Aimed at solving the problems of high coal consumption and economic efficiency decline occurred in direct air-cooling units running at non-optimal economic back pressure

mathematical models of unit output power increment and fan power increment were established in this article through thermodynamic calculation and mechanism analysis

and the best economic pressure was obtained via calculating the maximum increment of the unit net output. Moreover

through variable condition calculation

the economic back pressure form and its fitting function for different working conditions was built up. The expert system of back pressure optimization was constructed according to the fitting curves of generating force

fan power and back pressure. The sequential control logic of the segmented antifreeze protection was designed to meet the requirements of freezing protection in the aircooled island in winter. The actual engineering results show that

after the proposed air-cooled island optimization system was applied

the coal consumption for power supply decreased by 1.556 g/(kW·h)

indicating the unit economy was improved

and the antifreeze protection action was sensitive and effective.