Engineering1012
Chemical
- Apr 18, 2016
- 29
New maintenance engineer here, working at a chemical plant.
Currently we have three vertical pumps for a sump in my unit. A primary always runs to maintain sump level at 40% and secondary pump kicks on when sump rises above 60%. The third is a backup. So the main issue is that the primary pump runs below or at minimum recommended flow(334 gpm) for 95% of the time, it isn't until we have rain or other dumps that allow the pumps to open up closer to their BEP (1300 gpm). All three pumps feed into one control valve.
Now there is a small 2" recirculation line that only provides about 120 gpm according to tests and actually dumps into the pumping chamber right at the suction of a pump which has its own air entrapment issues. With this poor design I am looking into sizing a new recirculation line to dump back in the settling chamber and then getting a Vfd for the primary (due to cost).
With the CV 100% open, the discharge pressure off the primary pump was 22psig. There is no other points to get a pressure reading downstream of the valve when it is loaded during normal ops.
My question is , what should my plan of attack be to size this line? Any advice or tips for a young engineer would be great. Thanks in advance!
Currently we have three vertical pumps for a sump in my unit. A primary always runs to maintain sump level at 40% and secondary pump kicks on when sump rises above 60%. The third is a backup. So the main issue is that the primary pump runs below or at minimum recommended flow(334 gpm) for 95% of the time, it isn't until we have rain or other dumps that allow the pumps to open up closer to their BEP (1300 gpm). All three pumps feed into one control valve.
Now there is a small 2" recirculation line that only provides about 120 gpm according to tests and actually dumps into the pumping chamber right at the suction of a pump which has its own air entrapment issues. With this poor design I am looking into sizing a new recirculation line to dump back in the settling chamber and then getting a Vfd for the primary (due to cost).
With the CV 100% open, the discharge pressure off the primary pump was 22psig. There is no other points to get a pressure reading downstream of the valve when it is loaded during normal ops.
My question is , what should my plan of attack be to size this line? Any advice or tips for a young engineer would be great. Thanks in advance!