Study On Vibration Control Of Boiler Frame Of Coal-Burning Power Plant Subject To Earthquake

As one of the most important facilities in a thermal power plant, the boiler needs an effective performance to resist earthquake, which is mainly provided by the boiler frame. The boiler body with the weight of several thousand tons is suspended on the large plate beam at the top part of the boiler frame through tens of hundreds of hanger rods. In order to limit the later expansion of the boiler body, a few guiding devices are installed in every storey of the boiler frame. These guiding devices firmly connect with the boiler frame and allow the boiler body a vertical expansion only. Subjective to earthquake, the strong seismic force from the boiler body is transmitted to the frame through the guiding device. However, present boiler frames are rather conservatively designed so that they cost a great amount of building materials. Hence, it is necessary to properly deploy devices for energy-dissipation to deduce the vibration of the boiler body and the seismic force taken on by the frame. Besides, this could result in the less cost of building material and the remarkable economic benefits.This thesis introduces the passive control technology into the guiding device of the boiler frame. A new type of guiding device for the boiler frame is proposed and made. The corresponding the test on the shaking table of earthquake simulation and the finite element analysis verify the control effect of the device. The main contents of the thesis are as follows:Firstly, on the base of ensuring the function of the existing guiding device, a new type of guiding device for boiler frame is innovatively designed, which uses the magnet-friction damper and the viscous damper. This new guiding device has the different energy-dissipation functions in two directions, i. e., the viscous energy dissipation is in one direction and the magnet-friction energy-dissipation is in the other direction.Secondly, according to the requirement of the model of the boiler frame for testing on the shaking table, this study designs and makes 8 magnet-friction dampers and 8 viscous dampers. Through testiing their performance, this study obtains the hysteresis characteristic curves of the two types of dampers. The testing results validate their good performance on energy-dissipation.Thirdly, taking the boiler frame of 300MW in Liaoyang Power Plant as the prototype structure, this study designs and makes a 1:1.5 boiler frame model. Then, it conducts the shaking table tests of 6 schemes that the model is installed with the existing guiding device and the new guiding device respectively, which includes 54 case studies. The experimental analysis reveals and verifies the effect of the new guiding device and its arrangement on the energy-dissipation and vibration-reduction of the boiler frame.Fourthly, using the ANSYS software, this study builds the finite element analysis (FEA) model for the frame model. It proves the reliability of the finite element model by comparing the FEA result of the seismic response of the frame model with the existing guiding devices with the corresponding testing result. For the boiler frame model with both the magnet-friction damper and the viscous damper, the FEA result indicates that the new guiding devices have an excellent vibration-control effect, when compared with the testing results.Finally, taking the maximum displacement at the top storey and the maximum displacement between adjacent stories of the boiler frame as the performance criterion, this study fits the functional relationship between the criterion and the parameters in the new guiding device. By adjusting the parameters of the new guiding device to control the displacement of the boiler frame, this technique can meet the requirement of the boiler frame working in earthquake.