Scale-up considerations of the UBFB solar receiver

Abstract

Concentrated Solar Power plants (CSP) are a promising technology for electricity generation. Indirect particle receivers can operate at high receiver temperatures and foster the application of advanced power generation cycles. The present work specifically considers the scale-up of the CNRS concept, referred to as Upflow Bubbling Fluidized Bed (UBFB) system. Previous papers have provided detailed information concerning the on-sun testing of a single tube and of a 150 kW pilot module consisting of 16 parallel tubes. SiC, a Geldart A type powder, was used and fluidized at superficial gas velocities of ∼0.03 to 0.25m s-1. To scale-up these vertical UBFBs, some phenomena require additional attention. These phenomena are 5-fold, and related to (i) the pressure balance over the receiver and the achievable solids' flux and air velocity relationship; (ii) the efficiency of the vertical transport; (iii) the possible particle choking; (iv) the gas-solid hydrodynamics gradually transforming from a freely bubbling into a slugging mode in long UBFB tubes; and (v) attrition and erosion. These phenomena will be further discussed.