Cracked Gas Compressor Control Tutorial

The market conditions over the couple of years has prompted many end-users to review antisurge control design to help lower their energy index. A number of factors affect antisurge control system design and consequently impact the surge control margins. Cracked/charge gas compressors have evolved over the past decades due to changes in process design. At the same time while compressor configurations have not changed significantly the overall compression cycle has gone through changes. Overall antisurge recycle configurations have changed from one recycle loop per section to one recycle loop protecting three sections. Process changes such as reducing the overall number of furnaces also affects antisurge control system design. In addition to this the extent of fouling of a cracked gas/charge gas compressor also impacts surge. Lastly the impact of other control loops such as driver controls and auxiliary controls also must be taken into consideration. This tutorial will cover all factors associated with antisurge control system design.