A systematic analysis of the break subsystems of a wheat flour pilot mill.

A unit operations approach was used to study the break subsystem of the wheat flour milling process. The purpose of this study was to determine the parameters of the incoming stock to a break subsystem in estimation of the particle size distribution of the stock leaving the subsystem. The incoming stock characteristics studied included the wheat commercial characteristics and the particle size distribution. The data used in this study were obtained from nine batches of commercial hard red winter wheat milled in the Kansas State University pilot flour mill. A logistic model with three constants was used to describe the cumulative granulation curve for each of the five break subsystems. When the logistic model was parameterized, it was found that the three constants of the logistic model were a function of the wheat characteristics for the first and fifth breaks. For the second, third and fourth breaks, in addition to the wheat characteristics, the independent variables of the logistic model parameters were the mean diameter (Dgw) of the incoming stock and=or its mean diameter standard deviation (Sgw). To validate the models, a brand new set of data was tested using the five empirical models developed for the break subsystems. The experimental and modelled cumulative granulation curves showed that the best result estimation was obtained for the first break, and a poor prediction was obtained for the other breaks. The models developed from this investigation are useful in education and training. The parametric models developed indicated the commercial parameters of major influence in a pilot flour mill and are expected to have similar impact in a large-scale operation. The modelling and simulation results could provide a tool for millers to analyse, optimize and improve the mill’s operation efficiency.