Corrosion in Propane Deasphalting Unit in a Lube Producing Refinery: A Case Study

摘要

Propane deasphalting is a process of recovery of hydrocarbon distillates from vacuum residue by extracting with liquid propane. A plated tower is used to carry out extraction where extract containing the deasphalted oil and raffinate containing the asphalt are separated. Extract and raffinates are then subject to propane recovery sections wherefrom propane is recovered and reused in extraction. Complete recovery of propane from deasphalted oil is carried out by flashing alone, but recovery from asphalt requires heating in a furnace followed by flashing. Severe corrosion has been observed in the propane condensers, coolers, and the overhead lines of the flashers and stripper columns. Studies have indicated that cracking of asphalt at the prevailing operating temperature and pressure, generating hydrogen sulfide, was the sole reason for corrosion. The problem has been minimized by adjusting the temperature and pressure without affecting the propane recovery efficiency.