Using Electrical Capacitance Tomography to Investigate Gas Solid Contacting

Robert B White

CSIRO Minerals Box 312 Clayton South Victoria 3169 AUSTRALIA

ABSTRACT

This paper provides a background concerning the interaction of gas and solids and emphasises that particle technologists have classified behaviour into several distinct groups. Differences in behaviour between each group can be attributed to the relative magnitude of inter-particle adhesion forces. In general, finer particles are more greatly affected and it is usually difficult to predict the exact transition from one type of particle behaviour to another.

An ECT system has been shown to be useful in observing differences in particle behaviour in a bubbling fluidised bed. An image analysis technique is further described that utilises the construction of solids concentration profiles at three key values, x=0.2, x=0.5 and x=0.8, which have been identified as important solids concentrations in a new Bubble Structure Model. Significant differences in the bubble structure are show to result when the concentration of fine particles is slightly increased in a bubbling fluidised bed. Changes of this type would seriously alter the gas solid contact efficiency in the fluidised bed, which would significantly influence selectivity of in-bed catalytic reactions and gas residence time.

Keywords Electrical capacitance tomography, gas-solid contact, particle behaviour, bubbles