| Excess temperature tube failure is often happened in the reheater system because of high gas temperature, low steam temperature, bad cooling condition and small safety margin. In this paper, the phenomenon of excess temperature tube failure of the 1025t/h boiler of Jin Zhou thermal power plant is analyzed. Checks of thermal calculations with four different unit loads are performed. Wall temperature calculations are also carried out. The results indicate that the wall temperature of #3-#7 reheater is higher than normal, and #4 is the worst. The working life of tube decreased half if the temperature rises about 10℃. The FLUENT software is applied to simulate the temperature and velocity field of furnace. The results show that the main causation of excess temperature is the serious residual rotation of medium rehearter over outlet of furnace. All the theory calculation and numerical simulation are conforming to reality. According to the above analyses, retrofit schedule of the reheater has been made, and put it into practice. Excess temperature tube failure never happened after improvement. |
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