This paper describes an experimental study on N2O and NO x emission from char combustion. Experiments have been carried out in a fixed bed reactor in the temperature range of 973−1323 K. Oxygen concentrations for combustion, temperature, and char type have been found to have strong effects on both N2O and NO x emissions. With an increasing temperature, N2O reaches a peak at 1073 K and then decreases with temperature. At the same time NO x remains nearly the same. When oxygen concentration increases, the concentration of N2O increases and NO x first increases and then decreases. The char with higher nitrogen content emits more N2O, indicating that nitrogen oxides come from char-N. When NO is included in the inlet gases, much more N2O is produced from char combustion. This suggests that the reaction of NO + O2 + char is the main pathway for N2O formation. Another pathway, i.e., the homogeneous oxidation of HCN from the gasfication of char, seems to be important as well.

A Circulating Fluidized Bed Combustor (CFBC) is a highly efficient combustor. It can handle various types of solid fuels such as coal, biomass or agricultural wastes. Coal and biomass have been used as fuel to generate heat for a boiler in many industries. To predict the proper amount of mixed fuel and to reduce the emission from coal burning, a rigorous mathematical model for the CFBC is needed. This paper describes the CFBC model developed as additional subroutines working with ASPEN PLUS version 11.1. The model was divided into three parts: reaction, hydrodynamic, and gas emission. In the first part, the reactions in the combustor were represented by a Continuous Stirred Tank Reactor (CSTR) module. The module was modified by adding the shrinking core model for calculating the size and the weight fraction of particles in each region. In the second part, the hydrodynamics in CFBC were divided into two regions: a lower region with one interval, and an upper region with three intervals. In each region the characteristics, such as the height of the bed, void, and volume, were calculated and sent to CSTR module for adjusting reaction rates in the regions. In the third part, gas emission models were used to calculate the kinetic rates of NO, N 2 O and the conversion of SO 2 to predict the emission to the environment.

In recent years, circulating fluidized beds (CFBs) have been extensively employed in a variety of industrial applications related to coal combustion and gasification, solid waste incineration, catalytic cracking of oil, and so on. To accomplish successful and reliable operation of CFBs, a number of in- Detailed researches in this direction will considerably help in the optimum and economic designs of CFB boilers. To aid in this direction, we have measured the three-dimensional particle velocities in a square-section CFB cold model under certain operating conditions at ambient temperature and pressure. Particle turbulent intensities and bed cross-sectional averaged voidage along its height are also measured. A majority of the investigations have been conducted in circular cross-section CFBs, but industrial preference is for a square cross-section boiler, and hence we have adopted this configuration in our present work. Our measurements, while confirming the coreannulus flow structure for CFBs, also provide a more comprehensive microscopic detail of particle velocities in the two regions, in addition to providing a basis for particle aggregation. Experimental Apparatus and ResultsThe schematic of the CFB employed in the present work is shown in Figure 1. The riser section is 3 m long and has a square cross-section, 222 mm by 222 mm. Seventeen pressure taps (13) are installed along the metal bed wall starting from a height of 250 mm' above the air distributor plate (3) and up

We present a novel approach called Global Color Composition (GCC) to improve the visual effect of large image show on curved screen multi-projector display system. Instead of traditional approach only blend overlapped area, our algorithm utilize the global gradient-domain information to get better effect, and as an optimizing of the algorithm to reduced time and memory, we utilize the patches border pixels to construct the passion equation. The solver of this passion equation is result image we desired, which can be solving on parallel GPU threads. Experiment results are given to illustrate the effect of our approach.

Performances of Ag-SnO2 electrical contact materials can be strongly affected by the microstructure. In this work, Ag-SnO2 composite powders were synthesized by chemical reductive precipitation method. During the precipitation process, Ag particle was deposited onto the surface of SnO2 particle with the assistance of citric acid. The microstructure and properties were analyzed for the prepared Ag-SnO2 electrical contact materials. Our research reveals that the particle size of SnO2 has significant influence on the morphology of the Ag-SnO2 composite powders, and therefore on the microstructure and physical properties of the electrical contact materials. With the decrease of particle size of SnO2, hardness of the Ag-SnO2 electrical contact materials increases, while electrical conductivity decreases.