Erosion Analysis And Numerical Simulation Of Economizer In Power Plant Boiler

After coal particles burning, fly ash particles which entrained in the flue gas impact on the economizer tubes, then erosion is produced. Erosion will result in strength reduction of the tubes, which finally causes tube explosion. Compared with other heating surfaces, economizer is arranged in the lower tail of the furnace, the temperature of flue gas in economizer zone is lower, the hardness of fly ash particles is higher, the speed is faster because of the gravity, so erosion in the economizer zone is more serious.Erosion of economizer can be caused by many factors, such as the physical properties of the particles (composition, particle size, shape, and hardness), velocity of flue gas, economizer arrangement, and so on.With the help of Fluent software, this paper took the gas-solid flows which contain in flue gas and ash particles into consideration, and decided to select Discrete Phase Model to simulate the process of fly gas and ash particles flowing economizer zone. The turbulence model chose RNG k-ε model.The research focused on the formation of flue gases gallery between elbows and the wall, as well as the impact on flow field because of different arrangements (in-line and staggered bundle of the economizer) in order to determine the erosion rate.We could analyze the formation and characteristics of flue gases gallery. Flue gas flows in the economizer zone, because the pressure decreases between elbows and furnace wall, where the drag coefficients are lower, some fly gas flows toward the gap, then flue gases gallery generates. The velocity of flue gas and fly ash particles increases gradually, until the outlet boundary, the velocity is almost twice. At the same time, the average velocity of flue gas in the gap is higher than straight pipe, which will cause the erosion rate increasing. So we need to take measures to prevent erosion of elbows.Through the analysis of in-line pipe and flow field, we found that the maximum erosion of in-line pipe occurs at the first row. However, it occurs at the middle rows of staggered bundle. The different structures are the main reason, and erosion of staggered bundle is higher.The contents which this paper simulated agree with the actual facts. It is of great benefit to theoretical research, and it can guide the operation.