From laboratory to production scale: Krettek’s easy way
The situation in the early project phases of planning a process plant often presents itself as follows:
- Only small quantities of product are available.
- There is no experience in separating similar products.
- Pilot tests with different centrifuges are cost-intensive.
An initial assessment of the possible separation process is possible in our newly designed cross-check pilot plant with only a small amount of testing. For this purpose, kinetic parameters are determined and the residual moisture achieved is classified in the equilibrium diagram (bond diagram).
Initial tests are carried out in a filter cup centrifuge. Cups equipped with filter cloths are filled with suspension (possibly pre-thickened), suspended in a cup rotor and then centrifuged. In these experiments, g-values, dewatering times and cake heights can be varied.
Fig.1: Filter cup
For these initial tests, Krettek generally requires a small amount of suspension in the range of 3 – 10 liters (depending on the solids concentration).
After a cup centrifugation test, the filter cake is subjected to a flow test with mother liquor or washing liquid to determine the relevant cake resistance according to the Darcy equation.
The residual moisture of the filter cake of another sample is determined by drying in a vacuum drying oven to determine its position in the equilibrium diagram.
The equilibrium diagram is based on the Bond diagram:
Fig 2.: Equilibrium diagram S = f(Bo1) [acc. to Stahl].
For this initial assessment of the separation process, we need some material data from you that is essential for the separation. These are:
- True density of the solid
- Densities and dynamic viscosity of the mother liquor / washing liquid
- Solids concentration
- Surface tension and the contact angle of the washing liquid / mother liquor (necessary for the classification in the equilibrium diagram)
- Particle size distribution
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