添加剂对催化气化工艺中煤灰结渣性及气化性能影响研究

Effect of additives on ash sintering behaviors and gasification performance in catalytic coal gasification process

煤催化气化工艺中碱金属催化剂的引入加剧了气化炉的结渣,直接影响了流化床气化炉的正常操作。煤灰的烧结特性是流化床气化炉结渣的主要影响因素之一。通过自制的压差法烧结温度测定实验装置,并结合XRD等分析表征及Factsage热力学软件模拟计算,考察了不同添加剂对煤灰烧结特性及气化性能的影响,并从矿物学角度探讨了添加剂对煤灰结渣特性及气化工艺的影响。结果表明,添加硅铝系添加剂可提高煤灰的烧结温度;相比硅系添加剂,添加高铝系添加剂对改善煤灰的烧结温度效果更明显;高铝系添加剂可作为一种高效的阻熔剂,但因在气化过程中容易同催化剂反应,导致催化剂催化性能降低,对煤的气化活性及催化剂回收率产生不利影响;添加氧化钙添加剂,煤的灰熔温度及烧结温度均增加,随氧化钙含量增加,灰熔点及烧结温度均升高,且对气化活性及催化剂回收率有良性作用;氧化钙可作为改善煤种结渣性的添加剂用于催化气化工艺中,需根据煤种性质及工艺特点确定适宜的添加量。

The introduction of alkali metal catalyst in the coal catalytic gasification process exacerbates the slagging of the gasification furnace and directly affects the normal operation of the fluidized bed gasifier. The sintering characteristic of coal ash is one of the main factors affecting slag formation in fluidized bed gasifier. In this paper a self-made pressurized pressure-drop measuring device combining analysis of X-ray diffractometer (XRD) analyzer and simulation calculation of Factsage thermodynamic software were used to study the effects of different additives addition on sintering temperature of Wangjiata bituminous coal from Inner Mongolia and gasification performance in catalytic coal gasification process. Silicon aluminum additives improved the sintering temperature of coal ash. Compared with silicon additives, the addition of high aluminum additives had more obvious effect on improving the sintering temperature of coal ash. High aluminum additives can be used as an efficient refractory flux, but it reduced coal gasification activity and catalyst recovery rate, it was because of the reaction of additives with catalyst in gasification, and thus the catalytic performance of catalyst decreased. Addition of calcium oxide, the ash fusion temperature and sintering temperature of coal ash increased, and the coal gasification activity and catalyst recovery rate also improved. The ash melting point and sintering temperature increased with the increase of CaO content. Calcium oxide can be used as an additive to improve the slagging properties of coal in catalytic gasification process. And the additive content should be determined according to the nature of coal and the characteristics of the coal gasification process.