Patent ID: 7077930

Claim:
A method of controlling quality of pulp comprising; producing the pulp by mechanical refining, screening the pulp thereby obtained at a screening phase to provide at least two fractions, the accept that has passed the screening phase being carried forward for later use and reject that has not passed the screening phase being led out of the screening phase, determining flow amount and consistency of the pulp to be supplied to the screening phase, and correspondingly, of the reject removed from the screening phase, calculating, based on the flow amounts and consistency values, a passage ratio of the reject and the supplied pulp using the formula P = log ⁡ ( RR m ) log ⁡ ( RR v ) wherein P is the passage ratio, RR m is the mass-to-reject ratio of the screening phase, and RR v is the volume-to-reject ratio of the screening phase, and adjusting the screening phase according to said passage ratio.