高硫石油焦燃烧过程中不同赋存形态钒的变迁行为研究

采用逐级化学提取结合ICP-OES方法,研究了高硫石油焦燃烧过程中重金属元素钒的赋存形态和迁移转化行为,并结合热力学分析方法,探讨了其化学反应机理。石油焦中钒的赋存形态主要为有机质结合态和稳定态。随着燃烧温度的升高,有机质结合态的钒发生快速分解直至消失,且与Ca、Na、Fe和K等矿物质反应,转化为水溶态和部分离子可交换态、碳酸盐结合态、氧化物结合态钒。稳定态钒主要是与其他矿物质形成非晶态结构物质存在于石油焦中,在高温燃烧过程中,会部分熔融转化并释放出少量的钒。石油焦中钒的挥发性随着燃烧温度和燃尽率的升高逐渐增大,且呈现阶段性挥发的特点。温度高于1100℃,有机质结合态的钒快速分解,且部分转化为具有挥发性的VO2等化合物,致使钒的挥发率急剧增大。

Migration and transformation behaviors of vanadium (V) with different occurrence modes during combustion of high sulfur petroleum coke

The occurrence modes and migration behavior of vanadium were investigated by sequential chemical extraction combined with ICP-OES during combustion of high-sulfur petroleum coke. The chemical reaction mechanism was discussed based on thermodynamic analysis. The vanadium in raw petroleum coke is mainly associated with organic matter and stable forms. With increasing temperature organic V disappear and the released vanadium could react with minerals such as Ca, K, Na, Fe to form different vanadium species including water soluble and ion exchange state, carbonates and Fe-Mn oxides. Steady-state vanadium is mainly combined with other minerals to form amorphous substance existing in petroleum coke. These amorphous substances might transform and release vanadium species at high combustion temperatures. The V volatility is correlated with temperature and burn out rate. The volatility may sharply rise because organic matter decomposed and released gaseous VO₂ above 1100℃.