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How to prevent boiler coking in power plant

time: 2019-08-19

In March 1993, the unit 1 boiler’s furnace exploded in Beilun port.

The accident had caused disastrous casualties to the power plant, 23 workers were dead, 24workers were injured(8 people were serious injured). After the explosion, 934 cubic meters of ashes had to be cleaned up,RMB7.78million disappeared vanished, The unit was shut down for 132 days and generated 1.4 billion kWh less.

The results show that the main cause of the accident is serious slagging.

With the continuous occurrence of such incidents, higher requirements have been put forward for the safety of boiler design and operation.

Chinese boilers had experienced by technology learning, independent, importation, improving and integrated development in the past years.Currently, we are able to produce a boiler that suits a varieties of coal that burns differently, different type and different pressures.

Even so, the phenomena of boiler coking still exists. When the boiler is coking and the ash builds up, it will decrease the boiler evaporation rate and increase the temperature & flue gas resistance of discharge flue.It will not only worsen the combustion condition, decrease the thermal efficiency of boiler but also cause problems to part of the water cycle, even cause the pipe wall to be burnt out by over heat and shutting down of the boiler. 

This is why boiler decoking agents are still widely used to clean the ashes on the surface of the boiler.

POLYTE®30A boiler decoking agent, It will react in combustion heating after mix with coal.  Control coking, deposition and corrosion of fire side by increasing the melting point and looseness of the ash component, and then promote coal combustion, expand combustion volume, increase heat transfer area and improve thermal efficiency.

POLYTE®30A Boiler Decoking Agent

Applications

A power plant has two boilers manufactured by Harbin Boilers Co.,Ltd, the boiler uses diagonal tangential combustion method and solid slag discharge. The coal type in the operation it's relatively complicated, which is quite different from  the coal type designed for the boiler , in result of a serious coking of the boiler.

Boiler and Main design spec.

Decoking test and result

(1) Coking thickness around fire hole

The setting of the fire hole is essential to observe the coking, we can see parts of the coking inside .

As been shown in the table, after four days of dosing the POLYTE® 30A decoking agent, the thickness of the coke layer around the boiler's fire hole was significantly reduced.

(2) Division panel  effect

Before

After

We can see from the pictures above, Before dose, the division panel  tubes were covered by the coke. After dose the agent, the division panel  tubes are exposed and clearly visible. After dose, the metal temperature of the division panel, the rear and the reheating pre-screen improve significantly.

Conclusion:

After using the POLYTE® 30A decoking agent, the furnace shows a significant decrease in the thickness of the coke, and the division panel tube is exposed, indicating that the POLYTE® 30A decoking effect is remarkable.

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