Process Equipment and Plant Design
Normally, the ratio of the total riser area to the tower cross sectional area (for bubble cap towers of diameter more than 3 ft) is around
The dimensionless ratio of liquid gradient to pressure drop head caused by the bubble cap assembly should be less than 0.4
The pressure drop due to the caps & slots and the static submergence should be as high as practicable for reasonable operation
Tendency towards stable operation is increased by increasing the skirt clearance of the caps, lowering the rate of liquid flow per unit plate width or increasing the spacing between the caps