Hydrodynamic characteristics of a rotating spiral fluid-phase contactor

Abstract

ReuseThis article is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs (CC BY-NC-ND) licence. This licence only allows you to download this work and share it with others as long as you credit the authors, but you can't change the article in any way or use it commercially. More information and the full terms of the licence here: https://creativecommons.org/licenses/ Rotating spiral channels enable any two immiscible fluid phases to flow counter-currently in parallel layers allowing independent control of phase flow rates and layer thicknesses. This opens the possibility of application over the full range of fluid contacting operations, including distillation, absorption, extraction and multiphase reaction with separation. A device has been developed that enables wide-ranging experimental studies to support model refinement and design of first-generation applied devices. In this first work with the new device hydrodynamic characteristics are studied for gas-liquid systems as functions of phase flow rates, rotation rate and liquid viscosity. Measurement of the heavy phase layer thickness, using image analysis based on the Young-Laplace theory for interface shape, and measurement of volume flow rate of each phase and pressure and temperature in the spiral channel allows rigorous comparisons with an existing 'wide-channel' model relating flow rates and layer thicknesses to phase properties, geometry and rotation rate. The measured thickness of the heavy-phase layer is predicted well by the wide-channel model at high rotation and phase flow rates, where the deviation from a uniform layer thickness due to menisci at the channel end walls and interface tilt from gravity are small. At low rotation rates, where significant meniscus height and tilt develop, the layer thickness is over-predicted by the wide channel model. The sub 20 µm heavy-phase layer thicknesses measured suggest operation at optimum thickness is possible with the rotating spiral over a wide range of phase and solute systems.

CO2 absorption using diethanolamine-water solutions in a rotating spiral contactor

“…At the relatively low gas flow rates that will be required, the liquid layer is largely unaffected by the shear stress exerted by the gas at the phase interface [1]. Consequently, force on the liquid from the shear stress at the channel wall alone must balance the body force associated with centrifugal acceleration.…”

“…The principal difference from the apparatus described in MacInnes and Zambri [1] is the insertion of the sensor to measure CO 2 composition. Depending on the configuration, all or part of the outlet gas flow is passed through an infra-red sensor (CO2S-FR-X, SST Sensing…”

“…The apparatus used in this work was first reported in MacInnes and Zambri [1]. Briefly, two fluid phases are transferred continuously to and from the rotating spiral channel through pairs of lip seals to make flow connections with the rotating unit.…”

“…All experiments reported here use a rotation rate of 3200 rpm with the liquid outlet to atmospheric pressure for which conditions the estimated temperature and pressure in the spiral are 312 K and 1.8 bara absolute. This rotation rate is sufficiently high for the end menisci to have negligible influence on liquid layer thickness so the wide channel model [2] gives a reliable representation [1]. separate needle valves were used to span the gas flow range.…”

“…MacInnes and Zambri [1] describe a rotating spiral device for carrying out fluid phase contacting and study its hydrodynamic characteristics for gas-liquid contacting.…”