Energy Considerations in the Beating of Pulp

Abstract

The incentive to intensive research on the development of radically new beating principles lies in the magnitude of the difference between the energy actually expended in beating and what, under the most ideal conditions, would be needed to modify the fibre in the desired way. Accurate information on the efficiency of existing beating processes does not exist. After a review of some of the estimates of beating efficiency, this paper presents discussions of the energies required in idealised mechanisms to produce certain modifications of the fibre. Idealised mechanisms have been invoked for the purpose of obtaining estimates of the order of magnitude of the power reduction that might be effected through the development of new beating principles. An analysis of the energy and force required to peel basic cellulosic filaments from a fibre, as a function of angle, is presented. This analysis shows that the probability of large-angle fibrillation is much greater than that for small-angle peeling. Estimates of the energy requirement are presented for the development of specific surface through fibrillation of the fibre surfaces, loosening of the internal structure of the fibre and for fibre cutting. It is concluded that a tremendous gap exists between the level of energy now expended in beating and refining and what would be consumed in nearly ideal processes.