蓄热式加热炉烟气吹扫系统设计应用

Design and application of regenerative heating furnace flue gas purge system

蓄热式加热炉作为冶金行业重要设备,主要用于钢坯加热,以高、转炉煤气等为燃料,采用周期换向燃烧方式,在换向时烧嘴会向大气中排放煤气,换向动作导致的煤气放散率高达3%~7%,造成资源浪费和环境污染。为了节约资源,减小污染,解决蓄热式加热炉在燃烧换向时造成的煤气放散问题,最直接的回收利用途径是将公共管道内的残留煤气吹扫至炉膛进行燃烧。现对某钢厂一座160 t/h蓄热式加热炉进行改造,在现有操作平台上加装烟气吹扫系统,烟气吹扫系统是从煤气烟气管道上引出一路用来吹扫管道,通过引风机将煤气烟气加压作为吹扫气源,将吹扫管道与煤气换向阀底部相接,通过调节原有煤气换向程序,配合响应快速的控制阀门进行吹扫过程的启停。吹扫时,管道内提前加压后的烟气喷出,迅速将公共管道内残留的煤气吹至炉膛内进行燃烧,以此达到放散煤气减排的效果。最后进行了工程实践,对比了改造前后系统炉温、炉压、CO减排效果以及经济性。已改造的加热炉,单次吹扫体积为37.05 Nm 3,按照加热炉单次换向周期60 s,加热炉年工作时间按330 d计算,年吹扫体积为1760.62万Nm 3,吹扫效率按照90%计,则年煤气排放量为1584.56万Nm 3,对应厂用煤气价格为0.13元/Nm 3,一年可节约成本206万元。蓄热式加热炉反吹系统可实现CO减排率高达90%以上。

As an important equipment in the metallurgical industry,the regenerative heating furnace is mainly used for billet heating.Using the high gas and converter gas as fuel and adopting the periodic reversal combustion method,the burner emits off-gas into the atmosphere during the reversal combustion process.The gas emission rate caused by the reversing action reaches to 3%-7%,causing waste of resources and environmental pollution.In order to save resources,reduce pollution,and solve the problem of gas emission caused by regenerative heating furnaces during combustion reversal,the most direct way of recycling is to sweep the residual gas in public pipes into the furnace for combustion.Now,the 160 t/h regenerative reheating furnace of a steel plant is being modified,and a flue gas purge system is installed on the existing operating platform.The flue gas purge system is to lead all the way from the gas flue gas pipeline for purging.The gas flue gas as the purge gas source is pressurized by the induced draft fan,and the purge pipe is connected with the bottom of the gas reversing valve.By adjusting the original gas reversing program and cooperating with the fast response control valve,the start and stop of the scanning process is carried out.During the purge,the flue gas pressurized in advance in the pipeline is ejected,and the residual gas in the public pipeline is quickly blown into the furnace for combustion,so as to achieve the effect of gas emission reduction.At last,the engineering practice was carried out,and the system furnace temperature,furnace pressure,CO emission reduction effect and economy before and after the transformation were compared.For the renovated heating furnace,a single purge volume is 37.05 Nm 3.According to the single reversal cycle of the heating furnace for 60 s,the annual working time of the heating furnace is calculated based on 330 days and the annual purging volume is 17.6062 million Nm 3.If the purging efficiency is calculated as 90%,the annual gas emission is 15.8546 million Nm 3,and the corresponding factory gas price is 0.13 yuan/Nm 3,which can save 2.06 million yuan a year.With the application of the regenerative heating furnace backflushing system,the CO emission reduction rate is as high as 90%.