LNG Receiving Terminal Associated With Gas Cycle Power Plants

Abstract

LNG regasification process needs a considerable quantity of thermal energy that is usually obtained by cooling sea water or by burning a fraction of the evaporated natural gas. These systems, though offering low cost and high reliability, are thermodynamically inefficient: they require energy for water pumping or fuel to provide heat and do not exploit the physical exergy related to the initial conditions of LNG to produce mechanical work. The present paper aims to assess the performances of various gas turbine based cycles which use the LNG regasification process as a low temperature heat sink for power cycles. In particular it will focus on the following configurations: • Closed loop gas cycles • Gas-gas combined cycles • Combined gas-organic Rankine cycles Two different sendout pressure (70 and 30 bar, corresponding respectively to the supply of long-distance pipelines or power plants based on heavy-duty gas turbines) are considered. Their performances are calculated and proper effectiveness indexes (e.g. thermal and exergetic efficiency) are introduced to carry out a comprehensive comparison among the systems considered. A simple economical analysis completes the discussion.