Precautions in unit start-up

1.7.1 Pay attention to the operating condition of all automatic governing devices, change into manual governing control if any fault or poor governing, and contact the thermodynamic personnel to treat.

1.7.2 Pay attention to listening if the unit sound is normal.

1.7.3 Pay attention to checking if water level of condenser, deaerator and HP&LP heater are within normal range.

1.7.4 In load up, monitor if the generator air temperature is normal and adjust the rotor water inlet pressure to normal in time.

1.7.5 As vibration over critical speed exceeds 0.254mm, but protection refuses to operation, trip to shut down the turbine manually, put continuous turning into operation, measure shaft deflection, find out cause and remove fault, restart the unit, the duration of continuous turning operation shall be > 4hours.

1.7.6 If the initial steam temperature rises or lowers by over 50 within 10 min in start-up, it is℃ required to trip to shut down the turbine immediately.

1.7.7 During turbine speed up, if it is required to hold the speed of turbine, press the button

“HOLD” on DEH control panel. If the turbine is within the range of resonance speed, reduce the speed quickly to below the range of resonance speed and then hold it.

1.7.8 Rotor eccentricity: as the turbine speed is lower than 600r/min, monitor the rotor eccentricity which value shall be <0.076mm, turbine impulsing is not permitted as the rotor eccentricity reaches this value.

1.7.9 Vibration: when the speed reaches over 600r/min, monitor the bearing vibration. It can be regarded as qualified if bearing vibration ≯0.076mm. When the speed is lower than 1300r/min, it shall be regarded as qualified if pad vibration ≯0.03mm, it is necessary to trip to shut down the turbine in excess of 0.03mm. It is necessary to trip to shut down the turbine as the pad vibration exceeds 0.1mm over critical speed (or vibration increases suddenly with abnormal noise if not up to 0.05mm).

1.7.10 Differential expansion:

Positive differential expansion of HP & MP cylinder must not exceed +8mm, and it is necessary to shut down the unit immediately if so; negative differential expansion of HP & MP cylinder must not be less than -3mm and it is necessary to shut down the turbine immediately if up to -3mm; in

differential expansion alarm, and shut down the turbine as up to the shutdown value.

1.7.11 Absolute expansion of cylinder:

In start-up, pay attention to monitoring the absolute expansion of cylinder and compare with the same in the first start-up to prevent cylinder expansion from being obstructed, cylinder shall expands continuously with jamming, if expansion is abnormal, it is required to reinforce warming up, find out and remove the cause.

1.7.12 Differential temperature between upper and lower part of the cylinder: must not be more than 50 .℃

1.7.13 Axial displacement: must not exceed ±1mm. Shut down the turbine as up to ±1.2mm.

1.7.14 LP cylinder exhaust temperature: must not exceed 80℃ (alarm value), shut down the turbine as up to 121℃.

1.7.15 Metal temperature and return oil temperature of all bearings:

(1) Normally return oil temperature of all bearings shall be below 75℃; shut down the turbine as up to 80℃;

(2) Outlet oil temperature of oil cooler is within 38℃~42 ;℃

(3) Metal temperature of journal bearing ＃1~3 shall be below 107℃; shut down the turbine as up to 113℃; the metal temperature of journal bearing ＃ 4~5 shall be below 75℃, shut down the turbine as up to 80℃;

(4) Metal temperature of thrust bearing shall not be higher than 99 ; shut down the turbine℃ immediately as up to 107 ;℃

(5) Lubricating oil pressure is within 0.09~0.15Mpa.

1.7.16 Before the unit impulsing, adjust the initial and reheat steam parameters to meet the start-up requirements by bypass, generally these is no need to adjust the parameters in the process of unit speed up so as not to affect the rotating speed. After the unit paralleling in, check if the automatic control of bypass is normal and pay attention to that the tracking of attemperating water shall be normal; the adjustment of the opening extent of HP & LP bypass shall be based on the need of boiler to prevent too acute oscillation of MP governing valve as a result of too high steam pressure of boil side and too large opening of bypass, at the same time pay attention to the pressure difference before and after HP exhaust steam check valve to prevent it from being closed and causing chocking.

1.7.17 Strictly monitor the water level of HP & LP heater, deaerator and condenser in the process of start-up.

1.7.18 Temperature rise & decrease rate

Name Temperature rise rate Temperature

decrease rate Temperature of initial steam <2~2.5 /min℃ <1.5 /min℃

Temperature of reheat steam <3~3.5 /min℃ <2.5 /min℃ Outer wall of initial and reheat steam pipe 8℃/min

Outer wall of steam valve 4~6℃/min

Flange wall of cylinder 2~2.5℃/min

1.7.19 Temperature difference

Name Unit In temperature

rise

In temperature decrease Temperature difference between upper

and lower part wall of HP & MP outer cylinder stator carrier

℃ <30

Temperature difference between upper and lower par of HP & MP outer cylinder and flange

℃ <50 <40

Temperature difference between upper and lower part of HP & MP outer cylinder

℃ <50

Temperature difference between initial

steam and reheat steam ℃ 40~70 <40

Temperature difference between left

and right main reheat steam pipe ℃ <17