Kinetics investigation on iron-based oxygen carrier aided oxy-fuel combustion of anthracite char

doi:10.11949/0438-1157.20210849

Abstract

Abstract:

Iron-based oxygen carrier aided oxy-fuel fluidized bed(FB) combustion replaces the traditional inert bed materials with oxygen carrier. The iron-based oxygen carrier expands the function of the “heat carrier” of the traditional bed material, and also assumes the role of the “oxygen carrier”, providing a new idea for adjusting the oxygen distribution in the furnace to match the coal combustion process. The combustion characteristics and kinetics of anthracite coal char and three types of iron-based oxygen carriers (pure Fe₂O₃, hematite, and steel slag) aided combustion of anthracite coal char were investigated in a thermogravimetric analyzer with the temperature range of 30℃ to 1100℃ at a heating of 10℃/min, 15℃/min and 20℃/min under a 10%O₂/90%CO₂ atmosphere. It is observed that the combustion behavior of anthracite coal char is much improved with the aid of the iron-based oxygen carriers, for instance, the combustion rate increases from 2.84%/min to 3.66%/min, 3.83%/min, 3.72%/min, the burnout temperature decreases from 878℃ to 803℃, 802℃, 810℃, and the comprehensive combustion index increases from 3×10^-8%²/(℃³?min²) to 6.39×10^-8%²/(℃³?min²), 6.21×10^-8%²/(℃³?min²), 6.08×10^-8%²/(℃³?min²) for pure Fe₂O₃, hematite and steel slag aided combustion, respectively. The results of kinetics analysis indicate that there is a compensation effect between the activation energy and the pre-exponential factor for the oxygen carriers aided combustion of anthracite coal char. Among three types of iron-based oxygen carriers, pure Fe₂O₃ is slightly better than hematite and steel slag in improving the combustion characteristics of anthracite coal char. Steel slag can be used as a bed material instead of quartz sand for iron-based oxygen carrier aided oxy-fuel fluidized bed combustion.

Key words: coal combustion, iron-based oxygen carrier, reaction kinetics, CO₂ capture, thermogravimetric analysis

摘要：

流化床铁基载氧体辅助富氧燃烧下传统石英砂床料被铁基载氧体替代，铁基载氧体扩展了传统床料的“热载体”的功能，另承担了“氧载体”的角色，为调节炉内氧分布与煤燃烧过程匹配提供了新思路。本文在热重实验平台探究了10%O₂/90%CO₂气氛下分析纯Fe₂O₃、赤铁矿及钢渣三种铁基载氧体辅助无烟煤焦燃烧特性及动力学。结果表明，相较于纯无烟煤焦燃烧，铁基载氧体辅助燃烧下无烟煤焦的燃烧特性得到显著改善，其中燃烧速率提高29%以上，燃尽温度降低65℃以上，综合燃烧指数提升2倍以上，活化能与指前因子同步增加且表现出“补偿效应”。三种铁基载氧体中分析纯Fe₂O₃对无烟煤焦燃烧特性的改善略优于赤铁矿和钢渣，钢渣可作为流化床铁基载氧体辅助富氧燃烧的床料替代石英砂。

关键词: 煤燃烧, 铁基载氧体, 反应动力学, 二氧化碳捕集, 热重分析

CLC Number:

TQ 534

Xu ZHAO, Changsheng BU, Xinye WANG, Xin ZHANG, Xiaolei CHENG, Naiji WANG, Guilin PIAO. Kinetics investigation on iron-based oxygen carrier aided oxy-fuel combustion of anthracite char[J]. CIESC Journal, 2022, 73(1): 384-392.

赵旭, 卜昌盛, 王昕晔, 张鑫, 程晓磊, 王乃继, 朴桂林. 铁基载氧体辅助无烟煤焦富氧燃烧动力学分析[J]. 化工学报, 2022, 73(1): 384-392.

Figures/Tables 14

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含量（工业分析）/%(mass, ad)					含量（元素分析）/%(mass, ad)
M	A	V	FC		C	H	O	N	S
1.12	35.01	9.63	54.24		55.26	2.4	4.16	0.83	1.22

含量（工业分析）/%(mass, ad)					含量（元素分析）/%(mass, ad)
M	A	V	FC		C	H	O	N	S
1.12	35.01	9.63	54.24		55.26	2.4	4.16	0.83	1.22

含量/%(mass)
SiO₂	Al₂O₃	Fe₂O₃	CaO	K₂O	MgO	Na₂O
52.41	32.91	4.5	3.87	1.76	0.53	0.15

含量/%(mass)
SiO₂	Al₂O₃	Fe₂O₃	CaO	K₂O	MgO	Na₂O
52.41	32.91	4.5	3.87	1.76	0.53	0.15

载氧体	含量/%(mass)
载氧体	Fe₂O₃	SiO₂	CaO	MgO	Al₂O₃	MnO	P₂O₅	TiO₂	其他
Fe₂O₃	99.9	―	―	―	―	―	―	―	0.1
赤铁矿	85.92	8.17	0.52	1.34	1.53	―	―	―	2.52
钢渣	27.76	13.51	36.15	9.44	3.78	4.76	1.64	1.18	1.78