An attempt was made to extend mild combustion to forward flow furnace, such as the refinery and petrochemical tube furnace. Three dimensional numerical simulation was carried out to study the performance of this furna...An attempt was made to extend mild combustion to forward flow furnace, such as the refinery and petrochemical tube furnace. Three dimensional numerical simulation was carried out to study the performance of this furnace. The Eddy Dissipation Concept(EDC) model coupled with the reaction mechanism DRM-19 was used. The prediction showed a good agreement with the measurement. The effect of air nozzle circle(D), air nozzle diameter(d), air nozzle number(N), and air preheating temperature(Tair) on the flow, temperature and species fields, and the CO and NO emissions was investigated. The results indicate that there are four zones in the furnace, viz.: a central jet zone, an ignition zone, a combustion reaction zone, and a flue gas zone, according to the distribution profiles of H_2 CO and OH. The central jet entrains more flue gas in the furnace upstream with an increasing D while the effect of D is negligible in the downstream. The air jet momentum increases with a decreasing d or an increasing Tair, and entrains more flue gas. The effect of N is mainly identified near the burner exit. More heat is absorbed in the radiant section and less heat is discharged to the atmosphere with a decreasing d and an increasing N as evidenced by the flue gas temperature. The CO and NO emissions are less than 50 μL/L and 10 μL/L, respectively, in most of conditions.展开更多
This paper presents the experimental and numerical results for a two stagecombustor capable of achieving flameless combustion with liquid fuels for different thermalheat inputs of 20,30,40 and 60 kW and heat release d...This paper presents the experimental and numerical results for a two stagecombustor capable of achieving flameless combustion with liquid fuels for different thermalheat inputs of 20,30,40 and 60 kW and heat release density of 5-15 MW/m^(3).Combustioncharacteristics and pollutant emissions are studied for three different fuels,kerosene,diesel andgasoline.The influence of droplet diameter on pollutant emissions at all conditions is studied.The fuel and oxidizer are supplied at ambient conditions.The concept of high swirl flows hasbeen adopted to achieve high intemal recirculation rates,residence time and increased dilutionof the fresh reactants in the primary combustion zone,resulting in flameless combustion mode.Air is injected through four tangential injection ports located near the bottom of the combustorand liquid fuel is injected through a centrally mounted pressure swirl injector.Computationalanalysis of the flow features shows that decrease in the exit port diameter of the primarychamber increases the recirculation rate of combustion products and helps in achieving theflameless combustion mode.Based on preliminary computational studies,a 30 mm primarychamber exit pont diameter is chosen for experimental studies.Detailed experimentalinvestigations show that flameless combustion mode was achieved with evenly distributedcombustion reaction zone and unifom temperature distribution in the combustor.Pollutant emissions of CO, NO_(x),C_(x)H_(y) are measured and compared for all operating conditions ofdifferent fuels and different thermal inputs. The acoustic emission levels are reduced by6-8 dB as combustion mode shifts from conventional mode to flameless combustion mode.展开更多
基金supported by the technology development fund of China Petroleum & Chemical Corporation (Sinopec 312016 and 314054)
文摘An attempt was made to extend mild combustion to forward flow furnace, such as the refinery and petrochemical tube furnace. Three dimensional numerical simulation was carried out to study the performance of this furnace. The Eddy Dissipation Concept(EDC) model coupled with the reaction mechanism DRM-19 was used. The prediction showed a good agreement with the measurement. The effect of air nozzle circle(D), air nozzle diameter(d), air nozzle number(N), and air preheating temperature(Tair) on the flow, temperature and species fields, and the CO and NO emissions was investigated. The results indicate that there are four zones in the furnace, viz.: a central jet zone, an ignition zone, a combustion reaction zone, and a flue gas zone, according to the distribution profiles of H_2 CO and OH. The central jet entrains more flue gas in the furnace upstream with an increasing D while the effect of D is negligible in the downstream. The air jet momentum increases with a decreasing d or an increasing Tair, and entrains more flue gas. The effect of N is mainly identified near the burner exit. More heat is absorbed in the radiant section and less heat is discharged to the atmosphere with a decreasing d and an increasing N as evidenced by the flue gas temperature. The CO and NO emissions are less than 50 μL/L and 10 μL/L, respectively, in most of conditions.
文摘This paper presents the experimental and numerical results for a two stagecombustor capable of achieving flameless combustion with liquid fuels for different thermalheat inputs of 20,30,40 and 60 kW and heat release density of 5-15 MW/m^(3).Combustioncharacteristics and pollutant emissions are studied for three different fuels,kerosene,diesel andgasoline.The influence of droplet diameter on pollutant emissions at all conditions is studied.The fuel and oxidizer are supplied at ambient conditions.The concept of high swirl flows hasbeen adopted to achieve high intemal recirculation rates,residence time and increased dilutionof the fresh reactants in the primary combustion zone,resulting in flameless combustion mode.Air is injected through four tangential injection ports located near the bottom of the combustorand liquid fuel is injected through a centrally mounted pressure swirl injector.Computationalanalysis of the flow features shows that decrease in the exit port diameter of the primarychamber increases the recirculation rate of combustion products and helps in achieving theflameless combustion mode.Based on preliminary computational studies,a 30 mm primarychamber exit pont diameter is chosen for experimental studies.Detailed experimentalinvestigations show that flameless combustion mode was achieved with evenly distributedcombustion reaction zone and unifom temperature distribution in the combustor.Pollutant emissions of CO, NO_(x),C_(x)H_(y) are measured and compared for all operating conditions ofdifferent fuels and different thermal inputs. The acoustic emission levels are reduced by6-8 dB as combustion mode shifts from conventional mode to flameless combustion mode.
