Analysis and treatment of the hottest Bush burning

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Analysis and development of a steam turbine generator set tile burning accident international transfer business processing

our cogeneration steam turbine generator set, model cb/16/7, rated power 6MW, speed 3000r/min, undertakes the dual tasks of steam production and power generation. During the operation, there was a serious tile burning accident when the test machine passed the test, which caused great economic losses to the company

before the accident, the unit operated normally. At the time of the accident, the lubricating oil pressure of the unit suddenly decreased significantly, the electric contact of the pressure gauge was connected, and the generator automatically shed load. However, the turbine did not execute the shutdown command because the magnetic circuit breaker accelerator electromagnet was burned out, resulting in the main throttle valve not being closed, causing the unit to overspeed to 3 070r/min. the operator immediately hit the accelerator of the emergency protector and shut down

II. Equipment damage

1 All eight main thrust pads are burned, and the main thrust disc is severely burned. There are five annular burn grooves on it, with a groove width of 5mm and a groove depth of 0.3~0.4mm. No abnormality is found in the auxiliary thrust pad and auxiliary thrust disc

2.1 #, 2 #, 3 #, 4 # bottom pads have been seriously worn, and the measured top clearance is 0.17~1.75mm

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3 The gas seal blade and gas seal teeth have been worn

III. accident cause analysis

the main reason for this serious Bush burning accident is that the oil pressure suddenly decreases and the turbine runs at high speed under the condition of lack of oil. The reason for the sudden sharp decrease of oil pressure is that the oil resistant rubber pad of the oil pipe replaced in the last overhaul is broken and falls off, there are many 1~5mm black rubber fragments on the oil filter, and the oil pressure control valve is also blocked by fragments, resulting in the blockage of the oil circuit and the sharp decrease of oil pressure

the interlock signal of the instrument fails under high temperature for a long time, the interlock does not work, and the failure of the low oil pressure alarm signal is also an important reason for the accident

IV. treatment

1 Replace all flange gaskets on the oil pipeline with PTFE gaskets

2. Thoroughly clean all oil pipes, oil tanks, oil pumps, oil coolers, oil filters, etc. and then replace the lubricating oil

3. Replace the thrust disc and thrust 13. Working environment: room temperature ~ 45 ℃ pad; Replace 2 #, 3 #, 4 # tiles, scrape and grind 1 # tile; Rotor journal polishing; Adjust the oil baffle oil seal

4. Replace all diaphragm steam seals and front and rear steam seals

5. Replace the magnetic circuit breaker accelerator traction electromagnet and coil

6. Inspect and repair all instrument alarms and interlocks

the unit can be put into normal operation after maintenance

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