马瑞原油在空气和氮气中的热解-氧化性能

Characteristics of Pyrolysis-Oxidation Reactions of Merey Crude Oil in Air and Nitrogen

低温氧化是注空气采油及原位燃烧采油技术中的重要化学反应,为深入认识原油在有氧环境下复杂热反应过程中的低温氧化特性,我们采用热重/差热分析法(TG/DTA)研究了线性升温和等温条件下马瑞(Merey)原油的热反应行为。结果表明,Merey原油在空气及线性升温条件下的受热过程分4个阶段:气化段、低温氧化段、热解段和高温氧化段;相邻阶段的物理、化学主导过程的重叠增加了分析原油热反应特征的难度。升温速率提高,气化段和低温氧化段的终止温度不变;热解段和高温氧化段的终止温度以及热解段的峰温随升温速率的增加而升高。N_2气与空气下Merey原油的热重/微分热重(TG/DTG)数据对比表明,升温速率越高,空气下的高温氧化段与热解段重叠程度越大,这有利于燃烧但会降低原油采收率。空气下等温时的TG/DTA结果表明随升温速率增加,升温至300℃时的失重率降低,不利于原油轻组分的气化。反应温度越高,气化过程时间越长,失重分数越大。Merey原油在低于300℃时低温氧化反应不是主导反应。

Low-temperature oxidation is an important chemical reaction in air injection and in-situ combustion processes for enhanced oil recovery. To further understand the low temperature oxidation mechanism of intricate thermal reactions of crude oil in aerobic environment, the thermal behavior of Merey crude oil was investigated by thermogravimetry/differential thermal analysis（TG/DTA） in air and under nitrogen atmosphere . The results show that the four reaction intervals including gasification, low temperature oxidation, pyrolysis and high temperature oxidation are observed for the thermal process of Merey crude oil in air with a linear heating rate. The overlap of dominant physical and chemical processes in adjacent intervals sophisticates the characteristics of the oil thermal reaction. The invariant final temperature of gasification and low temperature oxidation intervals as well as the elevated final temperature of pyrolysis and high temperature oxidation intervals along with a raised peak temperature of pyrolysis interval are obtained as the heating rate increases . The comparison of TG/DTG experiments in air and under N 2 atmosphere show that an increasing overlap of high temperature oxidation and pyrolysis intervals is observed as the heating rate increases, which is in favor of coke combustion but adverse to the enhanced oil recovery. The isothermal TG/DTA results show that the ratio of mass loss at temperature 300 ℃ decreases with the increase of the heating rate in air, which is not conducive to the gasification of light components of oil. The higher isothermal reaction temperature corresponds to the longer process of gasification and the greater mass loss. The oxidation is not the main reaction for Merey crude oil below 300 ℃.