FOOD TECHNOLOGY

FT31 Fluidised Bed Drier - Provisional

The Laboratory Fluid Bed Drier has a number of significant advantages when compared with conventional drying techniques.

Order Specification |
Capabilities |
Description |
Experimental Work |
Technical Specification

Requirements |
Shipping Specification and Dimensions

ORDERING SPECIFICATION

• High rates of heat and mass transfer
• Drying and residence times from a few seconds to a few minutes
• Materials with moisture contents to over 80% may be dried
• Ambient to 100°C drying air temperature range
• Wide range of materials can be processed
• Processes other than drying investigated, e.g., mixing and blending of solids, size reduction, agglomeration and granulation, classification into sizes and cooling of particles
• Wide range of materials can be dried from fine powder to slurries and pastes
• Heat sensitive food stuffs may be dried
• Compact and portable
• Air drawn through mesh filter by centrifugal fan over a 2kw heater and through a stainless steel filter gauze
• Blower controller by a thyristor circuit
• Readings displayed by digital meter
• Manual or interval timing control 0 - 10 minutes
• Filter bag to retain stray particles
• Power consumption: 3kw
Temperature range: 20 - 100°C (±1°C)
Maximum sample weight: 5kg

capabilities

> high rates of heat and mass transfer

> drying times and terefore residence times range from a few seconds to a few minutes - often less than 15 minutes are required for complete drying

> materials with moisture contents from a few percent to over 80 percent may be dried

> the drying air temperature range is ambient to 100°C which covers the majority of drying operations

> a wide range of materials can be processed including organic and inorganic compounds, pharmaceutical chemicals, foods and fuels, minerals and agglomerating materials

> in addition to drying, other processes may be investigated e.g. mixing and blending of solids, size reduction, agglomeration and granunlation, classification into sizes and cooling of particles

The drier can be used with a wide range f materials including fine powders, coarse particles, crystals, granules, even slurries or pastes (after decanting or pre-drying or by spraying into an initial bed of the dried material).

Heat sensitive materials including foodstuffs like peas, wheat or lentils may bedried at relatively low temperatures

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Description

The drier is of simple, compact design, conveniently portable and easy to operate, the only requirement being a mains power supply.

Air is drawn through a mesh filter in the base of the cabinet and blown by a centrifugal fan over a 2kW finned electrical heater and through a stainless steel filter gauze before being delivered to the distributor gauze at the base of the drier body which supports the bed and distributes the air uniformly.

The air blower is controlled by a thyristor circuit to give a smooth vibration over a wide range of motor speeds, enabling efficient fluidisation to be achieved for a variety of materials and giving fine control of the drying temperature. Readings are selected and diplayed using a digital meter. The unit can be manually operated or interval timing can be carried out with the timer unit, which gives a 0-10 minute timing range and an alarm facility to notify completion of the operation.

The tube unit locks into position on the cabinet top by a simple bayonet fitting and the base of the tube is removeable to allow replacement of the distributor gauze. A filter bag is employed to retain any stray particles of the sample being fluidised, allowing the passage of the exit gasses.

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Experimental Work

> simple drying of a material to give moisture content and the drying time (or residence time) required

> determination of drying curves to assess the feaseablity of fluidised bed drying of a material on an industrial scale. Drying curves are rrelevant to the mechanism of drying - they may be used as a basis for heat and mass balance, thermal efficiency of drying and drier design

> calculation of heat transfer coefficients for different conditions - important in drier design and comparison of fluidised beds with other drying methods

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