Analysis of bulk solids
First and foremost, an analysis of the bulk goods to be conveyed is required in order to choose the appropriate procedures/systems and components
Geldart divides the bulk cargos according to their fluidization behaviour and air retention into the groups A, B, C, D, providing a rough classification of the conveying characteristics
A fine-grained powder with low density, easily fluidised with
good air retention
B medium granulation with medium density, some
fluidisation properties with poor air retention
C fine powders with higher density, cohesive, poor
fluidisation properties with poor air retention
D larger granulation with higher density, no fluidisation properties, no air
retention
Jenike describes the flowability of the bulk goods using the yield function FFC, providing a rough classification of discharge behaviour from tanks. His classification is:
Freeflow 10 ≤ FFC < ∞
Flow 4 ≤ FFC < 10
Cohesive 2 ≤ FFC < 4
Very cohesive 1 ≤ FFC < 2
Non flow, hardening FFC < 1
The conveying characteristics and the discharge behaviour from tanks are both relevant for the planning of pneumatical plug conveying, and therefore must be included in the evaluation.
Additionally the nature of the task and the specific requirements such as the maintenance of the product characteristics, granulation, volume, bulk weight, no contamination etc., have to be considered.
