PLS discriminant analysis with contribution plots to determine differences between parallel batch reactors in the process industry

PLS discriminant analysis, applied to a PVC polymerisation batch process, is used to determine performance differences of parallel batch reactors. Weight contribution plots of time points and of variables are used to physically interpret the modelled differences; the main time points in which deviations occur and variables that cause the observed differences are assigned. A simple step-wise procedure is suggested to implement this method in the process industry. It was found that a systematic difference between the polymerisation time of the PVC batch reactors was caused by sensor failure or due to drifting thermocouples.