUANTITY OF DIGESTING LIQUID IN A CLOSED FLOW PATH WHICH INCLUDES FIRST, SECOND AND THIRD PORTIONS, SUBJECTING SAID LIQUID TO ATMOSPHERIC PRESSURE IN SAID FIRST PORTION OF SAID FLOW PATH, TO VACUUM IN SAID SECOND PORTION OF SAID FLOW PATH AND TO AT LEAST ATMOSPHERIC PRESSURE IN SAID THIRD PORTION OF SAID FLOW PATH; CONTINUOUSLY ADMIXING THE MATERIAL TO BE IMPREGNATED WITH THE CIRCULATING DIGESTING LIQUID IN SAID FIRST PORTION; LEADING THE SO-OBTAINED MIXTURE TO SAID SECOND PORTION; SEPARTING PART OF THE CIRCULATING MATERIAL AND LIQUID FROM ONE ANOTHER DURING CIRCULATION THROUGH THE SECOND PORTION; RECOMBINING THE MATERIAL JUST SEPARATED AND THE CIRCULATING LIQUID AS THE MATERIAL LEAVES THE SECOND PORTION; SEPARATING THE MATERIAL FROM THE CIRCULATING LIQUID IN SAID THIRD PORTION OF THE PATH AND REPLACING WITH NEW LIQUID THE LIQUID WHICH IS ABSORBED AND ABSORBED BY THE MATERIAL; AND RECIRCULATING THE LIQUID THROUGH THE FLOW PATH.