Designing of the dryer section of nutritional yeast production plant – Industrial sector review – Part 16

Designing of the dryer section of nutritional yeast production plant – Industrial sector review – Part 16

PROCESS DESCRIPTION

In this section, details of the mass and energy balances along with the drying process description are detailed.

Introduction

Yeast broth from the fermentor is delivered to separator which produces a thick suspension of yeast (cream). Moisture in the cream needs to be evaporated to get the dried product (protein supplement powder) with optimum moisture
content. This is done by spraying the cream into a drying vessel through which a stream of hot air is passed. In this way a large interfacial area of the cream is generated resulting in high rate of moisture evaporation.

Due to a fine sub-division of the cream, the dried yeast is produced in finely divided state. Moreover, the temperature of the sprayed cream remains below the saturated wet-bulb temperature of the air resulting in a convenient
way of the yeast production. Note that too much of high temperature may deteriorate the product as the yeast is heat sensitive. The dryer selected for drying the yeast broth is the spray dryer.

The process of evaporation of moisture from the feed to the air in the dryer takes place in four process stages which are;

1)    Atomization of feed

2)    Spray air contact

3)    Drying of spray

4)    Separation of dried products from the air.

The process description and the design of each process stage is explained in this section

Continued in part 17

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Posted by Ahmed Tariq on Feb 29 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