Coating fluidized-bed

Almost all PVC powder coatings are appHed by the fluidized-bed coating process. Although some electrostatic spray-grade formulations are available, they are very erratic in their appHcation characteristics. The resistivity of plasticized PVC powders is low compared to other powder coating materials and the appHed powder quickly loses its electrostatic charge. For the same reason, PVC powders show poor appHcation characteristics in an electrostatic fluidized bed and are seldom used in this process. 

G-VG G-VG Molded by all processes, fluidized bed coatings High-temperature valve seats, chemical resistant pipe, coated vessels, insulation... 

A.H. Landrock, Fluidized-Bed Coating with Plastics Technology and Potential for Military Applications , PLASTEC Rept 13 (1964)... 

Microspheres and microcapsules of lactide/glycolide polymers have received the most attention in recent years. Generally, three microencapsulation methods have been employed to afford controlled release formulations suitable for parenteral injection (1) solvent evaporation, (2) phase separation, and (3) fluidized bed coating. Each of these processes requires lactide/glycolide polymer soluble in an organic solvent. 

Processes based on fluidized bed coating have been developed (49). In this process, the bioactive agent is dissolved in an organic solvent along with the polymer. This solution is then processed through a Wurster air suspension coater apparatus to form the final microcapsule product. A solvent partition technique based on continuous injection of a polymer-drug solution into flowing mineral oil has been reported (50). 

The primary applications for large-scale jetting fluidized beds are in the area of coal gasification as described by Yang et al. (1995), Kojima et al., (1995), and Tsuji and Uemaki (1994). Smaller scale applications are for fluidized bed coating and granulation to be discussed in Chapter 6. 

The main goal of this chapter is to provide a technical basis or framework for analyzing fluidized bed coating and granulation operations. 

Fluidized Bed Coating Equipment. In reviewing the literature, it is evident that there are a great many variations in fluidized bed equipment used in coating applications (Olsen, 1989a and 1989b Jones, 1985 and Mehta,... 

Scale Up of Process. The scale up of fluidized bed coating processes has received little attention in the literature. Current practices in the pharmaceutical industry are reviewed by Mehta (1988). The basic approach described by Mehta (1988) is to scale the airflow and liquid spray rates based on the cross-sectional area for gas flow. This seems reasonable except for the fact that in the scaling of the equipment, the height of the bed increases with increasing batch size. For this reason, a time scale factor is also required. 

Landrock, A. H., Fluidized Bed Coating with Plastics, Chem. Eng. Progr., 63 67-74(1967)... 

Tsutsumi, A., Nakmoto, S., Mineo,T., and Yoshida, K., A Novel Fluidized-Bed Coating of Fine Particles by Rapid Expansion of Supercritical Fluid Solutions, Proc. 1st Int. Particle Technol. Forum, pp. 452-455, Denver, CO (1994)... 

Wan, L. S. C., and Lai, W. F., Factors Affecting Dmg Release from Drug-Coated Granules Prepared by Fluidized-Bed Coating, Int. J. Pharmaceutics, 72 163-174(1991)... 

Electrostatic fluidized-bed coating, 7 55-56 Electrostatic forces, 9 569, 570 11 800 and adsorbent selectivity, 1 584 in adsorption, 1 583 in solvent-solute interactions, 23 91-92 Electrostatic particle forces, in depth filtration theory, 11 339 Electrostatic precipitators (ESP), 11 714 13 180 23 552 26 699-706 advantages of, 26 700 applications of, 26 701-703, 705t design considerations related to,... 

Fluidized-bed classifiers, 16 619 Fluidized-bed coating, 7 55—56 Fluidized-bed cracking, 10 618-619. See also Fluidized-bed catalytic cracking (FCC) Fluidized-bed dehydrogenation technology, 20 779... 

Teunou and Poncelet (2002), in their extensive review of fluidized bed coating, identify three geometries for continuous processing. First, the monocellular bed which is essentially the type of equipment used... 

Dewettinck, K. and Huyghebaert, A., Top-spray fluidized bed coating effect of process variables on coating efficiency, Lebensmittel Wissenschaft Technologie, 31 (1998) 568-575. 

Kang, H.A. and Shin, M.G., Effect of inlet air temperature and atomizing air pressure on fluidized bed coating efficiency of broken peanut, Korean J. Food Sci. Tech., 34 (2002) 924-926. 

Turkoglu M, Sakr A. Mathematical modelling and optimization of a rotary fluidized-bed coating process. Int J Pharm 1992 88 75-87. 

Jones DM. Effect of process air dew point on a top-spray fluidized bed-coating process. Presented in Session 265 Coating in the pharmaceutical industry. Proceedings of AIChE Annual Meeting, 1998. 

Fluidized bed coating solid particles (50-500 pm) suspended in tempera-tine- and humidity-controlled chamber of high-velocity air where coating is atomized... 

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