What issues need to be considered when a circulating fluidized bed boiler is kept in pressurized hot standby mode?

1. When shutting down the boiler, a high level of fuel should be maintained. First, stop feeding coal, and monitor the oxygen level at the furnace outlet. Once the oxygen level starts to rise, it indicates that the volatiles in the fuel bed have been completely burned. At this point, stop supplying air to the furnace and the slag cooler, then quickly shut down all fans and close all air dampers in order to minimize heat loss inside the furnace. The J-valve fan should continue to operate until the J-valve is cooled below 260°C before it can be stopped. 2. After the boiler is shut down, all furnace doors and air/flue dampers should be sealed to prevent rapid cooling. 3. Close all drain valves, and use the drain valve at the high-temperature superheater outlet header to cool the superheater, in order to prevent overpressure in the boiler. 4. Regularly monitor the rise in bed material temperature after extinguishing the fire ； If the temperature does not rise normally, the cause should be identified and eliminated immediately. 5. If the fire is suppressed for too long, it can be restarted while hot; once the bed temperature rises to 850–900°C, the fire should be suppressed again.

The issues that need to be considered when keeping a circulating fluidized bed boiler in a cooled and standby state are as follows: 1. When cooling the boiler, it is necessary to maintain a high level of fuel in the furnace. First, stop feeding coal, and monitor the oxygen level at the furnace outlet. Once the oxygen level starts to rise, it indicates that the volatiles in the fuel bed have been completely burned out. At this point, stop supplying air to the furnace and the slag cooler, then promptly shut down all fans and close all air dampers in order to minimize heat loss within the furnace. The J-valve fan should continue to operate until the J-valve is cooled below 260°C before it can be stopped. 　　2. After the boiler is shut down, all furnace doors and air/flue dampers should be sealed to prevent rapid cooling. 　　3. Close all drain valves, and use the drain valve at the high-temperature superheater outlet header to cool the superheater, in order to prevent overpressure in the boiler. 　　4. Regularly monitor the rise in bed material temperature after extinguishing the fire ； If the temperature does not rise normally, the cause should be identified and eliminated immediately. 　　5. If the fire is suppressed for too long, it can be restarted while hot; once the bed temperature rises to 850–900°C, the fire should be suppressed again.