Study on Air-Fly Ash Particles Flow Characteristics in Secondary Air System of Tangentially Fired Pulverized Coal Boiler
The secondary air system is an important part of the combustion system of pulverized coal boiler.The deposition of fly ash particles carried in the air of the secondary air system will affect the air flow characteristics,and even affect the safe operation of the boiler.In this paper,the secondary air system of a 350 MW supercritical tangentially fired pulverized coal boiler is taken as the research object,and the air-fly ash particle flow characteristics are calculated and analyzed by numerical simulation.The calculation results show that under the condition of equal air distribution mode of secondary air baffle opening,the auxiliary air velocities of the middle four layers are basically the same,and the air flow rate of the SOFA of the three layers accounts for 38.4%of the total secondary air.When the opening of each secondary air baffle is unchanged,the change of the secondary air inlet velocity(secondary flow rate)has little influence on the air flow rate distribution of each burner nozzle.Due to gravity,the fly ash particles flow downward after entering the windbox,and the larger the particles are,the more obvious the trend is.The ash content of auxiliary air in layer AA is large,so the water wall near this nozzle outlet is easy to wear.Fly ash particles are easy to deposit at the windbox bottoms of No.2 and 3 corners,so it is necessary to design ash discharge pipe reasonably at the bottom.
tangentially firedsecondary air ductwindboxfly ash particlesdeposit
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