Multi-stage feedback circulating fluidized bed system with pressure equalizing apparatus

Abstract

A multi-stage feedback circulating fluidized bed system comprises a main bed; a first gas-solid separator; a plurality of back-feeders concatenated in the height direction, the plurality of back-feeders comprising a last-stage back-feeder in a lowest position, accept the last-stage back-feeder, other back-feeders connect to the main bed by an pressure equalizing pipe provided on the top of the ascent stage of the back-feeders or a feedback pipe, at least one pressure equalizing pipe provided with a second gas-solid separator; the pressure equalizing pipe provided with the second gas-solid separator is divided into two segments by the second gas-solid separator, in which one segment is connected with the ascent stage of the back-feeders or the feedback pipe to the inlet of the second gas-solid separator, and the other segment connects the outlet of the second gas-solid separator to the side wall of the main bed, the solid outlet of the second gas-solid separator connecting to a later back-feeder.

Description

technical field [0001] The embodiments of the present invention relate to the field of fluidized bed technology, especially the circulating fluidized bed material circulation system. Background technique [0002] In the circulating fluidized bed material circulation system, when the height of the main bed is very high or the material concentration in the main bed is very high, or because the circulating material in the system is special, such as the material density is low, the formed in the feeder The resistance of the material seal is too small compared to the pressure difference between the bottom of the main bed and the bottom of the gas-solid separator, which is prone to problems such as poor material return in the circulating fluidized bed system and gas backflow in the main bed. Multi-stage return material is used Cascading handles these situations. [0003] Chinese patent CN101219357A discloses a circulating fluidized bed system with multi-stage feeding back. In th...

AI Technical Summary

Problems solved by technology

However, in actual application, due to improper design of the height of the access point, or a large change in the pressure of the main bed due to major changes in the particle properties of the main bed or the operating conditions of the main bed, resulting in large fluctuations in the pressure of the access point, it will affect the system. run

[0005] Taking the double-stage feeder system with two-stage feeder as an example, when the pressure at the access point of the pressure balance pipe is too high, it is difficult for the fluidizing gas in the primary feeder to return to the main bed, and it will flow back from the feeder The gas-solid separator will lead to blow-by of the gas-solid separator, and the separation efficiency will decrease, which will have a great impact on the operation of the system

And when the pressure at the access point is low, the fluidizing gas of the feeder will carry a large amount of material from the pressure balance pipe directly back to the main bed in a short-circuit manner, instead of passing through the final feeder, causing some materials to flow from the feeder to the main bed. Circulation in the circuit composed of pressure balance pipe, gas-solid separator and primary return device, resulting in a significant reduction in the amount of circulating material in the complete cycle composed of the main bed, gas-solid separator and two-stage return device; It will cause the pressure difference of the main bed that needs to be balanced by the final return feeder to rise. Once the material sealing capacity of the final return feeder is exceeded, the gas in the main bed will flow back to the final return feeder, affecting the stability of the system operation. And lead to the increase of the gas flow through the pressure balance pipe of the primary return feeder, and the increase of the amount of solid material carried, resulting in the wear of the pressure balance pipe and shortening the service life of the pressure balance pipe

[0006] Therefore, the pressure balance of the multi-stage return circulating fluidized bed system in the prior art is relatively difficult

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