Energy Performance Benchmarking and Improvement of Pneumatic Conveying Systems in Flour Milling Plants in Kano State

Pneumatic conveying systems are integral to the flour milling process chain in Nigerian food processing facilities, transporting grain, semolina, and flour between processing stages, yet they are among the most energy-inefficient bulk material handling technologies deployed in the industry and represent significant targets for energy performance improvement. This study benchmarks the energy performance of pneumatic conveying systems in three large-scale flour milling plants in Kano State and develops validated improvement recommendations. An engineering audit of conveying systems was conducted at each plant, measuring conveying air velocities, operating pressures, air flow rates, blower power consumption, material throughput rates, and pipe bore and routing configurations. Specific energy consumption expressed as kilowatt-hours per tonne conveyed was calculated and benchmarked against published flour milling industry performance data. Dense-phase conveying feasibility was assessed for selected high-volume transfer lines currently operating in dilute-phase mode. EDEM discrete element method simulations were conducted to evaluate particle-air interaction behaviour under dense-phase conditions for the flour properties measured. Results showed that specific energy consumption at the three plants ranged from 8.2 to 13.4 kilowatt-hours per tonne, significantly exceeding the industry benchmark range of 4 to 6 kilowatt-hours per tonne for well-designed systems. Conversion of the five highest-volume transfer lines to dense-phase conveying was estimated to reduce conveying energy consumption by 38 to 52 percent, with payback periods of 14 to 22 months. Keywords: pneumatic conveying, energy benchmarking, flour milling, dense-phase conveying, Kano State.