Effect of moisture content on gas release and pore structure development of wetted Shenfu coal during rapid pyrolysis
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摘要: 通过外添加水分改变神府煤含水量，利用高频加热炉进行快速热解，研究了含水量对神府煤快速热解过程的影响，考察了四种含水量神府煤快速热解气相产物分布及变化规律，利用孔/表面分析仪表征了固相产物的结构变化。结果表明，随着煤中含水量升高，热解气总体积和最大释放速率减小；热解焦的比表面积和孔容随含水量升高而增大，与原煤煤焦相比，含水煤制得热解焦中保留了较多小孔，孔隙结构更加发达；水分有利于抑制热解过程孔的阻塞与塌陷，提高煤焦表面的粗糙程度和多孔结构的复杂程度。Abstract: The rapid pyrolysis experiments of Shenfu coal with various moisture content prepared by adding water were conducted in a high-frequency furnace to study the influence of moisture content on the thermal behavior. The gas composition and the structure properties of char were analyzed. The result shows that the gas yield and the maximal release rate decrease when the moisture content of coal increases. After pyrolysis, both BET surface and pore volume increase with increasing moisture. Compared to the char from dry coal pyrolysis, the char from pyrolysis of coal with high moisture content has more developed pore structure with more micropores. Furthermore, the moisture can inhabit the occurrence of pore obstruction and collapse during rapid pyrolysis, and also contribute to the enhancement of the surface roughness and the pore structure complexity.
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Key words:
- wet coal /
- rapid pyrolysis /
- gas release /
- pore structure
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图 2 不同含水量神府煤1 573 K快速热解过程质量收率
Figure 2 Mass yield of char for Shenfu coal rapid pyrolysis at 1 573 K with varied moisture content
图 3 第一阶段 (stage 1) ln (Ys-1) 与t的关系
Figure 3 Relation between ln (Ys-1) and time at stage 1(dehydration)
图 4 不同含水量神府煤快速热解气体释放
Figure 4 Gas release rate of different wetted coals during pyrolysis
(a): SF-coal (0); (b): SF-coal (9%); (c): SF-coal (17%); (d): SF-coal (23%)
图 5 热解气体释放量随固体质量收率变化
Figure 5 Relation between gas yield and mass char yield
(a): H2; (b): CH4; (c): CO
图 6 热解气体总体积及释放速率
Figure 6 Variation of pyrolysis gas volume and release rate
(a): variation of pyrolysis gas volume; (b): release velocity of pyrolysis gas volume
图 7 SF-coal (23%) 及煤焦吸附-脱附等温线
Figure 7 Adsorption/desorption isotherms of SF-coal (23%) and chars
(a): SF-coal (23%); (b): SF-150-23%; (c): SF-450-23%
图 8 含水神府煤制得热解焦平均孔径 (APS) 及比表面积 (BET) 的变化
Figure 8 Variation of char average pore size and BET surface area of wetted coal during pyrolysis
(a): SF-coal (0) and chars; (b): SF-coal (9%) and chars; (c): SF-coal (17%) and chars; (d): SF-coal (23%) and chars
图 9 含水神府煤及热解焦的孔径分布
Figure 9 Pore size distribution of Shenfu coal wetted and pyrolysis chars
(a): SF-coal (0) and pyrolysis chars; (b): SF-coal (23%) and pyrolysis chars
图 10 不同含水量神府煤热解前后孔长变化比例
Figure 10 Variation of the pore length of different moisture content coal
图 11 SF-coal (0) 样品吸附曲线FHH拟合
Figure 11 Plots of ln V vs ln (ln (p0/p)) reconstructed from the N2 gas adsorption isotherms
表 1 干燥后神府烟煤的工业分析和元素分析
Table 1 Proximate and ultimate analysis of Shenfu bituminous coal
Coal sample Proximate analysis wd/% Ultimate analysis wd/% V FC A C H N S O* SF-coal 35.48 59.06 5.46 72.87 3.88 1.01 0.17 16.61 *: by difference 
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表 2 神府煤及煤焦颗粒粒径平均值
Table 2 Average particle size of Shenfu coal wetted and chars
Moisture content Particle size d/μm 0 9% 17% 23% Coal 127.1 128.4 129.9 131.6 Char 109.1 109.0 109.2 109.0 Average 118.1 118.7 119.6 120.3
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表 3 煤颗粒在不同长度恒温区中停留时间
Table 3 Residence time of the coal particles at different length of hot zones
Moisture content Residence time at different length of hot zones t/ms (T=1 573 K) 30 mm 60 mm 120 mm 150 mm 180 mm 210 mm 270 mm 300 mm 330 mm 360 mm 450 mm 0 147 293 587 733 880 1 027 1 320 1 466 1 613 1 760 2 200 9% 145 290 581 726 871 1 017 1 307 1 452 1 598 1 743 2 179 17% 143 286 573 716 859 1 002 1 289 1 432 1 575 1 718 2 148 23% 141 283 566 707 849 990 1 273 1 414 1 556 1 697 2 121
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表 4 含水量神府煤及部分热解焦的水分形态
Table 4 Moisture form of Shenfu coal wetted and chars
Sample Mf, ar/% Minh, ar/% Mar/% Sample Mf, ar/% Minh, ar/% Mar /% SF-coal (9%) 7.07 1.97 9.04 SF-180-17% 1.57 0.93 2.50 SF-coal (17%) 15.09 1.93 17.02 SF-450-17% 0 0.01 0.01 SF-coal (23%) 21.01 1.87 22.88 SF-270-23% 3.73 1.81 5.54 SF-450-9% 0 0.01 0.01 SF-300-23% 1.42 0.89 2.31 SF-150-17% 3.96 1.84 5.80 SF-450-23% 0 0.02 0.02
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