When producing active ingredients for pharmaceuticals, first class product quality is essential. Therefore, the processes and equipment used have to meet the highest standards.

Glatt GmbH Process Technology in Binzen near Lörrach produces production systems in accordance with the fluidised bed process with which in addition to other applications it is possible to create the bases for tablets.

In this process, starch particles are placed in a reaction container to which an air flow is applied from below causing the particles to swirl around. An accurately metered amount of solvent containing the active ingredients is then sprayed into the reaction area and thus within half an hour to three hours, the active ingredients will be deposited on the vehicle. If a round compact product shape is required, the floor of the reaction container can be designed as a turntable on which the granulate grinds itself into a round shape during the structuring process.

Due to the environmental regulations which are becoming more and more restrictive, the solvent may no longer be emitted which means that this material has to be recycled. This can be attained by absorption, adsorption as well as by means of thermal or catalytic combustion. Dust emissions can be prevented through waste air filter systems.

During the production process static charges can occur. Therefore, especially when using combustible solvents, an explosion protection is necessary. This can be achieved by means of a two bar pressure resistant design, as well as through an immediate cutting off of the reaction container.

So that the process only takes a short time, the vacuum fluidised bed process was developed. Through low pressure in the reaction container the evaporating temperature of the solvent drops so that even heat sensitive products can be processed independent of the atmospheric influences. A complex inertising system with oxygen monitoring for explosion protection is not required in this case.

The substances can only be created homogenously if all the process parameters are accurately upheld. An essential factor in this case is the size and the consistency of the air flow. When the flow speeds are too low, optimal swirling is not possible, if on the other hand the air circulation is too strong, the granulate bursts when it comes into contact with the walls of the container.

To measure the volume flow of the incoming air of the reaction container, FA windmill type anemometers made by Höntzsch in Waiblingen are used in different versions.

The measurement principle is based on the fact that a vane adopts a speed proportional to the flow speed present. An inductive proximity switch whose oscillator coil generates an electrical field, records the vane speed. When the tip of the vane enters this electrical field, an oscillating circle is dampened and a pulse is generated. The electrical pulses generated in this way are passed on to the respective evaluation unit where they are for example converted into a linear speed display strictly proportional to the pulse frequency. The robust design of the sensor guarantees a long service life which is a precondition for a smooth production process.