准东高碱煤气化过程中碱金属迁移与结渣特性实验研究

利用循环流化床对天池木垒高碱煤进行了气化实验研究,获得了天池木垒高碱煤在循环流化床上的结渣特性及碱金属迁移规律,并对实验中出现的床内颗粒聚团现象进行了分析。结果表明,不同存在形态的碱金属在煤气化过程中的迁移规律不同,水溶钠和醋酸铵溶钠在煤气化过程中以气态形式析出,不溶钠主要存在半焦中;随着气化温度升高,底渣和煤气中钠含量增加,飞灰中钠含量减少;尾部管道温度降低过程中,煤气中钠的冷凝速率明显高于钾;天池木垒高碱煤气化过程中容易引起床内颗粒聚团,床温越高,颗粒聚团现象越明显,床温波动越大;碱金属与灰分中矿物成分及床料中SiO₂反应生成黏性低温共熔物是导致颗粒聚团的关键。

Alkali metal migration and slagging characteristic during Zhundong high-alkali coal gasification

The Tianchi Mulei high-alkali coal gasification in a circulating fluidized bed (CFB) was conducted to study the operating characteristic and the migration of alkali metals, and the phenomenon of bed particles agglomeration was examined by some analytical technologies. The results show that the water-soluble and ammonium-acetate-soluble Na is released into gas while the insoluble Na is mainly remained in semi-char, indicating that the transformation of alkali is different for different modes of occurrence. At higher gasification temperature, both of Na existed in slag and gas become more, while the Na in fly ash declines. The condensation rate of Na in gas phase is higher than that of K with the decreasing of down stream temperature. It seems that the degree of agglomeration increases with the increase of temperature, resulting in bed temperature fluctuation. The eutectic with strong viscosity, formed by a direct reaction between alkali and mineral component of ash or SiO₂ of bed material, is considered as the key factor leading to the agglomeration of particles.