Investigations on the energy efficiency limits for industrial boiler operation and technical requirements—taking China's Hunan province as an example

Highlights: • Investigated the operation status of the industrial boilers in Hunan Province. • Obtaining an importance ranking of the corresponding key factors. • Supposed industrial boiler energy efficiency standards for Hunan Province. Specially tailored energy efficiency standards are critical for the energy-saving of local industrial systems. We take the Hunan province as a concrete example, and select its industrial boiler as the study subject based on the survey results of Hunan's leading industrial structure. Effective energy and exergy quantitative analysis methods were applied to obtain the efficiency of the target industrial boilers. Combining the corresponding reference standards with the exergy & thermal efficiency, the analytic hierarchy process, and uncertainty analysis results, we propose a reasonable regional industrial boiler energy efficiency standard. Additionally, the main factors affecting the industrial boiler system were distilled and ranked: 1-exhaust gas temperature, 2-fuel volatile matter, 3-air coefficient, 4-boiler capacity, 5-cold air temperature, 6-slag carbon content, 7-slag temperature. These results could provide a theoretical foundation for designing further energy-saving renovation projects of the industrial boiler system.