FLUID BED DRYER

FLUID BED DRYER :

Fluid bed dryer works on a principle of fluidization of the materials. In fluidization process, hot air or gas flow is introduced through the bed of solid particulates. This gas or air will move upwards through the spaces between the particles. As the velocity increases, upward drag forces on the particles increase and at a stage become equal to the gravitational forces beneath. Hence the bed is said to be fluidized and the particles are suspended in the fluid.

There are various advantages of fluid bed dryer in pharmaceutical industries. Some of them are as follows.

Advantages of Fluid Bed Dryer

• High thermal efficiency is achieved when the thermal energy is supplied by internal heat exchanger
• Low Capital Cost
• Ease of Maintenance and Control
• High Heat and Mass Transfer Rates

In a fluid bed dryer used for powder drying, initially the air is sucked inside from the surroundings with a fan run with electric motor inside the dryer. The air then passes through heating system within the dryer and gets heated up. This hot drying air is then made to flow through bed of the moist materials that are laid on shaking perforated steel bed. This air is introduced with required velocity and temperature that the bed gets fluidized allowing intimate contact of each particle with the air. As the bed vibrates or shakes, the particles in the bed are carried forward slowly along the length of the dryer. All the moisture present in particles get sucked by the hot air which then escapes into the dust recovery system and is recycled for the further use in process. The velocity and temperature of air can be controlled as the particles pass on the bed and hence very wet to sticky materials can also be dried with a fluid bed dryer effectively. The dried material is then fed into the cooling zone where cool air reduces the temperature of the material to the required state.

Therefore in this way product or powder drying can be efficiently achieved with the help of a fluid bed dryer.

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• Variable Air handling equipment from the basic, compact pre-filter and heater to the system
• These equipment provide complete control of the condition of the processing air
• Uniform drying and reduction in drying time.
• Involves low labour input.
• To prevent any fine dust to pass through the product, the atmospheric inlet air is filtered by means of single / multi stage filters of 20 microns.
• Steam Coil made out of 1″ dia. SS 304/316 finned tube
• The steam coil is specially designed to get pressure of around 3-4kg./cm^2 (working pressure 3 kg/cm^2)
• A digital temperature indicator cum controller enables in indicating the inlet and outlet air temperature as well as to control the present inlet air temperature
• To control the inlet and outlet air flow air suction and discharge dampers are provided
• To prevent static charge in the machine, an explosion safety flap of adequate capacity at the rear end of the dryer and an positive earthing point timer is provided that sets the process time cutting off the motor supply after pre-set time period.