Romaco has developed a new generation of nozzles for granulation using the fluid bed process. The new FLEXIJET® offers easy operation, fast cleaning and low-cost maintenance. It is therefore the perfect choice for short granulation processes. Its predecessor, the ROTOJET®, is still recommended as a special nozzle for coating processes that take several hours and use unstable suspensions.
In the fluid bed process, the spray nozzle plays a crucial role. Its task is to introduce the spray liquid into the fluidised product and either granulate or coat the powder, depending on which process is required. With the FLEXIJET®, Romaco Innojet is launching a nozzle technology that has been specially developed for fluid bed granulation, with a focus on simple handling and easy nozzle cleaning. Granulation demands considerably less time than fluid bed coating processes, which is why the spray nozzles used for granulation have to be dismantled and cleaned quite often. The FLEXIJET® was therefore designed specifically with short batch processing times and frequent product changes in mind. To remove the nozzle, all that’s needed is to undo one screw; it can then be detached and dismantled into its ten individual parts. Refitting cleaned components is also extremely simple and can be completed very quickly without checking and adjusting the spray gaps.
This new, simpler handling is partly due to the design of the spray gap, in which a flexible plastic membrane seals the circular gap from above. The flexible cap lifts solely through the pressure of the incoming liquid and ensures excellent distribution even at low spray rates. If the process has to be interrupted, the spray liquid is pumped back, causing the membrane to be sucked in and to securely seal the spray gap. This prevents the gap from drying out and deposits from forming, which could block the nozzle when the machinery is restarted and therefore put the process at risk.
Maintenance of the FLEXIJET® is also easier because all nozzle components and wearing parts are available to reorder at any time and can be replaced by users themselves. This is what makes the FLEXIJET® so different from its predecessor, the ROTOJET®, a sophisticated precision tool in which the manufacturing tolerance spans a chain of more than 20 components. Use of the ROTOJET® therefore requires far more specialist knowledge than operating the new FLEXIJET® spray nozzle.
Specialist for unstable suspensions
The ROTOJET® spray nozzle is preferred for functional coating processes and for coating fine starter particles with pharmaceutical ingredients. Coated micropellets are needed to manufacture MUPS tablets, for example. While the coating process can take several hours – a production time of over 20 hours is no rarity – the pellets significantly increase in weight and also multiply in diameter.
This highly complex production process demands exceptional precision coupled with a very tightly controlled process, especially when working with unstable suspensions that have a tendency to segregate. To minimise the risk of sedimentation during the spraying process, the ROTOJET® has been equipped with a rotating nozzle head. This rotation produces a relative motion in the spray gap, which continuously moves and mixes the spray liquid. This prevents the formation of deposits that would block the nozzle and result in unwanted agglomeration. Consequently, successful micropellet production using the fluid bed method requires a high-precision tool with fairly challenging operation and maintenance procedures.
A less complex spraying tool
Romaco Innojet has developed the FLEXIJET® spray nozzle as an alternative to the ROTOJET®, so that the spraying process can be adapted to specific products. From now on, users can select the nozzle type that best suits their process. To enable easy switching between the two nozzles, care has been taken to ensure compatible mounting dimensions and an identical spray geometry. This way, the nozzles can be operated with the same process parameters, without the need to adapt or convert anything on the machine. Both spray nozzles are available for all VENTILUS® fluid bed processors – from the lab to the pilot all the way to full-scale production. Besides granulation, the FLEXIJET® nozzle is also recommended for hot melt coating applications, as no liquid evaporates here and batch processing times are relatively short. The new, patented nozzle technology has already proven its worth in practice and is used by German and French pharmaceutical manufacturers, among others.
One nozzle for all situations
It doesn’t matter whether one uses the FLEXIJET® or the ROTOJET® – all sizes of all VENTILUS® machines are operated with one centrally positioned bottom spray nozzle. It is located in the centre of the ORBITER® booster plate, which lets in process air and ensures uniform flow conditions in the cylindrical process container. At the same time, the booster’s circular shape and overlapping vanes cause the product to move in a donut-type pattern. This produces a tightly controlled particle motion and enables exceptionally homogeneous product spraying and drying.
Both spray nozzles feature three circular spray gaps arranged one above the other. The liquid is sprayed horizontally at a 360° angle through the central gap into the product. Meanwhile, compressed air is introduced via the upper and lower air supply gaps, atomising the liquid into minuscule droplets. The size of these droplets depends on whether the product is to be granulated or coated, and is determined by the pressure at which the upper and lower spray jets hit the spray liquid. Once these parameters have been defined for a specific process, it works regardless of which nozzle technology has been selected.
The tried-and-tested Innojet design, with just one nozzle for every scale, already makes it easier to control the fluid bed process. Now, the introduction of the new FLEXIJET® nozzle has additionally reduced the complexity of the spray gun. This new, user-friendly design pays off: low maintenance costs, stable processes and high yields are all testament to the innovative nozzle technology.
Find out more by visiting Romaco at POWTECH TECHNOPHARM 2026 from September 29 to October 1 in Nuremberg (Germany), Hall 9, Stand 9-241.
At this trade fair, Romaco will be presenting its complete portfolio of processing solutions, including the VENTILUS® Lab fluid bed processor and the KTP 1X compaction simulator, which will both be on display.
For more information on Romaco, visit our website and social media channels: www.romaco.com
