洁净煤技术

2019, (04) 20-25

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长焰煤热碎半焦的成型-干燥特性研究
Research on molding-drying characteristics of heat fragmentation semi-coke of flame coal

曲洋;
QU Yang

摘要(Abstract):

低阶煤热解后易碎裂及粉化,导致大量热碎半焦的生成,其运输半径短、易形成扬尘并伴有自燃,热碎焦难利用已成为制约热解技术发展的瓶颈之一。对热碎半焦进行成型充分利用热碎焦的天然梯级粒度分布,解决了产品输配难的问题,同时作为洁净煤产品可广泛应用于目前农村地区的散煤替代,是最经济有效的解决途径。以长焰煤热碎半焦为对象,定量研究了长焰煤热碎半焦的成型-干燥特性。选择水溶性黏结剂腐植酸钠和具有较好热态强度及稳定性的无机黏结剂膨润土作为复合黏结剂,通过成型压力机测试了不同黏结剂配方下的型煤冷压强度,采用鼓风干燥法明确了最优干燥制度,最后进行了50 kg成型中试验证。结果表明:腐植酸钠与膨润土复配的黏结剂成型效果优于单种配方,最佳成型配比为腐植酸钠6%、膨润土5%,相应的成型水分为28%、成型压力为20 MPa、粒度上限3 mm的煤粉中低于1 mm比例为65%;型煤采用3个温度区间的干燥制度,避免了干燥温度跃升过快造成的型煤内外变形速率大和裂纹多、机械强度降低等问题,最优干燥制度条件为:起始温度60℃下0. 5 h、过渡温度100℃下1 h、最终温度130℃下1. 5 h。采用最佳的成型和干燥条件进行中试验证,获得的热碎半焦型煤挥发分为10. 55%(≤12%),发热量为28. 97 MJ/kg(≥24 MJ/kg),硫分为0. 33%(≤0. 5%),冷压强度为459 N (≥400 N),灰分为11. 69%(≤25%),各项指标均优于GB34170—2017《商品煤质量民用型煤》和DB 11/097—2014《低硫煤及制品》,论证了该工艺方法的可行性。
Low-rank coal is prone to fragmentation and pulverization during pyrolysis,resulting in the formation of a large amount of pyrolysis semi-coke.Its short transport radius,easy formation of dust and self-ignition,and difficulty in utilization have become the bottleneck restriction the development of pyrolysis technology.The formation of heat fragmentation semi-coke can fully utilize the natural size distribution of semi-coke,which solves the problem of product transport.At the same time,as a clean coal product,it can be widely used as a substitute for bulk coal in the current rural area,which is an effective and economic solution.In this paper,the molding-drying characteristics of heat fragmentation semi-coke of long flame coal were quantitatively investigated.The water-soluble binder sodium humate and the inorganic binder bentonite with good thermal strength and stability were selected as composite binders.The cold compressive strength of the briquette under different binder formulations was tested by forming press.The optimum drying system was determined by blast drying method,and finally a 50 kg molding test was carried out.The experimental results show that the formation effect of composite binders of sodium humate and bentonite is better than that of single formulation,and the optimum molding conditions for flame coal are 6% sodium humate,5% bentonite,28% moisture content,20 MPa molding pressure and 65% (<1 mm) particle size ratio.The briquette is dried in three temperature ranges,avoiding the problems of large deformation rate,more cracks and lower mechanical strength of briquette caused by too fast jump of drying temperature.The optimal drying system for coal is 0.5 h at the initial temperature of 60 ℃,1 h at the transition temperature of 100 ℃,and 1.5 h at the final temperature of 130 ℃.The pilot test was carried out by the above-mentioned molding-drying method,and the results show that the volatilization of the heat fragmentation semi-coke coal is 10.55% (≤12%) and a calorific value is 28.97 MJ/kg(≥24 MJ/kg),the sulfur content is 0.33%(≤0.5%),the cold compressive strength is 459 N(≥400 N),the ash is 11.69% (≤25%),which are superior to the national standards(GB 34170—2017) and Beijing local standard(DB 11/097—2014).The feasibility of the process is demonstrated.

关键词(KeyWords): 长焰煤;热碎;半焦;成型;干燥;中试
flame coal;heat fragmentation;semi-coke;molding;drying;pilot scale test

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作者(Author): 曲洋;
QU Yang

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