Emergency shut-off valve at the outlet of the feed pump for diesel hydrogenation
Thread Content
In a diesel hydrogenation unit, according to the documentation, the emergency shut-off valve at the pump outlet is closed when any of the following conditions occur: specifically, when the pump outlet flow rate is low low – based on a two-out-of-three criterion (less than 40 t/h). Why must the pump outlet shut-off valve be closed urgently when the flow rate is very low? What reasons or conditions are taken into account for this? Those who know, please share. Thanks
During normal operation, when the flow rate drops below a certain level, the system assumes that there is a fault with the hydrogen feed pump and shuts it down. This is done to prevent high-pressure material behind the pump from flowing back into the crude oil buffer tank after the pump stops, thereby avoiding risks such as explosions. Therefore, it must be cut off urgently
In the face of similar problems, it is best to start with a flowchart (process flow diagram) to understand the principle behind the process, which can help resolve many doubts. For reference.
An additional aspect at the first floor is that, once the pump outlet is shut off, the safety valve at the pump inlet will open and allow oil to flow into the crude oil tank.
I recall an accident: an old set of equipment lacked an emergency shut-off valve at the outlet. After the feed pump stopped operating, the check valve at the outlet failed, causing system pressure to flow back from the hydrogen mixing point to the pump inlet and further to the raw material buffer tank. Since the safety valve of the buffer tank was not in use, the buffer tank, designed to withstand a pressure of 0.4 MPa, was ruptured by the system pressure of 10 MPa, resulting in casualties.
It is possible to learn again about the 2018 Jiujiang Petrochemical diesel hydrogenation accident