Hearth structure of circulating fluidized bed boiler of 3rd-stage cyclone separator

Abstract

A hearth structure of a circulating fluidized bed boiler of a 3rd-stage cyclone separator relates to a hearth water-cooling screen arrangement of the circulating fluidized bed boiler of the 3rd-stage cyclone separator. Water-cooling screens with equal width are respectively and vertically arranged at one third position and two thirds position in width direction of the rear wall of a hearth, a water-cooling screen is vertically arranged in the middle position in the width direction of the front wall of the hearth and has a membrane type water-cooling wall structure. Under the action of three cyclone separators and the water-cooling screens on the rear wall, three relatively independently granule massing backmixing regions are formed in the hearth. According to the invention, through width of a series of water-cooling screens, area of water-cooling heating surfaces around the three regions is equal, and the temperature deviation in the width direction of wall-cooling walls of the hearth can be well reduced, thus being beneficial to safety running of the boiler.

Description

technical field [0001] The invention relates to a circulating fluidized bed boiler, in particular to an arrangement structure of a furnace water cooling screen of a circulating fluidized bed boiler with three cyclone separators. Background technique [0002] Circulating fluidized bed (CFB) combustion is recognized as one of the most promising clean coal combustion technologies. With the advancement of CFB combustion technology, CFB boilers are also developing in the direction of large-scale. [0003] In the process of large-scale CFB boilers, the cross-sectional area of ​​the furnace increases accordingly, and the size of the cyclone separator also increases. The separators are arranged symmetrically. Among them, the three-separator arrangement is widely used in large CFB boilers of 200MW ~ 300MW, and the overall layout schematic diagram is as follows figure 1 shown. [0004] Due to the asymmetric arrangement of the three-separator structure in the three-separator CFB bo...

AI Technical Summary

Problems solved by technology

[0004] Due to the asymmetric layout of the three-separator structure, the separators on both sides and the middle separator are prone to load distribution deviations, resulting in a decrease in the efficiency of the separators and even affecting the efficiency of the entire boiler.

Considering the penetrating ability of the secondary air, the width-depth ratio of the three-separator CFB boiler furnace is relatively large, generally around 3, which makes the area of ​​the water-cooled heating surface around the heating space on both sides of the furnace much larger than the middle part, resulting in the front and rear of the furnace. The phenomenon that the temperature in the middle part of the width direction of the wall water wall is high and the temperature at both ends is low is not conducive to the safe operation of the boiler

[0005] In the existing three-separator CFB boilers, in order to solve the load distribution deviation of the separators, some boilers adopt the water-cooled partition wall design: a water-cooled partition wall parallel to the side walls is inserted between the separator in the middle of the furnace and the separators on both sides. There are balance holes on the water-cooling partition wall, and there is a gap between the water-cooling partition wall and the front and rear walls of the furnace. The furnace is divided into three almost independent spaces, which hinders the horizontal mixing of particles and is not conducive to heat transfer in the furnace; there are also boilers that adopt Two water-cooled screens parallel to the side walls of the furnace are arranged on the rear wall, which are respectively located between the middle separator and the separators on both sides. However, this design still does not solve the problem of uneven temperature distribution of the water-cooled walls of the front and rear walls of the furnace along the width of the furnace.

Images