Page 36 - Sustainability in the process industry

P r o c e s s I n t e g r a t i o n 13

(Linnhoff et al., 1982; Linnhoff et al., 1994; Shenoy, 1995; Smith, 2005;
El-Halwagi, 2006; Kemp 2007; Klemeš, Smith, and Kim, 2008).
One of the first works in this field was Hohmann’s (1971) PhD
thesis, which introduced a systematic thermodynamics-based
reasoning for evaluating the minimum energy requirements for a
given HEN synthesis problem. In the late 1970s this work was
continued by Linnhoff and Flower, who used Hohmann’s foundation
to develop the basis of Pinch Technology—now considered the
cornerstone of HI. As is often the case with a pioneering innovation,
this work was difficult to publish. Yet the authors’ strong commitment
eventually led to the publication of their ideas in Linnhoff and
Flower (1978), which has since become the most cited paper in the
history of chemical engineering. Similar work (Umeda et al., 1978;
Umeda, Harada, and Shiroko, 1979) was independently published in
Japan, but it was Linnhoff (supported by teams from UMIST and
later Linnhoff March Ltd.) who pushed the new concept through
academia and industry. The publication of the first “red” book by
Linnhoff et al. (1982) played a key role in the dissemination of HI
methodology. This user’s guide to Pinch Analysis detailed the most
common process network design problems, including HEN synthesis,
heat recovery targeting, and selecting multiple utilities.
These methodologies were developed and pioneered by the
Department of Process Integration, UMIST (now the Centre for
Process Integration, CEAS, the University of Manchester) in the late
1980s and 1990s (Linnhoff et al., 1982; Linnhoff and Vredeveld, 1984;
Linnhoff et al., 1994; Klemeš et al., 1997; Smith et al., 2000; Smith,
2005). A second edition of Linnhoff’s user’s guide was published by
Kemp (2007). Applications of HI in the food industry were presented
in Klemeš and Perry (2007a) and in Klemeš, Smith, and Kim (2008).
Tan and Foo (2007) successfully applied the Pinch Analysis approach
to carbon-constrained planning for the energy sector, and Foo, Tan,
and Ng (2008) applied the cascade analysis technique to carbon-
footprint-constrained energy planning.
Another important part in process design and optimization is
the synthesis phase of process flowsheets. From the earliest stages of
PI there have been attempts to combine it with optimization (see, e.g.,
Giammatei, 1994). Such combining is usually performed after the
targeting phase mentioned previously. Ideally, the structure of the
entire process—and the configurations of the operating units within
it—should be simultaneously designed and optimized, because the
performance of each unit influences the others. The main source of
complexity in this synthesis is the problem’s dual nature of being
both continuous and discrete. There are several known methods for
performing the task, including heuristic, evolutionary, and
superstructure-based approaches. Two major classes of methods for
process synthesis are heuristic and algorithmic (or Mathematical