烟气再循环率对水泥回转窑加热过程的影响  

Effect of flue gas recirculation rate on heating process of cement rotary kiln

作　　者：张蕊 于庆波 娄一荻 Rui ZHANG;Qingbo YU;Yidi LOU(School of Metallurgy,Northeastern University,Shenyang,Liaoning 110819,China)

机构地区：[1]东北大学冶金学院,辽宁沈阳110819

出　　处：《过程工程学报》2024年第9期1027-1035,共9页The Chinese Journal of Process Engineering

基　　金：国家重点研发计划项目(编号:2017YFB0603603);辽宁省“兴辽英才计划”项目(编号:XLYC1802002)。

摘　　要：为降低水泥回转窑加热过程中CO_(2)和NO_(x)的排放,引入一种清洁燃烧技术:烟气再循环技术。针对某2500 t/d水泥回转窑建立物理和数学模型,利用CFD软件对窑内加热过程进行数值模拟,考察了常规空气燃烧和烟气再循环燃烧两种燃烧方式对窑内温度场、流场、浓度场、NO_(x)排放量及生料分解率的影响。结果表明,烟气再循环技术可降低窑内最高温度,最高降幅达13.6%。随着烟气再循环率增加,窑内高温区面积逐渐减小,但平均温度几乎不变,说明此技术在减少局部高温区的同时,仍能使窑内平均温度满足水泥生产的温度要求。烟气出口的CO_(2)浓度提高了45.4%,烟气出口的NO_(x)浓度由235.7 mg/m^(3)降至39.4 mg/m^(3),NO_(x)排放量减少了83.3%,说明该技术既有利于CO_(2)的捕集利用,又能有效降低水泥行业NO_(x)的排放。生料分解率虽降低了8%,但仍保持在90%以上,能满足水泥生产的产量要求。In order to reduce the emission of CO_(2) and NO_(x) during the heating process of cement rotary kiln,flue gas recirculation technology was introduced as a clean combustion technology.A physical and mathematical model of a 2500 t/d cement rotary kiln was established,and the numerical simulation of heating process in the rotary kiln by using CFD software.The effects of conventional air combustion and flue gas recirculation combustion on the temperature field,flow field,concentration field,NO_(x) emission and raw meal decomposition rate in the kiln were compared and analyzed.The results showed that the flue gas recirculation technology can reduce the maximum temperature in the kiln,and the maximum reduction was 13.6%.With the increase of flue gas recirculation rate,the area of the high temperature zone in the kiln gradually decreased,but the average temperature was almost unchanged,which indicated that the flue gas recirculation technology can still make the average temperature in the kiln met the temperature requirements of cement production while reducing the local high temperature area.The CO_(2) concentration at the flue gas outlet increased by 45.4%,which was conducive to the capture and utilization of CO_(2).The NO_(x) concentration at the flue gas outlet decreased from 235.7 mg/m^(3) to 39.4 mg/m^(3),and the NO_(x) emission decreased by 83.3%,indicating that this technology was not only conducive to the capture and utilization of CO_(2),but also can effectively reduce the NO_(x) emission in the cement industry.Although the decomposition rate of raw meal reduced by 8%,but remained above 90%,which still met the output requirements of cement production.

关 键 词：水泥回转窑 烟气再循环技术 烟气再循环率 加热过程 数值模拟 

分 类 号：TQ172.622[化学工程—水泥工业]