燃烧条件对准颗粒CO排放影响的数值模拟

NUMERICAL SIMULATION OF THE IMPACT OF PARTICULATE CO EMISSIONS UNDER COMBUSTION CONDITIONS

在烧结过程中料层不同位置温度、氧气浓度、空气流速等条件存在差异巨大,为探究烧结过程中燃烧条件对烧结准颗粒CO生成行为的影响,利用数值模拟的方法研究了不同准颗粒烧结过程。通过FLUENT软件,以多孔介质模型为基础,结合能量方程模型、组分输运方程模型、燃料燃烧以及污染物排放的反应动力学模型,以自定义功能(UDF)对各方程模型的源项进行定义与修正,建立了4种不同结构铁矿石烧结准颗粒,即S′型(裸露型)、S型(被覆型)、C型(外包型)和P型(球团型)的燃料燃烧过程模型,阐述了各种因素对烧结准颗粒中燃料燃烧行为及污染物排放特性的影响规律。模拟结果显示,准颗粒烧结过程CO排放规律随着燃烧条件的变化而发生改变,不同的反应条件对准颗粒内焦炭的燃烧速率有不同影响。当环境温度从1200 K升至1400 K时,准颗粒的CO排放总量下降了2%左右。较高的环境风速与氧气浓度都使准颗粒的CO排放浓度峰值增加,同时增加了焦炭的未完全燃烧程度。

In order to explore the influence of combustion conditions on the CO generation behavior of sintered quasi-particles in the sintering process,the sintering process of different quasi-particles was studied by numerical simulation.Through FLUENT software,based on the porous media model,combined with the energy equation model,component transport equation model,reaction kinetics model of fuel combustion and pollutant emission,the source terms of each range model were defined and modified by custom function(UDF),and four kinds of iron ore sintered quasi-particles with different structures were established,namely S'type(bare type),S type(covered type),The models of the fuel combustion process of type C(outsourcing type)and type P(pellet type)illustrate the influence of various factors on the fuel combustion behavior and pollutant emission characteristics in sintered quasi-particles.The simulation results show that the CO emission law changes with the change of combustion conditions in the quasi-particle sintering process,and different reaction conditions have different effects on the combustion rate of coke in the quasi-granular.When the ambient temperature rises from 1200 K to 1400 K,the total CO emissions of quasi-particles decrease by about 2%.The higher ambient wind speed and oxygen concentration both increased the peak CO emission concentration of quasi-particles,and the degree of incomplete combustion of coke increased.