Minimum Circulation Velocity in a Spouted Bed Apparatus with Draft Tube

Abstract

Measurements of spouting characteristics were carried out in an apparatus consisting of two conical sections connected to a cylindrical section. Inside the lower conical section a draft tube was fixed. Results of minimum circulation velocity were obtained for an apparatus equipped with a draft tube of different inside diameters and lengths for different kinds of particles as well as for different static bed heights. Experimental data have been further analyzed to develop new correlations.

Operating and Peak Pressure Drops in Conical Spouted Beds Equipped with Draft Tubes of Different Configuration

“…In fact, the inlet diameter should be smaller than 20–30 times the average particle diameter in order to avoid a slugging regime and achieve spouting status. Draft tubes are used to achieve stability out of this range, but they change the hydrodynamics and solid circulation rate of spouted beds. − The lower conical section of the contactor performs differently when the draft tube is used and depends largely on the bed geometry, draft tube diameter, length of the entrainment zone, and operating conditions. − ,− …”

Minimum Spouting Velocity of Draft Tube Conical Spouted Beds Using the Neural Network Approach

“…It is well known that to properly predict the behavior of a system by the MLP network, a rather large amount of experimental data points is essential , . From previous works published in the literature, it can be concluded that the minimum spouting velocity in conical spouted beds equipped with a draft tube is affected by different parameters, such as the acceleration of gravity, the gas viscosity, the particle diameter, the bed cone angle, the gas inlet diameter, the static bed height, the draft tube diameter, the entrainment zone length, and the length of the tube , , . The mentioned geometric factors are illustrated in Fig.…”

Study on mass flow characteristics of fluidized bed with a circulative accelerating tube

“…Su et al [10] analyzed the effects of operating conditions and geometrical parameters on the flow behavior, and found that the minimum spout-fluidizing velocity increases with increasing the length of entrainment zone and the draft tube diameter, but it decreases with the increasing of fluidizing gas flow rate and static bed height. However, Kmiec et al [1] showed that the minimum circulation velocity is dependent on the static bed height and on the level of the upper edge of the draft tube based on their apparatus. Wang et al [11] on the other hand, studied the flow behavior of particles in a two-dimensional spouted bed with a draft tube using a continuous kinetic-friction stresses model.…”

“…In addition, in many applications of fluidized beds, extract thermal energy is required, leading to demands of specified design of reactor [2]. Therefore, finding new reactor more energy-efficient is an important factor in the proper design of industrial fluidized beds [1][2][3]. Developed by School of Technology, Beijing Forestry University [4], the annular fluidized-bed reactor combines a cylinder furnace into a fluidized-bed, which is also encircled by a cylinder vessel, as shown in Fig.…”

“…Many companies look for new constructions of fluidizing apparatuses due to the increasing demands regarding output and quality of products and new regulations for environment protection [1]. In addition, in many applications of fluidized beds, extract thermal energy is required, leading to demands of specified design of reactor [2].…”