航天炉高硅铝烟煤煤灰熔融及黏温特性调控研究

Study on ash fusion and viscosity temperature characteristics adjustment of high silicon-aluminum coals on HT-L gasifier

具有高灰分、高硅铝、低硅铝比(质量比)煤灰特性的动力烟煤在气流床气化炉上鲜有应用,其煤质特性偏离气化用煤指标,且调控难度非常大。为将具有上述煤灰特性的动力烟煤应用于航天炉气化,开展煤质特性调控研究,利用灰熔融测试仪、高温旋转黏度仪以及热力学计算软件FactSage,研究了动力烟煤(HS)添加不同质量比的工业助熔剂(石灰石、铁矿石和二者复合助剂)以及配煤(白石湖煤)对煤灰熔融特性、黏温特性以及矿物质组成的影响。结果表明:HS灰硅铝比为1.32,酸碱比为12.82。热转化过程中煤灰矿物组成以莫来石为主要成分,是其四个灰熔融特征温度均高于1500℃的根本原因,黏温特性的调控难度大于一般晋城无烟煤黏温特性的调控难度;同等比例下工业助熔剂按调控效果由大到小依次为铁钙复合助剂、铁矿石、石灰石;单一石灰石助熔剂对HS的调控效果不佳,针对此类煤灰特性,宜选用铁钙复合助剂或与高碱金属煤灰特性的煤混配以降低灰熔融温度,改善黏温特性,即同时增加煤灰中CaO和Fe_(2)O_(3)等碱金属含量,使其在矿物质热转化过程形成如钙铁辉石、易变辉石、透辉石、堇青石和霞石等低熔点矿物质或多元低温共熔物,从而降低体系熔融温度。

The power bituminous coal with high ash,high silicon-aluminum and low silicon-aluminum ratio(mass ratio)is rarely utilized on the entrained bed gasification.Its coal quality characteristics deviate from the coal index for gasification,and the adjustment is obviously more difficult.To apply the power bituminous coal with the above-mentioned ash characteristics on HT-L gasifier and provide the research on the adjustment of coal quality characteristics,the effects of adding different proportions of industrial fluxes(such as limestone,iron ore and their compound additive)and blending coal(BSH)to the sample coal(HS)on its ash melting characteristics,viscosity-temperature characteristics and mineral transformation were studied by using the ash-fusion point meter,high-temperature rotating viscometer and thermodynamic calculation software FactSage.The results show that HS coal ash has a low silicon-aluminum ratio(1.32)and a high acid-base balance index(12.82).In the mineral thermal transformation behavior of coal ash,it mainly generated mullite,which is the reason for the high ash fusion temperatures(tD,tD,tH and tF all above 1500℃).Compared with general Jincheng anthracite coal,it is more difficult to adjust HS coal.When adding the same proportion of industrial fluxes,the adjustment effect from the largest to the smallest is: iron-calcium compound additive, iron ore, limestone. The effect of using only limestone is inferior;For the adjustment of such coal ash characteristics, it is recommended to use iron-calcium multi-auxiliaries or blending with other types of coals rich in alkali metals to reduce the ash-fusion temperature and improve the viscosity-temperature char-acteristic. By increasing the content of alkali metal elements such as CaO and Fe_(2)O_(3) simultane-ously, minerals with low melting point characteristics such as clinopyroxene,orthopyroxene,di-opside, cordierite,nepheline or mixture mineral substances with low-melting temperature can be formed during the mineral thermal transformation of coal ash, thus reducing the ash-fusion tem-perature of the slag system.