Authors:
Kitipat Siemanond
and
Supachai Kosol
Affiliation:
Chulalongkorn University, Thailand
Keyword(s):
Heat Exchanger Network (HEN), Pinch analysis, Mixed integer linear programming, Stage model, Retrofit.
Related
Ontology
Subjects/Areas/Topics:
Application Domains
;
Chemical and Petroleum Engineering
;
Formal Methods
;
Industrial Processes
;
Optimization Issues
;
Simulation and Modeling
Abstract:
This study explores the retrofitting of the crude preheat train of a crude distillation unit (CDU) processing two types of crude--light and heavy--for a period of 200 and 150 days per year, respectively, with the aim of finding the optimal design that would yield the highest net present value (NPV). A mathematical programming model using GAMS software of heat exchanger network (HEN) called stage model (Zamora and Grossmann, 1996) is applied to carry out the retrofit. The base case CDU is simulated by PRO II software. Using pinch analysis, the composite curves show the retrofit potential of base cases with light and heavy crude. The 10-stage model generates six retrofit designs--Designs 1, 2, 3, 4, 5, and 6--of which Designs 1, 2, and 3 are suitable for light crude and Designs 4, 5, and 6 are suitable for heavy crude. Using a graphical technique of searching for optimization with maximized NPVs of all designs, it is shown that Design 2 is the optimal retrofit design processing both ty
pes of crude, yielding the highest NPV of $11,529,511 for a 5-year lifetime and resulting in furnace duty saving of 32%.
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