Advanced Materials Research Vols. 781-784

Abstract: Bias flow is an important parameter in a flotation process of packed column. An experiment related to P₂O₅ recovery of phosphate rock was designed to study the effect of bias flow on the flotation separation efficiency by a direct-reverse flotation circuit of packed flotation column. The results have showed that the recovery of P₂O₅ is high during the combination of the direct-reverse flotation circuit. The grade and yield of P₂O₅ can reach to 32.77% and 82.64% respectively, under the condition of the range of-0.005~0 cms^-1 of bias flow, 0.013~0.020 cms^-1 of the wash water flow rate in the direct flotation column, and the range of 0.006~0.009 cms^-1 of bias flow, 0.027~0.035 cms^-1 of wash water flow rate in the reverse column.

Abstract: At present, the fire extinguishers equipped on China's warship cannot meet the requirements of the extinguishing of a ship fire, due to its special working environment. Focusing on this problem, this paper analyzes the deficiency of fire extinguisher equipped on warship currently. A comparison of U.S. military, European and Chinese standards of fire extinguisher has been done, respectively from aspects of the high and low temperature resistance, corrosion resistance, vibration resistance, shock resistance and the jet distance and the pressure resistance. The advantages and disadvantages of each standard have been analyzed. The necessity of the establishment of a marine fire extinguisher standard for our country has been probed. In the end, some suggestions have been put forward.

Abstract: The novel geometrical configuration of embedded planetary-screws is proposed in the paper. The corresponding numerical simulation and the experimental investigation are carried out to characterize the mixing performance. Adopting commercial software FLUENT, the simplified physical model is presented with the boundary conditions imposed by UDF codes which are developed by us. Compared with the traditional single screw extruder, the flow and mixing are primarily investigated by using particle tracking technology. The sensitivity to initial positions is found in the novel screw configuration, which is caused by the periodic perturbation of planetary-screws. In contrast, the traditional laminar mixing occurs in single screw extruders. Compared with the traditional twin screw extruder, the experimental characterization of filled system of adding active nanometer CaCO3 into LLDPE matrix is conducted. No obvious difference in dispersion of CaCO3 is found when the extrusion samples are observed through scanning electron microscopy (SEM), on the condition that the both extrusion outputs are equal. The shear rate in the novel screw configuration is relatively smaller, and the extrusion characteristic is more excellent.

Abstract: The flow field produced by a plate propeller in a fully baffled flat bottomed cylindrical stirred tank with the diameter of 300 mm was measured using phase doppler particle analyzer. The radial distributions of the time-averaged, fluctuation velocity and turbulent kinetic energy were analyzed. The effects of off-bottom clearance and baffle on the flow field were investigated. The results showed that the fluctuation velocity and turbulent kinetic energy increased with increasing off-bottom clearance in the impeller region; meanwhile, the maximum values of the time-averaged and fluctuation velocity moved to the center of the stirred tank. The maximum axial velocity decreased with increasing off-bottom clearance in the bulk flow. The turbulent kinetic energy was higher in the impeller region. The maximum value of the turbulent kinetic energy increased with increasing off-bottom clearance and occurred near the end of the impeller. The baffle hindered the tangential velocity and exerted strong influence on the turbulent kinetic energy. The flow field in front of the baffle reflected the distribution of the turbulent kinetic energy in the impeller region.

Abstract: Based on the Rayleigh-Plesset-Keller-Kolodner equation, the dynamics of single bubble is calculated regarding water as work medium in the conditions of different ratio of inlet pressure and outlet pressure. The flow field in venturi is simulated by fluid dynamics. The results show that the velocity in throat location and maximum cavitation volume fraction increase with ratio of inlet pressure and outlet pressure increasing. The area of cavitation extends. The pressure in throat location reduces and then become stable. The maximum growth rate of single bubble and pressure pulse in bubble increase significantly. The recurrence times of growth and collapsing increases. The influence of single bubble dynamics on the distribution of the whole flow field depends on the turbulence intensity. The more severe the turbulence in venture, the less the effect of single bubble on the whole flow field.

Abstract: The screw shaft is the main structure of the horizontal dryer used in polysilicon industry. It is the key factor for dryer to work normally that strength and stiffness of shaft and mixing arms meet the standard. According to material properties and working environment, the models of shaft and mixing arm were built respectively by ANSYS. The deformation and stress distribution were obtained through finite element analysis which provided reference for design and optimization. The results show that the shaft and mixing arm satisfy the requirement of strength and stiffness.

Abstract: Thrust bearing is one of the most important components in ESPCP system, which determines the life of the whole system under the restriction of some factors such as the installation depth and the viscosity of swabbed petroleum oil etc. To increase the ability of high temperature resistance of thrust bearings under the limited radial size, the damage reason of applied bearings was analyzed. Some different modified methods were employed on configuration and material. Contact problems were researched with finite element analysis software. Comparison of the analysis results shows that in the tube, it is optimum that 8 rollers thrust bearings are used in 10mm radial tube without holders.

Abstract: In this paper, a new polymer process machine--- centrifugal extruder is introduced. The pressure and temperature distribution of centrifugal extruder has been studied by theoretical analysis, which is based on mathematics and experiments. The results show that the pressure and temperature Distribution can provide the processing of solid-plug conveying sufficiently and stably, which can prove the industry practicability of centrifugal extruder.

Abstract: In this paper, the output can not meet the operating requirements problems of power plant desulfurization device wet mill system operation, site of the optimization test of wet mill system, optimization and adjustment, wet mill output and fineness of limestone reached or better than the design value, the operation time was shortened, and achieved good economic and social benefits. With reference to the same type of wet overflow type ball mill.

Abstract: Gas distributor is of vital significance to the stability of hydrogenation reaction. The distribution performance of original style was studied with CFD numerical simulation method and an improved distributor was proposed in this paper. Compared with the original style, the new structure overcame the center-manifold phenomenon. The velocity distribution of the new distributor at evaluation plane was more uniform and pressure drop was smaller. The distribution performance of the new distributor was better, and the improved structure of the new distributor was obtained through further investigation, which will provide instructional information for industry application.