Energy, exergy, sustainability, and emission analysis of industrial air compressors

Abstract

As industrial air compressors are the most energy intensive, a comprehensive energy and exergy analysis, reducing energy usage by various energy savings measures are highly important to reduce their energy consumption and emission for the sustainable future growth. A comprehensive analysis on energy performance, exergy efficiency, CO2 emission, sustainability, and the associated economic implications were studied in a typical industrial air compressor system of a TiO2 manufacturing industry, located in Bahia, Brazil. Necessary input data were taken from this industry to analyze energy, exergy, emission, economic, and sustainability performance of the air compressor. The predicted overall exergy efficiency of the compressors varies from to 5.27%–21.94%. Sustainability indicators like Sustainability Index (SI), Depletion Number (DN), Waste Exergy Ratio (WER), & Environmental Effect Factor (EEF) were analyzed and the evaluated sustainability index found to vary from 1.05 to 1.28. Waste exergy ratio is estimated to be 0.95 and environmental effect factor is found to be 17.95 for compressor A. Discharge pressure reduction, power factor improvement, waste heat recoveries are the main areas where improvement have been identified. Reducing discharge pressure can save annually 3515.180 MWh of electricity leading to a reduction of 347.7 ton of CO2 emission per year. It is also noted that the reduced discharge pressure lead to an increased exergetic efficiency. Among various options, reducing discharge pressure came out to be the most cost effective measure with lesser internal rate of return. The industry could save a total of 5634.2 MWh of electricity and reduce CO2 emission by 557 ton per annum with an investment of US$ 570,000. The return on investment for the investment is estimated to be 9 months.