Page 165 - Sustainability in the Process Industry Integration and Optimization

142 Cha p te r S i x

2
(a) Cumulative Area [km ] 2 (b) Cumulative Area [km ]

Zone 5 H A
B
Zone 1
C
Zone 4
G
F Zone 2
Zone 3 E
D
Zone 3
Zone 2 D
E
Zone 4 F G
Zone 1
C
B Zone 5
A H
Cumulative energy balance [PJ/y] Cumulative energy balance [PJ/y]
FIGURE 6.17 Regional Resources Management Composite Curve.

6.5 Heat-Integrated Power Systems: Decarbonization
and Low-Temperature Energy

6.5.1 Decarbonization

Conventional utility systems focus on how to produce and utilize the
steam in a steam distribution network (Varbanov, Doyle, and Smith,
2004). Unlike conventional steam-based utility systems, however,
power-dominated energy systems exhibit different characteristics
because the provision of shaft (driver) power, rather than steam, is of
paramount importance. For such power systems (e.g., in natural gas
liquefaction), a key issue is selection of the most appropriate drivers
to satisfy mechanical shaft demands. The decision factors in driver
selection include the optimal number, type, and size of the drivers,
helper motors or generators, and power plants—subject to a set of
mechanical and electricity demands and relevant economic scenarios.
Zheng, Kim, and Smith (2008a) developed a holistic approach to
account for design interactions in power systems, given that driver
selection entails unique implications for the overall design; these
factors include overall cost, fuel consumption, performance, plant
availability, carbon emissions, and so forth.
Synthesis complexity increases significantly when steam systems
are considered together with power-dominated systems. This case
arises when a process requires a large amount of heat (steam) or
when a steam turbine is preferable (as a direct driver) to a gas turbine
or electric motor. In such cases, additional information is required
about the on-site power supply and the way drivers interact with
generating facilities. Implementation of a CO (carbon dioxide)
2
capture process in the plant requires extra compression duty for the