电站锅炉尾部烟道补燃秸秆气化气的计算分析

Calculation and Analysis of Straw Gas Afterburning in the Tail Flue of Power Station Boiler

针对普遍存在的锅炉再热汽温偏低和SCR低负荷无法正常投运问题,提出一种锅炉耦合秸秆气化炉并在尾部烟道补燃燃气的技术方案。以某350 MW超临界锅炉为例,分别对在低温再热器入口补燃和SCR入口补燃进行热力计算和经济性分析,计算结果表明:100%负荷下,在尾部烟道低温再热器入口补燃9 900 m^3/h的气化气时,可将再热汽温升高13.5℃,降低供电煤耗1.2 g/(kW·h);50%负荷下,可将SCR入口烟温升高15.4℃,同时再热汽温升高32.9℃,降低供电煤耗5.7 g/(kW·h)。在SCR入口补燃1 360 m^3/h的秸秆气时,将SCR入口烟温升高8.7℃。该技术方案采用热一次风作为气化剂和助燃空气,并具有再燃还原NO等的技术优势。

To solve the common problems of reheat steam temperature on the low side and the failure operation of SCR under low load,a technical program of boiler coupling straw gasifier and gas afterburning in the tail flue is put forwared.With a 350 MW supercritical boiler,the thermodynamic calculation and economic analysis of the afterburning at the entrance of the low-temperature reheater and the afterburning at the entrance of SCR are performed.The results show that,at 100% load condition,with afterburning 9 900 m^3/h gas before the low temperature reheater,the reheater temperature temperature is increased by 13.5℃ and the power supply coal consumption is reduced by 1.2 g/(kW·h).At 50% load,the 15.4℃ increase in the entrance flue gas temperature of SCR,combined with the 32.9℃ increase in thereheat steam temperature can reduce the power supply coal consumption by 5.7 g/(kW·h).Afterburning 1 360 m^3/h of straw gas before SCR leads to 8.7℃ increase in the entrance flue gas temperature of SCR.This technical program use hot primary wind for gasification agent and combustion-supporting air.It also has many technical advantages,such as NO reduction by reburning of straw gas.