LNG Turbo expander Jammed

[MIANCH]

Hi All,
we are commissioning a LNG Turbo Expander and facing a big problem that is Expander jammed,here is the sequence of event,
During commissioning our seal gas pressure went hi upto three barg and normal range was one barg while lube oil pump was running normal.
Turbo rotated about upto 300 rpm. And later on we tried to start but Turbo Expander not spined at all.
We opened the Trubo and Recompressor suction and discharge spools to check it but unfortunately found that Turbo is jammed.
Hence any one have experience like this please share.
10815L

 

[MortenA]

What exactly is jammed? I know of an application where the shaft was "cut" by electrostatic charges (due to a high methanol content in gas). This was solved with a new shaft and magnetic oil in the bearings. This is only 2. hand info so i really cant give you more info.

Bets regards, Morten

 

[MIANCH]

Hi Morten,
on inspection we found that speed probe obstructed the turbo shaft,is this possible that 62 barg gas can't rotate it and very small probe stopped turbo.
Before startup every probe was checked by auto control engineer and he reported gap volts are ok and in limit.
10815l

 

[MikeHalloran]

It's entirely credible that a small probe could jam the turbo. The flowing gas can't really develop a lot of torque, and the power input is not great until the RPM goes up, a lot, from 300 rpm.



Mike Halloran
Pembroke Pines, FL, USA