Computer control of a complex storage facility

More than 800 MMcfd can now be delivered by Northern Illinois Gas Co. from its Troy Grove storage field using a computer console. A control system, having logging, alarming, flow, and mode control capabilities saves many man hours each day. Eventually, Northern Illinois Gas plans call for company-wide gas control. Compressors totaling more than 60,000 hp withdraw natural gas from the aquifer during winter months. Through proper sequencing of station valves, some of these same compressors are used to inject gas into the reservoir during summer months. The stored gas is used to supplement pipeline supplies during winter. Due to growth at Troy Grove in both physical plant layout and use of machinery, it became apparent that control centralization was necessary. It was decided to install a supervisory control system at the storage facility. The system utilizes a Sigma II computer in conjunction with an Automatic Electric Conitel 2100 master and remote station. In addition to sequencing valves associated with inject, standby, with withdrawal, automatic flow control also was programed. The operation of the system and the economics of it are described in detail.