Design and Integration of High Temperature Latent Heat Thermal Energy Storage for High Power Levels

Abstract

A latent heat thermal energy storage unit is being integrated into a heat- and power cogeneration plant in Saarland, Germany. This storage unit system will act as an intermediate backup to a heat recovery steam generator and gas turbine and is therefore situated in parallel to this unit, also between the feedwater pumps and the steam main. The steam required is superheated, with a nominal thermal power of 6 MW. The storage unit needs to provide steam for at least 15 minutes, resulting in a minimum capacity of 1.5 MWh. Integration of this storage unit will increase efficiency and decrease fossil fuel use by reducing the use of a conventional backup boiler, while maintaining the steam supply to the customer. The detailed design and a partial build of the storage unit has to-date been successfully concluded, as well as system design and build. Hot and cold commissioning of the storage unit, including filling of the storage unit, will commence following the completion of the storage unit. With the integration of this storage unit, fossil fuel use will be reduced in this power plant. Additionally, the production of superheated steam at a high power level in a latent heat storage unit and a comparison with simulation tools will be possible. This project includes the design, build, commissioning and testing of the storage unit. The paper discusses the detailed design of the storage and system, including the simulations of the system integration.