Optimizing the Drug Pills Throughput in Ciba’s Droppo Tower
Overview: The DROPPO tower developed by CIBA Switzerland (now BASF) is meant to produce a high throughput of drug pills for medicinal purposes. The process involves injecting a large amount of pills in form of 5mm diameter liquid droplets in a 20m height round tower from a series of rings with a multi-hole injection systems. The pills fall by gravity and are cooled down by a countercurrent air flow injected from below. The challenge is that the droplets should be cooled down at a sufficient position from the inflow of air. The flow is highly turbulent and may cause particle dispersion leading eventually to droplet coalescence if the critical cooling height is exceeded.
The challenge: The challenge posed to the engineers is how to optimize the overall production system in order to define the best conditions achieving the highest throughput of pills, while minimizing cooling costs and losses (uncooled droplets are lost).
TransAT Solution: With the advanced turbulence modelling conjugated to heat transfer and Lagrangian particle tracking capabilities, with TransAT we could test several configurations for several airflow conditions, involving 2, 3 and 4 rings placed in different positions, with variable dimensions of the injection systems, while varying the number of injection holes and thus the mass loading. With the strict constraints of minimizing droplets entrainment and calescence, with a clear target of 5m maximum distance of cooling from the cooling inlet, we could define exactly the best conditions for an optimal production system, attaining a total pills throughput of 900 kg/hr, which 30% better than the existing established design.
InfoExpert: Contact our expert
Dr Chidu Narayanan
Tel. + 41-44-445-4071