Inertial granulation

Hence, the extent of non-inertial growth depends logarithmically on binder viscosity and the inverse of agitation velocity (Adetayo et al., 1995). Maximum granule size depends linearly on these variables. Also, the extent of growth has been observed to depend linearly on liquid loading y and,... 

Newton (power) number, which relates the drag force acting on a unit area of the impeller and the inertial stress, represents a measure of power requirement to overcome friction in fluid flow in a sfirred reacfor. In mixer-granulation applications, this number can be calculated from the power consumption of the impeller or estimated from the power consumption of the motor. 

Gas velocity Increases attrition and elutriation rates (major effect) Decreases coalescence for inertial growth Has no effect on coalescence for noninertial growth, unless altering bed moisture through drying Increases granule consolidation and density... 

Binder viscosity Increases coalescence for inertial growth Has no effect on coalescence for noninertial growth Decreases granule density... 

The exponents a and in Equation (13.19) are dependent on granule deform-ability and on the granule volumes u and v. In the case of small feed particles in the non-inertial regime, P reduces to the size-independent rate constant Po and the coalescence rate is independent of granule size. Under these conditions the mean granule size increases exponentially with time. Coalescence stops ( = 0) when the critical Stokes number is reached. 

Explain the non-inertial, inertial, and coating regimes of granule granule growth. What happens to the maximum granule size as (a) the approach velocity increases, (b) the viscosity increases ... 

Inertial growth USt,, k. Sf) Some collisions cause coalescence while the others lead to rebound. There will be steady granule growth by coalescence. The extent and the rate of growth will be sensitive to process parameters which will determine the proportion of collisions that lead to coalescence. Varying process parameters and formulation properties can push the system into either the noninertial or the coating regimes. 

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