Drying process in industrial sector – Part 1

Drying process in industrial sector – Part 1

Drying is the final unit operation in the manufacture of the protein supplement. The performance of this stage determines the component make up of the final product which is to be sold in the market.

As throughout the rest of the process the first decision is whether or not to run the operation as a batch or continuous process.

A wide range dryer designs are available that can be used to dry the product cream out of the separators. Batch dryers (e.g. tray and tunnel dryers) are normally used where the relatively small scale production is required, that is the duty of the dryer
is not high. It uses a direct heating method (high thermal efficiency), but it cannot produce finely divided product and is therefore do not meet our product requirements (Coulson and Richardson, 1991)

The amount of water that is needed to be evaporated from the incoming stream is calculated as 1555 kg/hr. This is such as to produce the required amount of powdered yeast with optimum moisture content of 8%. This evaporation rate is too high for any batch
dryers, and therefore a continuous dryer is to be used in this process.

The Choice of the dryer to be used in the design depends on many factors, of which the most influencing are:

• The type of feed (liquids, liquid suspensions, high solid density cakes)

• The moisture content to be removed from the feed, the load.

• The size and shape of the end product

• Heat sensitivity

• Loss in activity,  effect on viability and nutritional value

Out of the many continuous dryers available, the drum dryer and spray drier is of most interest as these are specially designed in drying of liquids or liquid suspensions. Note that our feed to the dryer only contains 18% dry solids with the remainder being
of the content being moisture.

Some other continuous driers of note include:

• The rotary dryer. This is best used for large scale drying of materials. It is mainly not considered for heat sensitive and product shape quality requirements. Both direct heating and indirect heating can be used in this dryer.

• The pneumatic or continuous fluid bed dryer. If complete dispersion of the product in a heated gas stream can be achieved and the material to be dried is too fine, than this type of dryer is preferred. Theses dryers are quite similar to the spray drier
  in their operating principles.

Short URL: https://www.newspakistan.pk/?p=10734

Posted by Ahmed Tariq on Jan 27 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