Spray drying in a pressure vessel

[Stepheno]

Normally, spray drying is carried out at atmospheric pressure.

Is it possible to / are there any examples of spray drying with the chamber vessel (i.e. post atomisation) under pressure (e.g. 10 bar)?

Presumably it would be difficult, but not impossible, to carry out the removal of cold air / introduction of hot air, as well as the removal of final product, under these circumstances.

 

[micalbrch]

I'm not aware of a pressurized spray dryer. All I have seen in ceramics and chemicals are not pressurized. What do you think is the advantage?

 

[Stepheno]

For example, it could be beneficial to have air occluded in the final particles at pressures greater than atmospheric.

 

[micalbrch]

Uuh! O.k. that can be benificial although I cannot imagine any application yet. But that's not the problem at the moment. I have doubts that one can control the process of occluding air in the particles. The pressure inside the vessel alone will not ensure that.

 

[hacksaw]

the drying process loses effectiveness as the pressure increases, vaccuum towers are more cost effective

 

[Stepheno]

micalbrch: It is fairly straightforward to control the occlusion of gases in spray dried particles, many examples are found in pharmaceuticals and food. However the approximate final pressure of the occluded gas will be approximately equal to the pressure of the tower.

hacksaw: I don't understand this—could you provide an explanation or examples? Many thanks.