Modelling and Optimisation of Heat Recovery Systems (HRS) using the ThermWatt Computational Tool

November 20, 2024

This work subsists on the modelling of a Heat Recovery System (HRS) within a petrochemical plant and the further economic and environmental viability assessment of the associated project. The conceptualised system includes four combustion-based processes and a condensing steam turbine combined heat and power (ST-CHP) generation system, in addition to a set of waste heat recovery technologies to reduce the overall energy use of the plant. The developed system-based approach extends a previous methodology, initially focused on reducing energy consumption in production processes, to encompass energy supply systems (in which CHP is included) as well. A set of simulation and optimisation models were developed for the proposed system (both using approximately the same set of variables and governing equations) using the Modelica language and the Python language-based GEKKO package respectively, implementing the capabilities of the ThermWatt computational tool designed for energy recovery and water systems modelling. Two improvement scenarios were conceptualised for the proposed HRS, consisting in preheating either the combustion air stream or the water at the inlet of the ST-CHP boiler. The second scenario demonstrated the highest potential related to the reduction of energy-related operational costs, thus serving as the basis for the development of the optimisation model, built using the nonlinear programming methodology. A payback period of about 2 years and 3 months and a 5.14 kt CO2,eq/year reduction were estimated for the final system, which are significantly reasonable in comparison to benchmark values.

Authors in the community:

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  D

  Daniel Rodrigues Sousa

  ist196588

Supervisors of this institution:

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  M

  Maria Cristina De Carvalho Silva Fernandes

  ist12192

chemical-engineering - Chemical engineering

eng - English

Instituto Superior Técnico