Material balance granulator

Sherrington (S10) has presented a static model of the granulation loop operating in the snowballing mode. The model combines the solution phase theory in Eq. (106) with the material balance across the granulator. The recycle ratio defined as recycle/raw solid feed, is given by... 

A reaction is conducted in an annular vessel with catalyst whose bulk density is pc. Porosity of the bed is e. The reaction is first order with specific rates kc per unit mass on the catalyst and kh per unit volume in the space not occupied by the granules. The two walls are maintained at temperatures Tx and T2 The reaction also proceeds on the walls with corresponding specific rates kwl and kw2 per unit area. Only radial diffusion occurs. Write equations of the material balances and the boundary conditions. 

Pan granulation of CAN has proven difficult because the pan is very sensitive to heat and material balance factors. The product shape is irregular. The Sphcrodizeti processes and all other processes need additives ... 

The authors would like to acknowledge that the section dealing with population balance modeling of granulation processes is an abbreviated version of material prepared by Dr. J. D. Litster, University of Queensland, for a joint short course given by Dr. B. J. Ennis and Dr. J. D. Litster. 

Adetayo, A. A., Litster, J. D., Pratsinis, S. E., and Ennis, B. J., Population Balance Modelling of Dram Granulation of Materials with Wide Size Distributions, Powder Tech, 82 37-49 (1995)... 

Sales of Ca supplements alone were 875 million in the United States in 2002, and comprised 60% of all mineral supplement sales (Anonymous, 2004). In 2004, sales of Ca supplements increased by 9.3% (Uhland et ah, 2004), possibly to some extent in response to the Surgeon General s report on bone health that was issued that year. More recently in 2006, it was projected that dietary supplement sales in the United States would approach 5 billion (Anonymous, 2006). While Ca derived from a balanced diet is preferable, Ca supplements are a popular noncaloric alternative for increasing daily Ca intake. There are a vast number of oral Ca supplements available in the market place in the form of capsules, tablets, chewable tablets, effervescent tablets, liquids, powders, suspensions, wafers, and granules. However, not all Ca salts are equally soluble or bioavailable and the dose of Ca on the label of a supplement may not necessarily be reflective of the relative amount of available Ca once consumed. Furthermore, the same Ca salt may be more or less bioavailable depending on the production process and materials used to manufacture the supplement. 

Shown in Figure 10, this ammonia plant is a major part of the overall fertilizer site complex. Other major facilities include urea plant, steam system, and cooling water system. Most of the ammonia is used to make granulated urea product. The other raw material for urea synthesis is C02 from the C02 capture system in the ammonia plant, supplemented with a small stream from an adjacent business. The ammonia production and the C02 available from the ammonia plant are never precisely in balance, in part because of the overall stoichiometric yields of ammonia and C02 from the natural gas feedstock. C02 is the limiting feedstock for the urea plant and its production rate in the ammonia plant sets the urea plant production rate since there is no intermediate C02 storage to buffer the urea production from the C02 production rate. Ammonia that is produced in excess of that which is used to make urea... 

S. E. Pratsinis, et al., Population balance modeling of drum granulation of materials with wide size distribution, Powder Technol., 1995, 82, 37-49. 

Dust Extraction. Adequate dust extraction is necessary to maintain high-speed operation for extended periods of time. The entire compression area should be shrouded to minimize dust infiltration into other press areas. Effective dust extraction minimizes dust and oil contamination on the surface of the tablets, which could produce black specs. Insufficient dust extraction results in excessive material build-up on the lower and upper punches leading to tight punches. However, the proper balance of dust extraction without high levels of material loss must be determined. If the dust extraction level is too high material could be extracted from the die cavities and the recirculation channel. Furthermore, the dust extraction systems preferentially removes the fine particles. Therefore, if the granulation is a direct-compression blend where the active constituent is of fine particle size, minimum dust extraction levels combined with minimal recirculation may be necessary to prevent a loss of active constituents (resulting in possible low assay). 

Psychrometry can be defined as the study of the relationships between the material and energy balances of water vapor/air mixtures. If a system other than air and water is involved, then psychrometry is concerned with the mass and energy balances for the particular liquid(s) and gas(es) at hand. The air/water vapor system is the most common system encountered in the drying of pharmaceutical granulations, but the air/ethanol or air/ethanol-water sy.stems are also frequently encountered. 

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