Techno-economic evaluation for the heat integration of vaporisation cold energy in natural gas processing

Abstract

This paper addresses a conceptual study investigating the techno-economic feasibility for the thermal Integration of LNG cold vaporisation energy in power generation applications. In conventional regasification systems, this valuable LNG cold energy is often being wasted to ambient heat sources, representing a thermodynamic inefficient process with a significant thermal impact on the local environment. A combined facility consisting of a non-integrated Combined Cycle Power Plant (CCPP) and an LNG receiving terminal employing traditional Open Rack Vaporisers (ORV) technology, has been modelled, as a base case. Retrofit strategies for the integration of LNG cold energy have been investigated, and their impacts on power production and system efficiency are systematically compared. Retrofit design options considered in this work include the use of a propane Rankine cycle coupled with the direct expansion of natural gas, the integration of a closed-loop water cycle or open-loop water circuit with a steam Rankine cycle, and the facilitation of integrated air cooling for a gas turbine.