How to Scale Up a Drying Process from Laboratory to Industrial Production

Scaling up a drying process from laboratory testing to industrial application is far from being an easy task as it implies more than just enlarging the batch volume. While the process can work perfectly for a small quantity of materials, its performance may vary significantly in case of hundreds of kilograms or even several tonnes of raw materials to be dried. Heat transfer, airflow, humidity transfer, residence time, and material handling all influence the quality of the end product directly.

For an industry, scale-up is about reaching the necessary production level and maintaining quality standards and efficiency.

Reasons Why the Lab Result May Not Be Useful in the Real Process

Drying tests in the lab are usually carried out in controlled conditions. Temperature, air flow, humidity, feed size, and time required for drying can all be controlled. The size of the feed material is quite small, which means that heat may easily reach the product and the moisture may easily evaporate.

In contrast, in an industrial process, things are quite different. First of all, several hundred kilograms of material are placed in the dryer, and as a result, the heat and air distribution may not be uniform throughout the feed material. As a consequence, the inner portion of the material would take more time to release its moisture to the surface.

Furthermore, some products may develop cracks, shrink, lumps, sticking or even change their properties completely. In an industrial process, such situations will occur quite often, while in a lab they will not happen at all

What Should Be Taken Into Account During the Scale-Up Process?

First of all, one should take into account heat transfer and air flow. There are different relationships between the volume, surface area, air flow rate, and heat load of the product in the industrial dryer. Engineers have to calculate how much heat will be necessary and how effective heat transfer will be.

The second factor to pay attention to is the airflow. The lack of airflow can increase the drying time and result in non-uniform distribution of moisture; the excess of airflow can increase the energy expenses or even affect sensitive materials. Thus, the air flow distribution should be calculated based on the properties of the product.

The third factor is moisture movement. The drying rate changes during the process; the surface moisture can be dried quickly at the initial stage, but the internal moisture may become difficult to remove later. This knowledge allows choosing the proper temperature, residence time, and other factors of the process.

The last factor is the material behavior. Different materials may shrink, deform, agglomerate, and stick under the influence of industrial drying process.

Choosing the Appropriate Industrial Dryer

Selection of an appropriate dryer is one of the key considerations while scaling up. The selection will depend on various technologies which have their applications based on different types of materials and production processes.

For example, a tray dryer would be more appropriate for batch drying while a fluid bed dryer would be useful to obtain good heat and mass transfer for the appropriate particulate materials. In contrast, a spray dryer is generally employed to form dry powder from liquids or slurries, while a rotary dryer could be chosen to process bulk solids continuously.

There are many other technologies that could be considered depending on the type of material and process.

Other factors like production rate, feed type, final moisture content, sensitivity to heat, residence time, energy use, and cleaning must also be considered.

Process Monitoring and Energy Efficiency

Parameters such as inlet and outlet temperatures, airflow, humidity, feed rate, residence time, and final moisture content must be carefully monitored during scale-up. The comparison of these parameters with laboratory and pilot scale data allows engineers to find process variations and optimize operation.

Efficiency in energy use is also one of the key issues for industrial scale. Good insulation, effective airflow, efficient heaters, heat recovery, and proper temperature control can help reduce energy losses and reduce costs.

Why Expert Help Is Important

Collaboration with an industrial dryer manufacturer allows to close the gap between lab data and real industrial production. Manufacturers such as Kerone have a lot of experience in providing solutions for industrial heating and drying processes in various sectors, including pharmaceuticals, food industry, chemicals, and agriculture.

Systematic approach to the problem that includes laboratory evaluation, pilot test, process optimization, equipment selection, and industrial validation allows to minimize production risks.

Scale-up not only increases production capacity but also maintains high product quality, minimizes waste, controls energy usage, and ensures reliable industrial production process.

The author writes about industrial drying, heating, and thermal processing, sharing simple and practical insights on industrial processes and technologies.