Circulation fluidized bed boiler having compact type external dual fluidized bed heat exchanger

Abstract

The present invention discloses a circulation fluidized bed boiler having a compact type external dual fluidized bed heat exchanger, and relates to a large-scale fluidized bed technology. The circulation fluidized bed boiler comprises a wind chamber for providing fluidized wind, a hearth, a cyclone separator connected with a flue gas outlet on the upper part of the hearth, and an external dual fluidized bed heat exchanger arranged inside a hot material circulation loop, wherein the external dual fluidized bed heat exchanger comprises a solid particle outer circulation channel, a solid particle inner circulation channel, an outer circulation fluidized bed heat exchange chamber and an inner circulation fluidized bed heat exchange chamber, and various wind chambers of the external dual fluidized bed heat exchanger and the wind chamber of the hearth are closely arranged in parallel. According to the circulation fluidized bed boiler having the compact type external dual fluidized bed heat exchanger in the present invention, heat of a large amount of high temperature adherence particle flow in the dense phase region of the hearth is adopted so as to substantially increase heat exchange capacity of the external dual fluidized bed heat exchanger under different loads, solve problems of bed temperature stability and steam temperature stability under a low load, achieve independent adjustment and control according to requirements, and meet steam parameter requirements with a high level.

Description

technical field [0001] The invention relates to circulating fluidized bed technology, especially large-scale circulating fluidized bed boiler technology. Background technique [0002] With the increase of circulating fluidized bed boiler capacity, the unbalanced growth of heat release and heat absorption will lead to the layout of the heating surface. In order to achieve a harmonious and balanced development of heat release and heat absorption, and to control the temperature of the main circulation loop within the normal range, the current effective method is to arrange external heat exchangers (Fluid Bed Heat Exchangers, FBHE) outside the furnace. The installed heat exchanger increases the means of operation adjustment of bed temperature and steam temperature, making it easier for the boiler to adapt to the requirements of variable load conditions. The external heat exchangers used by Lurgi and Alstom use the ash control valve to adjust the amount of circulating ash enteri...

AI Technical Summary

Problems solved by technology

The external heat exchangers used by Lurgi and Alstom use the ash control valve to adjust the amount of circulating ash entering the external heat exchanger and directly returning to the furnace, so as to achieve the purpose of adjusting the bed temperature and steam temperature, but the processing accuracy of the ash control valve High requirements, mainly rely on imports, and the price is expensive, which brings certain difficulties to the maintenance and promotion of external heat exchangers

Chinese patent CN00238546.5 discloses an external circulation compact shunt ash return heat exchanger applied to a large circulating fluidized bed boiler. The ratio between the high temperature ash return and the low temperature ash return is adjusted by adjusting the fluidization air volume. The entire heat exchanger has no mechanical moving parts, which simplifies operation and maintenance, but the heat exchanger only uses an external circulation fluidized bed heat exchanger, and the demand for higher steam parameter levels is limited to a certain extent

[0003] When boiler steam parameters need to reach a higher parameter level, such as supercritical parameter 460MW (27.5MPa / 560℃ / 580℃) or ultra-supercritical parameter 800MW (30.9MPa / 604℃ / 621℃), if the conventional A single external external circulating fluidized bed heat exchanger can no longer meet the requirements of high steam parameter levels. At this time, it is necessary to design a new type of external fluidized bed heat exchanger to provide high enough heat exchange capacity to ensure high steam parameter levels needs

International patent WO2007 / 128883 discloses a fluidized bed heat exchanger for a circulating fluidized bed boiler and a circulating fluidized bed boiler with a fluidized bed heat exchanger, two upper and lower heat exchangers connected in series in the main circulation loop The superheater and reheater are arranged in the chamber, and the heat of internal and external circulating solid particles is used to obtain higher superheated steam temperature and reheated steam temperature. However, due to the dislocation arrangement of the two heat exchange chambers, the volume of the two heat exchange chambers is too large, which puts forward more stringent requirements for the layout space of the heat exchange chambers.

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