洁净煤技术

2019, (05) 47-52

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棒状型煤抗碎强度影响因素试验研究
Experimental study on factors affecting the mechanical strength of coal pellets

王自祥;付亮亮;宋瑞领;庞明瑾;许文波;王超;蓝天;
WANG Zixiang,FU Liangliang,SONG Ruiling,PANG Mingjin,XU Wenbo,WANG Chao,LAN Tian

摘要(Abstract):

民用散煤利用效率低,燃烧过程产生大量污染物,也是产生雾霾的重要原因之一,推广洁净型煤是治理散煤的有效途径。为了研究棒状型煤的最优制备条件,以兖矿集团南屯动力煤为原料,经锤破制粉系统制得0~5 mm原料煤粉,利用ZLSP200A型平模颗粒机制备棒状型煤,研究了原料水分、粒度、模具锥角和黏结剂等因素对棒状型煤抗碎强度的影响。结果表明:原料煤中水分可润湿煤粉颗粒表面,挤压成型过程中,在煤粉颗粒之间形成稳定的桥接力,同时起到润滑作用。原料煤水分为15%时,成型过程顺畅且棒状型煤初始强度最高,水分过低不能成型或堵塞模孔,水分过高棒状型煤初始强度不足,发生变形、黏连,不能满足储运要求;原料煤粉粒度分布模数m<0.3时,利用电镜观察发现细粒级煤粉密实填充于粗粒级煤粉之间,煤粉颗粒之间接触紧密,颗粒间的桥接力和啮合力强,棒状型煤抗碎强度达90%以上;棒状型煤抗碎强度随模具锥角的增大略微提高,但锥角变大会导致成型过程压辊压力在垂直于锥面方向的分力变大,平行于锥面方向的分力变小,成型过程需要克服的摩擦力增大,能耗及模具磨损增加,在生产中要兼顾型煤抗碎强度与生产平顺性,锥角以16°为宜;黏结剂对棒状型煤抗碎强度有明显的提升作用,添加量在2%~3%时性价比最高。通过不同黏结剂棒状型煤的TG曲线可以看出,有机黏结剂可降低棒状型煤燃点,促进燃烧过程;无机黏结剂使型煤燃点提高,燃烧速率降低,燃尽温度提高,灰分增加,灰熔融温度降低,抑制燃烧过程,生产中可根据用户对型煤抗碎强度、热值、热稳定性的要求及黏结剂价格综合考量选择。
The low utilization efficiency of civil bulk coal and the large amount of pollutants produced in the combustion process are also one of the important reasons for haze. Promoting clean briquette is an effective way to control bulk coal. In order to study the optimum preparation conditions of rod-shaped coal pellets,with Pulverized Coal from the Nantun coal mines of Yankuang Group as raw material,the 0-5 mm raw coal powder was prepared by hammering pulverizing system,and the ZLSP200A flat die pelletizer was used to produce rod-shaped coal pellets. The effects of raw material moisture,particle size distribution,mold taper angle and binder type and amount on crushing strength of rod briquette were experimentally studied. The results show that the moisture in the raw coal can wet the surface of pulverized coal particles and a stable bridge force is formed between pulverized coal particles during extrusion forming process. It also plays a lubricating role. When the moisture content of the raw coal is 15%,the briquetting process is smooth,and the initial strength of rod briquette is the highest. The too low moisture content cannot form or plug the die holes,and the too high moisture content cannot meet the storage and transportation requirements of rod briquette due to insufficient initial strength,deformation,adhesion. When the particle size distribution modulus(Gates-Gaudin- Schutzmann equation)is less than 0.3,it can be found by electron microscope that fine-grained pulverized coal is compactly filled between coarse-grained pulverized coal,and the contact between pulverized coal particles is close,and the bridging force and meshing force between particles are strong,the strength of rod briquette reaches over 90%. It was found that although the pellets strength of rod-shaped briquette increases slightly with the mold cone angle,but the change of cone angle will lead to the increase of the component force of roller pressure in the direction perpendicular to the cone surface,and the component parallel to the cone becomes smaller and the friction is increased in forming process. With the increase of energy consumption and die wear,the briquette crushing strength and production smoothness should be taken into account in production,and the optimum mold cone angle is 16 degrees. Theuse of the binder can greatly improve the strength of the pellets,the best performance-price ratio is between 2% and 3%. From the TG curves of rod-shaped coal pellets with different binders,it can be seen that the organic binders can reduce the burning point of rod-shaped coal pellets and promote combustion process. Inorganic binders can increase the burning point of rod-shaped coal pellets,reduce the burning rate,increase the burnout temperature,increase the ash content,decrease the ash melting temperature and inhibit the combustion process. Considering the costs and its effects on pellets energy content and thermal stability,the comprehensive analysis about the binder type and adding amount are recommended.

关键词(KeyWords): 棒状型煤;抗碎强度;成型技术;提质
coal pellets;mechanical strength;molding technology;quality improvement

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作者(Author): 王自祥;付亮亮;宋瑞领;庞明瑾;许文波;王超;蓝天;
WANG Zixiang,FU Liangliang,SONG Ruiling,PANG Mingjin,XU Wenbo,WANG Chao,LAN Tian

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