Design of Coil-Wound Once-Through Steam Generator System for Concentrating Solar Power Plants

The viability of solar tower plants is endangered owing to multiple failures, mainly in their steam generators. These failures produce unscheduled shutdowns with significant economic losses that increase the financing costs of this technology due to its technological risk. On the other hand, if the flexibility of the steam generator rises, solar power tower plants could participate in the energy adjustment market, improving their returns, encouraging the penetration of variable renewable energies, and providing security to the power grid. A novel steam generator system design based on a once-through steam generator composed of two coil-wound heat exchangers is proposed for a highly reliable, flexible, and quick response steam generator. Coil-wound heat exchangers reduce thermal stress and allow part load operation, while once-through steam generators permit fast load changes and reduce the number of components. Compared with traditional shell and tube designs, the results indicate that the proposed steam generator reduces heat exchange area by 22%, molten salt pressure drop by 79%, and tube-to-tubesheet joints by 73%.