CHARACTERIZATION OF GAS-SOLID FLUIDIZATION AT HIGH TEMPERATURE BY ANALYSIS OF PRESSURE SIGNALS

摘要

An extensive experimental campaign aimed to study the influence of temperature on the fluidization behavior of solid materials in the presence of interparticle forces (IPFs) were conducted in a 20 cm I.D.pilot scale fluidized bed reactor.Coarse silica sand particles (dp=830 μm, pp=2650 kg/m3) were used as the bed material.Varying degree of IPFs was introduced into the otherwise fresh bed material by combustion of bituminous coal or alkali and/or alkali earth metals laden coal.In the temperature range targeted by the study (700-1000℃), impurities in the coal and alkali and/or alkali earth metals can form low melting point eutectics on the silica sand surface yielding particle cohesiveness (IPFs).Propane was then used to maintain the bed temperature and the bed hydrodynamic characteristics were monitored using high frequency (400 Hz) pressure signals.Analysis of acquired pressure signals showed that the presence of 1PFs at high temperature could drastically change the flow dynamics of gas-solid fluidized bed.It confirms that the sole consideration of variations of gas phase properties in prediction of bed hydrodynamics at high temperatures for the purpose of design and operation could introduce considerable errors.