Equal-bed pressure cold slag fluidized bed of circulating fluidized bed boiler and operation method thereof

Abstract

The invention discloses an equal-bed pressure cold slag fluidized bed of a circulating fluidized bed boiler and an operation method thereof. The equal-bed pressure cold slag fluidized bed comprises a directional hood 1, a primary cold air chamber 2, a bed 3, a rectangular shell 4, a warm air pipe 5, a water cooling header 6, water cooled tube bundles 7, a boiler reject valve 8, a cold slag fluidized bed reject valve 9 and a cold slag fluidized bed reject tube 10. In the installation of the equal-bed pressure cold slag fluidized bed, the cold slag fluidized bed 3 is lower than a boiler fluidized bed by 150mm, and a plurality of rows of the water cooled tube bundles 7 are embedded in a material layer on the cold slag fluidized bed, so that the full heat exchange between water and boiler slag can be realized, and the slag can be cooled to be at a temperature below 100 DEG C. The water cooling header 6 uniformly supplies water to the water cooled tube bundles 7. The operation method is as follows: firstly, before the boiler is started, bed material is matted as thick as 350mm on the cold slag fluidized bed, and particle size of the bed material is smaller than 8mm; and secondly, as a slag discharging method at fixed period with higher frequentness is adopted, when the slag on the cold slag fluidized bed is cooled to be at the temperature of 100 DEG C, the slag can be discharged, and when differential pressure of the material layer of the clod slag fluidized bed reaches 3500Pa, the slag discharging door of the cold slag fluidized bed is closed, and then a boiler slag discharging door is opened.

Description

technical field [0001] The invention relates to a circulating fluidized bed boiler, in particular to an iso-bed pressurized slag fluidized bed of a circulating fluidized bed boiler and an operation method thereof. Background technique [0002] my country is currently the country that uses the most circulating fluidized bed boilers (CFB boilers) in power plants in the world. There are more than 3,000 large and small circulating fluidized bed power plant boilers in operation, including large circulating fluidized bed power plant boilers with a capacity of 410t / h or more. There are more than 140 sets, and there are more than 20 sets of large-scale circulating fluidized bed power plant boilers above 1025t / h (more than 50 sets are under construction). [0003] The circulating fluidized bed boiler of the power station is equipped with a slag outlet with an inner diameter of 200mm-300mm at the bottom of the furnace. The slag discharge temperature is about 900°C and the pressure is a...

AI Technical Summary

Problems solved by technology

[0006] 2. Slag particle size requirements are strict

When the slag particle size is large and the amount is too much, it is easy to accumulate and it is difficult to discharge to the next room.

[0007] 3. The middle partition wall with a height of more than two meters (wrap around wall type, jump wall type) is easy to make slag discharge difficult

As a result, the flow speed of the slag is very fast, the impact on the wind cap is intensified, and the wind cap is seriously worn

[0009] 5. In actual production, it is easy to increase the combustibles in the slag discharged from the boiler. At this time, it is easy to cause secondary combustion in one room, resulting in heat accumulation, coking, and then blocking the slag cooler, which finally makes the boiler unable to discharge slag. forced shutdown

The continuous operation time of the boiler is very short due to the high frequency of clogging of the slag cooler

[0010] 6. Poor adaptability to coal quality, when the amount of slag produced by boilers with poor coal quality is also greatly increased, the frequency of slag cooler blockage is also high

[0016] 1. There is almost no air cooling, the fine ash in the bottom slag cannot be effectively recovered, and the unburned carbon particles cannot be returned to the furnace, and the content of fly ash and bottom slag combustibles is high

[0017] 2. The water consumption is very large, and the steam extraction capacity of the steam turbine must be squeezed out, which will reduce the thermal efficiency of the whole plant

[0018] 3. Due to the existence of rotating parts, the drum slag cooler limits its service life

Parts are heavily worn

[0019] 4. Air cooling cannot guarantee output and cooling effect for coal-fired coal with extremely high ash content (ash content>70%), and the large-scale is limited and limited by the site space layout of the power plant. At present, it is very difficult to reach 20t / h

[0020] Due to the above shortcomings of the drum slag cooler, people have come back to study and improve the fluidized air-water slag cooler, but the early three-storey bypass air-water combined slag cooler cannot be used

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