Common Phenomena & Treatment Principles for Damage of Boiler Heating Surface

December 17, 2019

Leakage or blasting sound can be heard in the furnace or flue duct when the heating surface of the boiler is damaged. Although the parameters of the boiler are basically unchanged, the feedwater flow is not normally larger than the main steam flow, the difference of flue gas temperature and steam temperature on both sides of the boiler will increase obviously, and the flue gas temperature on the damaged side of the heating surface will decrease dramatically, causes the combustion in the furnace may be unstable and even cause the boiler to shut down when seriously. The opening of I.D Fan and the current will increase automatically when the furnace negative pressure is put automatically. When the I.D Fan is not automatic, the negative pressure in the furnace will be positive. At this time, large I.D Fan should be opened by hand to maintain the normal negative pressure in the furnace.

When the leakage of the heating surface is not serious, the fuel, feeding water and airflow should be adjusted in time to maintain the normal operation of boiler parameters. Feedwater automation should be change to manual control in time if the operation is abnormal. If necessary, it can also reduce the main steam pressure or the boiler load can be reduced properly, closely monitor the development trend of leakage site, make good accident precaution, give the report to chief engineer, require to apply for scheduling shutdown and make preparations before shutdown.

If the leakage of the heating surface is serious or explodes, lead to the temperature of working fluid to rise sharply, and causes the overheating of the pipe wall serious, and can not maintain the normal operation of the boiler or endanger the people and equipment safety, the furnace should be handled by the manual emergency shutdown. In order to prevent the steam and water erupt from the boiler when shutdown, the I.D Fan should be kept in operation to maintain normal negative pressure in the furnace till the steam in the leaking or blasting place has basically disappeared then stop the I.D Fan. In order to prevent the electric dust collector gather dust, it should immediately stop the electric supply to it, and keep its continuous shake mode. In order to prevent dust blockage in ash hopper, ash in the Cottrell, rotary air preheater and economizer should be exhausted.

In addition, safety measures should be taken near and around the leakage or blasting point (e.g. Economizer Ash hopper) to prevent steam and water from erupting to hurt people.

If the blasting of the heating surface causes the boiler to completely quench or partial quench, it should be treated according to MFT of boiler quench. When the main steam temperature and reheat steam temperature are too high, too low or the deviation between the two sides is too large due to the damage of the heating surface, it should also be dealt with in accordance with the relevant requirements of abnormal steam temperature.

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