Experimental investigation of gas-liquid two-phase flow separation behaviors in a U-type separator

Conventional gas-liquid separators frequently fail to operate effectively under conditions of high gas velocities. This paper introduces a novel U-type gas-liquid separation device, comprising two sub-separators linked by a U-shaped tube. Each sub-separator is equipped with a swirl vane positioned upstream, and features three tangential narrow conduits for separation, arranged along the pipe wall. The experiments are conducted in a gas-liquid two-phase flow loop with the inner diameter of 35 mm. The working fluid is air and water, with the liquid superficial velocity (U-SL) ranging from 0.0 to 0.17 m/s, while the gas superficial velocity (U-SG) varied from 0 to 30 m/s. The observed flow patterns included wavy flow, annular flow, and slug flow. The experimental results demonstrate that complete gas-liquid separation is achieved when the liquid superficial velocity is maintained below 20 m/s. When the gas velocity exceeds 20 m/s, the two-phase flow transitions to an annular flow regime. The annular flow decreases the separation efficiency, but it can still be above 70 %. Higher separation efficiency is attained with conduits width of 3 mm(U-SG<20 m/s) and conduits width of 6 mm(U-SG >= 20 m/s), positioned 1.5D downstream of the separator vanes and the two-stage separator is equipped with a vane. Relative to both the single-stage separator and the GLCC, the U-type separator demonstrates enhanced overall separation efficiency.