Pneumatic conveying for pharmaceutical powders
When it comes to the production of medicines such as pills, tablets or capsules, the requirements of pharmaceutical companies are very precise and stringent.
The compounds in this sector must comply with the exact percentages of the components and obviously cannot be contaminated by other chemical elements, neither by dust or dirt of any kind.
The pace of production must also be meticulously respected; it is not always possible to run out of a medicine or to rely on stocks, and in such cases, downtime causes double damage.
Last but not least, in the field of pharmacology, there are many different types of production machinery to be supplied, such as blister machines, compactors, operculators, dosing machines, reactors and mixers.
Finally, the requirement to keep clean the working areas, as it is very frequent that the handled substances are not harmless to humans when dispersed in the environment.
Unlike traditional conveying systems, pneumatic conveying is able to respond positively to all these needs, even in the most rigorous cases in terms of required operating parameters.
For the designers of pneumatic conveying systems dedicated to active pharmaceutical substances, the most challenging part is certainly that of calibrating the systems, so that the handling of powders composed by several components with different specific weights does not alter their homogeneity.
Even intuitively, it’ understandable that, without proper design, sucking or pushing a multi-component powder into a pipe will cause heavy and light particles to assume different velocities. The risk is that on arrival the medicinal powder will have a different dosage than at departure.
Our customer approached Apply with the need to connect a biconical mixer, in which the active ingredients are mixed in powder form by rotation, with a compressor, i.e. an automatic machine that continuously compacts the pharmaceutical powder into tablets.
Handling of mixed powder used to be done by hand, with all the disadvantages this entailed.
A pneumatic conveying system for pharmaceutical powders made it possible to improve hygiene standards even more, increase the speed of the line, monitor production progress, work non-stop for very long periods of time, eliminate downtime and also reduce the human presence in such a sensitive production.
The project
Apply’s designers created a dense phase pneumatic conveying system that brings the pharmaceutical powder to its destination not directly, but via an intermediate stage.
From the biconical mixer, the active ingredients are first stored in a bin, i.e. a closed 316L stainless steel container with a capacity of 250 kg, and then transported to the compressor.
The transit through the bin is necessary because its capacity ensures that the compressor always has enough pharmaceutical powder to run without stoppages, which would not be the case with direct suction from the bicone.
Thanks to two vacuum hoppers, one installed on top of the bin and one on top of the compressor, the pharmaceutical powder can cover the two sections of the required route, travelling through closed pipes, also made of stainless steel and with non-toxic and anti-static flexible pipe ends.
Let’s take a look at how this pneumatic conveying system works.
The bicone is loaded with all the individual active components and makes a fixed number of rotations, following the recipe, then it stops.
At this point, the hopper on top of the bin starts working and loads the product, sucking it from the mixer thanks to the vacuum created by the vacuum pump. When the hopper reaches the full level, it stops suctioning, discharges the pharmaceutical powder into the bin and automatically cleans the filter inside.
The second part of the journey is carried out in the same way.
Special features of the pneumatic conveying system
There are three interesting points to note about this pneumatic conveying system for pharmaceutical powders.
We said that the pharmaceutical powder is sucked into the hoppers by the force of the dry vane pumps. This force and the diameter of the pipes are calibrated in such a way that the product is taken from the bicone and bin not continuously but in blocks.
In this way, product clusters travels through the pipes, interspersed with air-filled spaces. It is precisely this mode of operation that guarantees the integrity of the powder, which will arrive at the compressor with the unchanged percentages of each individual component, just as they were at the twin cone.
If you vacuumed continuously, the powder would be whirling along the way and would be demixed on arrival.
The second point concerns the air fed into the system. In order to move the pharmaceutical powder smoothly and flowingly through the pipeline, it is essential to introduce a minimum amount of air, which is the reason this pneumatic conveying system is described as closed. The air is introduced by a small fluidisation apparatus with valves, installed at the bicone and the bin.
This air does not contaminate the product in any way. In fact, the level of air purity in our customer’s plant is extremely high, even with temperature and humidity control, and there is additional filtering at the exit of these valves.
Finally, a design note. The pneumatic conveying system for pharmaceutical powders that we created is not used for a single recipe but, according to needs, it can handle different active ingredients for different pills.
At each changeover all the elements of the system must be cleaned and washed either manually or in an autoclave.
In order to keep disassembly and assembly time to minimum, we designed the all project with quick releases, few components and steps that are absolutely intuitive for the operators.
Strengths of the pneumatic conveying system for pharmaceutical powders
- Simple and fast installation
- Intuitive disassembly and assembly
- Totally cleanable
- Easy to handle
- With few moving mechanical parts, it requires minimal maintenance
- Can be integrated with all existing systems
- Small footprint
- Extremely modular, easily modifiable even at a later date
- Increases automation and productivity
- Gentle transport that does not damage or alter the pharmaceutical powder
- No product dispersion or contamination
- Increased hygiene and safety within departments
- Capable of transporting large quantities over long distances
