Oil-Water-Gas Three-Phase Separation in Multitube T-Junction Separators

Abstract

Multitube T-junctions can be used as an oil-water-gas pre-separator in the oil and gas industry. In this paper, the mixture model, coupled with the k-ε turbulent model, was applied for a simulation of the oil-water-gas three-phase flow characteristics in the multitube T-junction separator. The oil droplet size ranged from 1 to 4 mm. The water content ranged from 5% to 20% and the gas content from 3% to 25%. According to the phase separation results for different droplet sizes, it was found that, as the oil droplet size increased, the water content at the water outlet initially increased and then tended to be stable. Therefore, it was necessary to increase the oil droplet size through corresponding measures before flowing into the T-junction for separation. For the separator with an inner diameter of 50 mm, the oil content at the inlet had a great influence on the water-oil separation performance, and the water-oil separation performance was obviously improved as the oil content decreased. Owing to increased residence time, the oil content had little influence on the water-oil separation performance when the separator with an inner diameter of 100 mm was applied. Moreover, for the separator with an inner diameter of 100 mm, the oil content had little influence on the degassing effect, and more than 90% of the gas could be discharged from the gas outlet. The separation performance of the multitube T-junction separator became worse as the inlet gas content increased.