采用选择性非催化还原脱硝技术的600 MW超超临界锅炉炉内过程的数值模拟

借助Fluent软件平台,对1台600 MW煤粉炉建立了数学模型,模拟了炉内流动、传热及燃烧过程.计算获得的炉膛出口平均烟温和烟气组分浓度与设计值符合良好,表明计算是合理的.采用三菱现代燃烧技术(MACT)燃烧技术和PM燃烧器使得NOx生成量较少,且一部分生成的NOx被还原,炉膛出口NOx浓度较低,为216 mg/kg,但可满足选择性非催化还原技术对初始NOx浓度的要求.根据选择性非催化还原反应的"温度窗"条件,适合进行选择性非催化还原脱硝反应的炉膛空间在标高为67m附近的区域,该区域内NOx总的分布规律是炉膛中心浓度低,壁面附近高,有利于采用还原剂从壁面喷射的方案.

Numerical Simulation of Furnace Process in a 600 MW Ultra Supercritical Boiler Utilizing Selective Noncatalytic Reduction Technology

Numerical simulation of flow,heat transfer,and combustion process in a 600 MW ultra supercritical pulverized coal boiler is performed using Computational Fluid Dynamics(CFD) code Fluent.The average temperature and concentration of gas composition at the furnace outlet are in a good consistent with the designed value,which indicates that mathematical models and calculation method are valid.NO formation is low because of Mitsubishi Advanced combustion technology and PM burner, and partial of NO produced is deoxidizated.NO emission at furnace outlet is 216mg/kg,which meets the initial NO concentration requirement of Selective Noncatalytic Reduction Technology(SNCR) process.According to the "temperature window" requirement of SNCR process,the proper region for SNCR process is around 67 meters high horizontal cross section in the furnace.The NO concentration in the region decreases gradually from near the water wall to the center of the furnace,which is benefit for injecting reducing agent from water wall.Unburned CO is very little and exists only in limited zones near the two lateral water walls,which has small influence on NO removal.According to temperature profile and gas species as well as the arrangement of superheaters,an approach for injecting the reducing agent of SNCR process is suggested.