FLAMANT Gilles

PROMES-CNRS

Gilles.flamant@promes.cnrs.fr

Options for solar receivers-reactors

28 November 2019

ENSIACET Toulouse

Info-Day

Content

• Introduction to thermochemistry

• How to interface concentrated solar energy and reacting medium?

• Indirect heating reactors

• Direct heating reactors

What is Solar Thermochemistry?

• Transformation of solar heat into chemical energy (stored in chemical bounds)

• Solar Fuels are chemical species produced by solar thermochemistry that may be used as fuels in transportation

• Solar thermochemistry is wider domain that solar fuels addressing production of chemical commodities, materials processing, waste treatment …

Solar Thermochemistry

The system that absorbs concentrated solar energy is

generally where the reaction occurs consequently it is

names

Solar Receiver - Reactor

Applications:

Production of hydrogen and Syngas (H2 + CO)

Mineral thermal treatment (calcination, for example)

Metal recycling

Options for interfacing the

concentrated solar energy and

the reactor

Solar concentrating system

Indirect heating reactor Direct heating reactor

Transfer of solar heat to the chemical reactor using a heat

transfer fluid (HTF).

At high temperature: molten salt (T < 600°C), molten metals,

air and other gases.

Main advantage: allow to use classical solution for the

chemical reactor.

Main drawback: heat losses in heat exchangers

Decoupling solar

absortion and

chemical reaction

Coupling solar

absortion and

chemical reaction

Receiver-reactor technology configuration, no HTF

Main advantage: allow to operate at high temperatures

Main drawback: process control is complex

How to heat the

reactants with

solar energy?

Main advantage: allow to

separate the chemical reaction

and the radiation (better T

control)

Main drawbacks: limitation of

heat transfer flux and wall

temperature

Direct irradiation of the

reactants

Main advantage: allow to

operate at high solar flux and

temperature

Main drawbacks: window is

necessary, limitation in size and

temperature

Indirect heating /

opaque walls

Direct heating / No

walls but generally

windows

Particle and solid-gas reactorsIndirect heating options

Flow

reactors

5-10 kW tube-reactor for biomass

gasification, Univ of Colorado –

NREL

Up to 1400K

5-10 kW fluid wall aerosol flow

reactor for methane cracking,

NREL and Univ. of Colorado.

Graphite wall, up to 2000K

• SiC tubes

10 kW rotating tube-reactor for calcite

decomposition, PSI (Switzerland)

Up to 1400K

Flow and rotary

reactors

Indirectly heated vortex flow

reactor tested to gasify charcoal

PSI (Switzerland)

Fluidized bed

SOLPART PROMES-CNRS Reactor

Air + CO2

outletParticle

inlet

CaMg(CO3

)2

Fluidization air

inlet

(distributor)

Particle outlet

MgO + CaCO3

CaMg CO3 2 → CaCO3 +MgO + CO2

Particle and solid-gas reactorsdirect heating options

Four main categories:

• Fluidized bed

• Rotary kiln

• Entrained-particles

• Porous media.

Fluidized beds

First 1 kW fluidized bed at CNRS (1977)

Decarbonation of calcite, 1200K

Lab FB with draft tube. Niigata University,

Japan, for coke gasification and then to

split water cycles using ferrites.

Fluidized beds

PROMES-CNRS, 2018

Spouted bed

Rotary kilns

The 400 kW rotary kiln particulate receiver combined with cold

and hot storages and a 100 kW multi-stage fluidized bed heat

exchanger developed at CNRS in the mid-eighties. Sand up to

1200K.

Rotary kilns

quartz window

cavity-receiver

water/gas

inlets/outlets

Zn + ½ O2

ZnO

Concentrated

Solar

Radiation

ZnO feeder

quartz window

cavity-receiver

water/gas

inlets/outlets

Zn + ½ O2

ZnO

Concentrated

Solar

Radiation

ZnO feeder

Improved 10 kW rotary solar reactor for

ZnO reduction developed at ETH/PSI 1 kW reduced pressure rotary kiln

developed at PROMES-CNRS.

Rotary kilns

And SOLPART DLR Reactor

Entrained flow

Vortex flow solar reactor developed at

ETH/PSI for carbonaceous matter

gasification

Porous reactor

Cerium oxide-based cycle for CO2 and H2O splitting

ETH Zurich

Acknowledgements

This project has received funding from the

European Union’s Horizon 2020 research and

innovation programme under grant agreement No

654663, SOLPART project

Thank you for your attention