Distribution of alkaline (earth) metals and gasification reaction characteristics of HSQ coal under CO2/H2O atmosphere
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摘要: 使用高温气化固定床实验系统开展了CO2/H2O气化条件下,红沙泉煤中碱(土)金属(AAEMs)的分布情况及其对煤焦气化反应活性的影响。结果表明,气化温度低于灰熔点温度时,Na元素在煤焦表面离散分布,不存在明显的团簇富集现象;气化温度高于灰熔点温度时,Na元素在煤焦表面表现出轻微的富集现象。气化过程中K元素离散分布在煤焦表面,Ca和Mg元素在煤焦表面的富集现象比较明显,含Ca、Mg类矿物迁移团簇在煤焦表面凹陷处,形成尺寸较大的灰球,Ca、Mg元素在分布上存在一定的依赖性。气化残余焦的表观活化能和指前因子随着碳转化率的增加而增加,煤焦的反应活性变低。Abstract: The distributions of Hongshaquan coal's alkaline (earth) metals and their influence on coal char gasification reaction activity under different gasification conditions were investigated in a high-temperature gasification fixed-bed experimental system. The results showed that the Na discretely distributed on the char surface at low temperature, while it showed a slight aggregation phenomenon when the gasification temperature was higher than ash fusion temperature. During the gasification process, the K was evenly distributed on the char surface. The enrichment of Ca and Mg elements on the surface of coal char was relatively obvious. The migration clusters of calcium-containing and magnesium-containing minerals formed large-sized ash sphere in the depressions on the surface of coal char. There was a certain dependence on the distribution of the above two elements. As the carbon conversion increased, the apparent activation energy and pre-exponential factor all increased, and the reactivity of coal char became worse.
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Key words:
- Hongshaquan coal /
- gasification /
- CO2/H2O atmosphere /
- alkali (earth) metal /
- coal char
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表 1 红沙泉原煤的工业分析和元素分析
Table 1 Proximate and ultimate analyses of HSQ coal
Proximate analysis wad / % Ultimate analysis wad / % M A V FC Fuel ratio Qnet, ad /(kJ·kg−1) C H O N St, 14.63 7.52 32.82 45.03 1.37 21358.40 61.52 3.59 11.48 0.84 0.42 Notes: M, A, V and FC are the moisture mass fraction, the ash mass fraction, the volatile matter mass fraction and the fixed carbon mass fraction of sample, respectively; ad is air dry basis 表 2 CO2/H2O复合气氛下气化残余焦的动力学参数
Table 2 Kinetic parameters of gasification residual coke under CO2/H2O composite atmosphere
t /℃ x /% E /(kJ·mol−1) A / ×1011 min−1 R2 1000 30 291.62 2.33 0.993 50 316.88 25.82 0.995 70 328.73 654.95 0.988 1100 30 306.03 6.45 0.991 50 322.51 19.88 0.993 70 350.88 329.46 0.994 1200 30 359.51 969.17 0.993 50 376.55 4656.28 0.993 70 387.04 15062.5 0.992 1300 30 380.21 2672.68 0.992 50 385.83 4999.62 0.988 70 392.50 5658.3 0.984 -
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