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

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The issues that need to be considered when placing a circulating fluidized bed boiler into pressure-fire standby are as follows: 1) A high material level should be maintained when the boiler is in pressure-fire mode. 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 of the combustible materials in the bed have been completely burned off. At this point, stop supplying air to the furnace and the cold slag chamber, then quickly shut down all fans and close all air dampers 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 fire suppression ； 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. ?