HEAT EXCHANGER NETWORKS RETROFITTED WITH SIMULTANEOUS PRESSURE RECOVERY

HEAT EXCHANGER NETWORKS RETROFITTED WITH SIMULTANEOUS PRESSURE RECOVERY

ONISHI, V. C.; RAVAGNANI, M. A. S. S.; CABALLERO, J. A.

Artigo:

This paper introduces a new optimization model for the retrofit of heat exchanger networks (HENs), wherein the pressure recovery of process streams is used to enhance the heat integration. Especially important in cryogenic processes, the HEN retrofit with optimal integration between heat and work is mainly aimed at reducing the usage of the extremely expensive cooling services. In this approach, the conventional problem of HENs retrofit is extended to include streams subjected to a specific pressure manipulation route. Thus, the adjustment of pressure levels of process streams is performed simultaneously with the HEN synthesis, such that the streams pressure and temperature are optimization variables. The mathematical model based on a mixed-integer nonlinear programming (MINLP) formulation allows for the increment of the existing heat exchange area, and the use of new equipment for both heat exchange and pressure manipulation. Moreover, the proposed superstructure considers the coupling of turbine and compressor with a helper motor, in order to minimize the total annualized cost composed by additional capital and operational expenses. A case study is conducted to verify the accuracy of the proposed approach. The results indicate that the pressure recovery is essential for reducing the energy consumption in a sub-ambient process and, consequently, for decreasing the total cost of the HEN retrofitted.

This paper introduces a new optimization model for the retrofit of heat exchanger networks (HENs), wherein the pressure recovery of process streams is used to enhance the heat integration. Especially important in cryogenic processes, the HEN retrofit with optimal integration between heat and work is mainly aimed at reducing the usage of the extremely expensive cooling services. In this approach, the conventional problem of HENs retrofit is extended to include streams subjected to a specific pressure manipulation route. Thus, the adjustment of pressure levels of process streams is performed simultaneously with the HEN synthesis, such that the streams pressure and temperature are optimization variables. The mathematical model based on a mixed-integer nonlinear programming (MINLP) formulation allows for the increment of the existing heat exchange area, and the use of new equipment for both heat exchange and pressure manipulation. Moreover, the proposed superstructure considers the coupling of turbine and compressor with a helper motor, in order to minimize the total annualized cost composed by additional capital and operational expenses. A case study is conducted to verify the accuracy of the proposed approach. The results indicate that the pressure recovery is essential for reducing the energy consumption in a sub-ambient process and, consequently, for decreasing the total cost of the HEN retrofitted.

Palavras-chave:

DOI: 10.5151/chemeng-cobeq2014-0245-26354-183068

Referências bibliográficas

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Como citar:

ONISHI, V. C.; RAVAGNANI, M. A. S. S.; CABALLERO, J. A.; "HEAT EXCHANGER NETWORKS RETROFITTED WITH SIMULTANEOUS PRESSURE RECOVERY", p-11350-11357. In: Anais do XX Congresso Brasileiro de Engenharia Química - COBEQ 2014 [= Blucher Chemical Engineering Proceedings, v.1, n.2]. São Paulo: Blucher, 2015.
ISSN 23591757, DOI 10.5151/chemeng-cobeq2014-0245-26354-183068