TABLE OF CONTENTS Figure 1.1(a) shows an outline flowsheet representing a traditional design for the front end of a specialty chemicals process. Six heat transfer "units" (i.e. heaters, coolers and exchangers) are used and the energy requirements are 1,722 kW for heating and 654 kW for cooling. Figure 1.1(b) shows an alternative design which was generated by Linnhoff et al. (1979) using pinch analysis techniques (then newly developed) for energy targeting and network integration. The alternative flowsheet uses only four heat transfer "units" and the utility heating load is reduced by about 40% with cooling no longer required. The design is as safe and as operable as the traditional one. It is simply better.
Results like this made pinch analysis a "hot topic" soon after it was introduced. Benefits were found from improving the integration of processes, often developing simpler, more elegant heat recovery networks, without requiring advanced unit operation technology.
There are two engineering design problems in chemical processes. The first is the problem of unit operation design and the second is the problem of designing total systems. This book addresses the system problem, in particular design of the process flowsheet to minimise energy consumption.
The first key concept of pinch analysis is setting energy targets. "Targets" for energy reduction have been a key part of energy monitoring schemes for many years. Typically, a reduction in plant energy consumption of 10% per year...
