集成超临界CO_2循环的燃煤发电系统冷端优化
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摘要
为了降低超临界燃煤电站抽汽侧较大的过热度及解决烟气与空气换热温差不匹配的问题,进一步提高机组效率,以某典型1 000 MW超临界燃煤电站为例,提出了耦合超临界CO_2循环的燃煤发电系统,利用过热蒸汽加热CO_2驱动超临界CO_2循环,使过热度显著降低,并将锅炉尾部烟道中空气预热器分为两级,两级间布置低温省煤器,加热高参数给水及凝结水,分析了集成系统的节能效果。结果表明:烟气温度降低至100.0℃时,集成系统较案例电站与常规余热系统的总出功分别提高了30.07 MW和25.51 MW,供电煤耗分别降低了7.9 g/(kW·h)和6.7 g/(kW·h),节能效果显著。
To reduce the high degree of superheat of the steam bleed and the large heat-transfer temperature difference to achieve high power generation efficiency of ultra supercritical coal-fired power units, an improved conceptual supercritical coal-fired power generation design was proposed, which integrates a supercritical CO_2(S-CO_2) power cycle to utilize the superheat of steam bleeds to heat the CO_2 medium and drive the CO_2 cycle, thus reducing the degree of superheat significantly; whereas the air preheating process in boiler tail flue is divided into two stages, between which a low temperature economizer is allocated to heat the high-temperature feedwater and condensate. The energy-saving effects of the proposed system were analyzed based on a typical 1 000 MW supercritical power unit. Results show that, compared with the reference power unit and a conventional flue gas waste heat recovery system, the additional electric power output of the proposed system has been increased by 30.07 MW and 25.51 MW, respectively. Moreover, the power supply coal consumption has been reduced by 7.9 g/(kW·h) and 6.7 g/(kW·h), respectively, indicating significant energy-saving effects.
To reduce the high degree of superheat of the steam bleed and the large heat-transfer temperature difference to achieve high power generation efficiency of ultra supercritical coal-fired power units, an improved conceptual supercritical coal-fired power generation design was proposed, which integrates a supercritical CO_2(S-CO_2) power cycle to utilize the superheat of steam bleeds to heat the CO_2 medium and drive the CO_2 cycle, thus reducing the degree of superheat significantly; whereas the air preheating process in boiler tail flue is divided into two stages, between which a low temperature economizer is allocated to heat the high-temperature feedwater and condensate. The energy-saving effects of the proposed system were analyzed based on a typical 1 000 MW supercritical power unit. Results show that, compared with the reference power unit and a conventional flue gas waste heat recovery system, the additional electric power output of the proposed system has been increased by 30.07 MW and 25.51 MW, respectively. Moreover, the power supply coal consumption has been reduced by 7.9 g/(kW·h) and 6.7 g/(kW·h), respectively, indicating significant energy-saving effects.
引文
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[2] XU Cheng,BAI Pu,XIN Tuantuan,et al.A novel solar energy integrated low-rank coal fired power generation using coal pre-drying and an absorption heat pump[J].Applied Energy,2017,200:170-179.
[3] 刘颖华,郜宁,周璐瑶,等.超超临界机组回热抽汽过热度的优化利用[J].电站系统工程,2015,31(4):16-18,25.LIU Yinghua,GAO Ning,ZHOU Luyao,et al.Optimized utilization of superheat of extraction in ultra-supercritical units[J].Power System Engineering,2015,31(4):16-18,25.
[4] 周璐瑶,徐钢,白璞,等.1 000 MW超超临界机组回热抽汽过热度多种利用形式的热力学分析[J].动力工程学报,2017,37(6):495-500,512.ZHOU Luyao,XU Gang,BAI Pu,et al.Thermodynamic analysis on the superheating degree utilization modes of 1 000 MW ultra-supercritical units[J].Journal of Chinese Society of Power Engineering,2017,37(6):495-500,512.
[5] 徐钢,许诚,杨勇平,等.电站锅炉余热深度利用及尾部受热面综合优化[J].中国电机工程学报,2013,33(14):1-8.XU Gang,XU Cheng,YANG Yongping,et al.Deep utilization of exhaust heat and comprehensive optimization of tail heating surfaces for utility boilers[J].Proceedings of the CSEE,2013,33(14):1-8.
[6] 马有福,杨丽娟,吕俊复.电站锅炉尾部烟气余热利用系统技术经济性比较[J].动力工程学报,2017,37(4):321-328.MA Youfu,YANG Lijuan,Lü Junfu.Techno-economic comparison of three processes for boiler waste heat recovery[J].Journal of Chinese Society of Power Engineering,2017,37(4):321-328.
[7] 宋景慧,阚伟民,许诚,等.电站锅炉烟气余热利用与空气预热器综合优化[J].动力工程学报,2014,34(2):140-146.SONG Jinghui,KAN Weimin,XU Cheng,et al.Comprehensive optimization of air preheater for boiler flue gas heat recovery[J].Journal of Chinese Society of Power Engineering,2014,34(2):140-146.
[8] AHN Y,BAE S J,KIM M,et al.Review of supercritical CO2 power cycle technology and current status of research and development[J].Nuclear Engineering and Technology,2015,47(6):647-661.
[9] 刘明,张旭伟,王朝阳,等.集成SCO2动力循环的燃煤电站余热回收系统研究[J].工程热物理学报,2017,38(8):1613-1618.LIU Ming,ZHANG Xuwei,WANG Chaoyang,et al.Study on heat recovery system of coal-fired power plant integrated with SCO2 power cycle[J].Journal of Engineering Thermophysics,2017,38(8):1613-1618.
[10] BAI Ziwei,ZHANG Guoqiang,LI Yongyi,et al.A supercritical CO2 Brayton cycle with a bleeding anabranch used in coal-fired power plants[J].Energy,2018,142:731-738.
[11] MECHERI M,le MOULLEC Y.Supercritical CO2 Brayton cycles for coal-fired power plants[J].Energy,2016,103:758-771.
[12] XU Cheng,ZHANG Qiang,YANG Zhiping,et al.An improved supercritical coal-fired power generation system incorporating a supplementary supercritical CO2 cycle[J].Applied Energy,2018,231:1319-1329.
[13] ISHIDA M,KAWAMURA K.Energy and exergyanalysis of a chemical process system with distributed parameters based on the enthalpy-direction factor diagram[J].Industrial & Engineering and Chemistry Process Design and Development,1982,21(4):690-695.
[14] JIN Hongguang,ISHIDA M.Graphical exergy analysis of complex cycles[J].Energy,1993,18(6):615-625.
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