INTRODUCTION:

Drying method is common in the chemical, pharmaceutical and food productions.¹ It has been informed that an ordinary 12% of energy spent it used on drying, and the price of drying could range up to 60-70 % of entire charge of deal.² The particle are fluidized in bed when the drag force created by the gas flow through the bed is equal to the weight of the particles.³ When fluidizations happen, the solid particle has various properties of a fluidized. Single noticeable things are the fluidized particle get to level and assume and figure of holding container. Big weighty thing sink when added to the thing and light particle float.⁴

Fluidized belt have been extensively used in the chemical, pharmaceutical, and food businesses as batch dryer due to their high heat and mass transfer charges as an outcome of high connection between gas and particle in the compartment.^5-6

Effective applications of fluidized belt dryer include drying food creation such as soybean’s, farming product such as paddy and colza, biochemical product such as baker’s yeast, and pharmaceutical material such as dibasic calcium phosphate powder.^2-7-8

Throughout fluidization, air runs through the bed of particles and suspended the particle in the air stream, outcome in a dynamic fluidized identical state for the particles.⁹ When air upward passes through a bed of particle, the compression of supplied air globules due to the growing resistance with increasing air movement. With increasing air flow, an extended bed is obtained with some particle brought up into the air stream. As the upward drag energy keeps increasing with the air flow, finally the mass of particle is counterbalanced, separation of the particles increased and bed is fluidized.^10-11

Principle:

In the fluidized bed dryer warm air is passed through a perforated bottom of the vessel holding particles to be dry. The particles are suspended in the air stream and rise from the bottom. This situation is termed as fluidized state. Hot air bounded each particle to dry it totally. Therefore the constituents or granules are dried consistently.^12-13

Fig. Fluidized Bed Dryer

Construction:

The fluidized bed dryer be made of steel case of tubular or quadrangular cross sector. A removable container which has completed bottom is placed on the bottom of the dryer. It used to load and unload the things. The container is used to place the materials to be dried. A fan is fixed on the top to circulate hot air. The renewed air inlet the pre-filter and the heat exchanger are associated in series to heat the air to essential temperature. The temperature of hot air and the exhaust air are observed. The bag filters are placed on top of the drying vessel for a recapture of the penalties. The air flow is adjusted by means of the recirculation control. The fabric bags are provided to inhibit the passage of the fine particles.^12-13

Working:

The wet particles to be dried are placed in a attachable vessel. The container is implanted in the dryer fresh air can pass through a pre-filter which is then heated when passing through a heat exchanger. Hot air flows through the bottom of the container. At the same time the fan starts to rotate. The air speed increases gradually when the velocity of the air is greater than the sedimentation rate of the particles remain partially suspended in the gas stream.

After a specific period a compression point is touched in which the friction drags on the particle is equivalent to the strength of gravity. The granule’s increase in the vessel due to the high gas velocity of 1.5 to 7.5 m per minute and then fall back. This method is said to be fluidized state. The gas surrounds each particle to dry them entirely. The air comes out of the dryer passing through the filters in the bag. Periodically the bags are shaken to eliminate entrained particles.

The residence time for drying is around 40 min the material is sometimes left in the dryer to touch room temperature. The container is detached for unpacking. The last product is free flowing.^12-13

Advantages of Fluidized Bed Dryer:

1. Smaller drying period

2. Effectively at little temperature

3. Constant drying

4. Drying of single particles

5. Temperature is remain constant

6. Reduce labor, space with extraordinary product.^12-13

Disadvantages of Fluidized Bed Dryer:

1. Various organic precipitate develops electrostatic charges during drying. To avoid this efficient electrical grounding of the dryer is essential.

2. Chances of attrition of some materials resulting in the production of fines.^12-13

Application in Pharmacy:

1. It is used for the drying of the particles in the manufacture of the dosage.

2. It is used for covering of particles.

3. Physical method include drying, mixing, granulation, heating, and cooling

4. These methods take benefits of the brilliant mixing capabilities of the fluidized bed.

5. One of the most important application is to the drying of solids

6. Fluidized beds are often used to cool particulate solids following a reaction.^12-13

REFERENCES:

1. Soponronnarit, S.; Pongtornkulpanich, A.; Prachayawarakorn, S. Drying characteristics of corn in fluidized bed dryer. Drying Technology 1997, 15(5), 1603–1615.

2. Sarker, M.S.H.; Ibrahim, M.N.; Abdul Aziz, N.; Punan, M.S. Energy and exergy analysis of industrial fluidized bed drying of paddy. Energy 2015, 84, 131–138.

3. Kunii D and Levenspiel O 1991 Fluidization Engineering 2nd Ed. (Butterworth-Heinemann London) p 1-92

4. Perry R H, Green D W and Maloney J O 1997 Perry’s Chemical Engineers Handbook (New York: McGraw-Hill)

5. Tatemoto, Y.; Mizukoshi, R.; Ehara, W.; Ishikawa, E. Drying characteristics of food materials injected with organic solvents in a fluidized bed of inert particles under reduced pressure. Journal of Food Engineering 2015, 158, 80–85.

6. Srinivas, G.; Pydi Setty, Y. Drying behavior of uniform and binary mixture of solids in a batch fluidized bed dryer. Powder Technology 2013, 241, 181–187.

7. Hematian, S.; Hormozi, F. Drying kinetics of coated sodium percarbonate particles in a conical fluidized bed dryer. Powder Technology 2015, 269, 30–37.

8. Wan Daud, W.R. Fluidized bed dryers—Recent advances. Advanced Powder Technology 2008, 19(5), 403–418.

9. Heigl, N.; Koller, D.M.; Glasser, B.J.; Muzzio, F.J.; Khinast, J.G. Quantitative on-line vs. off-line nir analysis of fluidized bed drying with consideration of the spectral background. European Journal of Pharmaceutics and Biopharmaceutics 2013, 85(3, Pt B), 1064–1074.

10. Türker, M.; Kanarya, A.; Yüzgeç, U.; Kapucu, H.; Şenalp, Z. Drying of baker’s yeast in batch fluidized bed. Chemical Engineering and Processing: Process Intensification 2006, 45(12), 1019–1028.

11. Ozahi, E.; Hacımurat, D. A model for the thermodynamic analysis in a batch type fluidized bed. Energy 2013, 59, 617–624.

12. Pharmaceutical process engineering, Anthony j. Hickey, David gander ton, volume 112, page no. 101-102.

13. Pharmaceutical process engineering, Anthony J. Hickey, David gander ton, volume 195, second edition page no 79-80.

Received on 12.10.2020 Modified on 17.11.2020

Asian Journal of Pharmaceutical Research. 2021; 11(2):104-105.

DOI: 10.52711/2231-5691.2021.00020