Simulation And Optimization Of Combustion Performance In Inert Gas Generator

The inert gas generator is an important equipment that uses fuel to burn,generates inert flue gas with an oxygen content of less than 5%,and injects it into the cargo hold or enclosure containing dangerous goods to ensure the safety of the ship and offshore equipment.At present,there is little research on inert gas generators at home and abroad.This device is different from traditional oil-fired boilers.The main concern is the oxygen content of the flue gas and the economics of long-term operation.The numerical simulation method is used to study the internal combustion and flow of the inert gas generator combustion unit,which can provide guidance for the design,optimization and operation of the generator structure.In this paper,the 2500m~3/h direct-fired inert gas generator is taken as the research object.In the early stage,the test data of eight groups of different combustion loads were measured by bench test.The data analysis showed that the temperature in the furnace was increased with the increase of the combustion load.There is a small increase in the level.The Fluent software was used to simulate the cold and hot flow fields inside the furnace.The Realizable k-?model was used to simulate the turbulent flow.The discrete phase model was selected to simulate the fuel atomization process.The non-premixed combustion model was used to simulate the combustion.The radiation model simulates the heat transfer process.Under the rated working conditions,it is found that the turbulence intensity of the cold air increases greatly after passing through the air conditioner,and a recirculation zone is formed in the wall area of the front section of the furnace.Due to the influence of the vertical air intake structure,the air flows into the furnace and has a velocity moving in the positive direction of the Y-axis.Component.The hot flow field shows that the combustion speeds up the flow of the flue gas,and the flue gas flow rate at the exit of the furnace is six times that of the cold field.The temperature distribution in the first half of the furnace is uneven,and the combustion in the second half is gradually spread to the surrounding area.The combustion effect is good,and the average temperature at the exit position reaches 2000K.The oxygen concentration in the region with high temperature field in the furnace is low,the oxygen concentration at the outlet is evenly distributed and the oxygen content meets the emission requirements.Under the variable load simulation,when the excess air coefficient is 1.05 and 1.10,the simulated outlet smoke oxygen content is less than 5%,and the combustion effect in the furnace is better;when the excess air coefficient is greater than 1.15,the furnace hot temperature field The distribution is uneven,and the flue gas does not meet the requirements for injecting the cargo tank.As the combustion load increases,the temperature field of the furnace will move backwards,the temperature of each radial section will rise slightly,and the combustion will be sufficient under low load.The overload field will have a temperature field distribution that does not match the size of the furnace.It is not suitable for a long time.Operates under high load conditions.The simulation of the variable structure parameters shows that the flow field distribution of the coaxial intake air is more uniform than that of the vertical intake air,and solves the problem that the flow field concentrates on the upper wall surface of the furnace.The cold state velocity field of the curved blade inlet is more regular,and the recirculation zone is better distributed.The straight blade angle is 35°~37°,and when the number of blades is 12,the recirculation zone area is larger.The injection angle of the fuel is 60°or 80°,and when the initial diameter of the atomization is 50?m,the temperature field distribution of the furnace is better,and the oxygen content of the outlet flue gas is lower.