Effects of syngas from semi-coke in-situ gasification on yield and quality of tar from pyrolysis of Naomaohu coal
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摘要: 本研究采用实验室自制的热解气化一体化反应器,考察了气化合成气对煤热解焦油产率和品质的影响。结果表明,淖毛湖煤热解焦油产率在600 ℃时达到最大,气化合成气对提高低温(550–600 ℃)煤焦油的产率更有利,其中,550 ℃时焦油产率较N2下提高了4.4%。气化合成气气氛下,高温(650–800 ℃)焦油的产率较N2低,但650–700 ℃热解焦油的品质明显改善,其中,轻质组分的产率有明显提升;低于600 ℃热解挥发分中脂肪烃和含氧化合物的裂解反应加剧,使焦油中其含量降低,而苯系和萘系化合物的生成量增加;650 ℃以上的热解挥发分中酚类化合物的二次裂解反应会加剧,导致焦油中其生成量降低;对800 ℃热解挥发分中多环芳烃二次裂解反应的发生更有利,但对提高低于700°热解焦油中多环芳烃的生成量则更加有利。Abstract: Pyrolysis atmosphere has significant effect on yield and composition of coal tar. A pyrolysis and gasification integrated reactor in laboratory was used to investigate effects of gasification syngas on yield and composition of coal tar. The results show that tar yield of Naomaohu coal reaches the maximum at 600 ℃, and gasification syngas (G-gas) is more beneficial to improve the tar yield at low temperature (550–600 ℃). Especially, 550 ℃ tar yield increases by 4.4% compared with that under N2. With the introduction of G-gas, the yield of tar obtained at high temperature (650–800 ℃) decreases, but the quality of tar obtained at 650–700 ℃ is improved obviously due to the increase of light components. The cracking reaction of aliphatic hydrocarbons and oxygen-containing compounds in volatiles from pyrolysis at 550 and 600 ℃ is intensified by G-gas, thus substituted benzene and naphthalene compounds in coal tar increase. For the volatiles obtained above 650 ℃, the secondary cracking reaction of phenolic compounds is enhanced with the introduction of G-gas, which results in a decrease of phenolic compounds in tar. G-gas is also favorable for the secondary cracking reaction of polycyclic aromatic hydrocarbons in volatiles from pyrolysis at 800 ℃, but more favorable for generation of which in the tar obtained below 700 ℃.
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Key words:
- Naomaohu coal /
- gasification gas /
- pyrolysis /
- coal tar /
- tar quality
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图 1 实验装置示意图[25]
1-feeder; 2-reactor; 3-fumace; 4-mass flow controller; 5-water tank; 6-pump; 7-steam generator; 8-condenser; 9-constant temperature circulator; 10-ice-water trap; 11-dry ice trap; 12-THF trap; 13-cotton filter; 14-wet gas flowmeter; 15- high molecular cellulose filter; 16-desiccant; 17-raman laser gas analyzer
Figure 1 Schematic diagram of experimental equipment [25]
Proximate analysis w/% Ultimate analysis wdaf/% Gray-King wdaf/% Mar Ad Vdaf C H N S Oa tar yield 19.5 5.8 50.12 74.35 5.13 0.72 0.31 19.49 15.4 ar: as received basis, d: dry basis, daf: dry and ash free basis, a: by difference 表 2 淖毛湖煤碳结构类型及含量[28]
Table 2 Proportion of different structural carbons in solid-state 13C NMR spectra[28]
Symbol Chemical shift Carbon type Proportion of different carbon types in coal ${f}_{{\rm{al}}}^{1}$ 0−25 methyl 0.11 ${f}_{{\rm{al}}}^{2}$ 25−50 methylene 0.19 ${f}_{ {\rm{al} } }^{{\rm{o1}}}$ 50−67 methoxy 0.21 ${f}_{ {\rm{al} } }^{{\rm{o2}}}$ 67−90 oxy-methine, saccharide, alcohol, ether 0.05 ${f}_{{\rm{a}}}^{1}$ 90−129 aromatic atoms bound to hydrogen 0.19 ${f}_{{\rm{a}}}^{2}$ 129−137 bridging ring junction
aromatic carbon0.10 ${f}_{{\rm{a}}}^{3}$ 137−148 branched aromatic carbon 0.07 ${f}_{ {\rm{a} } }^{{\rm{o1}}}$ 148−171 oxy-aromatic carbon 0.03 ${f}^{{\rm{co}}}$ 171−187 carboxyl, ester, quinone 0.01 ${f}^{{\rm{co}}}$ 187−220 ketone, quinine, aldehyde 0.04 -
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