五彩湾煤在/燃烧条件下的积灰特性 /

锅炉燃用准东煤极易发生严重的受热面积灰结渣等问题,制约了新疆准东地区煤炭资源的大规模利用。在一维沉降炉燃烧与积灰试验系统上,研究了准东五彩湾煤的积灰特性,分析了稀释气体种类、O2/CO2燃烧中氧浓度对飞灰沉积的影响。结果表明:在21%氧浓度下,与稀释气体为N2相比,稀释气体为CO2时得到的沉积灰颗粒之间黏连现象不明显,积灰倾向较弱; O2/CO2燃烧条件下,随着氧浓度提高,五彩湾煤的积灰倾向加重,细散灰颗粒减少,球形灰颗粒比例增加,灰颗粒的黏连现象加重。SEM-EDS分析结果表明:O2/CO2燃烧中随氧浓度的提高,沉积灰中的块状灰颗粒表面缩孔及凹坑增多,且灰颗粒表面黏附了白色细散絮状灰,Na和Cl的富集加重,这是造成高氧浓度燃烧受热面积灰加剧的重要原因;稀释气体种类对五彩湾煤积灰倾向的影响研究中,稀释气体为N2(空气燃烧)时,Na和Cl含量明显高于稀释气体为CO2(O2/CO2燃烧)时的含量。此外,燃烧稀释气体为N2的沉积灰中还出现了Ca和S元素的富集,高温下CaO与硅铝酸盐发生反应生成低温共熔体,这也是空气燃烧时积灰较O2/CO2燃烧严重的重要原因。XRD分析结果在一定程度上佐证了EDS的分析结论,灰分中CaSO4、NaCl等低熔点物质的富集导致了空气燃烧工况和O2/CO2高氧浓度燃烧工况积灰的加剧。燃烧的颗粒温度差异是导致O2/CO2燃烧和空气燃烧积灰特性不同的主要原因,也是造成不同氧浓度下O2/CO2燃烧积灰特性差异的主要原因。煤燃烧的颗粒温度较高时,煤粉着火、燃烧性能得到改善,更高的颗粒温度会导致烟气中出现更多的熔融灰,灰颗粒表面出现熔融相进而增强了灰表面的黏性,加剧积灰现象。 The boiler burning with Zhundong coal is prone to deposition and slagging problems on heat-exchanger surfaces,which severely restricts the wide utilization of coal resources in the Zhundong area of Xinjiang province.In this paper,the ash deposition characteristics of Wucaiwan coal were studied on the one-dimensional settling furnace combustion and ash accumulation test system,and the effects of dilution gas type and oxygen concentration of O2/CO2 combustion on fly ash deposition were analyzed.The results show that at the concentration of 21% oxygen,compared with N2,when the diluent gas is CO2,the adhesion phenomenon of the ash deposition is not obvious,and the tendency of ash accumulation is weak.Under combustion condition of O2/CO2,with the rise of oxygen concentration,the ash deposition of Wucaiwan coal tends to increase and the fine ash particles gradually decrease,the proportion of spherical ash particles gradually increases,and the adhesion phenomenon of ash particles gradually increases.The results of SEM-EDS analysis illustrate that with the increase of oxygen concentration in O2/CO2 combustion,the surface shrinkage and pits of the ash particles in the deposited ash gradually increase,the white fine floc ash adheres to the surface of the ash particles,and the enrichment of Na and Cl is gradually aggravated,which is an important reason for the intensification of ash deposition on the heating surface in the combustion with high oxygen concentration.In the influence research of dilution gas species on the ash deposition tendency of Wucaiwan coal，the element contents of Na and Cl are obviously higher when the diluent gas is N2 (air combustion) than when the diluent gas is CO2 (O2/CO2 combustion).In addition,the enrichment of Ca and S elements also occurs in the deposited ash when the combustion diluent gas is N2.At high temperature condition,CaO reacts with