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Biomass Gasifier

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Avdhesh Kr Sharma – One of the best experts on this subject based on the ideXlab platform.

  • modeling and simulation of a downdraft Biomass Gasifier 1 model development and validation
    Energy Conversion and Management, 2011
    Co-Authors: Avdhesh Kr Sharma

    Abstract:

    An ‘EQB’ computer program for a downdraft Gasifier has been developed to predict steady state performance. Moving porous bed of suction Gasifier is modeled as one-dimensional (1-D) with finite control volumes (CVs), where conservation of mass, momentum and energy is represented by fluid flow, heat transfer analysis, drying, pyrolysis, oxidation and reduction reaction modules; which have solved in integral form using tri-diagonal matrix algorithm (TDMA) for reaction temperatures, pressure drop, energetics and product composition. Fluid flow module relates the flow rate with pressure drop, while Biomass drying is described by mass transfer 1-D diffusion equation coupled with vapour–liquid-equilibrium relation. When chemical equilibrium is used in oxidation zone, the empirically predicted pyrolysis products (volatiles and char) and kinetic modeling approach for reduction zone constitutes an efficient algorithm allowing rapid convergence with adequate fidelity. Predictions for pressure drop and power output (Gasifier) are found to be very sensitive, while gas composition or calorific value, temperature profile and gasification efficiency are less sensitive within the encountered range of gas flow rate.

  • experimental study on 75 kwth downdraft Biomass Gasifier system
    Renewable Energy, 2009
    Co-Authors: Avdhesh Kr Sharma

    Abstract:

    Experimental study on 75kWth, downdraft (Biomass) Gasifier system has been carried out to obtain temperature profile, gas composition, calorific value and trends for pressure drop across the porous Gasifier bed, cooling–cleaning train and across the system as a whole in both firing as well as non-firing mode. Some issues related to re-fabrication of damaged components/parts have been discussed in order to avoid any kind of leakage. In firing mode, the pressure drop across the porous bed, cooling–cleaning train, bed temperature profile, gas composition and gas calorific value are found to be sensitive to the gas flow rate. The rise in the bed temperature due to chemical reactions strongly influences the pressure drop through the porous Gasifier bed. In non-firing mode, the extinguished Gasifier bed arrangement (progressively decreasing particle size distribution) gives much higher resistance to flow as compared to a freshly charged Gasifier bed (uniformly distributed particle size). The influence of ash deposition in fired-Gasifier bed and tar deposition in sand filters is also examined on the pressure drop through them. The experimental data generated in this article may be useful for validation of any simulation codes for Gasifiers and the pressure drop characteristics may be useful towards the coupling of a Gasifier to the gas engine for motive power generation or decentralized electrification applications.

  • equilibrium and kinetic modeling of char reduction reactions in a downdraft Biomass Gasifier a comparison
    Solar Energy, 2008
    Co-Authors: Avdhesh Kr Sharma

    Abstract:

    Abstract The thermodynamic and kinetic modeling of char reduction reactions in a downdraft (Biomass) Gasifier has been presented. Mass and energy balance are coupled with equilibrium relations or kinetic rate parameters (using varying char reactivity factor) in order to predict status of un-converted char in addition to gas composition, calorific value, conversion efficiency, exit gas temperature, endothermic heat absorption rate and Gasifier power output. Both modeling predictions are compared against experimental data for their validity. The influence of char bed length and reaction temperature in reduction zone has been examined. CO and H 2 component, calorific value of product gas and the endothermic heat absorption rate in reduction zone are found to be sensitive with reaction temperature, while char bed length is less sensitive to equilibrium predictions. For present case, all char conversion takes place at critical reaction temperature of 932 K for equilibrium, while for kinetic modeling critical reaction temperature and critical char bed length of 950 K and ∼25 cm have been identified, comparing the predictions. The critical reaction temperatures and critical char bed length also depend on inlet components composition and initial temperature supplied to the reduction reaction zone model.

W. Zhang – One of the best experts on this subject based on the ideXlab platform.

  • experimental test on a novel dual fluidised bed Biomass Gasifier for synthetic fuel production
    Fuel, 2011
    Co-Authors: Kristina Göransson, Ulf Söderlind, W. Zhang

    Abstract:

    This article presents a preliminary test on the 150 kWth allothermal Biomass Gasifier at MIUN (Mid Sweden University) in Harnosand, Sweden. The MIUN Gasifier is a combination of a fluidised bed gas …

  • Experimental test on a novel dual fluidised bed Biomass Gasifier for synthetic fuel production
    Fuel, 2011
    Co-Authors: Kristina Göransson, Ulf Söderlind, W. Zhang

    Abstract:

    This article presents a preliminary test on the 150 kWthallothermal Biomass Gasifier at Mid Sweden University (MIUN) in Härnösand, Sweden. The MIUN Gasifier is a combination of a fluidised bed Gasifier and a CFB riser as a combustor with a design suitable for in-built tar/CH4catalytic reforming. The test was carried out by two steps: (1) fluid-dynamic study; (2) measurements of gas composition and tar. A novel solid circulation measurement system which works at high bed temperatures is developed in the presented work. The results show the dependency of bed material circulation rate on the superficial gas velocity in the combustor, the bed material inventory and the aeration of solids flow between the bottoms of the Gasifier and the combustor. A strong influence of circulation rate on the temperature difference between the combustor and the Gasifier was identified. The syngas analysis showed that, as steam/Biomass (S/B) ratio increases, CH4content decreases and H2/CO ratio increases. Furthermore the total tar content decreases with increasing steam/Biomass ratio and increasing temperature. The Biomass gasification technology at MIUN is simple, cheap, reliable, and can obtain a syngas of high CO+H2concentration with sufficient high ratio of H2to CO, which may be suitable for synthesis of methane, DME, FT-fuels or alcohol fuels. The measurement results of MIUN Gasifier have been compared with other Gasifiers. The main differences can be observed in the H2and the CO content, as well as the tar content. These can be explained by differences in the feed systems, operating temperature, S/B ratio or bed material catalytic effect, etc. © 2011 Elsevier Ltd All rights reserved.

  • Experimental test on a novel dual fluidised bed Biomass Gasifier for synthetic fuel production
    Fuel, 2011
    Co-Authors: K Goeransson, U Soederlind, W. Zhang

    Abstract:

    This article presents a preliminary test on the 150 kW allothermal Biomass Gasifier at Mid Sweden University (MIUN) in Haernoesand, Sweden. The MIUN Gasifier is a combination of a fluidised bed Gasifier and a CFB riser as a combustor with a design suitable for in-built tar/CH sub(4) catalytic reforming. The test was carried out by two steps: (1) fluid-dynamic study; (2) measurements of gas composition and tar. A novel solid circulation measurement system which works at high bed temperatures is developed in the presented work. The results show the dependency of bed material circulation rate on the superficial gas velocity in the combustor, the bed material inventory and the aeration of solids flow between the bottoms of the Gasifier and the combustor. A strong influence of circulation rate on the temperature difference between the combustor and the Gasifier was identified. The syngas analysis showed that, as steam/Biomass (S/B) ratio increases, CH sub(4) content decreases and H sub(2)/CO ratio increases. Furthermore the total tar content decreases with increasing steam/Biomass ratio and increasing temperature. The Biomass gasification technology at MIUN is simple, cheap, reliable, and can obtain a syngas of high CO + H sub(2) concentration with sufficient high ratio of H sub(2) to CO, which may be suitable for synthesis of methane, DME, FT-fuels or alcohol fuels. The measurement results of MIUN Gasifier have been compared with other Gasifiers. The main differences can be observed in the H sub(2) and the CO content, as well as the tar content. These can be explained by differences in the feed systems, operating temperature, S/B ratio or bed material catalytic effect, etc.

Rubenildo V. Andrade – One of the best experts on this subject based on the ideXlab platform.

  • Theoretical and experimental investigations of a downdraft Biomass Gasifier-spark ignition engine power system
    Renewable Energy, 2012
    Co-Authors: Felipe Centeno, Khamid Mahkamov, Electo E. Silva Lora, Rubenildo V. Andrade

    Abstract:

    A mathematical model which was developed to predict steady state performance of a Biomass downdraft Gasifier/spark ignition engine power system is described. A mathematical model of the integrated system consists of two parts: the fixed bed downdraft Gasifier and spark ignition internal combustion engine models. For calculations the Gasifier is split into three zones, namely drying – pyrolysis, oxidation and reduction sections. The Gasifier‘s mathematical model consists of three separate sub-models, each describing the processes in the corresponding zone. The process taking place in the reduction zone has been described using chemical kinetic principles in order to avoid introduction of assumptions related to achievement of the thermo-chemical equilibrium state during Gasifier‘s operation. The model is capable to accurately predict molar concentrations of different species in syngas (CO2, CO, H2O, H2, CH4and N2) and the temperature profile in the Gasifier along its height. This information then can be used for sizing the reactor and material selection. The engine’s model is based on the fuel-air thermodynamic cycle for spark ignition engines and such model takes into account the composition of syngas used as fuel. The engine’s model also takes into account effects of heat losses in the cycle through the walls of the cylinders and due to the gas blow by. Finally, the influence of dissociation processes during the combustion and the residual gases remaining in the cylinders at the beginning of the compression stroke is accounted for computations of the engine’s performance. The numerical results obtained using the proposed model are in a good agreement with data produced with the use of other theoretical models and experimental data published in open literature and with experimental data obtained in these investigations. The proposed model is applicable for modelling integrated downdraft Gasifier/engine Biomass energy systems and can be used for more accurate adjustment of design parameters of the Gasifier and the engine in order to provide the higher overall efficiency of the system. © 2011 Elsevier Ltd.

  • theoretical and experimental investigations of a downdraft Biomass Gasifier spark ignition engine power system
    Renewable Energy, 2012
    Co-Authors: Felipe Centeno, Khamid Mahkamov, Electo Eduardo Silva Lora, Rubenildo V. Andrade

    Abstract:

    A mathematical model which was developed to predict steady state performance of a Biomass downdraft Gasifier/spark ignition engine power system is described. A mathematical model of the integrated system consists of two parts: the fixed bed downdraft Gasifier and spark ignition internal combustion engine models. For calculations the Gasifier is split into three zones, namely drying – pyrolysis, oxidation and reduction sections. The Gasifier’s mathematical model consists of three separate sub-models, each describing the processes in the corresponding zone. The process taking place in the reduction zone has been described using chemical kinetic principles in order to avoid introduction of assumptions related to achievement of the thermo-chemical equilibrium state during Gasifier’s operation. The model is capable to accurately predict molar concentrations of different species in syngas (CO2, CO, H2O, H2, CH4 and N2) and the temperature profile in the Gasifier along its height. This information then can be used for sizing the reactor and material selection. The engine’s model is based on the fuel–air thermodynamic cycle for spark ignition engines and such model takes into account the composition of syngas used as fuel. The engine’s model also takes into account effects of heat losses in the cycle through the walls of the cylinders and due to the gas blow by. Finally, the influence of dissociation processes during the combustion and the residual gases remaining in the cylinders at the beginning of the compression stroke is accounted for computations of the engine’s performance. The numerical results obtained using the proposed model are in a good agreement with data produced with the use of other theoretical models and experimental data published in open literature and with experimental data obtained in these investigations. The proposed model is applicable for modelling integrated downdraft Gasifier/engine Biomass energy systems and can be used for more accurate adjustment of design parameters of the Gasifier and the engine in order to provide the higher overall efficiency of the system.