Energy and exergy analysis of a new calcium carbide production process

Energy and exergy analysis is very useful to optimize the design, operation and evaluation of calcium carbide production process. In this paper, a new calcium carbide production process of coal-coke-electricity grading substitution method (GSM) is proposed and evaluated by inter grating the first and second laws of thermodynamics according to the actual operation data from an actual calcium carbide production enterprise. Three typical calcium carbide production processes of GSM, electro thermal method (ETM) and oxygen thermal method (OTM) are compared based on the comprehensive energy and exergy consumption indexes of multiple products. The results show that, for the GSM, the mixed pellet brings into the highest proportion of energy and exergy of 69.36% and 71.85%, while the calcium carbide brings out the highest proportion of energy and exergy of 71.97% and 69.09%. Among the various heat losses, calcium carbide furnace gas takes the most heat, accounting for 15.9% of the total heat output. The power consumption per unit product of GSM is only 2.48 kWh/kg-CaC2, which is 23.93% lower than 3.26 kWh/kg-CaC2 of ETM. According to the energy and exergy analysis, when CaC2 is the only target product, the GSM has the lowest comprehensive energy consumption of 10.22 kWh/kg-CaC2 and the lowest comprehensive exergy consumption of 9.15 kWh/kg-CaC2. Compared with the traditional ETM and OTM, the GSM has obvious advantages.