Vacuum Tray Dryers

FUNCTION

Used mainly for drying of high grade, temperature and oxygen sensitive products. 
Highly suitable for drying hygroscopic substances, which are dried to very low residual moisture, content level. Frequently vacuum drying cabinets are the sole possibility for drying lumpy, glutinous products or products of low pompality.

CAPACITY

Standard models range from 4 trays to 48 trays. 

SALIENT FEATURES

Bodies may be of cylindrical or rectangular cross section. Both shelves and body are heated ( the body to prevent internal condensation) with controlled circulation of hot water, steam or diathermic fluid. Vacuum is drawn through large diameter ducts to minimize pressure drops and produce minimum working pressures. Both rotary and static dryers can be supplied with the following Optional ancillaries :

A) heater system for either pressurized hot water or diathermic fluid;
B) cyclones and sleeve filters for powder recovery (for rotary dryers);
C) solvent recovery system with condenser and receiver; vacuum pump and ancillaries: characteristics and dimensions depending on the drying processes.

Vacuum Tray dryer is the most commonly used batch dryer. They are box-shaped and loaded and unloaded via a door (two doors on the larger models). Inside are several heating plates mounted one above the other on which the product is placed in trays. The bottoms of both heating plates and trays should be as smooth as possible to permit optimal heat transfer between plates and product. The medium flowing through the heating plates is water, steam or thermal oil. The distance between the heating plates is determined primarily by the surface loading and the foaming of the product. To avoid retrograde condensation the cabinet walls are indirectly preheated by the heating plates. Next, the product is introduced and heated at atmospheric pressure. Only after all individual product trays reach the same temperature the cabinet is evacuated and drying can start. The  preheating phase is very important in order that the drying curve and the foaming of the product is identical throughout the cabinet. During the main drying phase the vacuum is in the range of 40 to 80 mbar abs and in the final drying phase vacuums of only few mbar abs are reached. Heating temperatures are normally in the range between 800C and 1100C. Depending on product and surface load, drying takes from a few hours to 1 to 2 days. For some products the vacuum and temperature profiles are automatically controlled in order to prevent a pass over of the critical product temperature.

The dimensioning of the vacuum system is an important factor in the design of drying cabinet systems. If for example vigorous foaming of the product is desired, evacuation to the operational vacuum level must take place very quickly. Vapours produced during drying are taken out direct, or via a steam jet compressor to a surface condenser in which the vapours condensate. The non-condensable vapours are extracted by the vacuum system.

On completion of the drying, the product can be cooled by circulating of cooling water through the heating plates.

Often vacuum drying cabinets are supplied to new, small production operations in newly opened markets. Following successful development of the market, it could be worthwhile to replace the cabinets through continuous vacuum belt type dryers.

In other applications products with many formulations are manufactured in parallel production lines and the use of continuous vacuum belt dryers is out of the question because of the small production batches.

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 Double Cone Dryer

Special Features

Multi product, easy to clean, internal filter.

Easy openable charging port. Self cleaning butterfly discharge valve for total discharge of the product.

The unit is complete with :
Internal powder filtration unit, solvent recovery unit, heater / cooling inlet & outlet unit, ecological high vacuum unit & control panel unit.

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 Vacuum Dryer With Mechanical Rake 

FUNCTION

To dry heat sensitive and air sensitive material under vacuum thus accomplishing the drying at moderate temperature avoiding contact with air.

CAPACITY

5 litres onwards (Chamber Size)

SALIENT FEATURES

The entire drying chamber is well machined to bring about a close encounter with the agitator blade thus ensuring proper shuffling of the material and thus avoiding localised over heating. The leak proof front opening door ensures easy cleaning of the entire chamber. 

The top loading and bottom unloading facility provides for easy charging and discharging of the material. The cyclonic trap prevents the fine dust of the dry material from flying into the vapour condenser. The condenser and the condensate collection tank prevent the vapours from entering the vacuum pump. Appropriate vacuum pump and accessories are provided with the unit with valves to adjust the right vacuum in the unit. The entire unit is mounted on a steel frame. 

They are used with particular success in agglomeration  free rapid drying, heterogeneous reactions with systems of different substances, sterilization and in general for vacuum application. Heating arrangement can also be provided along with the unit.

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 Fluid Bed Dryer

FUNCTION

To dry material by fluidisation with hot and / or dehumidified air.

CAPACITY

5 to 300 Kgs.

SALIENT FEATURES

The atmospheric air is sucked in the dryer through 5 / 10 micron filter by an efficient dynamically balanced fan driven by an electric motor. The clean air then passes over the electric heaters/ steam or oil radiator provided with temperature controller. The hot air passes  through the product and fluidisation dries the product. Dryer is provided with dehumidifier (Chilled water system) at the inlet of the dryer so as to dry the product at low temperature under fluidized condition. The blower speed is controlled by A. C. frequency drive so as to control the fluidization avoiding choking of the filter bag. A raking system provided to avoid lump formation in the container to achieve uniform fluidisation & uniform drying. A model with complete automation and PLC, automatic bag shaking and with mimic is also offered.

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 Rotary Dryers

In direct heat rotary dryers a continuous feed of wet particulate material is dried by contact with heated air, while being transported along the interior of a rotating cylinder, with the rotating shell acting as the conveying device and stirrer.  We offer rotary dryers in co-current (parallel) and counter-current operation.  In the former the wet material is exposed to the hottest air, which enables heat sensitive or sticky materials to be dried successfully. In the counter-current operation dried material is exposed to the hottest air helping to achieve very low moisture content.  The hot gases may enter the dryer at very high temperature.

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