Handling Interruptions in Coal Feeding to CFB Boilers: A Comprehensive Guide for Efficiency and Safety

The critical process of coal feeding to Circulating Fluidized Bed (CFB) boilers is essential for maintaining stable steam production, furnace pressure, and overall boiler efficiency. Any interruption in the coal feeding process can lead to a rapid drop in furnace temperature and pressure, as well as safety issues such as turbine trip and unexpected shutdowns. Understanding how to handle these interruptions effectively is crucial for the continuous operation and reliability of CFB boilers.

Immediate Actions Upon Interruption

The immediate steps to take when coal feeding to the CFB boiler is interrupted should be swift and well-coordinated to prevent potential damage to the boiler and its associated equipment.

Shut Down the Faulty Coal Feeder: Firstly, the faulty coal feeder should be shut down immediately. This action prevents further damage and allows for a detailed investigation into the root cause of the issue. Only after identifying and addressing the fault should the coal feeder be restored to operation.

Sealing Air Adjustment: If the interruption is due to a coal feeder failure, the sealing air should be appropriately increased to prevent flue gas from flowing back and igniting the coal feeder. This measure is crucial in preventing further damage and ensuring safety.

Adjustments and Monitoring

As the faulty coal feeder is being addressed, adjustments and continuous monitoring of the boiler's performance are necessary to maintain stable combustion and boiler operations.

Adjust Other Coal Feeders: According to the changes in bed temperature and steam flow, adjustments should be made in a timely manner to maintain a stable combustion environment. This includes checking the load, bed temperature, flue gas temperature, and steam temperature to ensure that the coal volume in other coal feeders is appropriately adjusted.

Discharge Blockages: Timely cleaning of blockages is essential to prevent further disruptions. Any blockages in the coal supply system should be removed to ensure a smooth and uninterrupted flow of coal.

Restarting the Coal Feeder

When the coal feeder needs to be restarted after an interruption, it is vital to proceed with caution to avoid further issues. The following guidelines should be followed:

Slow Speed Increase: When restarting the coal feeder, the speed should be increased gradually to ensure that the system can stabilize and maintain optimal performance. This gradual increase allows for any potential issues to be detected early and addressed promptly.

Preventive Measures

To prevent interruptions in coal feeding and maintain the efficiency and safety of CFB boilers, the following preventive measures should be implemented:

Timely Coal Replenishment: Regularly check the coal bunker and ensure that it is adequately replenished to prevent any interruptions caused by an empty bunker. This practice ensures a continuous supply of coal and minimizes the risk of boiler shutdowns.

Load-Based Adjustments: Depending on the current load and conditions, the coal volume in other coal feeders on the adjacent side should be appropriately increased to maintain a stable combustion process. Efforts should be made to keep the coal volume balanced on both sides to ensure the boiler runs normally.

Optimize Steam Temperature: Careful monitoring of the steam temperature is necessary to avoid excessive cooling. When the steam temperature drops below a certain threshold, the desuperheating water should be turned off to prevent the main steam temperature from becoming too low.

Handle Low Bed Temperature: If the bed temperature is low, appropriate steps should be taken to address this condition according to the specific requirements and guidelines.

Electrical Failure Management: In the event of an electrical failure that causes all coal feeding to stop, immediate action should be taken to reduce the air volume. This action will help manage the situation effectively and prevent further damage to the boiler and related systems.

In conclusion, handling interruptions in coal feeding to CFB boilers requires a combination of immediate and preventive measures, ensuring that the boiler continues to operate efficiently and safely. By following the guidelines provided in this article, operators can minimize the risks associated with coal feeding interruptions and maintain the optimal performance of their CFB boilers.