Co-pyrolysis study of oil shale and bituminous coal in fixed fluidized bed reactor

doi:10.11949/0438-1157.20240945

Abstract

Abstract:

The rapid co-pyrolysis process of oil shale and bituminous coal was studied by thermogravimetric analysis, and the surface morphology and elemental composition of semi-coke were analyzed by SEM-EDS. At the same time, the product distribution law of the mixed pyrolysis of oil shale and bituminous coal was explored by using a self-made fixed fluidized bed reactor. The thermogravimetric results show that the synergistic effect is most obvious when oil shale accounts for 20%(mass) in the mixed fast pyrolysis process, and the maximum pyrolysis rate increases as high as 49.18%. The semi-coke morphology showed both massive pore structure and layered texture structure, and the content of carbon, oxygen and silicon on the surface of the micro-area varied in different degrees. The fixed-bed pyrolysis process further reveals the co-pyrolysis mechanism of oil shale and bituminous coal. The inorganic minerals in oil shale promote the removal of carboxyl groups in bituminous coal, significantly reduce the contents of phenols, alcohols and aromatic hydrocarbons in mixed pyrolysis oil, increase the yield of long-chain aliphatic hydrocarbons, improve the oil phase yield and improve the oil quality. Meanwhile, the active H radical in oil shale can increase the light hydrocarbon yield of CH₄ in the mixed pyrolysis gas, and increase the recovery value of pyrolysis gas.

Key words: oil shale, bituminous coal, co-pyrolysis, thermogravimetric analysis, fixed fluidized bed reactor

摘要：

采用自主设计的热重分析天平研究油页岩和烟煤混合快速热解过程，并结合SEM-EDS分析其半焦的形貌特点和元素组成。同时通过自制的固定流化床反应器探究油页岩和烟煤混合热解的产物分布规律。热重结果表明：混合快速热解过程中，油页岩占比20%（质量）时，协同效应最明显，有机物热解过程中的最大热解速率增幅高达49.18%；半焦形貌同时呈现团块状孔隙结构和层状纹理结构，微区表面钠、铝、钙元素含量出现不同程度的变化。固定床热解过程进一步揭示了油页岩与烟煤的混合热解协同机理，油页岩中的无机矿物质可促进烟煤中的羧基脱出，显著降低混合热解油中的酚、醇、芳香烃含量，增加长链脂肪烃收率，提高油相收率并改善油品质量。同时油页岩中的活性H自由基提高了混合热解气相产物中的CH₄的轻烃收率，增大了热解气回收利用价值。

关键词: 油页岩, 烟煤, 混合热解, 热重分析, 固定流化床

CLC Number:

TQ 546.4

Dongling XU, Yue MA, Lu GONG, Guili MA, Jinke WANG, Fengzhi GUO, Haolun WANG, Sijia LI, Shuyuan LI, Changtao YUE. Co-pyrolysis study of oil shale and bituminous coal in fixed fluidized bed reactor[J]. CIESC Journal, 2025, 76(4): 1742-1753.

徐东菱, 马跃, 龚露, 马桂丽, 王金可, 郭丰志, 王浩伦, 李思佳, 李术元, 岳长涛. 油页岩与烟煤混合流化热解实验研究[J]. 化工学报, 2025, 76(4): 1742-1753.

Figures/Tables 19

Table 1 The proximate analysis and ultimate analysis of oil shale and bituminous coal

样品

工业分析/

%（收到基，质量）

元素分析/

%（干基，质量）

Table 2 XRF composition analysis of oil shale and bituminous coal

样品	成分/%（质量）
样品	SiO₂	Al₂O₃	CaO	Fe₂O₃	SO₃	Na₂O	K₂O	MgO
油页岩	74.61	6.57	6.41	4.40	2.93	2.53	0.59	0.45
烟煤	20.59	18.82	13.01	7.27	20.90	15.18	0.61	1.68

Table 3 Fischer assay analysis results of oil shale and bituminous coal

样品	含油率/%	水分/%	半焦/%	气体/%
油页岩	16.33	7.80	68.26	7.61
烟煤	6.54	16.00	65.64	11.22

Fig.1 Self-modified thermogravimetric analyzer

Fig.2 Fixed fluidized bed pyrolysis device and product collection device

Fig.3 TG curves of samples with different blending ratios

Fig.4 DTG curves of samples with different blending ratios

Table 4 Pyrolysis parameters of samples with different blending ratios

样品	T₀/℃	T_max/℃	T_f/℃	R_max/(%/℃)
M	424	520	607	0.1094
Y-20%	461	547	600	0.1632
Y-40%	461	551	600	0.1748
Y-60%	468	576	601	0.2128
Y-80%	472	539	598	0.2446
Y-100%	476	552	593	0.2632

Fig.5 Rapid co-pyrolysis SEM-EDS analysis of samples with different blending ratios

Table 5 Element composition in the semi-coke local surface of samples with different blending ratios

样品	C/%	O/%	Na/%	Al/%	Si/%	Ca/%
M	85.50	10.30	1.79	0.63	0.62	1.16
Y-20%	16.65	38.35	1.88	2.02	12.52	28.58
Y-40%	48.76	20.73	1.08	2.29	19.12	8.02
Y-60%	31.16	30.54	1.00	2.96	27.80	6.54
Y-80%	48.57	28.73	0.63	1.74	14.83	5.50
Y-100%	19.41	39.86	0.74	1.90	19.02	19.07

Fig.6 FTIR analysis of oil shale and bituminous coal kerogen

Fig.7 Product distributions of samples with different blending ratios in fixed fluidized bed reactor

Fig.8 Oil phase product distribution of samples with different blending ratios in fixed fluidized bed reactor

Fig.9 Changes in oils from the co-pyrolysis of samples with different blending ratios

Fig.10 Changes in the oil composition from the co-pyrolysis of samples with different blending ratios

Fig.11 Changes in the gas composition from the co-pyrolysis of samples with different blending ratios

Table 6 Changes in organic components in gaseous products from the co-pyrolysis of samples with different blending ratios

样品	组分/%
样品	CH₄	C₂H₆	C₂H₄	C₃H₈	C₃H₆	C₄H₁₀	C₄H₈	C₅H₁₂	C₅H₁₀	C _n H₂_n₊₂(n≤5)	C _n H₂_n (n≤5)	C _n H₂_n₊₂/C _n H₂_n (n≤5)
M	9.06	3.20	1.25	1.26	1.10	0.43	0.61	0.22	0.10	14.17	3.06	4.63
Y-20%	10.05	3.48	1.52	1.31	1.26	0.41	0.48	0.15	0.25	15.40	3.51	4.39
Y-40%	11.06	4.31	2.08	1.64	1.83	0.72	1.19	0.23	0.61	17.96	5.71	3.15
Y-60%	11.28	5.25	2.68	2.06	2.34	0.78	1.51	0.36	0.78	19.73	7.31	2.70
Y-80%	13.19	6.08	3.49	2.29	2.88	0.80	1.43	0.31	0.73	22.67	8.53	2.66
Y-100%	13.51	7.39	3.90	2.88	3.46	1.03	1.80	0.37	0.92	25.18	10.08	2.50

Fig.12 Composition of oil shale and bituminous coal

Fig.13 Co-pyrolysis mechanism of oil shale and bituminous coal

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