新型离心式脱硫塔气液两相流数值模拟

利用FLUENT软件和SIMPLE算法对新型旋流脱硫塔的气液两相流场进行了数值模拟。计算中气相采用了RSM湍流模型,颗粒相采用了Lagrange坐标系下的随机轨道模型。分析结果表明,气相流场具有强旋流特性;喷射液滴的直径、喷淋量和烟气流速影响其在塔内的分布:喷射液滴粒径越大、喷射量越小、烟气流速越大,入口段降温越少;塔体上方截面平均浓度随液滴粒径的增加而降低,随液气比的增加而增加,随烟气流速的增加会先增加至最高值然后降低。喷淋液滴在其他运行参数不变时,平均粒径范围为0.5～1 mm,会对进口烟气起到较好的净化与降温的作用,并使塔体上方喷淋液滴在截面z=4.15 m处浓度分布均匀且覆盖率高;在保证液滴粒径较小时,通过降低烟气流速或增加喷淋量可提高液滴喷淋覆盖率,使得烟气与喷淋充分接触。计算得到的气相流场分布与实测值吻合较好,证明了数学模型的合理性,为进一步优化分离器结构提供了可靠依据。

Numerical simulation of gas-liquid flow state in scrubber of novel centrifugal flue gas desulfurization tower

Computational fluid dynamics (CFD) software FLUENT and SIMPLE algorithm was used to simulate the two-phase flow in a centrifugal flue gas desulphurization spray tower. The RSM turbulence model was adopted to describe the gas phase,while the particle stochastic trajectory model in Lagrange coordinate system was used to describe the liquid phase. The calculation results showed that the flow field was characterized by a strong cyclone. Gas flow diameter, capacity and velocity influenced spraying droplet distribution. The greater the spray droplet size and the smaller the spray volume, the greater the gas flow rate was, the lesser cool entrance was. The average concentration above the section of the tower increased with droplet size decreased, enhanced with vapor-liquid ratio increased, increased to the top firstly and then decreased with gas flow rate increased. When the spray droplets ranged from 0.5 mm to 1 mm, the spray droplets played a better role in purifying and cooling the tower entrance, and could also cover a high concentration at z = 4.15 m.When the droplet was small, reducing the amount of flue gas flow rate and increasing the capacity of spraying liquid droplets could further improve the desulphurization efficiency. The calculated gas flow was corresponding to experimental data, which validated the suitability of using RSM and particle stochastic model to simulate two-phase flow in the scrubber. The results provided references for separator structure optimization.