Vacuum Stand Test

[Wazza1717]

Hi All

I'm troubleshooting poor vacuums on a surface condenser. Typical steam flow-rate is 80 t/h. Has anyone had any experience in a vacuum stand test, whereby you isolate the ejectors from the process and monitor how quickly you lose vacuum. We lost 10 kPa in 6 minutes. I'm trying to determine if from experience this is an unreasonable amount which points to an air-leak?

Also, we isolated the ejectors from the process and ran the motive steam only. We pulled a vacuum of 36 kPa absolute at suction of first stage. We've ruled out strainer blockages, steam quality problems, intercondeser blockages/fouling etc. some wear is visible on the nozzles - has anyone had experience with replacing worn nozzles and seeing improved performance?

Thanks
W

 

[sshep]

Wazza,
10 kPa seems like alot and does point to an air leak (or non-condensibles in the steam).

80ton/hr is flow that we would expect to a steam turbine, not to vacuum jets, so a picture would help understand your test. "First stage" indicates multiple stages of after jets.

If 34kPa was your limit, what pressure do you get when the jets are running? What was the expected best surface condenser pressure based on your CW temperature?

This is just my opinion and others may see it different: Replacing slightly worn nozzles are not going to help you. If you measure the flow of your motive steam and it is at design for the nozzle, then slight wear is not a problem, but if it is above design then you should replace.

best wishes,
sshep