10 MW/sub e/ Solar Thermal Central Receiver Pilot Plant: thermal storage subsystem evaluation. Final report

Abstract

This report presents an evaluation of the Thermal Storage subsystem at Solar One, the 10 MW/sub e/ Solar Central Receiver Pilot Plant near Daggett, California. The Thermal Storage Subsystem has an availability of around 90%, a first law thermal efficiency of 83%, and can achieve its design discharge capability of 7 MW/sub e/ (net) for four hours. The heat transfer oil mass loss due to thermal decomposition at its elevated temperature is between 5 and 7% of the oil inventory per year - a loss within the range predicted by laboratory experiments. The Thermal Storage Unit tank wall stresses appear to have risen slightly; however, inaccuracy of the strain gages makes conclusive statements impossible. Heat exchanger leaks appeared in the flange seals and the tube-to-tubesheet rolled joints of the charging heat exchangers. Repairs were successful on the flange joint seals, but were unsuccessful on the tube-to-tubesheet seals. Overall, the Thermal Storage Subsystem has functioned well and has met design specifications.