HYDRODYNAMIC BEHAVIOUR OF PULP SUSPENSIONS IN - PAPER: MAKING

Abstract

The flow of pulp suspensions has been an area of interest for many years The studies relate to understanding of the flow behaviour ,floc formation mechanism and behaviour of pulp suspen-sions with respect to flow variations/velocity variations and consistency variation-s.The available data and correlation are mostly for long fiber softwood pulps. There is practically no data available on the behaviour of'nonwood pulp suspensions flow in pipe lines.Chapter-I gives a review of the existing literature on flow behaviour of pulp suspensions with emphasis on under-standing of the general behaviour of flowing suspensions. The rising energy prices have added greater stress on the development of design procedure for nonwood systems,which will make design of pipe lines more accurate and thereby ensure proper energy utilisation. It is with this aim that the experiments were planned to generate data on pressure drop in pipe lines carrying nonwood pulp suspensions.Chapter-II deals with the fabrication of the test loop for conducting experiments. The discussion of the data generated for the three nonwood pulp suspensions in the nor-mal range of consistency variation (0 < C < 1.5% )and in normal range of velocity variation (0-2.5 m/s) is described in Chapter - III. The experimentally obtained data are compared with the predicted data using recommended correlations from literature for softwoods. The recommended correlations are modified for predicting the pressure drop behaviour of non wood pulp suspen-sions in horizontal pipelines. In many of the South East Asian countries nonwood fibers have become a major fiber source, and the design of pipe lines carrying nonwood fibers has essentially been on the understanding of softwoods. This has generally tended to give only approximate design procedures. Chapter - III also details the recommended correlation for softwood as well as the modified correlations for nonwoods. An approach based on the analysis of friction factor data is attempted to correct the water friction factor terms using the stock consistency, freeness and average fiber length as parameters to predict the friction factors for pulp suspensions.