Slumping bed

Fluid beds can be fired with gas and oil across the top of the slumped bed since sufficient freeboard exists with coal firing to prevent particle elutriation. Oil, gas or dual-fuel burners so arranged could also provide the means for bed preheating, especially if the flame is redirected down to the fluidization zone. 

Slumping bed When the rotation and/or collision of particles are constrained and if bu/by>0 then the shear stress is static and is simply given as... 

Glicksman LR, Yule T, Arencibia A, Pangan A. Heat transfer to horizontal tubes in a slumped bed adjacent to a fluidized bed. Proceedings of 7th Eng. Foundation Conf. on Fluidization. New York Engineering Foundation, 1992, p 813. 

To estimate the slumping motion of the kiln bed which periodically exposes a fresh, vapor saturated surface at the bed—freeboard interface must be considered. Based on Pick s second law in a bed of porosity, S, and for an effective diffusion coefficient, the mass-transfer coefficient on the bed side is... 

Figure 43. Particle accumulation in slumped zone adjacent to active bed air velocity through active region = 151 cm/s air velocity through slumped region = 7.3 cm/s numbers above heater are heat transfer coefficient in W/m2 °C after 15-30 min. (From Glicksman etal., 1992.)...

Increase in the rate of liquid feed addition and in its solids or binder content generally produces larger, stronger and more dense granules. There is, of course, an upper limit to the liquid feed rate set by increasing cohesion of bed particles and a tendency for the bed to slump or defluidize. 

For operations under more strongly fouling conditions, options have been developed to overcome the fouling problem, such as periodic or continuous withdrawal of fouled catalyst from the reactor and reintroduction of the catalyst after removal of trapped dust. The removal and reintroduction of catalyst from the catalyst slabs is easily achieved when the gas flows horizontally through vertically oriented catalyst slabs. Fouled catalyst can be removed at the bottom end of the slab by gravity and clean catalyst added at the top of the slumped catalyst bed. 

Terrigenous sediments, i.e. elastics consisting of material eroded from the land surface, are not only understood as nearshore shallow-water deposits on the shelf seas, but also comprise the deltaic foreset beds of continental margins, slump deposits at continental slopes produced by gravity transport, and the terrigenous-detrital shelf sediments redistributed into the deep sea by the activity of debris flows and turbidity currents. 

As rock fragments found within the coal bed as a result of faulting, slumping, or related disturbances... 

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