文摘
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°C 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°C). The results show that the effects of oxygen on char structure are different at high temperature (900°C) and low temperature (800°C) 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°C, and that char reactivity could correlate well with the band area ratio, I(GR+VL+VR)/ID.