Thesis Details

Thesis Title: A mathematical model to control water consumption in wet processing
Thesis Author: Robert Hammersla, Jr.
Abstract: Mill management is often faced with difficult questions such as determining the effects of changes in processing variables on subsequent quality. Generally these questions can be answered, but often the time required to obtain sufficient data to evaluate the results is prohibitive. Simulation has been shown to be of value in quickly answering these types of questions when a model is available which describes the process under study. This thesis makes available a mathematical model of the washing operation. In developing this model of washing, appropriate equations were written and tested for accuracy, and then a simulation of changes in the process variables was performed to observe their effects on final concentration. The procedure used to model the washing operation was to first write equations to explain a one-box washer. Then with certain modifications the one-box washer model was expanded to a four-box model. All variables were separated into their individual components and equation writing ended when the last variables introduced could not be defined in terms of other variables. After the equations were written, the model was tested for accuracy with mill data. The one-box model appeared to be reasonably accurate, but sufficient data to test the four-box model were unavailable. Until the data can be obtained for complete validation of the four-box model, several experiments will have to be performed by the individual mills employing this model to adapt it to their particular operation. However, assuming that the model closely resembles an actual washing operation, the simulation will give an indication of the results that a mill would expect to obtain. Future work devoted to fuller understanding of the proportionality factors will ultimately allow use of the model for multiple wash~rs without preliminary plant experiments.