Numerical analysis of flare gas recovery ejector

Flaring and venting contributes significantly to greenhouse gas emissions and environmental pollution in the upstream oil and gas industry. Present work focuses on a horizontal flow, multiphase ejector used for recovery of these flared gases. The ejector typically handles these gases being entrained by high pressure well head fluid and a comprehensive understanding is necessary to design and operate such recovery system. A CFD based analysis of the flow through the ejector has been reported in this paper. The flow domain was meshed and the mass and momentum equations for fluid flow were solved using commercial software CFX (v14.5). Euler-Euler multiphase approach was used to model different phases. The entrainment behavior of the ejector was investigated and compared for different fluid flow conditions. It was observed that for a fixed primary fluid flow rate, the entrained or secondary flow rate decreased linearly with an increase in pressure difference between exit and suction pressure. The higher was primary flow rate, the greater was the suction created ahead of the primary nozzle and greater was the amount of energy added to the entrained fluid.