低变质烟煤与不同类型油共炼反应特性

Co-processing behavior of a sub-bituminous coal with different types of oil

煤油共炼是集煤直接液化和重油加氢转化为一体的高效工艺,对缓解国内石油供需矛盾,平衡能源结构,保障国家能源安全具有重要的战略意义。对比研究了以煤焦油、FCC(催化裂化)油浆、DCC(催化裂解)油浆为油样,分别与一种低变质烟煤共炼的反应特性。结果表明:FCC油浆和煤共炼的煤转化率最高,DCC油浆和煤共炼次之,煤焦油和煤共炼的煤转化率及液体油产率均较低。分析发现,油样中芳香烃的组成和含量不同是导致煤油共炼过程中煤转化率及产物组成差异的主要原因。共炼油样中的多环芳烃的供氢作用是反应过程中自由基加氢的重要途径。多环芳烃先与反应体系中的活性氢原子结合生成氢化芳烃,氢化芳烃则可结合稳定共炼过程中产生的自由基。对油样中1~5环类多环芳烃分析推断,相较于低环数芳烃,油中高环数芳烃供氢能力更强,故4环芳烃含量较高的FCC油浆共炼效果要强于3环芳烃含量较高的DCC油浆。煤焦油中芳烃主要源于煤中芳香结构断键,与煤样具有较好的互溶性,但其高环数芳烃含量较低,氢传递能力弱,导致其与煤共炼时煤转化率及液体油产率相对较低。将FCC油浆和煤焦油掺混作为共炼油时,煤焦油中的芳烃可以保障煤在反应体系中分散,而FCC油浆中的多环芳烃能保障反应体系的供氢能力,2者相互协同促进了煤油共炼过程中煤的转化。

Coal/oil co-processing is an efficient utilization process of coal and heavy oil by coupling direct coal liquefaction with heavy oil hydrogenation conversion.It is an important way for compensating the shortage of oil,balancing the energy structure,and ensuring the national energy security in China.Coal tar,FCC(fluid catalytic cracking)slurry and DCC(deep catalytic cracking)slurry were chosen as oil samples and a sub-bituminous coal was chosen as the coal sample to investigate their co-processing characteristics.The results show that the coal conversion in the co-processing of FCC and coal is the highest,followed by that of DCC and coal,and that of coal tar and coal is the lowest.Further analyses found that the difference of the coal conversion and product composition in coal/oil co-processing is mainly caused by the difference of the aromatic hydrocarbon types and content in the oil samples.The hydrogen donor capacity of the polycyclic aromatic hydrocarbons(PAHs)of the oil samples is the main route to stabilize and protect the free radicals generated in the co-processing technology.The PAHs is favored to combine with the active hydrogen atoms in the reaction system and generated hydrogenated aromatic hydrocarbons,for which has the ability to stabilize the free radicals.It could be deduced from the analysis of the content of the PAHs with 1-5 rings,the FCC with the highest content of 4 ring PAHs has a higher co-processing ability than of the DCC with the highest content of 3 ring PAHs.The aromatic hydrocarbons in coal tar mainly come from the broken bonds of the aromatic structure of the coal,which has good solubility with the coal sample.However,the content of the higher-ring-number PAHs in coal tar is low,and the hydrogen donor capacity is weak,which leads to relatively low coal conversion rate and liquid oil yield when coal tar is co-processed with coal.When FCC and coal tar are mixed as the oil sample for co-processing,the aromatic hydrocarbons in coal tar can ensure the good dispersion of coal,and the higher-ring-number PAHs in FCC slurry can guarantee the hydrogen donor capacity.The synergy of the FCC and coal tar promotes the coal conversion in the coal/oil co-processing.