神府烟煤以及贵阳贫煤分别与木屑掺烧灰沉积特性研究

Ash deposition characteristics during co-combustion of coal and sawdust

利用CCD相机和沉积探针组成的在线监测系统,在50 kW下行炉上研究了木屑与神府烟煤以及贵阳贫煤的掺烧灰沉积特性。灰渣沉积过程可分为三个阶段:缓慢增长阶段、快速增长阶段和稳定阶段。烟煤掺烧灰沉积厚度随着木屑掺烧比例的增加而增加,贫煤掺烧灰沉积厚度则随着木屑掺烧比例增加而减小。烟煤中掺烧木屑比例为0、6.7%、15%和22%时,渣层稳定厚度分别为1.37、3.85、11.50、20.56 mm,稳定相对热流密度分别为0.44、0.41、0.30、0.26。贫煤掺烧木屑比例为6.7%、15%和22%时,稳定厚度分别为18.65、10.97和9.78 mm,稳定相对热流密度分别为0.29、0.31、0.33。掺烧木屑之后,灰渣初始层中Ca、K元素显著增加。在相同温度下,随着木屑掺烧比例的增加,灰中熔融相比例增加,因为木屑灰分中含有较多的Na 2O、K 2O等碱金属氧化物,而Al 2O 3、SiO 2等含量较少,降低了灰的熔融温度。

The ash deposition characteristics during co-combustion of coal and sawdust was studied in a 50 kW furnace with an online monitoring system composed of CCD camera and ash deposition probe.The deposition process can be divided into three stages:slow growth stage,rapid and stable stage.The stable thickness of bituminous coal increases with increasing proportion of sawdust,while that of lean coal is opposite.The stable thickness of bituminous coal are 1.37,3.85,11.50,20.56 mm and the stable relative heat flux are 0.44,0.41,0.30,0.26 when blending ratio of sawdust are 0,6.7%,15%,22%respectively.The stable slags thickness of lean coal are 18.65,10.97,9.78 mm and the stable relative heat flux densities are 0.29,0.31,0.33 when blending ratio of sawdust are 6.7%,15%and 22%.Ca and K in the initial layer of deposition significantly increases in the co-combustion.The melting fraction calculated by FactSage software shows that at the same tem-perature,the melting fraction of ash increases as the sawdust is increased.Because the wood ash contains more alkali metal oxides such as Na 2O and K 2O,while the content of Al 2O 3 and SiO 2 is less,which lowers the melting temperature of ash.