Effect of apparent gas velocity on performance of oleophobic coalescence filter cartridge and its structure improvement

The frequent fluctuation of gas flow during the storage and transportation can easily lead to the failure of filter cartridge and the shortening of its service life. Thus, an experimental device for the filtration performance of coalescence filter cartridge was established according to the relevant test standards. On this basis, the effects of apparent gas velocity and its dynamic change on the saturation of oleophobic coalescence filter cartridge, the liquid distribution and the state of downstream droplets were analyzed, and a new method of setting baffle inside the filter cartridge was proposed. In addition, the optimal baffle height that could greatly improve the performance of filter cartridge was explored. The results show that the saturation of the first layer, especially the lower part, of the filter cartridge decreases with the increase of apparent gas velocity. The dynamic change of apparent gas velocity has a great influence on the saturation of the first and last layers of filter cartridge. Increasing the apparent gas velocity appropriately within the acceptable range of experiment can accelerate the migration of liquid. However, the adhesion of fiber to droplets is relatively weakened when the apparent gas velocity reaches 0.5 m/s, and thus the droplets are easy to detach from the fiber, leading to the re-entrainment and further reducing the filtration efficiency. The baffle structure inside the filter cartridge can effectively avoid the re-entrainment of droplets at high apparent gas velocity. The filtration performance of the filter cartridge is improved most significantly at the baffle height of 15 cm, and the number concentration of downstream droplets is also decreased by 97.3% compared with the structure without baffle. Conclusively, the research results could provide important guidance to the development of efficient coalescence filter cartridge and the optimization of storage and transportation process of natural gas.