Demonstration Reactor System for the Indirect Solar-Thermochemical Reduction of Redox Particles—The Particle Mix Reactor

Abstract

In contrast to thermal receivers that provide heat for steam cycles, in solar thermochemistry often receiver-reactors are used, where materials undergo a reaction while being irradiated by concentrated sunlight. When applied to two-step redox cycles, multiple processes take place in such receiver-reactors, though on different timescales. This leads to design compromises and to high technical requirements for the implementation. A concept for an indirect particle-based system for thermochemical cycles was therefore proposed in which the heat required for the reduction of redox particles is provided by inert heat transfer particles that absorb concentrated solar radiation in a dedicated particle receiver. The novel and central component in this indirect system is the particle mix reactor. It functions by mixing the two particle types for heat transfer and establishing a controlled atmosphere under decreased oxygen partial pressures in a common reactor chamber. The design of an experimental setup for demonstration and investigation of the particle mix reactor is presented in this work. Potential operation modes and design options for particle heater, mixing unit, and oxygen partial pressure decrease are discussed and illustrated. The selection of a mixer type is based on the homogeneity of the obtained mixture. It is supported by the use of discrete element method (DEM) simulations, which were compared to experimental results from a separate setup. Heat loss estimations for the mixing process in the selected mixer geometry are performed for alumina heat transfer particles and strontium iron oxide redox particles. The components' geometries, the overall experimental setup design, as well as operation steps are presented.

Oxygen Crossover in Solid-Solid Heat Exchangers for Solar Water and Carbon Dioxide Splitting: A Thermodynamic Analysis

“…Like rotating systems, particle concepts allow continuous operation of the process. Richter et al [25] and Felinks et al [26] studied heat exchange between reactive particles and inert particles used as heat transfer medium. The utilization of heat transfer particles allows separation of oxidized and reduced particles.…”

Oxygen Crossover in Solid–Solid Heat Exchangers for Solar Water and Carbon Dioxide Splitting: A Thermodynamic Analysis

“…Like rotating systems, particle concepts allow continuous operation of the process. Richter et al [25] and Felinks et al [26] studied heat exchange between reactive particles and inert particles used as heat transfer medium. The utilization of heat transfer particles allows separation of oxidized and reduced particles.…”

Isothermal Splitting of CO2 to CO Using Cobalt-Ferrite Redox Looping

“…This potential risk calls for carbon capture and active sequestration, and utilization in parallel with efforts on renewable energy to effectively seek carbon negative pathway for the near future. The demand for carbon based energy, value-added chemicals, the need for renewable energy utilization and the necessity for CO 2 utilization can all be addressed together via solar-thermochemical conversion of CO 2 and H 2 O into syngas (CO and H 2 ) which can then be utilized for various applications including carbon energy and chemicals production [4,5].…”