Release and transformation of sodium in an opposed multi-burner coal-water slurry gasifier
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摘要: 基于多喷嘴对置式水煤浆气化热态实验平台，开展气化炉内钠元素的释放与转化特性研究。对收集的气化炉内轴向不同位置处颗粒物样品进行分析，利用微波消解和化学分级洗对颗粒物进行预处理，借助原子火焰吸收光谱仪（FASS）定量测定颗粒物中钠元素含量，并采用扫描电镜-能谱仪联用系统（SEM-EDS）表征颗粒物的表观形态及其表面元素组成。FAAS测定结果表明，钠元素释放率随距离喷嘴平面间距的增加呈先增加再减少的趋势，喷嘴平面附近为钠元素主要释放区域。随着炉内反应的进行，钠元素由水溶态、离子交换态向酸溶态和残渣态转变。结合SEM-EDS结果可知，炉内反应过程中，矿物质熔融形成球形颗粒物，与气相中的钠反应生成硅酸盐和硅铝酸盐，且钠元素含量随球形颗粒物的增多而增加。Abstract: Based on the bench-scale opposed multi-burner (OMB) coal-water slurry gasification experimental platform, the transformation and release characteristics of sodium during the reaction of coal in the gasifier were studied. Particles sampled at different axial distances from burner plane to top and bottom along the gasifier chamber were analyzed. After the microwave digestion and chemical fractionation analysis, the content of sodium was tested by flame atomic absorption spectrometer (FASS). The morphololgy and elements of particles were analyzed by scanning electron microscopy and energy spectrum application system (SEM-EDS). The FASS results showed that the release rate of sodium increased first then decreased with increasing distance to the burner plane. The area near the burner plane was the major release area of sodium. With the reaction in progress in the gasifier the occurrence form of sodium was transformed from water-soluble sodium and ion-exchangeable sodium into the acid-soluble sodium and residual sodium. Combining the SEM-EDS and FASS results, the spherical particles which were formed through melt minerals reacted with sodium in the gas phase to form silicate and sialic acid salt in gasifier. The increasing number of spherical particles led to an increase in the sodium content in the particles.
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Key words:
- opposed multi-burner (OMB) gasifier /
- particles /
- sodium /
- release /
- occurrence form
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图 1 多喷嘴对置式水煤浆气化实验装置示意图
Figure 1 Schematic diagram of bench-scale OMB entrained-flow gasifier
1: Ar tank; 2: O2 tank; 3: evaporator; 4: diesel tank; 5: gear pump; 6: coal-water slurry tank; 7: screw pump; 8: burner 3# and burner 4#; 9: camera; 10: computer
图 9 颗粒物的电镜照片
Figure 9 Electron microscopy photos of particles
(a): PM3#; (b): PM0#; (c): PM7#; (d): the broken skeleton particles
表 1 煤样的工业分析和元素分析
Table 1 Proximate and ultimate analyses of coal
Proximate analysis wad/% Ultimate analysis wad/% M A V FC C H O N S 1.38 10.59 32.19 55.84 71.8 4.61 11.07 1.17 0.75 
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表 2 煤样的灰分组成
Table 2 Chemical composition of coal ash
Composition w/% SiO2 Al2O3 Fe2O3 Na2O CaO SO3 TiO2 MgO K2O P2O5 others 49.01 32.48 5.31 3.97 3.64 2.03 1.23 0.73 0.72 0.63 0.25
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表 3 颗粒物中不同赋存形态钠的含量
Table 3 Sodium content of different occurrence forms in coal
H2O NH4AC HCl Residue Total Content w/ (mg·g-1) 2.48 0.55 0.31 0.86 4.20 Percent w/% 59.04 13.09 7.32 20.50 100.00
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表 4 不同区域元素的组成
Table 4 Element distribution in different area
Content w/% C O Na Mg Al Si S Fe Ca others a-1 35.66 44.25 2.62 0.81 7.06 7.76 0.15 0.35 0.81 0.53 a-2 72.79 22.29 1.35 0.31 1.49 1.24 0.18 0.06 0.06 0.61 a-3 64.35 32.56 0.82 0.06 0.18 0.15 0.37 0.46 0.16 0.89 b-1 31.59 46.47 3.54 0.77 9.23 6.53 0.22 0.43 0.48 0.75 b-2 79.23 16.11 0.81 0.20 1.35 1.33 0.54 0.04 0.05 0.34 b-3 83.74 13.22 0.66 0.16 0.47 1.14 0.32 0.02 0.01 0.26 c-1 29.13 49.02 3.96 0.85 7.93 7.50 0.17 0.27 0.56 0.60 c-2 77.04 15.29 0.84 0.14 3.32 2.66 0.28 0.02 0.02 0.40 c-3 83.40 13.98 0.81 0.18 0.58 0.54 0.16 0.04 0.03 0.27 d-1 19.62 60.75 4.79 0.56 10.62 3.07 0.17 0.27 0.12 0.03 d-2 36.98 2.75 0.00 0.01 14.93 23.73 0.36 8.70 8.40 4.15
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