Time for New Rules in Vacuum Drying: Planex System®, the Brand New Horizontal Paddle Vacuum Dryer, Designed and Patented by Italvacuum

Italvacuum, one of the most important manufacturers of vacuum dryers and vacuum pumps for the main production processes of chemical and pharmaceutical industries, which has since 1939 been involved in developing original and innovative products, has designed, patented and manufactured a new horizontal paddle vacuum dryer called Planex System®.

Planex System (Patent N° US 5,857,264) is a new concept multi product dryer, developed for vacuum drying of wet powders obtained from centrifuge or filter press, and it is based on an innovative philosophy of working, especially suitable for the production of active pharmaceutical ingredients (API), fine chemicals and intermediates.

Planex System consists of a fixed cylindrical chamber with an eccentric agitator inside with two independent movements, able to rotate on its own axis and tangentially to the cylindrical chamber as well. The double combined rotation allows an optimal mixing of the product, continuously renewing the surface of the mass exposed to evaporation, covering all the volume of the vessel. In this way solvents release is facilitated and drying times are significantly reduced compared to conventional systems.

The two movements of the agitator, axial and planetary can either be clockwise or anticlockwise. Every movement combination can be achieved (even not synchronous).
The peculiar configuration of the agitator, characterized by a diameter much smaller than the one of the drying chamber, and the double rotation not only allow the continuous revolution of the product but also limit the mechanical and thermal stress, preventing local overheating due to friction. This enables even more delicate and thermo sensitive products to be treated, as it preserves their purity, avoiding degradation of the dried batch.

It must be remarked that the mechanical stress on the product is about three times less than the one obtained with traditional dryers that are equipped with a concentric agitator. Consequently the overheating of the product, deriving from mechanical action, results considerably lower¹.

Furthermore, the reduced gap between the agitator profile and the wall of the drying chamber avoids deposition of the product and makes the unloading operation extremely easy and effective, being also foreseen a specific program automatically managed.

For the parts in contact with the product Planex System is built in stainless steel AISI 316L, but on request it is available in any other weldable metal (for instance ALLOY C-22 and AISI 904L). The wall of the drying chamber, the back cover, the shaft of the agitator and the front door are heated through diathermic liquid circulation in order to avoid cold areas which could cause solvent condensation or product aggregation.

All the internal surfaces of the drying vessel are mirror polished or electropolished in order to optimise the endurance against corrosion, and reduce the adherence and the friction on the product, increasing the flow behaviour of the powders and simplifying the cleaning operations.
The shaft of the agitator is complete with a double mechanical seal system, studied to guarantee the perfect vacuum tightness and the absolute purity of the dried batch, avoiding any risk of contamination of the product. The mechanical seal may be of conventional type with wet flushing or run dry with nitrogen immission.

The ease of the inner cleaning is granted by an efficient C.I.P system that allows a complete washing of all the parts in contact with the product, while the big front port makes the inspection simple and practical. The SWAB TEST execution is facilitated thanks to the profile of the misaligned agitator and the easy dismantling of its inner parts, unlike in the traditional systems where the paddles can not be disassembled.

The exterior of Planex System can be cleaned as easily as the interior. In fact, the sealed external cladding (particle-free configuration cGMP) covers the insulation material, the electric wiring and the hydraulic piping. There is no support frame in the sterile room, but only the drying chamber flanged to the wall. In this way the external cleaning becomes very easy and effective, avoiding accumulation of the product in recessed areas. These features, combined with the partitioning solution, allow clean room installation, achieving the pressurization and separation of the sterile room from the machine room.

Planex System presents a high loading flexibility. It is manufactured with total volumes ranging from 300l to 4,800l. The loading capacity is function of the treated product and it can vary from 15% to 80% of the vessel volume. Both small and big batches can be treated, covering all the requirements of the chemical and pharmaceutical industries.

Planex System is absolutely safe for the personnel, the environment and the product, as it was designed and manufactured in compliance with the ever-more-severe cGMP and ATEX rules.

Besides the Planex System, Italvacuum also provides all the necessary fittings that complete the plant and that are suitably sized in order to satisfy every process requirement:

  • Heating and cooling group for the system thermoregulation
  • Condensation vacuum group with tank for the recovery of extracted solvents
  • Safety external filtering unit
  • High vacuum group (SAURUS939 pump)
  • Control panel with PLC for the management of operative parameters of the drying process, provided with software which could be certified according to title CFR 21 – Part 11, and able to ensure reproducibility of the dried batch and connectable to centralized supervision systems

Advantages

  1. Absolute safety for the personnel, the environment and the product according to cGMP rules
  2. Perfect homogeneity and uniformity of the dried batch, obtained through the controlled action of the agitator that enables a full revolution of the product, avoiding overheating and degradation
  3. Mechanical and thermal stress is three times less compared to traditional dryers provided with a concentric agitator
  4. Easy and complete unloading of the product thanks to:
    a) profile of the eccentric agitator,
    b) reduced gap between the agitator profile and the wall of the drying chamber (less than 2mm),
    c) specific unloading program managed through PLC
  5. Reduced drying times thanks to the double combined rotation of the inner agitator that increases the product surface submitted to evaporation
  6. Possibility to adjust the speed of the two independent movements of the agitator in both directions (clockwise / anticlockwise) through frequency converters, in order to adapt it to the characteristics of the product and the process
  7. Reduced power consumption
  8. Extremely high final vacuum values (under 0.01mbar) and very low final moisture values
  9. Ease of washing thanks to an effective C.I.P system that enables the liquid to circulate in every point of the drying chamber, allowing to reach residual p.p.m requirements with very few rinsing operations
  10. Ease of inspection to every point of the drying chamber thanks to the configuration of the misaligned agitator and the easy dismantling of its parts, that facilitate the SWAB TEST execution
  11. Ease of external cleaning thanks to:
    a) the complete outer cladding,
    b) the absence of supports of the drying chamber to the floor,
    c) the possibility of clean room installation allowing the separation of the machine room from the sterile room (particle-free configuration)
  12. FDA validation and approval
  13. ATEX certification

¹Analysys of “Politecnico di Torino” University – Material Science and Chemical Engineering Department.

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