关键词: 燃气分级燃烧器, 空气预热温度, 过剩空气系数, 氮氧化物

Abstract: By using CFD software Fluent，a numerical simulation was carried out to study the combustion behavior and NOx emission of a xylene tower in gas-oil burner. The problem of high NOx emission was analyzed and a novel low NOx staged-fuel burner structure was brought up. Based on the new burner structure，orthogonal simulations were conducted to study the influences of operating parameters (including air preheated temperature Tair, excess air factor α, and primary fuel gas mass ratio Rp) on the radiation surface heat flux （RSHF），radiation section outlet temperature （RSOT），flame height and volume fraction of NOx. Simulation results of the in-service burners showed good agreement with site running data，suggesting good prediction of the chosen models for the internal flow，radiation，combustion and NOx formation. Simulation results of the new burner showed that higher air preheated temperature could increase the radiative heat flux while also aggravating the NOx emission；excess air factor could enlarge the radiative heat flux and reduce NOx emission；varied primary fuel gas mass ratio made no obvious differences on both radiative heat flux and NOx emission. It was concluded that air preheated temperature of 220℃，excess air ratio of 1.05 and primary gas ratio of 0.24 were the optimal operating conditions，under which radiative heat flux was 37.45kW/m2 while NOx emission simulated to be 12.1μL/L.

Key words: staged-fuel burner, air preheated temperature, excess air factor, nitrogen oxide