FOULING REDUCTION CHARACTERISTICS OF A CIRCULATING FLUIDIZED BED HEAT EXCHANGER

Fouling and cleaning tests are performed for a uniquely designed fluidized bed type heat exchanger for exhaust gas heat recovery The tested heat exchanger model (1 m high, 54 mm internal diameter) is gas-to-water and is composed of a main vertical tube and additional four auxiliary tubes through which particle circulate and transfer heat. Through the present study, fouling of heat exchanger surface could successfully be simulated by controlling air-to-fuel ratios (A/F) rather than introducing particles through external feeder, resulting in soft deposit layer about 1~1.5 mm thick on the inside pipe wall. Exhaust gas temperature at the heat exchanger inlet is maintained typically 450deg.C at the gas volume rate of 0.738-0.768 CMM (0.0123-0.0128 m3/sec). According to the tested results, soft deposits are easily removed by introducing glass bead particles and also double folded heat transfer performance (in terms of overall heat transfer coefficient) could be achieved