Steam Turbine Optimization for Solar Thermal Power Plant Operation PROCESS3 Steam Turbine Optimization for Solar Thermal Power Plant Operation Andrew Martin, Project Leader James Spelling, Research Student

Solar Electric Technologies are Hot! Huge upswing in PV investments Still €€€/kWh Perhaps most suitable for distributed generation Concentrating Solar Power (CSP) being explored and deployed extensively Spain, USA, Australia major players Feed-in tariffs, Renewable Portfolio Standards major sources for subsidies

Types of Concentrating Solar Power (CSP) Systems US DOE US DOE Power Tower Parabolic Dish US DOE Ausra Parabolic Trough Linear Fresnel

CSP Plant Layout

Operational Challenges – Transient Behavior Start up Shut down

M. Jöcker, SIT

Project Objectives Examine state-of-art CSP technology with focus on steam turbine optimization Suggest practical ways of improving the performance and useful lifetime of the cycle components, notably: Maintaining turbine temperature during stand-by Integrating the performance of the steam turbine with the thermal energy storage unit Optimization of start-up procedures

Methodology Development of dynamic component model of steam turbine Simple 1D (axial) heat transfer model Detailed 2D (axisymmetric) heat transfer model coupled with a Stodola steam expansion model Development of system models Complete system simulation model for gas turbine-based CSP is available Simulation and optimisation of the solar trough plant ST operational strategies via thermal energy storage Comparison of component and system simulation results with experimental data from existing CSP plants

Workpackages and schedule WP1 Literature review  (Anneli Carlqvist) WP2 ST heat transfer models WP2.1 1-D  WP2.2 2-D  (just recently) WP3 Component integration to system model WP3.1 Thermal energy storage WP3.2 Trough collectors and preliminary system simulations WP3.3 System simulations and optimization WP4 Licentiate thesis Ca 6 month delay in completing WP2-WP4

1D Steam Turbine Model A initial 1D (radial) finite-difference model has been developed Three zones considered, namely rotor, stator and insulation Model to be correlated against the results of the more detailed 2D steam turbine model

Detailed Steam Turbine Model A 2D finite volume model, developed in MATLAB to increase flexibility and allow integration with system model Stodola models used to calculate off-design behavior of the steam expansion

Stodola models Links the pressure ratio to the mass flow and temperature of the steam, and allows prediction of the off-design behavior of the turbine

Results to date: Temp vs. time

Results to date: 2-D profiles

Results to date: Animation

Main Components in Trough Plant System Model Plant Component Techniques Feedwater Pump* Mass/Energy Balance Operating Characteristic Storage Tank* Mass/Energy Balances Steam Generator* Pinch Analysis Techniques ε-NTU Techniques Condenser* Fan Drive Power Consumption Parabolic Trough Field (under development) Molten Salt Thermodynamics complete *Spelling et al., ’Thermo-Economic Optimisation of Solar Tower Thermal Power Plants,’ ECOS 2010 (under review)

Ongoing Work Obtain field data from the solar trough plant to use in validating the steam turbine model (WP2) Development of the solar trough field model, based on heat and mass balance equations and trough incidence angle models (WP3) Schedule (2010): April 2-D ST turbine model ready (WP2) July Integrated system model ready (WP3) December Licentiate Report (WP4); completion of project

End of presentation