Page 276 - Sustainability in the Process Industry Integration and Optimization
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CHAPTER 11
Industrial Applications
and Case Studies
his chapter provides an overview of selected implementations
of the Process Integration methodology for various industrial
Tcase studies. The presentation is somewhat condensed because
of space limitations; more information is available in the works
cited.
11.1 Energy Recovery from an FCC Unit
In this case study, the Heat Exchanger Network (HEN) of a Fluid
Catalytic Cracking (FCC) unit process consisted of a main column
and a gas concentration section (Al Riyami, Klemeš, and Perry, 2001).
The stream data was made up of 23 hot streams and 11 cold streams.
The associated cost and economic data required for the analysis were
specified by the refinery owners. Incremental area efficiency was
used for the targeting stage of the retrofit design. This was carried
out using the Network Pinch method (Asante, 1996; Asante and Zhu,
1997), which consists of a diagnosis stage and an optimization stage.
In the diagnosis stage, a few promising retrofit steps were generated
using the UMIST (now the University of Manchester) software
package SPRINT (2009). This software was also used to optimize the
initial design by trading off capital cost against energy savings. The
design options were then compared and evaluated, followed by
the final retrofit design proposed for final inspection.
The existing ΔT of the process was identified as 24°C, and the
min
hot utility consumption of the process was 46.055 MW; the area
efficiency of the existing design was 0.805. The potential for energy
saving was then derived from the resultant Composite Curves, which
are shown in Figure 11.1. As seen in the figure, the Composite Curves
are relatively wide apart except in the area around the Pinch.
The capital cost was estimated under the assumption that the
retrofit distribution of area would be the same as that for the
existing network. The resulting optimum minimum temperature
approach was found to be about 11.5°C for incremental α and about
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