Study on the influence of particle size on the ash melting behavior of Jincheng coal
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摘要: 探索山西晋城煤在灰熔聚流化床气化过程中的结渣机理。采用山西晋城无烟煤,将其破碎到不同粒径,采用XRF、XRD、AFT、SEM和FactSageTM研究了煤的灰分、煤灰化学组成、矿物组成和熔融性随煤样粒径变化规律。结果发现,对于破碎到6 mm以下的晋城煤样,不同粒径子样煤灰化学组成和熔融温度差异不大;对于粉磨到0.2 mm以下的晋城煤粉样品,不同粒径子样化学组成和矿物组成存在较大差异,其中,铁含量差异最明显。AFT和SEM结果都证明, < 45 μm粒径煤粉子样煤灰熔融温度明显高于其他三种样品。FactSageTM计算得到的液相量变化规律和AFT、SEM观察结果一致,说明煤灰熔融性随粒径变化是煤灰化学成分离析造成的,而SiO2-Al2O3-Fe2O3三元相图较好地解释了晋城煤煤灰熔融性随粒径变化机理。Abstract: The slagging mechanism of the Jincheng coal in the ash-agglomerate fluidized bed gasification was explored. A typical Jincheng coal sampled from Shanxi, China was prepared into different particle size and the XRF, XRD, AFT, SEM and FactSageTM were employed to study the influence of particle size on the ash content, chemical and mineral composition and ash fusibility. The results indicate that the ash chemical composition and AFTs vary little with size below 6 mm. For the pulverized samples below 0.2 mm, there are apparent differences in the chemical composition and mineral composition, especially in Fe2O3. Both AFT results and SEM observations show that the sample with particle size less than 45 μm has a significantly higher melting temperature than the other three samples. The slag contents calculated with FactSageTM are consistent with the AFT results and SEM observations, which indicates that the change of ash melting behavior with particle size results from the change in chemical composition. The ternary phase diagram of SiO2-Al2O3-Fe2O3 can be used successfully to explain the mechanism of the change of ash melting behavior with particle size for Jincheng coal.
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Key words:
- Jincheng coal /
- ash-agglomerate fluidized bed /
- ash fusion temperature /
- slagging
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表 1 晋城原煤的工业分析和元素分析
Table 1 Proximate analysis and ultimate analysis of Jincheng raw coal
Proximate analysis w/% Ultimate analysis w/% Mad Ad Vd FCd Cdaf Hdaf Ndaf Odaf* St, d 4.49 19.24 7.78 72.98 88.60 3.24 1.11 3.94 3.11 *:by difference 表 2 晋城原煤煤灰化学组成含量
Table 2 Chemical composition of Jincheng raw coal ash
Content w/% SiO2 Al2O3 CaO Fe2O3 MgO TiO2 P2O5 K2O Na2O SO3 47.50 33.05 3.07 8.39 1.12 1.17 0.06 0.96 0.18 2.20 表 3 晋城煤粉不同粒径煤灰化学组成
Table 3 Ash chemical composition of size fractions in pulverized Jincheng coal sample
d/μm Content w/% SiO2 Al2O3 CaO Fe2O3 MgO TiO2 P2O5 K2O Na2O SO3 <45 59.37 33.78 3.20 6.55 1.06 1.06 0.06 1.00 0.18 1.52 45-75 55.18 30.56 3.20 13.77 1.59 1.32 0.06 0.60 0.12 2.65 75-105 55.21 31.83 2.75 15.67 1.01 1.10 0.06 0.58 0.10 2.10 >105 55.29 33.58 2.16 13.00 1.05 1.16 0.06 0.65 0.09 1.50 -
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