A practical approach to performing Pinch Analysis followed by Heat Exchanger Network retrofit of an oil refinery

Energy efficiency in oil refineries is an effective measure to reduce greenhouse gas emissions and energy use. Research has focused on the application of heat integration in industries; however, little emphasis is given to the practical use of unreliable/unavailable data from the industries and its integration with the energy system. The study used temperature correction factors to produce a balanced heat exchanger network and study the use of excess heat for district heating. It also validated the proposed retrofits by analysing the impact of the retrofit on the area of all heat exchangers in the network. Finally, it evaluates the robustness of the results due to input temperatures and mass flow rates. A Pinch analysis of a section of plant was done before optimising the heat network. The thermodynamic ideal heating and cooling energy targets of the heat network were 74 MW, which exceeded the actual energy use by 20%. The pinch point was 254.7 °C at a global minimum temperature of 30 °C. Retrofits were proposed to reduce this inefficiency and amount of excess heat for district heating was quantified. The retrofits were simulated in PRO/II software to analyse its impact on the entire heat network. The best-case scenario had a net present value of 51 MDKK over 15 years, with avoided emissions equal to 11.4 KTonsCO2 eq./year. Uncertainty analysis, done through Monte Carlo simulation, found that the Energy Targets were quite robust against the defined uncertainties.