ANALYSIS OF THE OPERATING MODE INFLUENCE ONTO ENERGY CONSUMPTION OF A NATURAL GAS STORAGE PLANT

Natural gas carrying from production sites to users’ facilities is made by marine shipping in liquid phase or by terrestrial pumping in gaseous phase through long pipelines. In the latter case several storage stations are distributed along the pipeline nets to move the natural gas from its deposits to users’ terminals. Storage stations are set up to compensate seasonal fluctuations of the consumer demand versus methane supply, storing the gas in various kinds of reservoirs. In most of such plants centrifugal compressors are used, where the energy and the time that a complete charge takes are affected by the operation scheduling of the compressor from the minimum to the maximum storage levels. While the pressure in the reservoir enforces the instant operation pressure, the flow rate is limited within a quite wide range. Here an in-house code, based on the lumped parameter approach and a quasi-steady dynamics, is applied to a complete charge. The natural gas behavior is modeled by the pseudo-ideal gas in order to get a fair accuracy keeping the usual gas dynamics equations. The compression path has been parameterized and a multi objective optimization, embedding the simulation code, has been implemented to find the most suitable management of the compression station for the minimization of time and energy. The most significant paths are analyzed to pick out the effects of the compression strategy.