The Experts below are selected from a list of 1959 Experts worldwide ranked by ideXlab platform

Filip Johnsson - One of the best experts on this subject based on the ideXlab platform.

  • heat transfer in a 4 mwth circulating Fluidized Bed Furnace operated under oxy fired and air fired conditions modeling and measurements
    International Journal of Greenhouse Gas Control, 2015
    Co-Authors: Sadegh Seddighi Khavidak, David Pallarès, Filip Johnsson, Fredrik Normann, Ville Ylaoutinen
    Abstract:

    Heat transfer to wall panels in the Furnace of a circulating Fluidized Bed (CFB) is investigated by means of a 1.5-dimensional mathematical model together with measurements from a 4-MWth CFB unit under air and oxy-fuel conditions. The conditions at the wall panels correspond to solids concentration between 0.35 and 18 kg/m3 and temperatures between 1054 and 1168 K. The heat transfer coefficient to the wall panels is similar in oxy-fuel and air-firing due to that the solids flow, which plays the main role in CFB Furnace heat transfer, was kept similar in air and oxyfuel conditions. The modeled Furnace heat extraction and in-Furnace vertical profiles of temperature and solids concentration show generally good agreement with the corresponding measured values. Modeling results show that for all cases studied, the share of radiation in the total Furnace heat extraction exceeds 70% and increases with the increase in Furnace temperature. Modeling results also show that gas radiation has a small influence on Furnace heat extraction.

  • progress of combustion in an oxy fuel circulating Fluidized Bed Furnace measurements and modeling in a 4 mwth boiler
    Energy & Fuels, 2013
    Co-Authors: Sadegh K Seddighi, David Pallarès, Fredrik Normann, Filip Johnsson
    Abstract:

    Oxy-fuel combustion, which is a promising technology for the abatement of carbon dioxide emissions, can be applied in circulating Fluidized-Bed (CFB) power plants. In this study, the effects of operational conditions on the progress of oxy-fuel CFB combustion were investigated by means of a mathematical model for CFB oxy-fuel combustion together with experimental data from a 4 MWth oxy-fuel CFB, currently representing the largest oxy-fuel CFB combustion experiments in the literature. Modeled in-Furnace profiles for carbon monoxide (CO) and oxygen (O2) were compared to the corresponding measurements, yielding a general good agreement for both air- and oxy-fuel-fired conditions. The developed model was also used to investigate the effects of varying the inlet O2 concentration over a wider range than that applied in the experiments. The experimental results show that, for an equivalent inlet O2 concentration, the peak CO concentration is higher under oxy-fuel-fired conditions than under air-fired conditions. The model result shows that a higher inlet O2 concentration generates combustion of greater intensity up through the Furnace with a lower level of CO at the Furnace exit.

Zhiwei Wang - One of the best experts on this subject based on the ideXlab platform.

  • biomass steam gasification in bubbling Fluidized Bed for higher h2 syngas cfd simulation with coarse grain model
    International Journal of Hydrogen Energy, 2019
    Co-Authors: Tian Qi, Guanyi Chen, Zhongshan Li, Hesameddin Fatehi, Zhiwei Wang
    Abstract:

    Abstract A comprehensive coarse grain model (CGM) is applied to simulation of biomass steam gasification in bubbling Fluidized Bed reactor. The CGM was evaluated by comparing the hydrodynamic behavior and heat transfer prediction with the results predicted using the discrete element method (DEM) and experimental data in a lab-scale Fluidized Bed Furnace. CGM shows good performance and the computational time is significantly shorter than the DEM approach. The CGM is used to study the effects of different operating temperature and steam/biomass (S/B) ratio on the gasification process and product gas composition. The results show that higher temperature enhances the production of CO, and higher S/B ratio improves the production of H2, while it suppresses the production of CO. For the main product H2, the minimum relative error of CGM in comparison with experiment is 1%, the maximum relative error is less than 4%. For the total gas yield and H2 gas yield, the maximum relative errors are less than 7%. The predicted concentration of different product gases is in good agreement with experimental data. CGM is shown to provide reliable prediction of the gasification process in Fluidized Bed Furnace with considerably reduced computational time.

Fredrik Normann - One of the best experts on this subject based on the ideXlab platform.

  • heat transfer in a 4 mwth circulating Fluidized Bed Furnace operated under oxy fired and air fired conditions modeling and measurements
    International Journal of Greenhouse Gas Control, 2015
    Co-Authors: Sadegh Seddighi Khavidak, David Pallarès, Filip Johnsson, Fredrik Normann, Ville Ylaoutinen
    Abstract:

    Heat transfer to wall panels in the Furnace of a circulating Fluidized Bed (CFB) is investigated by means of a 1.5-dimensional mathematical model together with measurements from a 4-MWth CFB unit under air and oxy-fuel conditions. The conditions at the wall panels correspond to solids concentration between 0.35 and 18 kg/m3 and temperatures between 1054 and 1168 K. The heat transfer coefficient to the wall panels is similar in oxy-fuel and air-firing due to that the solids flow, which plays the main role in CFB Furnace heat transfer, was kept similar in air and oxyfuel conditions. The modeled Furnace heat extraction and in-Furnace vertical profiles of temperature and solids concentration show generally good agreement with the corresponding measured values. Modeling results show that for all cases studied, the share of radiation in the total Furnace heat extraction exceeds 70% and increases with the increase in Furnace temperature. Modeling results also show that gas radiation has a small influence on Furnace heat extraction.

  • progress of combustion in an oxy fuel circulating Fluidized Bed Furnace measurements and modeling in a 4 mwth boiler
    Energy & Fuels, 2013
    Co-Authors: Sadegh K Seddighi, David Pallarès, Fredrik Normann, Filip Johnsson
    Abstract:

    Oxy-fuel combustion, which is a promising technology for the abatement of carbon dioxide emissions, can be applied in circulating Fluidized-Bed (CFB) power plants. In this study, the effects of operational conditions on the progress of oxy-fuel CFB combustion were investigated by means of a mathematical model for CFB oxy-fuel combustion together with experimental data from a 4 MWth oxy-fuel CFB, currently representing the largest oxy-fuel CFB combustion experiments in the literature. Modeled in-Furnace profiles for carbon monoxide (CO) and oxygen (O2) were compared to the corresponding measurements, yielding a general good agreement for both air- and oxy-fuel-fired conditions. The developed model was also used to investigate the effects of varying the inlet O2 concentration over a wider range than that applied in the experiments. The experimental results show that, for an equivalent inlet O2 concentration, the peak CO concentration is higher under oxy-fuel-fired conditions than under air-fired conditions. The model result shows that a higher inlet O2 concentration generates combustion of greater intensity up through the Furnace with a lower level of CO at the Furnace exit.

David Pallarès - One of the best experts on this subject based on the ideXlab platform.

  • heat transfer in a 4 mwth circulating Fluidized Bed Furnace operated under oxy fired and air fired conditions modeling and measurements
    International Journal of Greenhouse Gas Control, 2015
    Co-Authors: Sadegh Seddighi Khavidak, David Pallarès, Filip Johnsson, Fredrik Normann, Ville Ylaoutinen
    Abstract:

    Heat transfer to wall panels in the Furnace of a circulating Fluidized Bed (CFB) is investigated by means of a 1.5-dimensional mathematical model together with measurements from a 4-MWth CFB unit under air and oxy-fuel conditions. The conditions at the wall panels correspond to solids concentration between 0.35 and 18 kg/m3 and temperatures between 1054 and 1168 K. The heat transfer coefficient to the wall panels is similar in oxy-fuel and air-firing due to that the solids flow, which plays the main role in CFB Furnace heat transfer, was kept similar in air and oxyfuel conditions. The modeled Furnace heat extraction and in-Furnace vertical profiles of temperature and solids concentration show generally good agreement with the corresponding measured values. Modeling results show that for all cases studied, the share of radiation in the total Furnace heat extraction exceeds 70% and increases with the increase in Furnace temperature. Modeling results also show that gas radiation has a small influence on Furnace heat extraction.

  • progress of combustion in an oxy fuel circulating Fluidized Bed Furnace measurements and modeling in a 4 mwth boiler
    Energy & Fuels, 2013
    Co-Authors: Sadegh K Seddighi, David Pallarès, Fredrik Normann, Filip Johnsson
    Abstract:

    Oxy-fuel combustion, which is a promising technology for the abatement of carbon dioxide emissions, can be applied in circulating Fluidized-Bed (CFB) power plants. In this study, the effects of operational conditions on the progress of oxy-fuel CFB combustion were investigated by means of a mathematical model for CFB oxy-fuel combustion together with experimental data from a 4 MWth oxy-fuel CFB, currently representing the largest oxy-fuel CFB combustion experiments in the literature. Modeled in-Furnace profiles for carbon monoxide (CO) and oxygen (O2) were compared to the corresponding measurements, yielding a general good agreement for both air- and oxy-fuel-fired conditions. The developed model was also used to investigate the effects of varying the inlet O2 concentration over a wider range than that applied in the experiments. The experimental results show that, for an equivalent inlet O2 concentration, the peak CO concentration is higher under oxy-fuel-fired conditions than under air-fired conditions. The model result shows that a higher inlet O2 concentration generates combustion of greater intensity up through the Furnace with a lower level of CO at the Furnace exit.

Zhongshan Li - One of the best experts on this subject based on the ideXlab platform.

  • biomass steam gasification in bubbling Fluidized Bed for higher h2 syngas cfd simulation with coarse grain model
    International Journal of Hydrogen Energy, 2019
    Co-Authors: Tian Qi, Guanyi Chen, Zhongshan Li, Hesameddin Fatehi, Zhiwei Wang
    Abstract:

    Abstract A comprehensive coarse grain model (CGM) is applied to simulation of biomass steam gasification in bubbling Fluidized Bed reactor. The CGM was evaluated by comparing the hydrodynamic behavior and heat transfer prediction with the results predicted using the discrete element method (DEM) and experimental data in a lab-scale Fluidized Bed Furnace. CGM shows good performance and the computational time is significantly shorter than the DEM approach. The CGM is used to study the effects of different operating temperature and steam/biomass (S/B) ratio on the gasification process and product gas composition. The results show that higher temperature enhances the production of CO, and higher S/B ratio improves the production of H2, while it suppresses the production of CO. For the main product H2, the minimum relative error of CGM in comparison with experiment is 1%, the maximum relative error is less than 4%. For the total gas yield and H2 gas yield, the maximum relative errors are less than 7%. The predicted concentration of different product gases is in good agreement with experimental data. CGM is shown to provide reliable prediction of the gasification process in Fluidized Bed Furnace with considerably reduced computational time.