Carbon-Calcium Composite Conversion Calcium Carbide Acetylene System: Material and Energy Transformation, Exergy Evaluations

Calcium carbide is one of the important basic coal chemical products in China. Oxy-thermal method is a potential alternative to electro-thermal method to overcome the disadvantages of high energy consumption, high material consumption, and high pollution. However, the traditional oxy-thermal method is in the laboratory research stage due to the constraints of high carbon consumption, low utilization rate of solid waste and immature technology. Therefore, a novel system of carbon-calcium compound conversion for calcium carbide-acetylene production, which couples carbon capture and calcium carbide waste slag reuse process to achieve CO₂ enrichment and calcium cycle, is proposed in this paper. Based on the simulation data, the system is comprehensively evaluated by material conversion, energy utilization, exergy analyses. It is found that the proposed coupling process has the largest effective atom yield of carbon, hydrogen, and calcium, which is 85.41%. In addition, the coupling module of this process can recycle the solid waste carbide slag and the carbon capture rate is more than 90%. It is worth noting that the unit product carbon consumption of proposed system is 2.02 t Coal·t^-1 C₂H₂, which is only 0.37 times that of the traditional process. Moreover, although the 43.21% exergy efficiency of the proposed system with steam gasification agent is slightly lower than the 49.37% of traditional system, it was considered that the former is a relatively superior process because of its comprehensive better performance than the latter. From above, the proposed system is high-efficiency, low-carbon and clean for calcium carbide-acetylene production, which could be a promising process as innovative technology for carbon emission reduction in practical applications.