微波吸收剂对褐煤微波提质的影响规律

褐煤微波辐照过程中,仅有煤中的水分和微量物组分对微波的吸收能力强,如果在微波辐照过程中添加吸收微波能力强的微波吸收剂,可以加强褐煤微波提质过程。以褐煤半焦和活性炭为微波吸收剂,运用微波干燥试验设备,对锡林郭勒褐煤进行了微波干燥脱水试验研究,分析了微波场中吸收剂对褐煤水分脱除的影响规律,探索了吸收剂对微波提质褐煤的理化特性的提升机理。结果表明:加入微波吸收剂后的微波提质过程依然遵循微波脱水提质的预热,升速和等速干燥;微波提质褐煤的煤质明显提高,含氧官能团数量降低,自燃情况得到抑制。与没添加吸收剂煤样相比,加入微波吸收剂后的提质煤样水分含量降低1.6%、脱水率提高了9.46%、脱水速率提高了0.013%/s;碳元素含量提高2%、氧含量降低0.8%;干燥无灰基低位发热量增加1 059.318 k J/kg和干燥无灰基高位发热量增加了1 059.99 k J/kg;燃点最高可提高23℃。

Enhancement of microwave absorbents on quality of microwave dehydrated lignite

During the process of microwave irradiation on lignite,only the moisture and micro-components in lignite have strong capability to absorb microwave energy.If the absorber with strong microwave absorption ability is added to lignite samples during that process,the microwave upgrading process of lignite can be strengthened.Taking lignite semi-coke and activated carbon as microwave absorber,using microwave drying equipment,the experimental study of Xilin lignite on microwave drying and dehydration is carried out,and the effects of microwave absorber on lignite moisture dehydration in microwave field are analyzed.The enhancement mechanism of the physicochemical properties of upgrading lignite with microwave absorber is explored.The results show that the process of microwave dehydration and upgrading with microwave absorber still follows three stages (preheating stage,rising-rate drying stage,constant-rate drying stage).During the whole drying process,the quality of microwave upgrading lignite is obviously improved,the number of oxygen containing functional groups is reduced,and the condition of spontaneous combustion is suppressed.Compared with lignite samples without microwave absorbent,the moisture of upgrading lignite with microwave absorbent decreases 1.6%,the dehydration rate increases by 9.46%,the dehydration rate of water loss increases 0.013%/s;carbon content increases 2%,the oxygen content decreases 0.8%;the dry-ash-free low heat and the dry-ash-free high heat increase 1 059.318 kJ/kg and 1 059.99 kJ/kg respectively;and the ignition can improve the maximum temperature of 23 ℃.