Urea Induced Corrosion of 15CrMo Steel for Water Cooled Wall Tubes in Coal-fired Power Plants

doi:10.11902/1005.4537.2018.067

Journal of Chinese Society for Corrosion and protection

2019, Vol. 39

Issue (2): 114-122 DOI: 10.11902/1005.4537.2018.067

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Urea Induced Corrosion of 15CrMo Steel for Water Cooled Wall Tubes in Coal-fired Power Plants

Longbiao TIAN¹,Zhiping ZHU¹(

),Chunlei ZHANG²,Qiang YU¹,Lei YANG¹

1. School of Chemical and Biological Engineering, Changsha University of Science and Technology, Changsha 410014, China
2. Datang Central-China Electric Power Test Research Institute, Zhengzhou 450001, China

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Abstract

In order to figure out the corrosion problem of water cooled-wall tubes caused by urea in a coal-fired power plant, the corrosion behavior of 15CrMo steel at high temperature were studied in urea containing media with an autoclave aiming to simulate the operation situation of the power plant. The urea decomposition process and the corrosion of the steel were simultaneously examined at 270 ℃ in solutions with varying urea concentrations of 70, 140, 280, 560 and 840 mg/L, respectively. Peculiarly, during the decomposition process of the medium with urea concentration of 280 mg/L, the yield liquid- and vapor-phase were extracted from the reaction chamber at different time intervals for characterization with TOC analyzer and infrared spectrometer. Besides, the corrosion of 15CrMo steel in the yield urea solution were assessed by weight loss measurement, electrochemical impedance spectroscopy and polarization curve measurement. The surface morphology of the tested steel was characterized by SEM, EDS and XRD. Results show that urea produced corrosive ions NH₂COO^- during decomposition, which caused the corrosion of water wall tubes. The corrosion rate of 15CrMo steel increased with the increasing urea concentration, and the maximum corrosion rate was 0.593 mm/a. The urea leaked into water cooled wall tubes may be ascribed to certain consequences of improper design of the denitrification system, therefore, to eliminate such engineering errors can effectively prevent the occurrence of urea induced corrosion for water-cooled wall tubes.

Key words: urea water wall tube 15CrMo ammonium carbamate corrosion

Received: 18 May 2018

ZTFLH:

TG172.2

Fund: Supported by Hunan Provincial Science and Technology Plan Key Project(2013GK2016)

Corresponding Authors: Zhiping ZHU E-mail: zzp8389@163.com

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Cite this article:

Longbiao TIAN,Zhiping ZHU,Chunlei ZHANG,Qiang YU,Lei YANG. Urea Induced Corrosion of 15CrMo Steel for Water Cooled Wall Tubes in Coal-fired Power Plants. Journal of Chinese Society for Corrosion and protection, 2019, 39(2): 114-122.

URL:

https://www.jcscp.org/EN/10.11902/1005.4537.2018.067 OR https://www.jcscp.org/EN/Y2019/V39/I2/114

Fig.1 Experimental apparatus for urea decomposition

Fig.2 Contents of TOC in the vapor/liquid phases after decomposition of urea at 270 ℃ for 8 h

Fig.3 Concentrations of TOC in the vapor/liquid phases after decomposition of urea with the initial content of 280 mg/L at 270 ℃ for different time

Fig.4 IR spectra of 280 mg/L urea solution before and after decomposition at 270 ℃ for 8 h

Fig.5 Potentiodynamic polarization curves for 15CrMo steel in decomposition residues of urea solutions

Fig.6 Potentiodynamic polarization curves for 15CrMo steel in urea solutions with different concentrations

Table 1 Data of potentiodynamic polarization for 15CrMo steel in decomposition residues of urea solutions

Fig.7 Nyquist plots of 15CrMo steel in decomposition residues of urea solutions

Fig.8 Equivalent circuit model used to fit the impedance spectra of 15CrMo steel in decomposition residues of urea solutions

Table 3 Impedance parameters of 15CrMo steel in decomposition residues of urea solutions

Fig.9 Variation of corrosion rate determined by weight loss test for 15CrMo steel in urea solution at 270 ℃

Fig.10 Surface images of 15CrMo samples before (a) and after (b~f) corrosion in urea solution at 270 ℃

Fig.11 SEM image (a) and EDS result (b) of 15CrMo steel after immersed in 70 mg/L urea solution at 270 ℃ for 8 h

Fig.13 XRD pattern of 15CrMo steel after immersed in 140 mg/L urea solution at 270 ℃ for 8 h

Fig.12 SEM image (a) and EDS result (b) of 15CrMo steel after immersed in 140 mg/L urea solution at 270 ℃ for 8 h

[1]	Ministry of Environmental Protection. GB 13223-2011 Emission standard of air pollutants for thermal power plants [S]. Beijing: China Environmental Science Press, 2012
[1]	环境保护部. GB 13223-2011 火电厂大气污染物排放标准 [S]. 北京: 中国环境科学出版社, 2012
[2]	National Energy Administration. Upgrade and retrofit action plan of energy-saving and emission reduction for coal-fired power plants [R]. Beijing: National Energy Administration, 2014
[2]	国家能源局. 煤电节能减排升级与改造行动计划 (2014—2020年) [R]. 北京: 国家能源局, 2014
[3]	Pan D, Li S H, Jing Y H, et al. Study on fault diagnosis and operation optimization for power plant SCR with ultra-low emission [J]. Electr. Power, 2017, 50(3): 41
[3]	潘栋, 李淑宏, 景云辉等. 超低排放电站锅炉SCR脱硝装置的故障诊断及运行优化研究 [J]. 中国电力, 2017, 50(3): 41
[4]	Li D B, Zeng T H, Liao Y J, et al. Research on transformation scheme for full-load operation of SCR denitration system of 600 MW substation boiler and engineering practice [J]. Guangdong Electr. Power, 2016, 29(6): 12
[4]	李德波, 曾庭华, 廖永进等. 600MW电站锅炉SCR脱硝系统全负荷投运改造方案研究与工程实践 [J]. 广东电力, 2016, 29(6): 12
[5]	Koebel M, Elsener M, Madia G. Reaction pathways in the selective catalytic reduction process with NO and NO2 at low temperatures [J]. Ind. Eng. Chem. Res., 2001, 40: 52
[6]	Eichelbaum M, Farratuo R J, Castaldi M J. The impact of urea on the performance of metal exchanged zeolites for the selective catalytic reduction of NOx: Part I. Pyrolysis and hydrolysis of urea over zeolite catalysts [J]. Appl. Catal., 2010, 97B: 90
[7]	Zhang X Y, Zhang B, Lu X, et al. Experimental study on urea hydrolysis to ammonia for gas denitration in a continuous tank reactor [J]. Energy, 2017, 126: 677
[8]	Wang S D, Han P H, Ma R Y, et al. Effect of urea on condensates corrosion of stainless steels in simulated automotive exhaust environments [J]. J. Chin. Soc. Corros. Prot., 2013, 33: 41
[8]	王士栋, 韩沛洪, 马荣耀等. 尿素对模拟汽车废气环境中不锈钢冷凝液腐蚀行为的影响 [J]. 中国腐蚀与防护学报, 2013, 33: 41
[9]	Li Y Y, Feng J X. Selective non-catalytic reduction denitration in boiler applications [J]. Chem. Eng. Des. Commun., 2016, 42(4): 6
[9]	李英英, 冯俊香. 选择性非催化还原法脱硝技术的应用 [J]. 化工设计通讯, 2016, 42(4): 6
[10]	Sahu J N, Chava V S R K, Hussain S, et al. Optimization of ammonia production from urea in continuous process using ASPEN Plus and computational fluid dynamics study of the reactor used for hydrolysis process [J]. J. Ind. Eng. Chem., 2010, 16: 577
[11]	Todorova T, Peitz D, Kr?cher O, et al. Guanidinium formate decomposition on the (101) TiO2-Anatase surface: Combined minimum energy reaction pathway calculations and temperature-programmed decomposition experiments [J]. J. Phys. Chem., 2011, 115C: 1195
[12]	Zhang X Y, Zhang B, Lu X, et al. Crafts design and experimental study of urea hydrolysis to ammonia in thermal power plant [J]. Proc. CSEE, 2016, 36: 2452
[12]	张向宇, 张波, 陆续等. 火电厂尿素水解工艺设计及试验研究 [J]. 中国电机工程学报, 2016, 36: 2452
[13]	Meng L. Research on the urea catalytic hydrolysis technology for flue gas SCR denitrification of thermal power plant [J]. Electr. Power, 2016, 49: 157
[13]	(孟磊. 火电厂烟气SCR脱硝尿素催化水解制氨技术研究 [J]. 中国电力, 2016, 49: 157
[14]	Zhu G D. Study on corrosion and vibration of water-wall boiler on a 260 t/h power plant boiler [D]. Hangzhou: Zhejiang University, 2016
[14]	朱国栋. 260 t/h电站锅炉水冷壁腐蚀振动问题研究 [D]. 杭州: 浙江大学, 2016
[15]	Lu Z M, Ni J F, Zhang H, et al. Failure analysis on leakage of water-wall tube of a boiler using SNCR denitrification technique [J]. PTCA, 2014, 50: 907
[15]	卢忠铭, 倪进飞, 张辉等. 锅炉SNCR脱硝水冷壁管泄漏失效分析 [J]. 理化检验-物理分册, 2014, 50: 907
[16]	Shu Z P. 300 MW concurrent boiler denitration technology analysis [D]. Guangzhou: South China University of Technology, 2013
[16]	苏志鹏. 300 MW直流锅炉脱硝技术分析 [D]. 广州: 华南理工大学, 2013
[17]	Zhou G M, Zhao H J, Gong J Y, et al. Application of hybrid denitrification technology SNCR & SCR onto 410 t/h boiler [J]. Therm. Power Gener., 2011, 40(3): 58
[17]	周国民, 赵海军, 龚家猷等. SNCR/SCR联合脱硝技术在410t/h锅炉上的应用 [J]. 热力发电, 2011, 40(3): 58
[18]	Gu Y Y, Li E J, Cheng Y H. Research and discussion of SNCR denitration technology applied on 130t/h boiler [J]. Power Syst. Eng., 2015, 31(5): 75
[18]	顾杨杨, 李恩家, 程宇航. SNCR脱硝技术在130t/h煤粉炉上应用研究与探讨 [J]. 电站系统工程, 2015, 31(5): 75
[19]	Hu Z G, Zhang C, Yan Z Y. Research on corrosion of water-wall in SNCR denitrification and its countermeasures [J]. China New Technol. Prod., 2010, (2): 127
[19]	(胡振广, 张晨, 延宗昳. SNCR脱硝技术中水冷壁腐蚀问题的研究及对策 [J]. 中国新技术新产品, 2010, (2): 127)
[20]	Li X M, Jin Z, Liu W Z, et al. Effects of urea on corrosion behavior of Q235 steel in soil [J]. J. Chin. Soc. Corros. Prot., 2013, 33: 216
[20]	李喜明, 金哲, 刘五铸等. 尿素对土壤中Q235钢腐蚀的影响 [J]. 中国腐蚀与防护学报, 2013, 33: 216
[21]	Li X M, Zhang C Y, Zhu H, et al. Effect of urea on microbial corrosion behavior of Q235 steel in soil [J]. J. Chin. Soc. Corros. Prot., 2012, 32: 397
[21]	李喜明, 张春颜, 朱辉等. 土壤中残余尿素对Q235钢微生物腐蚀的影响 [J]. 中国腐蚀与防护学报, 2012, 32: 397
[22]	Zhang X Y, Gao N, Zhang B, et al. Experimental study on ammonia preparation by high concentration urea hydrolysis [J]. Therm. Power Gener., 2016, 45(6): 57
[22]	张向宇, 高宁, 张波等. 高浓度尿素水解制氨试验研究 [J]. 热力发电, 2016, 45(6): 57
[23]	Zhang B, Zhang X Y, Li M H, et al. Problem analysis for transportation of urea hydrolysis production gas for thermal power plants [J]. Therm. Power Gener., 2015, 44(11): 114
[23]	张波, 张向宇, 李明浩等. 火电厂尿素水解产品气输送问题分析 [J]. 热力发电, 2015, 44(11): 114
[24]	Song W M. Corrosion analysis of high-pressure pipelines in urea plant of CO2 gas-stripping process [J]. Corros. Prot. Petrochem. Ind., 2016, 33(2): 56
[24]	宋文明. CO2气提法尿素装置高压管线腐蚀原因分析 [J]. 石油化工腐蚀与防护, 2016, 33(2): 56
[25]	Zhou L X. Modest proposal for corrosion types and their influence factors in urea plant [J]. Chem. Fertil. Des., 2008, 46(3): 35
[25]	周留霞. 尿素装置的腐蚀类型及影响因素刍议 [J]. 化肥设计, 2008, 46(3): 35
[26]	Yao J T, Ji G H, Zhang X, et al. Analysis on mechanisms for deposition formation and block of ammonia transportation pipeline of SCR in Ultra Supercritical power plant [J]. Electr. Power Sci. Eng., 2016, 32(12): 12
[26]	姚建涛, 季广辉, 张欣等. 超临界机组SCR输氨管道堵塞原因分析及治理 [J]. 电力科学与工程, 2016, 32(12): 12
[27]	Zhang G Q, Zhang X J, Zhu T, et al. Formation mechanisms and block reason analysis for deposition in ammonia transportation pipeline of ammonia station in a power plant [J]. Therm. Power Gener., 2017, 46(1): 124
[27]	张贵泉, 张祥金, 朱涛等. 电厂氨站输氨管道内沉积物生成机理及堵塞原因分析 [J]. 热力发电, 2017, 46(1): 124
[28]	Wu X J, Ma H Y, Chen S H, et al. General equivalent circuits for faradaic electrode processes under electrochemical reaction control [J]. J. Electrochem. Soc., 1999, 146: 1847
[29]	Lebrini M, Robert F, Roos C. Inhibition effect of alkaloids extract from Annona squamosa plant on the corrosion of C38 steel in normal hydrochloric acid medium [J]. Int. J. Electrochem. Sci., 2010, 5: 1698
[30]	Roy P, Pal A, Sukul D. Origin of the synergistic effect between polysaccharide and thiourea towards adsorption and corrosion inhibition for mild steel in sulphuric acid [J]. RSC Adv., 2014, 4: 10607
[31]	Roy P, Karfa P, Adhikari U, et al. Corrosion inhibition of mild steel in acidic medium by polyacrylamide grafted Guar gum with various grafting percentage: Effect of intramolecular synergism [J]. Corros. Sci., 2014, 88: 246
[32]	Mahalik K, Sahu J N, Patwardhan A V, et al. Statistical modeling and optimization of hydrolysis of urea to generate ammonia for flue gas conditioning [J]. J. Hazard. Mater., 2010, 182: 603
[33]	Qin F, Wang S J, Kim I, et al. Heat of absorption of CO2 in aqueous ammonia and ammonium carbonate/carbamate solutions [J]. Int. J. Greenh. Gas Con., 2011, 5: 405
[34]	Watanabe H, Yamazaki H, Wang X Y, et al. Oxygen and hydrogen peroxide reduction catalyses in neutral aqueous media using copper ion loaded glassy carbon electrode electrolyzed in ammonium carbamate solution [J]. Electrochim. Acta, 2009, 54: 1362
[35]	Li M J. Analysis on equipment corrosion and its measures against it in urea plant [J]. Mod. Chem. Ind., 2006, 26(11): 54
[35]	李民杰. 尿素设备腐蚀的影响因素分析及防腐措施 [J]. 现代化工, 2006, 26(11): 54
[36]	Ren Z M, Bai X C, Huang J B, et al. Analysis and treatment of blockage in denitrification ammonia zone of Daihai power plant [J]. Inform. Constr., 2015, (10): 202
[36]	(任治民, 白秀春, 黄静波等. 岱海电厂脱硝氨区系统堵塞原因分析及处理 [J]. 信息化建设, 2015, (10): 202)
[37]	Zhu Z P, Xiong S H, Zhao Y F, et al. Pitting corrosion characteristics of boiler water-wall tubes influenced by 20G and 15CrMo materials in Cl- solution [J]. Proc. CSEE, 2012, 32(2): 67
[37]	朱志平, 熊书华, 赵永福等. 锅炉水冷壁管材料20G和15CrMo在含Cl--溶液中的点蚀特性 [J]. 中国电机工程学报, 2012, 32(2): 67
[38]	Huang J Y, Yang Z, Lu J T, et al. Failure analysis of flange used for urea hydrolysis equipment [J]. Therm. Power Gener., 2016, 45(6): 111
[38]	黄锦阳, 杨征, 鲁金涛等. 尿素水解制氨装置法兰失效原因分析 [J]. 热力发电, 2016, 45(6): 111

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