Upgrading of Zhaotong coal by pyrolysis and its effect on the gasification reactivity
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摘要: 为了对储量相对丰富的昭通褐煤进行合理有效的分级转化利用，采用固定床程序升温热解的方法研究了不同温度下煤的热解行为，借助GC-MS和拉曼光谱对所得焦油和煤焦进行了表征分析，并在850℃下对不同热解温度制得的煤焦进行了水蒸气等温气化特性评价。结果表明，热解温度为700℃时，热解气体有效组分（H2、CO、CH4）的累积物质的量占总释放量的70%，此温度下热解气低位热值增长速率最快（以500℃下热解气低位热值为基准计算，其值为90%）；酚类化合物在500-700℃大量生成析出，而温度高于700℃时，酚类化合物的分解反应加剧。不同热解温度下所制煤焦的表观气化反应速率随热解温度的升高不断降低，气化产物中CO2与CO的物质的量逐渐升高，700℃热解制得的煤焦在水蒸气气氛下气化所得合成气中有效组分H2与CO的比率最高。Abstract: In order to integratedly utilize the relatively rich coal resource of Zhaotong mine, temperature-programmed pyrolysis experiments of Zhaotong lignite were performed in fixed bed reactor at different temperatures. The resultant coal tar and char were characterized by GC-MS and Raman Spectroscopy, respectively. Char-H2O isothermal gasification characteristics were evaluated in fixed bed reactor at 850℃. The results show that in pyrolysis at 700℃ the cumulative content of H2, CO and CH4 in gases accounts for about 70%, and the growth rate of low calorific value of gas is the fastest, which is 90% based on the value at 500℃. A large number of phenolic compounds are generated at 500-700℃. Above 700℃ the decomposition reactions of the phenolic compounds is intensified. With the increase of pyrolysis temperatures, the apparent reaction rate of char decreases, while the molar ratio of CO2 and CO increases. The molar ratio of H2 and CO in gasification from char pyrolyzed at 700℃ was the highest.
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Key words:
- pyrolysis upgrading /
- release of gas /
- coal tar /
- gasification reactivity
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图 1 热解温度为900 ℃下煤焦拉曼光谱的分峰拟合图
Figure 1 Curve-fitting of Raman spectrum of char obtained from pyrolysis at 900 ℃
图 3 昭通褐煤热解过程中气体产物瞬时释放曲线
■: CO; ●: H2; □: CO2; ∇: CH4; ◀: C2H6; ▷: C3H8
Figure 3 Change of gases releasing concentration during coal pyrolysis with temperatures
图 4 不同热解温度下褐煤焦拉曼谱图中I(Gr+Vl+Vr)/ID比值及总峰面积
Figure 4 I(Gr+Vl+Vr)/ID ratio and integral area of Raman spectrum of chars at different pyrolysis temperatures
图 5 昭通褐煤热解气组成、LHV随温度的变化
■: CO; ●: H2; △: CO2; ▼: CH4; ◀: C2H6; ▷: C3H8
Figure 5 Changes of gases composition and LHV during coal pyrolysis with temperatures
图 6 热解温度对酚类物质生成的影响
: phenol; : p/o/m-cresol; : o-metoxyphenol; : xylenol; : ethyphenol; : catechol; : 2-methoxy-4-ethyphenol; : methylnaphthol
Figure 6 Effect of pyrolysis temperature on the formation of phenolic compounds
图 7 热解温度对BTEXN各组分生成的影响
: benzene; : toluene; : ethybenzene; : p/o-xylene; : dimethylnaphthalene
Figure 7 Effect of pyrolysis temperature on the formation of BTEXN
图 8 不同热解终温下煤焦的表观反应速率随碳转化率的变化
■: 500 ℃; ●: 600 ℃; △: 700 ℃; ∇: 800 ℃; ◀: 900 ℃; ▷: 1 000 ℃
Figure 8 Specific reaction rate of char at different pyrolysis temperatures VS carbon conversion
图 9 水蒸气气氛下不同煤焦等温气化过程中气体释放量的比较
: CO; : CO2; : H2
Figure 9 Comparison of gas release amounts of various chars during isothermal gasification in steam
表 1 实验用煤的工业分析和元素分析
Table 1 Proximate and ultimate analyses of sample used in experiment
Proximate analysis w/% Ultimate analysis wdaf /% Mad Ad Vdaf C H N St O* 7.46 15.72 55.04 66.88 5.12 1.57 0.83 25.60 *: by difference 
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表 2 实验用煤的灰成分分析
Table 2 Analyses of ash composition in coal sample used in experiment
Content w/% SiO2 Al2O3 Fe2O3 CaO MgO TiO2 SO3 K2O Na2O P2O5 38.13 24.84 7.17 12.77 2.06 2.50 10.71 0.85 0.83 0.18
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