Measuring and modelling of particle-fluid flow in a riser reactor

An introduction to the basics of fluidization techniques and especially the principle of a fluidized catalyst cracking (FCC) plant is given. The flow in the riser reactor of an FCC plant is essentially a two phase flow with gaseous fluid flow and particulate flow consisting of the cracking catalyst. Experimental results obtained from tracer measurements done in an FCC plant are presented Measurements indicate that a dilute phase flow is dominating the flow structure of the catalyst in the riser. Different approaches to model two phase flow are reviewed. Axial dispersion model fit is done and a simulation model is constructed in order to calculate the radial distribution of the cracking catalyst in the FCC riser. A satisfactory agreement with the experiments and the model is achieved when the slip velocity between discrete particles and the fluid is described using the Newtonian drag force. The Newtonian drag is argued to be due to turbulent fluid flow.