Vibration Calculation Study Of Large-capacity D-type Boilers

With the development to large capacity and high performance, the boiler's vibration phenomenon becomes more and more common in the process of operating. Under the condition of variable loads, notably, in boiler's inner part, the temperature and pressure vary strongly, which would trigger severe vibration problems of pipe beams. Hence analyzing vibration problems would be very meaningful and extremely applicable.Selecting a D-boiler as study object, this paper deeply discusses structural static strength problem and Karman Vortex Street problem of pipe beams. Firstly, the characteristics of holistic configuration and structural design are related. In the mean time,thermodynamic calculation proceeds under variable working conditions. Then, in the state of 100% normal working condition, the stress is analyzed based on simplified D-boiler pipe beams model by using finite element method. The outcome shows that structural intensity can satisfy the design requirements of pressure component of boiler. Finally, numerical method is used to simulate the flowing status of fumes in D-boiler flue, according to which numerical simulation of Karman vortex shedding frequency in back of convective pipe beams under different working conditions is accomplished. The lift coefficients of convective pipes and spectrum characteristic curves are in turn obtained by using FFT method. The comparative analysis leads to two conclusions:(1) Numerical simulation results of Karman vortex shedding frequency have the same variation tendency with the ones of traditional Karman vortex theory.(2) The speed of fumes goes high, and then Karman vortex shedding frequency can see a slight increase. The height of the part which results in Karman vortex vibration decreases marginally.Compared with conventional empirical calculation, the results of Karman vortex shedding frequency derive from numerical simulation can help accurately justify the induced vibration location of Karman Vortex Street, which is worthwhile to be utilized to guide design works in boiler engineering.