微波在煤泥低温脱水提质的应用研究

利用微波能对煤泥低温脱水提质,探讨了微波干燥的影响因素;分析了微波干燥对煤泥性质的影响;寻求煤泥资源化利用的途径。微波时间、功率和煤泥形状、质量对微波干燥效果影响显著。在微波作用下,煤中水分的蒸发过程分三个阶段:煤加热,外在水分减少,内在水分减少,因而干燥速度较快。烘干重量为200g,水分25%的煤样所需时间不超过700s。试验表明:干燥200s后,煤样温度可达110℃;600s后,温度可达240℃。不仅蒸发了水,也排出了挥发成分。煤泥在微波低温干燥条件下具有较好的脱水效果,干燥后煤泥的含水率和热值提升幅度均达到了预期目标,证明了微波在煤泥干燥提质方面应用的可行性。煤泥微波脱水后,由于微波加热在加热物料内形成的特殊传热传质机理,煤泥内部的矿物盐等会在煤泥表面积聚,形成"硬壳",煤泥不易粉化、破碎,且水分回吸不明显,有助于后续运输和利用。

Application of Microwave in Research of Coal Slime Low-Temperature Dehydration Upgrading

Using the dehydration upgrading to the coal slime in low temperature by microwave energy, this paper discusses the influence factors of microwave drying, analyse the microwave drying on the prop- erties of coal slime and seek the ways of coal slime resource utilization. The effects of microwave power, time, and slime shape, quality on microwave drying are significant. By the microwave irradiation, the evaporation process of moisture in coal can be divided into thr6e stages, coal heating, external moisture reduction, internal moisture reduction, thus drying faster. Dry weight of 200 g, 25% moisture content of the coal sample takes less than 700 s. Experiment shows that drying after 200 s, coal sample temperature can reach 110℃ After 600 s, the temperature can reach 240℃. Not only evaporate the water, also discharge of the volatile component. Coal slime has better dehydration result in microwave low temperature and drying conditions, and the moisture content and calorific value increase rate of the dried slime all achieved the expected goals, proved that the feasibility of the application of microwave in drying and upgrading coal slime. After coal slime dewatering by microwave, the mineral salt internal coal slime will gather on the surface of coal slime and form a ＂shell＂ because of the special heat and mass transfer mechanisms in the material that heated by microwave. So the coal will not easy to be broken to powder and the water absorption is not obvious which will contribute to the subsequent transport and utilization.