Failure analysis of the blackwater regulating valve in the coal chemical industry

•Failure is caused by a combined effect of cavitation erosion and particle erosion.•High-speed flow is the main factor leading to the damage of the valve spool.•More severe damage is on the waist rather than the head of the valve spool.•WC particles are pulled out after the Co phase is preferred erosion and corrosion.•Numerical results are in good agreement with actual failure morphology. Valves’ failure is common in the coal industry due to their severe working conditions, like high-velocity erosion, cavitation erosion, and so on. The damage morphologies of the blackwater regulating valve (BRV) in coal chemical equipment were investigated by stereo microscopy, metallographic microscopy, and scanning electron microscopy (SEM). Failure causes of the valve were analyzed from the material structure, hole defects, composition, hardness of the material, corrosive media, and computational fluid dynamics (CFD). The results showed the damage on the valve spool and seat was attributed to the combined effect of slurry erosion, cavitation erosion, and corrosion. The soft cobalt phase was preferentially removed followed by the pulling-off of WC particles, which is the failure mechanism of BRV.