Synthesis of SiC powder by RF plasma technique
Z. Károly1*, I. Mohai1, Sz. Klébert1, A. Keszler1, I.E. Sajó2, J. Szépvölgyi1,3
1Institute of Materials and Environmental Chemistry, Chemical Research Center, HAS, Budapest, Hungary
2Chemical Research Center, Hungarian Academy of Sciences, Budapest, Hungary
3Research Institute of Chemical and Process Engineering, University of Pannonia, Hungary
Powder Technology, 214, 2011, 300–305
Abstract
Continuous synthesis of SiC nanoparticles by RF thermal plasma method has been studied. Precursor mixtures comprised commercial silica powder and various types of carbon source including graphite, char, carbon black as well as the carbonaceous residue of tire pyrolyses. The obtained SiC consisted of nanosized particles that were crystallized mainly in β phase with traces of α. The conversion rate of the silica precursor to SiC varied between 60% and 73% depending on the type of carbonaceous material and on the carbon excess. The main obstacle to achieve higher conversion is the rapid cooling of reactive species that can also be attributed to formation of nanosized particles.
© 2011 Elsevier B.V. All rights reserved.
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Experimental results of gasification of waste tire with air&CO2, air&steam and steam in a bubbling fluidized bed gasifier
Hakan Karatas*, Hayati Olgun, Fehmi Akgun
TUBITAK Marmara Research Center, Energy Institute, Gebze, Kocaeli, Turkey
Fuel Processing Technology, 102, 2012, 166–174
Abstract
Gasification is one of the thermochemical conversion methods to produce both product gas and solid char. The quality of the product gas widely differs depending on the type of the gasification agent used in the gasification process. Therefore, one of the important parameters in the design phase of the gasification system is the gasification agent. In the present study, a laboratory scale bubbling fluidized bed gasifier was used to gasify the waste tire with the gasification agents of air&CO2, air&steam and steam. Within this frame, the effects of gasification agents, bed material particle size, CO2 to air ratio, steam to air ratio, steam temperature and steam to fuel ratio on the quality of the product gas were investigated. In order to determine the composition of the product gas, an online gas analyzer, which can measure CO, CO2, CH4, H2 and O2 components, was used. By using the measured gas compositions, the lower heating value (LHV) was calculated to represent the quality of the product gas. Comparing the gasification agents of air&CO2, air&steam and steam, the LHV of the product gas was obtained 9.59, 7.34 and 15.21 MJ/Nm3, respectively. The repetition and uncertainty calculation of the tests were performed.
© 2012 Elsevier B.V. All rights reserved.
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Optimizing Argon Recovery: Membrane Separation of Carbon Monoxide at High Concentrations via the Water Gas Shift
Thomas Harlacher*, Marco Scholz, Thomas Melin, Matthias Wessling
RWTH Aachen University, Chemical Process Engineering, Aachen, Germany
Industrial & Engineering Chemistry Research, 51 (38), 2012, 12463–12470
Abstract
This paper investigates the feasibility of separating carbon monoxide at high concentrations from argon in silicon carbide production by using five commercial polymer membranes. Single gas and mixed gas experiments are reported and compared to module simulation. Three possible process routes with a membrane gas separation incorporated were studied: direct CO removal, methanation, and the water gas shift reaction. The latter proved to be the most promising membrane process route. While a polyether-based Polyactive (PEO) membrane separated CO2 best, polyimide membranes (PI) could separate both CO2 and H2 from argon but required a 10-time greater membrane area. In conclusion, carbon monoxide can be effectively separated from argon in the percentage concentration range via the water gas shift reaction and subsequent separation of the resulting CO2 and H2 using both cited membranes. However, since there was a trade-off between separation performance and required membrane area, future membrane processes should comprise both PEO and PI to ensure optimal argon recovery.
© 2012 American Chemical Society.
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Steam gasification of waste tyre: Influence of process temperature on yield and product composition
S. Portofino1*, A. Donatelli2, P. Iovane2, C. Innella2, R. Civita2, M. Martino2, D. A. Matera2, A. Russo2, G. Cornacchia2, S. Galvagno1
1UTTP NANO – C.R. ENEA Portici, Italy
2UTTTRI RIF – C.R. ENEA Trisaia, Italy
Waste Management, 2012
Abstract
An experimental survey of waste tyre gasification with steam as oxidizing agent has been conducted in a continuous bench scale reactor, with the aim of studying the influence of the process temperature on the yield and the composition of the products; the tests have been performed at three different temperatures, in the range of 850–1000 °C, holding all the other operational parameters (pressure, carrier gas flow, solid residence time). The experimental results show that the process seems promising in view of obtaining a good quality syngas, indicating that a higher temperature results in a higher syngas production (86 wt%) and a lower char yield, due to an enhancement of the solid–gas phase reactions with the temperature. Higher temperatures clearly result in higher hydrogen concentrations: the hydrogen content rapidly increases, attaining values higher than 65% v/v, while methane and ethylene gradually decrease over the range of the temperatures; carbon monoxide and dioxide instead, after an initial increase, show a nearly constant concentration at 1000 °C. Furthermore, in regards to the elemental composition of the synthesis gas, as the temperature increases, the carbon content continuously decreases, while the oxygen content increases; the hydrogen, being the main component of the gas fraction and having a small atomic weight, is responsible for the progressive reduction of the gas density at higher temperature.
© 2012 Elsevier B.V. All rights reserved.
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Experimental results of gasification of waste tire with air in a bubbling fluidized bed gasifier
Hakan Karatas*, Hayati Olgun, Berrin Engin, Fehmi Akgun
TUBITAK Marmara Research Center, Energy Institute, Gebze, Kocaeli, Turkey
Fuel, 105, 2013, 566–571
Abstract
Waste tire can be thermochemically disposed to solve environmental problems and to produce energy. Gasification is one of the methods to obtain a product gas with a high calorific value. The product gas is a potential resource for electrical energy production. This paper presents the experimental results of gasification of waste tire in a fluidized bed under air atmosphere. The effects of equivalence ratio (ER), gasification temperature and bed material particle size on the composition of the product gas are investigated. The equivalence ratio is varied in the range of 0.15–0.45. The composition of the product gas is determined with an online gas analyzer which measures CO, CO2, CH4, H2 and O2 components. The lower heating value (LHV) of the product gas is calculated by using the gas composition measurements. Lower ER values result in lower CO2 concentrations, higher CH4 and H2 concentrations and higher LHVs. This study shows the importance of gasification temperature at low ER values, produces data points for four bed material particle sizes to verify the relation between LHV and ER, and proposes generalized correlations for different ER ranges.
© 2012 Elsevier Ltd. All rights reserved.
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