Customer Stories

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 shell.

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 ranks highest.

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 calculations.

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 Works
Leeds Road,
Huddersfield, HD2 1FF
U.K.
Phone: +44 1484 48 6074
Fax: +44 1484 48 6057:
Contact: Dr. Frans Muller or Dr. Alan Hall