[popay73]

Hi,

Regarding fluid bed granulation I have some dilema with processw parameters I hope You can help me with.
I work in pharmaceutical company and we use batch granulation; air comes from bottom and we spray product from top.

I know for granule growth that spray rate, automatization pressure is important.
Also, Inlet air temperature and flow have great impact on granule growth.
Higher spray rate and lower inlet air T makes larger granules and vice versa.
I understand there is an equilibrium betweend evaporating and wetting granules...meaning if we increase inlet air T more spraying liquid will evaporate and there won't be much of a contact with granules, making them small.
Also, if inlet air T is decreased, it would make them too heavy and fluid bed could collapse...
The same is with moisture content, if too high fluid bed could colapse, if too low no granulation will take place...

What I really don't understand is outlet air temperature. If it goes too high granulation is not good, but why ?
Does it go high becouse there is no enough spraying liquid, meaning there is no cooling and T increases ?

After spraying there is drying process. Sometimes drying end point is defined by product temperature and sometimes by outlet air T...I don't understand what tells one and what another T ?
I guess they define product T to be close to ambient T to avoid any condensation issues due to T difference.
I don't have an idea about outlet air T ?

Regards !