This paper presents the results of numerical flow simulation in ventilation mill of Kostolac B power plant, where louvers and centrifugal separator with adjustable blade angle are used. Numerical simulations of multiphase flow were performed using the Euler-Euler and Euler-Lagrange approach of ANSYS FLUENT software package. The results of numerical simulations are compared with measurements in the mill for both types of separators. Due to very complex geometry and large number of the grid cells, convergent solution with the Eulerian model could not be obtained. For this reason the mixture model was employed resulting in very good agreement with measurements, concerning the gas mixture distribution and velocity at the main and secondary burners. There was large difference between the numerical results and measurements for the pulverized coal distribution at the burners. Taking into consideration that we analyzed dilute mixture with very low volume fraction of the coal, the only choice was the Euler-Lagrange approach, i.e. discrete phase model limited to volume fraction of the discrete phase less than 10-12%. Obtained distributions of the coal at the burners agree well for both types of separators

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B. Katavic ´and Z. Odanovic ´microconstituent's behaviour during deformation and heat treatment was investigated as well. This paper presents the effects of vacuum heat treatment under different cooling conditions on mechanical and structural properties of forged heavy alloys, EXPERIMENTAL such as 92•5W-5Ni-2•5Fe and 92•5W-5Ni-2•5Fe Material microalloyed with Co. The tungsten compositionThe commercially produced W-Ni-Fe heavy alloys and in the c phase has proved to be higher and more those microalloyed with Co (W-Ni-Fe+Co) were examhomogenous in the rapidly cooled alloys than in the ined. The as received W-Ni-Fe alloy was sintered and slowly cooled ones. The effects of chemical composannealed (NE), and samples were prepared in the form of ition inhomogeneity on mechanical and structural round rods, 36 mm in diameter. The W-Ni-Fe+Co alloys properties of alloys were also analysed and discussed.were received in sintered (S), and sintered then annealed The results of tensile and toughness testing have (SA) condition. These samples were prepared in the form shown an increase in ductility and toughness, while of round rods, 20 mm in diameter. the strength of heat treated alloys decreased in com-The chemical composition was determined by an atomic parison with the strength of forged alloys. The absorption spectrophotometer (AAS). Carbon, sulphur and fracture analysis has shown that in the sintered and oxygen content was determined by a Lecco apparatus. The rotary forged alloys, intergranular fracture of the chemical compositions of the alloys are presented in Table 1. tungsten phase and transgranular fracture of the c phase occurred, respectively. The fracture of these Rotary forging and heat treatment phases after heat treatment was characterised byThe S and SA rods were rotary forged with compression transgranular morphology.PM/1070 strains of 20%, and the NE rods were rotary forged with compression strains of 30%. These rods were preheated up The authors (

This paper describes the effects of rotary swaging and heat treatment under different conditions on mechanical properties and microstructure of the P/M 91W-6Ni-3Co alloy. The investigation was performed on cold rotary swaging rods with 10, 20 and 25% reduction in area, heat treated at 11300C for 90min under different cooling conditions and strain-aged at temperatures from 300 to 8000C for 60, 180 and 360min. Tensile and toughness testing of rotary swaging rods showed that increase in the reduction resulted in intensive strengthening and toughness lowering. The results of tensile and toughness testing of heat treated rods have shown a decrease in strength, ductility and partly toughness in comparison with the mechanical properties of swaged alloys. The results of strain aged rods demonstrate that, for this cold rotary swaging alloy, there is a temperature range from 500 to 6000C for 60min in which the maximum ultimate strength and hardness may be attained

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