尿素合成塔爆炸事故机理的研究

尿素合成塔工艺条件复杂,体积庞大,内部物料状态复杂,需要在高温、高压下操作,国内外曾发生过几起著名的尿素合成塔爆炸事故,事故后果非常严重。工艺条件的复杂性加大了事故分析的难度,目前对事故原因众说纷纭。利用数值模拟软件,对尿素合成塔爆炸过程进行研究,对爆炸机理进行分析,对事故发生的原因进行探讨,为预防同类事故提供一定的依据。分析了顶部气相空间爆炸性混合体系的形成和爆炸过程,结合数值模拟得出关键点的压力变化和气相冲击波最终的压力,依据能量守恒推导出液相中冲击波的压力。利用数值模拟得出冲击波在液相中的传播速度和叠加的情况,综合反射、直接透射两部分冲击波进入液相的时间差,找到位于筒体底部的叠加点,冲击波在该处叠加造成筒体破裂,过热液体瞬间气化喷出,引发破坏更大的二次蒸汽大爆炸。

The research of urea reactor explosion mechanism

Urea reactor is operated at high temperature and high pressure.Several destructive explosions happened in and abroad.However,the complexity of process conditions increases the difficulty in the accident investigation.There is no agreement on the cause of the explosion.In the present paper,we simulated the explosion process by using the software FLUENT.The mechanism of explosion and the cause of the accident are analyzed,which provides some references to prevent similar accidents.Explosive mixture system of the top gas space and explosion process is analyzed.Combined with numerical simulation,the pressure change at key point and eventual pressure of gas phase shockwave were obtained,The liquid pressure wave was deduced according to energy conservation.The shock wave propagation velocity and superposition in the liquid ammonia were obtained by numerical simulation.Combined with the time difference of reflection,direct transmission liquid shock waves,the superimposition spot located at the bottom of cylindrical shell was found,which results in the tube body to destroy and overheating fluid ejected,even secondary explosion which is more intensive and destructive.