The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering
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May 13-17, 2007
Solid flow through the loop seal of a circulating fluidized bed (CFB) was studied by investigating the effect of the horizontal passage length on solid flow through the loop seal. This was done by investigating the effects of aeration on the inter-particle friction forces, the effect varying horizontal passage lengths had on the overall solid flux around the CFB loop and on the pressure drop across the passage. The division of air flow through the loop seal was also investigated in order to determine how the solids were driven through the loop seal. It was found that for a measurable amount of solid flow to occur, a minimum aeration was required, in excess of the minimum fluidizing velocity of the particles. As horizontal passage length increased the minimum aeration required also increased. As well the maximum obtainable solid flux decreased with increasing passage length due to the increased resistance in the longer passage. The increased resistance to solid flow through the passage was seen in the increasing pressure drop per unit length across the passage, as the passage length increased. This was a result of an area of stationary solids near the end of the horizontal passage that constricted the flow of solids and got larger as the passage length increased. At low solid flow rates the supply chamber aeration was split, such that the velocity of air in the supply chamber or the stand pipe remained below the minimum fluidization velocity with the remaining flow conveying solids through the horizontal passage. At high solid flow rates all of the supply chamber aeration flowed into the horizontal passage along with an amount of air entrained by the solids falling down the standpipe.
James W. Butler and Prabir Basu, "Effect of Horizontal Passage Length on Solid Recycle Through a Loop Seal in a Circulating Fluidized Bed" in "The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering", Franco Berruti, The University of Western Ontario, London, Canada; Xiaotao (Tony) Bi, The University of British Columbia, Vancouver, Canada; Todd Pugsley, University of Saskatchewan, Saskatoon, Saskatchewan, Canada Eds, ECI Symposium Series, (2007). http://dc.engconfintl.org/fluidization_xii/17