Optimisation of the Energy Consumption in the Pulp Refining Operation

In paper industry, the pulp refining operation enab les manufacturing a wide range of fibrous suspensions (pulps) which induce different paper grades. We propose in this paper a methodology for optimizing a refining insta llation. A standard drainage test (°SR) characterizes in paper industry the refined p ulp. For the papermakers, the control of the °SR is consequently of primary importance si nce it is correlated with the end-use paper properties. In this research, refining trials are carried out on bleached softwood Kraft pulp using a laboratory disk refiner running in a batch mode and low consistency (2% to 6% of mass solid fraction). The refining kin etics is analyzed by considering the evolution of the °SR function of the net mass energ y consumed. All the curves exhibit an S-shape. At the same net mass energy consumed, the kinetics curves may differ considering the applied net power. Instead of the n et power, a more general concept of the refining intensity is used here the net tangent ial force per crossing point. 4 values of this intensity enable differentiating the experimen tal trials. It has to be noted that 6 points of net mass energy consumed are considered per intensity. For the covered range of intensity, between 1.4 and 4.3 N, the quickest r efining kinetics is obtained for (44.5 +/- 1) °SR which minimizes the required energy cons umed at 3.1 kWh/(t.°SR) for a softwood pulp. This numerical value is 5 to 6 times less than the industrial ratio 15-20 kWh/(t.°SR) classically encountered in industry for printing and writing paper grades.