准东煤水热提质及废液催化气化特性研究

Study on hydrothermal upgrading of Zhundong coal and catalytic gasification characteristics of its derived liquid

准东煤的碱金属(特别是Na、Ca)含量高,直接作为动力煤燃烧会导致严重的锅炉沾污、结渣。采用水热提质方法能够有效脱除煤中碱金属,同时还可改善煤质的理化特性,但水热提质也会产生大量废液,并导致有机质损失,原料的能量利用率低,限制了该方法的应用。针对上述问题,将水热提质技术与废液气化技术进行耦合,在水热反应釜和自制的两段式反应装置上开展了准东煤水热提质改性及衍生废液催化气化的试验研究,探究了提质后三相产物的分布特性及废液的催化气化特性。结果表明,随着水热温度的升高,煤样的固体回收率降低,废液中总有机碳(TOC)和气体产物显著增大,但至少有97.8%的碳元素分布在固相产物中。废液催化气化产生了富含CH_4、H_2的可燃气,最高占比达到70%。Ni/C催化剂中Ni元素对废液的气化起催化作用,催化效率随着水热温度、气化温度的升高而升高,随液时空速的升高而降低。优选的催化气化试验条件:Ni/C催化剂、水热温度为300℃、催化气化温度为350℃和液时空速为150 h-1。总之,水热提质-废液催化气化联用技术既可以实现煤质的改性,又回收了废液中的能量,能够为准东煤的清洁、高效利用提供新的思路。

Zhundong coal(ZD)has a high content of alkali metals(especially Na and Ca),and its direct combustion as steam coal will cause serious boiler contamination and slagging.The hydrothermal upgrading method can effectively remove alkali metals from coal and can also improve the physical and chemical properties of coal,therefore,it has been widely studied.However,hydrothermal upgrading will also generate a large amount of waste liquid,resulting in the loss of organic matter and low energy efficiency of raw materials,which limits the application of this method.In response to the above problems,the hydrothermal upgrading technology was coupled with the waste liquid gasification technology,and the experimental research on the hydrothermal upgrading of ZD and the derived waste liquid catalysis on the hydrothermal reactor and the self-made two-stage reactor was carried out.The distribution characteristics of the three-phase products after upgrading and the catalytic gasification characteristics of the waste liquid were also explored.The results show that as the hydrothermal temperature increases,the solid recovery rate of coal samples decreases,and the total organic carbon(TOC)and gas products in waste liquid increase significantly,but at least 97.8%of carbon elements are distributed in solid phase products.Catalytic gasification of waste liquid produces combustible gas rich in CH 4 and H 2,with the highest proportion reaching 70%.It is found that Ni element in Ni/C catalyst plays a catalytic role in the gasification of waste liquid.The catalytic efficiency increases with the increase of hydrothermal temperature and vaporization temperature,and decreases with the increase of liquid hourly space velocity.The preferred catalytic gasification experimental conditions are:Ni/C catalyst,hydrothermal temperature of 300℃,catalytic gasification temperature of 350℃and liquid hourly space velocity of 150 h-1.In short,the combined technology of hydrothermal upgrading-waste liquid catalytic gasification technology(HT&CHTG-Process)can not only realize the modification of coal quality,but also recover the energy in the waste liquid,which can provide new ideas for the clean and efficient utilization of ZD.