2 replies to this topic

[DezsoSajer]

Dear All,

I am working for a company who bought a second-hand spray dryer with an integral drying and an external cooling fluid bed.

We used to have a consultant who advised us that if we remove the integral fluid bed, and use half of the external fluid bed as second stage drying, the throughput of the dryer should increase.

I failed to find any logic for that, maybe someone here could help me with that.

After all, what are the advantages and disadvantages of using an integral fluid bed in a spray dryer?

Thanks in advance

[sgkim]

Hi,

 

Your present dryer seems to have two different functional system - spray dryer and cooling bed.  If the cooling bed is utilized as the additional dryer, the drying capacity will surely increased as your consultant suggests.  

 

But the following issues still remain:

-The moisture content increase of the powder from the spray dryer may give troubles due to the wet cake build-up, which will often clog the bottom discharge nozzle.

-Fluidized bed dryer may not be operated properly if the wet cake tends to coagulate,  which prohibits homogeneous fludization.

-If the wet powder (of cake) coagulate easily,  the fludized bed dryer might be re placed with "agitated fludized bed dryer" or "agitated flash dryer"  

-Final product cooler may be added on the second stage dryer outlet, if only a 'cool powder" is acceptable on the downstream.

 

Gooluck, 

 

~Stefano Kim

[ganesh_bodakhe]

Stefano has given all right answers. But most important are the Slurry Characteristics, rheology and desired product characteristics you wanted to produce. The most important is temperatures you are going to use in 3 stages. If the product is having low glass transition temperature, or thermoplastic in nature, can degrade at higher temperature then you need to plan out proper drying.  Product throughput will increase due to higher suction air flow as one of the supply fan is going to be eliminated. but at the same time you may be missing with yield. In case of any more help you can write back to me with product details then will be able to help.