Design of a Microdistillation Column

By: Matti Manninen, Aarne Sundberg, Heidi Piili, Antti Salminen

Lappeenranta University of Technology, Laser Processing Research Group, Finland
Aalto University, Department of Biotechnology and Chemical Technology, Finland
Machine Technology Centre Turku Ltd, Finland

Distillation is the predominantly used separation method in chemical engineering. The device presented in this paper is called a microdistillation column, because the distilled volumes are measured in milliliters and dimensions in millimeters or less. There are two main reasons for a small distillation unit; firstly, it could theoretically be used in production, maybe in parallel with many such units. It could be used for example for hazardous or expensive materials, or in any case for applications which do not require large volumes to be distilled. More importantly, however, it could be used to study the distillation process in very small scale for the industrial scale device. Process development could then move from laboratory scale straight to industrial scale without need for expensive pilot plants.

This study focuses on the design and manufacturing process of such a microdistillation column, see figure 1. It is one of the smallest continuous distillation columns in the world at the moment. As such, the small size of the device posed several challenges in manufacturing. This case serves as a single and relatively simple example on how to design for advanced manufacturing methods; in this case laser processing. Another purpose of this paper is to give a clearer view of the advantages as well as disadvantages and limits of laser processing in small scale manufacturing.


Fig 1. Finished, 330 mm long microdistillation column.


The real benefits of use of laser welding and other laser manufacturing methods are typically based on new opportunities for product price, quality, throughput and design. Despite high investment typically defined to be major drawback of laser welding, the advantages gained through use of it can usually in practice, when the whole cost of production is evaluated, ensure such a remarkable improvement that the use of laser welding can be justified. Typically, the new generation lasers will make these advantages even more clear since the efficiency of the process is increased and thermal load decreased. The product discussed in this study is designed to utilize the strengths and advantages of laser processing when applicable, i.e. the main idea is not to always use laser processing, but select the process case by case. Similar approach has been used in various cases with good results, because no matter how much you favor any single manufacturing method, they all have their advantages and disadvantages. For example, trying to justify laser processing just because it is fascinating technology and not because it offers real benefits defeats its purpose, which is to offer wider variety of solutions to any design problems.