Begell House Inc.
International Journal of Energy for a Clean Environment
IJECE
2150-3621
4
2
2003
THE DEVOLATILIZATION STEP DURING THE FLUIDIZED BED CONVERSION OF A BIOMASS
16
10.1615/InterJEnerCleanEnv.v4.i2.10
Maria Laura
Mastellone
Department of Environmental, Biological and Pharmaceutical Sciences and Technologies DiSTABiF - Università della Campania "Luigi Vanvitelli" – Caserta, 81100 – Italy
F.
Perugini
Department of Environmental Sciences Second University of Naples Via Vivaldi 43 - 81100, Caserta, Italy
M.
Ponte
Department of Environmental Sciences Second University of Naples Via Vivaldi 43 - 81100, Caserta, Italy
Umberto
Arena
Department of Environmental Sciences Second University of Naples Via Vivaldi 43 - 81100, Caserta, Italy
A bubbling fluidized bed reactor (BFB) was batchwise operated under inert conditions to investigate phenomena occurring during the devolatilization of a biomass fuel, hazelnut shells coming from the food industry. A simple mathematical model was derived on the basis of some simplifying hypotheses suggested by the experimental evidence. The comparison between calculated and experimental values of devolatilization times and mass losses further support the assumptions made and the theoretical approach proposed.
EFFICIENCY ANALYSIS OF A BOILER FOR SUSPENSION BURNING OF SUGAR CANE BAGASSE
10
10.1615/InterJEnerCleanEnv.v4.i2.20
A. L.
Brito
University of Oriente, Facultad de Mecanica, Ave. De Las Americas s/n, Santiago de Cuba, 90900, Cuba
P.
Beaton
University of Zaragoza, Fluid Mechanics Group/LITEC, Maria de Luna, 3, Zaragoza, 50015, Spain
Javier
Ballester
University of Zaragoza, Fluid Mechanics Group/LITEC
Cesar
Dopazo
CIEMAT, Av. Complutense 22
Madrid, 28040 Spain
The present paper describes the results of the retrofitting of a bagasse-fired boiler (RETO CV-25-18) in the sugar mill "Amancio Rodriguez", located in Las Tunas, Cuba. The boiler was modified in order to implement a suspension-burning configuration.
Among other modifications, the distribution of combustion air along the furnace was redesigned in order to obtain a large-scale swirling-flow pattern above the grate. As a result, the new aerodynamic organization of the fuel-air mixture within the furnace was significantly improved.
The combustion efficiency of the boiler before and after the retrofitting is analyzed in this paper. The results of the analysis show that the gross efficiency calculated for the modified boiler increased by 1.91%. This difference is due mainly to the decrease of the heat losses by mechanical unburned matter from about 4% before the retrofitting to 1.95% with the new configuration.
ENVIRONMENTALLY FRIENDLY BUS TECHNOLOGIES
19
10.1615/InterJEnerCleanEnv.v4.i2.30
B.
Eberwein
Berliner Verkehrsbetriebe (BVG), Potsdamer Strasse 188, D-10783 Berlin, Germany
As the largest public transport operator in Germany, the Berliner Verkehrsbetriebe (BVG) is obliged to set standards, even in the area of environmental protection. This article provides information on how BVG meets this challenge by:
Implementing, testing, and demonstrating fuel cell vehicles;
Implementing sulfur-free city diesel buses;
Using Continuously Regenerating Trap (CRT) exhaust filters in the entire fleet;
Carrying out tests using aquazole fuel for buses;
Testing hybrid series busses.
MECHANISMS OF FIRE SUPPRESSION BY HALONS AND HALON REPLACEMENTS: A REVIEW
72
10.1615/InterJEnerCleanEnv.v4.i2.40
C. H.
Kim
Department of Aerospace Engineering, The University of Michigan, Ann Arbor, MI
O. C.
Kwon
Department of Aerospace Engineering, The University of Michigan, Ann Arbor, MI
G. M.
Faeth
Department of Aerospace Engineering, the University of Michigan, Ann Arbor, Michigan 48109-2140, USA
In spite of their effectiveness as flame suppressants, the manufacture of Halons was stopped in 1994 due to their large stratospheric ozone depletion capabilities, in order to comply with the Montreal Protocol. The resulting need for alternative flame suppressants has prompted extensive efforts to better understand flame suppression mechanisms and to develop environmentally acceptable Halon replacements. These efforts are reviewed in the present article, limited to flames involving either hydrogen or hydrocarbon fuels reacting with oxygen due to their relative tractability for detailed numerical simulations. The article begins with consideration of ozone chemistry in the stratosphere in order to highlight the transport and chemical reaction properties of flame suppressants that are responsible for ozone depletion. Recent experimental and computational studies of laminar premixed hydrogen-fueled flames are then considered in order to establish capabilities to predict the fundamental properties of these flames, e.g., their unstretched laminar burning velocities and their flame response to stretch as characterized by Markstein numbers. These results are then extended to consider effects of flame suppressants on the properties of laminar premixed hydrogen-fueled flames. The flame suppressant results show that they mainly function by reducing the concentrations of chain-carrying radicals (H and OH among others) in the reaction zone of flames with corresponding reduced reaction rates causing reduced laminar burning velocities and enhanced effects of extinction. An interesting corollary of this effect, however, is that reduced radical concentrations in the reaction zone also promotes preferential-diffusion/stretch instabilities that enhance flame reaction rates and tend to resist the action of flame suppressants. The new understanding of effects of flame suppressants on radical concentrations in flames is then exploited to gain a better understanding of the mechanism of flame suppression for both chemically-active and chemically-passive flame suppressants in both premixed and nonpremixed flames. These considerations help to identify the potential of various substances to act as effective flame suppressants but with negligible stratospheric ozone depletion potentials. Among these, water mist exhibits flame suppression capabilities potentially comparable to Halon 1301 but with little potential impact on the environment, including ozone depletion; therefore, additional study and development of methods of flame suppression by water mist clearly are merited.