高碱煤自身灰捕捉碱金属特性的实验与量化

Quantum Chemistry Calculation and Experimental Study on the Characteristics of High Alkali Coal Ash Capturing Alkali Metal

基于高碱煤自身灰能够捕捉煤中碱金属这一行为特性,模拟实验探究自身灰与高碱煤反应过程的元素迁移及物相变化,结合量子化学计算对煤灰反应矿物质钠长石的反应活性进行研究,进而为实际工业锅炉燃煤控制与改善提供理论指导。结果表明:自身灰对于高碱煤中碱金属元素具有良好的捕捉效果,利用自身灰解决高碱煤沾污结渣问题具有较高的可行性;自身灰捕捉高碱煤中的Na元素主要赋存于霞石、钠长石等矿物质中,不同温度条件下,Na元素的迁移特性不同;煤灰矿物质钠长石的反应活性较高,易与亲电体系反应,其最高占据轨道几乎完全是由氧原子的2p轨道组成,Al-O键的键长较长,更容易发生断裂参与体系成键。

In consideration of the capturing alkali metal characteristics of high alkali coal ash,the phase change and element migration in high alkali coal were studied by experimental simulations when the reaction between high alkali coal and its own ash was sustaining.By virtue of the quantum chemistry theory,the physical and chemical properties of reactive coal mineral albite were calculated and analyzed in order to theoretically guide the control and improvement of practical coal combustion in industrial boilers.The results show that it is highly feasible to solve the fouling and slagging problems of high alkali coal combustion by making use of the good capturing effect of high alkali coal ash.The captured sodium is mainly deposited in coal ash minerals such as nepheline and albite,and its migration features are changeable with the variation of temperature condition.The mineral albite in coal ash has good reactive activity,and easily reacts with an electrophilic system.The highest occupied molecular orbital of albite is mainly contributed by the 2p orbital of oxygen atoms,and the length of Al-O bond in albite is longer,which primely results in the fracture and generation of chemical bonds.