Effect Of 90°bend On Flame Propagation For In-line Flame Arrester Pipeline

The combustible gas explosions occurred frequently in modern industry due to the rapid development of petrochemical and natural gas industries.The research on flame arrester has become an important subject in the fields of safe technology.Flame arrester is a kind of safety equipment which can prevent flammable gas and liquid vapors from spreading.The influence of pipeline structure on flame propagation in flame arrester is a hot and difficult topic in this field.This paper focuses on the experiments alongside with theory and numerical simulation on the explosion resistance processes in the 900 bend flame arresters pipeline.The main content and conclusions of this paper are as follows.(1)An experimental system of gas explosion and explosion resistance was set up in a 900 bend pipeline,which included high-precision gas mixing equipment,data acquisition device and sensor measurement system.The system designed was able to complete the test configuration of explosive mixture gas,explosion process pressure,flame speed and temperature testing work,the analysis of the data processing work.(2)Propane,ethylene,and hydrogen-air mixtures deflagration resistance processes in 900 bend flame arresters pipeline were investigated.The variation tendency of pressure time history indicate that,the pressure rises not obvious in the initial stage,and then the explosion pressure rises rapidly.In the 900 bend,explosion pressure peak value was higher,which appeared multiple-peak values and larger fluctuation due to pressure wave accumulated and steered.The quenching phenomenon occurred and the pressure gradually decreased when the flame contacted the arrester element.(3)A numerical model was set up to investigate ethylene-air premix deflagration flame propagation and quenching by crimped-ribbon flame arresters in 90° bend pipeline,the process of flame propagation and quenching was analyzed.Numerical results showed that the duration between flame front contacted 90° bend and propagated to the downstream straight pipe was short,and exhibited an increase time of approximately 4 millisecond.Flame front stayed in the surface of arrester element and did not pass through as it contacted the arrester element,which resulted in quenching.In the 90° bend,explosion pressure peak value was higher,which appeared multiple-peak values and larger fluctuation.The maximum overpressure along the outer surface initially increased and then decreased,eventually increased.Simulation result showed that front explosion pressure increased as initial pressure grew,and the two parameters presented a quadratic function relationship.And the initial pressure can also significantly increase the flame speed at the front of the arrester.The maximum explosion pressure and flame speed happened when the mixture was close to stoichiometric ratio.When the concentrations are 4%and 15%,no flame acceleration is observed during the process.