TPP unit was in shutdown for 2 months and when started the casing expansion value is coming 15 mm which was 6-7 mm before shutdown. though turbine tripping from casing expansion is not there, want to ask if increase in value is a matter of concern.

 

Did someone "calibrate" or make any changes to the calibration or configuration or set-up of the expansion probe/sensor?

 

It is stabilized at nominal temperature and nominal load, or it is still in warm up period??

 

> Did someone "calibrate" or make any changes to the calibration or configuration or set-up of the expansion probe/sensor? <

Nobody has made any changes or disturbed the calibration

 

> It is stabilized at nominal temperature and nominal load, or it is still in warm up period?? <

the reading is stabilised at 14mm and the TPP is in running condition. The reading was 7mm before shutdown.

 

GAJENDRA... is the current displacement (14mm) exactly twice the original displacement (7mm)?

If so, how do the thrust-bearing temperatures compare?

Regards, Phil Corso

 

Do you have relative expansions measurement? If so, and if the casing is really displaced 7 mm more than normal, you should be able to see the same change in relative expansion. Relative expansion is your critical parameter more than casing expansion. Other points to check: are you operating at the same steam conditions? What about pedestal nuts. are they "free"? Or better: were they free before? How far are you from this 14mm to the alarm point?