Regarding the difference between valve-opening start-up and automatic start-up, as well as the exhaust issue for pumps that start automatically
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Hello everyone. Those who are familiar with on-site petrochemical operations would like to confirm whether valve opening for startup and automatic startup refer to the same concept, or whether automatic startup is just one type of valve opening for startup. Starting with the valve open means that the outlet valve of the standby pump is in an open position; when switching pumps, it can be opened manually on the control panel, without the need to open the outlet valve in advance. Auto-starting refers to the automatic activation of the standby pump when a cascade occurs, provided that the standby pump is already in a state where its valve is open and it can start operating. If the above understanding is correct, are all pumps that start by opening a valve equipped with auto-start functionality? Another issue relates to vertical cartridge pumps; pumps used for transporting hydrocarbons at low temperatures often require exhaust ventilation from both the pump body and the sealing chamber. The exhaust pipeline of the pump body leads directly to the suction tank, which is no problem. However, the exhaust valve of the sealing chamber should be in the open position (for exhaust) before the pump is started, and it needs to be closed before starting the pump. If this pump is set to start automatically, it becomes impossible to predict and carry out exhaust operations in advance when the pump is shut down via interlock. How is this handled in actual field situations?
First, the function of the check valve before the pump outlet valve must be taken into consideration； II. For standby pumps that need to be set up automatically, the function of the check valve installed in front of the pump also needs to be taken into consideration. Furthermore, to prevent leakage from the check valve behind the pump, it is necessary to consider installing a gauge line that runs from the pump manifold back to the valve in front of the pump, in order to maintain pressure and replenish fluid, thereby ensuring that no gas enters the pump.