关键词: 多相流, 气液交叉流, 分级效率, 粒子, 数值模拟

Abstract:

A lab-scale Gas-Liquid Cross-Flow Array system (GLCA) was built up to investigate the effect of velocity, arrangement of liquid columns and particle size on separation efficiency of particles in gas by a continuous and regular liquid column array of water. These continuously falling water liquid columns were perpendicular streams to the dusty gas flow, so that particles could be captured by the water streams due to inertial, diffusion and interception mechanism. The experimental results showed that the separation efficiency decreased with increase of the specific surface area and particle size whereas the effect of velocity in the experimental range was unremarkable. Under the optimal column arrangement, a separation efficiency of 37.3%, 43.9% and 99% was achieved for particle size of 0.1, 1 and 10 μm, respectively, at an air velocity of 1 1 m·s^-1 after 162 unit rows. A prediction formula was proposed for extrapolative calculation of grade efficiency of separation and expected pressure drop of a given particle size as a function of the unit number of liquid column arrays. As an example, total pressure drop was expected no more than 300 Pa for 0.4 μm particles at 95% separation efficiency. Large eddy simulation (LES) at the optimized experimental conditions yielded the numeric simulation in good agreement with the experimental data and thus verified prediction formula of separation efficiency. With this model, it is possible to predict the performance of GLCA although other driving forces would be taken into account, e.g. the thermophoretic force and the convection caused by vapor condensation and chemical reactions.

Key words: multiphase flow, gas liquid cross-flow array, grade efficiency, particle, numerical simulation