五彩湾煤中钠在热解过程中的形态变迁

摘要

The existing forms of sodium in Wucaiwan coal, a high sodium content coal from Zhundong area inXinjiang Uygur Autonomous Regions , China, were determined by three-step-extraction method and by the analysis of microwave digestion and inductively coupled plasma atomic emission spectrometry (ICP-AES). Theexisting forms of sodium in treated samples and the chars were also determined. The transformation of sodium in the raw coal and the treated coals during pyrolysis was investigated. The results show that most of the sodium in Wucaiwan coal exists in the form of water-solution sodium, and the organically bound sodium exists mainly inthe form of carboxylate. During pyrolysis , the release of water soluble sodium and ammonium-acetate soluble sodium from the coal samples mainly takes place in the temperature range of 650 ~ 850 ℃, and the release oftotal sodium gets to the largest value at 1 050 ℃ accompanied with the releasing of hydrochloric soluble sodium. However, most of the sodium in the treated coal chars exists in the form of insoluble type. The transformation ofa part of water soluble sodium and hydrochloric soluble sodium in all samples into ammonium-acetate soluble sodium during pyrolysis at 450 ~ 650 ℃ can be observed.%采用不同萃取液进行了新疆准东五彩湾高钠煤萃取实验,并利用微波消解仪和电感耦合等离子体原子发射光谱仪,分析了原煤和不同萃取过程下制得的煤样中的钠元素,确定了五彩湾煤中钠的存在形式。在氮气氛围下进行了原煤及不同萃取过程下煤样的热解实验,分析了热解半焦中钠的存在形式并确定煤中不同存在形式钠在热解过程中的演变规律。结果表明,五彩湾煤中钠主要为水溶钠,有机钠主要以羧酸盐形式存在。450~650℃时,实验煤样热解过程中部分水溶钠和盐酸溶钠会转化为醋酸铵溶钠。在热解过程中,实验煤样中水溶钠和醋酸铵溶钠的析出主要集中于650~850℃,1050℃时则有部分盐酸溶钠析出,此时,在实验条件下钠的挥发达到最大值。煤样半焦中的钠主要以不可溶钠形式存在。