不同压力下榆神地区富油煤原位热解产物特性

doi:10.16085/j.issn.1000-6613.2024-1017

摘要/Abstract

摘要：

运用加压反应装置和分子动力学等方法模拟富油煤地下原位热解的气体压力环境，探索富油煤在不同压力下的热解特征。在实验室选用粒度1mm的富油煤为原料，利用加压热重仪和高压反应釜模拟富油煤的原位热解，采用分段法对富油煤不同压力下的热解活化能进行了计算并使用ReaxFF数值模拟分析不同压力下的富油煤分子的热解过程。讨论了不同压力、温度、焦油收率和焦油成分特征之间的关系。研究发现，热解压力的变化对富油煤的热解活化能影响有限，而对产物特性有显著影响。富油煤热解形成半焦的反应中热解第一阶段活化能随热解压力的增大而略微降低，在热解第二阶段活化能随压力增大而增加，增幅亦不大。在模拟富油煤原位热解条件下，600℃时的最大产油率为9.54%。在2MPa时，随着压力的增加，最大产油率降至5.42%，焦油中多环芳烃含量随压力的增大而增加。通过对富油煤在不同温度压力下进行分子动力学模拟，得到与实验相近的热解趋势。分子动力学模拟中产焦油总量在2000K以内随温度上升而增加，在每个温度点焦油产量随压力增加呈现下降趋势，在2000K、3MPa工况下产焦油量达到最大值23.67%，对应实验条件600℃常压下的焦油产出最大值。ReaxFF数值模拟结果表明，温度越高压力的影响越明显，在2300K下产生气体量与压力成反比，产焦油量相较2000K开始下降。本研究完成加压状态下富油煤的热解相关实验，并用分子动力学模拟的方法得到的加压状态下富油煤热解结果相佐证，为富油煤原位热解方面研究提供数据支持。

关键词: 富油煤, 原位热解, 加压热解, 分段活化能, 反应力场

Abstract:

The gas pressure environment of in situ pyrolysis of tar-rich coal under different pressures was simulated by means of pressure reaction apparatus and molecular dynamics. In the laboratory, tar-rich coal with particle size of 1mm was selected as raw material, pressurized thermogravimeter and high pressurized reactor were used to simulate the in situ pyrolysis of tar-rich coal, and the pyrolysis activation energy of tar-rich coal under different pressures was calculated by sectioning method. ReaxFF numerical simulation was used to analyze the pyrolysis process of tar-rich coal molecules under different pressures. The relationships among different pressure, temperature, tar yield and tar composition characteristics were discussed. It is found that the change of pyrolysis pressure has a limited effect on the pyrolysis activation energy, but has a significant effect on the product characteristics. The activation energy of tar-rich coal pyrolysis to form semi-coke is slightly lower with the increase of pyrolysis pressure at first stage of pyrolysis, and at second stage of pyrolysis the activation energy modestly increases with the increase of pressure. The maximum oil yield is 9.54% at 600℃ under simulated in situ pyrolysis conditions of tar-rich coal. At 2MPa, the maximum oil yield decreases to 5.42% with the increase of pressure, and the content of PAHs in tar increases with the increase of pressure. Through molecular dynamics simulation of tar-rich coal under different temperature and pressure, the pyrolysis trend similar to the experiment is obtained. In the molecular dynamics simulation, the total amount of tar increases with the increase of temperature within 2000K, and the tar production at each temperature point shows a downward trend with the increase of pressure. The tar production reaches a maximum of 23.67% at 2000K and 3MPa, corresponding to the maximum tar output at 600℃ and atmospheric pressure under experimental conditions. ReaxFF numerical simulation results show that higher temperature leads more obvious influence of pressure. At 2300K, the amount of gas produced is inversely proportional to the pressure, and the amount of tar begins to decline compared with that at 2000K. In this study, experiments related to pyrolysis of tar-rich coal under pressure were completed, and the results of pyrolysis of tar-rich coal under pressure were supported by molecular dynamics simulation, which can provide data support for the research on in situ pyrolysis of tar-rich coal.

Key words: tar-rich coal, in situ pyrolysis, pressurized pyrolysis, sectioning method for activating energy, reaction force field

中图分类号:

TQ530.2

郝静远, 齐宝金, 魏进家. 不同压力下榆神地区富油煤原位热解产物特性[J]. 化工进展, 2024, 43(S1): 268-281.

HAO Jingyuan, QI Baojin, WEI Jinjia. Characteristics of in situ pyrolysis products of tar-rich coal in Yushen area under different pressures[J]. Chemical Industry and Engineering Progress, 2024, 43(S1): 268-281.

图/表 15

图1 加压热解反应釜系统1—氮气储气罐；2—减压阀；3—质量流量计；4—进气阀；5—压力表；6—安全阀；7—出气阀；8—减压阀；9—测温管

图2 高压反应釜（左）油气冷凝收集（中）及未加工的富油煤原煤（右）

表1 富油煤的元素分析及工业分析

C/%	H/%	O/%	N/%	S/%	水分(M_ad)/%	灰分(A_ad)/%	挥发分（V_da）/%	固定碳(FC_ad)/%	R_max平均值
73.18	5.07	19.16	1.05	1.54	1.23	4.42	37.74	56.96	0.625

图3 恒之HZ-6300型高压热重分析仪

图4 单个富油煤分子（C355H332O57N4S）

图5 富油煤6分子系统

表2 不同压力下液相产物产率

高压反应釜压力/MPa	400℃		500℃		600℃
高压反应釜压力/MPa	焦油/%	水分/%	焦油/%	水分/%	焦油/%	水分/%
0.1	5.82	9.31	8.64	10.96	9.14	10.78
1	3.52	10.50	6.34	11.77	7.17	13.73
2	3.02	9.67	5.56	12.71	6.97	11.76

图6 不同温度压力下煤热解主要气体产物产量变化

图7 不同温度压力下焦油GC-MS组分变化

图8 常压、1MPa、2MPa条件下热重曲线

图9 热解第一阶段与热解第二阶段活化能拟合曲线

表3 不同压力下分段活化能及指前因子

不同热解压力/MPa	T/℃	E /kJ·mol^-1	A/s^-1	相关系数R²
0.1	热解第一阶段（150~350℃）	17.388	3.5726×10^-3	0.9901
0.1	热解第二阶段（350~650℃）	62.745	6.6410×10^-5	0.9911
1	热解第一阶段（150~350℃）	17.375	3.5611×10^-3	0.9926
1	热解第二阶段（350~650℃）	64.847	5.0239×10^-5	0.9918
2	热解第一阶段（150~350℃）	17.211	3.5273×10^-3	0.9948
2	热解第二阶段（350~650℃）	66.925	4.6078×10^-5	0.9912

图10 1400K、1700K、2000K、2300K固体质量的变化

图11 不同温度压力条件下各种组分质量占比变化

图12 实验与模拟的产焦油总量变化趋势

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