Extensive optimisation analyses of the piping of two large underground gas storage ariel compressors

Two large identical 6-cylinder Ariel JGB/6 reciprocating compressors each of 7.5 MW, are used for an underground gas storage system in (UGS) plant located in Epe, Germany. The compressors can be operated at a wide range of operating conditions, e.g. variable suction and discharge pressures, 2-stage mode during gas storage, 1-stage mode during gas withdrawal, capacity control by speed variation and valve lifters. The system should operate efficient, safe and reliable for the complete range of the operating conditions, which can be guaranteed by an extensive optimization analyses during the design stage of the project. For that purpose TNO has carried out different dynamic analyses according the API Standard 618 to be sure that the system can operate efficient, safe and reliable for the long term. In the present paper a summary of the underground gas storage system is given and the different steps in the optimization process of the system have been indicated. Finally, the results of vibration measurements after start-up of the system are presented, conclusions and remarks are given.