煤层地下气化腔粉煤灰矿化封存CO2研究

Study on CO₂ sequestration via fly ash mineralization in underground coal gasification cavities

摘要:

为应对全球碳排放与工业固废处理的双重挑战，本文提出一种基于煤层地下气化（UCG）废弃空腔与粉煤灰矿化封存相结合的“碳封存-固废处置-废弃空腔利用”三位一体工程方案。采用CMG-STARS软件构建三维三相五组分耦合模型，模拟粉煤灰浆体注入与CO?注入过程中的热力学与矿化反应行为，重点分析不同CO?注入速率对温度场演化及封存效率的影响。研究结果表明：提高CO?注入速率可显著增强矿化反应强度与空间均匀性，将速率从20000 m3/d提升至60000 m3/d，相同总注入量的矿化封存效率提高约15%；注入的低温CO?引起初期降温，但矿化放热效应逐步逆转该趋势，使温度最终稳定在250 ℃左右。本研究为发展“碳封存-固废处置-废弃空腔利用”三位一体的工程技术提供了理论依据与参数优化策略。

Abstract:

To address the dual challenges of global carbon emissions and industrial solid waste disposal， this study proposes an integrated "carbon sequestration-solid waste disposal-abandoned cavity utilization" three-in-one engineering scheme. This scheme combines abandoned cavities from Underground Coal Gasification （UCG） with fly ash mineralization for CO₂ sequestration. Using CMG-STARS software， a 3D， three-phase， five-component coupled model was developed to simulate the thermodynamic and mineralization behaviors during the injection of fly ash slurry and CO₂. The study focused on the effects of different CO₂ injection rates on temperature field evolution and sequestration efficiency. The results indicate that increasing the CO₂ injection rate significantly enhances the intensity and spatial uniformity of the mineralization reaction. For the same total injection volume， increasing the rate from 20000 m3/d to 60000 m3/d improves the sequestration efficiency by approximately 15%. While the injection of low-temperature CO₂ initially causes a cooling effect， the exothermic nature of the mineralization reaction gradually reverses this trend， stabilizing the temperature at approximately 250 ℃. This study provides a theoretical basis and parameter optimization strategies for the development of this integrated engineering technology.