Internal Heating Effect and Application of Microwaves with Fluidization of Electrically Conductive Particles in the Ceramic Drying Process

• Published in: Developments in Chemical Engineering and Mineral Processing 2002, Vol.10 (3-4), p.381-400
• Main Authors: Itaya, Y., Okouchi, K., Uchiyama, S., Mori, S., Hasatani, M.
• Format: Article
• Language: English
• ISSN: 0969-1855; 1932-2143
• DOI: 10.1002/apj.5500100410

In the ceramic drying process, it takes a long time to completely remove internal moisture from molded ceramics due to large resistance of internal migration. Microwave heating is an effective internal heating method and will promote the moisture movement rate inside ceramics due to the elevation of vapor pressure. The effect of internal uniform heating on the ceramic drying behavior is first studied by theoretical analysis. The effectiveness and problems of drying of a slab heated by microwaves were evaluated experimentally and compared with hot air heating. The drying proceeded successfully and quicker than hot air heating when the internal temperature could be controlled below 380 K, by introducing intermittent heating or low power irradiation of microwaves. Additionally, a technique for improving uniformity of the microwave field by fluidization of electrically conductive particles was proposed. The distribution of the microwave field became successively uniform by the diffuse reflection of microwaves in a fluidized bed of plastic foam particles wrapped in aluminum foil.