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Air supply is one of the most important factors that influence the combustion of the volatile and carbon in a biomass fired boiler. For many biomass power generation plants, there is insufficient measure to assure the proper air supply. In this study, computational fluid dynamics (CFD) modeling of a double-grate biomass fired boiler was carried out. The three-dimensional Reynolds averaged Nervier-stokes...
Gasification based biomass co-firing was an attractive technology for biomass utilization. Compared to directly co-firing of biomass and coal, it might: (1) avoid feeding biomass into boiler, (2) reduce boiler fouling and corrosion problem, and (3) avoid altering ash characteristics. In this paper, CFD modeling of product gas (from biomass gasification) and coal co-firing in a 600MW tangential PC...
A numerical model of the flow field of a 48t/h grate-fired boiler was presented in this paper. The air distributions in the furnace under different air supply ratio were considered in order to get the optimum air ratio. The three-dimensional Reynolds averaged Nervier-stokes equation with the Standard k-epsilon Model was solved. The result showed that the airflow ratio played a significant role on...
Chemical looping combustion (CLC) was a promising combustion technology with inherent separation of CO2. In this paper, thermodynamic equilibrium approach was used to investigate the reactions between CO or biomass gas and oxygen carrier Fe2O3, and experiments were carried out in a laboratory fluidized bed reactor. The results showed that when temperature was below 1000 K, the carbon deposition on...
The reduction of N2O by adding biomass gas as reburning fuel is studied on a small-scale vertical reactor tube and experimental results are analyzed using the theory of chemical kinetics. The result showed that for the flue gas containing a certain concentration of N2O, when the biomass gas contained H2, CH4, CO and CO2 was used, the reburning fuel ratio should be more than 1.4%. The decomposition...
A non-stoichiometric equilibrium model was proposed to predict the performance of a biomass gasifier in this study. The model had produced satisfying results for product gas composition and lower heating value (LHV) prediction in air gasifier in comparison with data from literature. Effects of the operational parameters and fuel type (H/C and O/C) on the product gas were investigated.
Chemical-looping combustion (CLC) has been suggested as an energy efficient method for CO2 capture without extra energy cost for the separation of CO2. In CLC oxygen is transferred from the combustion air to fuel by means of an oxygen carrier. The fuel and the combustion air are never mixed, and the combustion products (CO2 and steam) are kept separate from the flue gas. After condensation of the...
Gasification based biomass co-firing was an attractive technology for utilizing biomass as an additional fuel in utility boilers. Compared to directly co-firing biomass and coal, it showed following benefits: (1) avoiding biomass delivery into the boiler, (2) reduced boiler slagging, (3) avoiding altered ash characteristics. In co-firing demonstration project, higher percentage of biomass gas for...
Ni/γ-Al2O3-550 and Ni/γ-Al2O3-800 catalysts (calcined at 550°C and 800°C in the catalyst preparation) were prepared with a impregnation method. Steam reforming of acetic acid as a model compound of bio-oil for hydrogen production had been investigated on the catalysts. The fresh catalysts were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR-H2) and specific surface...
The pyrolysis of straw was one of the important ways for biomass utilization. Chemical structure of straw lignin had great impact on the decomposition process of straw. In this paper, lignin molecule was modeled with an average structure method and optimized with Density Functional Theory (DFT). The most stable conformations of structural units and structural model of straw lignin were obtained by...
The reduction machinism and kinetics characteristic of the reaction of carbon oxide (CO) and Nnitrous oxide (N2O), which contained the influence of reaction time on the reactants and products, were studied in the paper. The radical reaction of CO and N2O was assumped in a ideal reactor with a high temperature and a constant pressure, and was analyzed with chemical reaction kinetics theory. The result...
Based on Aspen Plus, a computer simulation model for sludge gasification was developed. The influences of moisture content in sludge, gasification pressure and equivalence ratio(ER) were considered. The results showed that, the producer gas were mainly CO, H2, CO2 and H2O with little H2S, CH4, while SO2 and N2 were almost none; with the increase in sludge moisture content, ER should be increased in...
The experimental research on removing N2O with biomass gas was carried out in a small-fluidized bed reactor tube. The decomposition rate of N2O and the production rate of NO impacted by reaction temperature, residence time, reburning position, rate of fuel, initial oxygen content of flue gas and the height of material bed were researched. The results showed that the decomposition rate of N2O was more...
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