Each product to be mixed poses its own individual requirements with regard to technical processing. The example of a medium-sized drug manufacturer in the south of Germany shows that extraordinary process solutions are required again and again. An application-specific machine for the production of an inorganic substance in powder form with a special hydrate level was recently built for this customer.
The author: Dr. Thomas Meyer Laboratory Manager, Gebr. Lödige Maschinenbau
The concrete task in the production of highly efficient preparations is the ability to dry the aqueous solution of an inorganic substance to achieve a powder. A further challenge is to maintain a precisely defined residual moisture in the final product, in other words a specific hydrate level; this requires the product temperature to be kept low throughout the entire process. Based on a demanding test series in the company’s own laboratory, Lödige has developed a tailor-made process solution for this complex step.
Test series on laboratory scale
The heart of the Lödige concept is a horizontal dryer that has proven itself in similar situations. However, the first trials with the product in a machine of similar design failed. The material to be mixed had a high level of adhesion to the drum wall and the mixing tools, calling for very high input power. The residual material discharge also proved difficult, because at the end of the drying phase, the aqueous solution had not only vaporised into powder but also formed lumps as a result of adhering material breaking loose. Lödige therefore carried out extensive test series with a 5 l laboratory dryer to optimise both the equipment and the process control and enable suitable conditions to be defined. During these tests, the temperature of the drum’s heating jacket and the starting product was varied. A relatively low product temperature and a high vacuum were ultimately determined as ideal process conditions. There was almost no material adhesion. On this basis, it was possible to develop a customised process recipe that allows a fully automatic drying sequence without manual intervention.
Customised solution and scale-up
Taking these findings as a starting point, Lödige planned and realised a 20 l machine with all peripheral equipment. The machine is subdivided into two modules: a main section encompassing the horizontal dryer and a processing module comprising a vacuum pump, condenser, air treatment, etc. It goes without saying that the separation into production and technical areas which is obligatory in a pharmaceutical facility was also taken into consideration. For this reason, a stainless steel wall partitions the clean room side off from the mechanical equipment on the technical side.
The complete machine, including all its individual components, is certified according to the applicable pharmaceutical directives (EU-GMP or FDA). Apart from the separation of the production and technical areas, this chiefly means that, due to the fact that the product is highly efficient and hence toxic in its pure form, there must be no contact between the operator and the product in the production area. This is why the machine guarantees not only a clean supply of raw product but also dust-free discharge. The production process additionally necessitates automatic cleaning in place (CIP) and sterilisation following each batch.
Last but not least, the machine is equipped with a PLC-based, step-by-step control system with a recipe mode. The system allows any number of recipes with an almost unlimited number of process steps to be stored for this type of control. The required production recipe is downloaded from the recipe manager into the programmable controller (PLC) and processed precisely. The entire process is automatically documented together with all events and intended, permissible intervention in the recipe sequence. The machine comes with a touch display for local control and operation, but can also be controlled externally from a remote location.
To ensure the best possible performance of both the machine and the peripheral equipment, the drying process was optimised during commissioning on site and adapted to the conditions in the plant. Production was validated on the basis of three batches. In case of future conversions, the dryer can, of course, be used to process other products with similar properties and processing requirements.
Online-Info: www.cpp-net.com/2211452
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