The advantages of high temperature central receiver particle heating solar heat supply systems in concentrator solar power (CSP) have been recognized in recent years. The use of particulate as the collection medium provides two critical advantages: (1) Ordinary particulate minerals and products will allow higher collection temperatures approaching 1000°C compared with conventional molten salts, which are limited to around 650°C, and (2) the low cost high temperature particulate material can also be used as the storage medium in a highly cost effective thermal energy storage (TES) system. The high operating temperature allows use of high efficiency power conversion systems such as supercritical steam in a vapor power cycle or supercritical carbon dioxide in a Brayton cycle. Alternatively, a lower cost gas turbine can be used for the power conversion system. High conversion efficiency combined with inexpensive TES will yield a highly cost effective CSP system. The 300 kW-th prototype is being constructed as a solar heat supply system only, deferring the power conversion system for later demonstration in a larger integrated CSP system.
This paper describes the general design and development efforts leading to construction of the 300 kW prototype system located in the Riyadh Techno Valley development near King Saud University in Riyadh, Saudi Arabia, which is the first sizeable solar heat supply system purposely designed, and constructed as a particle heating system.
An important component in a particle heating system is the particle heating receiver (PHR), which should be durable and efficient while remaining cost-effective. A critical enabling technology of the PHR being implemented for this project was invented by researchers on our team. In our version of the PHR, the particulate flows downwards through a porous or mesh structure where the concentrated solar energy is absorbed. The porous structure will reduce the speed of the falling particulate material allowing a large temperature rise on a single pass. The new design will also increase the absorption of solar energy and mitigate convective heat loss and particle loss. Other innovative aspects of this design include low cost thermal energy storage bins and a cost effective particle to working fluid heat exchanger. Certain features of these design elements are subjects of ongoing patent applications. Nevertheless, the overall design and the development process of the prototype system is presented in this paper.