Undercurrent external heat exchanger of circulating fluidized bed

Abstract

The invention relates to an undercurrent external heat exchanger of a circulating fluidized bed, which comprises a feeding vertical pipe, a feeding chamber, a heat exchanging chamber, a coiled pipe heating surface arranged in the heat exchanging chamber, an inlet header, an outlet header, a first partition wall, a second partition wall, an overflow chamber, an ash returning pipe, and an undercurrent hole; wherein a row of undercurrent holes are arranged at the lower part of the first partition wall between the feeding chamber and the heat exchanging chamber so that both of the upper part and the lower part of the heat exchanging chamber are supplemented by high temperature circulating ash, thus improving the flowing and heat exchanging condition of a dead zone in the heat exchanging chamber; and the upper rand lower temperature gradient of the heating exchanging chamber decreases, which is beneficial to the mixing of the circulating ash; the integral heat exchanging performance of the heat exchanging chamber is enhanced; a walling is arranged next to a side wall; the bend part of the coiled pipe heating surface is buried in the waling, not only bears the support and fixes the coiled pipe and heat exchanger, reduces the vibration of the heat exchanger, but also protects the bend of the heat exchanging surface of the coiled pipe not to be corroded by the circulating ash. The technical solution of the invention is easily realized and beneficial to solve the problems of heat transmission, vibration and abrasion of the external heat exchanger.

Description

technical field [0001] The invention relates to a large circulating fluidized bed boiler, in particular to a circulating fluidized bed boiler with an external heat exchange bed. Background technique [0002] In the process of large-scale circulating fluidized bed boiler, due to the increase of boiler capacity, the ratio of furnace heating surface to volume decreases, it is difficult to balance the arrangement of evaporation heating surface and superheating surface, and it is difficult to control the bed temperature. In the fluidized bed technology, a part of the heating surface in the furnace is moved outside the furnace, and an external heat exchange bed is used. The external bed heat exchanger mainly includes a feed chamber, a heat exchange chamber and an overflow chamber. The serpentine tube heating surface is arranged in the heat exchange chamber. The serpentine tube bundle adopts a suspension structure as a whole, and is connected through the ceiling of the heat exchang...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the serious abrasion and vibration of serpentine tubes on the heat exchange surface of the existing external heat exchange bed and poor heat exchange performance, the present invention proposes an improved submerged flow external heat exchange bed, which improves the heat exchange performance in the heat exchange chamber. The submerged external heat exchange bed protects the elbow of the serpentine tube from the abrasion of circulating ash by changing the fixing method of the heat exchange surface of the serpentine tube; and by improving the flow path of the high-temperature circulating ash, it strengthens the mixing of the circulating ash in the heat exchange chamber, thereby Improve heat transfer performance

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