Mechanism of a twin-fluidized-bed air preheater
A new type of air preheater, twin-fluidized-bed air preheater, is presented. It is mainly made up of two parallel gas-solid bubbling fluidized beds at different temperatures. The two fluidized beds are connected by two non-mechanical L-valves. The hot and cold gases flow through the hot and cold beds respectively. The heat transfer from the hot to the cold gas is accomplished via the solid particle circulation between the two fluidized beds. The two L-valves constitute the passageway of the particle circulation. The particles are heated in the hot bed, pass through L-valve 1, cooled in the bold bed, and then return to the hot bed by means of L-valve 2 to be heated again. This performs one period of circulation. The circulating particles enter and leave the L-valves in the form of moving packed bed, hence the circulation ratio is very high. The heat transfer process of the air preheater is analyzed. At both sides of the air preheater the heat transfer takes place by fluidized bed gas-solid convection. Because of the favorable gas-to-solid heat transfer properties in the fluidized beds, the local thermal resistances of both sides of the air preheater are lessen simultaneously, and the overall heat transfer coefficient of the air preheater is significantly improved. Furthermore, no tubes are immersed in the twin-fluidized-bed air preheater; therefore, there are no erosion and fouling problems and the cost is low. Experimental apparatus is established. The experimental comparison results show that the twin-fluidized-bed air preheater has a larger heat transfer capacity and a smaller required volume than the rotary-type regenerative air preheater. The measures taken to reduce the pressure drop in the air preheater are also discussed.
- Research Organization:
- Huazhong Univ. of Science and Technology, Wuhan Hubei (CN)
- OSTI ID:
- 20006761
- Report Number(s):
- CONF-990534--
- Country of Publication:
- United States
- Language:
- English
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