Drying of granulated materials. Part I. Drying of a single granule

Krevelen, D.W. Van; Hoftijzer, P. J.

doi:10.1002/jctb.5000680207

Cited by 25 publications

(16 citation statements)

References 7 publications

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“…Let the area increment in the time interval between tЈ and tЈϩdt be dA(tЈ). Then at the time t 1 (t 1 ϾtЈ) the mass transfer rate through the area is .... (23) And during the time from 0 to the bubble formation time t f , the number of moles of desulfurization, n S,f , may be written as ... (24) where the bubble surface area is expressed as ........ (25) According to the ideal gas equation, the gas flow rate QЈ i in Eq. (25) follows that ................. (26) where iϭAr, Mg, or (Mg, S).…”

Section: Mass Transfer Model During Bubble Formationmentioning

confidence: 99%

Desulfurization of Molten Iron with Magnesium Vapor Produced In-situ by Carbothermic Reduction of Magnesium Oxide.

et al. 2001

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A new method of desulfurization of molten iron has been developed with magnesium vapor produced insitu by carbothermic reduction of magnesium oxide. Pellets, the main composition of which was magnesium oxide and carbon, were charged into a graphite tube. The tube was immersed into the molten iron to produce magnesium vapor. This process has been studied experimentally and theoretically. The rate of desulfurization depended mainly on the rate of reduction of magnesium oxide. Under the present experimental conditions, the desulfurization rate increased with increasing temperature and Ar carrier gas flow rate. The change in melt mass had little influence on the desulfurization efficiency of magnesium. The effect of pellet composition on the desulfurization has also been investigated. A mathematical model of the desulfurization has been proposed. The calculated results are in good agreement with the experimental results. The rate-controlling step changes with the progress of desulfurization during bubble formation and ascent periods. At the beginning of the formation period, both of the mass transfer of sulfur in the melt and magnesium in the bubble should be considered as rate-controlling steps. At the end of the ascent period, the magnesium partial pressure in the bubble decreases close to the value in equilibrium with the sulfur concentration in the melt. The mass transfer of magnesium in the bubble becomes much slower than that of sulfur in the melt and becomes the rate-controlling step. The desulfurization reaction mainly takes place on the bubble surface. The amount of desulfurization during the bubble formation period is larger than that during the bubble ascent period. Effects of pellet mass and initial sulfur concentration on desulfurization can be reasonably explained by the present mathematical model.

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Section: Mass Transfer Model During Bubble Formationmentioning

confidence: 99%

Desulfurization of Molten Iron with Magnesium Vapor Produced In-situ by Carbothermic Reduction of Magnesium Oxide.

et al. 2001

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“…A number of models have been developed for predicting the bubble volume under the constant flow condition. [5][6][7][8][9][10] Most models show the bubble volume is calculated by the following equaion. (4) where k is the constant listed in Table 1 and g is the gravitational acceleration.…”

Section: Mean Size Of Bubblesmentioning

confidence: 99%

Gas Injection from Slot Nozzles with Various Shapes in Water.

2000

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Results of experiments examining behaviour of gas bubbles detouching from slot nozzles of various shapes are presented. Gas was injected into water through the slot nozzles of 200 mm in length and 0.05, 0.1 mm in width. Four types of the slot nozzles were used: (a) flat nozzle, (b) mountain-shaped nozzle, (c) valley-shaped nozzle, (d) unilaterally inclined nozzle. They were made of Teflon which is poorly wetted by water. The bubble behavior is described by two parameters: bubble diameter formed at the slot nozzle and the number of bubble sources. It was found that the gas injection through the mountain-shaped nozzle produces the smallest bubble while the largest bubble is formed when the valley-shaped nozzle is used. Bubbles produced at the flat nozzle and unilaterally inclined nozzle were almost the same in size which is intermediate between the bubble sizes for the mountain-shaped and valley-shaped nozzles. Comparative experiments showed that, when gas is injected through a wetted slot nozzle, the bubble size is much smaller than that for the nonwetted slot nozzle of the same design (flat nozzle) at lower gas flow rates. For all experiments, the bubbles become smaller as the number of bubble sources increased.

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“…Studies of bubble formation and the formation of interfacial area have been made by use of capillary tubes, porous plates, nozzles, slots, perforated plates, and orifices (2,4,6,9,15). Of method developed by these workers for the measurement of the interfacial area required that the interfacial area (cm.-') times the optical path length (cm.)…”

Section: Al ( L O ) Calderbank ( 4 ) and Walters And Davidsonmentioning

confidence: 99%