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摘要: 在单流化床反应器上探究了污泥化学链燃烧过程中氮迁移转化特性。由于赤铁矿载氧体反应活性低，采用30%水泥对其改性。结果表明，水泥改性可提高污泥热解气化反应速率以及赤铁矿还原反应速率，进而提高污泥碳转化率，但是NO生成率也增加。随着反应温度的升高，污泥的碳转化率和NO生成率均增加。另外，随着水蒸气浓度的增加，碳转化率增加，同时可降低NO生成。在污泥化学链燃烧过程中，NO生成率为0.286%-0.768%，低于污泥空气焚烧氮氧化物排放量。Abstract: The experiments were conducted in a bench-scale fluidized-bed reactor. To improve the reactivity of hematite, cement was added. The results show that cement-modified hematite possessed a higher reactivity, leading to an increase in carbon conversion of sewage sludge. Nevertheless, the NO emission also increased as compared to hematite alone. The rise of fuel reactor temperature can intensify both carbon conversion and NO emission. Meanwhile, the rise of steam content can increase carbon conversion and decrease NO emission. Approximately 0.286%-0.768% of nitrogen measured was NO, which is lower than the value in sewage sludge air incineration process.
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Key words:
- sewage sludge /
- hematite /
- cement /
- chemical looping combustion /
- nitrogen transformation
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图 1 小型流化床反应器系统示意图
Figure 1 Schematic illustration of the bench-scale fluidized bed reactor
图 2 900 ℃时基于赤铁矿的污泥化学链燃烧过程中气体产物排放特性
Figure 2 Gas concentrations in CLC of sewage sludge at 900 ℃ with hematite as oxygen carrier
图 3 900 ℃时基于水泥-赤铁矿载氧体的污泥化学链燃烧过程中的气体产物排放特性
Figure 3 Gas concentrations in CLC of sewage sludge at 900 ℃ with cement-hematite as oxygen carrier
图 4 900 ℃下基于氧化钙-赤铁矿载氧体的污泥化学链燃烧过程中NO排放特性
Figure 4 NO conversion as a function of the CaO/ hematite mass ratio in CLC of sewage sludge at 900 ℃
图 5 反应温度对污泥化学链燃烧过程中碳转化率和NO生成率的影响
Figure 5 Carbon conversion and NO conversion in CLC of sewage sludge at different temperatures
图 6 水蒸气浓度对污泥化学链燃烧过程中碳转化率和NO生成率的影响
Figure 6 Carbon conversion and NO conversion in CLC of sewage sludge at different steam content in fluidizing gas
图 7 水泥-赤铁矿为载氧体时污泥化学链燃烧过程中碳转化率和NO生成率随循环次数的变化
Figure 7 Carbon conversion and NO conversion as a function of cycle numbers in CLC of sewage sludge with cement-hematite
图 8 多次循环反应后水泥-赤铁矿载氧体的SEM照片
Figure 8 SEM images of the cement-hematite fresh (a), after 1st cycle (b) and after 10th cycle (c) with sewage sludge
表 1 载氧体的化学成分分析
Table 1 Composition of the oxygen carriers
Sample Composition w /% Fe2O3 SiO2 Al2O3 CaO MgO SO3 others Hematite 83.21 7.06 5.13 0.24 1.90 0.21 2.01 Cement 1.52 9.16 54.76 28.9 3.20 0.46 2.00 Cement-hematite 54.73 6.96 22.54 11.01 1.82 0.28 2.66 
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表 2 污泥的工业分析和元素分析
Table 2 Proximate and ultimate analyses of the sewage sludge used
Proximate analysis wad /% Ultimate analysis wad /% QHV/
(MJ·kg-1)M V FC A C H N S O 4.89 35.88 3.37 55.86 21.55 3.82 3.76 0.55 9.57 10.31
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