Influence On Running Efficiency Of Rotating Pulverized-Coal Classifier Based On Different Bending And Twisting Blade

Rotating pulverized-coal classifier is widely used in thermal power plants, it’sone of key equipments in pulverizing system. Its role is to isolate larger ofpulverized coal particles, returning them to the coal mill, and separate qualifiedpulverized coal to the furnace combustion. Main property index of the rotatingpulverized-coal classifier are important data to measure the running efficiency of theclassifier, which directly affects the boiler combustion system, it’s also has a closecorrelation with steadly, efficient and safety operation of the entire unit.Recently, some scholars have made some optimization and renovation to thepulverized coal classifier rotor blade in the MPS medium-speed coal mill. In thispaper, two new type of rotating pulverized-coal classifiers with bowed-twistedblade(type of straight edge bending and twisting and type of curved edge bendingand twisting) were designed. This kind of design can lower the friction loss whenthe air flows in and decrease the eddy current loss when the air flows out, thus, thepower consumption used in coal pulverizing system will be reduced. It also canproduce stronger blasting action in the process, magnify the collision probabilitybetween pulverized coal particles and rotating blades, enhance the workingproperties of the classifier.Using FLUENT numerical simulation software calculate and analysis therunning efficiency when the two designs used on the classifier, find out the beststructure parameters of the bowed-twisted blades (including twisting angle,installation angle, bending angle). Analysis the actual coal flow field in differentconditions, find out the regulation in performance indicators including pulverizedcoal fineness, integrated separation efficiency, ventilation resistance. Throughcomparative analysis, the best structure parameters of the two designs are the same:twisting angle is25°, installation angle is10°, bending angle is15°. In theseparameters, relative to straight edge bending and twisting, the pulverized coalfineness of curved edge bending and twisting classifier reduced1.9%, thecomprehensive separation efficiency increased0.2%, the internal ventilationresistance dropped179Pa. The improvement of the performance indicators is atheoretical reference for the classifier transformation, also has a certain guidingsignificance.