IDAES Platform for Evaluating Thermal Energy Storage for Coal-Fired Indirect sCO2 Power Cycles

Abstract

This paper demonstrates the modelling of a novel power cycle for coal-fired indirect supercritical carbon dioxide (sCO2). and thermal energy storage (TES). TES integrated with coal fired power plant can improve the efficiency, making the power generator responsive to ramp rate. The parallel models were developed in IDAES, an open-source code developed by the Department of Energy (DOE), and Aspen Plus V.10 by Aspen Technology, Inc., which is used in many industries to model and optimize a variety of chemical processes. The benefit of using Aspen Plus for coal combustion is its ability to model solids and multiphase fluids that will be present in the various coal and sCO2 power cycles. The property database and equations of state (EOS) available in the Aspen and IDAES software provide accurate results for the process conditions present in the cycles involved in this project. A baseline model was selected from DOE studies and compared against results from the system modelling. Current results from the model are close to those found using Aspen and those in the baseline model. The system model was also connected to a dual-media thermocline thermal energy storage system (DMTES) that uses a Python script to determine temperatures of molten salt provided by the DMTES. The code uses variables of heat flow, mass flow, and temperature to determine the performance of the sCO2 power block IDAES model. From this, the power block output is determined for steady state and quasi steady state conditions. The DMTES system is modeled for dynamic situations and is shown to have near-constant temperature during charge or discharge, depending on the position of the DMTES system thermal transition zone. The results show how temperature is maintained across a large range of state-of-charge.