Air ejector troubleshooting

[Jordan-111]

We are experiencing "sudden loss of vacuum" or "pressure spike" on our air ejector system (2-3 times a day). The vacuum unit is a two-stage ejector with a direct contact inter-condenser. The unit is fairly new.
Design data: Operational data (when broken sonic wave): When running good:
1st stage suction: 1.3 inHgA 1.95inHgA
No 1st stage design discharge pressure 11 inHgA 9.8inHgA
2nd stage suction: 6.7 inHgA 7.88 inHgA 5.9inHgA
2nd stage discharge: 29.9 inHgA Constant backpressure(discharge to atmosphere) Constant backpressure
Cooling water flow: 80 USGPM 80 USGPM 80 USGPM
Inlet temperature: 67F 62 F 61F
Outlet temperature: 98F 94.5F 93.8F
Motive steam temperature: 500F 450F 450F
Motive steam pressure: 165PSIG 166PSIG 166 PSIG

We tried shutoff pressure test 3 times, they all generated different 1st stage suction pressure. (it could be that our instrument is broken)
I think the 2nd stage was broken due to excessive non-condensable loading, either from cooling water or there might be a leak somewhere in the system that causes the 2nd stage break operation.
Thanks in advance for the responses.
Regards.

 

[pierreick]

Hi,
Seems OK! You may want to test them before reassembly.
Pierre

 

[Jordan-111]

Hi Pierre,
We bought a new spray nozzle and we will install the new one.
Do you see any issue with the tailpipe arrangement from the inter-condenser?
Jordan

 

[pierreick]

Hi,
Nope, what is the purpose for this valve? You may accumulate dirt.The line should be obstacle free.
Pierre

 

[Jordan-111]

Hi Pierre,

The valve is always open. When it closes, it is mainly for back filling the ejector system to check for leaks.

Jordan

 

[pierreick]

Hi,
To comfort you with piping and inter condenser consider this paper from Graham.
Flanges are often a source of leaks. The best way is to eliminate them when possible. Use scotch tape to perform leak tests. I'm not convinced with the manual valve, even open could be a source of accumulation of dirt.

Pierre

 

[Jordan-111]

Hi Pierre,

We are just trying to start up from shutdown this morning and unfortunately, the ejector broke performance.
We ran a deadheaded test on the ejector:
1st suction: 0.93 inHgA. 1st stage discharge: 6.5 inHgA.
2nd suction: 3.61 inHgA and 2nd discharge to atmosphere: 0.46 inHg.

Do you see anything wrong with these sets of values? I think the 2nd suction and 1st discharge are too high even including the impact of gas in the cooling water.
We did a leak test on the ejector prior to startup, and there is nothing leaking on the ejector system.

Jordan

 

[pierreick]

Hi,
Sorry I cannot support more.
How is the situation today, several days after restart?
Pierre