Sizing of a spray dryer – Industrial sector article

Sizing of a spray dryer – Industrial sector article

The sizing of spray dryer on a purely thermal basis is a quite simple since the evaporation is entirely a function of the change in temperature across the dryer. The design of an efficient spray dryer requires considerable expertise along with large scale
test facilities, particularly where particle size and bulk density requirements in the dried product are critical (Sinnott, 2007).

For products that that are dried in on co-current flow driers with rotary air flow, the following recommendations are made (Masters, 1979), (APV drying Handbook, 2000)

Where,

D_ch(min)= Minimum Drying Chamber diameter

E_max = Maximum Evaporative Capacity (note that the required duty of the spray dryer in the process is near 1500 kg/hr as well)

The desired residence of the process is in between 20 to 40 seconds. This time is sufficient for completion of desired moisture removal with minimum increase in the temperature of the product. Drying chamber with Volume of approx. 125m³ is sufficient
enough to provide the residence time of a 20–40 seconds. The Volume of the drying air to be used is 18190 m³/hr (5.05 m³/s) giving nearest stand chamber size of 5.0 m diameter x 3.5 cyl.ht (125m³) (Guidelines based on APV
dryer Handbook,2000 and Masters, 1979).

This residence hence is in the permissible range, and hence it is acceptable. Conical base chamber design is selected as it is most widely used in the spray drying and it leads to better removal of product from the bottom of the chamber.

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Posted by Ahmed Tariq on Mar 1 2012. Filed under Sci-Tech. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry