Drying of thermally-weak organic powder in a centrifugal fluidized bed

The drying characteristics of thermally-weak organic powders of [2,2-Azobisisobutyrinitrile(AIBN) and HN] were studied in a centrifugal fluidized bed, since any kind of heating and hot gas cannot be employed for the drying of thermally-weak organic powders to prevent from sensitive reaction or decomposition during being dried. It could be a solution to use highly amount of gas in the centrifugal field for the drying of thermally-weak organic powders, which could overcome the limitation of gas velocity for the more efficient drying. The effects of gas velocity, rotational speed of the bed, initial moisture content of the powder, and amount of powder loading on the drying characteristics were determined. The pressure drop in the bed displayed an almost constant value that had a plateau, with increasing gas velocity. The moisture content of the organic powder decreased with an increase in the gas velocity or rotational speed of the bed, however, its variation trend did not change considerably with a variation of feed loading or an initial moisture content within this experimental conditions. The variation of the drying rates with respect to the moisture content was almost linear in the falling rate period.     

The electrification mechanism in a fluidized bed

On the basis of numerous data available in the literature, as well as according to the experiments which we have carried out, a hypothesis is proposed for the mechanism of static electrification in a fluidized bed.     

Change in heat-transfer coefficient in the drying of heat-insulated materials in a fluidized bed

An analysis is presented of the causes of the apparent reduction in the heat-transfer coefficient from a fluidized bed to the surface of an article immersed in it in the course of drying.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol.31, No.1, pp.129–133, July, 1976.     

Boride coatings on non-ferrous materials in a fluidized bed reactor and their properties

Fluidized bed technology has been successfully used in the formation of different types of coatings, e.g. aluminizing [Surf. Coat. Technol. 120 (1999) 151; Steel Res. 66 (1995) 318; J. Mater. Sci. 35 (2000) 5493], chromizing [Surf. Coat. Technol. 120 (1999) 151; Steel Res. 66 (1995) 318; J. Mater. Sci. 35 (2000) 5493], nitriding [Heat treatment in fluidized bed furnaces, 1993], carburizing [Heat treatment in fluidized bed furnaces, 1993], carbonitriding [Heat treatment in fluidized bed furnaces, 1993]. Recently, this technology has been used for the deposition of hard boride layers onto ferrous substrates [Mater. Lett. 51 (2001) 156; Fifth International Conference on Heat Treatment Materials, Budapest, Hungary, vol. 3, 1986]. In the present paper, we used fluidized bed technology to deposit boride coatings onto non-ferrous metals and alloys. The coatings were examined by means of optical microscopy, Vickers microhardness and X-ray diffraction, to determine thickness and morphology, phase formation and properties. The properties of dry wear and thermal cycling oxidation of the coatings were evaluated. The as-produced coatings were characterized by adequate thickness and improved wear and oxidation resistance.     

Boride coatings on non-ferrous materials in a fluidized bed reactor and their properties

Fluidized bed technology has been successfully used in the formation of different types of coatings, e.g. aluminizing [Surf. Coat. Technol. 120 (1999) 151; Steel Res. 66 (1995) 318; J. Mater. Sci. 35 (2000) 5493], chromizing [Surf. Coat. Technol. 120 (1999) 151; Steel Res. 66 (1995) 318; J. Mater. Sci. 35 (2000) 5493], nitriding [Heat treatment in fluidized bed furnaces, 1993], carburizing [Heat treatment in fluidized bed furnaces, 1993], carbonitriding [Heat treatment in fluidized bed furnaces, 1993]. Recently, this technology has been used for the deposition of hard boride layers onto ferrous substrates [Mater. Lett. 51 (2001) 156; Fifth International Conference on Heat Treatment Materials, Budapest, Hungary, vol. 3, 1986]. In the present paper, we used fluidized bed technology to deposit boride coatings onto non-ferrous metals and alloys. The coatings were examined by means of optical microscopy, Vickers microhardness and X-ray diffraction, to determine thickness and morphology, phase formation and properties. The properties of dry wear and thermal cycling oxidation of the coatings were evaluated. The as-produced coatings were characterized by adequate thickness and improved wear and oxidation resistance.     

Model for heat exchange between a well-developed fluidized bed and a surface within the bed

A physical model for heat exchange between a fluidized bed and a surface in contact with it is proposed and discussed. The heat exchange is due to heat transfer by oscillating particles.     

Relationships for a fluidized bed of solid particles

A new theory for a fluidized bed is presented and corroborated by experimental data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 18, No. 6, pp. 1122–1130, June, 1970.     

The hydrodynamics of a centrifugal fluidized bed in a solid-liquid system

We have studied the conditions for the appearance of a centrifugal fluidized bed in a solid-liquid system, and these conditions are governed by the critical velocities and pressure difference.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol.16, No. 3, pp. 526–530, March, 1969.     

The sulphidation of alloys used in a fluidized bed combustor

The results of an investigation of the sulphidation behaviour of lncoloy BOOH and AISI 310 stainless steel in coal combustion conditions at temperatures between 650°C and 900°C are presented. Laboratory tests were carried out in controlled environments in the presence of solids representative of fluidized bed combustor operation. The morphology and composition of scale formed during sulphidation was examined and compared with that from tube samples removed from test rigs operated by the National Coal Board. The results have shown that at 900°C a gas mixture corresponding to the equilibrium conditions close to the coexistence point for CaS0₄, CaO and CaS on the phase stability diagram is sufficient to induce sulphidation. However, at lower temperatures an interaction between the deposit and the protective oxide is necessary and in some cases the presence of typical contaminants found in coals is an added requirement. The morphology of the corrosion products found in practice can be reproduced under controlled conditions in laboratory tests. The results are interpreted in terms of likely mechanisms of the processes involved.     

Using experimental design to optimize the process parameters in fluidized bed granulation

In this study many parameters were screened for a small-scale granulation process for their effect on the yield of granules between 75 and 500 μm and the geometrical granule mean size (d50). First a Plackett-Burman design was applied to screen the inlet air temperature, the inlet flow rate, the spray rate, the nozzle air pressure, the nozzle spray diameter, and the nozzle position. The Plackett-Burman design showed that the key process parameters were the inlet flow rate and the spray rate and probably also the inlet air temperature. Afterward a fractional factorial design (2^5-2) was applied to screen the remaining parameters plus the nozzle aircap position and the spraying time interval. The fractional factorial design showed that the nozzle air pressure was also important. As the target values for the granule yield (between 75 and 500 μm) and the geometric mean granule size (between 300 and 500 μm) were reached during the screening experiments, further optimization was not considered necessary.     

The dynamic analysis of a small fluidized bed combustor

The dynamic characteristics of a small fluidized bed combustor for coal were examined analytically and experimentally.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 25, No. 3, pp. 476–484, September, 1973.We would like to thank J. J. Henderson, of the Faculty of Electronics and Electrical Engineering of Birmingham University, for his advice and assistance in this work.     

The mechanism of heat transfer of particles in a fluidized bed

The relationship between the contact and convective-conductive components of the heat flux in the heating of particles in a fluidized bed is examined.     

Novel method of air distributor design for enhancing bed stability and reducing impurities in gas–solid fluidized bed system

Coal plays a key role in the economic development of China. It is greatly significant to improve the efficient use of coal through high-efficiency dry separation. In this paper, a porous sponge was used to optimize the air distributor, and its fluidization characteristics were studied. Response surface methodology was used to study the collaborative optimization effects of gas velocity, separation time, and bed height on the fine coal separation. Gas velocity was the main factor which affects separation efficiency. When separation is in operation parameters, the yield and ash content were 65.48 and 10.89% as to the clean coal product and 9.24 and 80.47% as to the gangue product, respectively. Furthermore, the yield and ash content of middlings were 25.29 and 20.32%, respectively. The probable error, E, values were between 0.085 and 0.100?g/cm³. Using XRF and FTIR analysis, it was observed that the harmful elements and impurities in coal were reduced during the separation process.     

Heat transfer between a fluidized bed and the surface

The functional dependence of the coefficient of conductive-convective heat transfer on the determining factors is predicted based on the two-zone model of heat transfer in concentrated dispersed media. The effect of the nonisothermal nature of the fluidized bed on the magnitude of the effective emissivity of the bed is taken into account. General formulas for calculating the coefficients of complex heat transfer were derived and checked in a very wide range of experimental data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 58, No. 4, pp. 597–604, April, 1990.     

The temperature field of a fluidized bed in continuously operational equipment

We examine the nonsteady distribution of temperatures in a fluidized bed when granular material is fed continuously into the bed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol.16, No. 2, pp. 316–319, February, 1969.     

Spectra of thermal fluctuations in a fluidized bed

We have studied the spectra of temperature fluctuations and the heat-transfer coefficient in a disperse medium, and have compared the results with experimental data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 47, No. 1, pp. 116–124, July, 1984.