Coupling primary air heat exchange and flue gas waste heat graded utilization device and method

Abstract

The invention discloses a coupling primary air heat exchange and flue gas waste heat graded utilization device and method, and aims to utilize flue gas waste heat in a multi-grade mode. The device comprises a main body graded utilization path and a bypass anti-leakage path. According to the bypass anti-leakage path, a primary air fan is independently provided with a bypass heat exchanger, and theproblem of primary air leakage of a rotary air preheater is solved. The main body graded utilization path adopts multi-grade heat exchange cooling, the first grade is gas-gas heat exchange, and a low-temperature gas-gas plate heat exchanger is adopted to heat cold air into first-grade hot air by utilizing low-temperature flue gas in front of a dust remover; the second grade is gas-gas heat exchange, and an original primary air bin of the rotary air preheater is used for heating the first-grade hot air to form second-grade hot air; the third grade is gas-water heat exchange, and the second-grade hot air forms third-grade hot air after heating supplied water; the fourth grade is gas-water heat exchange, and the third-grade hot air forms fourth-grade hot air after heating condensed water; oneway of the fourth-grade hot air is conveyed to an inlet of a boiler air feeder to be mixed with the cold air and enters a boiler system; and the other way of the fourth-grade hot air is conveyed to an inlet of the primary air fan to be converged with the cold air, and cold end corrosion of equipment is avoided.

Description

technical field [0001] The invention belongs to the technical field of flue gas waste heat energy-saving and efficiency-improving transformation, and specifically relates to a device and method for coupling primary air heat exchange and flue gas waste heat graded utilization. Background technique [0002] The three-chamber rotary air preheater has the advantages of compact structure, convenient layout, flexible adjustment, and high thermal efficiency. Most of the large-capacity thermal power units in the world use this type of air preheater. Usually, one boiler is equipped with two primary fans. . Due to its high pressure, the air leakage rate of the primary air in the three-compartment air preheater is much higher than that of the entire preheater; the air leakage rate of a normal air preheater is about 6-8%, and the air leakage rate of the primary air The amount accounts for 70% to 80% of the total air leakage of the air preheater; thus causing a huge waste of energy cons...

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Problems solved by technology

[0006] The purpose of the present invention is to provide a device and method for coupling primary air heat exchange and flue gas residual heat classification utilization, to solve the technical problem that the existing three-compartment rotary air preheater inevitably causes serious air leakage of the air preheater, especially serious primary air leakage. And the exhaust gas temperature of some boilers exceeds the design value, and the low-temperature economizer is easy to block and corrode, etc.

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