Simulating Textile Padding with Vacuum Extraction

Abstract

Mass balance equations have been solved to simulate textile padding followed by vacuum extraction and recycling for seven equipment configurations. These equations include five parameters describing a number of perturbations that change the con centration of the chemical solution being applied: evaporation of the solution under vacuum, incomplete recovery of the chemical after vacuum extraction, preferential absorption of the chemical or of water from the applied solution before the pad nip or between the nip and the vacuum extractor, hydrolysis of the reactive group of a dye or chemical, and desorption of water or chemical already present in the fabric being treated. Methods for determining numerical values for the parameters describing these effects are given. In addition, the model also includes bath overflow and deviation of the extracted solution to a recovery unit. A number of typical process simulations are given, demonstrating time dependence and magnitude of concentration changes for single or combinations of effects. Since the conditions for steady-state operation are easily calculated, the required quantity of chemical in the fabric can be maintained constant from the start of the process.