We are studying to depressurize the DCU gas recovery area like that has in the Diesel Hydrotreater by a button in the DCS in case of emergency. We are thinking to depressurize by 10-15 min all the gas recovery area. My question. Any other DCU has this kind of system ? We are concerned about some damage inside the equipment’s because the rapid depressurize. We had a accident in the gas recovery area of a FCCU and we are concerned because both gas recovery area are similar.
It is not common to have a depressurization system on the Coker gas plant. For systems that are in refineries that are close to residential communities, the possibility of a high-pressure leak with high concentrations of H2S could result in a toxic vapor cloud exposing off-site personnel to H2S at high concentrations. In a case such as this, it might be necessary to install a rapid depressurization system. Decreasing the pressure to ambient within 15 minutes would be a reasonable design parameter. The trays in the towers would have to be checked to make sure the depressurization rate did not exceed the maximum uplift the trays can withstand. The normal tray design as an uplift resistance of roughly 0.5 to 0.7 psi. Standard trays can be designed to provide an uplift resistance of 1 psi. These are somewhat dependent on the tower diameter. I think all the other internals in the gas plant should be able to withstand the rapid reduction in pressure without incident.