DRYING EQUIPMENTNOOR MUHAMMAD SYAHRIN BIN YAHYA

INTRODUCTION

• The wide variety of materials that are dried in commercial equipment and many types of equipment that are used; there is no single theory of drying that covers all materials and dryer types.

• Variations in shape and size of stock, in moisture equilibria, in the mechanism of flow of moisture through the solid and in the method of providing the heat required for the vaporization-all prevent a unified treatment.

• General principles used in a semi quantitative way are relied upon. Dryer are seldom designed by user but bought from companies that specialize in the engineering and fabrication of drying equipment.

INTRODUCTION

• Many type of commercial dryer available in the market, only a small number of important types will be considered in herbal industry.

• The first and larger group comprises dryer for rigid or granular solids and semisolid pastes; the second group consists of dryer that can accept slurry or liquid feeds.

• Typical dryer for solids and pastes includes tray and screen-conveyor dryer for materials that cannot be agitated and tower, rotary, screw-conveyor, fluid-bed, and flash dryer where agitation is permissible, In the following treatment these types are ordered, as far as possible, according to the degree of agitation and the method of exposing the solid to the gas or contacting it with a hot surface, as discussed at the beginning of the chapter.

INTRODUCTION

• The ordering is complicated, however, by the fact that some of dryer may be either adiabatic or non-adiabatic or combination of both.

• Adiabatic:

• An adiabatic process is one in which no heat is gained or lost by the system. The first law of thermodynamics with Q=0 shows that all the change in internal energy is in the form of work done.

INTRODUCTION

• In this chapter will be considered a numbers of related topics, such as Tray dryers, screen-conveyor, tower dryer, rotary dryer, and screw-conveyor dryer, fluid-bed dryer and flash dryer. Furthermore, brief description on a few types of dryer evaporate solution and slurries entirely to dryness, by thermal means, Typical examples are spray dryer, thin-film dryer, and drum dryer.

TYPE OF DRYER USE IN HERBAL INDUSTRY

1. Spray Dryer

2. Fluidized Bed Dryer

3. Vacuum Belt Dryer

4. Freeze Dryer

5. Vacuum Tray Dryer

SPRAY DRYER• Spray drying is a commonly utilized

method of drying a liquid feed through a hot gas for particle formation and drying.

• Spray dry produce powder with a specific particle size and moisture

• Method of producing a dry powder from a liquid or slurry by rapidly drying with a hot gas (steam).

• Spray drying often is used as an encapsulation technique by the food and pharmaceutical industries.

SPRAY DRYER PROCESS

• Liquid feed is pumped through an atomizer device that produces fine droplets into the main drying chamber.

• Atomizers vary with rotary, single fluid, two-fluid, and Ultrasonic Nozzle designs.

• These different styles have different advantages and disadvantages depending on the application of the spray drying required.

• In some instances a Spray Nozzle is used in place of an atomizer for a different dispersion rates.

FLUIDIZED BED DRYER• Fluidized bed dryer consist of a steel shell of cylindrical or

rectangular cross section.

• In this type of dryer, the drying gas is passed through the bed of solids at a velocity sufficient to keep the bed in a fluidized state.

• Process mixing and heat transfer are very rapid in this type of dryers.

• Fluidized bed dryer are suitable for:

1. Granular materials.

2. Crystalline materials.

• If fine particles are present, either from the feed or from particle breakage in the fluidized bed, there may be considerable solid carry over with the exit gas and bag filters are needed for fines recovery.

FLUIDIZED BED DRYER PROCESS

VACUUM BELT DRYER• Can use for all plant extract.

• Suitable for sensitive components such as vitamin & minerals.

• Well preserve during the drying process, because the temperature is not to high.

• Recommended for expensive extract and products, to protect the active ingredients from damage.

VACUUM BELT DRYER

FREEZE DRYER• Fresh or cooked foods are placed in the

dryer where they are frozen to -40 degrees Fahrenheit or colder.

• Once the food is frozen, the freeze dryer creates a powerful vacuum around the food. Then, as the food is slightly warmed, the ice transitions into vapour and evaporates.

• The freeze-dried food is then sealed in moisture and oxygen-proof packaging (Mylar bags, mason jars, or cans) along with an oxygen absorber to ensure freshness until opened.

FREEZE DYERAPPLICATION

• Pharmaceutical and biotechnology

• Pharmaceutical companies often use freeze-drying to increase the shelf life of the products, such as live virus vaccines, biologics and other injectable.

• By removing the water from the material and sealing the material in a glass vial, the material can be easily stored, shipped, and later reconstituted to its original form for injection.

• Another example from the pharmaceutical industry is the use of freeze drying to produce tablets or wafers, the advantage of which is less excipient (added ingredients) as well as a rapidly absorbed and easily administered dosage form.

FREEZE DYERAPPLICATION

• Food and agriculture-based industries

• Because of its light weight per volume of reconstituted food, freeze-dried products are popular and convenient for hikers.

• More dried food can be carried per the same weight of wet food, and remains in good condition for longer than wet food, which tends to spoil quickly.

• Instant coffee is sometimes freeze-dried, despite the high costs of the freeze-driers used. The coffee is often dried by vaporization in a hot air flow, or by projection onto hot metallic plates.

• Freeze-dried fruits are used in some breakfast cereal or sold as a snack, and are a popular snack choice, especially among toddlers, pre-schoolers, hikers and dieters, as well as being used by some pet owners as a treat for pet birds. Most commercial freezing is done either in cold air kept in motion by fans (blast freezing) or by placing the foodstuffs in packages or metal trays on refrigerated surfaces (contact freezing).

VACUUM TRAY DRYER• Same application as vacuum belt

dryer.

• Suitable for sensitive components such as vitamin & minerals.

• Small equipment compare to vacuum belt dryer.

• Preserve the sensitive extract or products during drying process.

• Fast the drying process.

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