生物质灰在高温旋风除尘器内捕集过程数值研究

Numerical study on capture process of biomass ash in cyclone separator under high temperature

生物质气化站旋风除尘器的内部流场为高温强旋湍流流场,研究其中生物质飞灰颗粒在该高温流场中的运动和分布规律十分必要。鉴于高温下测量飞灰颗粒的运动和分布规律较为困难,应用FLUENT软件对高温旋风除尘器内部风流-飞灰耦合运移规律进行数值模拟。研究结果表明:高温旋风除尘器内部的静压、动压和全压分布均呈现良好的轴对称性;飞灰颗粒整体浓度分布呈螺旋状分布,分离空间的浓度较高,而环形空间顶端出现"顶灰环"现象,器壁附近则呈现波浪状;当燃气温度为200℃时,旋风除尘器的分离效率在风速为24 m/s时最高;在生物质气化站的实际生产过程中,应根据进入旋风除尘器燃气的实际温度来调节风机参数,以使燃气的进口速度调到最佳,进而使分离效率达到最优。

The internal flow field in the cyclone separator of biomass gasification station is a strongly turbulent flow field under high temperature,and it is necessary to investigate the migration and distribution laws of biomass fly ash particles in the high temperature flow field.In view of that it is quite difficult to measure the migration and distribution laws of fly ash particles under high temperature,the FLUENT software was used for the numerical simulation on the coupling migration laws of wind flow and fly ash inside the cyclone separator under high temperature.The results showed that all the distribution of static pressure,dynamic pressure and total pressure inside the cyclone separator under high temperature appeared the good axial symmetry.The total concentration distribution of fly ash particles appeared the spiral distribution,the concentration in the separation space was relatively high,while the phenomenon of upper dust ring appeared at the top of annular space,and the concentration appeared the wavy form near the wall of cyclone separator.When the gas temperature was 200℃,the separation efficiency of the cyclone separator reached the maximum value when the wind speed was 24 m/s.In the actual production process of biomass gasification station,the fan parameters should be adjusted according to the actual temperature of gas entering the cyclone separator,so as to adjust the inlet velocity of gas to be the best and make the separation efficiency be the optimal.