A Mathematical Model for Determination of Effect of Temperature, Diameter and Moisture Content of Droplet on Efficiency of an Industrial Spray Dryer

Spray dryers are one the most applicable dryer in chemical industries. In spite of different theoretical researchs on spray drying, industrial dryer performance is still a considerable subject for scientists. In this investigation, at first, a mathematical model of a spray dryer was persented and then, the model was applied on an industrial case (Paxan Co.) with presentation of basic relations and equations. Thus, variation of feed temperature, droplet diameter and humidity versus time and also, effects of feed temperature and nozzel orifice diameter on droplet distance in vertical and horizental axes in the spray dryer tower were investigated. The obtained results from mathematical model and practical data show that effect of droplet humidity on outlet gas depends on contact time between droplet and gas. In contact time more than five seconds, higher temperature of feed causes more decrease of outlet gas temperature. In enough contact time, diameter of droplets with high temperature can be less than droplet with low temperature. Also, the nozzle with 3.5mm diameter produces low diameter droplet and decreases vaporization load of tower. According to the results, nozzle feed temperature doesn`t affect on gas temperature at the beginning of gas entry. The comparison between model results and pactical data shows that this model satifies the data very well.