Batch Process Control
Process Automation Handbook, chapter 37, Springer, London, (2007)DOI: 10.1007/978-1-84628-282-9_37
Abstract
When raw materials are processed in discrete quantities, the processes are said to be batch or semi-batch. These processes are normally carried out in the liquid phase although solids, usually in the form of a powder,may be fed into the mixture or gases bubbled through it. Batch operations are ones in which all the reagents are charged prior to processing whereas in semi-batch operations the bulk of the reagents are pre-charged but one or more reagents are subsequently trickle fed. Processes may be as simple as a mixing operation or involve complex multi-stage reactions. Such processes are used extensively in the manufacture of bio-chemicals, fine chemicals, pharmaceuticals, and so on.Typically, throughput is of a low volume and high value relative to the continuous processes associated with bulk and commodities chemicals manufacture. Batch process control is concerned with the automatic control of batch processes. Control may consist of a few simple sequences or involve complex recipe handling and batch scheduling. It is invariably carried out by some formof digital control system. This chapter is based upon the IEC 61512 standard for batch process control. Itwas developed by the ISA and is generally referred to as S88. Part 1 of the standard focuses on the models and terminology used. Part 2 focuses on the underlying data structures.Thereare five key models within Part 1: physical, process, procedural, recipe and activity.These establish a framework for the specification of requirements for the control of batch processes and for the subsequent design and development of application software.