The Generation and Use of Partial Solutions in Process Synthesis

The use of automated tools can be of great benefit to an engineer involved in a large, complex task such as the design of a chemical plant. Such tools, however, must provide the engineer with more than just a solution to the problem. It is vital that the engineer be given an insight into the reasons for the choice of a given solution. This is particularly important in optimization of complex problems. In these cases, the advantages of the solution (other than a better value of the objective function) are often not immediately obvious and the user is asked to take the results on faith. A process synthesis procedure which provides some indication of why a particular design alternative was chosen can be invaluable, especially during the early stages of design when many decisions are still to be made. This paper describes a novel implicit enumeration method, using dynamic programming, which enables and encourages an engineer to easily explore the solution space for new problems. When completely feasible solutions are not available, the synthesis tool provides information in the form of partial solutions which can lead to a better understanding of or a different perspective on the problem. Using partial solutions, the method can itself generate better solutions, dynamically increasing the search space for solutions that include complex recycle structures.