Topic: After the small pump is operating normally, is the minimum return line closed?
Thread Content
Our factory’s small pumps basically do not shut off the minimum return line after starting up; this not only increases the load on the pumps but also results in an inability to transport as much fluid under certain conditions! Everyone, please share whether you need to turn off the minimum return line after the small pump in your system starts operating
In the methanol washing units I’ve seen, all of the minimum reflux lines for the operating pumps are kept open; I think they can be turned off when the system is operating stably, and reopened when there are fluctuations and instability
All the minimum return lines should be open
The minimum return line is fully open when the pump starts; there is no need to keep it open during normal operation! Ours are all closed!
Reply to 4# 654262293: The minimum return line should be fully open when the pump starts; there is no need to keep it open during normal operation! Is it enough to close the manual valve during normal operation?
You are referring to the automatic circulation valve of the low-temperature methanol washing process; there is no need to close the manual valve in front of it!
The return line is only used when starting the pump; once it is operating normally, we turn it off
Turning it on or off is related to the degree of automation in control. Some units have a high degree of automation; the minimum reflux switch or digital switches are adjusted according to changes in load, which ensures the proper operation of the system and facilitates long-term operation of the pump. Some units have a low level of automation; the minimum reflux function generally only operates when the pump is started, and it is rarely used or not used at all during normal operation.
As long as the minimum return valve is selected properly, there will be no flow in the minimum return line during normal operation, and it should remain open.
I won’t open the return valve of small pumps; as for who should do it, I certainly don’t recommend it； But the return flow of the large pump must be turned on.