矿物质酸性组分对离子交换态Ca在煤热解过程中反应行为的影响机制研究OA

Inherent minerals play a significant role in the thermal conversion of coal.However,the influence mechanism of the interactions among minerals on the generation of tar during coal pyrolysis remains unclear.To investigate the mechanism of the effect of acidic mineral components on the behavior of Ca2+during coal pyrolysis,several samples were prepared by HCl and HF washing and Ca2+ion exchanging.The pyrolysis behaviors of the experimental coal samples were examined in a fixed-bed reactor.During the acid washing process,the ash content was effectively reduced,while the contents of organic elements such as carbon and hydrogen were also decreased.The loading of ion-exchangeable calcium enhanced the thermal weight loss rate of the coal sample in the 500-550℃ range,and the corresponding peak temperature shifted from 530 to 514℃ for the coal without Ca.When coal was pyrolyzed at a final temperature of 600℃ with a slow heating rate,kaolinite in acidic mineral components undergoes dehydroxylation to form metakaolin,and the content of small aromatic rings(＜6 rings)in the char pyrolyzed by Ca-loaded coal sample was lower than that of the coal sample after acid washing.Due to the coexistence of acidic mineral components with ion-exchangeable Ca,the content of aliphatic hydrocarbons in the pyrolysis tar of YL-HCl-Ca reached 21.98％,significantly higher than 13.60％in the corresponding pyrolysis tar of YL-De-Ca.From the apparent results,it can be found that the acidic mineral components inhibit the adverse effect of ion exchangeable Ca2+on the lightening of coal tar.