Scientists Have Created a Technology for Non-Contact Cleaning of Industrial Equipment

13:16, November 26, 2021

It allows you to remove dirt more accurately, safely and cost-effectively

Scientists from the University of Helsinki and Ural Federal University together with the Finnish company Altum Technologies Oy have developed a technology for contactless cleaning of complex industrial equipment (pipelines, heat exchangers, technical tanks). An article about the new technology was published in the journal Ultrasonics Sonochemistry.

Normally, to clean hard-to-reach areas of industrial equipment, you either have to stop all production, or send high-power ultrasonic waves simultaneously in different directions, "at random".

In other cases it is necessary to install a big number of powerful transducers or to use toxic chemicals, destroying the environment.

A new method of cleaning equipment using ultrasonic waves allows to focus the signal and thus optimize the cleaning. Accordingly, the equipment is cleaned better: as accurately, precisely, qualitatively, environmentally friendly, less energy-consuming and, consequently, more economical.

The new method has been tested experimentally. Scientists subjected to the influence of ultrasonic waves transparent tubes with calcium paste on their surface, which simulated industrial pollution. First, the tubes were cleaned with the standard method, and then the time reversal method, the so-called method of Mathias Fink. The experiments lasted the same amount of time with the same power consumption. In the second case, the researchers had enough four sensors to focus an ultrasonic wave of power on the tubes, which was enough for fast and thorough cleaning - "without unnecessary noise and dust," as the developers put it. The volume of removed contaminants was three times greater than in the first, "standard" approach.

Creating the new technology, the scientists used the method of signal processing with time reversal, developed by the French physicist Matthias Fink in the early 1990s. This method is widely used in medicine (visualization of internal organs, treatment of kidney stone disease, hyperthermia of the brain), in non-destructive control of technical objects and units, in particular, communication networks and power supply. Scientists of the University of Helsinki and UrFU were the first to apply Fink's method for ultrasonic cleaning of complex industrial objects and equipment from contaminants.

"Time reversal is a method of focusing wave energy at a selected point in space and time. Usually, when you need to direct an ultrasonic wave to a certain point in space, you must first find out the state of the medium in which it is located - the presence and configuration of inhomogeneities, obstacles. And describe them in wave equations. This is not an easy task, the solution of which, however, does not get rid of errors. Fink's method eliminates the need to study and characterize the environment, as well as to carry out cumbersome calculations," explains the essence of the method Maria Gricevich, research participant and co-author of the article, adjunct professor at the University of Helsinki, senior researcher at the UrFU.

First, in the computer model, a wave is fed from the point in the vessel that is planned to be affected by ultrasound. As the simulated wave propagates, it is recorded and measured by computer models of sensors "mounted" around the perimeter of the vessel. This gives a clear indication of what kind of wave needs to be generated in the experiment to travel through a given medium in the opposite direction.

"Then the real sensors feed ultrasonic waves of a given property to a selected area - the point from which the wave propagated in the model. According to the laws of physics, passing through the same medium in the opposite direction, the waves will be focused exactly at this, the previously intended point, regardless of the presence of inhomogeneities on their way," says Maria Gricevich.