Novel Particle Flow Control Using a Scoop Mechanism for Concentrating Solar Applications

Solid oxide particles have been proposed as a cost-effective solution for heat transfer and thermal energy storage (TES) media for next-generation concentrating solar power (CSP) plants because of their ability to operate stably at temperatures > 750 °C. Providing reliable particle flows to particle receivers (RECs) and primary heat exchangers (HXs) for power cycles requires careful design of inlet and outlet flow control valves. To date, sliding gate mechanisms have been used to control the flow of particles in many CSP-TES facilities, but these sliding gate valves can cause particle abrasion. This paper presents the design and testing of a novel particle-flow control mechanism involving a rotating scoop that eliminates abrasion associated with sliding gates. The rotating scoop relies on the particle angle of repose to shut off flow in the closed position. Servo-motor control of the scoop rotation enables setting the rate of particle flow, which falls as a curtain into a freeboard zone of a primary fluidized bed HX or indirect particle REC. Tests with the particle scoop for a multi-channel fluidized bed particle-sCO2 HX demonstrate the effectiveness of this approach to maintain a reliable particle inventory in the HX freeboard zone above the core.