Effect of crude oil immersion on micropore structure of coal

doi:10.16265/j.cnki.issn1003-3033.2023.12.2396

Abstract

Abstract:

In order to study the change law of coal pore structure after crude oil immersion, typical coal samples associated with kerosene mine were selected and immersed in crude oil for different days. The changes of pore morphology, type, pore volume and specific surface area of coal before and after oil immersion were studied by mercury intrusion method and low temperature nitrogen adsorption method, and the microscopic mechanism of crude oil invading coal was revealed by scanning electron microscope (SEM). The research shows that after the coal sample is immersed in crude oil, the mercury entry and exit curve and the low temperature adsorption and desorption curve have obvious weakening trends. The tiny pores of the coal sample change from the original parallel plate pores to the wedge-shaped pores, and the connectivity between the pores becomes worse. With the increase of oil immersion days, the effect of crude oil immersion on coal porosity is obvious. Compared with raw coal samples, the total pore volume of coal samples is reduced by 32%-80%, and the pore volume of macropores and mesopores decreases significantly. The total pore specific surface area of coal samples decreases by 87%-94%, and the specific surface area of small pores and micropores decreases significantly. The flow of crude oil in coal can be roughly divided into three parts: the penetration of large pores and fractures-the filling of medium and large pores-the blockage of small pores.

Key words: crude oil immersion, oil-immersed coal sample, pore structure, pore morphology, pore volume, specific surface area

SHUANG Haiqing, WEI Mengmeng, BAI Yang, ZHANG Jin, TIAN Yu, ZHANG Xing. Effect of crude oil immersion on micropore structure of coal[J]. China Safety Science Journal, 2023, 33(12): 113-121.

Figures/Tables 12

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密度 (20 ℃)/ (g·mL^-1)	黏度 (50 ℃)/ (mm²·s^-1)	凝点/ ℃	组分含量测定
密度 (20 ℃)/ (g·mL^-1)	黏度 (50 ℃)/ (mm²·s^-1)	凝点/ ℃	饱和烃/%	芳香烃/%	沥青质/%	非烃/ %
0.885 1	17.08	-3.5	75.6	11.6	1.24	5.79

煤样编号	煤样	工业分析				元素分析
煤样编号	煤样	水分	灰分	挥发分	固定碳	碳元素	氢元素	氮元素	氧元素
1-1	原煤样	1.98	6.61	35.15	57.09	68.96	4.06	2.25	24.46
2-1	浸油煤样1	2.21	5.32	31.84	60.63	83.95	5.24	2.62	7.98
2-2	浸油煤样2	2.19	5.66	32.72	59.43	83.70	5.33	2.02	8.76
2-3	浸油煤样3	2.06	8.19	34.01	55.74	80.10	5.18	2.95	11.52
2-4	浸油煤样4	2.41	8.78	33.76	55.05	80.76	5.02	3.40	10.57

煤样编号	压汞法孔容积				氮吸附法孔容积
煤样编号	微孔	小孔	中孔	大孔	微孔	小孔	中孔
1-1	0.029 19	0.022 32	0.009 31	0.065 65	0.001 174	0.003 527	0.002 098
2-1	0.022 85	0.016 51	0.005 51	0.047 96	0.000 040	0.000 396	0.000 292
2-2	0.026 61	0.011 19	0.001 01	0.021 16	0.000 058	0.000 344	0.000 220
2-3	0.026 86	0.011 05	0.000 98	0.017 31	0.000 026	0.000 313	0.000 309
2-4	0.025 68	0.010 97	0.000 10	0.014 93	0.000 060	0.000 487	0.000 331

煤样编号	压汞法比表面积				氮吸附法比表面积
煤样编号	微孔	小孔	中孔	大孔	微孔	小孔	中孔
1-1	22.504 41	4.398 08	0.240 07	0.004 97	0.974 31	0.496 27	0.047 79
2-1	17.324 71	3.609 67	0.122 22	0.005 25	0.038 92	0.052 81	0.007 37
2-2	20.724 02	3.135 36	0.030 43	0.000 70	0.070 88	0.050 97	0.006 02
2-3	21.107 44	3.062 4	0.029 64	0.000 52	0.026 25	0.040 44	0.007 68
2-4	17.842 84	3.071 03	0.028 97	0.000 55	0.060 16	0.069 18	0.000 79