Advanced Materials Research Vols. 354-355

Abstract: Reburning is effective to control NO emission. The paper presents a short review on recent research on catalysis reduction of NO and HCN/NH₃ by some metal and their oxides during reburning. The major difficulties that limit NO reduction efficiency by reburning involve the re-oxidation of the intermediate products during reburning, HCN/NH₃ and char nitrogen to NO. So far, results showed that Fe₂O₃ could reduce the formation of HCN/NH₃ after reburning and metallic iron could directly reduce NO to N₂. Temperature and co-existing gases influenced the catalysis performance of Fe and its oxides. Detailed mechanism and kinetics of the reactions should be further investigated.

Abstract: A combustion and heat transfer model in oxy-fired CFBB was set. Particle diameter, voidage of the bed ,etc, was analyzed with 30%, 50%, and 70% oxygen. Take a 300MW CFBB for example, the heat transfer characteristics in furnace were numerical simulated. In the sparse zone, heat transfer coefficient is proportional to oxygen concentration at the same voidage of the bed; under the same operation condition, the heat transfer coefficient in CFB increases with the voidage of the bed at first, then it decreases. It was found the heat transfer capability decrease due to the higher concentration of oxygen. It is necessary to set an external heat exchanger to keep a normal combustion

Abstract: The way of resonance ground of arc suppression coils at neutral point can extinct the grounding arc effectively. Both preset mode and post-set mode have their drawbacks. Thus,a new kind of arc suppression coil combined with coarse and fine adjustment was designed. The coarse adjustment is using turns adjustable arc suppression coils, while the fine adjustment coil is using magnetic bias style. And a control system based on single chip computer was designed to accomplish the auto-turning of arc suppression coils. And the MATLAB simulation on automatic tracing compensations of arc suppression coils proved the feasibility of this scheme.

Abstract: The combustion rates of carbon particle in pressurized oxygen-enriched environment were studied. The combustion rates of different diameter carbon particles were calculated in atmospheric as well as pressurized oxygen-enriched conditions. The effects of pressure and particle size on combustion rate of carbon particle were investigated. It shows that the combustion rate of carbon particle rise with the increase of the pressures in pressurized oxygen-enriched and pressurized air conditions. But, the combustion rate of carbon particle change little at higher pressure. When particle size increased from 50μm to 100μm，the combustion rate of carbon particle rising. When the particle size increased to 150μm, the combustion rate of carbon particle changed little.

Abstract: Use the method of Numerical simulation to different operating parameters and structural parameters of blast air swirl burner . On the basis of it, several evaluation indicators of swirl burners were proposed.

Abstract: An experimental study has been carried out to investigate the heat transfer and pressure drop characteristics of flat tube heat exchangers with plain, wavy, louvered and offset strip fin surfaces. Results are presented as plots of Colburn j factor and friction factor f against Reynolds in the range of 600-6500. Additionally, the dimensional heat transfer coefficient and pressure drop are presented as a function of frontal air velocity. Finally, two comparison methods are adopted to evaluate the air side performance of the plain fin, wavy fin, louvered fin and offset strip fin surface. The results show that the offset strip fin has the best performance of heat transfer enhancement.

Abstract: Establishes 3d numerical simulation model of water side and air side for ribbon-tubular radiator, studies effect of air velocity on air side heat transfer capacity and drag characteristics by using CFD method, based on double side 3d simulation result, and then calculates the import and export water temperature of the high low temperature radiator group with procedure. The calculated water temperatures are coinciding with experimental data. Then analyzes the influence rule of different wave combinations to the radiator group performance by the method of simulation and procedure calculation, the result is reference theory for the structure optimization and matching of the radiator group.

Abstract: This paper introduces a novel matrix method for calculating the efficiency of a thermal power plant unit with double reheat cycles. The structure of this matrix method has a mapping relationship with the thermodynamic system of the thermal power plant unit with double reheat cycles, and it can simplify the thermal economic analysis of the double reheat cycles units. An example is given to illustrate the validity of the method.

Abstract: The optimizing design approach of direct air-cooled system was described in detail in this paper. Based on the approach, the wind speed, ambient temperature and heat transfer area of air-cooled condenser were considered to meet the design parameters and the rated power. The optimizing results and economic analysis were discussed.

Abstract: Circulating fluidized bed (CFB) combustion techniques have been widely used in China. In order to improve CFB boiler performance it is necessary to study on microstructures of fly-ash. With the help of nitrogen adsorption instrument and scanning electron microscopy, the pore structure of fly-ash in circulating fluidized bed boilers are studied by nitrogen adsorption/desorption isotherms of fly-ash, hysteresis loop and pore distribution. The results indicated that different particle sizes of fly-ash in CFB boilers are of similar nitrogen adsorption isotherms, pore types and the pore size distribution, and the most probable pore radius of fly-ash is about 2nm. Adsorption isotherms of fly-ash is the second type, and the macro-porous and meso-porous types are tapered hole, parallel plate slit hole and the ink bottle shape hole. And meso-pore in proportion is the largest. Micro-pores are not discovered in fly-ash from CFB boilers.