SCR烟气脱硝尿素热解和水解技术经济性分析
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摘要
尿素由于运输储存安全方便和对环境无害的特点,成为燃煤电厂SCR烟气脱硝还原剂液氨的可靠替代品。选择合适的尿素制氨技术是SCR烟气脱硝液氨改尿素工程的关键环节。通过工程建模对比分析采用尿素热解和尿素水解工艺的投资费用和运行成本,采用热力学方法分析尿素制氨系统能耗水平。结果表明:尿素水解投资略高于尿素热解,但其运行成本较低,技术经济性更优;尿素热解运行成本高的原因主要在于尿素转化率偏低,且采用高品质电能作为热源。
Because of its safety and convenience for transportation and storage in addition to its harmlessness to environment, urea has become a reliable substitute for liquid ammonia, a reducing agent for SCR flue gas denitrification in coal-fired power plants. The key part of the project to switch to urea from liquid ammonia is how to select suitable urea technology. In this paper, the investment cost and operation cost of urea pyrolysis process and urea hydrolysis process are analyzed through engineering modeling. The energy consumption level of urea ammonia production system is also studied by using thermodynamic method. The results show that the cost of urea hydrolysis is slightly higher than that of urea pyrolysis, but the operation cost is lower and the technical economy performance is better. The main reason for the high operation cost of urea pyrolysis is found out to be the low conversion rate of urea and the application of high quality electric energy as heat source.
Because of its safety and convenience for transportation and storage in addition to its harmlessness to environment, urea has become a reliable substitute for liquid ammonia, a reducing agent for SCR flue gas denitrification in coal-fired power plants. The key part of the project to switch to urea from liquid ammonia is how to select suitable urea technology. In this paper, the investment cost and operation cost of urea pyrolysis process and urea hydrolysis process are analyzed through engineering modeling. The energy consumption level of urea ammonia production system is also studied by using thermodynamic method. The results show that the cost of urea hydrolysis is slightly higher than that of urea pyrolysis, but the operation cost is lower and the technical economy performance is better. The main reason for the high operation cost of urea pyrolysis is found out to be the low conversion rate of urea and the application of high quality electric energy as heat source.
引文
[1]解永刚,程慧.火电厂SCR脱硝还原剂的选择与比较[J].电力科技与环保, 2010, 26(5):32–33.XIE Yonggang, CHENG Hui. Selection and comparison of reducing agent on SCR DeNOxsystem in thermal power plants[J]. Electric Power Technology and Environmental Protection, 2010, 26(5):32–33.
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[3]吕洪坤,杨卫娟,周志军,等.选择性非催化还原法在电站锅炉上的应用[J].中国电机工程学报, 2008, 28(23):14–19.LV Hongkun, YANG Weijuan, ZHOU Zhijun, et al. Application of selective non-catalytic reduction on a power plant boiler[J].Proceedings of the CSEE, 2008, 28(23):14–19.
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[5]陈镇超,杨卫娟,周俊虎,等.尿素催化水解特性试验研究[J].中国电机工程学报, 2011, 31(35):41–46.CHEN Zhenchao, YANG Weijuan, ZHOU Junhu, et al. Experimental investigation on the properties of urea thermohydrolysis with catalysts[J]. Proceedings of the CSEE, 2011, 31(35):41–46.
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[7]赵冬贤,刘绍培,吴晓峰,等.尿素热解制氨技术在SCR脱硝中的应用[J].热力发电, 2009, 38(8):65–67.ZHAO Dongxian, LIU Shaopei, WU Xiaofeng, et al. Application of urea pyrolysis to prepare ammonia technology into SCR denitrification[J]. Thermal Power Generation, 2009, 38(8):65–67.
[8]惠润堂,韦飞,闫世平,等.国产首套尿素水解装置在大型火电厂的工业化应用及技术优化[J].中国电力, 2014, 47(7):150–155.HUI Runtang, WEI Fei, YAN Shiping,et al. The industrial application and technical optimization of first domestically-made urea hydrolysis unit in large power plants[J]. Electric Power, 2014,47(7):150–155.
[9]郑伟,甄志,黄波,等.烟气脱硝还原剂制备工艺[J].热力发电,2013, 42(2):103–105.ZHENG Wei, ZHEN Zhi, HUANG Bo, et al. Preparation process of reductant for flue gas denitrification[J]. Thermal Power Generation,2013, 42(2):103–105.
[10]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(1):157–160.MENG Lei. Research on the urea catalytic hydrolysis technology for flue gas SCR denitrification of thermal power plant[J]. Electric Power, 2016, 49(1):157–160.
[11]SAHU J N, GANGADHARAN P, PATWARDHAN A V,et al.Catalytic hydrolysis of urea with fly ash for generation fo ammonia in a batch reactor for flue gas conditioning and NOxreduction[J].Industrial&Engineering Chemistry Research, 2009, 48(2):727–734.
[12]MAHALIK K, SAHU J N, PATWARDHAN A V,et al. Kinetic studies on hydrolysis of urea in a semi-batch reactor at atmospheric pressure for safe use of ammonia in a power plant for flue gas conditioning[J].Journal of Hazardous Materials, 2010, 175(1):629–637.
[13]姚宣,沈滨,郑鹏,等.烟气脱硝用尿素水解装置性能分析[J].中国电机工程学报, 2013, 33(14):38–43.YAO Xuan, SHEN Bin, ZHENG Peng, et al. Characteristics of urea hydrolysis equipment for flue gas denitration[J]. Proceedings of the CSEE, 2013, 33(14):38–43.
[14]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(9):2452–2458.ZHANG Xiangyu, ZHANG Bo, LU Xu,et al. Crafts design and experimental study of urea hydrolysis to ammonia in thermal power plant[J]. Proceedings of the CSEE, 2016, 36(9):2452–2458.
[15]中国石化集团上海工程有限公司.化工工艺设计手册[M].北京:化学工业出版社, 2009.
[16]FANG H L, DACOSTA H F. Urea thermolysis and NOx reduction with and without SCR catalysts[J].Applied Catalysis B(Environmental), 2003, 46(1):17–34.
[17]SCHABER P M, COLSON J, HIGGINS S,et al. Thermal decomposition(pyrolysis)of urea in an open reaction vessel[J].Thermochimica Acta, 2004, 424(1):131–142.
[18]喻小伟,李宇春,蒋娅,等.尿素热解研究及其在脱硝中的应用[J].热力发电, 2012, 41(1):1–5.YU Xiaowei, LI Yuchun, JIANG Ya,et al. Study on pyrolysis of urea and its application in denitrifcation[J]. Thermal Power Generation, 2012, 41(1):1–5.
[19]叶茂,杨志忠,晏顺娟,等. SCR烟气脱硝尿素热解用炉内气气换热器技术研究[J].东方电气评论, 2015, 29(2):76–82.YE Mao, YANG Zhizhong, YAN Shunjuan, et al. Research on the flue gas-air heat exchanger of urea pyrogenation for SCR flue gas De-NOxtechnology[J]. Dongfang Electric Review, 2015, 29(2):76 –82.
[20]徐威. SCR烟气脱硝尿素热解炉前烟气加热器技术研究[J].中国电力, 2017, 50(1):177–180.XU Wei. Research on flue gas heater for urea pyrolysis of SCR flue gas De-NOx system[J]. Electric Power, 2017, 50(1):177–180.
[2]杜振,钱徐悦,何胜,等.燃煤电厂烟气SCR脱硝成本分析与优化[J].中国电力, 2013, 46(10):124–128.DU Zhen, QIAN Xuyue, HE Sheng, et al. Analysis and optimization for operating costs of gas SCR DeNOx in coal-fired power plants[J].Electric Power, 2013, 46(10):124–128.
[3]吕洪坤,杨卫娟,周志军,等.选择性非催化还原法在电站锅炉上的应用[J].中国电机工程学报, 2008, 28(23):14–19.LV Hongkun, YANG Weijuan, ZHOU Zhijun, et al. Application of selective non-catalytic reduction on a power plant boiler[J].Proceedings of the CSEE, 2008, 28(23):14–19.
[4]王福伟,王倩,刘晓明,等.脱硝供氨系统中尿素制氨技术探讨[J].现代化工, 2011, 31(3):63–65, 67.WANG Fuwei, WANG Qian, LIU Xiaoming,et al. Technical research on ammonia preparation from urea for denitrification[J].Modern Chemical Industry, 2011, 31(3):63–65, 67.
[5]陈镇超,杨卫娟,周俊虎,等.尿素催化水解特性试验研究[J].中国电机工程学报, 2011, 31(35):41–46.CHEN Zhenchao, YANG Weijuan, ZHOU Junhu, et al. Experimental investigation on the properties of urea thermohydrolysis with catalysts[J]. Proceedings of the CSEE, 2011, 31(35):41–46.
[6]张强.燃煤电站SCR烟气脱硝技术及工程应用[M].北京:化学工业出版社, 2007.
[7]赵冬贤,刘绍培,吴晓峰,等.尿素热解制氨技术在SCR脱硝中的应用[J].热力发电, 2009, 38(8):65–67.ZHAO Dongxian, LIU Shaopei, WU Xiaofeng, et al. Application of urea pyrolysis to prepare ammonia technology into SCR denitrification[J]. Thermal Power Generation, 2009, 38(8):65–67.
[8]惠润堂,韦飞,闫世平,等.国产首套尿素水解装置在大型火电厂的工业化应用及技术优化[J].中国电力, 2014, 47(7):150–155.HUI Runtang, WEI Fei, YAN Shiping,et al. The industrial application and technical optimization of first domestically-made urea hydrolysis unit in large power plants[J]. Electric Power, 2014,47(7):150–155.
[9]郑伟,甄志,黄波,等.烟气脱硝还原剂制备工艺[J].热力发电,2013, 42(2):103–105.ZHENG Wei, ZHEN Zhi, HUANG Bo, et al. Preparation process of reductant for flue gas denitrification[J]. Thermal Power Generation,2013, 42(2):103–105.
[10]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(1):157–160.MENG Lei. Research on the urea catalytic hydrolysis technology for flue gas SCR denitrification of thermal power plant[J]. Electric Power, 2016, 49(1):157–160.
[11]SAHU J N, GANGADHARAN P, PATWARDHAN A V,et al.Catalytic hydrolysis of urea with fly ash for generation fo ammonia in a batch reactor for flue gas conditioning and NOxreduction[J].Industrial&Engineering Chemistry Research, 2009, 48(2):727–734.
[12]MAHALIK K, SAHU J N, PATWARDHAN A V,et al. Kinetic studies on hydrolysis of urea in a semi-batch reactor at atmospheric pressure for safe use of ammonia in a power plant for flue gas conditioning[J].Journal of Hazardous Materials, 2010, 175(1):629–637.
[13]姚宣,沈滨,郑鹏,等.烟气脱硝用尿素水解装置性能分析[J].中国电机工程学报, 2013, 33(14):38–43.YAO Xuan, SHEN Bin, ZHENG Peng, et al. Characteristics of urea hydrolysis equipment for flue gas denitration[J]. Proceedings of the CSEE, 2013, 33(14):38–43.
[14]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(9):2452–2458.ZHANG Xiangyu, ZHANG Bo, LU Xu,et al. Crafts design and experimental study of urea hydrolysis to ammonia in thermal power plant[J]. Proceedings of the CSEE, 2016, 36(9):2452–2458.
[15]中国石化集团上海工程有限公司.化工工艺设计手册[M].北京:化学工业出版社, 2009.
[16]FANG H L, DACOSTA H F. Urea thermolysis and NOx reduction with and without SCR catalysts[J].Applied Catalysis B(Environmental), 2003, 46(1):17–34.
[17]SCHABER P M, COLSON J, HIGGINS S,et al. Thermal decomposition(pyrolysis)of urea in an open reaction vessel[J].Thermochimica Acta, 2004, 424(1):131–142.
[18]喻小伟,李宇春,蒋娅,等.尿素热解研究及其在脱硝中的应用[J].热力发电, 2012, 41(1):1–5.YU Xiaowei, LI Yuchun, JIANG Ya,et al. Study on pyrolysis of urea and its application in denitrifcation[J]. Thermal Power Generation, 2012, 41(1):1–5.
[19]叶茂,杨志忠,晏顺娟,等. SCR烟气脱硝尿素热解用炉内气气换热器技术研究[J].东方电气评论, 2015, 29(2):76–82.YE Mao, YANG Zhizhong, YAN Shunjuan, et al. Research on the flue gas-air heat exchanger of urea pyrogenation for SCR flue gas De-NOxtechnology[J]. Dongfang Electric Review, 2015, 29(2):76 –82.
[20]徐威. SCR烟气脱硝尿素热解炉前烟气加热器技术研究[J].中国电力, 2017, 50(1):177–180.XU Wei. Research on flue gas heater for urea pyrolysis of SCR flue gas De-NOx system[J]. Electric Power, 2017, 50(1):177–180.