Innovations on Direct Steam Generation in Linear Fresnel collectors Luis Coco Enríquez, Javier Muñoz-Antón, José M. Martínez-Val enriquez.luis.coco@alumnos.upm.es Grupo de Investigaciones Termoenergéticas (GIT), ETSII-UPM GIT Abstract Main solutions proposed in this study are: - Capabilities comparison between System Advisor Model (SAM) and Thermoflow for Linear Fresnel (LF) Direct Steam Generation (DSG) power plant design (qualitative and quantitative study): https://sam.nrel.gov/content/sam-virtual-conference-july-23-2013. Comparing SAM and Thermoflow for Linear Fresnel Plants. - LF Solar Field (SF) configuration with Direct Steam ReHeating. - LF SF configuration [1] with liquid phase recirculation to next loops group: International Patent, Publication Number: WO 2013/045721/ A1. - LF SF Once-Trough (OT) [2] configuration with water injections, similar to DUKE project for parabolic collectors. LF DSG software selection: Thermoflow & SAM (NREL) Thermoflow main capabilities are: - Graphical simulation enviroment showing stream properties. - SF configuration modeling flexibility. - Receiver heat losses accurate model (Kandlikar, Dittus-Boelter ). - Receiver tubes thickness calculation and stress limit. - Balance Of Plant (BOP) ReHeating modeling. SAM (NREL) main capabilities are: - Meteorological data directly loaded from weather files (TMY2, TMY3, EPW). - SF Thermal Interita consumed during start up, shut down and transitories. - SF control parameters (flow limit, stow and deploy limit, freezing limit, etc). - BOP operational modes (start-up, shut-down, stand-by, etc). - SF and BOP parasitic energy looses details. Main quantitative differences are: - Solar collectors end-losses calculation methodology. - Air cooled condenser part-load levels: fan power consumption. - Thermal-inertia energy consumption to heat up receivers and headers. BOP equipments part-load performance parameters. - Financial and economic models. Design-Point (with Direct ReHeating) LF DSG plant with Direct ReHeating Annual Performance (517ºC Direct ReHeating) Conclusion Thermoflow and SAM future developments could share capabilities in order to gain synergies for LF DSG power plants design. Direct ReHeating with LF DSG solar collectors increases unitary power (kW/m2), power cycle efficiency, and annual plant performance. A new SF configuration was proposed grouping ReHeating solar collectors around BOP in order to reduce steam pressure drops. An innovative SF configuration [1], recirculating liquid phase to adjacent loops was proposed. This solution is suitable to avoid desequilibrium between paralell loops. This new configuration also integrates SuperHeating and Direct ReHeating solar collectors grouping around BOP to reduce headers pressure drops and thermal losses. OT [2] LF DSG configuration was also modeled in Thermoflow. OT with water injections, to reduce thermal stresses, is a solution under development in DUKE project for parabolic collectors. OT constitutes a feasible solution to reduce number of equipments (recirculation pumps, phases separation tanks), headers length, between other advantages. - New materials [3], under development for fossil supercritical plants, will permit pressure and temperature levels up to supercritical water SF configurations. Fig. 1.SF configuration with Direct ReHeating LF DSG collectors around BOP to minimize pressure drops. 50 MWe Gross Power (13 + 13) loops with recirculation. Innovative SF configuration with liquid phase recirculation to adjacent loops group [1] Fig. 2. SF configuration [1] with Liquid Phase recirculation to next adjacent group. SuperHeating and ReHeating LF DSG collectors area located around BOP . References: [1] José María Martínez-Val Peñalosa, Manuel Valdés del Fresno, Alberto Abánades Velasco, Rafael Rubén Amengual Matas, Mireia Piera Carreté. Universidad Politécnica de Madrid (UPM), Spain.International Patent, Publication Number: WO 2013/045721/ A1.“Solar Power Plant for Direct Steam Generation”. [2] Jan FabianFeldhoff (1), Martin Eickhoff (2), RamkumarKarthikeyan (3), et al. German Aerospace Center (DLR),CIEMAT, SolarPACES 2012. “Concept comparison and test facility design for the analysis of Direct Steam Generation in Once-Through mode”. [3] EPRI. Electric Power Research Institute. G8 Cleaner Fossil Fuels Workshop. Stu Dalto, Director, Generation, IEA Secretariat, Paris France, 17-18 January, 2008.“Boiler material for USC pulverized coal (PC) Plants”. Acknowledgements: Technical discussions within Thermo-Energetic Research Group (UPM) were essential for this work.