A Novel Coal-Based Calcium Carbide-Acetylene System Process Based on Multistage Carbon Capture and Waste Slag Recycling Design: A Multiobjective Optimization Evaluation Perspective

Large amounts of raw material consumption, high energy consumption, and severe pollution have always been the key factors restricting the stable development of the coal-to-calcium carbide industry. Therefore, this paper presents a novel combined carbon capture and utilization and solid waste recycling system of the coal-based calcium carbide-acetylene production (CCAP) process to improve these deficiencies. This improved CCAP system consists of a gasifier, carbide furnace, acetylene furnace, the newly designed coupling module of a recarbonization furnace and calciner, and mineralization units. The thermodynamic model of the CCAP system is developed to calculate the effective atomic yield, carbon consumption, CO₂ emission, etc. to evaluate the performance. The improved system performed better with the effective atomic yield (98.50%), CO₂ capture rate (69.57%), CO₂ emission (1.1064 t CO₂·(t^-1C₂H₂)), CO₂e emission (7.2092 t CO₂e·(t^-1C₂H₂)), and carbon consumption (3.2101 t Coal·(t^-1C₂H₂)) than the referenced system with 64.57%, 0, 2.25 t CO₂·(t^-1C₂H₂), 20.4122 t CO₂e·(t^-1C₂H₂), and 5.43 t Coal·(t^-1C₂H₂), respectively. The exergy analysis shows that the improved system performed better for efficient energy utilization with an exergy efficiency of 48.97% for a large-scale chemical process. Besides, the trade-off between the maximum effective atomic yield, minimum carbon consumption, CO₂ equivalent emission, and total annual cost (TAC) is conducted through multiobjective optimization. By three-objective optimization, the improved system could achieve a lower TAC of 8.51 × 10⁶ $/year, CO₂e emission of 4.1573 t CO₂e·(t^-1C₂H₂), and carbon consumption of 1.9874 t Coal·(t^-1C₂H₂) simultaneously, which decreased by 38.78%, 79.63%, and 63.40%, respectively, than that of the referenced system. The all-around performance of the improved CCAP system after multiobjective optimization has been dramatically improved, making it more competitive in energy conservation, emission reduction, and resource recovery.