氧气对胜利褐煤水蒸气气化半焦结构及反应性的影响

为了研究氧气对半焦的结构变化和反应性的影响,采用不锈钢模拟气流床反应器,在8种不同气氛,800和900 ℃条件下,进行了胜利褐煤水蒸气气化实验。利用拉曼光谱和热重分析仪分别表征了半焦的结构和本征反应性。结果表明,在800和900 ℃条件下,添加的氧气对半焦结构变化的影响方式不同;半焦结构的变化是影响碱金属和碱土金属(AAEM)挥发的主要因素。在不同温度下,添加的氧气对Na挥发的影响和对结构的作用类似,H₂O/O₂混合气氛促使气化所得半焦的反应性进一步降低。半焦的反应活性指数与拉曼光谱谱带比值 I (G_R+V_L+V_R)/I_D具有很好的相关性。

Effects of oxygen on the structure and reactivity of char during steam gasification of Shengli brown coal

The effects of oxygen on changes in char structure and reactivity during steam gasification of Shengli brown coal were examined. A stainless steel simulated entrained-flow reactor was employed to carry out gasification at 800 and 900 ℃ in 8 atmospheres: pure N₂, 15% H₂O, 25%H₂O and 35%H₂O balanced with N₂; and 1%O₂, 15%H₂O+1%O₂, 25%H₂O+1%O₂ and 35%H₂O+1% O₂ balanced with N₂. The structure of chars was measured by Raman spectrum, and the intrinsic reactivity of chars with air was measured using a thermogravimetric analyzer (TGA) at low temperature (300 ℃). The results show that the effects of oxygen on char structure are different at high temperature (900 ℃) and low temperature (800 ℃) in brown coal steam gasification. The volatilization of alkali and alkaline earth metallic (AAEM) is strongly influenced by char structure. The presence of O₂ during steam gasification has a similar effect on the volatilization of Na to the evolution of structure at different temperatures. Experimental data provided evidence that a mixed H₂O/O₂ atmosphere could promote a decrease in subsequent char reactivity in air at 300 ℃, and that char reactivity could correlate well with the band area ratio, I_(GR+VL+VR)/I_D.