Session: 08-01: Solar Chemistry: Thermochemical Fuel Production I

Paper Number: 132482

132482 - Development of a Particle-Based Reactor System for Syngas Production From Concentrated Solar Energy 

Abstract: 

In solar thermochemical redox cycles for syngas production, a metal oxide is first reduced at high temperatures of about 1400°C and low oxygen partial pressures. Then it is oxidized by steam and CO2 at lower temperatures of about 900°C. In state-of-the-art reactors, the metal oxide is a stationary foam structure, so that both reactions take place in the same location. The gas atmosphere is switched accordingly and the temperature is varied by adapting the concentrated solar irradiation, which results in a batch process.

An alternative to periodically changing the conditions in one location is moving the redox material through a reactor system, for example in the form of particles. In this way, the conditions in the respective components and the solar irradiation can be kept constant, which allows a more tailored reactor design for the specific reaction, less complicated heliostat field control, easy replacement of redox material and more options for heat recovery between the high- and low-temperature step, leading to a high projected system efficiency.

Here, the development of such a particle-based reactor system at DLR is being presented. After briefly reporting about recent experiences with a vacuum particle reactor experiment and its challenges, a new particle-based concept is being introduced. In the system, the particles are heated in a solar receiver, descend to a reduction reactor with a countercurrent flow of purge gas, continue to move to the oxidation reactor and are finally lifted back up, where they are pre-heated by hot purge gas from the reduction reactor before they enter the solar receiver again. Moving packed beds are used for atmosphere separation between the components instead of valves. A system model was used to deduce key figures and desirable parameter ranges for the components. Ceria particles have been produced and characterized for the test stand.

For a detailed analysis, the particle flow and heat transfer were simulated by the Discrete Element Method (DEM) and by custom heat transfer models. DEM force model parameters were calibrated for different material combinations. The effect of geometric parameter variations on particle mass flow and flow velocities are being presented. The influence of the motion profile of a particle conveyor on the particle mass flow is being explained and discussed. Comparisons to cold particle flow experiments with 3D-printed prototype geometries are shown for specific components.

Finally, an outlook to future hot experiments is given, where a demonstration system should be erected in DLR’s solar simulator.

Presenting Author: Johannes Grobbel German Aerospace Center (DLR)

Presenting Author Biography: Johannes Grobbel studied Mechanical Engineering with specialization in renewable energy engineering at RWTH Aachen, Germany and at UC Davis, California. After his Master thesis about convective receiver losses of solar tower power plants at DLR in Jülich in 2014, he developed and validated numerical models for the simulation of solar particle receivers in his PhD thesis at DLR, which he defended in 2019. Now as a team leader at the DLR Institute of Future Fuels in Jülich, he investigates solar driven thermochemical redox cycles for hydrogen and synthetic fuel production, in particular processes where particles are involved.

Authors:

Johannes Grobbel German Aerospace Center (DLR)
Ante Giljanovic German Aerospace Center (DLR)
Anika Weber German Aerospace Center (DLR)
Gilbert Haw German Aerospace Center (DLR)
Martina Neises-Von Puttkamer German Aerospace Center (DLR)
Christian Sattler German Aerospace Center (DLR)