This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
European Biomass Conference and Exhibition Proceedings, 2019
This study analyzes the conversion characteristics of two agricultural residues (vineyard and oli... more This study analyzes the conversion characteristics of two agricultural residues (vineyard and olive pruning) in form of pellets and draws a comparison with the same fuels submitted to a thermal treatment, i.e., torrefaction. The combustion characteristics are measured through the burning rate and temperatures reached. Afterwards, ash and its sintered fractions are studied to determine problems related to fouling and sintering that may cause clogging of mechanical parts in conversion equipment. The torrefied fuels have shown some improvement regarding ash behavior, especially, a reduction of sintered fractions. However, the behavior of both biomasses can be very diverse in some regards. Additionally, the results of predictive indices have proven inconclusive regarding the prediction of sintering and fouling problems. This highlights the complexity of agricultural biomass respect to forest biomass (e.g., pine) and the necessity to evaluate fuels from agricultural residues.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Agricultural residual biomass has great potential as an energy source, but is used only to a limi... more Agricultural residual biomass has great potential as an energy source, but is used only to a limited extent mainly because of the characteristics of its ash (quantity and composition), which can lead to problematic phenomena during combustion, among them fly ash deposition, the focus of this study. A previous work presented the results of laboratory experiments carried out using a fixed-grate reactor and involving four different agropellets under different operating conditions; the variables tested were deposition rate, bottom ash proportion and sintering degree during combustion. Based on these results, the analysis has been taken further and the fly ash deposits collected during these tests have been characterized by SEM-EDS and XRD. A methodology to differentiate between deposits caused by condensation (including thermophoresis and turbulent diffusion) and by inertial impact of coarse fly ash entrained from the bed has been proposed. Deposition by condensation has been found to decrease for higher values of excess air ratio in all cases. Conversely, deposition by inertial impact does not show a common behavior, due to the influence of bottom ash sintering degree and fuel composition. The ultimate aim of this study is to gain a better understanding of fly ash deposition, in order to develop better fuel blends, boiler design and operating parameters, enhancing the market penetration of agricultural residual biomass.
Agricultural residual biomass presents a high potential for energy use around the world, often no... more Agricultural residual biomass presents a high potential for energy use around the world, often not utilized to a large extent due to its significant differences with respect to other biomass types, such as the one of forest origin. These differences are mainly related to the characteristics of its ashes (quantity and composition) which increase certain problematic phenomena during combustion, among them bottom ash sintering and fly ash deposition. The main goal of this paper is the experimental study of these issues for four different agropellets made of residual agricultural biomass (one woody and three blended with an herbaceous component) and a forest wood pellet (used as a reference), evaluated under different operating conditions in a laboratory fixed bed reactor. The influence of inlet air flow and temperature on the sintering degree and deposition ratio has been analyzed in a systematic way. For the five biofuels, under tested conditions, a clear relation inversely proportional between air excess ratio and deposition ratio has been determined. Deposition was more substantial for the four agropellets; meanwhile the sintering degree was more important for the three with an herbaceous component. The information obtained in this research work is intended to help researchers and technologists to make choices regarding the design and operation of conversion systems adapted for agricultural residual biomass, enhancing its market penetration.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
European Biomass Conference and Exhibition Proceedings, 2019
This study analyzes the conversion characteristics of two agricultural residues (vineyard and oli... more This study analyzes the conversion characteristics of two agricultural residues (vineyard and olive pruning) in form of pellets and draws a comparison with the same fuels submitted to a thermal treatment, i.e., torrefaction. The combustion characteristics are measured through the burning rate and temperatures reached. Afterwards, ash and its sintered fractions are studied to determine problems related to fouling and sintering that may cause clogging of mechanical parts in conversion equipment. The torrefied fuels have shown some improvement regarding ash behavior, especially, a reduction of sintered fractions. However, the behavior of both biomasses can be very diverse in some regards. Additionally, the results of predictive indices have proven inconclusive regarding the prediction of sintering and fouling problems. This highlights the complexity of agricultural biomass respect to forest biomass (e.g., pine) and the necessity to evaluate fuels from agricultural residues.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Agricultural residual biomass has great potential as an energy source, but is used only to a limi... more Agricultural residual biomass has great potential as an energy source, but is used only to a limited extent mainly because of the characteristics of its ash (quantity and composition), which can lead to problematic phenomena during combustion, among them fly ash deposition, the focus of this study. A previous work presented the results of laboratory experiments carried out using a fixed-grate reactor and involving four different agropellets under different operating conditions; the variables tested were deposition rate, bottom ash proportion and sintering degree during combustion. Based on these results, the analysis has been taken further and the fly ash deposits collected during these tests have been characterized by SEM-EDS and XRD. A methodology to differentiate between deposits caused by condensation (including thermophoresis and turbulent diffusion) and by inertial impact of coarse fly ash entrained from the bed has been proposed. Deposition by condensation has been found to decrease for higher values of excess air ratio in all cases. Conversely, deposition by inertial impact does not show a common behavior, due to the influence of bottom ash sintering degree and fuel composition. The ultimate aim of this study is to gain a better understanding of fly ash deposition, in order to develop better fuel blends, boiler design and operating parameters, enhancing the market penetration of agricultural residual biomass.
Agricultural residual biomass presents a high potential for energy use around the world, often no... more Agricultural residual biomass presents a high potential for energy use around the world, often not utilized to a large extent due to its significant differences with respect to other biomass types, such as the one of forest origin. These differences are mainly related to the characteristics of its ashes (quantity and composition) which increase certain problematic phenomena during combustion, among them bottom ash sintering and fly ash deposition. The main goal of this paper is the experimental study of these issues for four different agropellets made of residual agricultural biomass (one woody and three blended with an herbaceous component) and a forest wood pellet (used as a reference), evaluated under different operating conditions in a laboratory fixed bed reactor. The influence of inlet air flow and temperature on the sintering degree and deposition ratio has been analyzed in a systematic way. For the five biofuels, under tested conditions, a clear relation inversely proportional between air excess ratio and deposition ratio has been determined. Deposition was more substantial for the four agropellets; meanwhile the sintering degree was more important for the three with an herbaceous component. The information obtained in this research work is intended to help researchers and technologists to make choices regarding the design and operation of conversion systems adapted for agricultural residual biomass, enhancing its market penetration.
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