Yuegui Zhou

Study on performance of the ball packed-bed regenerator: experiments and simulation

Abstract The performances of the ball packed-bed regenerator were investigated experimentally and numerically by the authors of the paper. In the study for resistance characteristics of the regenerator, based on the experimental data, a revised Erguns equation with the coefficients k 1 =203 and k 2 =1.95 was achieved for the randomly packed bed of uniform spheres. The thermal characteristics of the regenerator was studied by a 1-D, transient numerical model. Emphasis was put on the effect of variations of fuel on the exit flue gas temperature and the heat recovery. This study indicates that not all fuels are applicable for the regenerative furnace if single preheating is used. For the fuels with low- or medium-caloric value, double preheating should be taken while for the fuels with high-caloric value, both single and double preheating can be used.

The effect of hydrogen peroxide solution on SO2 removal in the semidry flue gas desulfurization process

The present study attempts to use hydrogen peroxide solution to humidify Ca(OH)(2) particles to enhance the absorption of SO(2) to achieve higher removal efficiency and to solve the valuable reuse of the reaction product in the semidry flue gas desulfurization (FGD) process. Experiments were carried out to examine the effect of various operating parameters including hydrogen peroxide solution concentration, Ca/S molar ratio and approach to adiabatic saturation temperature on SO(2) removal efficiency in a laboratory scale spray reactor. The product samples were analyzed to obtain semi-quantitative measures of mineralogical composition by X-ray diffraction (XRD) with reference intensity ratio (RIR) method and the morphology of the samples was examined by scanning electron microscope (SEM). Compared with spraying water to humidify Ca(OH)(2), SO(2) removal efficiency was improved significantly by spraying hydrogen peroxide solution of 1-3 wt.% to humidify Ca(OH)(2) because hydrogen peroxide solution enhanced the dissolution and absorption rate of SO(2). Moreover, XRD and SEM analyses show that the desulfurization products contain less amount of unreacted Ca(OH)(2) and more amount of stable calcium sulfate with increasing hydrogen peroxide solution concentration. Thus, the process mechanism of the enhanced absorption of SO(2) by spraying hydrogen peroxide solution to humidify Ca(OH)(2) was elucidated on the basis of the experimental results.

Ignition and Combustion Characteristics of Different Rank Coals in O2/CO2 Environments

Previous works on flame stability and stand-off distance under oxy-coal combustion conditions has been conducted with a co-axial turbulent diffusion burner for different rank coals in a 100 kW pulverized coal test rig at the University of Utah. The pilot-scale results indicate that oxygen partial pressure and coal compositions have a significant effect on the ignition and flame stability of coal particles in the oxy-coal combustion. The aim of the present paper is to investigate the ignition and combustion characteristics of three different rank coals at variable oxygen partial pressures in O2/N2 and O2/CO2 environments by Thermo-gravimetric Analyzer (TGA). The experimental results reveal the significant difference of the devolatilization, ignition and combustion properties between three rank coals in O2/CO2 environments. It could provide fundamental understanding on pulverized coal combustion in O2/CO2 environments and elucidate the effect of coal compositions on the ignition and flame stability in pilot-scale oxy-coal combustion.

Numerical Optimization of the Collision Humidification Processin the Multifluid Alkaline Spray Generator for a 75t/h Incinerator Flue Gas Cleaning System

Three-dimensional computational fluid dynamics mathematical model is used to simulate gas-droplet-particle multiphase flow and the collision humidification between droplets and sorbent particles in a multifluid alkaline spray generator for a 75t/h incinerator flue gas cleaning system. In this model, the motions of discrete phases are tracked simultaneously by stochastic trajectory approach, and a probability model of droplets catching particles is presented to judge whether the particles are caught or not. The main structure and operation parameters are optimized to give valuable reference to the design and operation of the FGD process. The results show that to decrease flue gas flow rate can improve the collision humidification efficiency between droplets and sorbent particles but it maybe result in the recirculation flow. The humidification efficiency can reach 78.5% and there is no recirculation zone in the alkaline spray generator when the ratio of flue gas mass flow rate to spray water mass flow rate is 6.7. There is an optimal droplet diameter ranged from 125µm to 150µm corresponding to maximum humidification efficiency in this paper. The opti particle injection location is the internal annular of the entrance cross-section near to the spray jet.