Evaluation of Industrial Boiler Efficiency and Decarbonisation Potential in Food and Beverage Plants in Oyo State

Industrial boilers in Nigerian food and beverage manufacturing plants represent some of the highest energy cost centres and carbon emission sources in the manufacturing sector, yet systematic efficiency benchmarking studies for this sector in Oyo State, South West Nigeria, are absent from the literature. This study evaluates the thermal efficiency of eight industrial steam boilers operating in food and beverage plants in the Ibadan industrial zone using the indirect method based on heat loss analysis. Combustion flue gas composition, stack temperature, feed water temperature, steam output, and fuel consumption data were measured over five working days at each plant. Boiler efficiency was calculated in accordance with ASME PTC 4.1 guidelines. Decarbonisation potential was assessed by modelling the substitution of heavy fuel oil with biomass pellets from agricultural residues available in Oyo State. Measured boiler efficiencies ranged from 62.8% to 81.3%, with an average of 72.4%, significantly below the international benchmark of 85 to 88% for well-maintained modern industrial boilers. The dominant heat loss mechanisms were dry flue gas losses and unburnt losses in flue gas. Switching from heavy fuel oil to compressed natural gas could reduce carbon dioxide emissions by an average of 23% per plant, while biomass pellet co-firing at 30% substitution offered an additional 18% emission reduction. The study provides a baseline energy audit framework for industrial boiler improvement in Oyo State food and beverage manufacturing. Keywords: boiler efficiency, heat loss, decarbonisation, food and beverage, Oyo State