Design, Simulation And Experiment Investigation On A Multi-stage Self-preheating Burner

A set of multi-stage self-preheating burner and its experimental system which adapted tothe blast furnace gas was designed and developed for clean and efficient utilize of low heatingvalue(LHV)fuels according to technical advantages and realizing approaches of flamelesscombustion. Analyses including the air flow and pressure characteristics under cold state andcombustion and emission characteristics under hot state through Computational FluidDynamics (CFD) simulation and experimental research work.First of all, according to the summarized various new burning technologies and theirprinciples, a scheme of multi-stage self-preheating burner with some typical preheat chamberswere designed based on the gas backflow to preheat air and fuel. The specially designedexperimental system was confirmed after design, calculation and optimization, which mainlyincluded industrial boiler, blower, induced draft fan, cooling device, measuring device, dataacquisition and processing device, control and warning device. Then the experimental systemwas set up according to it.Secondly, the numerical simulations were down. Compared the theoretical basis andclassification of basic control equations, turbulent models, chemical composition transportand response simulation models, radiation models and NOxformation models and selected thesuitable ones for this research through the references and comparative method. The boundaryconditions, the choice of physical parameters, initialization, convergence criteria, theory andcalculation method of flue gas recirculation rate was described. And according to the differentcombustion chambers and preheat chambers, various physical model and suitable gridpartition method was built. After the respectively researches of flow, heat transfer andcombustion characteristics of combustion chambers and preheat chambers, obtained theoptimum ratio of combustion chamber's radius and length and compared the flue gasrecirculation rates, temperature fields, burn-out rates and NOxemissions when using differentpreheat chambers. The results verified the feasibility of realize flameless combustion of usingLHV fuels in this burner from numerical simulation.Finally, the experimental research works were down. In the cold state experiment,measured the speed and pressure distributions in the combustion chamber when using themulti-stage self-preheating burner and a traditional one, observe the backflow area andanalyses the flow and recirculation characteristics. In the hot state experiment, measured thetemperature field in the combustion chamber and obtained the combustion characteristics ofdifferent load&different excess air coefficient conditions when using different burners. Atlast, combined with the numerical simulation results, acquired the final conclusions through comprehensive contrast of combustion and pollutant emission characteristics that this designof burner and experimental system can realize flameless combustion when using blast furnacegas and meet the technical indicator which was high gasification efficiency, proved thefeasibility of research on the flameless combustion characteristics. The research accumulatedprecious experience for thorough and meticulous research in future.