Experimental Analysis of NC Fibers Sedimentation After Dehydration Process in Propellant Production

During the manufacture of energetic materials, the dehydration process of nitrocellulose doughs provides a residual liquid mixture consisting of water, alcohol and nitrocellulose (NC) fibers. The separation of such fibers is required for distillation of alcohol, in order to make possible its reutilization in subsequent processes. In this work, an experimental analysis of sedimentation mechanisms of NC fibers contained in the fluid mixtures from nitrocellulose plants, is presented. The goal of the work is to obtain the time periods needed for complete sedimentation of these solid fractions (NC fibers). Cylindrical tanks with vertical or horizontal orientation are considered in this study, and the results obtained for both tank configurations are compared. From the experimental observations about sedimentation mechanisms of solid fraction in these fluid mixtures, recommendations about optimum times for NC fibers removal are proposed. These optimum times should be assumed as basic guidelines for scheduling and execution of the distillation process, due to its high influence on minimization of the overall operational costs for this process. Great discrepancies were registered between sedimentation times of NC fibers in vertical or horizontal tanks, with reductions in sedimentation rate of until 40% for recipients located in vertical orientation.