空气预热器硫酸氢铵积灰的数值研究

Numerical Simulation of Ash Deposition with Adhesion of NH_4HSO_4 in an Air Preheater

建立了适用于液态黏性NH_4HSO_4沉积的积灰模型,对某SCR脱硝改造后的300MW机组回转式空气预热器蓄热板的积灰过程进行了数值模拟,分析了烟灰颗粒法向碰撞速度和角度、积灰强度、积灰厚度及积灰概率等积灰特性的变化规律.结果表明:在NH_4HSO_4沉积区,上、下板平均积灰强度分别为普通积灰区的7.3倍和4.5倍,且不同颗粒粒径的积灰概率保持在90%左右,而在普通积灰区均小于35%;上板平均积灰强度约为下板平均积灰强度的2倍;积灰厚度与积灰强度的分布规律一致.

A model was built for ash deposition with adhesion of viscous liquid NH4 HSO4, based on which numerical simulations were conducted to study the ash deposition process on the regenerative unit of a rota- ry air preheater in a 300 MW set after retrofit of its SCR denitrification system, so as to analyze the varia- tion law of the ash deposition characteristics, such as the normal impact velocity and angle of particles, and the deposition intensity, thickness and probability, etc. Results show that the average deposition intensity in the area with NH4 HSO4 adhesion is 7.3 and 4.5 times of that without NH4 HSO4 respectively for the upper and lower wall; the deposition probability in the area with adhesion of NH4HSO4 is around 90%, whereas the value in areas without NH4 HSO4 is lower than 35%. The average deposition intensity on the upper wall is 2 times of that on the lower wall. The distribution of deposition thickness is in the same pat- tern as that of deposition intensity.