Hot corrosion behaviour of Ni3Al in sulphate-chloride mixtures in the atmosphere

Hot corrosion of Ni₃Al intermetallic compound in the presence of sulphate-chloride mixtures was studied. A comminuted Ni₃Al mixed with NaCl-Na₂SO₄, NaCl-Li₂SO₄, LiCl-Na₂SO₄, LiCl-Li₂SO₄ additions was oxidized in the air up to 1000 °C with linearly increasing temperature and isothermally within the temperature range of 500-700 °C. The corrosion process was observed by thermogravimetric method using Mettler thermoanalyzer.The experiments indicated that LiCl (∼10 wt.%)-Li₂SO₄ mixture was the most corrosive agent. It was also found that by addition of MgO the corrosion of Ni₃Al was reduced. Phase composition of the corrosion products was established by X-ray diffraction analysis; there were detected Al₂O₃, Al₂S₃, NaAlO₂ (or LiAlO₂) as intermediate products, nickel sulphides, NiO and NiAl₂O₄. NiAl₂O₄ spinel was formed only at the highest temperatures, while at lower temperatures alumina was present instead of spinel.Hot corrosion behaviour of Ni₃Al in sulphate-chloride mixtures in air atmosphere.     

Physical and sensory characteristics and probiotic survival in ice cream sweetened with various polyols

The effect of polyols (xylitol, erythritol, maltitol and isomalt) on physical and sensory properties of probiotic ice cream, as well as the survival of Bifidobacterium BB‐12 during freezing over 28 days of frozen storage, was investigated. The control sample of ice cream, sweetened with sugar, showed a lower pH and higher overrun than those sweetened with polyols. The viable bifidobacteria counts remained above 8 log cfu/g in all samples. The amount of erythritol added was not enough to obtain a similar sweetness as in control, but too high to get an ice cream with good textural properties.     

Evolution of the distribution function of the composition of oxide inclusions for the growth model of a disperse system formed during deoxidation

The growth model for nuclei of oxide inclusions growing during the process of steel deoxidation is proposed. The evolution of the inclusion composition has been analysed by solving the continuity equation for the probability-density function f(x,t) (where x is the oxide mole fraction). The calculations were carried out for model parameters and for steel deoxidation by aluminium or silicon-manganese. The result obtained cannot be verified due to the lack of any functional dependence relating chemical composition to inclusion radius.     

Theoretical model of steel desulphurisation with gaseous calcium

A model of desulphurisation of steel with gaseous calcium bubbles based on a population balance equation is presented. The equation is a basis of the quantitative approach to the phenomena observed in the dispersive systems. The course of reaction of the calcium bubbles with the oxygen and sulphur during the Stokes float-out was studied for various model parameters. The effect of the following factors on the refining process efficiency was considered: interval of bubble sizes, distribution of bubble sizes and participation of a carrier gas. It was found that the refining process is affected mainly by the global bubble surface and the residence time of bubbles in the steel. It means that the bubble size interval and size distribution of the bubbles for the calcium mass is a decisive factor for the desulphurisation efficiency. Any increase in the carrier gas content, in fact, increases the bubble surface, yet, simultaneously accelerates the float-out of the not reacting bubbles. Thus, for the Stokes model the effect of a carrier gas on the desulphurisation efficiency is small. The comparison of the calculated and experimental results for different blowing depths and different amounts of calcium is presented.     

Comparison of hazelnut and peanut shells combustion in bubbling fluidized-bed combustor

The combustion of peanut and hazelnut shells was studied in an atmospheric bubbling fluidized bed. The impact of the enrichment of air with oxygen and the flow rate of fluidizing gas on CO₂ and CO concentrations was analyzed. It was stated that in air enriched with oxygen up to 25% the mole ratios of CO₂ to CO were improved by 15–30%, depending on the flow rate used. For the peanut shell the combustion of volatiles with a hematite as an oxygen carrier was also studied. The effects were observed above ~ 450°C.