A retrospective on design and process synthesis
Introduction
Since the mid-1960s, we have witnessed a rapidly increasing impact of systems engineering concepts on process engineering design that are largely coincident with the improvements in computing. We examine this impact, one that has very often come from the connecting together of well-understood parts to form a larger system.
The role of process systems engineering (PSE) is complex, ranging from new, powerful design methods, to how we think about the design process itself, to using operation issues in design decision making, to using design simulation methods to aid operations. As noted in an AIChE presentation by Perkins (1998), the entire issue of the AIChE Symposium Series No. 46 from 1962 usurped the title of PSE, and, in the introduction to that issue, we see the concept defined exactly as we are doing here. The term gained prominence in recent times as the name of a conference that took place in Kyoto, Japan, in 1982. No doubt we shall find even earlier references as the concept of unit operations, which apparently first appeared about 1915, leads to worrying about how to connect them together to form a process.
Section snippets
Designing
We start by asking what is the act of designing. Designing is often largely an art form. It is frequently the knowing of previous solutions, combined with guessing and then computing and/or proving experimentally that some new equipment arrangements might work better. This evolutionary approach can lead to some very sophisticated designs. However, with this approach, one can never be sure that much better designs are not possible. One goal of PSE is to provide methods that allow us to invent
Design as a mathematical programming problem
If we know how to enumerate all the alternatives that we are willing to consider for a design and if we can evaluate these alternatives using appropriate quantitative measures, then we can in principle set up our design problem as a mathematical programming problem. In the extreme we can simply enumerate all the alternatives, evaluate them, and select the best design.
There are several issues to worry about with this approach. First, we really need to understand a problem well—it must be
Synthesis—representations for innovation
Process synthesis is very much the fun part of engineering. It is where one invents the structure and operating levels for a new chemical manufacturing process. One of the first publications on synthesis significantly predated the use of the word (Lockhart, 1947). It asked whether one should separate a ternary mixture by first separating the most volatile or by first separating the least volatile component. Rudd and co-workers introduced the term “synthesis” in the late-1960s (Masso & Rudd, 1969
In closing
We have looked at the impact of PSE on the design of chemical processes. The impact became possible with the advent of computing. Desktop computing has attained “giga” rates for both instructions executed per second and bit transfer over our inter- and intranets and giga sizes for fast memory. In June of 2000, IBM announced7 a 12.3 teraflop (1012) computer, over 1000 times faster than the fastest PCs at that time.
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