It is important to ensure the heating surfacesafety of ultra-supercriticalcirculating fluidized bed (CFB)boiler under electricityfailure. The factors that affect the safety of heating surfaces of a supercritical circulating fluidized bed boiler after a power outage accidentwere analyzed. The transient flow heat transfer calculation model for the boiler heating surfaces was established based on the conservationof mass, momentum, energy, and the heat storage equation of the tube-wall. A program for calculating the dynamic characteristics of theboiler steam water systemwas also developed, which can calculate the variation of the working fluid temperature and tube-wall temperaturewith timeon the heating surface of a boiler under power loss conditions.The result shows that the high-pressure bypass valve needs to exhaust steam at a flow rate of 40% BMCR, with a minimum critical time of 110s for exhaustwhen the safety of the boilerheating surface isensured. Meanwhile, the inlet of the economizer needs to be replenished with water at a flow rate of 140 t/ h. Theworking fluid and tubewall temperature of the water wall, low-temperature superheater, medium temperature superheater, and high-temperature superheater risefirst and then decrease over timeunder this condition. The highest value of tube-wall temperature is lower than the allowable temperaturefor heating surface material. The measures proposed can ensure the safety of heating surfaces of the ultra-supercritical CFB boiler underelectricity failure, solve the problem of overheating of the heating surface after the power loss accident of the CFB boiler, which provides guidance for the operation of the power plant.
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