不同灰成分的低熔点煤灰熔融性调控机理研究

通过灰熔点较低且接近的两种煤与灰熔点较高的天池煤混配,结果表明,在含铁类矿物质较低的小屯煤与天池煤的混煤中,混煤灰熔点随天池煤混入比例的增加而提高,含铁类矿物质较高的宁鲁原煤与天池煤的混煤灰熔点随天池煤混入比例的增加没有明显变化。通过XRD分析配煤中矿物质的转变过程,结果表明,宁鲁原煤灰中含有的钙铁类矿物质(如赤铁矿、硬石膏)抑制了莫来石的生成,缺少作为骨架支撑作用的高熔点莫来石,煤灰的熔点得不到显著提高。最后将配煤在沉降炉中进行实验模拟电站锅炉的结渣过程,并使用SEM分析灰渣的微观形貌,发现与宁鲁原煤相比,小屯与天池煤的混煤更能显著改善结渣特性。

Ash fusion regulation mechanism of coal with low melting point and different ash compositions

Two coals (Ninglu and Xiaotun) with low and close ash fusion temperature were selected and blended with Tianchi coal having a high fusion temperature. The results show that the ash fusion temperature of the blended coal with Xiaotun increases more significantly with increasing ratio of Tianchi coal; and that with Ninglu coal varies little. Mineral transformation processes of blended coal-ashes were examined by XRD. The combustion residue of Ninglu coal contains lots of minerals such as hematite and anhydrite which have negative effects on the formation of mullite. The ash fusion temperature could not increase dramatically for the lack of mullite with high fusion temperature and playing a key supporting role in coal-ash melting. Some experiments of blended coals were carried out in a drop tube furnace to simulate slagging process in power plant boilers. SEM was applied to analyze the surface morphology of different residues. It is proved that Xiaotun coal blended with Tianchi coal could remarkably improve slagging characters.