Transient modelling of the combined gas-particle flow in the freeboard of a fluidized bed reactor

Transient freeboard flow simulations have been performed. A dedicated simulation model has been developed based on the FLUENT 3.03 code. This freeboard flow model is presented in this paper. Special attention is paid to the modeling of the bubble eruptions and their impact on the freeboard flow. The transient freeboard flow which develops from these bubble eruptions is simulated. Typical freeboard flow phenomena such as the downflowing wall layer and the height of rise of large particles, which were not well understood up to now, are explained from the present simulations. The freeboard solids flow, both in vertical and in horizontal direction is concluded to be largely determined by the bubble eruption process.