Study on the oxy-fuel co-combustion of coal gangue and semicoke and the pollutants emission characteristics
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摘要: 利用热重分析仪和管式炉实验,研究了煤矸石与半焦的富氧混烧特性,考察了半焦混烧比例、O2含量和反应温度对燃烧特性和污染物排放特性的影响。结果表明,混烧半焦和提高O2含量均可显著改善混合燃料的燃烧性能,当半焦混烧比例为75%时,着火和燃尽指数最高。随半焦混烧比例增大,CO和SO2转化率均逐渐降低。提高反应温度,CO转化率降低,SO2转化率增大,NO转化率呈现先升高然后降低或缓慢增加趋势。反应温度为900 ℃时,混烧半焦可降低燃烧过程的NO排放量。其余反应温度下,混烧半焦会增大NO转化率。随O2含量升高,混合燃料富氧燃烧过程的CO转化率降低,NO转化率升高,SO2峰值释放量和转化率呈先降低后升高的趋势。当O2体积分数为20%时,SO2转化率最低。Abstract: The oxy-fuel co-combustion of coal gangue and semicoke and the pollutants emission characteristics were studied by thermogravimetric analyzer and tube furnace experiments. The effects of semicoke blending ratios, O2 concentration and temperature were investigated. The results showed that the combustion performance of blended fuel could be improved with the addition of semicoke and the increase of O2 concentration. The maximum ignition and burnout index were obtained when semicoke blending ratio was 75%. The xCO and
${x_{{\rm{S}}{{\rm{O}}_{\rm{2}}}}} $ gradually decreased with the increase of semicoke blending ratios. As the increase of temperature, the xCO decreased,${x_{{\rm{S}}{{\rm{O}}_{\rm{2}}}}} $ increased while xNO firstly increased then decreased or slowly grew. The NO emission could be reduced with the addition of semicoke when the temperature was 900 ℃. However, it would aggravate NO emission at other temperatures. With the increase of O2 concentration, the xCO decreased, xNO increased while${x_{{\rm{S}}{{\rm{O}}_{\rm{2}}}}} $ firstly decreased and then increased. The minimum${x_{{\rm{S}}{{\rm{O}}_{\rm{2}}}}} $ was obtained when O2 concentration was 20%. -
表 1 样品的元素分析、工业分析和热值
Table 1 Proximate, ultimate and heating value analyses of samples
Sample Proximate analysis war/% Ultimate analysis war/% LHV/(MJ·kg−1) M V A FC* C H N S O* Coal gangue 1.52 22.90 52.25 23.33 40.67 2.22 0.61 1.50 1.23 14.73 Semicoke 8.55 8.11 10.05 73.29 73.81 1.32 0.88 0.39 5.00 23.18 note: M-moisture; V-volatile; A-ash; FC-fixed carbon; LHV-lower heating value, ar-received basis, *: by difference 表 2 不同半焦混烧比例下混合燃料的燃烧特征参数
Table 2 Combustion characteristic parameters at different semicoke blending ratios (O2 concentration is 30%)
Semicoke
blending
ratios/%t/℃ Di × 10−3
/min−3Df × 10−4
/min−3S × 10−8
/(min−2·℃−3)ti tm tf 0 433 493 668 1.97 1.57 4.07 25 433 493 657 2.04 1.77 5.23 50 469 515 858 3.52 2.36 5.63 75 469 515 858 3.87 2.59 7.45 100 474 534 858 3.44 1.87 8.23 表 3 不同O2体积分数下混合燃料的燃烧特征参数
Table 3 Combustion characteristic parameters at different O2 concentrations (semicoke blending ratio is 50%)
O2 concentration/% ti/℃ tm/℃ tf/℃ Di × 10−3/min−3 Df × 10−4/min−3 S × 10−8/(min−2·℃−3) 10 478 613 702 1.26 0.46 5.21 20 468 563 692 1.98 1.06 7.71 30 469 515 858 3.52 2.36 5.63 40 464 524 667 4.14 6.30 14.93 -
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