AstraZeneca uses Amzi! in Expert System
for Selecting Chemical Processing Agitators
Critical to the successful manufacture of fine chemicals is the process
of mixing and stirring. However, selecting agitation systems for stirred
vessels is both complex and difficult. There is a wide range of both available
systems (different impellers, types of baffles etc) and of duty performed
(e.g. blending, solids suspension or heating). Therefore, selecting an
optimal, or even feasible, system for a given duty demands considerable
experience. Adding to the complexity, a particular duty may involve satisfying
several different design objectives simultaneously.
With this in mind, AstraZeneca PLC, one of the world's leading pharmaceutical
and agrochemical companies, created an expert system to aid in the selection
of the correct agitation system.
AstraZeneca selected Amzi! Prolog + Logic Server over a commercial expert
system because it offers both the advantages of custom design with Prolog
and seamless integration with Delphi. The drawback of a commercial shell
is that its problem resolution strategy would not accurately map to the
way that engineers pick agitators for stirred vessels.
The strategy used to select an agitator is: collect data for objectives
of agitation, assess relative importance of each, reject unsuitable systems,
rank allowable systems, pick best. So it is a two-phase weighting and
analysis process, which is not a way of reaching solutions with a commercial
Prolog alone is great for knowledge representation and reasoning. However,
it does not provide good tools for implementing the easy-to-use GUI that
would interact with the engineer selecting the agitator. Additionally,
Prolog does not provide good support for the number-crunching aspects
of the problem, the results of which are used in deciding which agitator
Taking advantage of Amzi! Prolog + Logic Server's seamless integration
of Prolog with Delphi, AstraZeneca created both a classic Windows look
and feel, as well as leveraged the speed benefits Delphi offers for numerical
Prolog calls Delphi to interact with the user via the GUI when it needed
information, and to perform number-crunching as needed. The end-result
is an intelligent GUI that is driven by a reasoning engine.
The knowledge is represented using lists of ASCII strings, which can
easily be modified with a text editor. Callback functions are used to
build a user-friendly front end with standard Windows appearance.
AstraZeneca cites additional benefits of the system. Users inexperienced
in agitator system design can specify systems for most duties. Because
the expert system prompts the user for relevant data, they are guided
in obtaining the appropriate data for design at an early stage.
Zeneca Process Studies Group
Huddersfield, HD2 1FF
Phone: +44 1484 48 6074
Fax: +44 1484 48 6057:
Contact: Dr. Frans Muller
or Dr. Alan Hall
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