A one-dimensional plug-flow model of a counter-current spray drying tower

•A multiphase plug-flow model for a counter-current spray drying tower is developed.•A semi-empirical slurry droplet drying model is integrated with the plug-flow model.•The coupled 1st order ODEs are solved using the iterative shooting method in MATLAB.•The model is applied to simulate detergent slurry spray drying in a pilot plant.•The model predictions are in reasonably good agreement with the experimental data. A one-dimensional numerical model for a detergent slurry drying process in a counter-current spray drying tower is developed for the prediction of the gas and droplet/particle temperature profiles within the tower. The model accommodates droplets/particles over a range of sizes. A semi-empirical slurry droplet drying model is integrated with a counter-current tower simulation based on mass, energy and particulate phase momentum balances in order to calculate the drying rate and the particle residence time within the tower. The coupled first order ordinary differential equations for the two phases are solved numerically using the iterative shooting method in an algorithm developed within MATLAB. The predictions of the numerical model are compared with industrial pilot plant data. The results are found to vary significantly with the specified size distribution of the droplets. Despite the simplicity of the model in ignoring the coalescence, agglomeration, wall deposition and re-entrainment, the model gives reasonable agreement with the experimental data.