A study on the Use of Proportional Integral control in the Production of Non Fat Dairy Milk Powder

Abstract

This study looks into the development of a milk drying system which uses proportional integral (PI) control to achieve its aim of taking in skim milk at about 9% total solids and outputting Non Fat Dry Milk powder at about 454 kilograms per hour, with a moisture content of about 3.5%. This was achieved by breaking the system into two main sub systems: an Evaporating and Drying system. Evaporating and drying in themselves, are not new food processing concepts. That being said, the stipulations on moisture content post processing of milk are not usually as strict as 3.5%. Where this study excelled, was in the way it combined these two concepts along with control system automation concepts to meet this stringent moisture content stipulation. The evaporating system employs PI control in order to maintain vacuum as well as the total solids percent at its output. The Drying system employs PI control in maintaining a steady feed rate to the main drying chamber, atomizing the feed to the chamber, maintaining drying as well as cooling temperatures for the final product. The study was successful in using PI control to produce non fat dairy milk (NFDM) powder that was properly atomized and outputted at about 456 kilograms per hour with a total solids percentage of about 96.5% consecutively for about 20 hours.