Correction of residence time distribution measurements for short holding times in pasteurization processes

Abstract

Abstract When in-line cells are used for obtaining residence time distribution (RTD) data from systems with short residence time, the signal distortion caused by the cell can compromise the results. A procedure to correct such distortion using convolution of signals in the time domain is proposed. First, the RTD of the cell is characterized, and then the E-curve of an RTD model is convoluted with the cell curve. The convoluted E-curve is fitted to the experimental data by adjusting the mean time and the model parameter. The procedure is demonstrated using a pilot scale pasteurization unit with two heaters, one cooler and six options of holding tube. Pulse experiments were performed, E-curves were obtained for each process step and five RTD models were tested. The convolution procedure was successful in removing the distortion caused by the detection cell, which was very significant for the holding tubes.