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Experimental investigations on a 20 kWe, solid biomass gasification system

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Abstract

When the objective is to generate motive or electric power via I.C. engine, the overall pressure drop through the suction gasification system in addition to gas quality has become a sensitive issue. This work, therefore, presents an experimental study on a suction gasifier (downdraft) arrangement operating on kiker wood or Acacia nilotica (L). Studies were conducted to investigate the influence of fluid flow rate on pressure drop through the gasifier system for ambient isothermal airflow and ignited mode, pumping power, and air-fuel ratio, gas composition and gasification efficiency. Results of pressure drop, temperature profile, gas composition or calorific value are found to be sensitive with fluid flow rate. Ignited gasifier gives much higher pressure drop when compared against newly charged gasifier bed with isothermal ambient airflow. Higher reaction temperatures in gasifier tends to enhance gasifier performance, while, overall pressure drop and thus pumping power through the system increases. Both ash accumulated gasifier bed and sand bed filters with tar laden quartz particles also show much higher pressure drops.

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... In dual fuel mode, the producer gas obtained from gasifiers is utilized as primary gaseous fuel while pilot diesel is used to initiate combustion. The engine conversion for operation in dual fuel mode demands minor modifications and allows flexibility to revert back in pure diesel mode, if required [1][2][3][4]. However, dual fuel engine technology still needs fossil fuel to run the engine. ...
... Researchers succeeded in breakdown the barrier of using high compression ratio. They demonstrated smooth and efficient engine operation up to compression ratio of 17 without any autoignition tendency on a 20 kW engine [2,3]. Shashikantha and Parikh [7] modified a CI engine to operate purely on producer gas at the compression ratio of 11.5 and spark time was optimized at 35 . ...
... Med. 12,[1][2][3][4][5] 2020 ...
Article
Decentralized power supply for remote and urban areas via gasifier-engine system is an attractive choice especially when sources of fossil fuel are getting depleted and leading to serious emission hazards. In gasifier, the solid biomass is converted into “producer gas,” which can fuel a gas-engine in single fuel mode i.e., complete substitution. The conversion of stationary diesel engine into producer gas-engine (i.e., complete substitution) ensure complete independency from fossil fuels; although it demands major modifications/retrofitting arrangements. Herein, an existing diesel engine of capacity 7.4 kW is chosen and converted into producer gas-engine operated on single fuel mode (spark ignited) at compression ratio of 14:1. Other arrangements such as installation of spark ignited mode (i.e., ignition coil and distributor followed by contact breaker unit), gasoline carburetor and special induction system followed by other necessary arrangements were carried out. A kit is suggested for conversion of different capacity and types engines utilizing alternate/renewable gaseous fuels. A considerable power loss (power derating) and reduction in thermal efficiency is observed while operation in single producer gas mode. More detailed experiments are required to predict qualitative performance trends.
... The cupola data would be collected but gasifier is not to be tested in this study. Instead, performance and operational data will be borrowed from the work of Sharma, for an already tested and analysed 20 kWe, Solid Biomass Downdraft Gasifier [9]. At the end of this study, the possibility of cutting down coke consumption in cupola by hybridizing with a biomass gassifier would be shown by means of analyzing energy efficiency. ...
... All the heat generated can be channeled through a duct integrated to the gasifier. All the necessary experimental data has already been generated by Sharma [9], based on model with the same configuration. The photograph view of the gasifier can also be seen in figure 5 as provided by Sharma [9]. ...
... All the necessary experimental data has already been generated by Sharma [9], based on model with the same configuration. The photograph view of the gasifier can also be seen in figure 5 as provided by Sharma [9]. The solid fuel used as source of energy in the gasifier by Sharma [9], was sun dried Kiker wood (Acacia nilotica). ...
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The energy efficiency of any foundry largely resides on efficiency of the melting process. High price and limited supply of coke will continue to press the need for devising a way to cut down its demand or developing more energy-efficient solutions for the melting process. This work tries to address the issue by proposing and analyzing a way of reducing coke consumption in a foundry cupola studied, by hybridizing it with biomass wood gasifier. Wood fuel is very cheap and readily available. It can be used to heat the blast air going through a cupola furnace by burning in a gasifier. 800 °C of gas at 16 g/s will be available to heat up the blast air entering the studied cupola of Asia Sewing Machine's foundry to at least 475 °C if hybridized with the 20 KWe downdraft biomass gasifier model studied by Sharma. This is enough to cut down the coke consumption by 133 Kg from 430 Kg used to melt 3450 Kg of metal charge at present. Analysis has shown the coke energy efficiency to improve from 43% to 62.4%. The stoichemetric air/fuel ratio required for both the gasifier and the cupola is found to be 7.86 and 10.52 respectively for proper combustion of their respective fuel. The chemistry in the various stages of the cupola furnace and reasons for that huge percentage of heat energy loss during melting process was properly discussed. It is possible to achieve a less coke demanding cupola furnace by hybridizing with a biomass gasifier. This would greatly reduce the amount of coke consumption in a foundry by using a cheaper and more readily available energy source that consumes gradually to supply a hot air blast (wood etc).
... Bradley (5) argumenta que es una especie de origen Neotropical, mientras Green (15) afirma que fue introducida en América procedente de la Isla Reunión en el océano Índico. En Brasil es considerada como la principal plaga del café (12,27,32), por su ocurrencia generalizada y a los perjuicios económicos causados (12,26), los cuales pueden llegar hasta un 50% de pérdidas en producción (20), debido a que todas las variedades de Coffea arabica cultivadas en Brasil son susceptibles a este insecto (16). Existen reportes de poblaciones de este insecto resistentes a insecticidas que son usados para controlarlo; Alves et al. (2) encontraron resistencia de L. coffeella a organofosforados, especialmente clorpirifos, con una frecuencia de insectos resistentes <12%. ...
... La biología de este insecto ha sido estudiada por diversos autores (29, 32, 33, 35), quienes determinaron que el desarrollo del insecto de huevo a adulto puede variar de acuerdo a la variedad de café en la que se desarrolla, así como a las condiciones de temperatura, humedad relativa y precipitación pluviométrica. Los resultados con relación a la duración del ciclo de huevo a adulto reportados en la literatura, pueden variar entre 19 y 87 días, encontrándose como un rango favorable de temperatura para el desarrollo del insecto de 22 a 28°C (12,13,26,27,32). Trabajos adelantados en Brasil por Parra (26) y Magalhães et al. (19), evaluando diferentes genotipos del género Coffea, determinaron que la biología, sobrevivencia y fecundidad del insecto se ve afectada por el genotipo de Coffea en que se desarrolla y se atribuye a las diferencias de alcaloides y fenoles presentes en las hojas. ...
... El desempeño de un gasificador es afectado principalmente por el tipo y condiciones de la biomasa (contenido de humedad, tamaño y densidad), flujo de la biomasa, agente oxidante utilizado y flujo y relación de equivalencia (kg de aire/kg de biomasa suministrado y kg de aire/kg de biomasa estequiométrico) (10,12,14,27). ...
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New products causing adverse effects on coffee berry borer, such as mortality, repellence, decreasing reproductive capacity or affecting metamorphosis on immature stages, are sought constantly; however, the methods currently used to test new products are directed to evaluate adult mortality, so for giving disadvantages to those having other effects. The objective of this research was to develop methodologies that allow evaluating different biological effects of new products on coffee berry borer in laboratory conditions, reducing time and costs. We tested two methods employing disinfected unripe coffee berries. In order to determine a disinfecting procedure, we evaluated different treatments, selecting as better option to immerse coffee berries in 0.5% sodium hypochlorite then to UV irradiate during 15 minutes. Besides, bioassays to establish infesting conditions that allows berry borer adults to remain in a penetration position on the coffee berry surface were accomplished. To do so, we obtained the condition above mentioned after five hours of releasing borers on coffee berries at 21 °C. Furthermore, two methodologies were used to evaluate the contact effects or ingestion effect of new products on coffee berry borer, giving close approximation to field results.
... Bradley (5) argumenta que es una especie de origen Neotropical, mientras Green (15) afirma que fue introducida en América procedente de la Isla Reunión en el océano Índico. En Brasil es considerada como la principal plaga del café (12,27,32), por su ocurrencia generalizada y a los perjuicios económicos causados (12,26), los cuales pueden llegar hasta un 50% de pérdidas en producción (20), debido a que todas las variedades de Coffea arabica cultivadas en Brasil son susceptibles a este insecto (16). Existen reportes de poblaciones de este insecto resistentes a insecticidas que son usados para controlarlo; Alves et al. (2) encontraron resistencia de L. coffeella a organofosforados, especialmente clorpirifos, con una frecuencia de insectos resistentes <12%. ...
... La biología de este insecto ha sido estudiada por diversos autores (29, 32, 33, 35), quienes determinaron que el desarrollo del insecto de huevo a adulto puede variar de acuerdo a la variedad de café en la que se desarrolla, así como a las condiciones de temperatura, humedad relativa y precipitación pluviométrica. Los resultados con relación a la duración del ciclo de huevo a adulto reportados en la literatura, pueden variar entre 19 y 87 días, encontrándose como un rango favorable de temperatura para el desarrollo del insecto de 22 a 28°C (12,13,26,27,32). Trabajos adelantados en Brasil por Parra (26) y Magalhães et al. (19), evaluando diferentes genotipos del género Coffea, determinaron que la biología, sobrevivencia y fecundidad del insecto se ve afectada por el genotipo de Coffea en que se desarrolla y se atribuye a las diferencias de alcaloides y fenoles presentes en las hojas. ...
... El desempeño de un gasificador es afectado principalmente por el tipo y condiciones de la biomasa (contenido de humedad, tamaño y densidad), flujo de la biomasa, agente oxidante utilizado y flujo y relación de equivalencia (kg de aire/kg de biomasa suministrado y kg de aire/kg de biomasa estequiométrico) (10,12,14,27). ...
Article
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Con el objeto de encontrar alternativas para la remoción enzimática de sedimentos en extractos concentrados de café, se evaluó la producción de una mananasa clonada a partir del genoma de la broca del café (Hypothenemus hampei) y su uso en la hidrólisis de los galactomananos que componen estos sedimentos. La producción de la mananasa se hizo mediante fermentaciones en biorreactor con una cepa de Pichia pastoris, previamente recombinada con el gen de la mananasa de la broca. Se evaluaron tres medios de cultivo y de cada fermentación se purificó la mananasa mediante cromatografía de afinidad. La actividad enzimática se verificó mediante una prueba de hidrólisis con galactomanano purificado de semillas de café. Se evaluó la actividad enzimática de la mananasa recombinante junto con otras enzimas comerciales, utilizando como substrato el galactomanano puro. La actividad enzimática se calculó midiendo la cantidad de manosa producida en función del tiempo y la cantidad de enzima utilizada. La mananasa de la broca mostró la mayor actividad enzimática. Se evaluó el porcentaje de remoción de sedimentos en extractos concentrados de café mediante hidrólisis enzimática con la mananasa de la broca en comparación con otras enzimas comerciales. La incubación de los extractos con la mananasa de la broca logró el 95% de remoción de sedimentos en comparación con el 66% y 33% de remoción con otras enzimas. El uso de esta mananasa es una alternativa para la remoción de sedimentos en el proceso de industrialización del café, sin afectar la calidad sensorial del extracto.
... Bradley (5) argumenta que es una especie de origen Neotropical, mientras Green (15) afirma que fue introducida en América procedente de la Isla Reunión en el océano Índico. En Brasil es considerada como la principal plaga del café (12,27,32), por su ocurrencia generalizada y a los perjuicios económicos causados (12,26), los cuales pueden llegar hasta un 50% de pérdidas en producción (20), debido a que todas las variedades de Coffea arabica cultivadas en Brasil son susceptibles a este insecto (16). Existen reportes de poblaciones de este insecto resistentes a insecticidas que son usados para controlarlo; Alves et al. (2) encontraron resistencia de L. coffeella a organofosforados, especialmente clorpirifos, con una frecuencia de insectos resistentes <12%. ...
... La biología de este insecto ha sido estudiada por diversos autores (29, 32, 33, 35), quienes determinaron que el desarrollo del insecto de huevo a adulto puede variar de acuerdo a la variedad de café en la que se desarrolla, así como a las condiciones de temperatura, humedad relativa y precipitación pluviométrica. Los resultados con relación a la duración del ciclo de huevo a adulto reportados en la literatura, pueden variar entre 19 y 87 días, encontrándose como un rango favorable de temperatura para el desarrollo del insecto de 22 a 28°C (12,13,26,27,32). Trabajos adelantados en Brasil por Parra (26) y Magalhães et al. (19), evaluando diferentes genotipos del género Coffea, determinaron que la biología, sobrevivencia y fecundidad del insecto se ve afectada por el genotipo de Coffea en que se desarrolla y se atribuye a las diferencias de alcaloides y fenoles presentes en las hojas. ...
... El desempeño de un gasificador es afectado principalmente por el tipo y condiciones de la biomasa (contenido de humedad, tamaño y densidad), flujo de la biomasa, agente oxidante utilizado y flujo y relación de equivalencia (kg de aire/kg de biomasa suministrado y kg de aire/kg de biomasa estequiométrico) (10,12,14,27). ...
Article
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BIOLOGICAL ASPECTS OF Leucoptera coffeella (Guérin-Mèneville, 1842) (Lepidoptera: Lyonetiidae) IN LABORATORY CONDITIONS IN Coffea arabica VAR. IAC OBATA 4739 Leucoptera coffeella (Guérin-Mèneville, 1842) (Lepidoptera: Lyonetiidae) is a key pest of coffee crops in Brazil and potential problem in Colombia under climatic variability scenarios. The objective of this study was to determine some aspects of the biology, reproduction and developmental conditions of this pest in laboratory: temperature 25±2C°, relative humidity RH: 70±10%, photoperiod of 14:10 (L:D) using coffee leaves var. IAC Obatã 4739, expanding variety in Brazil. The insect life cycle from egg to adult took 20,88 ± 0,89 days, the survival: from egg to adult was 90 ± 8,7 %. Adult females had a pre-oviposition period of 3.4 ± 0.2 days and an average fertility of 60.3 ± 3.8 eggs.
... Biomass beside other renewable energy sources (like solar and wind) has been recognized as an ideal candidate for decentralized energy systems [1]. India being rich in biomass production, it is ideally suited for decentralized power generation purpose [2]. ...
... One of the most attractive applications of producer gas fuel besides heating, water pumping, brick kiln and flour mill is its use in internal combustion engines for power generation. For air gasification process, the gas quality or composition including tar (as a result of incomplete oxidation of volatiles) and quantity varies widely depending on the gasifier configuration, chemical composition of the feedstock, its moisture, ash content, its size, density, equivalence ratio, reaction temperature profile and turn down of power level [1,13,14]. The outcomes of the engine research fueled with producer gas, syngas, hydrogen, and methane are discussed as follows. ...
Article
Full-text available
This article addresses the effect of combustible components (hydrogen and methane) of a producer gas fuel on in-cylinder combustion, performance, and emissions of a modified spark ignition engine. Owing to the fluctuating tendency of an onsite gasifier produced producer gas composition, a dynamic behavior in engine combustion and performance was expected. Thus, the present study was motivated to investigate the magnitude of the engine response variables against the known fluctuating producer gas composition trend. Experiments were conducted using bottled fueled producer gas on 359 cm³ engine capacity at a compression ratio of 11:1 and 1500 rpm. Further, the engine was operated under naturally aspirated mode and close to stoichiometry. The analysis based on acquired in-cylinder data revealed that, the fractions of hydrogen and methane have a profound effect on combustion duration and specific fuel consumption. Further, the producer gas blends, leading to reduction in fuel gas consumption were identified. On emission front, carbon-monoxide and nitric oxide pollutants were predominant but within prescribed central pollution control board norms of India, especially at full load engine condition and hydrogen enriched blend respectively.
... Roy et al. [7] simulated a biomass downdraft gasifier by using thermodynamic equilibrium approach for the pyro-oxidation and a chemical kinetic model for the reduction zone. Sharma [39] extended a formulation to numerically simulate the performance of the downdraft biomass gasifier. Biomass drying and partial oxidation zones were formulated by thermal equilibrium approach, while pyrolysis was modelled by single pseudo-first order reaction using an empirical model and char reduction zone was investigated by kinetic scheme. ...
... Early studies of gasifier modelling [33e36, 39,55,56] mostly applied simple single-step global reaction schemes to simulate pyrolysis chemical phenomena, which rely on practical correlations to determine the exact gas and tar substrates and concentrations. Although these single-step pyrolysis reaction schemes are easy to implement in codes, they were likely to cause drawbacks particularly in successive models [44]. ...
Article
Syngas production from biomass resources suggest considerable privileges to attain energy sustainability in future. Design and control strategies are essential to extend the technology of biomass gasifiers, which require reliable model developments. The overarching contribution of this study is to develop and evaluate a three-stage biomass gasifier model. The model consists of three successive sub-models for drying and pyrolysis, partial oxidation and char reduction reactors. The pyrolysis of raw material is simulated based on the ligno-cellulosic structure of the biomass by adopting comprehensive kinetic rate modelling approach. The partial oxidation sub-model is built by axis-symmetric 2D transport equations including detailed chemical scheme. Char reduction sub-model is extended based on axis-symmetric 2D DPM model accompanied by appropriate chemical kinetic scheme considering heterogeneous and homogeneous reactions. Accuracy of each sub-model is separately verified by comparison with available numerical and experimental data. Moreover, the correctness and predictability of the complete gasifier model is evaluated using two experimental reports. For both cases, investigations demonstrate high resolution agreement between the results of the developed model and available experimental measurements both thermally and chemically. Furthermore, a parametric analysis is conducted to investigate the gasifier performance against the variations of the main system operating parameters including the type of the feeding biomass and its moisture content, equivalence ratio and air initial temperature. Based on the results, higher volatiles mass fractions and lower char mass fraction have been produced from pyrolyzing of hardwood in comparison with beech wood. Also, Results reveal that with increase of the moisture content from 15% to 35%, syngas LHV and cold gas efficiency reduce by 1.9559 MJ. kg⁻¹ and 25.78% respectively, while H2 mole fraction at the gasifier outlet rises by 0.90%. On the contrary, growth of equivalence ratio from 2 to 10 leads to the drastic increase of syngas LHV by 5.6404 MJ. kg⁻¹, however, cold gas efficiency peaks to 82.75% at the equivalence ratio of 4. Besides, varying the inlet air temperature over a range of 500 K–1300 K causes 0.6938 MJ. kg⁻¹ growth of syngas LHV as well as 9.43% rise of cold gas efficiency.
... Se hace indispensable, por tanto, el desarrollo creciente de las fuentes alternativas de energía. Una de las fuentes mayoritarias está constituida por la biomasa, de la que se dispone en abundancia y tiene mucho menor impacto al medio ambiente que los combustibles fósiles [1]. La operación racional de las instalaciones de gasificación de biomasa contribuye también a la reducción de las emisiones contaminantes, costos de generación, etc. [2,3]. ...
... En general, el proceso de gasificación depende de varios factores, entre los que se destacan la temperatura de pirólisis, parámetro que determina el rompimiento de la molécula de la biomasa experimental gracias a la reacción de reducción que se produce por la cantidad de calor existente en el reactor, además de la presión en el mismo. En el caso de estudio de los gasificadores tipo downdraft, la calidad del gas que produce la instalación depende no solo de las características del flujo de gas, del agente gasificante utilizado, del tipo de biomasa y del diseño del reactor, sino también de los parámetros de operación [1][2][3][4]. El análisis real del proceso de gasificación, por su complejidad y diversidad en procesos que ocurren en tiempos pequeños, tiene muchas dificultades. ...
Article
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Licencia de uso y distribución CreativeCommons Reconocimiento-No Comercial 4.0 Internacional. RESUMEN/ABSTRACT En el trabajo se presentan resultados investigativos obtenidos por los autores en el modelado de indicadores de desempeño de la operación de instalaciones de gasificación de la biomasa con ayuda de redes neuronales artificiales, a partir de la clasificación de la información derivada del análisis sistémico de la operación de estas instalaciones. Se realiza el estudio bibliográfico de los trabajos de investigaciones previos, vinculados al modelado matemático de estas instalaciones por las diferentes técnicas reflejada en la literatura especializada. Se realiza un plan experimental 3 N con tres réplicas, a partir del cual se elaboran, utilizando las técnicas de las redes neuronales, cuatro modelos correspondientes a respectivos indicadores de desempeño, con satisfactorios resultados de su evaluación a partir de los coeficientes de regresión y errores estándar utilizando como biomasa el Eichhornia Crassipes. Se describe la instalación experimental y el sistema de adquisición de datos desarrollados. Palabras clave: gasificación de biomasa; fuentes de energía renovable; redes neuronales artificiales; operación de procesos. The research results are presented by the authors in the modeling of performance indicators of the operation of biomass gasification facilities through the use of artificial neural networks, starting from the classification of the information derived from the systemic analysis of the operation of these facilities. A bibliographical study of previous research, related to mathematical modeling of these facilities through the different techniques specified on the literature was developed. A 3 N experimental plan with 3 replicas is made to generate four models according to their own performance indicators using neural networks, with satisfactory results of their evaluation and based on regression coefficients and standard errors using Eichhornia Crassipes as biomass. The experimental installation and the developed data acquisition systems are described. INTRODUCCIÓN Como consecuencia del creciente consumo de combustibles, se observa el incremento en los últimos años de los fenómenos asociados a la crisis energética y al calentamiento global. Se hace indispensable, por tanto, el desarrollo creciente de las fuentes alternativas de energía. Una de las fuentes mayoritarias está constituida por la biomasa, de la que se dispone en abundancia y tiene mucho menor impacto al medio ambiente que los combustibles fósiles [1]. La operación racional de las instalaciones de gasificación de biomasa contribuye también a la reducción de las emisiones contaminantes, costos de generación, etc. [2,3]. En general, el proceso de gasificación depende de varios factores, entre los que se destacan la temperatura de pirólisis, parámetro que determina el rompimiento de la molécula de la biomasa experimental gracias a la reacción de reducción que se produce por la cantidad de calor existente en el reactor, además de la presión en el mismo.
... Furthermore, low ash fusion temperature also leads to blockage of the fuel flow which reduces the heat transfer potential and gas quality [125]. In addition, the probable volatization of gas phase compounds of the toxic inorganic elements like heavy metals at high temperatures (750-1100 • C) results in deposition [142][143][144][145]. ...
... Furthermore, low ash fusion temperature also leads to blockage of the fuel flow which reduces the heat transfer potential and gas quality [125]. In addition, the probable volatization of gas phase compounds of the toxic inorganic elements like heavy metals at high temperatures (750-1100 °C) results in deposition [143][144][145][146]. ...
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The increasing volume of sewage sludge from wastewater treatment facilities is becoming a prominent concern globally. The disposal of this sludge is particularly challenging and poses severe environmental hazards due to the high content of organic, toxic and heavy metal pollutants among its constituents. This study presents a simple review of four sewage to energy recovery routes (anaerobic digestion, combustion, pyrolysis and gasification) with emphasis on recent developments in research, as well as benefits and limitations of the technology for ensuring cost and environmentally viable sewage to energy pathway. This study focusses on the review of various commercially viable sludge conversion processes and technologies used for energy recovery from sewage sludge. This was done via in-depth process descriptions gathered from literatures and simplified schematic depiction of such energy recovery processes when utilised for sludge. Specifically, the impact of fuel properties and its effect on the recovery process were discussed to indicate the current challenges and recent scientific research undertaken to resolve these challenges and improve the operational, environmental and cost competitiveness of these technologies.
... Performance produced gas composition of a gasification process is dependent upon the feedstock characteristics, the reactor design and the operating parameters [13]. Feedstock characteristics that have been found to have major influence on the gasification process are moisture content, volatile matter, ash content, char and thermal conductivity [13]. ...
... Performance produced gas composition of a gasification process is dependent upon the feedstock characteristics, the reactor design and the operating parameters [13]. Feedstock characteristics that have been found to have major influence on the gasification process are moisture content, volatile matter, ash content, char and thermal conductivity [13]. Sewage as a fuel is characterized by completely different properties in comparison to conventional biomass. ...
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This paper presents an investigation of sewage sludge gasification in a fixed bed gasifier. Experiments were conducted on a laboratory scale fixed bed gasifier. In the experiments, two types of dried sewage sludge were tested and their properties were analysed. Parameters such as air ratio λ = 0.12 to 0.27, gasification agent temperature t = 50 to 250 °C and gasification agent composition ( z o 2 > = 0.21 and z o 2 > 0.21) were found to influence on temperature distribution, syngas Lower Heating Value (LHV) and syngas composition. The results indicate that the syngas LHV was found to decrease with increased air ratio for all analyzed cases: cold and preheated air and cold enriched air. The increase in the percentage of the main combustible components was accompanied by a decrease in the concentration of carbon dioxide. Increasing oxygen concentration increased the temperature, which tended to favor the formation of smaller molecules in the gas mixture. Thus, the enriched air medium produced a gas with a higher LHV. In contrast to conventional gasification, gasification process with gasification agent preheating causes that the flux of heat necessary to support endothermic gasification reactions is producing more effective. Air preheating causes increases hydrogen and carbon monoxide production.
... As the feedstock particles are heated during the drying process, moisture is drawn out of them. The pyrolysis phenomenon decomposes the biomass feedstock into char, volatiles, and tar after drying and raising the temperature [9,10]. These pyrolysis products reach the oxidation zone where charcoal with volatiles reacts with a restricted oxidizing agent which leads to an increase in the temperature as this reaction is exothermic. ...
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Biomass gasification is one of the prominent technologies for thermal applications, electricity generation through engines. The present investigation was carried out to obtain behavior of multi-flow gasifier by using locally available wood biomass chips (i.e., Acacia Nilotica & Eucalyptus biomass). Experiments were conducted to examine the variation of gas composition, LHV, cold gasification efficiency, equivalence ratio at different flow rates, and pressure drop with the time in complete operation of gasifier. Result shows that producer gas obtained from this gasifier has maximum lower heating value of 4.39 MJ/kg with hydrogen gas (13.61% vol/vol) and carbon monoxide (15.61% vol/vol). The composition of CH4 in producer gas was less than 2%. The maximum cold gas efficiency of 72.2% was obtained at optimal equivalence ratio of 0.309 with gas flow rate of 5 g s⁻¹ with moisture content of 7.51%. These locally available wood can be appropriate feedstock for gasifiers. The clean and cooled gas can be utilized in internal combustion engines or turbines for clean power production.
... The current study concerns to couple the gasifier model with a pyrolysis sub-model which be able to determine the CH 4 , H 2 , CO, CO 2 , H 2 O, tar and char concentrations at the pyrolysis outlet for a wide range of lingo-cellulosic wastes. Thus, instead of simple single-step global reaction schemes [18,19,24,27,30,38,39], the pyrolysis sub-model is developed based on the multi-step kinetic scheme of Ranzi et al. [40]. ...
Article
Biomass gasification suggests several advantages toward clean environment and energy sustainability. Multi-stage gasifires enhance the process efficiency and syngas quality. Thus, multi-stage model developments are essential to take into account separate chemical schemes for successive pyrolysis and partial oxidation reactors. The current study is contributed to develop and evaluate a conceptual three-stage biomass gasifier model. The model is built by integrating three successive sub-models for drying and pyrolysis, partial oxidation and char reduction reactors. Pyrolysis sub-model is based on kinetic rate modelling with considering biomass lingo-cellulosic structure. Partial oxidation sub-model is developed by applying axis-symmetric 2D transport equations accompanied by appropriate chemical scheme. Char reduction sub-model is extended based on axis-symmetric 2D DPM model as well as appropriate chemical kinetic scheme. Accuracy of each sub-model and also the whole three-stage gasifier model are separately verified against available experimental data. Verification analysis demonstrates high resolution agreement between the results of the developed model and available experimental data. Simulations ascertain that gasification of 24.8 kg. hr⁻¹ hardwood with about 26.5% moisture content in presence of 7 kg. hr⁻¹ steam and 25 kg. hr⁻¹ air has produced syngas with the composition of 1.92% CH4, 34.02% H2, 16.77% CO, 14.63% CO2 and 32.66% N2, outlet tar concentration of 2.3439 gr. N m⁻³ and grate char particles concentration of 0.0397 kg. m⁻³.
... From the reference of coal gasification process developed in 18-19 centuries, biomass gasification presents nowadays as a versatile and promising way to utilize various kinds of biomass sources (e.g., forest, municipal and agricultural wastes) (Susastriawan et al. 2017;Shahbaz et al. 2017;Sansaniwal et al. 2017;Lythcke-Jørgensen et al. 2017;Ismail and El-Salam 2017;Heidenreich and Foscolo 2015;Pereira et al.2012). If found technically and financially feasible, biomass gasification has the potential to increase the deployment and adoption of renewables, which will augment the sustainable production of chemicals and syngas utilized in internal combustion engines for power generation (Wang et al.2016;Chaves et al.2016;Ruiz et al.2013;Yoon et al.2012;Martínez et al.2012;Son et al. 2011;Sharma 2011;Bridgwater 1995;Rajvanshi and Joshi 1989). In the development of technology, it is a standard procedure to attempt a successful and optimized operation of miniaturized systems before commercial-scale development; biomass and/or waste gasification is no exception. ...
Article
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Disaster-hit and/or un-electrified remote areas usually have electricity accessibility issues and an abundance of plant-derived debris and wood from destroyed wooden structures; this can be potentially addressed by employing a decentralized ultra-small biomass-fed gasification power generating system. This paper presents an assessment of the technical viability of an ultra-small gasification system that utilizes densified carbonized wood pellets/briquettes. The setup was run continuously for 100 h. A variety of biomass was densified and carbonized by harnessing fugitive heat sources before charging into the reactor. Carbonized briquettes and furnished blends exhibited inferior gasification performance compared to the carbonized pellets. In the absence of tar blockage problems, steady-state conditions were achieved when pre-treated feedstock was used. Under steady-state conditions for carbonized pellets gasification operated at an equivalence ratio of 0.32, cold gas efficiency and carbon conversion achieved 49.2% and 70.5%, respectively. Overall efficiency and maximum power output of 20.3% and 21 kW were realised, respectively. It was found that the system could keep stable while the low heating valve of syngas was over 4 MJ/m ³ on condition that avoiding tar blocking issues. The results indicate that the proposed compact ultra-small power generation system is a technically feasible approach to remedy power shortage challenge. In addition, process simulation considering carbonized wood gasification combined power generation was formulated to produce syngas and electricity. Woody pellets with the flow rate of 20 kg/h could generate a 15.18 kW power at the air flow rate of 40 Nm ³ /h, which is in a good agreement with 15 kW in the 100 h operation. It is indicated that the gasification combined power generation cycle simulated by Aspen simulator could achieve reliable data to assist the complicated experiment operation.
... [4][5][6][7][8][9][10] If found technically and financially feasible, biomass gasification has the potential to increase the deployment and adoption of renewables to augment the sustainable production of chemicals and syngas for power generation through utilization in internal combustion engines. [11][12][13][14][15][16][17][18][19] In the development of technology, it is a standard procedure to attempt a successful and optimized operation of miniaturized systems before commercial-scale development; biomass and or waste gasification is no exception. The demand for cheap, agile biomass power generation systems is high, especially in disaster-prone areas like coastal Japan and areas with an abundance of biomass but no accessibility to the national electricity grid. ...
Preprint
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Disaster-hit and/or un-electrified remote areas usually have electricity accessibility issues and an abundance of plant-derived debris and wood from destroyed wooden structures; this can be potentially addressed by employing a decentralized ultra-small biomass-fed gasification power generating system. This paper presents an assessment of the technical viability of an ultra-small gasification system that utilizes densified carbonized wood pellets/briquettes. The setup was run continuously for 100 hours. A variety of biomass was densified and carbonized by harnessing fugitive heat sources before charging into the reactor. Carbonized briquettes and furnished blends exhibited inferior gasification performance compared to the carbonized pellets. In the absence of tar blockage problems, steady-state conditions were achieved when pre-treated feedstock was used. Under steady-state conditions for carbonized pellets gasification operated at an equivalence ratio of 32%, cold gas efficiency, and carbon conversion of 49.2%, and 70.5% was achieved, respectively. Overall efficiency and maximum power output of 20.3% and 21 kW were realised, respectively. The results indicate that the proposed compact ultra-small power generation system is a technically feasible approach to remedy power shortage challenge.
... PG is used in the IC engine as a primary fuel in the case of a spark-ignition engine (SI). In CI engines, it is used in dual fuel mode where diesel/biodiesel is used as pilot fuel, and producer gas is used as the main fuel (Sharma 2011). In dual-fuel type engines, the PG is mixed with air and directly introduced to the combustion chamber and diesel/biodiesel is injected through the fuel injector as pilot fuel (Kumar and Sharma 2017). ...
Article
The present work reports the development of a mathematical model to establish a correlation between controllable engine input parameters and their dependent responses over a varied range of engine loadings. Brake thermal efficiency (BTE), peak combustion pressure, and exhaust gas temperature (EGT) are chosen as a response while engine load, pilot fuel injection timing (FIT), and pilot fuel injection pressure (FIP) are taken as controllable input. The response surface methodology (RSM) has been used for the model development based on multilinear regression analysis and the design of experiments techniques. The experimental data for model development was collected through lab-based experiments carried out using diesel engines in dual-fuel mode. The dual-fuel engine was powered with producer gas as the main fuel and waste cooking oil biodiesel as pilot fuel. The best possible combination of input parameters optimized by RSM helps in the improved and stable operation of the dual-fuel engine. Furthermore, the developed model can predict the output responses very close to experimental results. The model robustness is verified with high values of correlation coefficients R² for all three response variables.
... Such operation in fumigation form ensures energy sustainability with ambient harmony. Researchers have performed experimental investigations on biomass gasification system to derive good quality producer gas [1,2,[4][5][6][7]. Numerous works were documented on dual fuel fumigation based on producer gas and diesel as guiding fuel [3,4,[8][9][10][11]. ...
... Biomass is a combination of lignin, hemicelluloses, cellulose, and other organics, which poralose or degrade at a different rate [11]. Residue biomass like agricultural waste and forest residue can be used for the energy needs by the means of biological or thermochemical processes [12]. Biofuels in form of liquid especially bioethanol has one of the possibilities for the substitution of transport fuels and electrical power generation. ...
Article
ss Attention towards the use of biomass for Power Generation has increased intensely from the past few years because of the awareness of global warming and a bad effect on the environment due to the fossil fuels combustion. This paper addresses the challenges for power production using paddy straw faced during the procurement and its storage. This paper opted an investigative study using the open-ended approach of grounded theory, including sample collection and experimenting. It has been observed that the various challenges are farmer awareness, transportation cost, storage cost, degradation due to storage and pre-feeding costs. The results have shown that there is 20.49% decrease in Calorific Value due to degradation of paddy straw at storage. The cost of generation in the month of procurement (Oct) is 0.02304$/kWh and it has been evident that increase is exponential in nature and stepped to 25. 76% in one year which is quite effective and make this study fit for its purpose.
... Gasification in a fixed bed has been a subject of extensive research [31,36,37,[52][53][54][55][56][57][58]. However, there is still a knowledge gap in terms of influence of torrefaction on the gasification of thermally thick particles. ...
Article
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Gasification of biomass in fixed bed gasifiers is a well-known technology, with its origins dating back to the beginning of 20th century. It is a technology with good prospects, in terms of small scale, decentralized power co-generation. However, the understanding of the process is still not fully developed. Therefore, assessment of the changes in the design of a gasifier is typically performed with extensive prototyping stage, thus introducing significant cost. This study presents experimental results of gasification of a single pellet and bed of particles of raw and torrefied wood. The procedure can be used for obtaining design parameters of a fixed bed gasifier. Results of two suits of experiments, namely pyrolysis and CO2 gasification are presented. Moreover, results of pyrolysis of pellets are compared against a numerical model, developed for thermally thick particles. Pyrolysis time, predicted by model, was in good agreement with experimental results, despite some differences in the time when half of the initial mass was converted. Conversion times for CO2 gasification were much longer, despite higher temperature of the process, indicating importance of the reduction reactions. Overall, the obtained results could be helpful in developing a complete model of gasification of thermally thick particles in a fixed bed.
... Materials with both a low bulk density (< 180 kg/m 3 ) and a high angle of repose (> 52˚) had a high average pressure drop across the reactor (air dried WP and C&D, pine control), as seen in Fig. 3a. The pressure drop across the reactor has been previously shown to be affected by feedstock bulk properties such as porosity, and bulk density [33]. Poor bulk properties also result in a "slugging" behaviour of the material through the gasifier due to the formation of bridges/channels within the pyrolysis zone and subsequent collapse of solid bridges naturally or due to grate shaking, which manifests as a large standard deviation of pressure drop (Fig. 3a). ...
Article
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Small-scale biomass gasification systems integrated with internal combustion engines can be a solution to the dual challenges of reducing greenhouse gas emissions from electricity production and reducing waste sent to landfills; however, these systems are typically designed for high-value, virgin wood chip feedstocks. This investigation aims to improve the feasibility of this technology by exploring the use of landfill diverted wood wastes (construction and demolition waste, used pallets and oriented strand board) in place of costly wood chips for the production of bioenergy in a pilot scale gasifier combined with an internal combustion engine generator operating at 10 kWe. The effect of feedstock bulk properties on gasifier operational stability and process parameters, including magnitude and variability of temperature and pressure drop, are investigated. Low bulk density (< 200 kg/m³) and high angle of repose (> 55°) increased system instability through the formation and collapse of bridges and channels in the gasifier. Tar and particulate matter in the producer gas are quantified, as well as removal efficiencies of the gas clean-up for different feedstocks. Tar concentration in the syngas was in the range of 1.2 to 5.2 g/m³ downstream of gas clean-up, and was found to increase with system instability parameters and feedstock moisture. Finally, over the range of feedstocks examined in this study, a novel empirical correlation was developed to describe tar production from the gasifier as a function of feedstock bulk properties. The relationship between feedstock bulk properties and tar production is a unique finding and can enable to development of reliable waste-to-energy gasification systems. Graphic Abstract
... Along with the increase of performance, it also enhances the pressure drop thus increasing the pumping power [5]. ...
Conference Paper
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In the present energy crisis scenario, focus of the scientist struggle is to produce sustainable, renewable and continuous form of energy. In this quest, the response of energy production technique using gasification has reproduced positive results. In this project we have focused to substitute diesel consumption using producer gas in a dual fuel power generator. It involves the installation of one 14 kWe biomass gasifier system with dual fuel engine and generator in the lIT (BHU) campus. The performance of the system is studied under actual varying load by connecting it to the various loads and using woody biomass. Then, the performance data of the system are obtained using a combination of locally available fuels like rice husk, nut shell, cotton stock and eupatorium. Based on the data obtained, modifications required to improve the performance will be suggested. The performance study of the modified system may be taken up as a future work. Based on few simple calculations it can be shown that, the cost of power generation using a woody biomass gaisfier system is around Rs. 3.5 per unit. This is much cheaper when compared to the cost power generation using diesel. However, the technology needs refinement in the areas of fuel quality, retrofitting performance data for locally available fuels etc. The proposed project is expected to yield fruitful results in this area. This will in turn make the technology and technical expertise available for commercial applications in this area.
... Nevertheless, it is an important exercise to examine the range of results that have been obtained to identify the bounds of stable operation of CHP systems. Therefore, a thorough review of the literature was conducted to examine the effect of feedstock characteristics (moisture content and particle size) on the performance (LHV, η CG , η e , and η gen ) of the gasifiers using wood chips, as shown in Fig. 5 [13,15,17,19,23,[25][26][27][28][29]34]. Both gasifiers that evolved producer gas that was flared or integrated with an ICE for bioenergy production were included in this analysis as comprehensive data sets that reported all performance metrics with information on feedstock characteristics were scarce. ...
Article
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Small-scale downdraft biomass gasification is a promising technology for off-grid combined heat and power generation utilizing Canada’s vast biomass resources. As small-scale gasifiers are currently emerging into the Canadian market, the current study investigates the required feedstock characteristics for stable operation using Canadian softwood, along with the quality of the biochar produced as a byproduct. It was found that reducing feedstock moisture from 20 to 9% increased overall system efficiency from 8.2 to 12%. Equilibrium simulations were utilized to evaluate the deviation from ideal conversion when using feedstock outside the gasifier feedstock specifications. These showed the gasifier was operating close to equilibrium, with the lower heating value of the actual producer gas deviating by an average of 9% from simulated results. This study provides a novel methodology for the quantification of reliability and efficiency of these systems which can be used to evaluate the economic benefit of these systems in Canada.
... En el presente artículo se enfrenta el problema de la operación de instalaciones de termo gasificación tipo downdraftsobre una base sistémica. Este tema se había enfrentado, hasta el presente, tan solo desde el punto de vista de la búsqueda de relaciones entre variables de supuesta influencia, careciéndose de un enfoque integral [1]. La operación de los procesos requiere de la definición de la estructura de modelos y de su identificación experimental inicial y su posterior rectificación adaptiva en el curso de la explotación de estas instalaciones. ...
Presentation
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RESUMEN El presente trabajo aborda el modelado matemático para la operación de instalaciones de gasificación tipo downdraft, funcionando con los tipos de biomasa predominantes en la región andina del Ecuador, tema de gran actualidad dada la necesidad de reducir el impacto ambiental derivado del uso de combustibles fósiles en la generación de energía. Se realizael análisis externo e interno de la tarea de toma de decisiones asociada, del que se deriva el modelo matemático conceptual de la operación. Para la identificación de las relaciones que forman parte del modelo se utilizan técnicas de regresión no-lineal y de redes neuronales artificiales a partir de los datos obtenidos como resultado de la implementación de planes experimentales concebidos para identificar el modelo conceptual. Se brindan los esquemas de solución de los modelos de optimización no-lineal estocástica y los procedimientos utilizados para la elaboración de reglas de conducta asociados a la operación de estas instalaciones. ABSTRACT Present work faces the mathematical modeling for the operation ofdowndraft type thermochemical gasification installations, working with the predominant types of biomass characteristic to the Andean region of Ecuador, topic of great importance, given the necessity to reduce the environmental impact derived from the use of fossil fuels in the energy generation. The external and internal analysis of the decisionsmaking task associated are carried out, from which the conceptual mathematical model of the operation is derived. For the identification of the relationships that are component parts of the model non-lineal regression technics and neural artificial nets are used, starting from the data obtained as a result of the implementation of experimental plans conceived to identify the conceptual model. The solution outline of the stochastic no-lineal optimization model and the procedures for the elaboration of behavior rules associated used to the operation of these facilities are offered.
... The composition of syngas depends on the properties of feedstock and the operating temperatures. 32 The syngas thus produced is very important for industries as it can be used for the production of heat, electricity, fertilizers, chemicals, and liquid fuels. 33 The process of biomass gasification involves four important stages: drying of biomass, pyrolysis, oxidation, and reduction. ...
Article
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It is important for researchers to look at alternative fuels to reduce dependence on fossil fuels as a primary source of energy, to protect the environment, and to reduce greenhouse‐gas emissions. An alternative fuel has to be environment friendly and economically viable, both in terms of production and suitability for the modern world. Fuel derived from biomass has long been viewed as a potential replacement. First‐generation biomass‐derived fuels such as bioethanol and biodiesel have already been competing with conventional fuels, assisted by legislation. This review paper assesses the feasibility of adapting and incorporating second‐generation advanced biofuel production technology for the thermochemical conversion of biomass to produce alternative fuels. The conversion technologies considered here are pyrolysis and gasification, and their potential has been examined using techno‐economic assessment (TEA). A brief overview of different business models that can be incorporated during TEA has also been discussed. Techno‐economic assessment data help in determining costs of technologies if they are employed on a commercial scale, especially in terms of per unit cost of product. The review has compiled the technical and economic data available for assessing the types and combination of processes that can assist competitiveness in the existing market. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.
... En la presente investigación el problema de la operación de instalaciones de termo-gasificación en instalaciones tipo downdraft se enfrenta sobre una base sistémica, Este tema, hasta el presente se ha enfrentado tan solo desde el punto de vista de la búsqueda de relaciones entre variables de supuesta influencia, careciéndose de un enfoque integral [1]. La operación de los procesos requiere de la definición de la estructura de modelos y de su identificación experimental inicial y su posterior rectificación adaptiva en el curso de la explotación de estas instalaciones. ...
Article
Optimal operation of energetic installations must considerably influence on its efficiency. By this, the objective of the present paper consists in the definition of the required models structure for the operation of downdraft gasifiers and its identification based on systemic analysis, it identification and the determination of the better adjustment type of model. For the models identification an experimental installation was constructed using, between other biomasses, firewood. Starting from an 3N experimental plan, with three replicas, needed models were identified helped by artificial neural networks and regression techniques. The best results were obtained using neural network, being therefore the most advisable in the preliminary stage of the process of the adaptive construction of operation models of the studied process.
... El gas de salida del proceso de gasificación tipo downdraft depende de la cantidad del carbono que se produce durante la pirólisis y del agente gasificante utilizado en el proceso, el que depende de la temperatura de pirólisis, la que determina el rompimiento de la molécula de la biomasa gracias a la reacción de reducción que se produce por la cantidad de calor existente en el reactor y de la presión en el mismo. La calidad del gas que produce la instalación depende no solo del tipo de biomasa y del diseño del reactor, sino también de los parámetros de operación (Azzone, 2013;Sekhar y et al., 2013;Sharma, 2011). ...
Article
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p>En el trabajo se presentan resultados investigativos obtenidos por los autores en el modelado de indicadores de desempeño de la operación de instalaciones de gasificación de la biomasa con ayuda de redes neuronales artificiales, a partir de la clasificación de la información derivada del análisis sistémico de su operación. Se realizó el estudio bibliográfico de los trabajos de investigaciones previos relacionados. A partir de un plan experimental 3N con tres réplicas se elaboran, utilizando las técnicas de las redes neuronales, cuatro modelos correspondientes a respectivos indicadores de desempeño, los que se comparan con los obtenidos por modelos de regresión no lineal. Como biomasa se utiliza el Oryza sativa.</p
... En la presente investigación el problema de la operación de instalaciones de termo-gasificación en instalaciones tipo downdraft se enfrenta sobre una base sistémica, Este tema, hasta el presente se ha enfrentado tan solo desde el punto de vista de la búsqueda de relaciones entre variables de supuesta influencia, careciéndose de un enfoque integral [1]. La operación de los procesos requiere de la definición de la estructura de modelos y de su identificación experimental inicial y su posterior rectificación adaptiva en el curso de la explotación de estas instalaciones. ...
... There are also two operational parameters bed temperature and pressure across the reactor which afects the process of gasiication as well as ultimate heating values and the syngas composition. The pressure gradient, which is monitored using pressure sensors positioned at diferent levels across the reactor, is a function of system coniguration, geometry, feedstock porosity, permeability and physical properties of the feedstock [14]. ...
... The coded values for operating variables (A, B and C) were set at three levels: −1 (low), 0 (medium) and 1 (high). The selection of operating variables along with their respective levels were based on the previous research on the algal gasification process [7,17,35,36]. According to the design, fifteen tests were performed. ...
Article
This study presents the optimization of algal biomass catalytic gasification for hydrogen-rich gas production. Three operating parameters under varying conditions of temperature (700–900 °C), catalyst loading (5–20 wt%) and reaction time (15–40 min) were optimized. The central composite design (CCD) was used to perform optimization and to investigate the influence of operating parameters on response variables (fractions of H2, CO, CO2 and CH4). The results indicated the temperature and catalyst loading as the most significant reaction parameters influencing H2 production and reducing the tar produced during the gasification process. The highest H2 fraction of 48.95 mol% (18.77 mol kg-biomass−1) was obtained at an optimum condition at 851 °C with catalyst loading of 16.4 wt% and reaction time of 28.8 min. The high R2 values of 0.98, 0.97, 0.95, and 0.90 corresponding to the response variables (H2, CO, CO2 and CH4) showed paramount estimation of model
... The end-products of WAS gasification depend on its properties (such as moisture, VM, ash, and thermal conductivity) and experimental conditions (such as temperature, HR, and feeding ratio) [79]. Table 4 shows experimental conditions and results corresponding to sludge air gasification [72,80,81], steam sludge gasification [72,81,82] and supercritical sludge gasification [83] reported in literature. ...
Article
Sludge or waste activated sludge (WAS) generated from wastewater treatment plants may be considered a nuisance. It is a key source for secondary environmental contamination on account of the presence of diverse pollutants (polycyclic aromatic hydrocarbons, dioxins, furans, heavy metals, etc.). Innovative and cost-effective sludge treatment pathways are a prerequisite for the safe and environment-friendly disposal of WAS. This article delivers an assessment of the leading disposal (volume reduction) and energy recovery routes such as anaerobic digestion, incineration, pyrolysis, gasification and enhanced digestion using microbial fuel cell along with their comparative evaluation, to measure their suitability for different sludge compositions and resources availability. Furthermore, the authors shed light on the bio-refinery and resource recovery approaches to extract value added products and nutrients from WAS, and control options for metal elements and micro-pollutants in sewage sludge.
... The end-products of WAS gasification depend on its properties (such as moisture, VM, ash, and thermal conductivity) and experimental conditions (such as temperature, HR, and feeding ratio) [79]. Table 4 shows experimental conditions and results corresponding to sludge air gasification [72,80,81], steam sludge gasification [72,81,82] and supercritical sludge gasification [83] reported in literature. ...
Article
Full-text available
Sludge or waste activated sludge (WAS) generated from wastewater treatment plants may be considered a nuisance. It is a key source for secondary environmental contamination on account of the presence of diverse pollutants (polycyclic aromatic hydrocarbons, dioxins, furans, heavy metals, etc.). Innovative and cost-effective sludge treatment pathways are a prerequisite for the safe and environment-friendly disposal of WAS. This article delivers an assessment of the leading disposal (volume reduction) and energy recovery routes such as anaerobic digestion, incineration, pyrolysis, gasification and enhanced digestion using microbial fuel cell along with their comparative evaluation, to measure their suitability for different sludge compositions and resources availability. Furthermore, the authors shed light on the bio-refinery and resource recovery approaches to extract value added products and nutrients from WAS, and control options for metal elements and micro-pollutants in sewage sludge. Recovery of enzymes, bio-plastics, bio-pesticides, proteins and phosphorus are discussed as a means to visualize sludge as a potential opportunity instead of a nuisance.
... Large scale gasifiers are still at pilot stage [40][41]. Numerous works undertaken in the field of gasification have probed into operational problems such as tar removal, use of by-products of gasification and evaluation of the internal combustion engines on producer gas to help in developing gasification technology in India [42]. Biomass pyrolysis for production of pyrolysis oil for transportation fuel is still evolving. ...
Chapter
Rising energy security concerns associated with the depleting fossil fuel reserves have triggered renewed interests in the utilisation of biomass for energy. Highly vulnerable to the energy instability, developing countries are turning to thermochemical technologies for the conversion of biomass to biofuels to displace the use of the traditional fossil fuels. A comparative analysis of the potentials of thermochemical conversion technologies of biomass to biofuels and energy in developing countries was conducted. The current status of biomass combustion, cogeneration, gasification, pyrolysis and torrefaction were assessed in different emerging economies, namely, South Africa, Ghana, Malaysia, China, India, Thailand, Tanzania, Brazil and Mauritius. Biomass combustion and cogeneration held the foothold at commercial level both in industrialised and developing countries based on technology maturity and reliability. Biomass gasification is evolving as an eminent method for the production of energy and power in various developing countries. India and China have already embarked on the commercialisation of biomass gasification projects, while other nations have enrolled on pilot-scale schemes. The effectiveness, versatility and environment-friendly aspect of biomass gasification have favoured its preferred integration in the energy system in contrast to combustion and other techniques. Biomass pyrolysis is as promising as gasification in the production of pyrolysis oil to generate transportation fuels. Presently limited at demonstration scale, pyrolysis is being extensively investigated to promote its rapid scale-up and commercial application. Pyrolysis oil represents a crucial resource for the generation of other biofuels, chemicals and power. Torrefaction is a desirable pre-treatment prior to advanced thermal treatment of biomass as it enhances the energy density of processed biomass. Still in its infancy, torrefaction is recurrently being studied to facilitate its large-scale application. The reluctance to adopt biomass thermochemical conversion technologies in developing countries is accounted by economical, technical and social issues. Thermochemical conversion of biomass to biofuel can become important Clean Development Mechanism (CDM) projects with mitigated greenhouse gas (GHG) emissions in the long run.
... Currently, only a few biomass downdraft reactors with RICE have been constructed worldwide, which have become the subject of several research studies. Sharma [66] presented an experimental study performed with the use of a downdraft gasifier coupled with an internal combustion engine. The installation generated electrical power output of 20 kWe and it was pointed out that higher reaction temperatures inside the gasifier tends to enhance its performance. ...
Article
This paper concerns the experimental and numerical analysis of a combined heat and power (CHP) installation equipped with a biomass downdraft gasifier, gas purification system and gas piston engine. The numerical studies were aimed at identifying waste heat in the CHP installation for further utilisation. In turn, a new innovative method of heat recovery inside the gasifier was proposed and subsequently applied in the experimental CHP installation. The newly developed facility is able to produce up to 75 kWe of electrical power. An extensive parametric study was performed under the steady and unsteady facility operation and was supplemented by economic analysis of the process. The main objective of the study was to examine the possibility of sewage sludge gasification and the impact of produced syngas quality on gas engine performance. During the investigation a number of different types of biomass were investigated including wood pellets, sewage sludge and their blends. The results showed a stable operation of the CHP facility in terms of produced syngas load, calorific value and content – even when dried sewage sludge was used alone. Results indicate that a 40/60% blend of wood pellets with sewage sludge is recommended, which allowed the lower heating value (LHV) of 4.45 MJ/Nm³. Additionally, it was confirmed that the fixed bed gasifier is able to self-adjust to temporary changes in gasifier agent load.
... 23 Out of different gasifier design, downdraft gasifier produces a relatively low content of tars in the gas. 24 As a consequence, it may be a preferable choice for small scale decentralized power generation systems via internal combustion engines 25 Biomass gasification is typically performed at moderately high temperatures (700−900°C) which results in the formation of the main components of the producer gas (i.e., CO, H 2 , H 2 O, CO 2 , and CH 4 ) along with other light hydrocarbons (HCs), nitrogen, and byproducts (tar and char), as shown in reaction 1. 26 It is worth mentioning that the nitrogen content can be as high as 50% in the resulting producer gas due to the use of air as gasifying agent. ...
Article
A parametric study of the gasification of six biomass feedstocks (switchgrass, hardwood, softwood, fiber, cardboard and chicken manure), as representative of different types of biomass, has been performed on an experimental, pilot-scale 10 kW down-draft gasification facility. A comparison was made of the performance of the gasifier as a function of feedstock, in terms of the syngas production and composition. The variation of syngas composition was analyzed in the range of 600oC to 1000oC. The results indicated that switchgrass, as representative of energy crops, has greater potential to yield the main components of the syngas (i.e. hydrogen and carbon monoxide) in comparison with the other feedstocks. However, this did not guarantee the greatest suitability of the switchgrass for downstream applications due to low molar ratios of the ratio of hydrogen to carbon monoxide (H2/CO) which measured at 1.01. To enhance the utility efficiency of syngas, the downstream engines such as combustion engines require an adjusted ratio of H2/CO to produce certain types of fuels which typically ranges from 1.5 to 3. By means of the catalytic water-gas shift reaction, an important portion of the CO content in the cracked gas can be used for additional hydrogen generation. The temperature variation of the down-draft reactor showed that the CO concentration increases with an increase in gasification temperature followed by a drop of temperature dependent on the different biomass feedstocks. Conversely, CO2 concentration follows an opposite trend that means an initial decreasing trend followed by an increase as the temperature increases. H2 concentration follows a direct relationship with the gasifier temperature. The concentration of CH4 varies very slightly with the increase in gasifier temperature. The results of this study showed that there were significant differences between the energy crops and chicken manure mixed with wood chip, in terms of composition. In general, the variations in syngas components were smaller at higher temperatures while H2/CO showed greater variation between individual feedstocks.
... The testing of the gasifier cookstoves assembled using the 4 kW th and the 2.5 kW th gasifier prototypes was carried out using the modified Bureau of Indian Standards Protocol IS 13152 (1991) for biomass cookstove testing [11]. Various researchers have conducted experiments on downdraft gasifiers to study the effect of various operating parameters on performance of the gasifiers [12,13,14,15,16,17,18,19,20,21] [ 22,23,24,25,26,27]. ...
Article
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The design methodology available in the literature for downdraft gasifiers of large capacity (∼40–600 kWth) is not directly applicable to very small sized gasifiers. In the present work, design and development of small downdraft gasifiers of 4 kWth and 2.5 kWth nominal capacities, for domestic cookstove application, have been carried out by non-linear extrapolation of data in literature for large gasifiers. The prototypes thus developed were found to give maximum gasification efficiency close to 80%. Extensive experimentation was conducted in the laboratory to study the effect of two operating parameters, viz., gasification air flow rate and the fuel particle size, on the performance of these gasifiers. The performance parameters studied included calorific value of the gas, gasification efficiency, air-biomass ratio and the hearth load. Through detailed analysis of the results, it has been shown that the two operating parameters affect the gasifier performance primarily through their impact on reactor temperature and the total particle surface area available for the reactions. This explains the observation of an optimal gasification air flow rate for best gasification efficiency. It is also shown that the producer gas flow rate varies linearly with gasification air flow rate for a wide range of operating conditions on different sizes of gasifiers. It is also seen that different sizes of the gasifiers can have a different hearth load corresponding to best efficiency.
... One major observation associated with producer gas fuel is a tendency to fluctuate in its composition [13]. This is because of number of factors reported by [14]. These factors pose problems in tuning of producer gas engines precisely. ...
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In this paper an attempt has been reported to bring out the development and testing features of a laboratory scale induction system suited to bottled (fixed composition) PG powered IC engine. A four stroke, single cylinder, spark ignited engine was tested with a bottled PG at a Compression Ratio (CR) of 11:1 and engine speed of 1500 rpm from no-load to full load engine operation. Using suitable throttling devices, a 130 bar supply gas cylinder pressure was conditioned along with other devices to operate engine at Naturally Aspirated (NA) mode. The engine was operated close to stoichiometry condition. The engine supported a peak load of 85 % amounting to a torque of 11.89 N-m and brake power of 1.86 kW against a 2.2 kW gasoline mode. A power loss of 15 % was observed and it was attributed to 25 % lower mixture heating value and 13.33 % lower product to reactant conversion ratio of PG. Overall engine operation was found to be satisfactory. This paper also addresses the need for customizing PG-air mixer and zero pressure regulator.
... Currently, only a few biomass downdraft reactors with RICE have been constructed worldwide, which have become the subject of several research studies. Sharma [66] presented an experimental study performed with the use of a downdraft gasifier coupled with an internal combustion engine. The installation generated electrical power output of 20 kWe and it was pointed out that higher reaction temperatures inside the gasifier tends to enhance its performance. ...
... The pressure gradient across the fixed bed is a function of system geometry, feedstock porosity, permeability, and physical properties of the feedstock (Sharma 2011). Pressure sensors monitor the strength of the pressure gradient in the gasifier. ...
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Biomass gasification shows a great potential to displace fossil fuels. In this study, the gasification of pelletized hard wood using a 10 kW downdraft gasifier is investigated. The variations of pressure and temperature parameters during the gasification process with air as a reagent medium were controlled. The gasifier started in continuous mode to burn the wood pellet feedstock. The results from the continuous mode indicate average temperatures of 838 and 754°C for combustion and reduction zones inside the gasifier, respectively, which shows a low temperature gasification process. Moreover, the pressure in the combustion zone varied on average from −1.30 to −1.64 kPa, while the pressure on top of the main reactor showed average variation of less than 0.07 kPa. The pressure drop is assumed to be caused by bridging of the feedstock, which results in a large part of the feedstock to not flow and be burnt inside the reactor. The shape of feedstock is theorized to be the major reason for the feedstock to bridge, with air leaks in the reactor resulting from sealing challenges intensifying the problem.
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Olive mill solid waste (OMSW), also called olive pomace, is a biomass waste available in many Mediterranean countries, including developing countries. In this study, OMSW has been tested as a fuel in an original pilot-scale downdraft gasifier with three-stage air supply, and extensive metrology was implemented. After pelletizing and characterization of the biomass waste, gasification was investigated by operating a 2-day campaign using air as a gasifying agent. The evolution over time of operating parameters such as flowrates, temperatures and pressure drop were recorded. The syngas (including tars) and solid residues were analyzed. The fate of inorganic elements was investigated. Mass and energy balances were performed and the performance of the gasifier was evaluated. The syngas contained 14 % v/v H2 and 17 % v/v CO (dry and tar-free basis) and its lower heating value was 4.7 MJ/Nm3 (wet basis). The solid residues were rich in potassium and phosphorus and could be considered as an organic amendment. Cold gas efficiency was 68 % and carbon conversion efficiency was 89 %. The points of caution concerned the low melting point of the ash, the relatively high tar content in the syngas and the high NOx content of the flue gases after syngas combustion in a boiler. The energy potential of OMSW is substantial and could help reduce the pressure on fossil fuels.
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This research work examines the performance of an experimental gasification plant fueled with exhausted olive pomace pellets for the concurrent production of electricity, heat and biochar in the olive oil industry. The gasification plant consists of an air-blown downdraft fixed-bed gasifier that generates a lean fuel gas, termed producer gas, in a self-sustaining autothermal process. After conditioning of the producer gas in a cooling and cleaning unit, a four-stroke spark-ignition engine coupled to an electric generator is eventually used as power generation unit. An extensive experimental assessment of this facility was performed under partial and nominal load operation and was supplemented by a physicochemical analysis of the carbonaceous solid material discharged from the gasifier. The mass and energy balances of the gasification plant were calculated, including the carbon conversion efficiency and diverse energy conversion efficiencies. The results revealed an overall stable operation of the gasification plant in terms of composition and heating value of the producer gas and cogenerative production of electricity and heat in the engine--generator set. Under nominal operating conditions, the net electrical efficiency of the gasification plant was 12–13%, with an average carbon conversion efficiency of the biomass feedstock into producer gas just above 80% and an average cold gas efficiency close to 70%.
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This article deals with system development and experimental aspects of a small-scale toroidal fluidized bed gasifier (TFBG) using sawdust feedstock (carpentry waste) with average particle size of 4.18 mm. The reactor and its accessories is designed and constructed. The experiments have been performed to highlight the influence of equivalence ratio on performance parameters (i.e., reaction .temperatures, gas yield, gas composition, heating value and cold gasification efficiency). For variation of equivalence ratio from 0.181 to 0.273 (average basis), the maximum temperature increase from 1015 to 1036 K, combustibles components CO, H2 and CH4 decrease from 16 to 14.9%, 16.3 to 15.3% and 3.5 to 2.3%, respectively and consequently, LHV decreases from 5.454 to 4.716 MJ-kg-1. On qualitative basis, the maximum cold gasification efficiency is observed to be 74 % at equivalence ratio of 0.273, which is considerably higher than fixed bed gasification for sawdust. The overall uncertainty of experimental data is worked out to be ± 3.41 % (i.e., ≤5% within 95% confidence level).
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En este trabajo se presentan los principales resultados investigativos obtenidos por los autores en el modelado para la predicción del poder calorífico del gas de síntesis obtenido en instalaciones de gasificación termoquímica downdraft de la madera de balsa, con la incorporación de técnicas basadas en redes neuronales artificiales. Se realizó un análisis del estudio del estado del arte de trabajos de investigación previos vinculados al modelado matemático de estas instalaciones por las diferentes técnicas reflejada en la literatura especializada. El modelado se lleva a cabo mediante una planificación experimental 3n, con lo que se obtuvo los datos experimentales a los cuales se aplican técnicas de predicción mediante redes neuronales con ayuda de Matlab con resultados satisfactorios. La selección de variables para realizar la experimentación toma en cuenta la ubicación geográfica de donde se obtiene el residuo forestal de la balsa, ya que esta se produce en un clima tropical cálido-húmedo. Por literatura se conoce que uno de los factores que influye notablemente en el poder calorífico es la humedad. Obviamente la cantidad oxígeno contenida en el aire en el proceso es regulada por una válvula de admisión, además de que es un factor preponderante la masa añadida al proceso. Teniendo en cuenta esto, la red neuronal artificial obtenida permite la predicción del poder calorífico resultante de la gasificación de la balsa con un error de ± 2.6 MJ/g y un ajuste del 86%, lo cual permite realizar una predicción adecuada.
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The research results are presented by the authors in the modeling of performance indicators of the operation of biomass gasification facilities through the use of artificial neural networks, starting from the classification of the information derived from the systemic analysis of the operation of these facilities. A bibliographical study of previous research, related to mathematical modeling of these facilities through the different techniques specified on the literature was developed. A 3N experimental plan with 3 replicas is made to generate four models according to their own performance indicators using neural networks, with satisfactory results of their evaluation and based on regression coefficients and standard errors using Eichhornia Crassipes as biomass. The experimental installation and the developed data acquisition systems are described.
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The trend towards decentralised electricity generation and combined heat and power (CHP) is continuously increasing. The transition towards a decentralised power system relies on small-scale and often intermittent generation, bringing new challenges such as matching the demand with supply. A possible solution is the use of renewable energy technologies able to accommodate the demand profile, such as biomass gasification. However, operation at part-load is required and thus limiting the gasification performance efficiency. In this paper, a novel experimental assessment and performance results of a biomass gasification system are presented, consisting on the evaluation of the system performance for steady-state conditions at different loads. Gasifier performance at steady-state conditions showed relatively stable reduction and throat temperatures, with average values of about 729 °C and 915 °C, respectively. These high temperatures assure a producer gas LHV of about 5.5 MJ/kg. Decreasing the gas flow rate resulted in a decrease of both reduction and throat temperatures. Nonetheless, the gas LHV increased until 62.5% where a maximum of about 6 MJ/kg was measured. Concerning the equivalence ratio, it decreased with load, attaining a minimum value at 80%, where the best cold gas efficiency results were found (74%).
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Biomass gasification based power plants can play an important role in power sector in Malaysia with her abundant agricultural and forest resources. In this research energy and economic feasibility , and environmental impact of biomass gasification power plant has been analyzed and assessed for sustainable power generation in Malaysia, the plant being a clean development mechanism supported project. Gasification based power generation with a dual fuel internal combustion engine is found more biomass combustion power plant. But, the annual fuel cost is significantly higher with gasification plant claiming MYR 10 million/y for a generation of 67,500 MWh. The net present value, internal rate of return, and PBP for a 10-MW gasification based dual fuel internal combustion engine power plant without loan financing using empty fruit bunch pellet as biomass; with CER issued at USD16/tCO 2 ; and without loan financing provides net present value, internal rate of return, and PBP of MYR 19.68 million, 11.90%, and 6.05 y, respectively. With a loan financing at 3% per year with CER still be effective the net present value, internal rate of return, and PBP is estimated to be MYR 7.03 million, 3.97%, and 11.78 y, respectively. However, if a 60:40 debt equity is applied then the project net present value, internal rate of return, and payback period seen to improve slightly. The net present value attains a positive
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Worldwide primary energy needs are satisfied basically from non-renewable sources that are limited in supply and innately hazardous to the environment. Biomass-based power systems are very much potent to address the environmental issues fostering sustainable development, while being able to provide a secured and uninterrupted power supply at the same time. Biomass-based power generation systems not only reduce the GHG emissions but also have enormous opportunities of job creation and promote biomass re-growth through sustainable land management practices. This paper overviews the biomass scenario in Southeast Asian and EU countries to give an overview of the potential and scalable energy harnessed from biomass resources. Economic analyses presented on biomass gasification-based power generation have been evaluated with three specific cost estimations, namely low, average and high. Key economic performance metrics of biomass gasification-based dual-fuel internal combustion engine generator with low investment estimates are as follows: a positive net present value of USD 7.5 million; internal rate of return 14.45%; and a payback period of 5.45 years. A review of the technologies can provide a base for strategic energy policy for the next generation of sustainable energy policies and helps policymakers to frame strategies aiming for clean technology and sustainable development. Biomass integrated gasification combined cycle-based systems are found to be most suitable for power generation or biofuel synthesis. Graphic abstract
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In order to enhance the quality of producer gas obtained from the biomass gasification process without the use of oxygen, high temperature air-steam gasification may be an advantageous technology. A highly preheated agent (air and steam) can provide additional energy into the process that improves thermal decomposition of the gasified biomass feedstock, and promotes endothermic reactions. In this investigation, the high temperature air-stream gasification process was performed on a fixed-bed downdraft biomass gasifier. The results showed that increasing the gasifying agent preheat temperature led to increased concentrations of H2 and CO and decreased contaminated tar in the producer gas. Increasing the equivalence ratio resulted in decreased H2 and CO concentrations and also reduced tar content. The introduction of steam increased gas quality, but excessive steam degraded gas quality. The increased higher heating value of the gasified gas varied between 4.15 and 6.21 MJ/Nm³.
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The study attempts at developing an artificial neural network (ANN) based model of biomass gasification in fixed bed downdraft gasifiers. The study is a novel attempt in developing an ANN based model of biomass gasification in fixed bed downdraft gasifiers as there are very few reported studies of ANN based modeling of biomass gasification in general and even fewer in the field of fixed bed downdraft gasifiers. In fact, downdraft gasifiers are one of the most widely used type of gasifiers for small scale operation. The ANN based models were formulated to predict the product gas composition in terms of concentration of four major gas species viz. CH4%, CO%, CO2% and H2%. The input parameters used in the models were C, H, O content, ash content, moisture content, and reduction zone temperature. The architecture of the models consisted of one input, one hidden and one output layer. Reported experimental data were used to train the ANNs. The output of the ANN models were found to be in agreement with experimental data with an absolute fraction of variance (R²) higher than 0.99 in the cases of CH4 and CO models and higher than 0.98 in the case of CO2 and H2 model. The results show the possibility of utilization of the model to predict the percentage composition of four major product gas species (CH4, CO, CO2 and H2). The relative importance of the input variables was also analysed using the Garson's equation.
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The need for sustainable alternatives to oil has been of deep concern to many countries around the world, and especially the U.S. due to the rapidly rising cost of oil. As a result, many nations face significant energy security challenges stemming from their dependence on imported oil. To achieve future energy security and independence and in the long run to prepare for the post-oil energy resources, biomass is considered as one of the most important renewable energy resources in a projected sustainable energy future. The key bottleneck for lignocellulosic-derived biofuels is the lack of technology for efficient conversion of biomass in to readily usable fuel products. Current work provides a detailed theoretical and experimental analysis of two (air and steam only) gasification technologies which are carbon neutral that can be used to overcome this hurdle. This work also examines the use of mixed ion-electron conductors (MIEC) membranes as a significant option to enhance the production of H2 from biomass feedstock. Currently there are technologies that produce H2 by using renewable energy sources other than biomass as feedstock but they could not provide a long term solution because of their adverse effects on eco-system. Thin film SrCe0.7Zr0.2Eu0.1 O3-δ membranes were developed and supported using NiO-SrCe0.8 Zr0.2 O3-δ tubular structure, using Dr. Eric Wachsman’s group’s work at UF. The main advantage of this membrane setup is that it acts as WGS reactor and also separates the H2 from the gas stream, thus avoiding the need for two stage reactor setup requiring WGS and H2 separation independently. The possibility of sequestering the isolated CO2 stream is also another attribute to such membrane reactors. The overall objective of this current work is to analyze the air gasification and steam only gasification technology in detail and to investigate the performance of proton conducting ceramic membranes at high temperatures. Current research also analyzed a simplistic model of a concept system, which is a self-sustaining H2 fuel production system that integrates the gasification technology and the MIEC membrane technology. The proposed system enhances the H2 produced from the biomass feed stock by carrying out WGS.
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The open top gasifier technology developed by the R&D team at the Combustion, Gasification and Propulsion Laboratory, CGPL, of the Indian Institute of Science, Bangalore, successfully ran irrigation pumping sets, where it replaced diesel oil by producer gas. The technology was subsequently further developed for power generation, also with promising results. A laboratory - industry cooperation between IISc and DASAG, established to engineer the technology to rigorous power plant standards before commercialising it, has progressed into a successful South - North technology partnership being supported by the Swiss and the Indian governments. The paper describes the gasifier and presents details of its performance both in the laboratory and in the field, including experience of a plant running in an Indian village, results of tests carried out jointly by Indo-Swiss teams in Bangalore and the results of the initial operation of a plant in Chatel-St-Denis, Switzerland. Details of a commercial 80 kWe cogeneration plant supplying electricity and process heat for drying to a hand-made paper factory have also been presented. The paper gives details of steps taken to commercialise the technology and puts forward the concept of Independent Rural Power Producers IRPPs for setting up decentralised power stations in villages. The paper presents data on the cost of power generation in biomass based Independent Rural Power Producers (IRPPs) and compares the economics of electricity supplied from such decentralised plants with those of coal based electricity supplied by the Indian power grid.
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In the development of rural India, employment generation is the most fundamental issue to be addressed, which, in today's context, is very closely connected to the power supply to villages. Decentralised power supply is being increasingly recognised as having much greater potential for supplying quality power to the remote areas as compared to the conventional centralised supply. Biomass gasification has emerged as a very promising technology for decentralised power generation and hence must be utilised for rural electrification to its full potential. In this paper, an effort has been made to draw attention to the suitability of this technology for power supply to villages and also to the challenges which must be addressed for effective use of the technology for this purpose. Many issues which need careful consideration, like resource and demand assessment, various aspects of plant management, economics and the government policies have been discussed. Many of these are pertaining to field situations and hence pose considerable challenge for effective handling. The paper is directed towards a wide class of readership – from those responsible for rural electrification including policy makers and implementers, who may need to know even the basics of the technology to those familiar with technology but with little or no experience in field implementation. It is hoped that such a paper will provide the concerned people with adequate exposure to the complexities associated with rural electrification using biomass gasification and hence help in its more effective implementation.
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An experimental investigation of a downdraft biomass gasifier is carried out using furniture wood and wood chips. The effect of equivalence ratio on the gas composition, calorific value and the gas production rate is presented. The calorific value of the producer gas increases with equivalence ratio initially, attains a peak and then decreases with the increase in equivalence ratio. The gas flow rate per unit weight of the fuel increases linearly with equivalence ratio. It is also observed that complete conversion of carbon to gaseous fuel has not taken place even for the optimum equivalence ratio.
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The potential offered by biomass to reduce greenhouse gas production is now being more widely recognised. The energy in biomass may be realised either by direct combustion use, or by upgrading into more valuable and useable products such as gas, fuel oil and higher value products for utilisation in the chemical industry or for clean power generation. Up till now, gasification work has concentrated on woody biomass but recently sources of other biomass with large energy production potential have been identified, namely hazelnut shells. Therefore, a pilot scale downdraft gasifier is used to investigate gasification potential of hazelnut shells. A full mass balance is reported including the tar production rate as well as the composition of the produced gas as a function of feed rate. Additionally, the effect of feed rate on the CV/composition of the product gas and the associated variations of gasifier zone temperatures are determined with temperatures recorded throughout the main zones of the gasifier and also at the gasifier outlet and gas cleaning zones. Pressure drops are also measured across the gasifier and gas cleaning system because the produced gas may be used in conjunction with a power production engine when it is important to have low pressure drop in the system. The quality of the product gas is found to be dependent on the smooth flow of the fuel and the uniformity of the pyrolysis, and so the difficulties, encountered during the experiments are detailed. The optimum operation of the gasifier is found to be between 1.44 and 1.47 N m3/kg of air fuel ratios at the values of 4.06 and 4.48 kg/h of wet feed rate which produces the producer gas with a good GCV of about 5 MJ/m3 at a volumetric flow of 8–9 N m3/h product gas. It was concluded that hazelnut shells could be easily gasified in a downdraft gasifier to produce good quality gas with minimum polluting by-products. It is suggested that, in view of ease of operation, small-scale gasifiers can make an important contribution to the economy of rural areas where the residues of nuts are abundant. It is also suggested that gasification of shell waste products is a clean alternative to fossil fuels and the product gas can be directly used in internal gas combustion engines, thus warranting further investment/encouragement by authorities to exploit this valuable resource.
Article
The work with a 100-kWth two-stage gasifier at the Technical University of Denmark (DTU) has resulted in a gas with a very low tar content. The reduction in tar has come about by combining the partial oxidation of the pyrolysis gas with the reactions that follow on a charcoal bed in the char gasification unit. Tar is defined as organic contaminants which have retention times equal to or greater than those of phenol on a nonpolar GC column. Two test series were made with wood chips as feedstock, before and after the gasifier was optimized. The effect on tar reduction of a charcoal bed has been investigated by measuring the tar content and composition of the gas after the partial oxidation (above the charcoal bed) and after the passage of the gas through the charcoal. By introducing the correct supply of air, the tar content in the gas after its partial oxidation was about 3000 mg/kg dry wood chips. Furthermore, a conclusive high tar reduction of the aromatic hydrocarbons including PAH was obtained by avoiding bypasses of the charcoal bed. A gas was produced with a tar content as low as 10−40 mg/kg dry wood.
Article
Tar is the most undesirable contaminant of producer gas. Production of tar-free gas from uncarbonized biomass seems to be rather elusive, and removing tar from the gas remains a daunting task requiring bulky, expensive equipment and considerable operational effort. A new multi-stage reactor design has been developed in order to separate the flaming-pyrolysis zone from the reduction zone. Tar vapors generated in the first zone are burned or cracked to simple molecules by high temperature in the second zone. Data obtained from experimental tests show that the two-stage reactor has improved gas quality and conversion efficiency. The tar content of the gas is about 40 times less than that obtained with a single-stage reactor under similar operating conditions.
Article
The effect of woody biomass components on air-steam gasification was investigated using the downdraft fixed-bed gasifier at 1173K and at atmospheric pressure. Cellulose, xylan, and lignin as model compounds of woody biomass components, and Japanese oak and Japanese red pine bark as woody biomass were employed as feedstock. The gasification conversions in cellulose, xylan, and lignin were 97.9%, 92.2%, and 52.8% on a carbon basis, respectively. In each run, the main components of the gas phase were CO, CO2, H2, and CH4. The product gas composition in cellulose was 35.5mol% CO, 27.0mol%CO2, and 28.7mol%H2, and the CO composition was higher than the CO2 or H2 compositions, which was similar to that in the Japanese oak, of which the main component was cellulose. In contrast, the product gas compositions in xylan and lignin were approximately 25mol% CO, 36mol%CO2, and 32mol%H2, and the CO composition was lower than the CO2 or H2 compositions, which were similar to those in Japanese red pine bark, of which the main component was lignin. These results suggest that the fundamental information obtained in the gasification of each component could possibly be used to predict the composition of product gas generated in air-steam gasification of woody biomass.
Article
The paper describes the performance and operational experience in India on a high efficiency, low tar, woody biomass gasifier developed at Indian Institute of Science, Bangalore. This development is also of interest to Switzerland, which has a substantial potential of biomass energy. The test scheme included measurements on tar and particulates and the effluents along with necessary measurements for the mass and energy balance. The results indicate a low tar level to meet the engine specifications and the effluents issuing out of the system could be treated using simpler techniques, as the levels are low.
Article
This paper reports the commercial-scale (1080 MJ h−1) development of a gasification system using low-density biomass, for thermal applications. The gasifier can handle fuels such as sugarcane leaves and bagasse, bajra stalks, sweet sorghum stalks and bagasse etc. The system was tested for > 700 h under laboratory conditions at 288–1080 MJ h−1 output levels. The HHV of the gas was 3.56–4.82 MJ m−3 (s.t.p.). The system also produces char. ∼ 24wt% of the original fuel. It can be briquetted to form an excellent fuel for wood stoves or can be used as a soil conditioner. After successful laboratory trial, the system was also tested at a metallurgical company, where it was retrofitted to an oil-fired furnace for baking speciality ceramics. The furnace was operated exclusively on the gasification system and the product quality was on a par with, if not better than, that obtained during oil-fired operation. The economics of the system are also presented.
Article
A laboratory-scale countercurrent fixed-bed gasification plant has been designed and constructed to produce data for process modeling and to compare the gasification characteristics of several biomasses (beechwood, nutshells, olive husks, and grape residues). The composition of producer gas and spatial temperature profiles have been measured for biomass gasification at different air flow rates. The gas-heating value always attains a maximum as a function of this operating variable, associated with a decrease of the air-to-fuel ratio. Optimal gasification conditions of wood and agricultural residues give rise to comparable gas-heating values, comprised in the range 5−5.5 MJ/Nm3 with 28−30% CO, 5−7% CO2, 6−8% H2, 1−2% CH4, and small amounts of C2− hydrocarbons (apart from nitrogen). However, gasification of agricultural residues is more difficult because of bed transport, partial ash sintering, nonuniform flow distribution, and the presence of a muddy phase in the effluents, so that proper pretreatments are needed for large-scale applications.
Article
A gasifier has been fabricated in Sri Lanka for the tea industry, but there is a lack of knowledge of the effect of certain key operating parameters and design features on its performance. Experimental testing of the design under various conditions has produced data that has then been used to calibrate a computer program, developed to investigate the impact of those parameters and features on conversion efficiency. The program consists of two sub-models of the pyrolysis and gasification zones, respectively. The pyrolysis sub-model has been used to determine the maximum temperature and the composition of the gas entering the gasification zone. The gasification zone sub-model has been calibrated using data gathered from the experiments. It was found that a wood chip size of 3– with a moisture content below 15% (d.b.) should be used in this gasifier. Feed material with a fixed carbon content of higher than 30% and heat losses of more than 15% should be avoided. For the above parameters, the gasification zone should be long to achieve an acceptable conversion efficiency.
Article
A process of conversion of solid carbonaceous fuel into combustible gas by partial combustion is known as gasification. The resulting gas, known as producer gas, is more versatile in its use than the original solid biomass. In the present study, a downdraft biomass gasifier is used to carry out the gasification experiments with the waste generated while making furniture in the carpentry section of the institute’s workshop. Dalbergia sisoo, generally known as sesame wood or rose wood is mainly used in the furniture and wastage of the same is used as a biomass material in the present gasification studies. The effects of air flow rate and moisture content on biomass consumption rate and quality of the producer gas generated are studied by performing experiments. The performance of the biomass gasifier system is evaluated in terms of equivalence ratio, producer gas composition, calorific value of the producer gas, gas production rate, zone temperatures and cold gas efficiency. Material balance is carried out to examine the reliability of the results generated. The experimental results are compared with those reported in the literature.
Article
A fluid flow and heat transfer model has been developed for the reactive, porous bed of the biomass gasifier to simulate pressure drop, temperature profile in the bed and flow rates. The conservation equations, momentum equation and energy equation are used to describe fluid and heat transport in porous gasifier bed. The model accounted for drag at wall, and the effect of radial as well as axial variation in bed porosity to predict pressure drop in bed. Heat transfer has been modeled using effective thermal conductivity approach. Model predictions are validated against the experiments, while effective thermal conductivity values are tested qualitatively using models available in literature. Parametric analysis has been carried out to investigate the effect of various parameters on bed temperature profile and pressure drop through the gasifier. The temperature profile is found to be very sensitive to gas flow rate, and heat generation in oxidation zone, while high bed temperature, gas flow rate and the reduction in feedstock particle size are found to cause a marked increase in pressure drop through the gasifier. The temperatures of the down stream zones are more sensitive to any change in heat generation in the bed as compared to upstream zone. Author recommends that the size of preheating zone may be extended up to pyrolysis zone in order to enhance preheating of input air, while thermal insulation should not be less than 15 cm.
Article
The use of sawmill residues must be carefully analyzed to offer the best technical, economic and environmental alternative. The characterization (quantity, type, chemical and energetic analysis) of the residues generated, in addition to the energetic needs of sawmills, is essential to determine which technology is more suitable. This study shows that the technology of wood gasification can produce a gas able to be burned in an internal combustion engine, as long as it is appropriately cleaned. In order to assess the performance of the wood residues gasification process, a small, fixed bed, downdraft, stratified and open top gasifier was built. This gasifier, whose capacity was around 12 kg/h, has an internal gas recirculation, new to this type of gasifier, which can burn part of the gas produced to raise the gasification reaction temperature. Through the several parameters measured in the experiments, the mass and energy balances of the gasifier studied were obtained and its cold gas, global and mass conversion efficiencies were determined.
Thermochemiocal characterisation of biomass residues for gasification
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Grover PD, Baveja KK, Rao TR, Iyer PVR. Thermochemiocal characterisation of biomass residues for gasification, vol. I. Delhi: Biomass Research Laboratory, IIT; 1988.
Experiments and modelling studies of producer gas based spark-ignited reciprocating engines
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Rao SG. Experiments and modelling studies of producer gas based spark-ignited reciprocating engines [PhD thesis]. Indian Institute of Science, Bangalore, INDIA; 2003.
Simulation of biomass gasifier-engine system
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Sharma AK. Simulation of biomass gasifier-engine system [PhD thesis]. Indian Institute of Technology, Delhi, India; 2006.