Method for heating primary air with heat of flue gas bypass of tri-sectional air preheater

Abstract

The invention discloses a method for heating primary air with heat of a flue gas bypass of a tri-sectional air preheater. The method comprises the steps as follows: hot boiler flue gas enters a main hot flue gas path and the hot flue gas bypass through a hot boiler flue gas inlet respectively; the hot boiler flue gas enters a shell-and-tube primary air heat exchanger through the flue gas bypass toheat cold primary air entering the shell-and-tube primary air heat exchanger through a cold primary air inlet, the heated cold primary air becomes hot primary air, and the hot primary air flows out of a hot primary air outlet; the hot boiler flue gas enters a flue gas bin of the tri-sectional air preheater through the main hot flue gas path to heat cold secondary air; the cold secondary air enters a primary air bin and a secondary air bin of the tri-sectional air preheater through a cold secondary air inlet respectively for heating, and the heated cold secondary air flows out of a hot secondary air outlet. With the method, the air leakage rate of the tri-sectional air preheater is reduced, the exhaust gas temperature is reduced, then the boiler efficiency can be improved, and the coal consumption is reduced.

Description

technical field [0001] The invention relates to a method for heating primary air, in particular to a method for heating primary air by using heat from flue gas bypass of a three-part air preheater, and belongs to the technical field of coal-fired boilers. Background technique [0002] The air preheater is one of the important systems of the pulverized coal boiler, which plays the role of reducing the exhaust gas temperature, increasing the temperature of the combustion air, making the fuel easy to ignite, stable combustion and improving combustion efficiency. The air preheater mainly includes three compartments, shell and tube two forms. At present, more than 90% of coal-fired boilers in power stations use three-compartment air preheaters, and the three compartments circulate hot flue gas, primary air and secondary air respectively. For the three-compartment air preheater, there have been two obvious problems that have not been resolved for a long time: on the one hand, the...

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Problems solved by technology

For the three-compartment air preheater, there have been two obvious problems that have not been resolved for a long time: on the one hand, the air leakage rate of the three-compartment air preheater is relatively high, and the air leakage from the primary air chamber to the secondary air chamber The air leakage rate from the secondary air chamber to the flue gas chamber is about 4%, and the air leakage rate from the secondary air chamber to the primary air chamber is about 8%. The air leakage rate is about 8%; on the other hand, the air preheater of the three-part warehouse has relatively large resistance and high coal consumption

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