Numerical Modeling Of Particle Deposition Of Fly Ash Reburning

Industrial boilers are a kind of important thermal power equipment in China with widely used. Travelling grate boilers hold a large proportion in coal-fired industrial boilers, and play a never ignored role in industrial production and people’s life. But travelling grate boilers also exist many disadvantages. The coal particles can’t be fully burning in the furnace and expel from furnace with exhaust gas, because of the combustion mode of travelling grate boiler. leading to a high carbon content in fly ash and the content of combustible can be as high as40%. The phenomenon caused lower thermal efficiency of boiler, fuel waste and environmental pollution. Face a series of problems that result from high carbon content in fly ash, travelling grate boilers transform by fly ash reburning has been proposed.Thermal efficiency of boiler is improved after transform in the practical engineering application, this technology be proved feasibility. But fly ash reburning will affect the process of combustion in the furnace. The number of particles increase on account of fly ash reburning in the furnace, the particles are small and light, and also have strong adhesion. It easy to cause slagging on the wall of boiler. It is difficult to solve the problem of slagging. Therefore, Numerical simulation of particle deposition on the wall of furnace of fly ash reburning in this paper.This paper use FLUENT software for numerical simulation. Furnace combustion mode contain mathematical model of gas phase, particle phase, particle deposition and radiation model. Simulate furnace combustion status, different coal and the way of air distribution impact on the combustion conditions after fly ash reburning. Comparison and analysis of simulation results and put forward the effective measure to relieve slagging.After fly ash reburning. The thermal zone has been forward to former wall, crown and face arch wall by extrusion in the furnace. The temperature of crown wall, former wall and the back of face arch has been increased, the temperature of backwall has been lower. It’s result in that particle deposition rate has been raised in higher temperature area, the particle deposition rate is very small. The flow field produce disturbance due to fly ash jet in the furnace. airflow velocity has been increased nearby former wall, crown wall and the back of face arch. The number of particle carried by airflow increase with airflow velocity increase. the probability of particle collision and adhesion on the wall increase. The particle deposition rate on the crown wall, former wall and the back of face arch affect larger by combust different coal quality, affect smaller on backwall, rear arch and the front of face arch. The particle deposition rate is larger by burning coal that contain more alkaline oxide,when the mold of air distribution is different. The particle deposition rate on the crown wall, former wall and the back of face arch affect larger, affect smaller on backwall, rear arch and the front of face arch. The particle deposition rate is smallest in the mold of air distribution with Air volume of9%in the first wind warehouse. The particle deposition rate is largest in the mold of air distribution with Air volume of5%in the first wind warehouse, Especially, The influence of the former wall is most obvious. Therefore, the air volume of the first wind warehouse properly increase can reduce deposition and slagging on the wall.