Analysis of accidents prone to occur to the heating surface of boiler tubes
1. Long-term over-temperature burst tube
Over-temperature refers to metal materials operating on temperatures exceeding the rated temperature. The rated temperature refers to the allowable maximum temperature of the steel during the design life, and can also refer to the rated temperature during operation. As long as one of the above temperatures is exceeded, it is an over-temperature operation.
2. Short-term over-temperature burst tube
Except for improper structural design, the over-temperature explosion of the pipe is mainly caused by overloading operation, improper operation, or blockage of internal organs. Overload operation will generally increase the outlet temperature of the convective superheater, aggravate the phenomenon of over-temperature, and accelerate the creep of the pipe; abnormal start-up will cause drastic changes in combustion, rapid pressure increase, or fire extinguishing in the furnace. Temperature; the clogging of the tube's internal dirt or salt scale will cause poor soda circulation, causing the tube to locally overheat and quickly cause the tube to burst.
3. Tube burst caused by poor material
A broken pipe with a poor material refers to the premature failure of the pipe caused by the wrong use of steel or the use of defective steel.
4. corrosive thermal fatigue crack damage
The steam and moisture layers of the heating surface of the boiler, the steam plug of the economizer tube, the water in the superheater, and the intermittent opening of the temperature and pressure reducing valve, etc., will cause temperature fluctuations, resulting in alternating thermal stress and thermal fatigue cracks. Besides, under the action of corrosive media, fatigue cracks on these pipes are particularly prone to notched areas such as rough surface, scratches, corrosion pits, etc., where the corrosion rate is large, so they are called corrosive thermal fatigue cracks.