煤炭地下气化特征污染物迁移行为探测

煤炭地下气化潜在的地下水污染风险,是煤炭地下气化产业化的关键技术及瓶颈技术。采用直接钻探法对我国首个钻孔式地下气化炉进行了燃空区探测,并对不同气化区域的煤、岩、半焦、灰渣样品进行了取样。开展了探测样品的浸出实验,研究了浸出液中特征气化污染物及污染指标挥发酚、氨氮及COD的迁移范围及迁移特征,探讨了污染物的迁移路径。研究结果表明,特征污染物的迁移主要发生在中心气化区内,挥发酚及氨气在煤层顶板内发生了垂直向上的迁移,煤层顶板垮落带及裂隙带是污染物迁移的主要通道。污染物向底板岩层渗透迁移的倾向极低。在气化边界区域,煤层顶板内没有形成污染物迁移通道,未发现污染物向围岩的迁移。气化煤田的科学选址是煤炭地下气化地下水污染防治的重要环节。

Migration behavior of typical pollutants from underground coal gasification

The control of groundwater contamination is the key technology in underground coal gasification (UCG) since the potential contamination risk has become the bottleneck for UCG commercialization.In this study,based on the drilling exploration of a field test of UCG,the samples of coal,char,ash,slag and rock along the drilling boreholes were obtained,then the leaching experiment of samples were performed.Moreover,the migration behavior of the typical pollution indicators,volatile phenols,ammonia nitrogen and COD were analyzed,and the migration path of pollutants was also discussed.The results show that the migration of typical pollutants mainly occurs in the center of gasification zone and their vertical migration along the roof are found.The caving zone and fractured zone in the roof provide the main channel for contaminant migration.The tendency of pollutants migration toward the floor rock through permeation is very low.Near the gasification boundary,no migration path is formed in the roof of the coal seam,and the pollutant migration is not detected.The scientific site selection of the gasification coal field is the most important step for UCG pollution control.