HBr改性飞灰对Hg0的动态吸附及动力学模型

doi:10.16085/j.issn.1000-6613.2023-0325

摘要/Abstract

摘要：

为清晰描述HBr改性飞灰（HBr-FA）对Hg⁰吸附的全过程，基于固定床动态吸附实验，在同时考虑扩散和表面吸附氧化的条件下，建立了固定床中HBr-FA对Hg⁰的吸附动力学模型，讨论了Hg⁰吸附氧化过程的关键影响因素，探究了Hg⁰在扩散区域和表面活性位上的动力学行为。结果表明：该模型综合考虑了轴向返混、内外扩散和本征动力学过程，能够较好地拟合实验穿透曲线，并可求得相应的动力学参数，对气膜扩散系数更加敏感；初始Hg⁰浓度的提高可提供更高的能量克服扩散阻力，适当提高流量和床层厚度可减小外扩散阻力，进而表现出更优越的表观吸附氧化效果；该模型还可得到床层内和颗粒内（扩散和动力学区域）的Hg⁰浓度分布，发现在吸附初期，外扩散阻力对改性飞灰吸附氧化Hg⁰的过程影响更大。

关键词: HBr改性飞灰, 汞, 吸附氧化, 动力学, 外扩散, 固定床

Abstract:

In order to clearly describe the whole process of Hg⁰ adsorption by HBr-modified fly ash (HBr-FA), an adsorption kinetic model was established including diffusion and surface adsorption and oxidation based on the dynamic adsorption experiment on a fixed-bed column. The key influence factor of the adsorption and oxidation process of Hg⁰ was discussed, and the dynamic behavior of Hg⁰ in the diffusion region and surface active site was investigated. The model takes into account the processes of axial backmixing, internal and external diffusion, and intrinsic kinetics, which hence can fit well with the experimental breakthrough results with the corresponding kinetic parameters. The sensitivity analyses indicate that axial dispersion, gas film diffusion, and inner efficiency diffusion have dominant impacts on Hg⁰ adsorption, and the model is more sensitive to the gas film diffusivity. Furthermore, the increasing of initial Hg⁰ concentration is beneficial to decreasing the diffusion resistance and promoting the Hg⁰ adsorption-oxidation due to the improvement of mass transfer driving force. The external diffusion resistance can be reduced with the increase of inlet flow rate and bed thickness. In addition, the Hg⁰ concentration profiles inside the particle can be obtained from the model, which shows the external diffusion resistance has greater influence at the initial stage of Hg⁰ adsorption and oxidation by HBr-FA.

Key words: HBr-modified fly ash, mercury, adsorption and oxidation, kinetics, external diffusion, fixed-bed

中图分类号:

TQ028

顾永正, 张永生. HBr改性飞灰对Hg⁰的动态吸附及动力学模型[J]. 化工进展, 2023, 42(S1): 498-509.

GU Yongzheng, ZHANG Yongsheng. Dynamic behavior and kinetic model of Hg⁰ adsorption by HBr-modified fly ash[J]. Chemical Industry and Engineering Progress, 2023, 42(S1): 498-509.

图/表 20

图1 固定床实验系统示意图

表1 固定床动态吸附实验工况

工况	吸附剂质量m/mg	初始Hg⁰浓度C₀/μg·m^-3	入口流量Q/L·min^-1	床层厚度Z/mm
1	30	9.5	1	1.2
2	30	18.3	1	1.2
3	30	24	1	1.2
4	30	9.5	2	1.2
5	30	9.5	4	1.2
6	15	9.5	1	0.6
7	60	9.5	1	2.4

图2 固定床内HBr-FA吸附Hg0示意图

表2 HBr-FA物性参数

参数	HBr-FA
振实堆密度 $ρ B$ /kg·m^-3	0.85×10³
表观密度ρ_p/kg·m^-3	2.06×10³
真密度ρ_s/kg·m^-3	2.14×10³
床层空隙率ε_b	0.587
颗粒孔隙率ε	0.037
平均粒径R_p/m	1.61×10^-5
平均孔半径r_pore/cm	1.53×10^-6

表2 HBr-FA物性参数

参数	HBr-FA
振实堆密度 $ρ B$ /kg·m^-3	0.85×10³
表观密度ρ_p/kg·m^-3	2.06×10³
真密度ρ_s/kg·m^-3	2.14×10³
床层空隙率ε_b	0.587
颗粒孔隙率ε	0.037
平均粒径R_p/m	1.61×10^-5
平均孔半径r_pore/cm	1.53×10^-6

图3 不同初始Hg0浓度下得到的HBr-FA穿透曲线和模拟曲线

表3 根据不同入口Hg0浓度条件计算本征动力学方程中的动力学参数

动力学参数	数值
k₁/m³·(μg·s) ^-1	3.326×10^-4
q_m/μg·kg^-1	2.518×10⁵
K/m³·μg^-1	0.105

图4 初始Hg0浓度对Hg0吸附氧化速率的影响

表4 不同入口Hg0浓度下的扩散系数参数估计值

工况

初始Hg⁰浓度

/μg·m^-3

D_Z

/m²·s^-1

D_e

/m²·s^-1

k_g

/m·s^-1

图5 不同入口流量下得到的HBr-FA穿透曲线和模拟曲线

图6 入口流量对Hg0吸附氧化速率的影响

表5 不同入口流量下的扩散系数参数估计值

工况

入口流量

/L·min^-1

D_Z

/m²·s^-1

D_e

/m²·s^-1

k_g

/m·s^-1

图7 不同床层厚度下得到的HBr-FA穿透曲线和模拟曲线

图8 床层厚度对Hg0吸附氧化速率的影响

表6 不同床层厚度下扩散系数参数估计值

工况

床层厚度

/mm

D_Z

/m²·s^-1

D_e

/m²·s^-1

k_g

/m·s^-1

图9 轴向扩散系数DZ对穿透曲线的影响

图10 气膜扩散系数kg对穿透曲线的影响

图11 孔内有效扩散系数De对穿透曲线的影响

图12 床层内Hg0的浓度分布三维图（工况1）

图13 z/Z=0.05处HBr-FA颗粒内Hg0的浓度分布（工况1）

图14 16min时z/Z=0.05处HBr-FA颗粒内Hg0的浓度分布和表面平衡浓度分布(工况1)

参考文献 37

1	李晓航, 刘红刚, 路建洲, 等. 煤粉炉和循环流化床锅炉飞灰吸附汞动力学及其吸附机制[J]. 化工学报, 2019, 70(11): 4397-4409.
	LI Xiaohang, LIU Honggang, LU Jianzhou, et al. Kinetics and mechanism of mercury adsorption on fly ashes from pulverized coal boiler and circulating fluidized bed boiler[J]. CIESC Journal, 2019, 70(11): 4397-4409.
2	顾永正, 王树民. 改性燃煤飞灰吸附氧化脱汞机理研究进展[J]. 化工进展, 2017, 36(11): 4257-4264.
	GU Yongzheng, WANG Shumin. Research progress of mercury adsorption and oxidation mechanism on modified coal-fired fly ash[J]. Chemical Industry and Engineering Progress, 2017, 36(11): 4257-4264.
3	United Nations Environment Programme. Global mercury assessment 2018[R]. Chemicals and Health Branch Geneva, Switzerland: UNEP, 2019.
4	WANG Shumin. Near-zero air pollutant emission technologies and applications for clean coal-fired power[J]. Engineering, 2020, 6(12): 1408-1422.
5	中华人民共和国环境保护部. 《关于汞的水俣公约》生效公告[EB/OL]. (2017-08-16) [2023-02-15]. .
	Ministry of Environmental Protection of the People's Republic of China. Notice of entry into force of the Minamata convention on Mercury[EB/OL]. (2017-08-16) [2023-02-15]. .
6	WANG Shumin, ZHANG Yongsheng, GU Yongzheng, et al. Coupling of bromide and on-line mechanical modified fly ash for mercury removal at a 1000 MW coal-fired power plant[J]. Fuel, 2019, 247: 179-186.
7	ZHANG Yongsheng, MEI Dongqian, WANG Tao, et al. In-situ capture of mercury in coal-fired power plants using high surface energy fly ash[J]. Environmental Science & Technology, 2019, 53(13): 7913-7920.
8	KHUNPHONOI Rattabal, KHAMDAHSAG Pummarin, CHIARAKORN Siriluk, et al. Enhancement of elemental mercury adsorption by silver supported material[J]. Journal of Environmental Sciences, 2015, 32: 207-216.
9	张亮, 禚玉群, 杜雯, 等. 非碳基改性吸附剂汞脱除性能实验研究[J]. 中国电机工程学报, 2010, 30(17): 27-34.
	ZHANG Liang, ZHUO Yuqun, DU Wen, et al. Experimental study on mercury removal efficiencies of modified non-carbon sorbens[J]. Proceedings of the CSEE, 2010, 30(17): 27-34.
10	WANG Shumin, ZHANG Yongsheng, GU Yongzheng, et al. Using modified fly ash for mercury emissions control for coal-fired power plant applications in China[J].Fuel, 2016, 181(1): 1230-1237.
11	GU Yongzheng, ZHANG Yongsheng, LIN Jianwei, et al. Homogeneous mercury oxidation with bromine species released from HBr-modified fly ash[J]. Fuel, 2016, 169: 58-67.
12	LI Wenhan, SONG Na, ZHANG Yongsheng, et al. Mercury sorption properties of HBr-modified fly ash in a fixed bed reactor[J]. Journal of Thermal Analysis and Calorimetry, 2016, 124(1): 387-393.
13	SKODRAS G, DIAMANTOPOULOU Ir, PANTOLEONTOS G, et al. Kinetic studies of elemental mercury adsorption in activated carbon fixed bed reactor[J]. Journal of Hazardous Materials, 2008, 158(1): 1-13.
14	CAMARGO Carla Luciane Manske, DE RESENDE Neuman Solange, DE OLIVEIRA Amanda Gerhardt, et al. Investigation of adsorption-enhanced reaction process of mercury removal from simulated natural gas by mathematical modeling[J]. Fuel, 2014, 129: 129-137.
15	任建莉. 燃煤过程汞析出及模拟烟气中汞吸附脱除试验和机理研究[D]. 杭州: 浙江大学, 2003.
	REN Jianli. Experimental and theoretical study on mercury transformation and sorbents adsorption in simulated combustion flue gases[D]. Hangzhou: Zhejiang University, 2003.
16	王欣. 活性炭纤维低温吸附脱除汞的试验研究[D]. 武汉: 华中科技大学, 2006.
	WANG Xin. Experimental study on adsorption of mercury by activated carbon fibres at low temperature[D]. Wuhan: Huazhong University of Science and Technology, 2006.
17	FLORA Joseph R V, HARGIS Richard A, O’DOWD William J, et al. Modeling sorbent injection for mercury control in baghouse filters: I—Model development and sensitivity analysis[J]. Journal of the Air & Waste Management Association, 2003, 53(4): 478-488.
18	ZHONG Longchun, ZHANG Yongsheng, LIU Zhao, et al. Study of mercury adsorption by selected Chinese coal fly ashes[J]. Journal of Thermal Analysis and Calorimetry, 2014, 116(3): 1197-1203.
19	ZHANG Yongsheng, DUAN Wei, LIU Zhao, et al. Effects of modified fly ash on mercury adsorption ability in an entrained-flow reactor[J]. Fuel, 2014, 128: 274-280.
20	YANG Jianping, ZHAO Yongchun, GUO Xin, et al. Removal of elemental mercury from flue gas by recyclable CuCl₂ modified magnetospheres from fly ash. Part 4. Performance of sorbent injection in an entrained flow reactor system[J]. Fuel, 2018, 220: 403-411.
21	KARAKASI O K, MOUTSATSOU A. Surface modification of high calcium fly ash for its application in oil spill clean up[J]. Fuel, 2010, 89(12): 3966-3970.
22	XU Wenqing, WANG Hairui, ZHU Tingyu, et al. Mercury removal from coal combustion flue gas by modified fly ash[J]. Journal of Environmental Sciences, 2013, 25(2): 393-398.
23	DUNHAM Grant E, DEWALL Raymond A, SENIOR Constance L. Fixed-bed studies of the interactions between mercury and coal combustion fly ash[J]. Fuel Processing Technology, 2003, 82(2/3): 197-213.
24	翁惠新, 毛信军. 石油炼制过程反应动力学[M]. 北京: 烃加工出版社, 1987.
	WENG Huixin, MAO Xinjun. Reaction kinetics of petroleum refining process[M]. Beijing: Hydrocarbon Processing Press, 1987.
25	近藤精一, 石川达雄, 安部郁夫. 吸附科学[M]. 李国希, 译. 2版. 北京: 化学工业出版社, 2006.
	KONDO Seiichi, ISHIKAWA Tatsuo, Yuo ABE. Adsorption science[M]. LI Guoxi, trans. 2nd ed. Beijing: Chemical Industry Press, 2006.
26	王超. 燃煤细颗粒物及痕量元素排放控制特性的试验研究与现场测试[D]. 武汉: 华中科技大学, 2015.
	WANG Chao. Experimental study and field test on the emission and control of fine particulates and trace element from coal combustion[D]. Wuhan: Huazhong University of Science and Technology, 2015.
27	刘轩, 苏银皎, 滕阳, 等. 超低排放燃煤机组硒的迁移转化及飞灰对其富集特性[J]. 化工学报, 2022, 73(2): 923-932.
	LIU Xuan, SU Yinjiao, TENG Yang, et al. Selenium transformation in ultra-low-emission coal-fired power units and its enrichment characteristics in fly ash[J]. CIESC Journal, 2022, 73(2): 923-932.
28	XU Zhe, CAI Jianguo, PAN Bingcai. Mathematically modeling fixed-bed adsorption in aqueous systems[J]. Journal of Zhejiang University SCIENCE A, 2013, 14(3): 155-176.
29	CHUNG Sang Tae, KIM Kwang Il, YUN Yu ran. Adsorption of elemental mercury vapor by impregnated activated carbon from a commercial respirator cartridge[J]. Powder Technology, 2009, 192(1): 47-53.
30	Khosravi KOOCHEKSARAYI M, SHAMS K, LIU Y Z. Sorption dynamics in fixed-beds of inert core spherical adsorbents including axial dispersion and Langmuir isotherm[J]. AIChE Journal, 2009, 55(7): 1784-1792.
31	SATTERFIELD Charles N. Mass transfer in heterogeneous catalysis[M]. Cambridge, Mass.: M.I.T. Press, 1970.
32	SUN Ying, ZHU Jiawen, CHEN Kui, et al. Mass transfer mechanisms in fixed-bed adsorption of erythromycin[J]. Frontiers of Chemical Engineering in China, 2008, 2(4): 353-360.
33	SCHIESSER W E. The numerical method of lines: Integration of partial differential equations[M]. San Diego: Academic Press, 1991.
34	SCALA Fabrizio. Modeling mercury capture in coal-fired power plant flue gas[J]. Industrial & Engineering Chemistry Research, 2004, 43(10): 2575-2589.
35	ZHOU Wei, EGGENSPIELER Gilles, ROKANUZZAMAN Abu, et al. Prediction of activated carbon injection performance for mercury capture in a full-scale coal-fired boiler[J]. Industrial & Engineering Chemistry Research, 2010, 49(8): 3603-3610.
36	孔凡海, 赵俊武. 新型纳米吸附剂制备及脱除单质汞实验研究[J]. 热力发电, 2013, 42(11): 76-80.
	KONG Fanhai, ZHAO Junwu. Experimental study on elemental mercury adsorption by novel nano-sorbents[J]. Thermal Power Generation, 2013, 42(11): 76-80.
37	王海鸿, 刘应书, 李子宜, 等. 活性炭脱除SO₂吸附动力学模型及数值模拟[J]. 煤炭学报, 2015, 40(1): 203-211.
	WANG Haihong, LIU Yingshu, LI Ziyi, et al. Kinetic models and numerical simulation of SO₂ adsorption on activated carbon[J]. Journal of China Coal Society, 2015, 40(1): 203-211.

[1]	许家珩, 李永胜, 罗春欢, 苏庆泉. 甲醇水蒸气重整工艺的优化[J]. 化工进展, 2023, 42(S1): 41-46.
[2]	汪鹏, 张洋, 范兵强, 何登波, 申长帅, 张贺东, 郑诗礼, 邹兴. 高碳铬铁盐酸浸出过程工艺及动力学[J]. 化工进展, 2023, 42(S1): 510-517.
[3]	刘阳, 王云刚, 修浩然, 邹立, 白彦渊. 基于动力学分析的核桃壳最佳炭化工艺[J]. 化工进展, 2023, 42(S1): 94-103.
[4]	黄益平, 李婷, 郑龙云, 戚傲, 陈政霖, 史天昊, 张新宇, 郭凯, 胡猛, 倪泽雨, 刘辉, 夏苗, 主凯, 刘春江. 三级环流反应器中气液流动与传质规律[J]. 化工进展, 2023, 42(S1): 175-188.
[5]	董佳宇, 王斯民. 超声强化对二甲苯结晶特性及调控机理实验[J]. 化工进展, 2023, 42(9): 4504-4513.
[6]	程涛, 崔瑞利, 宋俊男, 张天琪, 张耘赫, 梁世杰, 朴实. 渣油加氢装置杂质沉积规律与压降升高机理分析[J]. 化工进展, 2023, 42(9): 4616-4627.
[7]	张婷婷, 潘大伟, 巨晓洁, 刘壮, 谢锐, 汪伟, 褚良银. Hg²⁺响应型智能凝胶检测光栅的构建与性能[J]. 化工进展, 2023, 42(8): 4143-4152.
[8]	陆洋, 周劲松, 周启昕, 王瑭, 刘壮, 李博昊, 周灵涛. CeO₂/TiO₂吸附剂煤气脱汞产物的浸出规律[J]. 化工进展, 2023, 42(7): 3875-3883.
[9]	王俊杰, 潘艳秋, 牛亚宾, 俞路. 分子水平催化重整装置模型构建及应用[J]. 化工进展, 2023, 42(7): 3404-3412.
[10]	赵毅, 杨臻, 张新为, 王刚, 杨旋. 不同裂缝损伤和愈合温度条件下沥青自愈合行为的分子模拟[J]. 化工进展, 2023, 42(6): 3147-3156.
[11]	曾天续, 张永显, 严渊, 刘宏, 马娇, 党鸿钟, 吴新波, 李维维, 陈永志. 羟胺对硝化菌活性及其动力学参数的影响[J]. 化工进展, 2023, 42(6): 3272-3280.
[12]	李瑞东, 黄辉, 同国虎, 王跃社. 原油精馏塔中铵盐吸湿特性及其腐蚀行为[J]. 化工进展, 2023, 42(6): 2809-2818.
[13]	庞楠炯, 王晓玲, 廖学品, 石碧. 胶原纤维固化黑荆树单宁对硼同位素的分离[J]. 化工进展, 2023, 42(5): 2616-2625.
[14]	张成松, 张静, 龚斌, 李明洋, 袁佳新, 李宏业. 自吸射流柔性搅拌桨振动特性[J]. 化工进展, 2023, 42(4): 1728-1738.
[15]	葛伟童, 廖亚龙, 李明原, 嵇广雄, 郗家俊. Pd-Fe/MWCNTs双金属催化剂制备及其脱氯动力学[J]. 化工进展, 2023, 42(4): 1885-1894.

HBr改性飞灰对Hg⁰的动态吸附及动力学模型

Dynamic behavior and kinetic model of Hg⁰ adsorption by HBr-modified fly ash

RichHTML

PDF (PC)

可视化

摘要/Abstract

引用本文

使用本文

图/表 20

参考文献 37

相关文章 15

编辑推荐

Metrics

本文评价