N. Verdone - Academia.edu (original) (raw)

Papers by N. Verdone

Waste Management and the Environment VI, 2012

ABSTRACT Gasification has been identified as a key technology to enhance the environmental tolera... more ABSTRACT Gasification has been identified as a key technology to enhance the environmental tolerability of low quality fuels such as waste and biomass. In this work the performances of a laboratory scale gasification process fed with waste are reported. Among the several technical choices, we selected the up-draft fixed-bed gasifier as an interesting solution for heat generation in small-scale applications, due to the characteristics of simple geometry and low cost. The experimental setup is composed by an up-draft gasifier followed by a reactor used as filter to remove the particulate and as second thermal and catalytic stage to convert the produced tar in lighter species. A literature model has been adapted to the case under study to analyse the influence of operative parameters such as oxidant flow rate (equivalent and air/steam ratio values) and gasification temperature of the process. The original literature model considers the species gas evolution along the axial coordinate only, and does not include time dependency. To make the model time dependent, the consumption time of the gasification fuel bed estimated from experimental tests was introduced. Since the oxidation zone is below the gasification one, the initial species concentrations were set as the species concentrations produced at the end of the oxidation zone, calculated with an atom mass balance considering a complete char combustion. Since the model concerns only the gasification, the up-draft process was split into two consecutive steps to allow direct comparison between experimental and simulated data: first the drying and pyrolysis processes and then the fixed bed gasification. The model was successfully validated with experimental data and then it was used to predict the operative parameters that determine the optimal syngas composition. The best syngas composition (35%

Waste Management, 2007

Flue gas recirculation in the incinerator combustion chamber is an operative technique that offer... more Flue gas recirculation in the incinerator combustion chamber is an operative technique that offers substantial benefits in managing waste incineration. The advantages that can be obtained are both economic and environmental and are determined by the low flow rate of fumes actually emitted if compared to the flue gas released when recirculation is not conducted. Simulations of two incineration processes, with and without flue gas recirculation, have been carried out by using a commercial flowsheeting simulator. The results of the simulations demonstrate that, from an economic point of view, the proposed technique permits a greater level of energy recovery (up to +3%) and, at the same time, lower investment costs as far as the equipment and machinery constituting the air pollution control section of the plant are concerned. At equal treatment system efficiencies, the environmental benefits stem from the decrease in the emission of atmospheric pollutants. Throughout the paper reference is made to the EC legislation in the field of environmental protection, thus ensuring the general validity in the EU of the foundations laid and conclusions drawn henceforth. A numerical example concerning mercury emission quantifies the reported considerations and illustrates that flue gas recirculation reduces emission of this pollutant by 50%.

Chemical Engineering Science, 2002

... Brunner (1998) discussed in detail a roadmap for the development of countercurrent multistage... more ... Brunner (1998) discussed in detail a roadmap for the development of countercurrent multistage SFE ... order to avoid that CO 2 bubbled through the liquid without allowing a sufficient ... Their values, together with the correlation coefficient of the performed regression, are reported in ...

Bioresource Technology, 2009

Lab-scale experiments using a synthetic wastewater were carried out to assess the influence of di... more Lab-scale experiments using a synthetic wastewater were carried out to assess the influence of disk rotational speed on oxygen transfer rate in a RBC unit in the presence of biomass. The overall oxygen transfer coefficient (K L a) was computed. Five different disk rotational speeds were tested, in the typical RBC operating range (3-10 RPM). The soluble organic substrate was monitored through TOC analysis. Influent hydraulic organic loadings were in the range of 5.4-35.2 g TOC/m 2 d. The set of kinetic coefficients calculated fitting the experimental data by the selected model resulted in good agreement with the value reported in literature. A correlation for K L a as a function of disk rotational speed and disk diameter was obtained. Accordingly, a new expression of the enhancement factor of oxygen transfer was found, and compared to literature data.

IEEE Transactions on Energy Conversion, 1999

In this paper the authors present a feasibility study of a combined magnetohydrodynamic (MHD) and... more In this paper the authors present a feasibility study of a combined magnetohydrodynamic (MHD) and steam turbine plant in which the working gas is made of burnt plastic waste. The possibility of MHD retrofit of existing plant, especially fed by fossil fuel, is well known, and has been studied both for its economical and environmental benefits. The environmental impact and

Applied Catalysis A: General, 2010

Kinetics of methane steam reforming over a commercial nickel-based catalyst and over an innovativ... more Kinetics of methane steam reforming over a commercial nickel-based catalyst and over an innovative rhodium-perovskite catalyst of formula BaRh x Zr (1−x) O 3 was studied at atmospheric pressure and in the temperature range 723-1023 K. Extensive experimental runs were firstly carried out in a micro-reactor, with the catalysts in powder form, to evaluate their performances in steam methane reforming process. The behaviour of rhodium-perovskite catalyst was analyzed as function of steam-to-methane ratio and temperature, comparing the obtained performances of this catalyst with that showed by the commercial nickel-based one. Rhodium-perovskite catalyst shows higher activity for steam methane reforming reaching methane conversions higher than those obtained with the nickel-based catalyst and closer to the thermodynamic equilibrium value. Based on a detailed review of the kinetic models proposed for steam reforming, the experimental data were fitted using a simple kinetic model where the conversion of methane is proportional only to the methane partial pressure. Good agreement was obtained between the experimental data and the kinetic model prediction.

Waste Management and the Environment VI, 2012

ABSTRACT Gasification has been identified as a key technology to enhance the environmental tolera... more ABSTRACT Gasification has been identified as a key technology to enhance the environmental tolerability of low quality fuels such as waste and biomass. In this work the performances of a laboratory scale gasification process fed with waste are reported. Among the several technical choices, we selected the up-draft fixed-bed gasifier as an interesting solution for heat generation in small-scale applications, due to the characteristics of simple geometry and low cost. The experimental setup is composed by an up-draft gasifier followed by a reactor used as filter to remove the particulate and as second thermal and catalytic stage to convert the produced tar in lighter species. A literature model has been adapted to the case under study to analyse the influence of operative parameters such as oxidant flow rate (equivalent and air/steam ratio values) and gasification temperature of the process. The original literature model considers the species gas evolution along the axial coordinate only, and does not include time dependency. To make the model time dependent, the consumption time of the gasification fuel bed estimated from experimental tests was introduced. Since the oxidation zone is below the gasification one, the initial species concentrations were set as the species concentrations produced at the end of the oxidation zone, calculated with an atom mass balance considering a complete char combustion. Since the model concerns only the gasification, the up-draft process was split into two consecutive steps to allow direct comparison between experimental and simulated data: first the drying and pyrolysis processes and then the fixed bed gasification. The model was successfully validated with experimental data and then it was used to predict the operative parameters that determine the optimal syngas composition. The best syngas composition (35%

Waste Management, 2007

Flue gas recirculation in the incinerator combustion chamber is an operative technique that offer... more Flue gas recirculation in the incinerator combustion chamber is an operative technique that offers substantial benefits in managing waste incineration. The advantages that can be obtained are both economic and environmental and are determined by the low flow rate of fumes actually emitted if compared to the flue gas released when recirculation is not conducted. Simulations of two incineration processes, with and without flue gas recirculation, have been carried out by using a commercial flowsheeting simulator. The results of the simulations demonstrate that, from an economic point of view, the proposed technique permits a greater level of energy recovery (up to +3%) and, at the same time, lower investment costs as far as the equipment and machinery constituting the air pollution control section of the plant are concerned. At equal treatment system efficiencies, the environmental benefits stem from the decrease in the emission of atmospheric pollutants. Throughout the paper reference is made to the EC legislation in the field of environmental protection, thus ensuring the general validity in the EU of the foundations laid and conclusions drawn henceforth. A numerical example concerning mercury emission quantifies the reported considerations and illustrates that flue gas recirculation reduces emission of this pollutant by 50%.

Chemical Engineering Science, 2002

... Brunner (1998) discussed in detail a roadmap for the development of countercurrent multistage... more ... Brunner (1998) discussed in detail a roadmap for the development of countercurrent multistage SFE ... order to avoid that CO 2 bubbled through the liquid without allowing a sufficient ... Their values, together with the correlation coefficient of the performed regression, are reported in ...

Bioresource Technology, 2009

Lab-scale experiments using a synthetic wastewater were carried out to assess the influence of di... more Lab-scale experiments using a synthetic wastewater were carried out to assess the influence of disk rotational speed on oxygen transfer rate in a RBC unit in the presence of biomass. The overall oxygen transfer coefficient (K L a) was computed. Five different disk rotational speeds were tested, in the typical RBC operating range (3-10 RPM). The soluble organic substrate was monitored through TOC analysis. Influent hydraulic organic loadings were in the range of 5.4-35.2 g TOC/m 2 d. The set of kinetic coefficients calculated fitting the experimental data by the selected model resulted in good agreement with the value reported in literature. A correlation for K L a as a function of disk rotational speed and disk diameter was obtained. Accordingly, a new expression of the enhancement factor of oxygen transfer was found, and compared to literature data.

IEEE Transactions on Energy Conversion, 1999

In this paper the authors present a feasibility study of a combined magnetohydrodynamic (MHD) and... more In this paper the authors present a feasibility study of a combined magnetohydrodynamic (MHD) and steam turbine plant in which the working gas is made of burnt plastic waste. The possibility of MHD retrofit of existing plant, especially fed by fossil fuel, is well known, and has been studied both for its economical and environmental benefits. The environmental impact and

Applied Catalysis A: General, 2010

Kinetics of methane steam reforming over a commercial nickel-based catalyst and over an innovativ... more Kinetics of methane steam reforming over a commercial nickel-based catalyst and over an innovative rhodium-perovskite catalyst of formula BaRh x Zr (1−x) O 3 was studied at atmospheric pressure and in the temperature range 723-1023 K. Extensive experimental runs were firstly carried out in a micro-reactor, with the catalysts in powder form, to evaluate their performances in steam methane reforming process. The behaviour of rhodium-perovskite catalyst was analyzed as function of steam-to-methane ratio and temperature, comparing the obtained performances of this catalyst with that showed by the commercial nickel-based one. Rhodium-perovskite catalyst shows higher activity for steam methane reforming reaching methane conversions higher than those obtained with the nickel-based catalyst and closer to the thermodynamic equilibrium value. Based on a detailed review of the kinetic models proposed for steam reforming, the experimental data were fitted using a simple kinetic model where the conversion of methane is proportional only to the methane partial pressure. Good agreement was obtained between the experimental data and the kinetic model prediction.