Energy savings and emission reductions in industrial boilers

Abstract

In this paper energy use of boiler fan motors has been estimated using energy audit data. Energy savings using VSD by modulating fan speed has been estimated as well. Bill savings and associated emission reductions using VSD have been estimated and presented in this paper. It has been found that 139,412 MWh, 268,866, 159,328 MWh, and 99,580 MWh electrical energy can be saved for 40%, 60%, 80% and 100% motor loadings, respectively for 60% speed reduction. Corresponding bill savings for the aforementioned energy savings have been found to be US$7,318,335, US$14,113,933, US$8,363,812, and US135,911,944 for 40%, 60%, 80% and 100% motor loadings, respectively for 60% speed reduction. Along with energy savings, 69,770,744 kg, 134,558,329 kg, 79,738,065 kg, 49,836,603 kg of CO2 emission can be avoided for the associated energy savings as a result of energy savings using VSD for 40%, 60%, 80% and 100% motor loadings. Moreover, 32,503,558 GJ of fossil fuel can be saved for the flue gas temperature reduction as a result of reducing fan motor speed reduction. Flue gas energy savings for oxegen trim system has been estimated and found to be 549,310,130 GJ for 16.9% of excess air reduction with payback period less than a day.