Fluidised homogeneous

Fig. 17.7. Fluidised bed adsorption of G3PDH from milled yeast homogenate onto zirconia-silica Cibacron Blue. The feedstock (20% w/v) was fed to the bead mill at a rate 4.05 dm3-h 1, which corresponded to a linear flow velocity of 250 cm-h 1 within the BRG contactor with a settled bed height of 21 cm. The disrupted baker s yeast homogenate from the bead mill was applied to the integrated fluidised bed directly and terminated when C/Ca = 0.65.

All the model systems investigated by Bisschops et al. fell within the completely homogeneous fluidisation regime modelled by Gibilaro and Hossain126 . With the low-g rotor and... 

In liquid-solid systems, and for gas-solid systems of small particles, increasing the fluidising velocity beyond wmf gives rise to a uniform expansion of the bed. The homogeneous expansion of a gas-solid system is generally described using the Richardson-Zaki equation 13... 

The Richardson Zaki equation (Equation 37) is used in fluidisation to describe the homogeneous expansion. It relates the superficial gas velocity to the fluid bed voidage and particle terminal fall velocity ... 

Combustion occurs over a larger range in the gasifier which is almost homogeneous in temperature at about 1,000°C. Because of the nature of the fluidised bed there is a relatively high level of unconverted carbon present in the ash. The ash and unconverted coal (char) exit the bottom of the vessel. This gasifier is represented by gasifiers of the Winkler type. 

Kilpinen P. and Hupa M, (1991) Homogenous NjO chemistry at fluidised bed combustion conditions, A kinetic modelling study. Combustion and Flame 85 95. 

At velocities above the minimum fluidisation velocity the fluidised bed expands. Its height and void fraction increase. Solid-liquid systems expand continuously with increasing liquid velocity, and the solid particles are homogeneously distributed. In solid-gas systems gas bubbles form inside the fluidised bed, so that a heterogeneous system exists. 

In an homogeneous (bubble free) fluidised bed the velocity with which the particles are just carried at point b is equal to the fluid velocity. Points on the rising branch of the line for flow around a single sphere to the right of point b are attributed to a fluid velocity greater than the particle velocity. They lie in the region of pneumatic transport. 

An observer moving with the fluid would, upon reaching point b, have the impression that the particle was about to start falling. The particle velocity in a homogeneous fluidised bed at point b is the same as the falling velocity ws of a particle in a quiescent fluid. This can be calculated from the balance of the buoyancy FB and resistances forces FR. This is... 

The polymer from the flash tank is fed to a fluidised bed reactor for further polymerisation. No additional new catalyst is needed the polymer continues to grow on the same catalyst particles, resulting in a homogeneous polymer structure. The gas phase reactor operates at 75 - 100 "C and 2 MPa. Fresh ethylene, comonomer and hydrogen are fed into the reactor. In this step, a high molecular weight copolymer is produced. 

The fluidised bed was composed of aluminium, silicon or aluminium/silicon powder. The particle size was less than 200 pm to obtain a homogeneous bed and to improve the conditions of heat and mass transfer. The bed was then fluidised with an increasing flow rate of argon during the heating-up period. 

Pack cementation as well as fluidised bed chemical vapour deposition have been extended to temperatures below 715°C. Homogeneous diffusion aluminide Fe2Al5 coatings of up to 50 pm thick have been obtained by pack cementation. FBCVD has shown a higher success for the Al-Si co-deposition. Further improvement is, though, required for the Si deposition as well as the pack cementation codiffusion at low temperatures. 

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