Flue gas bypass heat primary air and fed water heating method for trisection air preheater

Abstract

The invention discloses a flue gas bypass heat primary air and fed water feeding method for a trisection air preheater. The primary air and fed water heating method includes the following steps that cold secondary air enters a primary air chamber and a secondary air chamber of the trisection air preheater to be heated through a cold secondary air inlet, and heated cold secondary air is converged and then flows out through a hot secondary air outlet; boiler hot flue gas enters a hot flue gas main way and a hot flue gas bypass through a boiler hot flue gas inlet; the boiler hot flue gas enters afed water heat exchanger and a tube-shell type primary air heat exchanger in sequence through a flue gas bypass to be subjected to heat releasing, and the boiler hot flue gas enters a cold flue gas bypass to become bypass cold flue gas after heat releasing; and fed water flows a water heat exchanger to absorb heat through a water feeding opening and then enters a boiler economizer. By means of the flue gas bypass heat primary air and fed water heating method for the trisection air preheater, cold primary air, cold secondary air and fed water can be heated at the same time, the flue gas heat utilization rate is high, and the problem that the resistance of the trisection air preheater is large is solved.

Description

technical field [0001] The invention relates to a method for heating primary air and water supply, in particular to a method for heating primary air and water supply by utilizing the flue gas bypass heat of an air preheater in a three-segment warehouse, 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...

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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 high resistance and high coal consumption; thirdly, there is currently no scientific method and system for heating the cold primary air and water supply at the same time, and the smoke Gas heat utilization rate is low

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