DEVELOPMENT OF A NOVEL ENERGY EFFICIENT ADSORPTION DRYER WITH ZEOLITE FOR HEAT SENSITIVE PRODUCTS

Abstract

Drying is a basic operation in wood, food, pharmaceutical and chemical industry. The operation is important to enhance the preservation properties of agriculture crops and pharmaceutical products, to reduce the costs for transportation, to increase consumer convenience of food products, and to obtain desired water content in raw material feed for next unit process in industry. Currently several drying methods are used, ranging from traditional to modern processing: e.g. direct sun drying, convective drying, microwave and infra-red drying, freeze and vacuum drying. However, the current drying technology is often not efficient in terms of energy consumption (energy efficiency of 20-60%) and has a high environmental impact due to combustion of fossil fuel or wood as energy source. This work discusses on the development of adsorption drying with zeolite to improve the energy efficiency as well as product quality. In this process, air as drying medium is dehumidified by zeolite. As a result humidity of air can be reduced up to 0.1 ppm. So, for heat sensitive products, the drying process can be performed in low or medium temperature with high driving force. The study has been conducted in three steps: designing the dryer, performing laboratory scale equipment (tray, spray, and fluidised bed dryers with zeolite), and evaluating the dryer performance based on energy efficiency and product quality. Results showed that the energy efficiency of drying process can reach 70-80% in which is 15-20% higher than that of conventional dryer. Index Term— adsorption, drying, energy efficiency, zeolite, heat sensitive