Page 120 - Sustainability in the Process Industry Integration and Optimization

P r o c e s s I n t e g r a t i o n f o r I m p r ov i n g E n e r g y E f f i c i e n c y 97

Emissions
Emissions
Power
Fuel 1
Fuel 2 Condensing HP Steam
Emissions MP Steam
LP Steam

Fuel 3 Plant A Plant B Plant C
Cooling

FIGURE 4.65 Schematic of an industrial Total Site.

4.6.1 Total Site Data Extraction

The heating and cooling requirements of the individual processes
are represented by their respective GCCs (see Section 4.3.5). The
GCC represents the process-utility interface for a single process.
These individual GCCs can be used to identify the potential heat
recovery via steam mains. When a site houses several production
processes, the GCC of each process may indicate certain steam levels
that are suitable for the given process. This suggests that trade-offs
need to be made among energy demands of the various processes
on a Total Site, since each process usually needs utility heating or
cooling at levels different from the other processes.

4.6.2 Total Site Profiles
It is possible to set utility targets for sites involving several processes
(Dhole and Linnhoff, 1993b; Linnhoff and Dhole, 1993; see also
extensions by Klemeš et al., 1997). The procedure is based on
thermal profiles for the entire site that are called, naturally enough,
Total Site Profiles (TSPs). These profiles are constructed from the
GCCs of the individual processes on the site. The first step (see
Figure 4.66) is to extract the net heating and cooling demands. Two
options are possible: restricting the Heat Integration to each process
(so that heat recovery pockets are not considered for Total Site
analysis) or to allow extended integration across processes by
including the GCC segments forming the pockets. When the scope
of site integration is extended, however, some design possibilities