高温烟气中吸附剂捕集K的模型及其反应动力学研究

doi:10.11949/j.issn.0438-1157.20181497

摘要/Abstract

摘要：

针对生物质燃烧时采用吸附剂控制烟气中含K气体成分行为的性能描述，采用一维柱塞流反应器模型探究高岭土和煤灰捕集KOH（K₂CO₃）、KCl和K₂SO₄的性能及影响因素。通过模型计算与文献实验值比较检验模型合理性和确定动力学参数，并比较高岭土和煤灰捕集不同含K成分的性能差异。结果表明，采用表观动力学模型和单一的动力学参数可预测广泛反应条件下高岭土和煤灰捕集K的量，所确定的动力学参数是合理的；在给定的K浓度和烟气温度范围内，单位质量高岭土和煤灰捕集K的规律相似，均随烟气温度的升高而增大，随K浓度的增大而增大，且高岭土捕集能力受K浓度影响更明显；高岭土和煤灰捕集K的能力均为KOH强于KCl，强于K₂SO₄，且高岭土捕集能力明显强于煤灰。

关键词: 生物质燃烧, 含K成分控制, 吸附剂, 数学模型, 动力学

Abstract:

Aiming at the performance description of using adsorbent to control the behavior of K-containing gas in flue gas during biomass combustion, the performance and influencing factors of kaolin and coal fly ash trapping KOH (K₂CO₃), KCl and K₂SO₄ were investigated by one-dimensional plug flow reactor model. After comparing the model calculations with the experimental measurements in the literature to verify the rationality of the model and to determine the kinetic parameters, the differences in the performance of kaolin and coal fly ash adsorbing various K-containing gases were compared. The results showed that employing the global kinetic model and a single set of kinetic parameters was capable of predicting the amount of K captured by kaolin and coal fly ash under a wide range of reaction conditions and the kinetic parameters determined were reasonable. Within the given ranges of K concentration and flue gas temperature, the patterns of K capture by kaolin and coal fly ash were similar, both increasing with the increase of flue gas temperature and K concentration, but the effect of K concentration on kaolin adsorption was more obvious. The capabilities of K adsorption by both kaolin and coal fly ash were: KOH > KCl > K₂SO₄, but the adsorption capability of kaolin was much stronger than coal fly ash.

Key words: biomass combustion, K-containing species control, sorbent, mathematical model, kinetics

中图分类号:

TK 16

郑传杰, 盛昌栋. 高温烟气中吸附剂捕集K的模型及其反应动力学研究[J]. 化工学报, 2019, 70(6): 2259-2268.

Chuanjie ZHENG, Changdong SHENG. Modeling and reaction kinetics study on K capture by adsorbents in high temperature flue gas[J]. CIESC Journal, 2019, 70(6): 2259-2268.

图/表 9

表1 高岭土和煤灰吸附不同含K气体成分的反应动力学参数

Table 1 Kinetic parameters of kaolin and coal fly ash adsorbing different K-containing gas species

	高岭土				煤灰
	KOH	K₂CO₃	KCl	K₂SO₄	KOH	KCl	K₂SO₄
k ₀×10^－8/(m³ gas/((m³ pore)·s))	3.8	3.8	2.3	1.57	0.21	0.11	0.094
E/(kJ/mol)	25.08	25.08	25.08	25.08	25.08	25.08	25.08

图1 不同温度和KOH浓度下高岭土捕集KOH的模型计算与实验结果的比较

Fig.1 Comparison of model calculations and experimental measurements of KOH adsorption by kaolin at different temperatures and KOH concentrations

图2 不同KOH浓度下高岭土捕集K的模型计算与实验值比较（温度为1373 K，停留时间1.2 s）

Fig.2 Comparison of model calculated and experiment measured K capture by kaolin at different initial KOH concentrations (at temperature of 1373 K and residence time of 1.2 s)

图3 高岭土捕集K2CO3、KCl、K2SO4的模型计算与实验结果的比较

Fig.3 Comparison of model calculations and experiment measurements of K2CO3, KCl and K2SO4 adsorption by kaolin

表2 高岭土捕集K2CO3、KCl和K2SO4的模型计算条件

Table 2 Model calculating conditions for kaolin adsorbing K2CO3, KCl and K2SO4

含K成分	? _K×10⁶	烟气温度T/K	停留时间t/s
K₂CO₃	50	1373	1.2
	250	1373	1.2
	500	1073、1173、1373、1573	1.2
	750	1373	1.2
	1000	1373	1.2
KCl	50	1573	1.0
	250	1573	1.0
	500	1073、1173、1373、1573	1.2(1573 K时1.0)
	750	1573	1.0
	1000	1573	1.0
K₂SO₄	50	1373	1.2
	250	1373	1.2
	500	1073、1173、1373、1573	1.2
	750	1373	1.2

表3 煤灰物理化学特性[31]

Table 3 Physical and chemical properties of coal fly ash[31]

平均粒径/μm	BET表面积/(m²/g)	含量/%
平均粒径/μm	BET表面积/(m²/g)	SO₃	SiO₂	Al₂O₃	Fe₂O₃	CaO	MgO	Na₂O	K₂O	TiO₂	P₂O₅
10.2	8.04	0.52	37.98	42.61	6.68	5.08	1.31	0.59	1.69	1.18	2.36

图4 煤灰捕集KOH、KCl的模型计算与实验结果比较

Fig.4 Comparison of model calculations and experiment measurements of KOH and KCl adsorption by coal fly ash

图5 煤灰捕集K2SO4模型计算值与实验值比较(? K=5.0×10-4，停留时间1.2 s）

Fig.5 Comparison of model calculations and experiment measurements of K2SO4 adsorption by coal fly ash at ? K of 5.0×10-4 and residence time of 1.2 s

图6 高岭土、煤灰捕集KOH、KCl和K2SO4性能的比较

Fig.6 Comparison of performance of KOH, KCl and K2SO4 adsorption between kaolin and coal fly ash

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