The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform

Kunio Yoshikawa - One of the best experts on this subject based on the ideXlab platform.

  • co2 recycling biomass Gasification System for highly efficient and carbon negative power generation
    Applied Energy, 2015
    Co-Authors: Muhammad Aziz, Bayu Prabowo, Kentaro Umeki, Herri Susanto, Kunio Yoshikawa
    Abstract:

    This study explored the feasibility of biomass CO2 Gasification as an effective method for implementing the concept of a carbon-negative power System through bioenergy with carbon capturing and storage. A CO2-recycling biomass Gasification System was developed and examined using the thermal equilibrium model. Sensitivity analysis was performed by varying the gasifier temperature from 750 to 950°C, and the turbine inlet temperature (TIT) and turbine exit temperature (TET) of the gas turbine from 1000 to 1200°C and from 900 to 1000°C, respectively. The gasifier efficiency was increased by an increase in the CO2 recycling ratio with the more significant trend shown at the lower gasifier temperature. The turbine efficiency decreased as the CO2 recycling ratio to the gasifier increased over a certain limit, a ratio of 0.55 in most cases. A pressure ratio of 2.3 was optimum in terms of turbine efficiency. Under the examined conditions, the optimum conditions for gaining the highest System efficiency, 39.03%, were a recycling ratio of 0.55 and a TET and TIT of 1000 and 1200°C respectively. The proposed System had 7.57% higher efficiency and exhausted 299.15g CO2/kWh less CO2 emissions than conventional air Gasification. Combined with carbon capturing and storage, the System potentially generates carbon-negative power generation with intensity of around 1.55-kgCO2/kgwet-biomass and a maximum efficiency penalty of 6.89%.

  • characterization of tar content in the syngas produced in a downdraft type fixed bed Gasification System from dried sewage sludge
    Fuel, 2010
    Co-Authors: Thana Phuphuakrat, Tomoaki Namioka, Nimit Nipattummakul, Somrat Kerdsuwan, Kunio Yoshikawa
    Abstract:

    Abstract Tar yields in the syngas produced in a pilot-scale downdraft type fixed bed Gasification System from dried sewage sludge have been quantified and characterized to identify the effect of equivalence ratio (ER of 0.29–0.36). The increase of ER resulted in higher temperature of oxidation zone because air promoted the combustion reaction. High ER and high temperature also enhanced cracking and combustion of tar. Lower tar mass was observed while increasing ER. The change in tar composition with the change of ER was also observed by using the size exclusion chromatography (SEC). The SEC results showed that heavier molecular tar (in the molecular weight range of 300–500 u) formed whereas lighter molecular tar decreased under the higher ER conditions. Tar removal performances of the gas cleaning System (the venturi scrubbers and the sawdust adsorbers) were also investigated. The tar removal efficiency of the gas cleaning System depended on Gasification conditions, tar components and the amount of tar. Tar content in the syngas was reduced to 26–53% and 14–36% (by weight) at the exit of the scrubbers and sawdust adsorbers, respectively. By the action of this gas cleaning System, about 44% of light aromatic hydrocarbon tar was removed while no light PAH tar was detected at the exit of the gas cleaning System.

  • performance optimization of two staged Gasification System for woody biomass
    Fuel Processing Technology, 2007
    Co-Authors: Yin Wang, Kunio Yoshikawa, Tomoaki Namioka, Yoshirou Hashimoto
    Abstract:

    Abstract The performance of a small-scale two-staged Gasification System is reported. In this System wood chips are gasified with a fixed bed gasifier and then tar in the produced gas is reformed in a non-catalytic reformer, finally the production gas is used to generate electricity. In this System, the gasifying agents are high temperature air and steam supplied into the gasifier and the reformer. This paper reports on optimum Gasification air ratio (defined as the ratio of the oxygen mole supplied into the gasifier to the oxygen mole required for complete combustion of biomass), reforming air ratio (defined as the ratio of the oxygen mole supplied in the reformer to the oxygen mole required for the complete combustion of biomass) and steam ratio (defined as the ratio of the steam mole supplied into the gasifier to the carbon mole in biomass supplied into the gasifier) for producing required gas supplied into a dual-fueled diesel engine. The results showed that, under optimum conditions, the higher heating value of the reformed gas was 3.9 MJ/m3N; the cold gas efficiency (defined as the ratio of HHV reformed gas × reformed gas flow rate to HHV biomass × biomass feed rate) of the Gasification System was 66%, and the gross thermal efficiency of the overall System was 27%.

  • Development of a high-temperature air-blown Gasification System.
    Bioresource Technology, 2001
    Co-Authors: Carlson C.p. Pian, Kunio Yoshikawa
    Abstract:

    Current status of high-temperature air-blown Gasification technology development is reviewed. This advanced Gasification System utilizes preheated air to convert coal and waste-derived fuels into synthetic fuel gas and value-added byproducts. A series of demonstrated, independent technologies are combined to form the core of this Gasification System. A high-temperature, rapid devolatilization process is used to enhance the volatile yields from the fuel and to improve the Gasification efficiency. A high-temperature pebble bed filter is used to remove the slag and particulates from the synthetic fuel gas. Finally, a novel regenerative heater is used to supply the high-temperature air for the gasifier. Component development tests have shown that higher Gasification efficiencies can be obtained at more fuel-rich operating conditions when high-temperature air is used as the Gasification agent. Test results also demonstrated the flex-fuel capabilities of the gasifier design. Potential uses of this technology range from large-scale integrated Gasification power plants to small-scale waste-to-energy applications.

Ximin Zhang - One of the best experts on this subject based on the ideXlab platform.

  • hydrogen production by coal Gasification in supercritical water with a fluidized bed reactor
    International Journal of Hydrogen Energy, 2010
    Co-Authors: Youjun Lu, Bo Liao, Ximin Zhang
    Abstract:

    The technology of supercritical water Gasification of coal can converse coal to hydrogen-rich gaseous products effectively and cleanly. However, the slugging problem in the tubular reactor is the bottleneck of the development of continuous large-scale hydrogen production from coal. The reaction of coal Gasification in supercritical water was analyzed from the point of view of thermodynamics. A chemical equilibrium model based on Gibbs free energy minimization was adopted to predict the yield of gaseous products and their fractions. The Gasification reaction was calculated to be complete. A supercritical water Gasification System with a fluidized bed reactor was applied to investigate the Gasification of coal in supercritical water. 24 wt% coal-water-slurry was continuously transported and stably gasified without plugging problems; a hydrogen yield of 32.26 mol/kg was obtained and the hydrogen fraction was 69.78%. The effects of operational parameters upon the Gasification characteristics were investigated. The recycle of the liquid residual from the Gasification System was also studied.

Ibrahim Dincer - One of the best experts on this subject based on the ideXlab platform.

  • thermodynamic assessment of an integrated solar power tower and coal Gasification System for multi generation purposes
    Energy Conversion and Management, 2013
    Co-Authors: Murat Ozturk, Ibrahim Dincer
    Abstract:

    Abstract Multi-generation energy production Systems allow higher efficiency by integration of different Systems for recovering the highest possible exergy of the energy input. This paper concerns the thermodynamic assessment of a solar-based multi-generation System with coal Gasification, involving power, heating, cooling, hydrogen, oxygen and hot water production. The coal Gasification System is integrated with a solar power tower to utilize the concentrating solar energy. The clean syngas produced from the System is stored for the continuous power production. This multi-generation System has divided to the six sub-Systems. Energy and exergy efficiencies of each System are studied to show the System performance under the chosen conditions and also how to approach the ideal case. From the results, energy and exergy efficiencies of the sub-Systems change between 19.43–46.05% and 14.41–46.14%, respectively, and the multi-generation System has the maximum energy and exergy efficiencies as 54.04% and 57.72%, respectively. Additionally, parametric studies, including the thermodynamic performance of the multi-generation System components, are conducted by the change in some major design parameters, as variation of the environment temperature, compressor pressure ratio, nitrogen supply ratio for the combustion chamber and gas turbine entry temperature.

  • Performance assessment of hydrogen production from a solar-assisted biomass Gasification System
    International Journal of Hydrogen Energy, 2013
    Co-Authors: Yildiz Kalinci, Arif Hepbasli, Ibrahim Dincer
    Abstract:

    Abstract In this study, we investigate a solar-assisted biomass Gasification System for hydrogen production and assess its performance thermodynamically using actual literature data. We also analyze the entire System both energetically and exergetically and evaluate its performance through both energy and exergy efficiencies. Three feedstocks, namely beech charcoal, sewage sludge and fluff, are considered as samples in the same reactor. While energy efficiencies vary from 14.14% to 27.29%, exergy efficiencies change from 10.43% to 23.92%. We use a sustainability index (SI), as a function of exergy efficiency, to calculate the impacts on sustainable development and environment. This index changes from 1.12 to 1.31 due to intensive utilization of solar energy. Also, environmental impact of these Systems is evaluated through calculating the specific greenhouse gas (GHG) emissions. They are determined to be 17.97, 17.51 and 26.74 g CO2/MJ H2 for beech charcoal, sewage sludge and fluff, respectively.

  • energy and exergy analyses of an integrated sofc and coal Gasification System
    International Journal of Hydrogen Energy, 2012
    Co-Authors: Ibrahim Dincer, Rami Salah Elemam, G F Naterer
    Abstract:

    Abstract This paper examines an integrated Gasification and solid oxide fuel cell (SOFC) System with a gas turbine and steam cycle that uses heat recovery of the gas turbine exhaust. Energy and exergy analyses are performed with two different types of coal. For the two different cases, the energy efficiency of the overall System is 38.1% and 36.7%, while the exergy efficiency is 27% and 23.2%, respectively. The effects of changing the reference temperature on the exergy destruction and exergy efficiency of different components are also reported. A parametric study on the effects of changing the pressure ratio on the component performance is presented.

  • Solid Oxide Fuel Cell and Biomass Gasification Systems for Better Efficiency and Environmental Impact
    2010
    Co-Authors: C. Ozgur Colpan, Ibrahim Dincer, Thomas Grube, Feridun Hamdullahpur, Detlef Stolten
    Abstract:

    In this paper, a conventional biomass fueled power production System is compared with a SOFC and biomass Gasification System in terms of efficiency and greenhouse gas emissions. A heat transfer model of the SOFC and thermodynamic models for the other components of the Systems are used to find the performance assessment parameters of the Systems. These parameters are taken as electrical and exergetic efficiencies. In addition, specific greenhouse gas emissions are calculated to evaluate the impact of these Systems on the environment. The results show that the SOFC and biomass Gasification System has higher electrical and exergetic efficiencies and lower greenhouse gas emissions.

Mehmet Sinan Bilgili - One of the best experts on this subject based on the ideXlab platform.

  • the risk analysis by failure mode and effect analysis fmea and fuzzy fmea of supercritical water Gasification System used in the sewage sludge treatment
    Journal of environmental chemical engineering, 2017
    Co-Authors: Elanur Adar, Mahir Ince, Buket Karatop, Mehmet Sinan Bilgili
    Abstract:

    Abstract Supercritical water Gasification (SCWG) System is a hydrothermal conversion process used for the treatment of wastes with organic and toxic content and it is an especially promising technology for biomass with high water content such as sewage sludge. The interest in this technology is on a paramount increase because of both economic and environmental reasons. However, this System is marked by certain problems even though it has significant advantages. The aim of this study is to determine the problems that occur during the commissioning and operation of a continuously operated, laboratory-scale supercritical water Gasification System and to identify their reasons and effects. For this purpose, cause-and-effect diagram, classical failure mode and effect analysis and fuzzy failure mode and effects analysis were carried out. As a result of the analyses performed, it has been concluded that the most important problems are plugging, corrosion, reactor design and incompatible material selection. As for the most important risks that occur in SCWG, they include explosion, injury, odor and noise. It has been seen that conducting a risk analysis of the SCWG System is important for job safety and sound operation.

Tomoaki Namioka - One of the best experts on this subject based on the ideXlab platform.

  • characterization of tar content in the syngas produced in a downdraft type fixed bed Gasification System from dried sewage sludge
    Fuel, 2010
    Co-Authors: Thana Phuphuakrat, Tomoaki Namioka, Nimit Nipattummakul, Somrat Kerdsuwan, Kunio Yoshikawa
    Abstract:

    Abstract Tar yields in the syngas produced in a pilot-scale downdraft type fixed bed Gasification System from dried sewage sludge have been quantified and characterized to identify the effect of equivalence ratio (ER of 0.29–0.36). The increase of ER resulted in higher temperature of oxidation zone because air promoted the combustion reaction. High ER and high temperature also enhanced cracking and combustion of tar. Lower tar mass was observed while increasing ER. The change in tar composition with the change of ER was also observed by using the size exclusion chromatography (SEC). The SEC results showed that heavier molecular tar (in the molecular weight range of 300–500 u) formed whereas lighter molecular tar decreased under the higher ER conditions. Tar removal performances of the gas cleaning System (the venturi scrubbers and the sawdust adsorbers) were also investigated. The tar removal efficiency of the gas cleaning System depended on Gasification conditions, tar components and the amount of tar. Tar content in the syngas was reduced to 26–53% and 14–36% (by weight) at the exit of the scrubbers and sawdust adsorbers, respectively. By the action of this gas cleaning System, about 44% of light aromatic hydrocarbon tar was removed while no light PAH tar was detected at the exit of the gas cleaning System.

  • performance optimization of two staged Gasification System for woody biomass
    Fuel Processing Technology, 2007
    Co-Authors: Yin Wang, Kunio Yoshikawa, Tomoaki Namioka, Yoshirou Hashimoto
    Abstract:

    Abstract The performance of a small-scale two-staged Gasification System is reported. In this System wood chips are gasified with a fixed bed gasifier and then tar in the produced gas is reformed in a non-catalytic reformer, finally the production gas is used to generate electricity. In this System, the gasifying agents are high temperature air and steam supplied into the gasifier and the reformer. This paper reports on optimum Gasification air ratio (defined as the ratio of the oxygen mole supplied into the gasifier to the oxygen mole required for complete combustion of biomass), reforming air ratio (defined as the ratio of the oxygen mole supplied in the reformer to the oxygen mole required for the complete combustion of biomass) and steam ratio (defined as the ratio of the steam mole supplied into the gasifier to the carbon mole in biomass supplied into the gasifier) for producing required gas supplied into a dual-fueled diesel engine. The results showed that, under optimum conditions, the higher heating value of the reformed gas was 3.9 MJ/m3N; the cold gas efficiency (defined as the ratio of HHV reformed gas × reformed gas flow rate to HHV biomass × biomass feed rate) of the Gasification System was 66%, and the gross thermal efficiency of the overall System was 27%.