A circulating fluidised bed

CFD and experimental studies of solids hold-up distribution and circulation patterns in gas–solid fluidized beds

“…La Nauze [63] studied the solids circulation pattern by using particle tracking method for a 0.3 m diameter air-sand internally circulating fluidized bed (with a draft tube). It was observed that the solids flow upwards through the draft tube and downward in the annulus.…”

Control mechanisms of fluidized solids circulation between adjacent vessels

“…These compact systems have the following advantages: Easy to obtain circulation Stable circulation rate of solids Real operating flexibility A great deal of experimental results have been published so far (Yang and Keairns, 1975,1978, 1983LaNauze and Davidson, 1975;LaNauze, 1976;Hofbauer, 1983; authors found that the circulation rate of solids could be controlled by the aeration rate in the upflowing compartment and by the area of the communication orifice. They developed an equation, based on the analogy of the flow of a liquid through an orifice, which could explain the results obtained with the fourcompartment cold model and predict the value of the circulation rate of particles within 40%.…”

“…The friction of particles against the vertical walls in the The contraction of the flow of the gas-solids mixture in the Some authors found the first one to be predominant (La-Deriving equations for the driving and resisting forces Drawing the consequences for the experimental program Nauze and Davidson, 1975, andLaNauze, 1976), while others attributed the most efficient effect on the control of the circula-Operaring principfe ofcircufaring tion rate of solids to the second one (Kuramoto et al, 1986). In…”

“…They are used mainly for the gasification of coal and biomass, and they are generally made of several fluidized compartments. Examples of such concepts are the draft-tube (Yang and Keairns, 1975, 1978, 1983LaNauze and Davidson, 1975;LaNauze, 1976;Hofbauer, 1983;Judd et al, 1983Judd et al, , 1986Escudero et al, 1985, andButton andDelcoigne, 1985), the two-compartment auto-circulating fluidized boiler (Ndenge, 1985) and the fourcompartment reactor invented by Kunii (Kuramoto et al, 1981. These authors showed the existence of a driving force, of two kinds of resisting mechanisms, and of a gas bypass phenomenon.…”

Heat transfer process in gas–solid fluidized bed combustors: A review

“…Heat transfer in internally circulating fluidized bed combustors (ICFBC). An internally circulating fluidized bed (ICFB) is a type of fluidized bed with a centrally located draft tube [51][52][53][54] or a plate [55] that divides the bed into two or more sections and thus promotes solid circulation within a single vessel. ICFBs have several advantages over CFBs, such as reduced height and construction costs, compact size and comparatively small heat loss from the reactor [54].…”