Discussion on calculation method of natural frequency of flue design in thermal power plant based on temperature field simulation

Abstract

The vibration of the boiler tail flue not only leads to tearing and steam leakage at the welding point between the superheater and manhole, but also makes the acoustic soot blower in the tail flue basically unable to be put into operation, which seriously affects the safe operation of the unit. In order to reduce the size of external reinforcing ribs, the minimum number of internal struts should be used in large section flue. By means of temperature field simulation, the author adds a flow guide device at the junction of the down flue and the horizontal flue to forcibly guide the flue gas to the convection heat exchange area. The simulation results show that the vertical velocity field distribution of the horizontal flue tends to be uniform after adding the diversion device. Measures should be taken to prevent the vibration of the inner strut, such as selecting the inner strut with appropriate specifications; Install fins on the inner strut; Change the natural frequency of the inner strut; Select appropriate flue gas flow rate, etc.