Thermal analysis to investigate the effects of operating parameters on conventional cupola furnace efficiency

Abstract

Background: Thermal analysis was performed on a conventional 6.5 m high dome with a 0.65 m diameter at Nigeria Railway Corporation. Energy and thermal analyses were performed on the furnace to improve efficiency and minimize energy losses in the system. Results: The energy efficiency recorded was 55%. The losses in the furnace amount to 45%, the highest value being the heat loss to the combustion gas at 34%. A parametric study was examined to see the effect of some design and operational parameters on furnace efficiency through energy savings and the study found a positive trend. The parameters include the flue gas temperature, the combustion air inlet temperature, the thickness, and the emissivity of the refractory wall. A decrease in the temperature of the flue gases increased the efficiency of the furnace to 73%, an increase in the air inlet temperature increased the efficiency of the furnace to 61%, and an increase in the thickness of the refractory wall increased the efficiency of the furnace. Oven to 56% and a decrease in emissivity of the refractory wall increased the efficiency of the furnace to 56%. Conclusions: The studied parameters were further combined and their net effect showed a possible increase in furnace efficiency from 55% to 78%. The maximum efficiency of 78% was determined with respect to the minimum/maximum estimated values of the parameters studied, as more metals are melted with the combined energy saved from a variation of these parameters. This implies that cupola furnace or similar furnace designers or operators should be guided on the preheating conditions, thickness, and emissivity of the refractory wall to be used with other parametric combinations to be adopted to ensure energy efficiency and improvement in such furnaces.