Question:

Does the property quality in "Flow and Geometry variables" of the results tab not indicate "dryness level" rather than humidity? The value is often minus or more than 1. If the property is quality, should it not be between 0 and 1?

Answer:

According to the traditional thermodynamic definition, it is correct to assume that Quality should be between 0 and 1, because it is an indication of the quality in the two-phase region. What Flownex does in the case when a fluid is super-heated (e.g. all the water turned into steam), then the Quality is indicated as a value above 1. When the fluid is fully saturated (e.g. only liquid water is present), then Flownex indicates a negative Quality value. Therefore, as implemented in Flownex, the thermodynamic definition of quality has been extended to indicate when the fluid is not in the two-phase region.

A client in the petrochemical industry sought help with regards to a fired heater employed on a plant. The client wished to perform thermal fatigue and stress analysis on the heater, especially during transient operating conditions such as start-up and on-off cyclic operations, where the possibility for large temperature gradients exists.

Key issues:

• Root cause analysis of operational problems.
• Heat loss to atmosphere.
• Combining flow and flow reversal in distribution network.
• Evaluate economic and functional effect of piping modification.

Methodology:

• Steady state model with as built dimensions.
• Investigate operational behaviour.

Solution:

• Understand system behaviour.
• Propose economic solution.
• Reduction of plant trips.

Key issues:

Methodology:

Solution:

Key issues:

Methodology:

Solution:

This case study demonstrates the transient operation of a two-stage Air Cycle Chiller. The chiller consists of a closed cycle in which dry air is circulated via a set of centrifugal compressors and expanded through a turbine to provide cooling at very low temperatures. A typical application is in crust freezing of pre-baked foods.

Evras Finds Optimum Solution - Highveld Steel and Vanadium Corporation is a leading producer of flat products, structural steel and vanadium slag in South Africa. It is a subsidiary of the Evras international group of companies which is based in Luxembourg. Highveld mines the iron ore used at its steel works itself. The steel works produce about a million tons of steel blocks annually, which are then used to manufacture several products, including structural sections, engineering rounds and rails, plates, coiled plates and sheets.

A client in the petrochemical industry sought help with regards to a fired heater employed on a plant. The client wished to perform thermal fatigue and stress analysis on the heater, especially during transient operating conditions such as start-up and on-off cyclic operations, where the possibility for large temperature gradients exists.

GasOil, a company (www.gasoil.sk) that deals with oil and gas processing plants recently acquired Flownex to perform their thermodynamic and hydraulic analyses. They plan to use Flownex in as much of the following applications as possible to ensure their competitive advantage: