Wood chip fiber flow rate control and TMP refining energy saving

TMP (Thermo Mechanical Pulping) is the most energy intensive process in the pulp and paper industry, about 75% of the total energy of a TMP plant is consumed by the refining process. In a typical mill under normal operating conditions, up to 30% of the disturbances in the pulping process can be explained by chip variations. In this paper, the statistical analysis of the refining processes of the mills data has demonstrated that the chip basic density stabilization could result in 3.4 - 6.4% of refining energy saving. The laboratory scale experiment and its mathematical model simulation has revealed refining energy saving is about 6.3% while the standard deviation of wood chip density reduced from 12 to 7 (kg/m3). Finally, the mill real time instrumentation and trial have shown that the stabilisation of wood characteristics, especially chip basic density can reduce the total refining energy by at least 2%.