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Lowering Gasifier Tars and Particulates Using Heated Dololmite Catalyst and a Particulate Filter  [PDF]
Christopher O. Akudo, Beatrice G. Terigar, Chandra S. Theegala
Smart Grid and Renewable Energy (SGRE) , 2012, DOI: 10.4236/sgre.2012.31008
Abstract: For this study, a fixed-bed, down-draft gasifier was designed to investigate the effect of a dolomite catalytic bedon tar removal. Pine pellets and wood chips (cypress) were used to produce syngas from the down-draft gasifier. For the gas conditioning, a combination of a heated dolomite (bed temperature at 850?C for catalytic cracking of tars) and a particulate filter (for particulate removal) was used. Investigation of temperature effects on dolomite activity between 650?C and 950 C bed temperatures, showed optimum catalytic efficiency at approximately 850?C. At the optimum conditions, gravimetric tar and particulate concentrations in syngas produced from pine pellets were 0.85 g/Nm3 (±0.16) and 4.75 g/Nm3 (±0.07), respectively before gas conditioning, and 0.09 g/Nm3 (±0.02) and 2.01 g/Nm3 (±0.13), respectively after gas conditioning. Syngas from wood chips contained 1.63 g/Nm3 (±0.45) and 3.84 g/Nm3 (±1.16) of tars and particulates, respectively before gas cleaning and 0.19 g/Nm3 (±0.02) and 2.27 g/Nm3 (±0.27) tars and particulates, respectively after gas conditioning. The combustible portion of the gas constituted carbon monoxide (12% - 14%), hydrogen (11% - 12%), and methane (~2%). These results suggest that syngas produced from gasification of pine pellets and wood chips in a down-draft biomass gasifier can be effectively cleaned using a heated catalyst bed and a particulate filter. However, the benefits of gas conditioning will be offset by the need to maintain a heated catalyst bed for tar cracking.
Thermal Gasification of Rice Husks from Rice Growing Areas in Mwea, Embu County, Kenya  [PDF]
Paul Njogu, Robert Kinyua, Purity Muthoni, Yusuyuki Nemoto
Smart Grid and Renewable Energy (SGRE) , 2015, DOI: 10.4236/sgre.2015.65010
Abstract: Thermal gasification of biomass provides a potential renewable energy resource in rural areas in Kenya. Rice husks are a key byproduct of rice production that are not considered of economic value to millers. Rice husks obtained from Mwea, Embu County, Kenya were converted into syngas using a locally assembled modified updraft gasifier. The syngas production was produced at temperatures between 450°C and 750°C with injection of limited supply of air and purified using series of gas cleaning and cooling devices. Proximate analysis shows that rice husks have a mean content of 21.9% ± 0.3% ash, 9.5% ± 3.3% moisture, 78.8% ± 0.3% volatiles and 91.8% ± 1.3% total solids. Carbonized rice husks have mean contents of 37.8% ± 1.2% ash, 3.1% ± 0.4% moisture, 62.3% ± 1.2% volatiles and 96.5% ± 0.4% total solids. The study shows that feedstock is consumed at a rate of 25 - 32 Kg/Hr with gas generation rate of 7.76 - 7.78 m3/hr; this translates to a gas yield of 0.31 - 0.35 m3/Kg. Process water was re-circulated at a rate of 2.2 m3/hr within the plant. The total electricity consumption per hour was 1.1 - 1.3 kWh. Carbon monoxide (CO) and temperature were monitored in the working area to assess the safety of the workers and were found to be in the range of 35 - 50 ppm and 24°C - 29.5°C respectively. The two were found to be within safe limits; however, the CO concentrations increased when leakages occurred. Syngas was found to be composed of 16.5% - 17.55% CO, 14.5% - 16.1% CO2, 4.1% - 4.5% H2, 6.8% - 7.2% CH4 and 17.9% - 45.7% N2 among others. The gas was used for direct heating applications and to run modified petrol engines. Carbonized husks were used to make energy briquettes and partly applied to the rice growing pads to improve soil properties. The technology provides energy solutions and aids in the abatement of climate change mitigation and abatement since it provides a permanent carbon sink. The technology provides a value addition chain for rice growers.
An Investigation on Performance of a Horizontal Entrained Flow Gasifier  [PDF]
Isack A. Legonda
Journal of Power and Energy Engineering (JPEE) , 2018, DOI: 10.4236/jpee.2018.63003
Abstract: A novel study on biomassair gasification using a horizontal entrained-flow gasifier has been conducted. The use of a horizontal entrained-flow gasifier reactor was employed to assess the effect of the gasifier reactor orientation on the gasification process. The gasification experiments were conducted at 800℃ and equivalence ratio of 0.23 while maintaining gas hourly space velocity (GHSV) of 8000 h-1. Preparation and characterisation of wood powder were performed using classical methods. The research findings showed that maximum fuel conversion and cold gas efficiency using a horizontal entrained-flow gasifier were 99% and 70% respectively compared to 91% and 62% respectively of the vertical design. Moreover, the gasifier length can also be reduced from the common 1000 - 2000 mm to 500 mm. In general, the results of this study suggest that there exists a sensitivity to the gasifier orientation on the overall gasification process.
Structured Perovskite-Based Oxides: Use in the Combined Methane Reforming  [PDF]
Adriana García, Norymar Becerra, Luis García, Ini Ojeda, Estefanía López, Carmen M. López, Mireya R. Goldwasser
Advances in Chemical Engineering and Science (ACES) , 2011, DOI: 10.4236/aces.2011.14025
Abstract: The behavior of metallic structured perovskite-based catalysts was evaluated in the combined methane reforming reaction with CO2-O2. The reaction conditions were established by varying the reaction temperature and reactor input composition in the range of 650 to 850℃ and CH4/CO2 ratio 1 to 5, respectively. The results of the catalytic tests at 750℃ showed a positive effect of the metallic structure, producing higher conversions and H2/CO ratios in the products compare to that obtained with the powder catalyst.
Yttria Promoted Nickel Nanowire Catalyst for the Partial Oxidation of Methane to Synthesis Gas  [PDF]
Xuebin Hong, Bingbing Li, Cong Zhang
Advances in Materials Physics and Chemistry (AMPC) , 2012, DOI: 10.4236/ampc.2012.24B054
Abstract: A yttria promoted nickel nanowire catalyst was prepared by a hard templating method, and characterized by transmission electron microscopy (TEM) and N2 physical adsorption. The catalytic properties of the yttria promoted nanowire catalyst in the partial oxidation of methane to syngas were compared with a metallic Ni catalyst which was prepared with nickel sponge. The characterization results showed that the yttria promoted nickel nanowire catalyst had high specific surface area and there was more NiO phase in the nickel nanowire catalyst than in the metallic Ni catalyst. The reaction results showed that the yttria promoted nickel nanowire catalyst had high CH4 conversion and selectivities to H2 and CO.
On Gasification of Different Tropical Plant-based Biomass Materials
Shaharin A. Sulaiman,Muhammad F. Karim,M. Nazmi,Z. Moni
Asian Journal of Scientific Research , 2013,
Abstract: In this study, the characteristics of synthetic gases derived from different plant-based biomass feedstocks are studied using a downdraft gasifier. The biomass materials are oil palm frond, mangrove wood, sugarcane bagasse and coconut husk. Understanding of these characteristics would lead to proper judgment on the suitability of co-gasification of the different biomass materials. The temperature profiles in the gasifier are recorded and the syngas compositions are estimated. It is found that the mangrove wood has the highest energy content (22,292 J g-1) at 11% moisture content (wet basis). It is also observed that mangrove wood has nearly similar properties to that of oil palm fronds as compared to sugarcane bagasse and coconut husks.
Mathematical Modelling of Biomass Gasification in a Circulating Fluidized Bed CFB Reactor  [PDF]
Roberto Capata, Mario Di Veroli
Journal of Sustainable Bioenergy Systems (JSBS) , 2012, DOI: 10.4236/jsbs.2012.24022
Abstract: The scope of the present paper is to investigate the suitability of a mathematical model for Circulating Fluidized Bed (CFB) coal combustion (developed by the International Energy Agency), to predict and simulate the performance of the 100 kWth CFB for air-blown biomass gasification. The development of a mathematical model allows to simulate the operative conditions during biomass gasification, control the quality of the synthesis gas and improve the gasifier design. The geometrical, mechanical, hydro dynamical and thermo chemical features were introduced in the model by properly setting the input file and, some changes have been made in the code to assure the final convergence. A sensitivity analysis has been performed to study the variation in the input parameters of the program, and it has been finally verified by comparing the results with the empirical data collected during coal and wood combustion tests. The program, in the same case, could not successfully run; probably depending on wood char density value. For these reason the influence of char density will be investigated. The model predicts the development of tar and other hydrocarbons, valuating the agreement between the measured and calculated efficiency. A further development, to consider solid biomass, with a certain volatile percentages (20% - 40%), as a fuel has been previewed and analyzed. Finally some investigations have been carried out to provide some useful indications for future developments of the code, in the biomass gasification modelling
Review on Innovative Catalytic Reforming of Natural Gas to Syngas  [PDF]
Salwa A. Ghoneim, Radwa A. El-Salamony, Seham A. El-Temtamy
World Journal of Engineering and Technology (WJET) , 2016, DOI: 10.4236/wjet.2016.41011
Abstract: Decreasing supplies of high quality crude oil and increasing demand for high quality distillates have motivated the interest in converting natural gas to liquid fuels, especially with the present boom in natural gas proven reserves. Nevertheless, one major issue is the curtailment of costs incurred in producing synthesis gas from natural gas, which account for approximately 60% of the costs used in producing liquid fuels. While there are three main routes to convert natural gas to syngas: steam reforming (SMR), partial Oxidation (POX) and auto-thermal reforming (ATR). Significant new developments and improvements in these technologies, established innovative processes to minimize greenhouse gases emission, minimize energy consumption, enhance syngas processes, adjust the desired H2/CO ratio and change the baseline economics. This article reviews the state of the art for the reforming of natural gas to synthesis gas taking into consideration all the new innovations in both processes and catalysis.
Reformado de metano con CO2 sobre óxidos mixtos Ni-Mg-Al-Ce derivados de hidrotalcitas: Efecto de la relación Mg/Ni
Daza,Carlos Enrique; Mondragón,Fanor; Moreno,Sonia; Molina,Rafael;
Revista Facultad de Ingeniería Universidad de Antioquia , 2011,
Abstract: ni-ce/mg-al catalysts were obtained by means of the hydrotalcite reconstruction method in the presence of [ce(edta)]- complex. the effect of the mg/ni ratio was studied when the mixed oxide was reconstructed with 3 wt. % ce loadings. the materials were characterized by x-ray diffraction (xrd), thermal-gravimetric analysis (tga), temperature-programmed reduction (tpr-h2), temperature-programmed oxidation (tpo) and co2 temperature-programmed desorption (tpd-co2). the reduced catalysts were tested in co2 reforming of methane under two operation regimens: i) reaction between 500 to 800°c using volumetric ratios of ch4/co2/ ar=5/5/40 and, ii) isothermal reaction at 700°c using volumetric ratios of ch4/co2=18/22 without diluent gas. the solids showed strong basic characteristics and high ni-surface interactions which determined their catalytic performance. catalysts with mg/ni molar ratios of 2 and 4 showed high ch4 and co2 conversions with h2/co molar ratios between 0.7 and 1.1 without coke formation under severe isothermal reaction conditions. the yields and activities were higher when reduction increased.
Simulación de un Sistema de Gasificación Integrado a un Ciclo Combinado
Martínez,Eliseo; Vicente,William; Salinas-Vázquez,Martín;
Información tecnológica , 2006, DOI: 10.4067/S0718-07642006000600021
Abstract: a numerical model is used for simulating an integrated gasifier combined cycle system. the model considers a general approach for each piece of equipment in the system and the chemical equilibrium for the composition of the syngas. coke is used as the fuel, and is described by the form cmhnnssr. mass and energy balances are solved using the gauss-jordan method. the results were compared with data obtained from plants in operation. the comparative analysis showed that the evaluation methodology for the integrated gasifier combined cycle system was acceptable.
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