Influence Of Steam-side Oxide Scale On Tube Wall Temperature And Temperature Monitoring Of Utility Boiler

With the development of electric power industry, the design parameters of working medium were constantly improved. The efficiency and the economic benefit of boiler unit have been improved. But the development of power plant is also accompanied by a lot of questions. There are a lot of oxide scale discovered in the steam-side of the Tube multiple supercritical power plant units. The main problem is the oxide film’s generation and accumulation in the Tube, which caused the over temperature of the Tube and Tube detonation. Usually the Tube wall temperature measurement points of power plant boiler super heater and reheater are installed above the ceiling of the furnace, which can’t reflect the real temperature of Tube wall. The domestic scholars have done a great deal of research and experiments for furnace wall temperature calculation and monitoring. But there are little analyses for the influence of the oxide film on Tube wall temperature. So, the analysis of the effect of oxide film on Tube wall temperature and the temperature measurement error is necessary, which is also useful for the design and operation of boiler of in coal-fired power plant.In this paper the convention heating surface is selected as the research object. First of all, through numerical simulation and theoretical analysis method, the relationship between the thickness of oxide film and Tube wall temperature was analyzed. If keeping the heat flux of the Tube wall temperature unchanged, the relationship of Tube wall temperature and the oxide film thickness is approximate to linear relationship in the scope of a small thickness change, but when the oxide film thickness keep thickening wall temperature increases exponentially. Considering the actual situation, the analysis of wall temperature change was done, when the oxide scale accumulation in the Tube. At the beginning of the progress, the Tube wall temperature changed quickly, and finally keeping close to the flue gas temperature.At last, through using numerical simulation software, FLUENT, the simulated experiment was conducted about the primary super heater in Daihai power plant. The simulated experiment mainly analyzed the monitoring error of the Tube wall temperature measurement points under different thickness of oxide film. Another analysis about the influence of oxidation film on the temperature response of the Tube wall temperature measurement points was also conducted, when the flue-gas temperature changed.