EnginSoft - Conference Abstracts

EnginSoft International Conference 2009
CAE Technologies for Industry

Development of a sonic gas/liquid separator by Fluent

Podenzani F. - ENI R&M
Bennardo A. - ENI R&M

Abstract

The paper describes the development of a gas/liquid separator based on the vapor phase condensation, produced by means of the expansion of a sonic flow and by the subsequent separation due to centrifugal effect. Such separator is used in the water and heavy hydrocarbons separation from natural gas. Both phenomena (condensation and separation) take place in a single apparatus, which is also subjected to the constraint to minimize the pressure loss.
The device is composed by three sections:

• A swirler which induces the rotation of the mixture by means of an array of fins set at a prescribed incidence angle with respect to the flow.
  
• The separator where the liquid phases do condense into drops which the centrifugal force (due to the mixture rotation) leads to the outer wall, from where the condensed drops can be removed. This separator is similar to a typical De Laval nozzle followed by a straight and by a convergent duct.
  
• A divergent duct that allows a partial pressure recovery.

The simulations were carried out by separating the swirler from the downstream devices, to minimize the computational time for the entire study. The swirler necessarily has a threedimensional geometry, and the flow can be modeled as incompressible. Instead, the downstream devices are axissymmetric and a compressible flow modeling is required: a real gas model was adopted, and droplets were simulated using a Lagrangian approach.

In the course of the analysis the configuration of the system was defined, paying special attention to the size of the converging/diverging throats, to the junctions between the various sections, and to the swirler geometry, in order to achieve the aims and the design constraints. A first version of a laboratory apparatus was then constructed and tested by TEA Sistemi, confirming the results of simulations.