Influence of dolomite additive on the ash fusion and potassium fixation characteristics of rice straw
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摘要: 在管式炉中研究了稻草秸秆的结渣特性与白云石作为添加剂对稻秆燃烧结渣的影响及其机理。采用电感耦合等离子体发射光谱（ICP-OES）和X射线衍射（XRD）表征了稻秆灰分与白云石之间的相互作用。结果表明，当白云石添加质量分数为5%时，对稻秆的结渣特性具有明显的改善。白云石具有较好的固钾能力，在900和1000℃下尤为明显。白云石中富含的Mg和Ca元素能够与稻秆灰分中的SiO2反应形成高熔点的硅酸盐矿物，包括透辉石、钙镁橄榄石和镁硅钙石。Abstract: The influence of dolomite as an additive on the slagging and potassium fixation characteristics of rice straw upon burning was investigated in a tube furnace; the slagging mechanism as well as the interaction between the rice straw ash and dolomite were explored by using the inductively coupled plasma optical emission spectrometry (ICP-OES) and X-ray diffraction (XRD). The results show that the slagging characteristics of rice straw are significantly influenced by adding 5% dolomite. Dolomite can greatly improve the potassium fixation ability, especially at 900-1000℃; moreover, the Mg and Ca elements rich in dolomite can react with SiO2 in the rice straw ash, forming high-melting silicate minerals including diopside, monticellite and merwinite.
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Key words:
- rice straw /
- ash /
- slagging /
- dolomite /
- potassium fixation
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图 2 样品1-5的灰熔融温度
Figure 2 Fusion temperatures of various rice straw samples
sample 1: pure rice straw ash;
sample 2: rice straw ash with 2.5% dolomite;
sample 3: rice straw ash with 5% dolomite;
sample 4: rice straw ash with 7.5% dolomite;
sample 5: rice straw ash with 10% dolomite
图 3 不同样品的宏观相貌照片
Figure 3 Macro-morphologies of various ash samples burned at different temperatures
图 5 不同温度下的灰样成分
Figure 5 XRD patterns of ash samples deposited at different temperatures
(a): 600℃; (b): 700℃; (c): 800℃; (d): 900℃; (e): 1000℃
1: KCl; 2: MgO; 3: SiO2; 4: CaO; 5: CaSiO3; 6: CaAl2Si3O10; 7: Mg2SiO4; 8: CaAl2Si2O8; 9: KAlSi3O8; 10: CaMgSi2O6
图 6 不同温度下的稻秆灰中钾固定率
Figure 6 Potassium capture efficiency of various ash samples deposited at different temperatures
sample 1: pure rice straw ash;
sample 2: rice straw ash with 2.5% dolomite;
sample 3: rice straw ash with 5% dolomite;
sample 4: rice straw ash with 7.5% dolomite;
sample 5: rice straw ash with 10% dolomite表 1 稻草秸秆的工业分析与元素分析
Table 1 Proximate and ultimate analyses of rice straw
Sample Proximate analysis wad /% Ultimate analysis wd /% Qnet.ad/
(kJ·kg-1)M A V FC C H O N S Rice straw 6.57 10.52 72.42 10.49 44.65 6.93 35.75 0.89 0.34 15274.7 
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表 2 稻秆灰与白云石的成分分析
Table 2 Composition analysis of rice straw ash and dolomite
Samples SiO2 Al2O3 Fe2O3 Content w/% K2O Na2O CaO MgO SO3 Rice straw ash 29.66 2.66 1.16 10.80 7.25 1.06 32.18 2.34 Dolomite 2.13 0.23 0.15 29.08 19.27 1.45 0.13 0.23
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表 3 样品内部元素原子百分比
Table 3 Atomic percentages of various elements in the ash
Sample Content w/% O Na K Al Si Mg Ca S Cl 1 35.63 0.80 10.95 8.12 40.23 2.06 1.11 0.24 0.31 3 28.15 1.14 2.40 0.49 37.46 16.28 12.89 0.17 0.19
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表 4 不同温度下的样品成灰率
Table 4 Ash formation rates at different temperatures
Sample w/% 600℃ 700℃ 800℃ 900℃ 1000℃ Dolomite 95.84 68.76 66.11 53.43 52.31 Sample 1 15.82 13.44 11.45 11.40 10.86 Sample 2 16.51 16.45 15.87 16.19 16.27 Sample 3 17.16 15.96 15.10 15.40 15.35 Sample 4 17.97 15.05 13.94 15.01 14.72 Sample 5 18.80 14.00 13.33 14.80 14.62
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