Three-Dimensional Calculation About The Wall Temperature And Research On Overtemperature And Tube Explosion On The Superheater Of Certain Marine Boiler

Superheater is one important part of Steam boiler setting. Because the mediator working in the superheater are high temperature and high pressure steam, and the heating surfaces are in the high temperature fume area, so the working condition is bad. As a result of this, accidents of overtemperature and tube explosion in the heating surface of superheater often occures , because of many elements in design, manufacture and operation. It is significative for the design and operation of the boiler to simulate the wall-temperature of superheater well and truly.We carried on an investigation into the superheater of certain marine boiler, To reduce the size of the superheater by using reasonable rule on the base of original modle and the stimulant results could reflect the working characteristic of the original superheater, and bulided an three-dimensional geometry modle by software GAMBIT, which was an appropriate characterization of the turbulence flow with heat transfer of steam inside and fume outside, and simulated it by adopting software FLUENT.Three different instances are done in this numerical simulation of the superheater. Through the numerical simulation, the distribution of pressure, flow, temperature, enthalpy, heat flux and the wall-temperature, had been gained, and also various parameters of the steams in the tubes that were intercepted by sections. The simulation results indicated that:1. Because of the Z-superheater the structural characteristics and heat uniformity , the first header steam flowed along the flow direction, the mass flow of steam within the overall increased gradually, but in the corridors of the flue gas pipe thermal efficiency of the flow, vapor flow had been significantly reduced. Flue processes occupied the second half of the width of its distribution steam flow was low intermediate, and high on both sides of the distribution trends.2. Because The static pressure Margin of The middle clapboard on both sides of Superheater was big , the working environment was poor, with changed in the load, it proned to collapse. 3. In the processes of the superheater, steam temperature and enthalpy value was high in the middle of the flue and low around the side. The uneven distribution of the second process steam temperature and enthalpy value of was larger, and because their temperature and enthalpy value was high, which could easily led to adverse consequences.4. As flue gas temperature, breathing rate flue width along both sides was high among low distribution of the gas and makes the flow direction of the vertical layout of a row of control, and distribution of thermal load as a whole have all the middle, both sides trends in the distribution of low. Flue gas flow direction along the heat load was high to low distribution.5. As a result of the deviation of heat and flow the maximum temperature appeared on the surface of the twelfth tube in the first line which was in the middle of the flue .It became the most dangerous tube. In the three working loads , the full load was the most dangerous one .The numerical simulation can be used on the optimizing design or accidental diagnosis of superheater of marine boiler, at the same time it can economize large numbers of manpower and material resources. Numerical simulation methods would be extensively applied to boiler design and operations safely in the future.