Page 138 - Analysis, Synthesis and Design of Chemical Processes, Third Edition

There are clear parallels between these three product design strategies. It is observed that the first step in
each strategy is the identification of customer needs. The ideas and selection steps of Cussler and

Moggridge [1] are identical to the generate product concepts and select product concepts steps of Ulrich
and Eppinger [4], respectively. The strategies of Dym and Little [3] and Ulrich and Eppinger [4] all
include several design and product-testing steps. Although these are not explicitly included in the strategy
of Cussler and Moggridge [1], they will have to be part of any product design strategy. For example, no
one would begin to manufacture a product without first making a small amount in the lab and testing it.

It is instructive to observe the parallel between the strategy of Dym and Little [3] and the increasing
levels of capital cost estimates in process design illustrated in Table 7.1. Moving from a feasibility
estimate through a detailed estimate parallels moving from a conceptual design to a detailed design.
Similarly, the evolution of a detailed P&ID from a PFD also parallels the evolution from a conceptual
design to a detailed design.

In the following sections, the strategy of Cussler and Moggridge [1] is illustrated using several examples.

4.2 Needs

A new chemical product is sought in response to a need. The need might be those of individual customers,
those of groups, or those of society. Consider the case of Freon refrigerants. In the 1980s, Freons were
identified as having high ozone-depleting potential because of their chlorine content. Therefore, a need for
an environmentally friendly chemical with the appropriate properties of a refrigerant was established.
This led to the development of fluorocarbon refrigerants (e.g., R-134a) and methods for their synthesis.
However, this did not solve the problem entirely. It was then determined that the new refrigerants were
incompatible with typical compressor lubricants. This created the need for a new lubricant that was

compatible with the new refrigerant. Subsequently, this new lubricant was developed, and the new
refrigerant began to be phased in as Freons were phased out.

Chemical companies devoted to product design (e.g., food products, personal care) deal with customers

all the time. Customers are interviewed, often in focus groups, and the results of these interviews must be
interpreted and made into product specifications. This is an inexact “science.” Care must be taken to
define the correct need.

As an example, consider the needs of vessels used for space travel (e.g., the space shuttle) as they reenter
Earth’s atmosphere [5]. The customer, NASA, initially sought the development of a material that would
withstand the temperatures of reentry. Such a material was never developed. Once the problem was
redefined, a more appropriate need was defined. The real need was not to have a material capable of