Coal feeder, coal feeding system and circulating fluidized bed boiler

Abstract

The invention discloses a coal feeder which comprises a bellows (1), a first coal delivery pipe (2) and a second coal delivery pipe (3), wherein the bellows (1) is arranged around the first coal delivery pipe, two ends of the bellows are respectively connected with the first coal delivery pipe and the second coal delivery pipe, an air inlet (4) and an air outlet (5) are arranged on the bellows, the air outlet is communicated with the second coal delivery pipe; a part (6) of the bellows, connected with the air outlet, is in a frustum shape; and the cross sectional area of the frustum-shaped part is gradually reduced from a direction away from the air outlet to a direction close to the air outlet. In addition, the invention also discloses a coal feeding system and a circulating fluidized bed boiler, wherein the coal feeding system comprises the coal feeder and is used for the circulating fluidized bed boiler. According to the coal feeder provided by the invention, a tapered gradually-contracted jet-type air channel is formed by the frustum-shaped part, so as to enable the coal feeding system to run in a negative pressure state and effectively prevent hot smoke in a hearth from rushing back into the coal feeding system along a material return leg.

Description

technical field [0001] The invention relates to the field of boilers, in particular to a coal feeder and a coal feeding system for a circulating fluidized bed boiler including the coal feeder and a circulating fluidized bed boiler. Background technique [0002] With the continuous maturity and progress of circulating fluidized bed combustion technology and the further improvement of human environmental protection awareness, circulating fluidized bed boilers have gradually been widely used. The coal feeding system of the circulating fluidized bed boiler mainly adopts two coal feeding methods: one is the coal feeding method of the back wall feeder, and the other is the front wall coal feeding method. The working process of the coal feeding method of the back wall feeder is as follows: the coal from the raw coal bunker passes through the belt coal feeder and the scraper coal feeder in turn, and enters the coal falling pipe through the sliding door, and then the coal passing thr...

AI Technical Summary

Problems solved by technology

Since the coal-spreading air can only flow along the pipe wall of the second coal delivery pipe 3, the coal-spreading air cannot compete with the hot flue gas in the furnace, and it is easy to cause the hot flue gas in the furnace to recoil into the coal feeding system along the return leg. Local combustion occurs after mixing with coal and circulating ash near the coal burner, resulting in coking of the return leg, causing the coal drop pipe and even the scraper coal feeder to burn red

Due to the frequent burning of the coal falling pipe, it causes local deformation and coking of the coal falling pipe, which leads to poor coal falling

In addition, because the coal drop pipe and the scraper coal feeder burn red, the sliding door and the scraper coal feeder are deformed, thereby reducing the tightness of the coal feeding system, and the looseness of the coal feeding system will aggravate the heat in the furnace. The backflow of flue gas leads to further deterioration of the situation and forms a vicious circle, which affects the safe and stable operation of the boiler

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