煤系针状焦生产过程中同一生焦周期内焦炭微观结构差异性分析

程俊霞; 赵雪飞; 刘巍; 朱亚明; 高丽娟; 赖仕全

doi:10.19906/j.cnki.JFCT.2021051

煤系针状焦生产过程中同一生焦周期内焦炭微观结构差异性分析

doi: 10.19906/j.cnki.JFCT.2021051

辽宁科技大学化工学院，辽宁鞍山 110451

基金项目: 国家自然科学基金(U1361126)，辽宁省自然科学基金(20180551218)，辽宁省教育厅项目(2020LNQN03)和辽宁科技大学优秀人才培养项目(2018RC07)资助

详细信息

通讯作者:
E-mail: zhao_xuefei@sohu.com

中图分类号: TQ53
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出版历程
- 收稿日期: 2021-01-25
- 修回日期: 2021-03-13
- 网络出版日期: 2021-04-09
- 刊出日期: 2021-08-31

Analysis on the difference of coke microstructure in the same coking cycle during the production of coal-based needle coke

School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China

Funds: The project was supported by the National Natural Science Foundation of China (U1361126), Natural Science Foundation of Liaoning Province (20180551218), Liaoning Provincial Department of Education Project (2020LNQN03), Excellent Talent Training Project of University of Science and Technology Liaoning (2018RC07)

摘要

摘要: 以煤系针状焦生产过程同一生焦周期内八种不同进料时间的混合油为研究对象。采用偏光显微镜定量分析混合油制备针状焦的光学组织结构；扫描电镜（SEM）观察针状焦的形貌；XRD、Raman光谱分析针状焦的微晶结构等手段。研究不同进料时间的混合油转化为针状焦后的质量差异。结果表明，混合油热转化后生焦的收率高于理论计算的收率，说明重油参与了热转化反应。并且形成了以流线型为主的光学组织结构的生焦。生焦煅烧后形成针状焦光学组织结构中含有纤维结构最多的是样品MO-8"；其次是MO-16"，总纤维含量最少的是样品MO-32"。SEM进一步证明了MO-8"的片层数量更多且取向更规整。针状焦的XRD谱图分析表明，针状焦中的微晶结构参数（层间距d₀₀₂, 片层含量N以及每一层中碳原子数n）非常接近。但是趋于规整的石墨微晶含量（I_g）却存在明显的差异，其中MO-8"含量最高；其次是MO-4"，含量最少的是样品MO-32"。Raman光谱分析结果进一步证实了针状焦的基础微观结构相近。其根本原因在于针状焦的基础微观结构由混合油中的精制沥青决定的，但是由于重油在系统内不断循环改变了成焦的环境，造成了针状焦微观结构的差异。因此，煤系针状焦生产中，生焦周期不易超过32 h，否则将严重影响针状焦的微观结构。
- 煤系针状焦 /
- 混合油 /
- 光学组织结构 /
- 微晶结构
Abstract: 8 kinds of mixed oil with different feeding time in the same coking cycle were the objects of the study. The optical structure, morphology structure and microcrystalline structure of needle coke formed by mixed oil with different feeding time in coking cycle were quantitatively analyzed by means of polarizing microscope, scanning electron microscope (SEM), XRD and Raman spectroscopy. The results show that the yield of coke after the thermal conversion of the mixed oil is higher than the theoretically calculated yield, indicating that the heavy oil participates in the thermal conversion reaction to form the coke with a streamlined optical structure. In the optical structure of calcined needle coke, MO-8" has the highest fiber content, followed by MO-16", and MO-32" has the lowest fiber content. SEM further proves that MO-8" has more lamellar number and more regular orientation. XRD analysis of needle coke confirms that the microcrystalline structure parameters (interlayer spacing d₀₀₂, lamellar content N and the number of carbon atoms in each layer n) are very close. However, there are obvious differences in the content of graphite microcrystalline (I_g), and among which MO-8" has the highest content, followed by MO-4", and sample MO-32" has the lowest content. Furthermore Raman spectral analysis certifies that the basic microstructure of needle coke is similar. The fundamental reason is that the refined coal-tar pitch in the mixed oil determines the basic microstructure of needle coke. Due to the continuous circulation of heavy oil in the system, the microstructure of needle coke are different. Hence, the coking cycle is not easy to exceed 32 h in coal-based needle coke production, or else it will seriously affect the microstructure of needle coke.
- coal-based needle coke /
- mixed oil /
- optical structure /
- microcrystalline structure

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FIG. 847. FIG. 847.

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图 1 延迟焦化工艺示意图

Figure 1 Diagram of delayed coking process

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图 2 生焦的收率（a）和挥发分（b）

Figure 2 Yield (a) and volatile (b) of green needle coke

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图 3 生焦的光学组织照片

Figure 3 Optical structure of green needle coke (a): MO-4'; (b): MO-8'; (c): MO-12'; (d): MO-16'; (e): MO-20'; (f): MO-24'; (g): MO-28'; (h): MO-32'; (i): HO'; (j): RCTP'

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图 4 煅烧后针状焦的收率

Figure 4 Yield of needle coke after calcination

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图 5 针状焦的光学组织照片

Figure 5 Optical structure of needle coke (a): MO-4"; (b): MO-8"; (c): MO-12"; (d): MO-16"; (e): MO-20"; (f): MO-24"; (g): MO-28"; (h): MO-32"

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图 6 （a）针状焦中各光学组织的含量，（b）针状焦中纤维总量

Figure 6 (a) Content of optical structure in needle coke, (b) fiber content in needle coke

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图 7 针状焦的扫描电镜图片

Figure 7 Scanning Electron Microscopic images of needle coke (a): MO-4"; (b): MO-8"; (c): MO-12"; (d): MO-16"; (e): MO-20"; (f): MO-24"; (g): MO-28"; (h): MO-32"

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图 8 （a）针状焦的XRD谱图，002峰分峰拟合图（b）MO-8"

Figure 8 (a) XRD spectra of needle coke, (b) 002 peak-fitting spectra of MO-8"

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图 9 （a）针状焦的Raman谱图，（b）MO-8"的Raman拟合谱图

Figure 9 (a) Raman spectra of needle coke, (b) curve-fitted Raman spectrum of MO-8"

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表 1 混合油的基本性质

Table 1 Proximate analysis of mixed oils

Sample	CV^a/%	TI^b/%	QI^c/%	ρ₁₀₀^d/(g·cm⁻³)	M_n^e/( g·mol⁻¹)
MO-4	17.97	1.49	< 0.01	1.137	275.93
MO-8	16.19	1.46	< 0.01	1.138	288.33
MO-12	17.41	1.90	< 0.01	1.138	301.27
MO-16	17.64	1.56	< 0.01	1.141	293.58
MO-20	17.29	2.12	< 0.01	1.138	313.18
MO-24	17.44	2.56	< 0.01	1.138	323.64
MO-28	17.64	2.56	< 0.01	1.143	320.50
MO-32	17.75	2.36	< 0.01	1.145	368.39
^a: Coking value，^b: Toluene insoluble, ^c: Quinoline insoluble, ^d: The density of 100 ℃, ^e: Average molecular weight

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表 2 XRD各参数计算

Table 2 Calculation results of XRD parameters

Sample	d₀₀₂/nm	L_c/nm	L_a/nm	I_g/%	N	n
MO-4"	0.343	2.69	3.85	76.02	7	15
MO-8"	0.340	2.64	4.06	80.63	7	15
MO-12"	0.346	2.69	4.76	51.57	7	15
MO-16"	0.342	2.77	4.83	73.63	7	16
MO-20"	0.347	2.71	3.55	58.70	7	15
MO-24"	0.347	2.69	4.82	59.08	7	15
MO-28"	0.344	2.58	5.49	74.67	7	14
MO-32"	0.349	2.66	4.90	48.62	7	14

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表 3 Raman各参数计算

Table 3 Calculation results of Raman parameters

Sample	I_D1/I_all/%	I_D2/I_all/%	I_D3/I_all/%	I_D4/I_all/%	I_G/I_all/%
MO-4”	51.67	9.27	8.18	10.70	20.19
MO-8”	49.72	5.86	12.12	10.13	22.17
MO-12”	50.72	7.23	12.23	10.48	19.34
MO-16”	48.41	5.31	12.29	10.57	23.42
MO-20”	59.14	5.24	14.90	3.92	16.81
MO-24”	56.70	2.83	15.82	5.69	18.96
MO-28”	40.18	7.54	14.54	19.15	18.59
MO-32”	28.27	0.45	33.01	25.69	12.58
Note: I_X / I_all refers to the ratio of the integral area of X-band to the sum of the integral areas of all bands, which represents the content of X-band

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