NEW FIBEROPTIC METHOD FOR MEASURING VELOCITIES OF STRANDS AND SOLIDS HOLD-UP IN GAS-SOLIDS DOWNFLOW REACTORS

A novel, reflective-type fiber-optic sensor was used to assess the siz es of certain types of clusters, called strands, as well as strand vel ocity and solids hold-up in gas-solids downward flowing suspensions. T his sensor was employed successfully in a series of experiments perfor med in a downflow, acrylic cold model reactor. Cluster (strand) veloci ties in the range of 0.6 to 3.9 m s(-1) and solids hold-up between 0.0 02 and 0.007 were measured for solids with a mean particle size of 65 mu m and for calculated strand lengths up to 583 mu m. Other parameter s, such as solids-gas slip velocity, were also assessed and a model ba sed on the fluid-dynamic characteristics of strands was developed. It is demonstrated that this kind of model allows the development of a re lationship between solids hold-ups and strand dimensions and that it p rovides good accuracy in downflow solid suspensions.