Growth mechanism and the dependence of granule size on drop size in fluidized-bed granulation

Waldie, B.

doi:10.1016/0009-2509(91)85147-p

Cited by 59 publications

(27 citation statements)

References 3 publications

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“…Such a delivery of liquid to bulk material promotes, in the presented range of parameters and in case of a given material, the formation of granulation nuclei which produce 6 -8 mm agglomerates (larger than the size of delivered droplets). This trend is consistent with the results of other studies (Schaafsma et al, 1998;Waldie, 1991). Observations of droplet wetting phenomenon both during granulation and preliminary analysis ruled out the possibility that droplets broke into smaller pieces while falling from the height of a mounted nozzle tip and resulting in formation of nuclei of smaller diameters.…”

Section: Resultssupporting

confidence: 92%

“…Also, the correlation between droplet size and the distribution of nucleus sizes in fluid bed granulators was demonstrated. According to Waldie (1991) one droplet usually tends to form one nucleus, and the size of formed granule is larger than droplet size. The intensity of liquid binder delivery is one of the most widely studied variable parameters influencing binder distribution.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Disaccharide Concentration in a Liquid Binder on The Mechanisms and Kinetics of Disc Granulation

Obraniak

Gluba

2017

Chemical and Process Engineering

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Analysis of granulation kinetics was carried out using a laboratory disc granulator with a diameter D of 0.5 m. A liquid binder was delivered to the tumbling bed at a constant flow rate with a nozzle generating droplets with a size of approx. 4-5 mm. Fine-grained chalk was used as a model of raw material and water or disaccharide solution with concentrations of 20 -40% as a wetting liquid. Different times of droplet delivery ranging from 2 to 6 min were utilized. Granulometric composition of the bed for selected lengths of process, bed moisture and the moisture of individual size-fractions were assessed. Mass of granulated material, which was transferred from nuclei fraction to other size fractions was determined on the basis of mass balance analysis and the assessment of liquid migration between fractions. The influence of disaccharide concentration in wetting liquid on the aforementioned phenomena was also examined.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

The Effect of Disaccharide Concentration in a Liquid Binder on The Mechanisms and Kinetics of Disc Granulation

Obraniak

Gluba

2017

Chemical and Process Engineering

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“…For example, Waldie et al (1991) found a direct relationship between droplet size and granule size in granulation of glass microbeads (mean dimeter circa 150 pm). Larger droplets bound more particles together than small droplets.…”

Section: )mentioning

confidence: 99%

Fundamentals of bitumen coking processes analogous to granulations: A critical review

Gray

2002

Can J Chem Eng

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estern Canada has enormous resources of bitumen in oilsands deposits, estimated at 4.6 x 10" m3 (NEB, 2000), of which W 12% is recoverable using current technology of either openpit mining or in situ production by steam assisted gravity drainage. This bitumen requires extensive processing in order to produce transportation fuels and petrochemicals. The bitumen contains 50-60 weight % of vacuum residue, i.e., components that cannot be distilled, which must be converted to distillable fractions. The main commercial technologies to accomplish this production are coking the vacuum residue to produce a carbon rich coke solid, distillable liquids and light ends, and hydroconversion with catalyst or additives at high pressure with hydrogen gas (Gray, 1994). Due to a variety of economic and historical factors, coking processes account for the large majority of installed and announced capacity in Canadian upgrading operations. The importance of coking makes further improvements to a process vital to the Canadian oilsands industry.A number of process variables are significant in coking processes, but the two most important are the method used to heat the oil and the residence time of the cracked products in the reactors. The most common process worldwide is delayed coking, where the feed oil is heated in a furnace then introduced into a coke drum. The liquid feed cracks in the coke drum to produce vapour products, light ends and coke. The process operates at low pressure (0-300 kPa) and temperatures of 450-51 0°C (Nelson, 1958). The alternative established commercial coking process is based on a fluid-bed reactor. In fluid coking, the feed is sprayed into a fluidized bed of coke particles (Figure 1; Gray, 1994).The liquid reacts on the surface of the hot particles, again cracking to give distillate products, light gases and coke. The higher reaction temperature (500-540°C) and short residence time of the cracked vapour in the reactor give a higher yield of distillate products relative to coke plus light ends (Nelson, 1958). For example, the yield of coke from fluid coking is approximately 68% of the yield of coke from delayed coking for a range of feed oils. The higher yield of liquid product from fluid coking, for a given feed, is usually attributed to the higher operating temperature and the lower gas-phase residence time of the cracked vapours than in delayed coking.Recent development of thermal cracking processes has sought to enhance the yield of liquid products by reducing the residence time of the cracked vapours still further, and by enhancing the heat transfer 'Author to whom correspondence may be addressed. E-mail address: murray.gray@ualbena.caA number of coking processes use hot particles to heat liquid bitumen or petroleum residue to cause cracking reactions. These particles may be mineral or coke solids. Interactions of these particles, in fluid beds, moving beds and other types of contactors, are governed by the liquid films on the particle surfaces. This paper explores the analogy between granulation and co...

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“…The sieve analysis results indicate that for all wetting times, the fraction with the size from 6.3 to 8 mm and neighboring fractions have a dominant contribution in the formed granulate. Reference data [32,33] prove a distinct correlation between the drop size and the distribution of nuclei size in granulators such that a single drop aims at forming a single granule in accordance with an equation:…”

Section: Tests Resultsmentioning

confidence: 99%

Spectrophotometric analysis of disintegration mechanisms (abrasion and crushing) of agglomerates during the disc granulation of dolomite

Obraniak

Ławińska²

2017

Granular Matter

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The analysis of mechanisms which affect the formation of agglomerates and determine the granulation process in a broad sense encounters difficulties related to the many ways of the formation of granules. The aim of the study was to perform a qualitative and quantitative analysis of granulation mechanisms with special reference to agglomerates' disintegration in the disc granulation process. This paper contains an analysis of disintegration mechanisms (abrasion and crushing) of agglomerates during the disc granulation of dolomite. The analysis of the mechanisms taking place during the process concerns the granulation stage after wetting. During the research, each time after the wetting stage, the size fraction 10-12.5 mm was substituted with an analogous fraction wetted by means of an aqueous solution of a coloring agent and the process was continued. After the specified time of granulation, the obtained product was sieved through laboratory sieves and then the content of the provided coloring agent in different size fractions was analyzed by means of a spectrophotometer. Measuring the absorbance of the analyzed samples and granulometric composition of the bed, the level and cause of the migration of material of the tested fraction into other size classes were determined, and at the same time, the occurring granulation mechanisms were analyzed. The proposed model and measurement method consisting of determining the absorbance of the tested granulometric fraction enable the qualitative and quantitative analysis of granulation mechanisms are encountered during the carrying-out of the process after wetting the bed.

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Growth mechanism and the dependence of granule size on drop size in fluidized-bed granulation

Cited by 59 publications

References 3 publications

The Effect of Disaccharide Concentration in a Liquid Binder on The Mechanisms and Kinetics of Disc Granulation

The Effect of Disaccharide Concentration in a Liquid Binder on The Mechanisms and Kinetics of Disc Granulation

Fundamentals of bitumen coking processes analogous to granulations: A critical review

Spectrophotometric analysis of disintegration mechanisms (abrasion and crushing) of agglomerates during the disc granulation of dolomite

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