(260e) Particle Velocity Fluctuations of Cork Particles in the Riser of a CFB

Granular theory is the analogous theory for discrete particles as the kinetic theory of gases is for gas molecules. Eulerian- Eulerian simulation codes predict granular temperature and various transport and thermodynamic properties based upon granular temperature. Tests were conducted in a cold flow model of a circulating fluidized bed gasifier to gather particle velocity data used in calculating granular temperature and overall mixture fluctuating energiy. Similitude analysis was applied to to a high pressure transport gasifier to obtain a system operating with air nominally at atmospheric pressure and cork particles approximately 1mm in diameter. Particle velocity measurements under various operating conditions were obtained with an LDV system. Measurements were taken in the riser at locations near the wall and at penetrations up to 13mm depending on the optical visibility. At the wall, the good visibility led to data with enough character to define clusters and the associated granular temperature within the clusters. The intracluster granular temperature is about one twentieth the magnitude of the overall mixture fluctuating energy at the wall. The paper also presents mixture fluctuating energy as a function of the penetration distance in from the wall. The overall mixture fluctuating energy for the cork system at these operating conditions ranged between 0.6 and 0.9 m2/s2. A surface map of granular overall fluctuating energy as a function of load ratio and penetration from the wall is provided. Maximum energies appear in the annulus 3 to 5 mm from the wall.