The concept and use of a rotating chimney for compressing rotating fluidized beds is theoretically and experimentally studied. A rotating chimney is shown to drastically increase the operating flexibility of rotating fluidized beds and to allow a significant improvement of the particle bed uniformity. In particular, the rate of solids losses via the chimney can be reduced and bubbling can be suppressed by compressing the rotating particle bed. (c) 2009 Elsevier B.V. All rights reserved.