(46a) Analytical Forecast of Compressor Dynamics By Means of Scale Invariant Design Parameters

Since the past decade the global demand for ethylene has increased by approximately 30% and forecasts are predicting a continuously strong positive trend for the future. Today, the growth is driven mainly by the consumption of petrochemical and oil&gas products through the emerging markets, like those of the BRICS countries. Consequently, the construction of a considerable amount of new petrochemical and oil&gas plants is planned. In order to meet the demand, the design of petrochemical plants and oil&gas must become as efficient as possible using work methodologies like concurrent engineering or emphasising additional evaluation techniques like dynamic simulation. Latter can support engineering and process studies and help verify different control system designs. The use of these CAE tools can help detect critical operating conditions at an early design stage, where changes can still be made at low costs. 

Consequently, a dynamic simulation covering all critical transient scenarios is conducted for most of the compressor systems installed in petrochemical and oil&gas plants. These software evaluations are often offered by compressor vendors. However, past experience has shown that due to lack of knowledge about the process conditions, they are often not able to integrate the correct boundary conditions into their model, thus yielding erroneous results. This is why some engineering companies have reverted to conducting the dynamic simulations themselves rather than having them done by vendors or consultants. 

In  the past years the verification of anti-surge valve sizing and compressor control as well as the definition of stable shutdown and start-up sequences has been performed by engineering company of the author itself by means of an in-house dynamic simulation tool with quite satisfying results. In the course of these studies, a best practice method has been found, which entails the following steps:

Analytical Prepreation, Model Setup, Model verification, Dynamic Simulation

The conclusion will state the relevance of these findings and show their significance regarding the future design of compression systems.