Drying Extra slides 1 Mahmoud Teaima, Ph.D.. Tray or shelf dryer (hot air oven) It operates by passing hot air over the surface of wet solids in the trays.

DryingExtra slides

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Tray or shelf dryer (hot air oven)

It operates by passing hot air over the surface of wet solids in the trays inside the oven. Thermal efficiency of air is improved by: recirculating the air over the heater 2

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Vacuum Tray Dryer

Heated indirectly by steam instead of hot air.The condenser is placed between oven & vacuum pump WHY? To protect vacuum pump from condensate prevent corrosion. Advantages: 1. Suitable for thermolabile granules. 2. Allow solvent recovery.

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The presence of a double receiver allows continuous vacuum operation.. HOW?

The upper part below the condenser is connected to pump and leads to the lower part by the pass pipe E.

1- On running, E is open and the Condensate drains into the lower receiver.

2- When it is full, E is closed and the vent F is opened to make pressure equilibrium between inner and outer atmosphere. Then, water get out from g.

3- When the drainage of water ends, F is closed and E is opened again so that the condensate collected in the upper part during this short period runs down.

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Freeze Dryer (Lyophilizer)

Sublimation occurs when: The external pressure around ice < vapor pressure water is transferred from the solid to gas form without melting.

RefrigerantDrying chamber

Heater

Refrigerant

Condenser

To high vacuum

Tray

Tray

Refrigerated shelf

Refrigerated shelf

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Refrigerant

Refrigerant

To

hig

h vacu

um

Drying chamber

Heater

Ice

Ice

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Low temperature / high vacuum are suitable for:a. Materials that decompose during normal drying process.b. Materials that change their nature at higher temperature like: 1- Thermolabile materials as protein, plasma, antibiotics 2- Vaccines, tissues, serum.c. Many commercial products when the rapid dissolution or

solubility is so important. Eg. Feldene flash tab, Aspegic vial & liometacin amp.

• Freeze drying is very expensive process so it must be used with expensive thermolabile materials only

*** Zydis is a new technology in preparing fast dissolving tablets developed by RB Scherer.

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Steps of preparing fast dissolving tablets

by Zydis technology: • Mix the active ingredient with certain excipients (like

glycine, mannitol or lactose) in a suitable mixer.• Make a solution or suspension of the mixed

ingredients.• Fill the tablet blister with the solution (suspension)

of the mixed ingredients.• Freeze the solution (suspension) within the blister.• Carry out freeze drying.• Blister lidding.• Final packaging.

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Cyclone separator

Standard Spray Dryer • Hot air is introduced from an upper opening of the drying

chamber giving spiral movement until reaching the bottom (con-current) then passes through a dust separator until reaching the bottom (con-current) then passes through filter sleeves.

• A pressure atomizer is used. The product is: 1. Highly soluble, potent and stable. 2. Have good flow properties.

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