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.

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.

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.

Operational Performance of a 5-kW Solar Chemical Reactor for the Co-Production of Zinc and Syngas

2003 ◽  
Vol 125 (1) ◽  
pp. 124-126 ◽  
Author(s):  
Stefan Kra¨upl ◽  
Aldo Steinfeld
Keyword(s):  
Vortex Flow ◽  
Fossil Fuel ◽  
Chemical Conversion ◽  
Chemical Reactor ◽  
Energy Conversion Efficiency ◽  
Operational Performance ◽  
Residence Times ◽  
Direct Irradiation ◽  
Mean Residence Times ◽  
Ch4 Reforming

We report on the improved operational performance and energy conversion efficiency of a 5-kW solar chemical reactor for the combined ZnO-reduction and CH4-reforming SynMet process. The reactor features a pulsed vortex flow of CH4 laden with ZnO particles, which is confined to a cavity-receiver and directly exposed to solar power fluxes exceeding 2000kW/m2. Reactants were continuously fed at ambient temperature, heated by direct irradiation to above 1350°K, and converted to Zn and syngas during mean residence times of 10 seconds. Typical chemical conversion attained was 100% for ZnO and up to 96% for CH4. The thermal efficiency was in the 15–22% range; the exergy efficiency reached up to 7.7% and may be increased by recovering the sensible and latent heat of the products. The SynMet process avoids emissions of greenhouse-gases and other pollutant derived from the traditional fossil-fuel-based production of zinc and syngas, and further converts solar energy into storable and transportable chemical fuels.

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.

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.

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.

Operational Performance of a 5 kW Solar Chemical Reactor for the Co-Production of Zinc and Syngas

Solar Energy ◽  
2002 ◽  
Author(s):  
Stefan Kra¨upl ◽  
Aldo Steinfeld
Keyword(s):  
Vortex Flow ◽  
Fossil Fuel ◽  
Chemical Conversion ◽  
Chemical Reactor ◽  
Energy Conversion Efficiency ◽  
Operational Performance ◽  
Residence Times ◽  
Direct Irradiation ◽  
Mean Residence Times ◽  
Ch4 Reforming

We report on the improved operational performance and energy conversion efficiency of a 5 kW solar chemical reactor for the combined ZnO-reduction and CH4-reforming “SynMet” process. The reactor features a pulsed vortex flow of CH4 laden with ZnO particles, which is confined to a cavity-receiver and directly exposed to solar power fluxes exceeding 2000 kW/m2. Reactants were continuously fed at ambient temperature, heated by direct irradiation to above 1350 K, and converted to Zn(g) and syngas during mean residence times of 10 seconds. Typical chemical conversion attained was 100% to Zn and up to 96% to syngas. The thermal efficiency was in the 15–22% range; the exergy efficiency reached up to 7.7% and may be increased by recovering the sensible and latent heat of the products. The Synmet process avoids emissions of greenhouse-gases and other pollutant derived from the traditional fossil-fuel-based production of zinc and syngas, and further converts solar energy into storable and transportable chemical fuels.

Calcium pyrophosphate powder synthesized from phosphoric acid and calcium carbonate

2020 ◽  
pp. 42-48
Author(s):  
Tatiana Safronova ◽  
◽  
Tatiana Shatalova ◽  
Snezhana Tikhonova ◽  
Yaroslav Filippov ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Phosphoric Acid ◽  
Functional Materials ◽  
Bone Defects ◽  
Thermal Conversion ◽  
Calcium Pyrophosphate ◽  
Molar Ratio

Powders of calcium pyrophosphate Ca2P2O7 in the form of γ- и β-modifications have been produced as a result of thermal conversion of brushite CaHPO4∙2H2O synthesized from phosphoric acid H3PO4 and calcium carbonate CaCO3 at the molar ratio P / Ca = 1.1. The resulting powders can be used for production of various functional materials including biocompatible and bioresorbable ones for the treatment of bone defects.

scholarly journals Dimensioning of vortex storm overflows

2018 ◽  
Vol 78 (2) ◽  
pp. 259-265 ◽  
Author(s):  
Szymon Mielczarek ◽  
Jerzy M. Sawicki
Keyword(s):  
Vortex Flow ◽  
Kinematic Model ◽  
Morning Glory ◽  
Technical Solution ◽  
Laboratory Measurements ◽  
Inlet Stream ◽  
Liquid Free Surface ◽  
Mathematical Relations ◽  
Sewage Systems ◽  
Bottom Outlet

Abstract Vortex storm overflow is an interesting and useful technical solution, especially important in storm and combined sewage systems. However, there are no methods of this device dimensioning, which would be mathematically simple and properly precise physically. Such a method has been proposed in this paper, on the basis of investigations performed for the vortex separators and vortex flow controls. The essence of this method relies on the kinematic model of the velocity field and energy balance of the inflowing stream and dissipation. The procedure enables specialists to calculate the rise of the liquid free surface caused by the inlet stream energy and the hydraulic resistance of the bottom outlet. These mathematical relations are completed by two formulae: for the bottom ‘morning glory’ sink and for the upper overflow. The model has been positively verified during the laboratory measurements, so can be used during the technical dimensioning of the vortex storm overflows.

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