Study of flow characteristics in straight-flow gas-liquid cyclone separator

Abstract

In recent years, the rapid development of the natural gas industry has put forward higher requirements for gas-liquid cyclone separation technology. However, the separation effect of conventional straight-flow gas-liquid cyclone separator on small-size droplets remains unsatisfactory, and the pressure drop is relatively high. In order to improve the comprehensive performance of cyclone, numerical simulation study was carried out to analyze the distribution of the flow field, droplet particles and liquid film, as well as to investigate the influence of various factors on the flow field and separation performance. The results show that the tangential velocity distribution conforms to the Rankine vortex structure, the local vortex predominantly exists in the bottom center of the cylinder and the exhaust pipe. The liquid droplets are mostly distributed in the free vortex region, and as the flow progresses, the number and sizes of particles gradually decrease, most particles in the exhaust pipe have a particle size of less than 2 μm, indicating that the cyclone is effective in separating small-size droplets, and the liquid film is mainly distributed in the lower part of the cylinder, extending upwards along the helix. Increasing the intake can effectively improve the separation efficiency, within the range of intake from 60 m³·h⁻¹ to 100 m³·h⁻¹, the best separation efficiency—reaching up to 97.5 %—is achieved when the height of the cylinder is 350 mm, the number of blades is 10, the angle of the blade outlet is 25°, and the structure of the exhaust pipe is a straight cylinder with a conical shape, while at the same time generating low energy consumption and a relatively large quality factor indicating excellent overall performance of the cyclone. The results of this study can provide a certain reference value for the optimization design of straight-flow gas-liquid cyclone separator.