燃煤机组耦合氨燃料燃烧特性及经济性探讨

Discussion on coal-fired units coupled with ammonia fuel:combustion characteristics and economy

氨作为无碳燃料在燃煤机组上耦合燃烧可实现减污降碳,对助力我国“双碳”目标的实现具有重要意义。调研了氨作为替代燃料的优劣势、燃煤机组耦合氨的燃烧特性及相关研究的最新进展,认为在掺氨比例小于20%(热量比值,下同)时,采用合适的流速与方式将氨射入炉内相对低O_(2)浓度、高NO_(x)浓度区域,对炉内燃烧稳定性、炉膛出口NO_(x)浓度与飞灰含碳量等燃烧特性的影响较小。针对某330 MW燃煤机组耦合氨燃烧开展碳排放强度和热力性能的计算,并结合“绿氨”生产成本对2种碳减排方式做经济性分析,结果表明:该机组掺氨后锅炉排烟温度有所降低,锅炉热效率略有提高;在掺氨20%时该机组年碳减排量约26.73万t,碳排放强度为719.90 g/(kW·h);在20%碳减排幅度下,考虑煤价浮动,当制“绿氨”电价低于0.10~0.18元/(kW·h)时,该机组掺氨较碳捕集与封存具有经济性优势。相关结论可为燃煤机组掺氨燃烧的研究及实践提供参考。

As a carbon free fuel,ammonia coupled combustion on coal-fired units can achieve pollution reduction and carbon reduction,which is of great significance to helpingachieve the“double carbon”targetin China.The advantages and disadvantages of ammonia as an alternative fuel,coupled ammonia combustion characteristics of coal-fired units and the latest progress in related research were investigated.It is believed that when the ammonia mixing ratio is less than 20%,the appropriate flow rate and way should be adopted to inject ammonia into thefurnace area withrelatively low cocentration of O_(2) and highconcentration of NO_(x),which has little influence on combustion performance,such as combustion stability,NO_(x) concentration and carbon content of fly ash.The carbon emission intensity and thermal performance of coupled ammonia combustion of a 330 MW coal-fired unit were calculated,and economic analysis on the two carbon emission reduction methods was carried outbased on the production cost of“green ammonia”.The results show that,the boiler exhaust temperature decreases and the boiler thermal efficiency increases slightly after adding ammonia.When the ammonia mixing ratiois 20%,the annual carbon emission reduction of the unit is about 267300 t,and the carbon emission intensity is 719.90 g/(kW·h).Under the range of 20% carbon emission reduction and considering the fluctuation of coal price,when the electricity price of“green ammonia”is lower than 0.10~0.18 yuan/(kW·h),ammonia blendinghas economic advantages compared withcarbon capture and storage.Relevant conclusions can provide reference for the research and practice of ammonia mixing in coal-fired units.