Mechanism analysis of synergy behavior during blended char co-gasification of bituminous coal and rice straw
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摘要: 基于热重分析仪考察了神府烟煤焦、稻草焦和神府烟煤-稻草混合焦样气化反应活性及共气化过程协同行为。并借助电感耦合等离子体发射光谱仪和扫描电子显微镜-能谱仪联用装置探讨了共气化过程活性矿物组分的迁移转化特性，以关联解释共气化协同行为演变。结果表明，与煤焦单独气化相比，稻草焦掺混有利于提高煤焦整体气化反应活性。混合焦样共气化过程协同行为随碳转化率的提高呈先逐渐减弱的抑制作用，达到某一碳转化率（记为转折碳转化率）后呈不断增强的协同促进作用，且转折碳转化率随气化温度升高而提高。神府烟煤-稻草混合焦样共气化过程协同行为演变主要归因于共气化过程活性K和Ca转化特性的共同影响。神府烟煤-稻草混合焦样共气化整体协同行为呈协同促进作用，并随气化温度的升高而减弱。Abstract: The gasification reactivity of Shenfu bituminous coal char, rice straw char and their blended char and the synergy behavior in blend were studied using TGA. Additionally, inductively coupled plasma emission spectrometer and scanning electron microscopy coupled with energy disperse spectroscopy were employed to explore the active AAEM transformation characteristics in co-gasification process, so as to correlate and explain the synergy behavior variations during co-gasification. The results show that the addition of rice straw char to coal char was favorable for promoting the overall char gasification reactivity compared with individual coal char gasification. The synergy behavior at different co-gasification conversions changes from the gradually decreasing inhibition effect at the early stage of co-gasification to the gradually enhanced synergistic effect when reaching a turning conversion that is increased at higher gasification temperature. The synergy behavior variations during blended char co-gasification are attributed to the combined effect of active K and Ca transformation characteristics in co-gasification process. Furthermore, the overall synergy behavior of blended char co-gasification is shown as a positive synergistic effect, and it is weakened with the increase of gasification temperature.
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Key words:
- coal /
- biomass /
- co-gasification /
- synergy behavior /
- mechanism
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图 1 自由下落式快速热解装置示意图
Figure 1 Schematic diagram of free-fall rapid pyrolysis reactor
1: N2 cylinder; 2: temperature controlling system; 3: fixed bed reactor; 4: sample basket; 5: condensing unit; 6: washing unit; 7: filter unit; 8: cumulative flow meter; 9: water-cooling jacket
图 2 气化反应活性曲线
Figure 2 Gasification reactivity curves of RS-800P (a), SF-800P (b) and SF:RS-1:1-800P (c)
(800-gasification at 800 ℃, cal-calculated gasification reactivity curve)
图 3 混合焦样共气化过程协同因子变化
Figure 3 Synergy index variations during blended char co-gasification
图 4 共气化过程不同转化率的活性AAEM相对转化率
Figure 4 Relative transformation ratio of active AAEM at different co-gasification conversions
图 5 焦样及气化半焦的电镜照片
Figure 5 SEM photos of chars and gasification semi-chars
(SF:RS-1:1-800P-50%-SF represents SF particles in semi-char (conversion, 50%) of SF:RS-1:1-800P gasified at 900 ℃)
表 1 样品的工业分析、元素分析和灰熔融温度
Table 1 Proximate analysis, ultimate analysis and ash fusion temperature of tested samples
Sample Proximate analysis wd/% Ultimate analysis wd /% Ash fusion temperature t/℃ V FC A C H N O S DT ST HT FT SF 35.42 58.29 6.29 79.14 2.32 1.12 10.36 0.77 1152 1167 1175 1179 RS 75.05 15.35 9.60 44.08 6.24 1.13 38.57 0.38 1198 1257 1290 1380 
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表 2 样品的灰组成
Table 2 Ash composition of tested samples
Sample Ash composition w/% SiO2 Al2O3 K2O Na2O CaO Fe2O3 MgO SF 33.36 12.44 0.67 1.73 27.78 9.11 1.34 RS 58.88 0.18 21.97 1.13 4.20 0.26 2.73
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表 3 焦样气化反应活性指数
Table 3 Gasification reactivity index of char samples
Sample R0.9/min-1 800 ℃ 850 ℃ 900 ℃ 950 ℃ SF-800P 0.003 0.011 0.030 0.067 RS-800P 0.008 0.022 0.052 0.115 SF:RS-1:1-800P 0.006 0.019 0.044 0.087
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表 4 焦样及混合焦样气化半焦中活性AAEM含量
Table 4 Active AAEM content in chars and gasification semi-chars of blended char
Sample Element content /(mg·g-1) (raw char/blended char) active K-exp active K-cal active Ca-exp active Ca-cal RS-800P 38.80 - 6.36 - SF-800P 0.12 - 35.38 - SF:RS-1:1-800P 11.72 - 26.67 - SF:RS-1:1-800P-10% 7.84 10.72 12.61 14.71 SF:RS-1:1-800P-30% 7.46 7.70 12.22 14.30 SF:RS-1:1-800P-50% 6.42 1.84 12.01 14.08 SF:RS-1:1-800P-70% 4.19 0.76 11.66 13.86 SF:RS-1:1-800P-90% 1.75 0.31 10.96 13.50 note: SF:RS-1:1-800P-x% represents semi-char (conversion, x%) of SF:RS-1:1-800P
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表 5 神府煤焦及混合焦样气化半焦中神府煤焦颗粒表面元素组成
Table 5 Elemental composition of the particle surface of SF-800P and SF gasification semi-char of SF:RS-1:1-800P
Sample Elemental composition /% C O Si K K/Si RS-800P-epidermis 19.50 44.29 33.21 0.78 0.02 RS-800P-ground tissue 88.81 8.53 0.36 1.04 2.89 SF-800P 86.38 6.57 0.26 0.09 0.35 SF:RS-1:1-800P-50%-SF 78.49 11.64 0.46 0.83 1.80
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