Numerical Simulation Research Of Cold Flow Field In 260t/h Tangentially Fired Boiler

The experimental research of the tangentially fired boiler needs huge manpower and resource. With the development of the computational fluid mechanics, numerical simulation is applied more and more in the engineering research field, and becomes an important technology of studying the boiler flow field characteristic. The furnace cold flow field under design condition and various working conditions are numerical simulated based on the 260t/h tangentially fired boiler in this paper.As the exist of pseudo-diffusion in the tangentially fired boiler numerical simulation, first the mesh pattern is compared and analyzed, the tetrahedron mesh splitting style is determined, and the non-uniform mesh dividing technology is adopted; then the different turbulent models and differential scheme are compared, finally the attainable k ?εturbulent model which matches the tetrahedron mesh and high precision QUICK format are chosen, this method can reduce the pseudo-diffusion effectively.The furnace cold flow field of the 260t/h tangentially fired boiler is numerically simulated, and the distribution law of the velocity vector, pressure and turbulent kinetic energy of various sections are researched, the characteristic of the air dynamic field is summarized; the numerical simulation result shows that: because the difference of the primary, secondary and tertiary air tangent circle, the variation of the furnace flow field is huge, which causes the air flow brushing the wall and slag on the water cold wall.On the above working basis, the characteristic of furnace cold flow field is researched through altering the secondary air tangent circle, the result shows that: increasing the radius of the secondary air tangent circle will strengthen the flow jet and the air flow fullness in the boiler, also increase the flow distance of the coal grain, which is advantage for the burning out of the coal and increasing the boiler efficiency and preventing the slag of the furnace outlet; but when the secondary air tangent circle is too huge, the jet will cause the cold water wall slag; it is better when the secondary air tangent circle is the same with the tertiary air.At the center of the secondary air, the two angle ramp, two angle tangent arrangement are adopted, the cold flow field characteristic in different tangent diameters and tangent ways are researched, the results show that: when the first and tertiary angle tangent, second and fourth angle ramp, it is best to adopt the size same as the primary air tangent circle diameter; while the first and tertiary angle reverse tangent, second and fourth angle ramp, it is better to adopt the size same as the tertiary air tangent circle diameter.