Utilization of the cryogenic exergy of liquid natural gas (LNG) for the production of electricity

Liquid natural gas (LNG) delivered by means of sea-ships is compressed and then evaporated before its introduction to the system of pipelines. The possibilities of the utilization of cryogenic exergy of LNG for electricity production without any additional combustion of any its portion, have been analyzed. Three variants of the plant have been investigated. A cascade system with two working fluids has been analyzed in two first of them. The economic optimization proved that the optimum temperature difference in the LNG evaporation is higher than initially assumed. Therefore, a third variant of the plant has been analyzed, with ethane as a single working fluid. Only the third variant has been analyzed in detail. The economic optimization of the minimum heat transfer temperature difference (pinch value) in particular heat exchangers has been performed and then the optimum heat transfer area of heat exchangers has been calculated. The influence of the changing ambient temperature on the efficiency of the cold power plant has been analyzed. The own cost of the produced electricity, the annual profit and the pay-back of the plant have been evaluated. The attained reduction of CO2 emission in national economy has been calculated. The analysis of the sensitivity of economical profit on the deviation of economic data has been determined. (C) 2009 Elsevier Ltd. All rights reserved.