Procedure For Controlling The Pulp Quality From Refiners

Abstract

The use of measurement information from traditional process variables along with measurement signals from the refining zones in refiners for the refining and grinding of pulp is disclosed for estimating the quality of pulp output from the refiner lines. Control of the refining process is thus improved by means of a method used with a series of refiners utilizing estimated pulp quality information from each refiner in order to be able to rapidly control the refining disturbances in the process.

1 - 8 . (canceled) 
     
     
         9 . A device for predicting pulp quality after refining, comprising at least a first refiner provided with a first spatially distributed set of temperature sensors and/or pressure sensors, a second refiner provided with a second spatially distributed set of temperature sensors and/or pressure sensors, where the at least two refiners are arranged in series, a pulp quality measuring device that infrequently and with a time delay provides an estimate of an absolute pulp quality of the pulp after refining in the at least two refiners, and a signal processing unit for frequently calculating a dynamic pulp quality estimate with a shorter time delay from the at least two spatially distributed sets of temperature sensors and/or pressure sensors, said signal processing unit further calculating a frequent pulp quality estimate with a shorter time delay from a function of both the absolute and the dynamic pulp quality estimates. 
     
     
         10 . A device according to  claim 9 , wherein the spatial distribution for the temperature sensors and/or pressure sensors in the at least two refiners comprise a radial distribution in the refining zones of the refiners. 
     
     
         11 . A device according  claim 9  wherein said the signal processing unit, when calculating the dynamic pulp quality estimate, further uses measured values from at least one of said at least two refiners regarding at least one measured value selected from the group consisting of plate gap, pulp dry content at the outlet, chip flow rate and inlet pressure. 
     
     
         12 . A device according to  claim 9 , wherein said pulp quality measuring device measures the pulp quality in a latency chest. 
     
     
         13 . A method for controlling pulp quality output from at least two refiners arranged in series comprising controlling the process variables of at least one of the refiners with a control device which controls the process variables based on input data in the form of at least a predicted pulp quality estimate, providing the at least two refiners with a spatially distributed set of temperature sensors and/or pressure sensors, estimating the absolute pulp quality of the pulp subsequent to refining in the at least two refiners with a pulp quality measuring device that infrequently and with a time delay provides said absolute pulp quality estimate, frequently calculating a dynamic pulp quality estimate with a shorter time delay from the at least two spatially distributed sets of temperature sensors and/or pressure sensors, and calculating a frequent pulp quality estimate with a shorter time delay, which constitutes input data to the regulation device, where the frequent pulp quality estimate is calculated from a function of both the absolute and the dynamic pulp quality estimate. 
     
     
         14 . A method according to  claim 13 , wherein said spatial distribution for the temperature sensors and/or pressure sensors in the at least two refiners comprises radial distributions in the refining zones of the refiners. 
     
     
         15 . A method according to  claim 13 , wherein said calculating of said dynamic pulp quality estimate in said signal processing unit further comprises using measured values from at least one of said at least two refiners comprises a measured value selected from the group consisting of plate gap, pulp dry content at the outlet, chip flow rate and inlet pressure. 
     
     
         16 . A method according to clam  13 , wherein said pulp quality measuring device measures the pulp quality in a latency chest.