Promoting effect of oxidation reaction on steam gasification reaction in Shengli lignite gasification process Ⅰ: Macroscopic reaction characteristic
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摘要: 在φ80×3 000 mm耐高温不锈钢管气流床反应器中，以150-180 μm胜利褐煤为气化原料，考察了800和900℃时添加氧气前后褐煤转化率的变化，研究了氧化反应对水蒸气气化反应影响的宏观特征。结果表明，添加氧气后褐煤转化率明显大于O2和H2O气氛下褐煤转化率之和，即向水蒸气气氛添加氧气后褐煤转化率的增幅大于氧气氧化作用导致的褐煤转化率的增幅，随着H2O含量增大以及温度的升高此现象愈加明显。该协同作用主要是氧化反应对水蒸气气化反应的促进作用造成的。利用φ40×200 mm石英圆筒流化床反应器进行了类似的实验，也发现了该协同作用。同时，借鉴收缩核模型并结合气流床气化实验条件推导了水蒸气气化宏观动力学方程，得到的速率方程$ (Z-{{(1-x)}^{\frac{1}{3}}})=\frac{t\beta {{k}_{{{\text{H}}_{2}}\text{O}}}}{R{{\rho }_{\text{C}}}}{{\varphi }_{{{\text{H}}_{2}}\text{O}}}={{K}_{{{\text{H}}_{2}}\text{O}}}{{\varphi }_{{{\text{H}}_{2}}\text{O}}} $与实验值吻合较好，添加氧气后水蒸气气化反应速率和水蒸气气化反应表观速率常数KH2O明显增大，这是氧气对水蒸气气化反应促进作用的动力学特征。Abstract: Shengli brown coal in 150-180 μm was gasified at 800-900℃ in a simulated entrained-flow reactor, φ80×3 000 mm. Conversion and kinetics of steam gasification reaction of the lignite were discussed to investigate synergistic effects of oxidation reaction on steam gasification reaction. The results show that lignite conversion under H2O+1%O2 atmospheres is greater significantly than the sum of that under H2O atmosphere and 1%O2 atmosphere, i.e., the increase of lignite conversion from H2O atmosphere to H2O+1%O2 atmospheres is greater than that from N2 atmosphere to N2+1%O2 atmospheres. The synergistic effects are caused by promoting effect of oxidation reaction on steam gasification reaction, and are more obvious as H2O content increasing and temperature rising. Moreover, the similar experiments were carried out in φ40×200 mm cylindrical quartz fluidized bed, and the synergistic effects are also found. The steam gasification reaction rate equation, $ (Z-{{(1-x)}^{\frac{1}{3}}})=\frac{t\beta {{k}_{{{\text{H}}_{2}}\text{O}}}}{R{{\rho }_{\text{C}}}}{{\varphi }_{{{\text{H}}_{2}}\text{O}}}={{K}_{{{\text{H}}_{2}}\text{O}}}{{\varphi }_{{{\text{H}}_{2}}\text{O}}} $, is in good agreement with experimental data. This indicates that the apparent rate constant KH2O increases obviously after O2 adding to water vapor, which is the kinetic characteristics of promoting effect of oxidation reaction on steam gasification reaction.
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Key words:
- mild gasification /
- synergistic effect /
- steam gasification /
- conversion rate /
- kinetics
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图 2 800 ℃时向水蒸气气氛中添加1%氧气前后褐煤转化率的变化
Figure 2 Coal conversion as a function of steam concentration in H2O and H2O+1%O2 atmospheres at 800 ℃
图 3 900 ℃时向水蒸气气氛中添加1%氧气前后褐煤转化率的变化
Figure 3 Coal conversion as a function of steam concentration in H2O and H2O+1%O2 atmospheres at 900 ℃
图 4 在800 ℃流化床反应器中向水蒸气中添加0.15%O2前后褐煤转化率的变化
Figure 4 Relation of coal conversion with steam concentration in H2O and H2O+0.15%O2 atmospheres at 800 ℃ in gas fluidized bed
图 5 在800 ℃流化床反应器中向水蒸气中添加0.60%O2前后褐煤转化率的变化
Figure 5 Relation of coal conversion with steam concentration in H2O and H2O+0.60%O2 atmospheres at 800 ℃ in gas fluidized bed
图 6 在800 ℃流化床反应器中向水蒸气中添加1.50%O2前后褐煤转化率的变化
Figure 6 Relation of coal conversion with steam concentration in H2O and H2O+1.50%O2 atmospheres at 800 ℃ in gas fluidized bed
图 7 利用实验数据计算的水蒸气气氛下水蒸气气化反应表观速率常数KH2O值
Figure 7 Values of KH2O apparent rate constant of steam decomposition reaction
图 8 向水蒸气气氛中添加氧气前后水蒸气气化反应表观速率常数KH2O值的变化
Figure 8 Values of KH2O apparent rate constant of steam decomposition reaction in H2O and H2O+1%O2 atmospheres
表 1 胜利褐煤的工业分析和元素分析
Table 1 Proximate and ultimate analysis of material
Material Proximate analysis wad/% Elemental analysis wdaf/% M A V FC C H S O N Shengli lignite 5.89 9.87 36.23 53.90 62.26 6.12 0.66 29.85 1.11 
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