Boiler system and power failure protection method thereof

Abstract

The invention discloses a boiler system and a power failure protection method thereof. The power failure protection method comprises the following steps that small-displacement discharge valves and aninterlocking protection control logic of the small-displacement discharge valves are arranged at the boiler system, when an emergency power failure accident occurs and the main steam pressure reachesan opening pressure value or the water cooling wall outlet working medium temperature reaches an upper limit value, the small-displacement discharge valves are automatically opened; at the moment, ifthe main steam pressure reaches the set pressure of a PCV valve, the PCV valve is manually operated to prevent the PCV valve from being opened; the main steam pressure is continuously reduced throughsteam discharge; when the main steam pressure is reduced to the re-seating pressure and the water cooling wall working medium outlet temperature is lower than the set upper limit, the small-displacement discharge valves are automatically closed; and the above opening and closing operation are continued until the power supply is restored. The total rated discharge amount of the discharge valves is1%-6% of the boiler evaporation amount; and according to the boiler system and the power failure protection method thereof, through opening and re-seating of the small-displacement protection discharge valves, a working medium in a water cooling wall of a boiler is discharged intermittently, the pressure in the water cooling wall and the temperature of the pipe wall are controlled so that the safety of the water cooling wall can be ensured within the relatively long time.

Description

technical field [0001] The invention relates to a boiler system and a power-off protection method thereof, belonging to the technical field of boilers. Background technique [0002] Due to the characteristics of its own structure, the circulating fluidized bed (CFB) boiler has a large amount of high-temperature bed material in the main circulation loop of the boiler during operation. , Therefore, when an emergency power failure occurs in a power plant, the danger caused by the thermal inertia of bed materials and refractory materials may be even greater than that of pulverized coal boilers. Since the steam-water system of the supercritical CFB unit adopts a DC type, when an emergency power failure occurs, the main feed water pump of the boiler will stop running, resulting in water supply interruption. In addition, the boiler primary fan, secondary fan, induced draft fan and coal feeder will also be shut down at the same time. At this time, although the combustion in the fu...

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Problems solved by technology

In addition to the huge initial investment, during the normal production process of the power plant, the system needs to be tested regularly to ensure the reliability and speed of its operation in case of accidents, and the operation and maintenance costs are also high

In contrast, the probability of an emergency power failure in a power plant is very low, so it is difficult for the emergency water supply system to come in handy during its entire service life.

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