(492c) Design and Analysis of the Natural Gas Liquefaction Optimization Process- Energy Storage of Cryogenic Carbon Capture (CCC-ES)

Authors: 
Fazlollahi, F., Brigham Young University
Baxter, L. L., Brigham Young University

The cryogenic carbon capture (CCC) process provides energy- and cost-efficient carbon capture and can be configured to provide an energy storage system using an open loop natural gas (NG) refrigeration system. This system stores energy during non-peak times by liquefying and storing natural gas to be used as a refrigerant. When the energy is at a premium during peak demand, the stored liquefied natural gas carries out the cryogenic separation process relieving the parasitic load on the power plant. The natural gas either returns to the pipeline or combusts in a simple natural gas turbine after the gas has been vaporized and warmed, increasing the power output of the plant during peak demand by reducing the parasitic losses associated with carbon capture.

This investigation compares four different natural gas liquefaction processes simulated by Aspen HYSYS as incorporated as part of the CCC-ES process. In these processes, LNG vaporizes in the CCC process and the cold vapors return through the LNG heat exchangers exchanging sensible heat with the incoming flows. Aside from this difference, this investigation uses process designs similar to traditional LNG processes. The simulations meaningfully compare these alternative liquefaction options, eliminating differences in assumptions and process details inherent in comparing processes simulated by different authors or different codes. The comparisons include costs and energy performance with individually optimized processes, each operating at three operating conditions: energy storage, energy recovery, and balanced operation. The results indicate that turbomachinery efficiency influences overall performance. Given similar quality turbomachinery, efficient heat exchangers in particular reduce energy input requirements and maximize energy savings and capital costs, including heat exchangers used to cool compressed gases.