铁浴造气过程中硫的行为—PPEC程序包在冶金计算中的应用

SULFUR BEHAVIOUR IN THE PROCESS OF COAL GASIFICATION IN MOLTEN IRON BATH

根据多相多组分平衡原理,在铁浴—煤氧喷射造气条件下,对熔渣的组成和硫在渣—铁—气三相中的分配进行了单元模化,结果表明熔渣组元主要以复合化合物存在,高碱度的熔渣是获得低硫铁水和低硫煤气的主要条件.动力学分析和试验结果表明,气—铁间硫的分配接近热力学平衡,而渣—气间硫的分配远离热力学平衡,硫在渣中的传质是造气过程中渣—铁—气三相平衡的限制环节.

A unit simulation of sulfur behavior and the structure of molten slag is conducted for the process of coal gasification by injection into molten iron bath with oxygen. The structure of molten slag and sulfur equilibrium partition among molten iron, molten slag and coal gas are calculated based on the principle of multiphase and multicomponent chemical equilibrium. The results show that the components of slag (for example CaO, MgO, SiO_2) are mainly exist in complex forms (for example, CaO·SiO_2, CaO·Mgo·SiO_2, 3CaO·MgO·2Sio_2). To make high basicity slag is the main condition for producing high quallity iron and coal gas of lower sulfur content. Besides, the sulfur content in molten iron decreases with the increaasing temperature and H_2 content in coal gas. High pressure operation is unfavorable for obtaining iron with low sulfur content. The sulphide in coal gas is in form of CS, H_2S and little COS. The kinetics of sulfur transfer among gas, molten slag and molten iron is analyzed based on the experimental results of sulfur content obtained in a 100 kg industrial furnace by coal-oxygen bottom injection into carbon saturated liquid iron. The experimental and calculated results show that the sulfur partitions is nearly in equilibrium between hot iron and coal gas, but is far away from equilhbrium between slag and coal gas. The sulfur transfer in slag is the controlling step for sulfur partition in the slag-metal-gas system. The content of sulfur in molten slag decreases during coal injection process, and the content of sulfur in liquid iron also decreases with the increase of injection rate when the overall amount of coal injected is kept constant.