There have been continuous efforts by researchers and power producing companies to reduce various costs involved in solar power tower (SPT) plants. Economically deploying conventional SPT plants for industries using thermal or thermo-chemical processes which need temperatures >1100 K could be challenging. Here, the overall economics of deployment of conventional SPT could go unfair as such design needs larger heliostat field, therefore costlier stiffer heliostats to reach high concentration ratio (CR). These challenges can be solved by beam-down SPT which uses secondary reflector mounted on tower top and receiver cum secondary concentrator on the ground could achieve desired CR, is one potential candidate to save on tower construction and pumping costs. Using beam-down SPT heat can be made available at the ground which opens an option of extracting the heat using natural circulation loop (NCL). The current paper explores the new proposed configuration of NCL in terms of understanding thermal hydraulics using 3-D CFD simulations. Further, it also incorporates optimization of the proposed design configuration using formulated heat transfer model. The optimized geometry is simulated using 3-D CFD simulation which gave the desired rating. (C) 2018 Elsevier Ltd. All rights reserved.