Numerical Simulation On The Gas-solid Flow In Diffusion Square Cyclone With A Stick

The cyclone separator is one of the most important parts of the circulation fluid bed(CFB) boiler,the separator is used to keep the solid materiel to be separated and reused,and the square cyclone separators are widely used in the CFB boilers because of their special structure,the square structure is easily for them to be combined with the boiler.A kind of rigid stick were fixed into the separator to reduce the pressure drop,the stick is called reducing pressure drop sticks(Repds).The RSM model was used in the numeral simulation of cyclone separators with reducing pressure drop sticks(Repds).Various sticks with different sizes and different positions were researched,including the flow field,pressure drop and the separation efficiency of the separators.Finally,the result of the simulation was verified by the experiment.The results of the numerical simulation showed that if we fixed a stick with a small diameter into the cyclone separator,the pressure drop didn't change so much. With the increase of the stick's diameter,the pressure drop became lower.While,if we keep increasing the stick's diameter,the separation efficiency of the separator will reduce a little(less than 5 percents).If we just fixed a single stick into the cyclone separator,the fixing angle of the stick had a big influence on the stick's effect of pressure drop.The resistance of the separator changed with different fixing angle,and when the fixing angle was about 170°,the resistance of the separator would depress 30 percents.Sticks with different section shapes had different influence on the separator's slow field,and the pressure drop was different too.The result showed that the sticks with square section behaved better than those sticks with a round section,the pressure drop could be depressed about 32 percents.If we fixed more than one stick into the cyclone separators,the pressure drop would be much smaller,but when the number of sticks was more than 4,the pressure drop would not depress so much.Finally,the result of the simulation was verified by experiment.The result showed that the reducing pressure drop sticks(Repds) could depress the pressure drop of the cyclone separators,and the pressure drop calculated by the simulation was close to the experimental result,the percentage error was less than 11%,so the RSM model and the boundary condition chosen were suitable for the numerical simulation. Besides,the comparison between different models showed that the Reynolds Stress model(RSM) is suitable during the simulation of cyclone separators.