对冲燃烧锅炉掺烧污泥炉内燃烧及碱金属分布模拟研究

doi:10.3969/j.issn.2097-0706.2024.08.007

摘要/Abstract

摘要：

以某660 MW对冲燃煤锅炉为对象，采用数值模拟方法研究了掺烧干化污泥时炉内燃烧及碱金属分布情况，分析了掺烧位置、过量空气系数和污泥Cl含量对炉内燃烧及碱金属组分分布的影响。结果表明：掺烧污泥后，侧墙壁面区域碱金属质量浓度较高，采用中上层燃烧器层掺烧污泥可降低碱金属的排放速率和燃尽风燃烧器附近区域金属壁温；提高过量空气系数不仅可提高煤粉燃尽率，还可以降低侧墙贴壁区域碱金属质量浓度；降低污泥中Cl含量可有效降低烟气中的碱金属质量浓度和其他碱金属向NaCl的转化率。实际锅炉掺烧干化污泥时，建议采用中上层燃烧器掺烧，并适当降低过量空气系数以降低掺烧对炉内受热面的沾污、结渣和碱金属型高温腐蚀风险。

关键词: 电站锅炉, 污泥掺烧, 炉内燃烧, 碱金属, 数值模拟

Abstract:

Taking a 660 MW opposed firing boiler as the study object，the combustion features and distribution of alkali metals in the furnace during co-combustion with dehydrated sludge are studied by numerical simulation，and the influence factors including the blending layer， excess air coefficient and different Cl content in sludge are analyzed. The co-combustion with dehydrated sludge will increase the alkali metal mass concentration on the furnace side wall. The study indicates that blending sludge on the middle and upper layer of the burner can reduce the emission rate of alkali metals and lower the wall temperature near OFA nozzles. Increasing excess air coefficient can improve the burnout rate of pulverized coal and reduce the alkali metal mass concentration on the side wall. And decline of the Cl content in sludge can effectively reduce the concentration of alkali metals in flue gas and conversion rate of alkali metal compounds to NaCl. Blending sludges on the middle and upper layers of a co-combustion burner can reduce the excess air coefficient and alleviate the fouling， slagging and alkali metal high temperature corrosion in the furnace.

Key words: power station boiler, opposed firing boiler, co-combustion with sludge, in-furnace combustion, alkali metal, numerical simulation

中图分类号:

TK227.1

童家麟, 张岩, 刘文胜, 茅建波, 叶学民. 对冲燃烧锅炉掺烧污泥炉内燃烧及碱金属分布模拟研究[J]. 综合智慧能源, 2024, 46(8): 50-58.

TONG Jialin, ZHANG Yan, LIU Wensheng, MAO Jianbo, YE Xuemin. Numerical simulation on co-combustion and alkali metal distribution in an opposed firing boiler mixed with sludge[J]. Integrated Intelligent Energy, 2024, 46(8): 50-58.

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参考文献 24

[1]	李德波, 王明传, 杨新生, 等. Coats-Redfern模型和DAEM在污泥与煤掺烧过程中的动力学适应性分析[J]. 广东电力, 2019, 32(11):70-77.
	LI Debo, WANG Mingchuan, YANG Xinsheng, et al. Analysis on kinetic adaptability of Coast-Redfern model and DAEM in blending combustion of sludgeand coal[J]. Guangdong Electric Power, 2019, 32(11):70-77.
[2]	CHEN T, LEI C, YAN B, et al. Analysis of heavy metals fixation and associated energy consumption during sewage sludge combustion:Bench scale and pilot test[J]. Journal of Cleaner Production, 2019,229:1243-1250.
[3]	LIANG Y, XU D H, FENG P, et al. Municipal sewage sludge incineration and its air pollution control[J]. Journal of Cleaner Production, 2021, 295(3):126456.
[4]	WANG Y G, LIU Y, YANG W J, et al. Evaluation of combustion properties and pollutant emission characteristics of blends of sewage sludge and biomass[J]. Science of the Total Environment, 2020,720:137365.
[5]	MA M Y, LIANG Y, XU D H, et al. Gas emission characteristics of sewage sludge co-combustion with coal:Effect of oxygen atmosphere and feedstock mixing ratio[J]. Fuel, 2022, 322(12):124102.
[6]	ZHAO R D, QIN J G, CHEN T J, et al. Experimental study on co-combustion of low rank coal semicoke and oil sludge by TG-FTIR[J]. Waste Management, 2020,116:91-99.
[7]	VESILIND P A, RAMSEY T B. Effect of drying temperature on the fuel value of wastewater sludge[J]. Waste Management & Research, 1996, 14(2):189-196.
[8]	OGADA T, WERTHER J. Combustion characteristics of wet sludge in a fluidized bed:Release and combustion of the volatiles[J]. Fuel, 1996, 75(5):617-626.
[9]	LIU Y Q, CHENG L M, ZHAO Y G, et al. Transformation behavior of alkali metals in high-alkali coals[J]. Fuel Processing Technology, 2018,169:288-294.
[10]	曾宪鹏, 于敦喜, 于戈, 等. 准东煤燃烧中不同形态无机元素向颗粒物的转化行为[J]. 煤炭学报, 2019, 44(2):588-595.
	ZENG Xianpeng, YU Dunxi, YU Ge, et al. Transformation of inorganic elements in different forms into ash particles during Zhundong coal combustion[J]. Journal of China Coal Society, 2019, 44(2):588-595.
[11]	蒲旸, 刘洋, 傅培舫, 等. 基于火焰光谱的准东煤旋风燃烧过程中碱金属检测[J]. 洁净煤技术, 2022, 28(7): 81-87.
	PU Yang, LIU Yang, FU Peifang, et al. Research on alkali metal measurement during the cyclone combustion process of Zhundong coal based on flame spectrum[J]. Clean Coal Technology, 2022, 28(7):81-87.
[12]	WEI J J, WANG M, XU D L, et al. Migration and transformation of alkali/alkaline earth metal species during biomass and coal co-gasification:A review[J]. Fuel Processing Technology, 2022, 235(11):107376
[13]	WAN K D, XIA J, VERVISCH L, et al. Modelling alkali metal emissions in large-eddy simulation of a preheated pulverised-coal turbulent jet flame using tabulated chemistry[J]. Combustion Theory and Modelling, 2018, 22(2):203-236.
[14]	WANG C A, TANG G T, SUN R J, et al. The correlations of chemical property,alkali metal distribution,and fouling evaluation of Zhundong coal[J]. Journal of the Energy Institute, 2020, 93(6):2204-2214.
[15]	陈红, 周安鹂, 耿向瑾, 等. W火焰锅炉低负荷条件下掺烧煤泥的数值模拟[J]. 广东电力, 2018, 31(3):15-20.
	CHEN Hong, ZHOU Anli, GENG Xiangjin, et al. Numerical simulation on burning blended coal slime under the condition of low load in W-flame boiler[J]. Guangdong Electric Power, 2018, 31(3):15-20.
[16]	KUANG Y H, HE B S, WANG C J, et al. Numerical analyses of MILD and conventional combustions with the eddy dissipation concept (EDC)[J]. Energy, 2021,237:121622.
[17]	LIU Y Z, WANG Z H, WAN K D, et al. In situ measurements of the release characteristics and catalytic effects of different chemical forms of sodium during combustion of Zhundong coal[J]. Energy & Fuels, 2018, 32(6):6595-6602.
[18]	YU S H, ZHANG C, ZHANG X P, et al. Release and transformation characteristics of Na/Ca/S compounds of Zhundong coal during combustion/CO₂ gasification[J]. Journal of the Energy Institute, 2020, 93(2):752-765.
[19]	吕俊复, 史航, 吴玉新, 等. 燃用准东煤过程中碱/碱土金属迁移规律及锅炉结渣沾污研究进展[J]. 煤炭学报, 2020, 45(1):377-385.
	LÜ Junfu, SHI Hang, WU Yuxin, et al. Transformation of AAEM and ash deposition characteristics during combustion of Zhundong coal[J]. Journal of China Coal Society, 2020, 45(1):377-385.
[20]	郭啸峰, 魏小林, 李森. C/H/O/N/S/Cl/K/Na元素的详细化学反应机理的简化与验证[J]. 燃烧科学与技术, 2013, 19(1):21-30.
	GUO Xiaofeng, WEI Xiaolin, LI Sen. Reduction and verification of detailed reaction mechanism containing C/H/O/N/S/Cl/K/Na elements[J]. Journal of Combustion Science and Technology, 2013, 19(1):21-30.
[21]	江锋浩, 张守玉, 黄小河, 等. 高碱煤燃烧过程中结渣机理研究进展[J]. 煤炭转化, 2018, 41(2):1-8.
	JIANG Fenghao, ZHANG Shouyu, HUANG Xiaohe, et al. Research progress on slagging mechanism during high alkali coal combustion process[J]. Coal Conversion, 2018, 41(2):1-8.
[22]	GLARBORG P, MARSHALL P. Mechanism and modeling of the formation of gaseous alkali sulfates[J]. Combustion and Flame, 2005, 141(1-2):22-39.
[23]	季杰强. 高碱煤燃烧碱金属钠迁移特性研究[D]. 杭州: 浙江大学, 2019.
	JI Jieqiang. Migration characteristic of alkali metal sodium during high-alkali coal combustion[D]. Hangzhou: Zhejiang University, 2019.
[24]	DAYTON D C, BELLE-OUDRY D, NORDIN A. Effect of coal minerals on chlorine and alkali metals released during biomass/coal cofiring[J]. Energy & Fuels, 1999, 13(6):1203-1211.

项目	烟煤	干化污泥
w（C_ar)/%	58.60	19.63
w（H_ar)/%	3.33	3.32
w（O_ar)/%	7.28	11.19
w（N_ar)/%	0.79	3.21
w（S_ar)/%	0.63	0.70
w（A_ar)/%	19.77	41.95
w（M_t)/%	9.61	20.00
w（V_daf)/%	22.82	87.05
Q_ar.net/(MJ·kg^-1)	22.44	7.28
Q_d.net/(MJ·kg^-1)	24.50	9.73
w（Na_daf)/%	—	0.55
w（Cl_daf)/%	—	高Cl，0.45/低Cl，0.15

组分	烟煤	干化污泥
x(H₂)	57.084	88.150
x(CO)	26.778	11.850
x(CH₄)	26.138	0

反应方程	A	b	E(Cal·mol^-1)
Na⁺ + HCl → NaCl + H⁺	1.30×10¹⁵	0	9 990.0
NaCl + H⁺ → Na⁺ + HCl	1.10×10¹⁶	-0.5	4 557.1
NaOH + HCl → NaCl + H₂O	1.70×10¹⁴	0	0
NaCl + H₂O → NaOH + HCl	4.14×10¹²	0.6	32 161.8
NaO^- + HCl → NaCl + OH^-	1.30×10¹⁴	0	0
NaO^- + H₂O → NaOH + OH^-	1.30×10¹⁴	0	0
NaOH + OH^- → NaO^- + H₂O	2.23×10¹⁵	-0.4	-544.4
NaOH + H⁺ → Na⁺ + H₂O	5.00×10¹³	0	0
Na⁺ + H₂O → NaOH + H⁺	1.45×10¹¹	1.1	37 594.8

网格数/万	炉膛出口氧量/%	炉膛出口烟温/K	出口NO_x质量浓度/(mg·m^-3)
220	4.70	1 387	177
302	4.61	1 353	169
395	4.58	1 357	165

工况	掺烧位置	过量空气系数	污泥种类
1	C层燃烧器	1.2	高Cl污泥
2	D层燃烧器	1.2	高Cl污泥
3	E层燃烧器	1.2	高Cl污泥
4	D层燃烧器	1.1	高Cl污泥
5	D层燃烧器	1.3	高Cl污泥
6	D层燃烧器	1.2	低Cl污泥