Optimizing Compressor Operations in an LNG Plant

Abstract Global concern about energy, ecology and environment strongly suggests that energy should be utilized efficiently. Although liquefied natural gas (LNG) is an attractive source of clean fossil fuel, it involves energy intensive liquefaction. Moreover, compressors are often operated in suboptimal fashion in the process, which results in higher energy consumption. The APCI propane precooled mixed refrigerant process is most widely used process in base-load LNG plants. To this end, we optimize the compressor operations for the twin refrigeration cycles of the APCI process. The objective here is to minimize the total power cost for the refrigerant compressors. We identify that the propane pressure in the propane precooling cycle plays a role for the power consumption in the compressors and hence use it as a decision variable. Without much loss of generality, this model could be also used for other LNG processes. Finally, we present a case study on an existing LNG plant model.