针对富油煤地下原位热解提油面临高地应力、地质情况复杂以及热解产物分析困难等挑战,设计搭建高温三轴试验装置模拟富油煤地下原位热解工况。试验装置包括高温高压供气模块、原位热解模块、伺服控制模块以及产物分离冷却模块。以陕北神府富油煤为研究对象,基于高温三轴试验装置模拟了不同埋深深度下的高温高压热解试验。高温三轴仪能够提供0~15MPa的轴压(埋深深度0~600m),应力加载响应迅速并且在热解过程中能够保持稳定。实验时高温三轴仪可以加热煤样中心温度至600℃左右,能够实现富油煤在设定的温度下进行热解实验。模拟埋深深度从100m增加到300m,轴压从2.45MPa增加到7.35MPa,热解半焦产率从67.70%升至68.04%,焦油产率呈现先升高后下降趋势,最高为6.50%。埋深增加时焦油中轻油、酚油含量逐渐增加,分别从19%和9.5%增加至25%和12%;沥青在焦油中的比例从25%降低到20%;芳香烃含量从32%升高至38%,脂肪烃含量从28.5%降低到19.3%。煤层渗透率随地应力增加而降低,阻碍热解过程中的传热和传质,导致富油煤热解产物停留时间增加,焦油二次反应,长链脂肪烃化合物发生断裂转化为小分子化合物,甲基、亚甲基同样不断脱出;另一方面应力促进了焦油分子缩合反应的发生,多环芳烃的含量迅速提高。地应力增加提高了轻质芳烃及焦炭的产率,焦油品质向轻质化提升。

Given the challenges faced by in-situ pyrolysis of tar-rich coal,such as high ground stress,complex geological conditions,anddifficult analysis of pyrolysis products,a high-temperature triaxial test device was designed and built independently to simulate the in-situpyrolysis process of tar-rich coal. The test device includes a high-temperature and high-pressure gas supply module,an in-situ pyrolysismodule,a servo control module,and a product separation and cooling module. Taking the Shenfu tar-rich coal in Northern Shaanxi Province as the research object,the pyrolysis experiments of high temperature and high stress under different burial depths were simulatedbased on the high-temperature triaxial test device. The results show that the high-temperature triaxial apparatus can provide axialcompression of 0~15 MPa (buried depth of 0~600 m). The loading response is rapid,and the stress can remain stable duringpyrolysis. During the experiment,the high-temperature triaxial apparatus can heat the central temperature of coal samples over 600 ℃,and can realize the pyrolysis experiment of tar-rich coal at the set temperature. When the simulated burial depth increased from 100 m to300 m,the axial stress on coal samples increased from 2.45 MPa to 7.35 MPa,the yield of pyrolysis semi-coke risen from 67.70% to68.04%,and the tar yield first increased and then decreased,with the highest value of 6.50%. With the increase of simulated burial depth,the contents of light oil and phenol oil in tar gradually increased from 19% and 9.5% to 25% and 12% respectively. The proportion of pitchin tar is reduced from 25% to 20%; The aromatic hydrocarbon content increased from 32% to 38%,and the aliphatic hydrocarbon contentdecreased from 28.5% to 19.3%. The permeability of coal seam decreases with the increase of stress,which hinders the heat and masstransfer in the pyrolysis process,leading to the increase of residence time of pyrolysis products of tar-rich coal,the secondary reaction oftar,the fracture of long-chain aliphatic hydrocarbon compounds and the transformation of methyl and methylene into small molecularcompounds. On the other hand,stress promotes the condensation reaction of tar molecules and the content of polycyclic aromatichydrocarbons increases rapidly. The increase of in-situ stress improves the yield of light aromatics and coke,and the quality of tar isimproved to light weight.