Interlock issues in hydrogenation units
Thread Content
Hello, everyone in the marine community. I would like to ask you a question regarding the interlocks of hydrogenation units. Why, after the emergency pressure relief valve of a hydrogenation unit opens, is it usual to shut down the high-pressure feed pump and cut off the fuel gas to the heater? So why shut down the high-pressure feed pump?
After the emergency pressure relief valve opens, during the time it takes for the valve to return to its closed position: 1. If the high-pressure feed pump is not stopped, the system will continue to feed material, which will then be discharged into the exhaust system through the emergency pressure relief valve, resulting in waste of material. 2. If the fuel gas to the heating furnace is not cut off and the high-pressure feed pump continues to operate, it will increase the time required for the emergency pressure relief valve to return to its closed position (it is also possible that even with the valve fully open, the system pressure cannot be reduced to the level at which the valve closes). This could lead to: (1) the pressure not being able to dissipate and instead continuing to rise (this is related to the nominal diameter of the pressure relief piping), resulting in equipment explosion ； (2) The pressure energy is released, but over a long period of time, resulting in significant waste of material.