Exergetic Pinch Evaluation of a Steam Power Plant Heat Exchanger Network
In this paper, a steam power plant’s heat exchanger network (HEN) is analyzed, using the pinch, exergy, and combined pinch and exergy methodologies, in order to evaluate its performance under design and operational conditions. The pinch analysis show that, under current operational conditions, the minimum hot utility requirement was 539,491kW at a temperature of 549°C, which is 30,618kW (6.02%) more than the design minimum hot utility requirement (508873.7kW), and the optimum minimum temperature difference between hot and cold streams ( ΔT min ) in the HEN is 12°C. Results from standard exergy analysis showed that heaters 5, 2 and deaerator performance improved while the other components experienced decrease in exergetic efficiencies. Though the boiler had the highest avoidable and inevitable exergy losses 〖(ĖL〗_AVO and 〖Ėx〗_INE) respectively, Heater 3 showed the most potential for performance improvement with (158.04%). Followed by Heater 6 (54.7%), the deaerator (15.15%), the condenser (13.55%), and Heater 1 (12.62%) when we consider 〖ĖL〗_AVO/〖Ėx〗_INE . A combined pinch and exergy analysis (CPEA) gave similar outcomes, and showed further that changes in cold stream properties majorly led to performance declines observed. For improved plant performance, the exergy losses identified in the HEN should be reduce beginning from the cold streams.
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