Predictive Surge Control and Optimization for a Centrifugal Compressor

This paper details the installation of a retrofit supervisory control system on a large air compressor for the purpose of minimizing energy costs and protecting the compressor from surge. The paper discusses how an accurate prediction of the compressor’s stable operating region can be calculated to develop a compressor performance “map” and how this map can then be used to cut energy consumption by the compressor driver. The compressor is protected from surging by a “predictive” control method. Instead of waiting for the compressor to surge, and then reacting, the system calculates when surge is about to occur and takes action to avoid a surge event before it occurs. The installation of a control system of this type can result in a substantial dollar savings in energy costs, while guaranteeing that a compressor will be protected from any damage from a severe surge event. This system has been installed in our plant and proven in practice. The paper details the installation of this system and its results.