| W-shaped flame boiler, which adopts long-flame, air zoning and high concentration factor of pulverized coal, is the preferred stype for anthracite coal combustion because of its superiority on combusting coals of different ranks, stable ignition under part load operation and burning out of fly ash.In this thesis, the aerodynamic fields in a 1025t/h W-shaped flame boiler`s furnace , which is designed and produced by DongFang Boiler Works according to the technique introduced from F&W Co. Ltd of USA , were studied on the single-phase cold model, which is built on the Similarity Theory. An IFA300 constant-temperature anemometer system was used to measure the air velocity in the model. The experimental results reveals that there is a W-shaped flame in the furnace under the present work condition, but the pulverized coal flows too short to burn out, and the dregs under the arch is caused by the back-coming eddies near the burner. Increasing the E-secondary air velocity can shorter the length of the pulverized coal goes, though it enforces the mixing intensity between the primary and the second air, which may promote the combustion of the pulverized coal. Increasing the concentration factor of pulverized coal can is good for controlling the building of NOx, but as the momentum of the primary air is decreased, the dimensionless penetrating depth of the primary air is shorten.The aerodynamic field in the furnace was numerically simulated by FLUENT 6.1. The calculating results showed the regularities that dimensionless penetrating depth varies with the variety of the allocation proportion between different kinds of air, and reveals that the circumfluence areas under the arches can be enlarged by increasing the incidence angle of the F air, which makes the pulverized coal stay longer in the furnace and mix better with the air. But when the incidence angle of the F air is bigger than 30°, the pulverized coal goes through the F-secondary air and makes dregs in the cold ash hopper. So 25°is the best.
|
PDF Full Text Request