Impact of HRSG characteristics on open volumetric receiver CSP plant performance

The use of near-ambient pressure air as the heat transfer fluid in central receiver concentrating solar power (CSP) plants operating the water/steam cycle presents a number of potential benefits that have attracted research attention to the concept. In such plants, an open volumetric solar receiver (OVR) is used to heat air entrained from the atmosphere and a heat recovery steam generators (HSRG) is employed to transfer heat from the air to the water/steam cycle. An aspect of this technology that has not been previously addressed in the literature is the impact that the selection of HRSG configuration and operating parameters has on overall plant performance, and in particular, which HRSG characteristics allow for the best utilisation of solar energy. The results presented in this paper address these questions by evaluating the impact of HRSG operating characteristics on the performance of a 100 MWe OVR central receiver plant. Investigations are carried out on the basis of coupled OVR/HRSG/water/steam cycle models implemented and solved in the EES© programming environment. Single and multi-pressure HRSG arrangements with and without reheating are examined. In specific terms, sensitivities to the variation of receiver outlet temperature, air return strategy, air return ratio, HRSG pinch-point temperature difference, deaerator outlet temperature and duct velocity are evaluated and discussed.