CFB-FGD文丘里管阻力损失与结构优化的数值模拟

Numerical Simulation on Resistance Loss and Structure Optimization of CFB-FGD Venturi Tube

采用k-ε双方程湍流模型对循环流化床烟气脱硫(CFB-FGD)的脱硫塔进行了数值模拟,分析了文丘里结构参数对脱硫塔及其文丘里阻力特性的影响,提出了CFB-FGD烟气脱硫塔文丘里管优化设计的基本原则。模拟结果表明,文丘里管是脱硫塔主要的阻力损失段,占脱硫塔总阻力损失的90%以上,文丘里喉部和渐扩管阻力约占文丘里总阻力的90%以上。通过改善文丘里管的渐缩管、喉部管道和渐扩管的结构型式可以显著降低文丘里及脱硫塔的阻力损失;与直面型文丘里管相比,曲面型文丘里可以减少脱硫塔及文丘里阻力损失的40%以上;相同条件下,全曲面型文丘里结构型式脱硫塔的系统阻力相较于双曲面型可降低17.2%,与原始文丘里结构相比下降幅度能达到77.8%,脱硫塔内压力场分布也相对更加均匀。

Resistance characteristics of circulating fluidized bed flue gas desulphurization （CFB-FGD） tower was simulated by using k-eturbulence model. Effects of the structural parameters of Venturi on resistance loss of CFB-FGD tower and its Venturi resistance were analyzed. Basic principles of Venturi tube optimization design were put forward. Numerical simulation results indicated that the resistance loss of desulphurization tower primarily comes from Venturi tube, which accounts for more than 90% of total resistance loss. The resistance loss of throat-tube and expanding-tube also accounts for more than 90% of total resistance loss of Venturi tube. The resistance loss of CFB-FGD tower and Venturi can be decreased significantly through improving the structure of Venturi＇s reducing-tube, throat-tube and expanding-tube. Compared with straight-surface type Venturi tube, curved-surface type Venturi tube can decrease more than 40% resistance loss of CFB-FGD tower and its Venturi. Under the same conditions, resistance loss of desulphurization tower with whole-surface type Venturi tube can be decreased by 17.2% compared with desulphurization tower with hyperboloid type Vemuri, and the decrease amplitude of resistance loss of desulphurization tower with whole-surface type Venturi tube can reach 77.8% while comparing with the original Venturi structure. At that time, the pressure field distribution in the desulphurization tower is more uniform.