FLOC Size Distributions in Dry Formed Webs, 1998 Engineering Conference Proceedings

Floc size distributions and some characteristics of formation in the product web for two pilot plant dry forming systems are reported in this work. In both systems a relatively high quality web was produced allowing for floc size measurements by (i) visual inspection and (ii) image analysis methods. One of the forming systems involved a high velocity trajectory-type process in which floc size was measured by three observers using visual inspection procedures. The other process was a lower velocity, fluidizing system in which floc sizes were estimated by image analysis.

The floc size distribution for both processes were found to be log-normally distributed for most experimental conditions. In the high velocity forming system the webs were formed with the pulp projected vertically downward to the forming wire with dispersion jets at the top of the forming head. In the fluidizing system, the pulp fiber was transported upward to the forming wire with dispersion jets in the bottom of the forming head. A smaller floc size as measured by the arithmetic mean and geometric mean values was observed in the fluidizing system but the percentage of the total web area covered by flocs was similar in both systems.