Flue-gas and air system and flow guide device, of flue-gas and air system, at cold secondary air inlet of air preheater

Abstract

The invention discloses a flow guide device at a cold secondary air inlet of an air preheater. The flow guide device is used for a thermal power plant and comprises a first connecting device which is used for being connected with an air feeder and has a certain dispersion angle. The outlet end of the first connecting device is circular. The flow guide device further comprises a flow dividing piece, bent pipes and square circular sections. The flow dividing piece is used for flow dividing and comprises a plurality of circular air pipes, and the inlet end of the flow dividing piece is connected with the outlet end of the first connecting device. The bent pipes are connected with the outlet ends of the circular air pipes of the flow dividing piece, and the number of the bent pipes is equal to the number of the circular air pipes of the flow dividing piece. The square circular sections are connected with the outlet ends of the bent pipes, and the number of the square circular sections is equal to the number of the bent pipes. According to the flow guide device, an original circular air pipe is changed into the multiple circular air pipes through the flow dividing piece, the evenness of air flow at the cold secondary air inlet of the air preheater is improved accordingly, and the heat exchange effect of the air preheater is improved accordingly. The invention further discloses a flue-gas and air system.

Description

Technical field [0001] The present invention relates to the technical field of cooling, in particular to a flow guide device for the cold secondary air inlet of an air preheater. The present invention also relates to a flue gas system including the guide device of the cold secondary air inlet of the air preheater. Background technique [0002] In the flue gas system of thermal power plants, the boiler air preheater is an important device that uses the flue gas heat at the tail of the boiler to heat the air. The air preheater uses the heat in the flue gas to heat the air to increase the air temperature and reduce the exhaust gas temperature, which not only reduces the exhaust smoke loss of the boiler, but also sends the air into the furnace after being heated, so that the fuel in the furnace ignites quickly , The combustion is strong and complete, thus reducing the degree of fuel loss. Therefore, the effect of heat exchange between flue gas and air in the boiler air preheater wi...

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Problems solved by technology

For the conventional circular cold secondary air duct, the size of the cold secondary air duct 2 is relatively large. When a slow-turning elbow is used, the distance from the air flow to the inlet of the air preheater after passing through the elbow is relatively short, and the air flow will Deviated to the outside of the elbow, resulting in uneven distribution of the airflow entering the air preheater; and because the distance between the air duct behind the 90° elbow and the inlet of the air preheater is too short, the diffuser pipe in the flow guide device cannot meet the requirements of the diffuser angle. Less than 20°required

In the scheme of the circular cold secondary air duct, the divergence angle of the square and round joints behind the 90° elbow is about 40°, which not only increases the local resistance when the airflow diffuses, but also makes the airflow too late to diffuse and is concentrated in the air preheating area. Central area of ​​the heater connection, resulting in uneven distribution of airflow into the air preheater

[0007] For the uneven distribution of the above-mentioned air flow when it enters the air preheater, due to the structural characteristics of the flow guide device with a circular cold secondary air duct, it is impossible to set a guide plate in the circular elbow to guide the flow Therefore, the uneven distribution of the air flow at the cold secondary air inlet of the air preheater cannot be solved

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