Effect of particle size on gasification of char with different coal ranks
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摘要: 选取气流床气化炉所使用不同煤阶的八种煤焦,通过多级筛分制得单分散煤粉样本,利用热重分析仪考察了气化温度、煤焦粒径对不同煤阶煤焦CO2气化反应的影响。对比了不同碳转化率阶段下的反应差异,并讨论了高碳转化率阶段的情况。研究表明,随着煤阶的升高,煤焦碳微晶结构更为有序,其气化活性也随之降低。煤焦粒径对气化反应的影响与煤阶有关。对于无烟煤,平均粒径300 μm的无烟煤煤焦转化率达到95%所需时间可达40 μm煤焦的7倍;对于褐煤与烟煤,由于其孔隙结构较为发达,粒径变化对煤焦气化活性的影响并不明显。综合煤阶、气化温度、煤焦粒径对气化反应活性的影响发现,相较低阶煤,提高气化温度、减小煤焦粒径能够更有效地提升高阶煤气化反应活性。Abstract: Eight coal chars of different coal ranks were prepared to investigate the effects of coal rank, reaction temperature and particle size on char-CO2 gasification using a thermogravimetric analyzer (TGA). The variation of char-CO2 gasification rate with carbon conversion was studied, especially at high conversion stage. As a result, the crystalline structures of higher rank chars are more orderly, resulting in a lower gasification rate. For high rank coals like anthracite, the CO2 gasification rate of char with 40 μm size is about 7 times higher than that with 300 μm size to reach 95% conversion at 1 300℃. For low rank coals, particle size has little effect on the gasification rate. The results indicate that the effect of particle size on char-CO2 gasification is dependent on coal rank. The specific surface area of high rank coals is much smaller than that of low rank coals, which contributes to the significant effect of particle size on high rank coal gasification. The effect of gasification temperature and particle size on gasification rate for high rank coals is more significant than that for low rank coals.
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Key words:
- coal rank /
- gasification temperature /
- particle size /
- CO2 gasification
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表 1 煤样的工业分析、元素分析及灰熔点
Table 1 Proximate, ultimate analysis and ash fusion temperature of coal samples
Sample Proximate analysis wd/% Ultimate analysis wd/% Ash fusion temperature t/℃ V FC A C H N S O DT ST HT FT YN 55.23 39.86 4.91 59.80 4.86 0.76 0.26 29.41 1 081 1 140 1 151 1 163 NM 49.22 40.33 10.45 74.65 3.32 1.20 0.58 9.80 1 086 1 105 1 121 1 124 SF 35.42 58.29 6.29 79.14 2.32 1.12 0.77 10.36 1 152 1 167 1 175 1 179 SH 32.29 60.89 6.82 77.18 3.73 1.04 0.60 10.63 1 113 1 137 1 143 1 156 ZJX 30.19 51.58 18.23 70.23 4.28 1.19 0.34 5.73 1 458 >1 500 >1 500 >1 500 JC 5.35 78.32 16.33 78.76 1.08 0.91 1.97 0.95 1 440 >1 500 >1 500 >1 500 GZ 8.45 73.76 17.79 74.52 2.00 1.05 4.07 0.57 1 271 1 345 1 359 1 373 GP 7.96 76.81 15.23 74.59 3.03 0.91 3.12 3.12 1 342 >1 500 >1 500 >1 500 表 2 煤样的灰组分分析
Table 2 Ash compositions of samples
Sample Composition w/% SiO2 Al2O3 Fe2O3 CaO SO3 MgO Na2O TiO2 K2O SrO YN 29.17 9.40 15.29 16.17 12.89 14.29 0.47 0.49 0.06 0.09 NM 43.46 14.43 14.13 11.81 10.02 3.04 1.46 0.63 0.32 0.14 SF 44.20 18.19 11.28 15.58 5.63 1.12 1.89 0.60 0.95 0.41 SH 46.68 20.34 6.65 14.39 6.52 1.03 2.20 0.79 0.88 0.12 ZJX 58.06 34.19 2.33 0.85 0.50 0.43 0.58 1.99 0.83 0.19 GZ 50.73 31.36 8.93 1.79 1.46 1.05 0.35 2.29 1.47 0.05 JC 50.22 38.12 5.74 2.07 1.12 0.51 0.41 1.01 0.61 0.02 GP 52.85 35.43 3.95 2.32 2.39 0.72 0.16 1.18 0.75 0.06 表 3 煤样的粒径分布
Table 3 Particle size distribution of fine samples
Sample Volume average particle size d/μm < 10 μm 10-20 μm 20-50 μm 50-80 μm 80-120 μm 120-200 μm σg R2 YN 40 0 8.16 80.98 10.77 0.09 0 1.30 0.967 NM 40 0 5.56 75.22 17.76 1.47 0 1.29 0.973 SF 40 0 6.93 76.03 16.58 0.44 0 1.31 0.976 SH 40 0 2.69 77.37 18.66 1.28 0 1.29 0.968 ZJX 40 0 8.67 75.41 15.49 0.45 0 1.32 0.967 GZ 40 0 4.58 75.08 19.09 1.27 0 1.32 0.964 JC 40 0 10.65 73.51 15.48 0.33 0 1.30 0.969 GP 40 0 5.56 74.12 18.88 1.45 0 1.31 0.971 表 4 筛分煤样的σg和R2
Table 4 σg and R2 of sieved samples
Sample Volume average particle size d/μm σg R2 Sample Volume average particle size d/μm σg R2 NM 40 1.29 0.973 GZ 40 1.32 0.964 90 1.19 0.988 90 1.21 0.980 300 1.30 0.967 310 1.29 0.988 SF 40 1.31 0.976 JC 40 1.30 0.969 100 1.22 0.985 90 1.24 0.976 310 1.29 0.983 300 1.27 0.981 ZJX 40 1.32 0.967 GP 40 1.32 0.971 90 1.20 0.985 90 1.20 0.986 320 1.26 0.982 310 1.24 0.979 表 5 不同煤样的气化反应参数 (1 300 ℃)
Table 5 Reaction parameters of various chars gasification at 1 300 ℃
Sample t0.5/min t0.95/min R0.5/min-1 R0.95/min-1 r0.5, R* r0.95, R* YN 0.47 1.19 1.06 0.80 1.00 1.00 NM 0.57 1.42 0.88 0.67 1.21 1.19 SF 0.73 1.87 0.68 0.51 1.55 1.61 SH 0.76 2.12 0.66 0.45 1.62 1.82 ZJX 0.87 3.43 0.57 0.28 1.85 2.88 GZ 1.08 4.80 0.46 0.20 2.30 4.00 JC 1.16 3.60 0.43 0.26 2.47 3.03 GP 1.08 4.27 0.46 0.22 2.30 3.59 *:r0.5, R and r0.95, R is the ratio of the R0.5 and R0.95 of YN char sample to the R0.5 and R0.95 of other char, respectively 表 6 煤焦碳微晶结构参数
Table 6 Crystallite parameters of chars with different coal ranks
Sample d002 LC LC/ d002 NM char 0.373 8 0.850 9 2.276 4 SF char 0.368 1 0.878 5 2.386 8 JC char 0.363 7 1.025 3 2.819 5 表 7 不同煤样的气化反应参数
Table 7 Reaction parameters of chars at different temperatures
Sample t0.5/min t0.95/min R0.5/min R0.95/min r0.5, T* r0.95, T* NM-1 000 ℃ 1.69 4.25 0.30 0.22 3.7 3.2 NM-1 300 ℃ 0.45 1.32 1.11 0.72 SF-1 000 ℃ 2.89 8.22 0.19 0.12 4.0 5.2 SF-1 300 ℃ 0.73 1.87 0.68 0.50 ZJX-1 000 ℃ 11.59 43.49 0.04 0.02 13.3 12.7 ZJX-1 300 ℃ 0.87 3.43 0.57 0.28 JC-1 000 ℃ 21.56 111.42 0.02 0.01 18.4 31.0 JC-1 300 ℃ 1.16 3.60 0.43 0.26 *: r0.5, T and r0.95, T are the ratio of R0.5 and R0.95 at 1 300 ℃ to R0.5 and R0.95 at 1 000 ℃ 表 8 不同煤样的气化反应参数 (1 300 ℃)
Table 8 Reaction parameters of chars with different particle sizes at 1 300 ℃
Sample t0.5/min t0.95/min R0.5/min R0.95/min r0.5, P* r0.95, P* NM-40 μm 0.57 1.42 0.88 0.67 1.18 1.20 NM-300 μm 0.67 1.71 0.75 0.56 SF-40 μm 0.65 1.57 0.77 0.61 1.11 1.15 SF-300 μm 0.72 1.80 0.69 0.53 ZJX-40 μm 0.87 3.43 0.57 0.28 2.13 1.88 ZJX-300 μm 1.85 6.44 0.27 0.15 GZ-40 μm 1.08 4.80 0.46 0.20 5.94 6.55 GZ-300 μm 6.42 31.43 0.08 0.03 JC-40 μm 1.17 3.60 0.43 0.26 5.01 7.38 JC-300 μm 5.86 26.56 0.09 0.04 GP-40 μm 1.08 4.27 0.40 0.22 5.06 6.78 GP-300 μm 5.47 28.95 0.09 0.03 *: r0.5, p and r0.95, p were the ratio of R0.5 and R0.95 of 40 μm chars to R0.5 and R0.95 of 300 μm chars 表 9 不同粒径NM焦和JC焦的比表面积
Table 9 Specific surface area of NM chars and JC chars
Sample 40 μm 100 μm 300 μm NM A/(m2·g-1) 108.5 153.9 149.2 IGR /min-1 1.13 1.19 0.94 JC A/(m2·g-1) 1.96 1.78 1.50 IGR /min-1 0.39 0.29 0.13 表 10 气化反应参数对比
Table 10 Comparison of different kinetic parameters
Sample r0.5, R r0.95, R r0.5, P r0.95, P r0.5, T r0.95, T NM 1.18 1.20 1.27 1.16 3.76 3.22 SF 1.55 1.61 1.11 1.15 3.96 5.24 ZJX 1.85 2.88 2.13 1.88 13.32 12.68 JC 2.47 3.03 5.01 7.38 18.43 30.95 -
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