Mitigating probability of fire in a high pressure oxygen system by appropriate design of divergent pipe leading to particle filter.

Oxygen gas at 99.6% purity is used in steel melting shop of steel plants at a pressure of 40 bara, which is reduced to 20 bara in a pressure reducing station (PRS). Incidents of fire occur with high purity and high pressure oxygen which can be mitigated improving system configurations, control of operating parameters and system practices. An incident of fire in a PRS in an Indian steel plant is analysed to suggest such improvement. The first visible source of fire at the upstream end of a diffuser pipeline leads to the hypothesis of accumulation of solid particles at that location. Computational Fluid Dynamic (CFD) analysis with calculations of static
charge generated on the particles shows that probability of particle accumulation increases with the increase of angle of divergence of the diffuser connecting the filter. Total divergence angle of diffuser should not exceed 14o to mitigate at least one of many possible causes of oxygen fire.