复合固硫剂对型煤固硫的影响研究
Effect of compound sulfur retention agent on sulfur retention behaviors of coal briquettes
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摘要: 固硫型煤作为煤燃烧中脱硫的一种重要方法，在燃煤SO2的减排方面起着重要的作用。为了考察固硫剂和固硫添加剂对型煤固硫及其对型煤燃烧释放SO2的规律的影响，对利用氧化镁和氧化钙为固硫剂，以煤矸石和粉煤灰为固硫添加剂进行了研究，同时通过XRD和SEM表征，进一步探讨了固硫剂及添加剂的固硫作用和机理。研究结果表明：(1) CaO和MgO可与煤燃烧释放的SO2结合生成MgSO4和CaSO4，从而有效降低煤在低温段（200～600℃）的SO2释放量，然而，生成的MgSO4不稳定，在高于700℃时会发生还原分解而重新释放出SO2；（2）煤矸石中的SiO2和Al2O3可在型煤燃烧过程中形成物质Ca5 (SiO4)2 (SO4)，该物质热稳定性较高，抑制了硫酸钙的分解，从而提高了型煤的固硫率。Abstract: Clean coal briquette is one of the most effective techniques of sulfur fixing during coal burning， it plays an important role in reducing sulfur dioxide. In order to find out the sulfur retention and behaviors of sulfur retention agent and additive agent， the coal gangue and coal ash based on magnesia-and calcium-base sulfur retention agents were studied.Furthermore，sulfur retention mechanisms were discussed based on XRD and SEM characterizations.The results show that: (1)CaO and MgO can react with SO2 and turn into CaSO4 and MgSO4 at low temperatures(200~600℃). MgSO4， however， is easily decomposed at 700~900℃ and decrease the sulfur retention rates. (2)SiO2 and Al2O3 in coal gangue can react with CaSO4 into a more stable substance Ca5 (SiO4)2 (SO4) at high temperatures and thus restrain the decomposition of sulfate species.
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Key words:
- magnesia /
- calcium oxide /
- sulfur retention /
- coal briquette /
- sulfur retention additive agent
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