FNESS starts to perform biphasic flow calculations, enabling the simulation of problems in condensate systems. Many industries have problems with their condensate systems, usually due to the poor dimensioning of their lines, which can cause serious accidents. Normally, accidents are ruptures in the pipeline resulting from erosion or even FAC wear, associated with excess speed of the biphasic flow that occurs in these lines.
To prevent and avoid these problems, FIGENER developed a module in FNESS that simulates condensate systems. FNESS is a software for calculating the flow and pressure distribution in fluid networks in general. It has a graphical interface for data input/output that allows to build flow models in networks representing:
- Lines with all their characteristics of distributed and singular head loss,
- straight stretches,
- curves,
- transitions
- singularities
- Pumps with their characteristic curves,
- Shut-off and control valves,
- heat exchangers, etc
The hydraulic calculation performed by the FNESS is based on the application of the Bernoulli equation in the system nodes, the junction / interchange points, as well as the points that characterize changes in the elevation of the lines. The calculation results can be shown directly on the problem representation diagram, indicating the pressures and temperatures of the nodes, the flows in the interconnection elements and the flow direction.
In 2011, the FNESS began to be modified to allow variations in density and the mixing of flows with different densities to be included in the principle of energy conservation, an essential condition for treating biphasic flow. In addition to this adaptation, head loss models specific to each two-phase flow regime were included, with the models presented by Nicholas Petalas and Khalid Aziz being adopted in A Mechanistic Model for Stabilized Multiphase Flow in Pipes.
As a result, the following regimes can be identified:
- Laminate Flat
- Wavy Laminate
- Elongated Bubble
- Slugs
- Foam (Froth / Chum)
- Anular / Mist
- Scattered Bubble
In addition to the calculation modifications, new graphic resources were included in the FNESS for the evaluation of condensate systems, such as:
- Color scale applied to the network diagram, allowing to visualize:
- The flow regime
- Mean flow velocity and erosional velocity ranges (API)
- Pressure, temperature and vapor fraction ranges.
- Construction of the Biphasic Flow Map
The figures below show some results of the modifications: