Industrial plants often have to deal with two different environmental issues at the same time. On the one hand, they have to tackle dust; on the other, volatile organic compounds (VOCs). Although on paper these two issues are lumped together under the heading of ‘air protection’, in reality they require completely different engineering approaches.
Dust consists of tiny particles. It is produced during cutting, grinding, the handling of aggregates, or welding. VOCs, on the other hand, are invisible gases. They evaporate from solvents, paints, adhesives and during drying processes. Our experience shows one thing: the most costly investment mistake is attempting to tackle both these problems with a single, universal device at the far end of the hall.
Understanding the enemy: What is the difference between dust and vapour?
The design of a dust extraction system always begins with an understanding of the physics of the problem. In the case of dust, the challenges include the weight of the particles, their abrasiveness, moisture content, and, not infrequently, a high risk of explosion (ATEX). A system is designed quite differently for heavy dust from a steelworks than for light, sticky dust from animal feed production.
VOCs behave differently. They are gases that mix instantly with the air in the hall. You cannot simply ‘sweep’ them into a pipe. The contaminated air stream must be precisely captured before it has a chance to escape from under the machine. Only after the gas has been contained within the ventilation duct is the appropriate chemical or thermal technology selected to neutralise it.
Tackling the problem at source rather than cleaning up the mess
A modern approach to environmental protection is based on one key principle: pollution isn’t tackled at the chimney top. It’s tackled right where it’s produced.
If a facility generates tonnes of dust, the first step is not to buy a powerful dust collector. We start by sealing transfer points, building enclosures around noisy machinery, and installing effective extraction hoods directly above saws or grinders. The situation is similar with VOCs. The best results are achieved by enclosing painting stations, switching to water-based paints, or lowering the process temperature to simply reduce solvent evaporation.
Attempting to extract dust and fumes scattered throughout the hall using general roof ventilation is a losing battle from the outset. It requires the movement of enormous volumes of air, which generates huge energy costs, whilst the effectiveness of such a solution remains negligible anyway.
Mistakes that cost millions
Why might two plants with identical production profiles have completely different emission levels? The problem rarely lies in the quality of the filters themselves. More often than not, it is a flawed system design that is at fault.
The most common mistake is to ignore fluctuations in production. Output at a factory is almost never constant. It depends on the time of day, the type of workpiece currently being processed, or the operator’s pace. Systems designed solely for ‘average’ loads quickly become overwhelmed during production peaks.
The second pitfall is a lack of technical expertise. Even the most expensive and best-designed extraction system will lose its effectiveness if the maintenance staff do not regularly clean the ductwork, replace the filter bags and check the tension of the fan belts. A dust extraction system is not a ‘fit and forget’ type of device.
Summary
Effectively reducing dust and VOC emissions is a process that requires a precise diagnosis, not simply the quick installation of a standard filter. Success depends on physically capturing pollutants at the point of generation and selecting the appropriate technology for the nature of the substances being released. Only a combination of a leak-tight process, well-designed local ventilation and regular maintenance ensures that the plant will meet stringent environmental standards, without wasting the budget on oversized fans.
