After major repair in 2001

the low-pressure differential expansion of unit no.1 in Lianzhou Power Plant has awfully changed

Through analysis of the operating conditions

it has been discovered that the comparetively obvious relation is existing between the variation of low-pressure differential expansion(LPDE)and the load

the vacuum in condenser

and the gland seal pressure.The LPDE increases along with the increase of vacuum in conderser

and decreases with the reduce of vacuum in condenser;the LPDE decreases along with the increase of load

and increases with the reduce of load.Through inspection of the differential expansion measuring circuit and inspection in major repair

it has been discovered that the centre-line surface of low-pressure cylingder near the gland seal being damaged by steam blowing.It is believed from analysis that the cause leading to abnormal differential expansion in normal operation of unit no.1 is the steam leakage from the centre-line surface of low-pressure cylinder near the gland seal into final stage of the low-pressure rotor.For this

corresponding solving measures have been taken

making the differential expansion achieving the normal value.