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Title: Simulation-based process design and integration for retrofit
Author: Hernandez Enriquez, Aurora
ISNI:       0000 0004 2696 3307
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2010
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This research proposes a novel Retrofit Design Approach based on process simulation and the Response Surface Methodology (RSM).Retrofit Design Approach comprises: 1) a diagnosis stage in which the variables are screened and promising variables to improve system performance are identified through a sensitivity analysis, 2) an evaluation stage in which RSM is applied to assess the impact of those promising variables and the most important factors are determined by building a reduced model from the process response behaviour, and 3) an optimisation stage to identify optimal conditions and performance of the system, subject to objective function and model constraints. All these stages are simulation-supported. The main advantages of the proposed Retrofit Design Approach using RSM are that the design method is able to handle a large industrial-scale design problem within a reasonable computational effort, to obtain valuable conceptual insights of design interactions and economic trade-off existed in the system, as well as to systematically identify cost-effective solutions by optimizing the reduced model based on the most important factors. This simplifies the pathway to achieve pseudo-optimal solutions, and simultaneously to understand techno-economic and system-wide impacts of key design variables and parameters. In order to demonstrate the applicability and robustness of the proposed design method, the proposed Retrofit Design Approach has been applied to two case studies which are based on existing gas processing processes. Steady-state process simulation using Aspen Plus TM® has been carried out and the simulation results agree well with the plant data. Reduced models for both cases studies have been obtained to represent the techno-economic behaviour of plants. Both the continuous and discrete design options are considered in the retrofitting of the plant, and the results showed that the Retrofit Design Approach is effective to provide reliable, cost-effective retrofit solutions which yield to improvements in the studied processes, not only economically (i.e. cost and product recovery), but also environmentally linked (i.e. CO₂ emissions and energy efficiency). The main retrofitting solutions identified are, for the first case, column pressure change, pump-around arrangement and additional turbo-expansion capacity, while for the second case, columns pressure change, trays efficiency, HEN retrofit arrangements (re-piping) and onsite utility generation schemes are considered. These promising sets of retrofit design options were further investigated to reflect implications of capital investment for the retrofit scenarios, and this portfolio of opportunities can be very useful for supporting decision-making procedure in practice. It is important to note that in some cases a cost-effective retrofit does not always require structural modifications. In conclusion, the proposed Retrofit Design Approach has been found to be a reliable approach to address the retrofit problem in the context of industrial applications.
Supervisor: Kim, Jin-Kuk Sponsor: Consejo Nacional de Ciencia y Tecnología de Mexico (CONACYT)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Retrofit design; Process integration; Computer simulation; Response Surface Methodology; Cleaner production; Environmental emissions.