Maximum spoutable height

Littman H, Morgan III MH, Vukovic DV, Zdanski FK, Grbavcic ZB. Prediction of the maximum spoutable height and the average spout to inlet tube diameter ratio in spouted beds of spherical particles. Can J Chem Eng 57 684-687, 1979. 

The presence of the draft tube in the reactor allows to achieve other desirable features. In conventional spouted beds, the spout (jet) is in continuous contact with the annular solids over the entire height of the bed and, to achieve a stable operation, it must be able to support the surrounding annular bed. To provide this support, the spout must be at a greater pressure than the annulus. Because of this pressure difference, there is continuous percolation of gas into the annular region and, if the bed is too deep, the spout can easily collapse. The bed height at which this transition occurs is termed the maximum spoutable height (Mathur and Gishler, 1955). The presence of the draft tube removes this limitation. 

Experiences with the pilot plant at very high temperatures (above 600°C) have indicated some limitations of the above described spouted bed reactor configuration. Firstly, the maximum spoutable height decreases with increasing temperature, as... 

Spouting cannot be maintained once the bed height exceeds a certain level, coim monly known as maximum spoutable bed depth, Hm. At Hm, the spout starts to collapse and the bed starts to change from a spouted bed to a fluidized bed. As indicated in Eq. (9.67), the minimum spouting velocity increases with an increase in the bed height. Consequently, (7msp achieves its maximum at Hm. The maximum value of the minimum spouting velocity can be related to the minimum fluidization velocity by... 

The classic or conventional spouted bed (CSB) is a cylindrical vessel with a conical bottom fitted with an inlet nozzle for the introduction of the spouting air (drying medium). This device suffers from limited capacity due to the maximum spoutable bed height and inability to scale up the apparatus beyond... 

The maximum value of the minimum spouting velocity, occurs when the bed height is at the maximum spoutable bed depth or... 

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