A device and method for reducing high-temperature corrosion of power plant boilers by utilizing waste heat of flue gas

Abstract

The invention discloses a device and a method for reducing high-temperature corrosion of a power station boiler by use of waste heat of flue gas. The device is additionally provided with a flue gas-air heat exchanger, an indirect-type air preheater, a Roots blower, a corresponding flue gas pipeline and a corresponding air pipeline. The method has the following flow path: one part of flue gas enters the flue gas-air heat exchanger before the flue gas enters the air preheater, the other part of the flue gas enters the air preheater to heat primary air and secondary air, the flue gas exhausted from the flue gas-air heat exchanger enters a gas flue at the outlet of the air preheater, and two flows of the flue gas are mixed and enter the indirect type air preheater; the indirect type air preheater is composed of a flue gas-air heat exchanger and an air-oil heat exchanger and utilizes conduction oil as a medium to achieve heat exchange of flue gas and air; the heated air in the flue gas-air heat exchanger, used as combustion air, enters a hearth from a side wall of a boiler burner so as to ensure that an oxidizing atmosphere is formed in a side wall combustion zone, and high temperature corrosion of a water cooled wall of the side wall is reduced or alleviated.

Description

technical field [0001] The invention belongs to the field of anti-corrosion of power plant boilers, and relates to a device and method for reducing high-temperature corrosion of power plant boilers by using waste heat of flue gas. Background technique [0002] Under low temperature conditions, the Fe in the water wall tubes will be oxidized, but the speed is very slow, and the oxide is dense and stable iron oxide, forming a protective layer to prevent further oxidation of Fe. Metallic iron oxides may have different structures, where Fe 2 o 3 Relatively stable and tightly combined with the tube; magnetic iron oxide Fe 3 o 4 (FeO·Fe 2 o 3 ) is slightly inferior, and the FeO in it is relatively loose and easy to fall off. Generally speaking, when the pipe temperature is below 300°C, the corrosion rate is very low. [0003] The high-temperature corrosion of the furnace water-cooled wall is that under high-temperature conditions, when the corrosive medium produced by the c...

AI Technical Summary

Problems solved by technology

Therefore, when the primary wind speed is high, the primary wind on the front and rear walls will collide with each other, causing the pulverized coal airflow to rush to the water-cooled wall of the side wall, and the pulverized coal will burn near the water-cooled wall of the side wall, and the temperature will be higher and may wash the water-cooled wall. Causes high-temperature corrosion of the water wall of the side wall

[0005] Reducing the speed of the primary air is conducive to the stability of pulverized coal combustion in the furnace, and at the same time can slightly alleviate the high-temperature corrosion of the walls on both sides, but it cannot fundamentally solve the problem of high-temperature corrosion of the furnace

Increasing the swirl intensity of the internal secondary air is beneficial to the early ignition and stable combustion of pulverized coal, while increasing the volume of internal secondary air will lead to delayed ignition and poor burnout rate of pulverized coal

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