【Q&A Question 115】2016.08.13
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【Q&A Question 115】August 13, 2016: What are the signs of a broken turbine blade? The answer key will be available after responding; scoring is based on addressing the key points. There are metallic clanging or knocking sounds inside the cylinder, along with increased vibration.
The turbine vibrates severely; there are noises or impacts inside the turbine, and the last-stage blades have fallen off
The turbine will run idle, damaging the turbine
(1) A sudden noise occurs inside the turbine or inside the condenser； (2) Unit vibration experiences significant changes in both amplitude and phase, and sometimes intense instantaneous shaking occurs. This is caused by blade breakage, loss of rotor balance, or frictional impacts. (3) When the blades are severely damaged, the flow area changes, and under the same load, the steam flow rate, the opening degree of the throttle valve, and the pressure in the monitoring section all change, a phenomenon that is particularly evident in reaction-type units. (4) If a blade falls into the condenser, it usually damages the copper tubes of the condenser. (5) If a blade breaks off at the steam extraction point, it may enter the steam extraction pipeline, causing the steam extraction check valve to stick, or it may enter the heater and damage its tubes, leading to an increase in the water level in the heater. (6) During the shutdown coasting process or when the turbine is being turned, a metallic grinding sound can be heard, and the coasting time decreases. (7) After a rotor blade is lost, its balance condition and axial thrust change, which can sometimes lead to an increase in the temperature of the thrust bearings and the temperature of the oil returning to the bearings.
There are metallic clanging or knocking sounds inside the cylinder, along with increased vibration
The vibration increases, there are abnormal noises, and the exhaust pressure should fluctuate
Signs of turbine blade failure include: 1) A sudden noise occurring inside the turbine or in the condenser. 2) Sudden increase in vibration or shaking of the unit. 3) When the blades are severely damaged, to maintain a constant load, the steam flow rate must be increased, that is, the valve opening degree must be raised. 4) The condenser water level rises, the conductivity of the condensate water increases, and the current drawn by the condensate pump increases. 5) Broken blades entering the extraction steam pipeline cause valve sticking. 6) A metallic rubbing sound can be heard during idle operation and crankshaft rotation. 7) The intermediate pressure increases during operation.
Dynamic balance is disrupted, resulting in first-order harmonic vibration