A method for modelling variable speed compressor in chemical process simulators

In this present work, a mathematical model for modelling and simulating a variable speed compressor in chemical process simulators has been proposed. If a variable speed compressor characteristic performance maps are modelled by a bivariate cubic spline approximation it seems the results obtained are in very well agreement with a compressor performance maps generated with original theory calculations. When the pressure ratios are calculated for near zero flow condition the correct form of compressor performance is obtained. The cubic spline approximation can be modelled very well in SIMULINK, and this proves to be a tool for more accurate simulations of compressor performance prediction. The complexity of the compressor characteristic function drastically increases with its use, since it holds much more information compared to third order polynomial fitting. This model can be very easily integrated with process engineering simulators when the compressor performance curves are available. As an example this model has been used to simulate the recycle loop of a centrifugal compressor for surge control