Reaction characteristics and mechanism of pressurized chemical looping gasification of coal char

doi:10.16085/j.issn.1000-6613.2020-0534

Abstract

Abstract:

Fe₂O₃/Bentonite, which was prepared by mechanical mixing method,was used as oxygen carrier in the coal char chemical looping gasification under pressure in a pressurized fixed bed reactor. The influence of pressure on the reactivity of coal char, the structure and pore structure of coal char were analyzed by means of Raman and N₂ adsorption isotherm line. The reaction mechanism of pressurized chemical looping gasification of coal char is discussed based on the kinetic equation.The results showed that when the total pressure of the system increases from 0.46MPa to 0.80MPa, the rate of char gasification increases from 0.01592min^-1 to 0.03086min^-1; the partial pressure of steam increases by 75%; and the H₂/CO molar ratio by 74%. The gasification process of coal char pressurized chemical looping can be described by Random Pore Model (RPM).As the total pressure of the system increases, the specific surface area of the coal char increases, and the reaction activity of the coal char increases with the increase of the partial pressure of water steam, thus increasing the gasification reaction rate of the chemical looping of the coal char.

Key words: chemical looping, kinetics, syngas, gasification

摘要：

采用机械混合法制备的Fe₂O₃/膨润土为载氧体，在加压固定床中进行煤焦化学链气化试验和动力学研究，借助拉曼和N₂吸附等温线表征手段，分析压力对煤焦反应活性及煤焦碳结构和孔结构的影响，讨论煤焦加压化学链气化反应机理。结果表明：系统总压从0.46MPa增加至0.80MPa时，煤焦化学链气化反应速率从0.0159min^-1提高至0.0309min^-1；水蒸气分压增加75%，H₂/CO摩尔比值增加74%。煤焦加压化学链气化过程可以用随机孔模型（RPM）描述，系统总压增加有利于内部扩散。系统总压增大煤焦的比表面积增加，水蒸气分压增大煤焦的反应活性提高，因而提高了煤焦化学链气化反应速率。

关键词: 化学链, 动力学, 合成气, 气化

CLC Number:

Xiaoli TAN, Mei AN, Xintong GUO, Qingjie GUO, Jianping KUANG. Reaction characteristics and mechanism of pressurized chemical looping gasification of coal char[J]. Chemical Industry and Engineering Progress, 2021, 40(1): 173-182.

谭晓莉, 安梅, 郭欣桐, 郭庆杰, 匡建平. 煤焦加压化学链气化反应特性和机理[J]. 化工进展, 2021, 40(1): 173-182.

Figures/Tables 18

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序号	温度 /℃	系统总压 /MPa	水蒸气分压 /MPa	Ar /L·min^-1	水蒸气 /L·min^-1
1	920	0.80	0.32	1.20	0.80
2	920	0.80	0.40	1.00	1.00
3	920	0.80	0.48	0.80	1.20
4	920	0.80	0.56	0.60	1.40
5	920	0.46	0.32	0.35	0.80
6	920	0.53	0.32	0.53	0.80
7	920	0.64	0.32	0.80	0.80
8	900	0.80	0.40	1.00	1.00
9	880	0.80	0.40	1.00	1.00
10	860	0.80	0.40	1.00	1.00

序号	温度 /℃	系统总压 /MPa	水蒸气分压 /MPa	Ar /L·min^-1	水蒸气 /L·min^-1
1	920	0.80	0.32	1.20	0.80
2	920	0.80	0.40	1.00	1.00
3	920	0.80	0.48	0.80	1.20
4	920	0.80	0.56	0.60	1.40
5	920	0.46	0.32	0.35	0.80
6	920	0.53	0.32	0.53	0.80
7	920	0.64	0.32	0.80	0.80
8	900	0.80	0.40	1.00	1.00
9	880	0.80	0.40	1.00	1.00
10	860	0.80	0.40	1.00	1.00

系统总压 /MPa	组分/%				产率 /%	η /%
系统总压 /MPa	CO₂	CO	H₂	CH₄	产率 /%	η /%
0.46	40.88	4.59	52.60	1.92	59.12	53.08
0.53	42.06	4.47	51.29	2.16	57.93	59.76
0.64	42.48	4.41	50.76	2.36	57.52	65.58
0.80	42.92	4.41	50.26	2.40	57.07	71.48

系统总压 /MPa	组分/%				产率 /%	η /%
系统总压 /MPa	CO₂	CO	H₂	CH₄	产率 /%	η /%
0.46	40.88	4.59	52.60	1.92	59.12	53.08
0.53	42.06	4.47	51.29	2.16	57.93	59.76
0.64	42.48	4.41	50.76	2.36	57.52	65.58
0.80	42.92	4.41	50.26	2.40	57.07	71.48

水蒸气分压 /MPa	组合/%				产率/%	η/%
水蒸气分压 /MPa	CO₂	CO	H₂	CH₄	产率/%	η/%
0.32	43.36	4.33	49.97	2.35	56.64	68.48
0.40	43.89	3.75	50.93	1.43	56.10	67.48
0.48	44.24	3.10	51.66	1.00	55.76	67.35
0.56	44.25	2.61	52.30	0.84	55.74	67.34