Boiling beds of solid particles fluidized by air are used widely in the production of polymer articles.Such beds ensure that a variety of technological processes (e.g., vulcanization, application of coatings, etc.) are carried out efficiently and in an environmentally friendly way. However, the quantitative dependences describing the expansion of boiling beds when a long body is immersed in them have not as yet been determined.By long we mean a body (fixed or moving), immersed in a boiling bed, whose dimensions are commensurate with the height of the bed in a fluidized state and, in addition, along whose whole height contact may occur with three zones of the bed -grid zone, main zone and zone above the beddepending on the distance from the gas distributor [i].It is known [i] that the process of expansion of a boiling bed with an immersed body is complex and has been little studied.In view of the diversity of the physical factors influencing this process, we deal with the one needed, above all, for the study of the behavior of expansion of a boiling bed with an immersed long body as a function of changes in the characteristic dimension of the "body-apparatus" system Do/D a (here D a and D o are the inner diameter of the apparatus and the outer diameter of the long body, respectively), depth of immersion of the body in the bed y/H 0 (here y is distance from the gas distributor to the lower end of the body; H0 is height of the fixed bed), and fluidization number F. Parameters Do/D a and y/H 0 take into account different responses of the bed (in particular, expansion of the bed) to perturbations which occur when a long body is immersed as a result of changes in the hydrodynamic parameters of the bed along its height and along the apparatus radius, other conditions remaining equal [2, 3]. Parameter F reflects the generally known fact that the primary reason for the existence of the boiling bed is movement of gas (liquid), on the velocity of which depends the nature of the process (filtration, gentle boiling, developed boiling, etc.).In the present work we experimentally determined the expansion of a boiling bed from changes in the static pressure Pst along the bed height, going upward from the gas distributor. We measured the value of Pst in a boiling bed with an immersed long body and in one without a body at identical points for identical air flow rates in the appratus.We found that, starting from the upper boundary of the bed (with further rise), the values of Pst do not change and correspond to the value of atmospheric pressure at the bed exit.On the basis of this, from the values of Pst near the upper bed boundary, we determined the height of the expanded boiling bed, i.e., its value starting from which Pst = idem.We fluidized beds of spherical 2.74 mm silica-alumina catalyst particles and particles of synthetic corundum of arbitrary surface shape with an equivalent diameter of i.i mm. The static bed height was 0.2 m and the apparatus diameter was 0.172 m. As a long body, we successively used cylinders with a hei...
