An experimental study of the effect of dump packing on wall to fluidized bed heat transfer

Abstract

AbstractThe improvements in the performance of gas‐fluidized beds to be gained from the introduction of baffles or packing pieces have been discussed in the literature. These include higher conversions in chemical reactions(1), reduction of freeboard necessitated by fluctuations in bed height(2) and the possibility of operating with larger length to diameter ratios(3). In the case of wall‐to‐bed heat transfer, however, a preliminary investigation(4) into the effect of fixed packing in a 4‐in. column indicated that the rate of heat transfer was in most cases adversely affected by the presence of packing because of the restriction of particle movement within the bed. This was certainly true in the case of packings of closed structure such as solid spheres, although the data suggested(4) that heat transfer in beds containing screen mesh packings of open structure may exceed that in unpacked beds in some cases.The work described herein is a quite comprehensive experimental investigation of the effect of many types of dump packings on the rate of wall‐to‐bed heat transfer. Several commercially available packings as well as cylindrical screen packings produced in this laboratory were employed. A 12‐in. diameter bed was used so that the work would give an indication of the effects occurring in larger‐scale equipment.