Experimental Investigation of the Solar Carbothermic Reduction of ZnO Using a Two-cavity Solar Reactor

2004 ◽  
Vol 126 (1) ◽  
pp. 633-637 ◽  
Author(s):  
T. Osinga ◽  
U. Frommherz ◽  
A. Steinfeld ◽  
C. Wieckert
Keyword(s):  
Carbothermic Reduction ◽  
Chemical Conversion ◽  
Chemical Reactor ◽  
Reaction Chamber ◽  
Solar Furnace ◽  
Molar Ratio ◽  
Solar Simulator ◽  
Co2 Emission Reduction ◽  
In Series ◽  
Reduction Of Zno

Zinc production by solar carbothermic reduction of ZnO offers a CO2 emission reduction by a factor of 5 vis-a`-vis the conventional fossil-fuel-based electrolytic or Imperial Smelting processes. Zinc can serve as a fuel in Zn-air fuel cells or can be further reacted with H2O to form high-purity H2. In either case, the product ZnO is solar-recycled to Zn. We report on experimental results obtained with a 5 kW solar chemical reactor prototype that features two cavities in series, with the inner one functioning as the solar absorber and the outer one as the reaction chamber. The inner cavity is made of graphite and contains a windowed aperture to let in concentrated solar radiation. The outer cavity is well insulated and contains the ZnO-C mixture that is subjected to irradiation from the inner graphite cavity. With this arrangement, the inner cavity protects the window against particles and condensable gases and further serves as a thermal shock absorber. Tests were conducted at PSI’s Solar Furnace and ETH’s High-Flux Solar Simulator to investigate the effect of process temperature (range 1350-1600 K), reducing agent type (beech charcoal, activated charcoal, petcoke), and C:ZnO stoichiometric molar ratio (range 0.7–0.9) on the reactor’s performance and chemical conversion. In a typical 40-min solar experiment at 1500 K, 500 g of a ZnO-C mixture were processed into Zn(g), CO, and CO2. Thermal efficiencies of up to 20% were achieved.

Experimental Investigation of the Solar Carbothermic Reduction of ZnO Using a Two-Cavity Solar Reactor

Solar Energy ◽  
2003 ◽  
Author(s):  
T. Osinga ◽  
U. Frommherz ◽  
A. Steinfeld ◽  
C. Wieckert
Keyword(s):  
Carbothermic Reduction ◽  
Chemical Conversion ◽  
Chemical Reactor ◽  
Reaction Chamber ◽  
Solar Furnace ◽  
Molar Ratio ◽  
Solar Simulator ◽  
Co2 Emission Reduction ◽  
In Series ◽  
Reduction Of Zno

Zinc production by solar carbothermic reduction of ZnO offers a CO2 emission reduction by a factor of 5 vis-a´-vis the conventional fossil-fuel-based electrolytic or Imperial Smelting processes. Zinc can serve as a fuel in Zn-air fuel cells or can be further reacted with H2O to form high-purity H2. In either case, the product ZnO is solar-recycled to Zn. We report on experimental results obtained with a 5 kW solar chemical reactor prototype that features two cavities in series, with the inner one functioning as the solar absorber and the outer one as the reaction chamber. The inner cavity is made of graphite and contains a windowed aperture to let in concentrated solar radiation. The outer cavity is well insulated and contains the ZnO-C mixture that is subjected to irradiation from the inner graphite cavity. With this arrangement, the inner cavity protects the window against particles and condensable gases and further serves as a thermal shock absorber. Tests were conducted at PSI’s Solar Furnace and ETH’s High-Flux Solar Simulator to investigate the effect of process temperature (range 1350–1600 K), reducing agent type (beech charcoal, activated charcoal, petcoke), and C:ZnO stoichiometric molar ratio (range 0.7–0.9) on the reactor’s performance and chemical conversion. In a typical 40-min solar experiment at 1500 K, 500 g of a ZnO-C mixture were processed into Zn(g), CO, and CO2. Thermal efficiencies of up to 20% were achieved.

Hydrogen Production by Steam-Gasification of Petroleum Coke Using Concentrated Solar Power: Reactor Experimentation With Slurry Feeding

Solar Energy ◽  
2006 ◽  
Author(s):  
Andreas Z’Graggen ◽  
Philipp Haueter ◽  
Gilles Maag ◽  
Alfonso Vidal ◽  
Manuel Romero ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Conversion Efficiency ◽  
Chemical Conversion ◽  
Chemical Reactor ◽  
Energy Conversion Efficiency ◽  
Steam Gasification ◽  
Solar Furnace ◽  
Molar Ratio ◽  
Particle Size Range ◽  
Reactor Temperature

We report on the experimental evaluation of a 5 kW solar chemical reactor for the steam-gasification of petcoke, carried out at PSI’s solar furnace. A petcoke-water slurry was continuously injected into a solar cavity-receiver to create a vortex flow directly exposed to concentrated solar radiation. For a nominal reactor temperature of 1500 K, a residence time of 2.4 s, and a water-petcoke molar ratio of 4.8, the maximum degree of petcoke conversion was 87%. Typical syngas composition produced was 62% H2, 25% CO, 12% CO2, and 1% CH4. The energy conversion efficiency — defined as the portion of solar energy absorbed as chemical energy and sensible heat — attained 17%. The effect of varying the particle size (range 8.5–200 μm) and slurry stoichiometry (range 2.1–6.3) on the degree of chemical conversion and energy conversion efficiency was examined.

A 300 kW Solar Chemical Pilot Plant for the Carbothermic Production of Zinc

Solar Energy ◽  
2006 ◽  
Author(s):  
C. Wieckert ◽  
E. Guillot ◽  
M. Epstein ◽  
G. Olalde ◽  
S. Sante´n ◽  
...  
Keyword(s):  
Pilot Plant ◽  
Chemical Reactor ◽  
Packed Bed ◽  
Power Input ◽  
Energy Conversion Efficiency ◽  
Reaction Chamber ◽  
Solar Absorber ◽  
Optical Configuration ◽  
Reduction Of Zno ◽  
Eu Project

In the framework of the EU-project SOLZINC, a 300 kW solar chemical pilot plant for the production of zinc by carbothermic reduction of ZnO was experimentally demonstrated in a beam-down solar tower concentrating facility of Cassegrain optical configuration. The solar chemical reactor, featuring two cavities, of which the upper one is functioning as the solar absorber and the lower one as the reaction chamber containing a ZnO/C packed bed, was batch-operated in the 1300–1500 K range and yielded 50 kg/h of 95%-purity Zn. The measured energy conversion efficiency — ratio of the reaction enthalpy change to the solar power input — was 30%. Zinc finds application as a fuel for Zn-air batteries and fuel cells, and can also react with water to form high-purity hydrogen. In either case, the chemical product is ZnO, which in turn is solar-recycled to Zn. The SOLZINC process provides an efficient thermochemical route for the storage and transportation of solar energy in the form of solar fuels.

A 300kW Solar Chemical Pilot Plant for the Carbothermic Production of Zinc

2006 ◽  
Vol 129 (2) ◽  
pp. 190-196 ◽  
Author(s):  
C. Wieckert ◽  
U. Frommherz ◽  
S. Kräupl ◽  
E. Guillot ◽  
G. Olalde ◽  
...  
Keyword(s):  
Pilot Plant ◽  
Chemical Reactor ◽  
Packed Bed ◽  
Power Input ◽  
Energy Conversion Efficiency ◽  
Reaction Chamber ◽  
Solar Absorber ◽  
Optical Configuration ◽  
Reduction Of Zno ◽  
Eu Project

In the framework of the EU-project SOLZINC, a 300-kW solar chemical pilot plant for the production of zinc by carbothermic reduction of ZnO was experimentally demonstrated in a beam-down solar tower concentrating facility of Cassegrain optical configuration. The solar chemical reactor, featuring two cavities, of which the upper one is functioning as the solar absorber and the lower one as the reaction chamber containing a ZnO/C packed bed, was batch-operated in the 1300–1500 K range and yielded 50 kg/h of 95%-purity Zn. The measured energy conversion efficiency, i.e., the ratio of the reaction enthalpy change to the solar power input, was 30%. Zinc finds application as a fuel for Zn/air batteries and fuel cells, and can also react with water to form high-purity hydrogen. In either case, the chemical product is ZnO, which in turn is solar-recycled to Zn. The SOLZINC process provides an efficient thermochemical route for the storage and transportation of solar energy in the form of solar fuels.

scholarly journals Pulsed Gas Feeding for Stoichiometric Operation of a Gas-Solid Vortex Flow Solar Chemical Reactor

2001 ◽  
Author(s):  
Stefan Kräupl ◽  
Aldo Steinfeld
Keyword(s):  
Vortex Flow ◽  
Chemical Reactor ◽  
Thermal Conversion ◽  
Solar Furnace ◽  
Molar Ratio ◽  
Technical Solution ◽  
Molar Amount ◽  
Flux Concentration ◽  
Ch4 Reforming ◽  
Opening Up

Abstract The thermodynamic implications of conducting the solar combined ZnO-reduction and CH4-reforming under stoichiometric and non-stoichiometric conditions are examined. For a solar flux concentration ratio of 5000 and for a solar cavity-receiver operating at 1300 K, the solar thermal conversion efficiency is 55% for a stoichiometric molar ratio of ZnO and CH4, and decreases by 50% when using excess methane by a factor 10 over the stoichiometric molar amount. A technical solution for operating a gas-solid vortex-flow solar reactor under stoichiometric conditions was established by using a pulsed-feed of methane to carry out the particles of ZnO. Using this technique, nearly stoichiometric operation was demonstrated with a prototype reactor in a high-flux solar furnace, thereby opening up a means for efficient conversion of sunlight into chemical fuels.

Experimental Investigation of a Vortex-Flow Solar Chemical Reactor for the Combined ZnO-Reduction and CH4-Reforming*

2001 ◽  
Vol 123 (3) ◽  
pp. 237-243 ◽  
Author(s):  
Stefan Kra¨upl ◽  
Aldo Steinfeld
Keyword(s):  
Heat Transfer ◽  
Vortex Flow ◽  
Solar Power ◽  
Radiation Heat Transfer ◽  
Chemical Conversion ◽  
Chemical Reactor ◽  
Solar Furnace ◽  
Reaction Products ◽  
Ch4 Reforming ◽  
Reactor Operating

The co-production of Zn and synthesis gas by the combined reduction of ZnO and reforming of CH4 has been performed using a vortex-flow chemical reactor in a high-flux solar furnace. The reactor operating temperature ranged between 1221 and 1481 K for an input solar power of 2.3 to 4.6 kW and mean solar flux intensities of 810 to 1609 kW/m2. The performance of the reactor was determined by conducting a complete mass and energy balance for the chemical process. The chemical conversion ranged between 83–100 percent. The thermal efficiency, defined as the portion of input solar power absorbed as sensible and process heat, was in the range 11–28 percent. The exergy efficiency for the closed cycle, defined as the ratio of the maximum amount of work that the products leaving the reactor could produce if were re-combined to the input solar power, was in the range 0.3–3.1 percent. Major sources of energy loss are re-radiation heat transfer through the reactor aperture, conduction heat transfer through the reactor walls, and the quenching of the reaction products.

Pulsed Gas Feeding for Stoichiometric Operation of a Gas-Solid Vortex Flow Solar Chemical Reactor

2000 ◽  
Vol 123 (2) ◽  
pp. 133-137 ◽  
Author(s):  
Stefan Kra¨upl ◽  
Aldo Steinfeld
Keyword(s):  
Vortex Flow ◽  
Chemical Reactor ◽  
Thermal Conversion ◽  
Solar Furnace ◽  
Molar Ratio ◽  
Technical Solution ◽  
Molar Amount ◽  
Flux Concentration ◽  
Ch4 Reforming ◽  
Opening Up

The thermodynamic implications of conducting the solar combined ZnO-reduction and CH4-reforming under stoichiometric and non-stoichiometric conditions are examined. For a solar flux concentration ratio of 5000 and for a solar cavity-receiver operating at 1300 K, the solar thermal conversion efficiency is 55 percent for a stoichiometric molar ratio of ZnO and CH4, and decreases by 50 percent when using excess methane by a factor 10 over the stoichiometric molar amount. A technical solution for operating a gas-solid vortex-flow solar reactor under stoichiometric conditions was established by using a pulsed-feed of methane to carry out the particles of ZnO. Using this technique, nearly stoichiometric operation was demonstrated with a prototype reactor in a high-flux solar furnace, thereby opening up a means for efficient conversion of sunlight into chemical fuels.

Experimental Investigation of a Vortex-Flow Solar Chemical Reactor for the Combined ZnO-Reduction and CH4-Reforming

2001 ◽  
Author(s):  
Stefan Kräupl ◽  
Aldo Steinfeld
Keyword(s):  
Heat Transfer ◽  
Vortex Flow ◽  
Solar Power ◽  
Radiation Heat Transfer ◽  
Chemical Conversion ◽  
Chemical Reactor ◽  
Solar Furnace ◽  
Reaction Products ◽  
Ch4 Reforming ◽  
Reactor Operating

Abstract The co-production of Zn and synthesis gas by the combined reduction of ZnO and reforming of CH4 has been performed using a vortex-flow chemical reactor in a high-flux solar furnace. The reactor operating temperature ranged between 1032 and 1481 K for an input solar power of 2.3 to 4.6 kW and mean solar flux intensities of 810 to 1609 kW/m2. The performance of the reactor was determined by conducting a complete mass and energy balance for the chemical process. The chemical conversion ranged between 83–100%. The thermal efficiency, defined as the portion of input solar power absorbed as sensible and process heat, was in the range 11–28%. The exergy efficiency for the closed cycle, defined as the ratio of the maximum amount of work that the products leaving the reactor could produce if were re-combined to the input solar power, was in the range 0.3–3.1%. Major sources of energy loss are re-radiation heat transfer through the reactor aperture, conduction heat transfer through the reactor walls, and the quenching of the reaction products.

scholarly journals Biogas Dry Reforming for Hydrogen through Membrane Reactor Utilizing Negative Pressure

Fuels ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 194-209
Author(s):  
Akira Nishimura ◽  
Tomohiro Takada ◽  
Satoshi Ohata ◽  
Mohan Lal Kolhe
Keyword(s):  
Energy Source ◽  
Reaction Temperature ◽  
Negative Pressure ◽  
Membrane Reactor ◽  
Reaction Chamber ◽  
Dry Reforming ◽  
Molar Ratio ◽  
Effect Of Pressure ◽  
The Impact

Biogas, consisting of CH4 and CO2, is a promising energy source and can be converted into H2 by a dry reforming reaction. In this study, a membrane reactor is adopted to promote the performance of biogas dry reforming. The aim of this study is to investigate the effect of pressure of sweep gas on a biogas dry reforming to get H2. The effect of molar ratio of supplied CH4:CO2 and reaction temperature is also investigated. It is observed that the impact of psweep on concentrations of CH4 and CO2 is small irrespective of reaction temperature. The concentrations of H2 and CO increase with an increase in reaction temperature t. The concentration of H2, at the outlet of the reaction chamber, reduces with a decrease in psweep. It is due to an increase in H2 extraction from the reaction chamber to the sweep chamber. The highest concentration of H2 is obtained in the case of the molar ratio of CH4:CO2 = 1:1. The concentration of CO is the highest in the case of the molar ratio of CH4:CO2 = 1.5:1. The highest sweep effect is obtained at reaction temperature of 500 °C and psweep of 0.045 MPa.

Plasma-chemical synthesis of YBa2Cu3O7–y / CuO granular composites

2021 ◽  
pp. 32-37
Author(s):  
Igor Karpov ◽  
◽  
Anatoly Ushakov ◽  
Leonid Fedorov ◽  
Lylya Irtyugo ◽  
...  
Keyword(s):  
Chemical Synthesis ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Chemical Reactor ◽  
Reaction Chamber ◽  
Plasma Chemical ◽  
Plasma Chemical Reactor ◽  
Phase Synthesis ◽  
Pinning Centers ◽  
Granular Composites

The possibility of synthesizing HTSC ceramics in the reaction chamber of a plasma-chemical reactor is shown. The method allows one to significantly reduce the process of solid-phase synthesis and obtain modified HTSC ceramics with a given content of non-superconducting additives that act as pinning centers.

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