Page 156 - Sustainability in the Process Industry Integration and Optimization

Fu r t h e r A p p l i c a t i o n s o f P r o c e s s I n t e g r a t i o n 133

capital supply line up to the maximum allows one to target both the
investment level and the expected annual benefit (Figure 6.9).

6.4.2 Materials Reuse-Recycle and Property Pinch Analysis
The composition of a substance is only one of several chemical and
physical properties that are essential in a chemical process. Other
common properties include acidity and alkalinity (as measured by
pH), density, viscosity, reflectivity, turbidity, color, and solubility.
The process network synthesis associated with these chemical
properties cannot be addressed by conventional mass integration
techniques, so another generic approach has been developed to deal
with this problem (Shelley and El-Halwagi, 2000; El-Halwagi et al.,
2004). For systems that are characterized by one key property,
Kazantzi and El-Halwagi (2005) introduced a Pinch-based graphical
targeting technique that establishes rigorous targets for minimum
usage of fresh materials, maximum recycling, and minimum waste
discharge.
Foo and colleagues (2006) focused on developing an algebraic
technique to solve the problem of identifying rigorous targets for
property-based recycling and reuse of materials. A key element of
these techniques is the concept of material surplus, which generalizes
the analogous concept developed for tasks of synthesizing hydrogen
and water networks (Alves and Towler, 2002; Hallale, 2002). Foo et al.
(2006) developed an algebraic approach called property cascade analysis
(PCA) to identify various performance targets for a maximum
resource recovery (MRR) network. This paper also introduced
network design techniques for the synthesis of an MRR network as

20
Investment [$] 15

10

20 40 60 80
Savings [$]
Separate stage of design
Composite Curve
Capital (investment) Supply Line
1
2
Grid 3
4

F

FIGURE 6.9 Targeting and project management (after Zhelev, 2007).