How to relieve pressure in the hydrogenation feed pump of a hydrogenation unit

I’m not entirely clear about your manufacturing processes and the design of the relevant pipelines: we once had a BD delivery pipeline, where the temperature was around 10 degrees under normal conditions； If, after the transfer through some pipelines is completed and the valves are closed, a liquid seal is formed, the pressure in the pipelines can rise sharply as the temperature increases, which may lead to the rupture of the explosion-proof membranes in those pipelines and the activation of safety valves. Therefore, in the design, we ensure that when the valves are in the closed position, there remains an opening of about 10% in practice ； However, there was a pipeline for which valve control was not taken into account initially; we eventually carried out modifications by adding pressure monitoring so that the valve would open when the pressure reached a certain level ； Due to the high pressure you mentioned ； There may be two reasons: pressure increase due to the liquid seal ； Another issue is that the pressure is so high when the vehicle is parked ； (It is estimated that the first possibility is more likely.) If only pressure relief is taken into account ； Consider 1. Venting to the flare pipeline ； 2. Could it be considered to add a small bypass line between the pump’s outlet and inlet valves? This bypass line could be activated during shutdown to release the outlet pressure into the material storage tank ； 3. The outlet valve closes a little later when parking ； Allow some of the liquid in the pipeline to flow into the system, creating a certain amount of space in the pump outlet pipeline; in this way, even if the pressure rises, it will only be slightly higher than the saturated vapor pressure of H2 at that temperature ；

I’m not entirely clear about your manufacturing processes and the design of the relevant pipelines: we once had a BD delivery pipeline, where the temperature was around 10 degrees under normal conditions； If, after the transfer through some pipelines is completed and the valves are closed, a liquid seal is formed, the pressure in the pipelines can rise sharply as the temperature increases, which may lead to the rupture of the explosion-proof membranes in those pipelines and the activation of safety valves. Therefore, in the design, we ensure that when the valves are in the closed position, there remains an opening of about 10% in practice ； However, there was a pipeline for which valve control was not taken into account initially; we eventually carried out modifications by adding pressure monitoring so that the valve would open when the pressure reached a certain level ； Due to the high pressure you mentioned ； There may be two reasons: pressure increase due to the liquid seal ； Another issue is that the pressure is so high when the vehicle is parked ； (It is estimated that the first possibility is more likely.) If only pressure relief is taken into account ； Consider 1. Venting to the flare pipeline ； 2. Could it be considered to add a small bypass line between the pump’s outlet and inlet valves? This bypass line could be activated during shutdown to release the outlet pressure into the material storage tank ； 3. The outlet valve closes a little later when parking ； Allow some of the liquid in the pipeline to flow into the system, creating a certain amount of space in the pump outlet pipeline; in this way, even if the pressure rises, it will only be slightly higher than the saturated vapor pressure of H2 at that temperature ；

For the high-pressure feed pump in the hydrogenation unit, both pressurization and depressurization are achieved through the return line to the tank; isn’t there a return line at the outlet of your high-pressure feed pump? It’s just a pipeline that returns directly to the hydrogen feed buffer tank!

The design pressure of the pump body for high-pressure pumps is very high, allowing it to withstand the maximum allowable operating pressure; however, mechanical seals can only handle a pressure difference of up to 4 MPa. Therefore, high-pressure pumps have a minimum flow line to prevent excessive pump vibration and to relieve pressure as well. For hazardous media, safety valves are sometimes installed after the inlet valve, primarily to protect the mechanical seal.