Drying / Lyophilisation

Vacuum belt dryer

Liquid products are uniformly distributed on the belts with swivel feeders.

Free flowing powders, granules and products of larger sizes are conveyed into a hopper on top of vacuum belt dryer. By interval the product is fed into an intermediate chamber under vacuum from where the product will be loaded onto the top belt by a special rotary dosing system.

Liquid or pasty products will be conveyed through the dryer with in parallel operating belts. Solid products are transported back and forward through the dryer from the top to the bottom belt in order to extend the residence time.

The heating plates underneath the belts are installed in independent heated zones to permit constant or variable drying rates. This allows gentle continuous drying for maximum product quality. The last zone can be designed as a cooling zone if required.

At the end of the belt the dried product is cut to the desired size by a guillotine type breaker bar and a crushing device. The product is collected in an intermediate hopper from where it is discharged out of the vacuum into the atmospheric environment with alternating pressures. The removed vapours are recovered in a condenser. The vacuum is maintained usually by liquid ring pumps and single or multistage steam jets.

Vacuum drying cabinet

Vacuum drying cabinets are worldwide the most used contact dryers working in a batch mode.

They are designed to contain several rectangular, horizontal installed heating plates arranged one above the other with a minimum of dead space. By implementing a vacuum system the drying process can be carried out on low temperatures maintaining the maximum product quality of the dried products.

On customers request Bucher delivers also all peripheral equipments required for the drying operation such as vacuum pumps, condensers, heating and cooling systems and as well control systems.

Bucher DryCab drying cabinets are also available in special execution upon customer demand.

Zeolite reactors for the gentle vacuum drying or vacuum freeze drying of products by mean of water adsorption

The Bucher Zeodration system uses Zeolite reactors to trap the water or solvent. Zeolite is crystallised clay with a pore diameter of 4 Angstroms (water molecule are 3 Angstroms). Its properties, combined with polarity factors lead to a selective moisture trap which under operating pressure conditions retains water only. Because of a very low partial pressure at the water adsorption a maximum reduction of lost volatile molecules through the vacuum system is achieved, thus maintaining most of the flavours in the product.

While using Bucher Zeodration with vacuum driers the same product quality can be achieved than with freeze drying systems. Due to an integrated and cyclic regeneration of the Zeolite the full adsorption capacity is maintained.

The application of zeolite reactors offers interesting features as it permits a drying operation in the pressure range of 0.5–10 mbar (range limit to freeze drying).

Zeodration can be combined with a Bucher vacuum cabinet dryer for batch production or a Bucher vacuum belt dryer for continuous production.