提质褐煤复吸水及燃烧特性的实验研究
发布时间：2018-11-15 18:47
【摘要】：中国褐煤资源储量丰富,价格低廉,但褐煤具有水分高、热值低、燃烧效率低、易自燃的特点,不利于储存和远距离运输。褐煤提质预处理已成为国内外研究的热点,热解提质即其中的一种简单可靠的处理方式。由于褐煤是一种类似胶质体的多孔性物质,提质煤表面存在大量的孔洞和缝隙,在潮湿的环境中会再次吸水,即产生复吸水现象。研究提质煤的复吸水机理并寻求降低复吸水率的途径,对改善提质煤品质、提高褐煤的利用效率有重要意义。本文选取收到基水分为52.3%的云南昭通褐煤为研究对象,进行低温热提质(提质温度为200-500℃),提质前分别使用三种方式对原煤进行预处理,以期达到降低提质煤复吸水率的目的。从物理结构角度使用沥青负载处理,从化学结构角度分别使用盐酸、硼氢化钠预处理。实验采用傅里叶转换红外光谱(FTIR)分析了提质过程中煤表面含氧官能团OH和C=O相对含量的变化,采用氮气等温吸附法和扫描式电子显微镜(SEM)分析了提质煤的孔隙结构和表面形貌特征变化。使用恒温恒湿箱测试了提质煤的复吸水特性,使用TG-DTG系统分析了提质煤样的燃烧特性。研究表明:1)随着提质温度的升高,褐煤中的含氧官能团C=O和OH含量逐渐减少,提质煤的孔容积和比表面积逐渐增大,平均孔径逐渐减小;提质煤的复吸水率和自燃倾向都逐渐降低;2)盐酸预处理提高了提质煤的发热量,降低了提质煤中的OH含量,显著降低了提质煤的复吸水率,降低了自燃倾向和反应活性、提高了燃烧剧烈程度和燃尽性能;3)硼氢化钠预处理抑制了挥发分的析出,降低了提质煤的发热量;抑制了微孔的生成和发展,对降低复吸水率的作用较小,提高了褐煤的自燃倾向,降低了燃尽性能、燃烧反应活性和燃烧剧烈程度;4)沥青负载处理抑制了微孔的生成,降低了提质煤的比表面积,沥青对提质煤的复吸水特性表现在极性影响和负载影响两个方面,在200-300℃提质时,沥青浓度高于5wt%时才能降低复吸水率,在400-500℃时,提质煤的复吸水率随沥青浓度的升高而降低,沥青负载处理对提质煤燃烧特性的影响取决于热解温度区间。
[Abstract]:Lignite resources in China are rich in reserves and low in price, but lignite is characterized by high moisture content, low calorific value, low combustion efficiency and easy spontaneous combustion, which is not conducive to storage and long-distance transportation. The pretreatment of lignite has become a hot spot at home and abroad, and pyrolysis is one of the simple and reliable methods. Because lignite is a kind of porous material similar to colloid, there are a large number of holes and gaps on the surface of the coal, which will absorb water again in the wet environment, that is, the phenomenon of reabsorption. It is of great significance to study the mechanism of reabsorbing water and to find a way to reduce the rate of water absorption. It is of great significance to improve the quality of extracted coal and improve the utilization efficiency of lignite. In this paper, Yunnan Zhaotong lignite, which is divided into 52.3% basic water, is selected as the research object. The raw coal is pretreated with three methods before the pretreatment, which is carried out at low temperature (200 ~ 500 鈩，
本文编号：2334133
[Abstract]:Lignite resources in China are rich in reserves and low in price, but lignite is characterized by high moisture content, low calorific value, low combustion efficiency and easy spontaneous combustion, which is not conducive to storage and long-distance transportation. The pretreatment of lignite has become a hot spot at home and abroad, and pyrolysis is one of the simple and reliable methods. Because lignite is a kind of porous material similar to colloid, there are a large number of holes and gaps on the surface of the coal, which will absorb water again in the wet environment, that is, the phenomenon of reabsorption. It is of great significance to study the mechanism of reabsorbing water and to find a way to reduce the rate of water absorption. It is of great significance to improve the quality of extracted coal and improve the utilization efficiency of lignite. In this paper, Yunnan Zhaotong lignite, which is divided into 52.3% basic water, is selected as the research object. The raw coal is pretreated with three methods before the pretreatment, which is carried out at low temperature (200 ~ 500 鈩，
本文编号：2334133
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