Study On Corrosion And Vibration Of Water- Wall Boiler On A 260t/h Power Plant Boiler

This dissertation mainly studies the urea corrosion of water-wall tube and abnormal vibration of water-wall of the pulverized coal boiler in a 260t/h(60MW) power plant. ANSYS theoretic analysis was executed on the vibration problem, and proposed a corresponding engineering solution, which obtained satisfactory transformation effects and provides universal guidance to similar problems of other power plants.In the dissertation, an introduction was made about the corrosion problem occurred around the urea spray gun after the applying of SNCR/SCR flue gas desulfurization technology in a 260 t/h power plant in Jiangsu Province. In response to this problem, a corrosion test platform was constructed to simulate the corrosion situation and development of water-wall sprayed with urea. At the meantime, a high emissivity nano-ceramics anticorrosive painting was introduced, whose protection effect to the water-wall tube was also studied. Results indicated that the highest corrosion rate appears at 400 ℃ , both higher or lower temperature would inhibit the development of corrosion. The corrosion rate increases with the concentration of urea. The applying of coating could attach the corrosion products Fe2O3 to the surface of basal body and protect it from further corrosion, and the coating itself would not be corroded.For the vibration problem, on-site inspection was performed to analyze the probable reason of the abnormal vibration, which might be the resonance between the vibration induced by combustion in the boiler and the natural vibration of hearth. Primary theoretic analysis was made towards the probable reasons.Meanwhile, this dissertation used ANSYS to promote the accuracy of vibration analysis, and the simplification scheme of the structure of water-wall was also proposed. Numerical simulation towards the transformation scheme was established, from which achieved the simulation results of vibration and used it in the on-site execution of transformation.On the basis of theoretical and numerical simulation analysis, and combined with project experiences, the transformation scheme of water-wall against abnormal vibration was proposed. Updating and transformation was executed according to the scheme, whose results appeared to be favorable. Adding draw bar and hanging the soot blower could reduce the amplitude for at most 79.2%. The satisfying transformation effects also showed the rationality of numerical simulation and the reliability of the results.