Emission characteristics and control of NOx from oil sludge char fluidized bed combustion
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摘要: 为无害化处理油泥焦，采用小型流化床反应器，研究了不同温度、不同颗粒粒径下油泥焦的燃烧氮氧化物释放特性，并借助空气分级燃烧技术降低NOx排放。SEM电镜和物理吸附结果表明，油泥焦颗粒表面结构致密、孔道稀疏，不利于其内部有机质充分燃烧。燃烧实验结果表明，油泥焦燃烧产生的NOx主要来源于焦炭氮，来自挥发性氮的较少。适当降低燃烧温度、减小颗粒粒径既能保证油泥焦充分燃烧，又能抑制氮氧化物排放。实施空气分级燃烧时，通过优化过量空气系数、二次风比例和二次风入口位置，能够获得显著的NOx减排效果，同时可以有效抑制飞灰产生，有助于烟气终极处理。Abstract: To realize innocent treatment of oil sludge char, a lab-scale fluidized bed reactor was employed to study combustion of the oil sludge char in the term of nitrogen oxide emission characteristics at various different temperatures and particle sizes, as well as the reduction in the emission of NOx by using air-staging combustion technology. According to the results of scanning electron microscope and physical adsorption analyses of oil sludge char, the surface structure of the sludge char is dense and its pores are sparse, which is not conducive to the full combustion of organic matter inside. The combustion experiments of oil sludge char show that the generated NOx is mainly from coke-N and less from volatile-N. Reduction in the combustion temperature and the particle size to a proper extent can not only ensure full combustion of oil sludge char, but also inhibit NOx emission. When conducting air-staging combustion, by optimizing the excess air ratio, proportion of secondary air and position of secondary air inlet, the NOx emission is considerably reduced, and meanwhile the generation of fly ash is restrained, and these are beneficial for the ultimate treatment of the flue gas.
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Key words:
- oil sludge char /
- fluidized bed /
- combustion /
- NOx emission /
- air-staging combustion
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图 1 流化床燃烧实验装置流程示意图
Figure 1 Flowchart of the fluidized bed combustion experiment device
图 2 油泥焦燃烧过程中NOx排放质量浓度随时间的变化
Figure 2 Concentration variation of NOx emission with time on line during the oil sludge char combustion
图 3 不同温度下NOx排放质量浓度和N转化率的变化
Figure 3 Variation of NOx emission and N conversion at different combustion temperatures
图 4 不同粒径的油泥焦燃烧的NOx质量浓度和N转化率
Figure 4 Concentration of NOx emission and conversion of N during combustion the oil sludge char with different particle sizes
图 6 不同二次风比例条件下的NOx排放和N转化率变化
Figure 6 Variation of NOx emission and N conversion with different proportion of secondary air
图 7 不同ER和二次风位置条件下的NOx排放和N转化率变化
Figure 7 Variation of NOx emission and N conversion with different ER and secondary air locations
(a): particle size: 0.45-0.5 mm; temperatures: 900℃; —■—: 1.1; —●—: 1.3; —▲—: 1.5; : 1.7 (b): : NOx concentration of A; : NOx concentration of B; : NOx concentration of C; —□—: fuel-N conversion of A; —○—: fuel-N conversion of B; —△—: fuel-N conversion of C
图 8 无二次风时各ER条件下的CO排放质量浓度
Figure 8 CO emission concentration at different ER with not secondary air
图 9 不同ER和二次风位置条件下的飞灰量
Figure 9 Fly ash amount at different ER and secondary air locations
表 1 油泥焦的工业分析和元素分析
Table 1 Proximate and ultimate analyses of the oil sludge char
Proximate analysis war/% Ultimate analysis wd/% QHHV
/(MJ·kg-1)M V A FC* N C H S O* 2.37 4.52 75.64 17.47 0.53 16.29 0.48 0.35 4.87 5.31 ar: as received basis; d: dry basis;*: calculated by difference 
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表 2 油泥焦灰的熔融特性
Table 2 Melting properties of the oil sludge char ash
Initiator DT ST HT FT Temperature t/℃ 1100 1150 1180 1420
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表 3 油泥焦灰的XRF分析
Table 3 XRF analysis of the oil sludge char ash
Component Na2O MgO Al2O3 SiO2 P2O5 SO3 K2O CaO TiO2 MnO Fe2O3 Others Percent w/% 2.07 2.49 13.70 60.73 0.62 2.04 2.79 8.22 0.75 0.14 5.98 0.47
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表 4 油泥焦原料的BET分析
Table 4 BET analysis of the raw materials of the oil sludge char
Parameter Value Surface area A/(m2·g-1) 12.344 Pore volume v/(cm3·g-1) 0.034 Pore size d/nm 10.992
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