微波提质褐煤复吸特性的试验研究

Experimental study on the re-adsorption characteristics of microwave upgraded lignite

为了高效地脱除褐煤中的水分,调控褐煤的界面稳定性,以提高褐煤的品质,将同一微波功率辐照处理后的褐煤在不同相对湿度环境中和不同微波功率辐照处理后的褐煤在同一环境中分别进行复吸试验,探索微波提质后褐煤的复吸机制,并且在这一基础上通过改变处理条件对褐煤的复吸特性进行有效调控。试验表明,褐煤复吸的过程包括扩散和吸附2个环节。环境的相对湿度提高,水蒸气的扩散快,褐煤复吸严重。吸附包括水蒸气与褐煤界面上的极性含氧官能团间的准化学吸附和水蒸气与褐煤表面的吸附,含氧官能团的含量决定褐煤复吸的初始阶段,比表面积是影响褐煤复吸的主要因素。高低功率的配合以及热力预干燥和微波辐照联用的方法均可以经济有效地提高褐煤的界面稳定性,抑制褐煤的复吸。

In order to upgrade the quality of lignite by removing the water and increasing the interface stability with efficient ways, the lignite processed by same microwave power level was put under the environments with different relative humidities and the lignite processed by different microwave power levels was put under the environments with the same relative humidity to re-adsorb the water vapor separately. The mechanism of lignite's re-adsorption was investigated and the re-adsorption was restrained by adjusting the treatment condition. The results indicate that there are two stages (diffusion and adsorption) during the lignite re-adsorption. As the increase of environmental relative humidity, the diffusion of water vapor becomes faster, which results in the serious re-adsorption of lignite. Adsorption contains quasi-chemical adsorption between water vapor and oxygen-containing functional groups on the lignite's interface and adsorption between water vapor and lignite surface. The content of oxygen-containing functional groups decide the incipient stage of re-adsorption while the specific surface area is the main factor of this process. Both the cooperation of high and low power and the combination of thermal drying and microwave irradiation can increase the interface stability and restrain the re-adsorption of lignite economically and effectively. © 2015, China Coal Society. All right reserved.