Effect of additive iron ore on pyrolysis characteristics of a low rank coal from Hami
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摘要: 为探讨铁矿石对哈密低阶煤热解特性影响, 采用热重分析仪 (thermal gravity analysis/differential thermal gravity, TG/DTG) 和实验室固定床反应器 (fixed bed) 对哈密低阶煤进行热解实验, 研究了两种铁矿石对哈密煤热解反应性、热解气和焦油分布规律的影响。利用傅里叶红外光谱 (FT-IR) 和色谱-质谱分析仪 (GC-MS) 对焦油中官能团的变化以及焦油中物质组成进行了分析对比。结果表明, 当热解温度从室温升高至150℃时, 原煤中添加铁矿石的煤样失重速率峰逐渐向高温阶段推移; 当热解温度高于450℃时, 不同铁矿石对原煤热解的催化作用差异更加明显, 且镜铁矿>原生矿物质>赤铁矿; 当两种铁矿石添加量分别为20%时, 热解焦油和热解气都能得到较高的收率; 对于煤样HM-JT来说, 此时焦油产率为7.88%, 热解气相产物H2、CO2、CH4、CO产率与未添加镜铁矿的原煤煤样相比分别提高了4.27%、3.76%、4.39%、3.61%。对于煤样HM-CT来说, 焦油催化裂解效果一直受到铁矿石添加量的影响。在镜铁矿和赤铁矿添加量分别增加到20%的过程中, 煤样热解生成焦油的产率逐渐下降, 而轻质焦油产率和轻质焦油分数逐渐增大到6.37%、58.48%、5.34%、56.22%, 焦油中氧脱除率分别达到43.16%、36.89%。随着铁矿石的加入, 焦油中二甲苯相对含量由4.32%分别降低至3.78%、3.93%, 而甲苯相对含量由1.11%升高至1.32%、1.45%;焦油中邻甲酚和二甲酚中分子中的甲基取代基被脱除生成苯酚或甲酚, 且镜铁矿对焦油中苯系物和酚类化合物的脱甲基作用强于赤铁矿。Abstract: The effect of iron ore on pyrolysis characteristics of a low rank coal from Hami was explored.By means of thermogravimetric analyzer (TGA), fixed bed reactor, fourier transform infrared spectroscopy (FT-IR), gas chromatograph (GC) and gas chromatography-mass spectrometer (GC-MS), the changes of pyrolysis reactivity, products distribution, the functional groups in the tar and the composition of tar of three coal samples were investigated and analyzed.The results show that when the pyrolysis temperature increases from room temperature to 150℃, the peak of weight loss rate of HM-CT and HM-JT gradually moves to high temperature.When the pyrolysis temperature is more than 450℃, the catalytic effect of different iron ores on coal pyrolysis is more obvious and in the order of specularite> the inherent minerals in HM> hematite.When the two kinds of iron ores added are up to 20%, there is a higher pyrolysis tar and gas yield.The tar yield is 7.88% for HM-JT coal sample and the yield of H2, CH4, CO2 and CO increases by 4.27%, 3.76%, 4.39% and 3.61%, respectively, compared with HM coal.For HM-CT coal sample, the tar catalytic cracking is influenced by the additive amount of iron ore.As the additive amount of specularite and hematite is increasing to 20%, the yield of tar decreases gradually, while the light tar yield rises to 6.37% and 5.34%, respectively for two iron ores, and the light tar fraction increases to 58.48% and 56.22%, respectively.Besides, the removal of oxygen in tar reaches to 43.16% and 36.89%, respectively.With the addition of iron ore, the relative content of m/p-xylene in tar decreases from 4.32% to 3.78% and 3.93%, respectively for two iron ores, and the relative content of toluene increases from 1.11% to 1.32% and 1.45%, respectively.The methyl substituents of o-cresol and m/p-xylenol molecules in tar are removed to produce phenol or cresol, and the demethylation for benzene series and phenolic compounds in tar on the specularite is stronger than that on the hematite.
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Key words:
- iron ore /
- low rank coal /
- pyrolysis /
- tar /
- oxygen removal
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图 1 管式固定床热解工艺示意图
Figure 1. Schematic diagram of fixed-bed pyrolysis
1: thermocouple; 2: tube furnace; 3: quartz tube; 4: temperature controller; 5: primary condensation; 6: second condensation; 7: dryer; 8: flow meter; 9: airbag; 10: mass flow controller
图 3 600℃时原煤中添加镜铁矿 (a) 和赤铁矿 (b) 煤样热解气相产物分布
Figure 3. Pyrolysis gas product distribution of adding specularite (a) and hematite (b) in HM coal sample at 600℃
图 4 600℃时原煤和脱灰煤中添加不同量镜铁矿和赤铁矿焦油产率
Figure 4. Pyrolysis tar yield for adding specularite and hematitein HM and HM-Dem coal sample at 600℃
图 5 600℃时煤样HM-JT (a) 和HM-CT (b) 焦油产率和焦油组成随铁矿石添加量的变化
Figure 5. Pyrolysis tar yield and composition varying with the amount of iron ore added
图 6 600℃时煤样HM-JT和HM-CT与HM的热解焦油红外光谱谱图
Figure 6. Comparison of infrared analysis of pyrolysis tar for HM-JT, HM-CT and HM at 600℃
图 7 不同温度下原煤和添加铁矿石煤样热解焦油中氧元素分布
Figure 7. Oxygen content in tar from HM coal iand the coal with ron ores (hematite and specularite) added at different temperatures
图 8 600℃时不同铁矿石催化哈密煤热解焦油中的物质分类
Figure 8. Different material classification in the tar at 600℃
图 9 三种煤样热解焦油GC-MS色谱图
Figure 9. Full scan chromatograms of tar from pyrolysis of HM coal and the coals with hematite and specularite added, respectively
(a): add 20% of specularite; (b): add 20% of hematite; (c): HM raw coal
表 1 煤样的工业分析和元素分析
Table 1. Proximate and ultimate analysis of Hami coal sample
Sample Proximate analysis w/% Ultimate analysis w/% H/C O/C Mad Ad Vdaf FCdaf Cdaf Hdaf Ndaf Sdaf O* (atomic ratio) HM 18.40 4.72 48.72 51.28 69.12 6.11 1.17 0.45 23.15 1.06 0.25 HM-Dem 12.20 0.31 46.98 53.02 67.45 6.53 0.99 0.30 24.73 1.16 0.27 
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表 2 两种铁矿石的成分分析
Table 2. Composition analysis of two kinds of iron ores
Sample Composition analysis of iron ores w/% TFe (total iron) Al2O3 SiO2 P CaO MgO CT 41.43 4.8 26.53 0.39 4.35 3.27 JT 33.77 2.24 24.21 0.24 1.90 2.49
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