Flue gas system for unbalance control of flue gas flow

Abstract

The invention relates to a flue gas system for unbalance control of flue gas flow, which comprises an air preheater, an air preheater outlet flue and an air preheater inlet flue which are communicated with the air preheater. N partition boards are arranged in the air preheater inlet flue to partition the air preheater inlet flue into N+1 small flue gas passages in which N adjusting doors are arranged. By adjusting the flue gas flow through the adjusting doors, the flue gas flow flowing through the air preheater forms certain deviation according to the metal temperature variation of a heat storage plate, namely when the metal temperature of the heat storage plate is lower, the heat transfer temperature pressure with the flue gas is larger, and the flue gas flow flowing through the surface of the air preheater is relatively large; and when the metal temperature of the heat storage plate is raised in the flue gas passage along with the rotation of the air preheater, the flue gas flow flowing through the surface of the air preheater is relatively reduced.

Description

technical field [0001] The invention relates to a flue gas system of a power station boiler, in particular to a flue gas system for unbalanced control of the flue gas flow of the power station boiler. Background technique [0002] With the application of rotary air preheater and the capacity development of power plant units, the deviation of flue gas temperature distribution in the outlet flue of air preheater is getting bigger and bigger. Taking a certain 1000MW unit boiler as an example, the upper end of the flue gas channel of the air preheater (according to the rotation direction of the air preheater, the part of the flue gas channel that the rotor first enters from the air side is the upper end, and the part that enters after the upper end is the lower end, the same below) the flue gas at the outlet is the lowest, and its temperature is more than 40°C lower than the lower end of the flue gas channel outlet, and about 20°C lower than the average flue gas temperature. Th...

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Problems solved by technology

[0005] From the point of view of the principle of preventing low-temperature corrosion and ash plugging of the air preheater, the balanced distribution of the flue gas flow in a single flue makes the heat storage plate of the air preheater have the lowest temperature at the uppermost end of the flue gas channel, and the flue gas temperature at the outlet is also the lowest. Lowest, most likely to cause low temperature corrosion and dust blocking

In order to prevent the low-temperature corrosion and ash blocking of the air preheater, it is necessary to ensure that the outlet flue gas temperature at the uppermost end of the flue gas channel of the air preheater is above a certain value of the acid dew point temperature, so that the exhaust gas temperature of the boiler will increase and the thermal efficiency of the boiler will decrease

If the average temperature of the flue gas is controlled below a certain value of its acid dew point temperature, although the exhaust gas temperature of the boiler will be reduced, it will cause low-temperature corrosion and ash blocking of the air preheater

This contradiction cannot be solved in the existing flue gas system

[0006] The essence of the above problems is that the existing single-inlet flue gas channel of the air preheater can only distribute the flue gas flow in a balanced manner, and cannot be adjusted artificially. Therefore, the existing flue gas system and its devices cannot solve the problem of air preheating. The temperature distribution of flue gas at the outlet of the heater is relatively large, and the heat exchange efficiency of the air preheater cannot be improved.

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