ABSTRACT

Moisture content in coal powder is a critical index because it controls the difficulty of coal handling and ultimately its combustion efficiency in coal-fired power plants. A unilateral proton nuclear magnetic resonance (NMR) scanner was applied in a laboratory to nondestructively quantify moisture content in powdered samples of brown and subbituminous coals. Due to the open geometry of the sensor unit, the scanner allows the nondestructive moisture quantification of a portion several millimeters below the surface of a large sample. Proton transverse relaxation was measured by the unilateral NMR scanner, and obtained moisture content values were compared with those by a conventional bilateral NMR apparatus. The comparison showed reasonable agreement with a root mean square residual of 4.1 wt.%H₂O for a moisture content range of > 12 wt.%H₂O (wet basis). This moisture-quantification performance by unilateral NMR is sufficient for the quality control of wet coal having a critical value of approximately 30 wt.%H₂O in terms of the handling property (flow-ability). Because unilateral NMR requires no specific sample preparation, such as sample insertion into tubes, the system is potentially applicable to in-situ nondestructive monitoring of the coal moisture in power plants to contribute to improved efficiency of handling and combustion.

摘要

煤粉中的水分含量是一个关键指标，因为它控制着煤炭处理的难度，并最终控制了燃煤电厂的燃烧效率。在实验室中应用单边质子核磁共振 (NMR) 扫描仪对褐煤和次烟煤粉末样品中的水分含量进行无损量化。由于传感器单元的开放式几何结构，扫描仪允许对大样本表面以下几毫米的部分进行无损水分量化。通过单边核磁共振扫描仪测量质子横向弛豫，并将获得的水分含量值与常规双边核磁共振仪进行比较。_{比较显示与 4.1 wt.%H 2}的均方根残差的合理一致性O 对于 > 12 wt.%H ₂ O（湿基）的水分含量范围。这种通过单侧NMR进行的水分定量性能足以用于湿煤的质量控制，其在处理性能（流动性）方面具有大约30wt.%H _{2 O的临界值。}由于单侧核磁共振不需要特定的样品制备，例如将样品插入管中，因此该系统可能适用于发电厂煤水分的原位无损监测，有助于提高处理和燃烧效率。