锅炉启机过程中飞灰再燃及爆炸风险特性研究

Study on fly ashreburning and explosion risk characteristics during boiler startup

针对燃煤电厂锅炉启机过程中高温烟气与锅炉尾部烟道内未燃尽飞灰和烃类相遇而引起二次燃烧或爆炸现象,开展了相关研究。首先对锅炉启机烟气及飞灰可燃成分进行了分析,发现烟气可燃成分约为0.1%~0.3%,飞灰碳含量为12.04%~44.66%、挥发分含量为3.71%~13.20%;其次对采集飞灰燃烧特性进行了研究,分别以10、20、30℃/min的升温速率从室温升到1000℃,发现飞灰着火温度随升温速率提高而上升,因此适当提高升温速率,飞灰更不易着火;最后通过分析高低温烟气混合温度、飞灰爆炸下限浓度和爆炸极限氧浓度,发现SCR入口烟温可达到364℃,飞灰浓度小于50 g/m^(3),证明锅炉启机过程中尾部管道内的飞灰不易爆炸,确保SCR系统可以有效安全工作。

In order to avoid the risk of secondary combustion and explosion when high-temperature flue gas met with unburned fly ash and hydrocarbons in boiler tail flue duct.It was found that flue gas combustible content is about 0.1%~0.3%,the fly ash carbon content is 12.04%~44.66%,and the volatile content is 3.71%~13.20%;The collected fly ash was raised from ambient temperature to 1000℃ with a temperature rate of 10,20,30℃/min to analyze its combustion characteristics,and it was shown that ignition temperature and the heating rate of fly ash are positively correlated,and appropriately increase the heating rate,fly ash are less likely to fire;By analyzing mixing temperature flue gas after the high temperature flue gas counter the low,the lower limit concentration of fly ash explosion and the explosion limit oxygen concentration,it was found that the temperature of the SCR system could reach 364℃,and the fly ash concentration was less than 50 g/m^(3),which proves that mixing flue gas temperature can also make the SCR system work effectively,and the fly ash in the tail pipe is non-explosive during the process of the boiler start-up of the coal-fired power plant.