Fluidized-bed Equipment Research Articles

Optimal startup conditions of fluidized-bed boiler

A mathematical model is developed permitting optimization of the startup of fluidized-bed equipment in which an exothermal reaction is occurring, by numerical-experiment method. The results obtained are tested for a semicommercial 8-MW power boiler.

The effect of product bed temperature on the microstructure of Aquacoat-based controlled-release coatings

Diphenhydramine HCl pellets were coated at various bed temperatures in a laboratory-size fluid-bed equipment. Optimum coalescence of an Aquacoat formulation was achieved when the bed temperature was kept between 30 and 40°C. Coating applied outside this temperature range resulted in the formation of poorly coalesced films and faster release rates. The fast release rates of pellets coated at low bed temperatures were attributed primarily to drug migration into the film layer during the coating process and to incomplete film formation due to hardening of the uncoalesced polymer spheres, which, presumably, had a relatively higher minimum film formation temperature. At high bed temperatures, the rate of evaporation of water is so fast that it does not allow the migration of drug from the substrate into the film layer. The fast release rates observed were, therefore, believed to be due to the development of porous films during the coating process.

Cell model of the kinetics of granule formation in fluidized-bed equipment

The results of numerical and experimental investigation of the kinetics of granulation in fluidized beds are outlined.

An Evaluation of Tricalcium Phosphate Excipients Particularly Using Instrumented Rotary and Single Station Tablet Presses

AbstractTwo direct compression grades of tricalcium phosphate, Tri-CompressR (Edward Mendell Co., Inc.) and Tri-TabR (Stauffer Chemical Co.), and a product containing tricalcium phosphate, D locust bean gum and citric acid, Loco-TabR (Ingredient Technology Corp.), were studied. Loco-Tab is composed of smaller particles having more irregularly shaped surfaces than the others. It is also less dense and somewhat less flowable than the other materials. None of these excipients lost weight at elevated temperature and none can be considered to be hygroscopic. Compressibility in formulations was studied using instrumented rotary and single station tablet presses. In all cases, the single station press yielded harder tablets at a given compression force. Dissolution of an insoluble drug was affected to a degree by the press used. Drug dissolution from Loco-Tab formulations was excellent at all tablet hardnesses, a highly desirable property for tablets to be coated using fluidized bed equipment. Loco-Tab would see...

Grundlagen der Wirbelschichttechnik

AbstractFundamentals of fluidized bed technology. Although gas/solids fluidized beds have long been successfully employed in a variety of industrial processes, the design and optimization of fluidized bed reactors still presents considerable difficulties, owing to the complex nature of gas/solids flow in the fluidized bed. The present review collects various flow‐mechanical principles for the design of fluidized bed equipment. The central role of flow mechanics in the operating properties, and in particular for scale‐up of fluidized bed reactors, is illustrated for the model of a simple heterogeneously catalyzed gas‐phase reaction.

Abrasion of granulates of pharmaceutical products in fluidized bed equipment

Abrasion of granulates of pharmaceutical products in fluidized bed equipment

Sectionalized fluidized-bed equipment for solution granulation

A mathematical model is presented for solution granulation; the model has been tested by experiment. The model indicates that sectionalized equipment is suitable.

Calculations foe single-stage fluidized-bed equipment for cooling mineral fertilizers

Calculations foe single-stage fluidized-bed equipment for cooling mineral fertilizers

Certain features of operation of fluidized bed equipment not having grid plates

Certain features of operation of fluidized bed equipment not having grid plates

Performance of return-flow channels in fluidized-bed equipment

Overflow of free-flowing materials into a fluidized bed from an upright channel in countercurrent gas filtration is investigated. Equations for calculating the weight rate of flow of the free-flowing material and the critical counterpressure are proposed.