泡鐘塔の液側物質移動速度について

抄録

Owing to the stagewise contact which takes place in bubble-cap plate columns, performance data for suchequipments are usually expressed in terms of plate efficiency. A considerable number of investigations on plate efficiencies ever reported have failed to give a coherent picture, because of a great many unknown factors usually involved in them.
The present work has been performed for the purpose of obtaining an expression for predicting the liquid phase mass transfer rate for bubble-cap plate columns. The data presented are derived from the experiment on the absorption of pure CO₂ by city water in a 10 in. I.D. steel column containing one plate and a varying number of caps, from 1 to 7, with 2 and 3 coming in between for the runs, respectively. The bubble-cap is 40mm in diameter, 40mm in height and contains 16 (10.5mm by 3.6mm) rectangular slots per piece. The general layout of the equipment is shown in Fig. 1. When correlating the data thus obtained, a dimensionless equation has been obtained from the basic differential equation (for liquid phase mass transfer at isothermal absorption in a tower-type absorber), as follows: NHL=f(ReL, Se, NX, NZ)
where: NHL=HL/(μμ²/ρρ2g)1/3, ReL=ρuX/μ, Sc=μ/ρDL
NX=X/(μμ²/ρρ²g)1/3, and NX=Z/(μμ²/ρρ²g)^1/3
The liquid film, H.T.U., HL, is calculated from the observed values of NL and the length of the path of liquid flow across the plate. In calculating the true Reynolds number of liquid, it is necessary to have on hand the data on the wetted perimeter or the contact area between gas and liquid flowing on the plate, but since it is impossible to obtain reliable data of such kinds, the approximate Reynolds number of liquid are employed. The one used in this work is based on the depth of clear liquid on the plate and the minimum space between the caps at the center of the plate without gas flow. Because of this approximation, the Reynolds number of gas must also be taken into consideration as one of the necessary operating variables. In this case the Reynolds number of gas employed is calculated from the slot gas velocity and the hydraulic mean diameter of the slot.
A general correlation applicable to the bubble-cap plate columns is presented as within a range of 20% (cf. Fig. 6), but the effect of NZ is not satisfactorily established by this only and further investigation will have to be conducted. The data obtained by Walter and Sherwood3)and Gerster et al.1) are plotted. The data of Gerster et al. show satisfactory agreement with the authors' and the effect of liquid viscosity on HL observed by Walter and sherwood agrees with the effect predicted frotn the present investigation.