Gas holdup in a gas-liquid-fiber semi-batch bubble column

Modeling Gas Holdup in Gas−Liquid−Fiber Semibatch Bubble Columns

“…On the basis of the above analysis, the gas holdup model for this flow regime can be assumed to be where g ( C , L ) represents the terminal bubble rise velocity V 0j . It is assumed that g ( C , L ) can be described by a functional relationship involving N and N f , i.e …”

“…semibatch bubble column with a perforated plate gas distributor with A = 0.49% . Su 15 showed that the models work very well provided that the coefficients are altered to account for column diameter effects; more details are provided elsewhere …”

“…Su and Heindel 12 showed that the same crowding number for different fiber suspensions does not produce the same gas holdup, and this phenomenon is attributed to the fact that the crowding number exaggerates the effect of fiber length on gas holdup, especially when the fibers are long. Su 15 argued that it might be more appropriate to combine the crowding factor with another (other) quantity (quantities) to describe the fiber effect on gas holdup.…”

“…On the basis of the above analysis, the quantity C d /d b is a function of U g , N f , and N. Hence, eq 10 can be rewritten as Su 15 found that the combination N a N f b is a reliable parameter for describing the effects of fiber mass fraction and fiber length and proposed a gas holdup model in the form The coefficient a 1 and exponents a 2 -a 4 in eq 12 are…”

“…The percent uncertainty in the superficial gas velocity measurements is estimated to be ±2−4%, and the absolute uncertainty in the gas holdup is estimated to be Δε = ±0.006−0.008. More details of the experimental procedures can be found in Su and Heindel 14 and Su 1 Cellulose Fiber Properties hardwoodsoftwoodBCTMP a wood species eucalyptus 65−75% northern black spruce, 20−25% jackpine, 5−10% balsam fir northern pine particle average fiber length (mm) 0.69 1.2 0.8 length-weighted average fiber length (mm) 0.78 2.31 1.91 coarseness (mg/100 m) 6.9 13.1 29.5 number of fibers per gram (millions) 21.4 6.37 4.25 a Bleached chemithermomechanical pulp. …”