Characterizing gas and solids distributors with heat transfer study in a gas-solids downer reactor

The heat transfer behavior between the gas-solids flow suspension and a sma ll suspended surface near the distributor region was employed to study the characteristics of the gas and solids distributors with five different dist ributor designs in a gas-solids co-current downflow fluidized bed (downer) of 9.3 m high and 100 mm i.d., using FCC particles. The radial distribution s of heat transfer coefficient between the small suspended surface and the gas-solids flow suspension at several axial levels in the entrance region w ere obtained using a miniature cylindrical heat transfer probe, with differ ent types of distributors and at various operating conditions. It is shown that the effects of the distributor design on the gas-solids flow can be ch aracterized using the heat transfer techniques, given the close relationshi p between heat transfer and solids concentration. Furthermore, the radial d istributions of the heat transfer coefficient have distinct variations unde r different types of distributors. The heat transfer results indicate that the distributor structure can significantly affect the gas and solids flow pattern and flow development in the entrance section of the downer. (C) 199 9 Published by Elsevier Science S.A. All rights reserved.