Exergetic and economic evaluation of safety-related concepts for the regasification of LNG integrated into air separation processes

Natural gas is an important primary energy carrier and plays an important role for the energy supply. The growing liquefied natural gas (LNG) market enables more flexibility in the entire natural gas market. In the regasification terminal, the LNG is regasified, stored and finally distributed to the gas grid. Usually, the low-temperature exergy of the LNG is destroyed while regasified. Alternatively, there are systems where the low temperature of the LNG is used within power systems. A further option is the integration of the regasification of LNG into an air separation process. In this paper, the concepts of integration of LNG regasification into an air separation processes are developed taking into account different possible structures of air separation units (with and without a nitrogen liquefaction block) and safety-related issues. For the evaluation of the novel concepts, exergetic and economic analyses are conducted. The results show that for safety-related concepts the exergetic efficiency is reduced from 53.4% to 51.8%. The results of the economic analysis demonstrate that the systems with a nitrogen liquefaction block are by 10% more expensive, and that the systems where the safety aspect is included are 9% less expensive. (C) 2017 Elsevier Ltd. All rights reserved.