What should be done before relighting a pulverized coal-fired boiler after a flame failure?

Before relighting a pulverized coal-fired boiler after a flame failure, regulating the airflow to approximately 10% and waiting a specified period, like 5 minutes, is essential for a few key reasons.

First, managing the airflow helps to ensure that there is not an excessive mixture of air and fuel in the furnace when the ignition is restarted. Too much air can cause dilution of the fuel-air mixture, making it difficult to achieve proper ignition, whereas too little can lead to incomplete combustion and the potential for harmful emissions.

Additionally, the waiting period allows for any residual unburned fuel and combustion by-products to be cleared from the burner and combustion chamber. This improves safety by minimizing the risk of explosions or flare-ups due to trapped unburned fuel. By carefully controlling the airflow and timing before attempting to relight the burner, operators can promote a safer and more efficient combustion process.

In contrast, adjusting pressure to maximum settings or closing all vents may lead to unsafe operating conditions or create environments that are not conducive to stable ignition. Increasing the fuel supply without first ensuring safe conditions could lead to a dangerous build-up of fuel, exacerbating the risk of flare-ups or explosions during relighting. Therefore, proper air regulation and waiting period are crucial components