Particle morphology of alkali metal chloride salts in induction heating based pulsed spray drier: Experimental analysis and ANN prediction

Hygroscopic nature of alkali metal chloride salts makes attaining mono-sized dried particles from their aqueous precursor solution an engineering challenge for conventional co-current or counter-current spray driers. Conventional spray driers offer better thermal utilization in either the spray zone or dried particle zone depending on their configuration viz. co-current or counter-current, respectively. In this work, an alternative prototype named induction heating based pulsed spray drier (IH-PSD) is proposed to obtain dry alkali metal chloride salt powders with narrow particle size distribution. Laser diffraction analysis is carried out for initial droplet size distribution whereas scanning electron microscopy and sieve shaker analysis is carried out for studying the particle morphology and particle size distribution of dried powder for all the selected salts. The resultant particle properties emphasized in the present work are the dried particle to initial droplet diameter ratio and the wet basis moisture content. It has been observed that the ratio of mean volume diameter of dried particle to sauter mean diameter of initial droplet lies in the range of 0.4–3.6 meanwhile the wet basis moisture content of dried powder lies in the range of 1.4–3.6 for the selected salts. Artificial neural network (ANN) model is applied for inferring the influence of IHPSD process parameters on the above mentioned dried particle properties and satisfactory convergence with experimental values has been achieved. Comparative plot for experimental and ANN predicted values of dried particle to droplet diameter ratio d43pd32sol [-] and wet basis dried particle moisture content χwp [%] of alkali metal chloride salts in induction heating based pulsed drier (IH-PSD) prototype. Spray drying prototype coupled with Induction heating and mechanical pulsation Scanning electron microscopy for morphological study of spray dried particle Laser diffraction for initial droplet size distribution analysis Sieve shaker experiments for size distribution analysis of spray dried particle Artificial neural network for prediction of droplet to dried particle size ratio