Method of reducing fly ash carbon content of circulating fluidized bed boiler

Abstract

The invention discloses a method of reducing fly ash carbon content of a circulating fluidized bed boiler, wherein the method comprises the following steps when the circulating fluidized bed boiler comprises a hearth, a cyclone separator, a vertical pipe and a feedback device: 1) mounting a helical feeder on the upper part of the vertical part, and connecting an oxygen-enriched air generator at the air inlet chamber on the bottom part of the feedback device; and 2) when the circulating fluidized bed boiler operates, the helical feeder conveys the fly ash to the upper part of the vertical part, the fly ash enters the feedback device through the vertical pipe, the coke in the fly ash in the feedback device and the oxygen-enriched air generated by the oxygen-enriched air generator generate an oxygen-enriched combustion reaction, in the reaction, the percent by volume of the oxygen in the oxygen-enriched air is controlled to control the combustion temperature of the fly ash, and the fly ash and the flue gas return to the hearth after the reaction. The method disclosed by the invention can be applied on circulating fluidized bed boilers of burning inferior coal, and the method can greatly increase the combustion reaction speed and standing time of the coke in the fly ash in the high temperature region of the circulating fluidized bed boiler and greatly reduce the fly ash carbon content of the circulating fluidized bed boiler.

Description

technical field [0001] The invention relates to the technical field of reducing the carbon content of boiler fly ash, in particular to a method for reducing the carbon content of circulating fluidized bed boiler fly ash. Background technique [0002] Circulating fluidized bed boilers have the outstanding advantages of wide fuel adaptability and low pollutant emissions, so they can be widely used. However, circulating fluidized bed boilers burn low-quality coal, especially low-volatile low-quality coal, and there is a problem of high carbon content in fly ash. The carbon content of fly ash can be as high as 10% to 25%, which reduces boiler efficiency and increases energy loss. , and limit the comprehensive utilization of fly ash. [0003] At present, there are some solutions to the problem of high carbon content in CFB boiler fly ash, which can be referred to the patent - Combustion Method and Device of Fly Ash Bottom Feeding Circulating Fluidized Bed Boiler for Refractory F...

AI Technical Summary

Problems solved by technology

However, circulating fluidized bed boilers burn low-quality coal, especially low-volatile low-quality coal, and there is a problem of high carbon content in fly ash. The carbon content of fly ash can be as high as 10% to 25%, which reduces boiler efficiency and increases energy loss. , and limit the comprehensive utilization of fly ash

[0003] At present, there are some solutions to the problem of high carbon content in CFB boiler fly ash, which can be referred to the patent - Combustion Method and Device of Fly Ash Bottom Feeding Circulating Fluidized Bed Boiler for Refractory Fuel (Patent Application No. 200310106047.8) and Patent - tapered and expanded pipe and ash return pump and fly ash reburning circulating fluidized bed combustion equipment (patent application number is 200710054674.X), the former returns fly ash to the bottom of the dense phase zone of the furnace for combustion, the latter The fly ash is returned to the upper part of the dense phase area for combustion. Both methods are due to the high fluidization wind speed in the furnace, usually 5-7m / s, and the short residence time of the fly ash in the high temperature area of ​​the furnace, which makes the circulation The reduction of carbon content in fluidized bed boiler fly ash is very limited

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