Control

Abstract

Controlling batch processes is part of everyday life. Making a pot of tea or coffee for breakfast, a bowl of soup for lunch or a toasted snack for supper are all examples of batch processes. They involve making a limited quantity of a product according to a recipe. This recipe specifies:

• The product to be made and the ingredients required.

• The equipment needed.

• Operations such as mixing and heating.

To make an acceptable (edible) product, these operations have to be carried out in the order, at the temperature and for the time set down in the recipe. They also involve a combination of automatic control (e.g. boiling water in an automatic kettle) and manual actions (e.g. adding tea to the teapot).