Removing VOCs in the manufacturing of paints and coatings

Solvent-based paints and coatings are valued in numerous industries due to their resilience, smoothness and visual appeal. On application, however, they emit Volatile Organic Compounds (VOCs) that can harm the environment and are therefore subject to strict regulation. In some cases, manufacturers can address the issue by switching to water-based alternatives instead of solvent-based products. Where that is not possible, they must reduce VOC emissions. DESOTEC’s range of activated carbon filters can offer an effective, cost-efficient and flexible way to remove VOCs in many production and application processes.

The problem

The range of applications for solvent-based paints and coatings is broad, presenting a huge challenge to countless sectors.

Due to their ability to withstand the elements and saltwater, solvent-based products are widely used to prevent the corrosion of parts for everything from aeroplanes, boats and vehicles to offshore wind turbines.

They can also create smooth surfaces: for example, to reduce friction in pipes carrying oil or water.

Some musical instruments, such as high-end pianos, may be given a solvent-based coat to protect the material and give it a high-shine appearance.

In pharma, tablets may be coated to control the release of the drug or mask its taste and smell. Pain relief patches may use solvents to bind the active ingredients to the plaster.

Solvent-based coatings even play a role in the beauty industry, where they give cosmetic and perfume bottles a shiny, attractive appearance.

All sectors are subject to legislation limiting VOC emissions. Limits vary between industries and regions but are generally set at around 50 mg/m3.

Naturally, it makes sense to tackle the problem at source where possible. If limits are exceeded only slightly, businesses can try reducing the amounts of paints they use or adjusting ventilation systems.

If concentrations are still too high, they can try switching to High Solid Paints. These have a lower VOC content and therefore the risk of exceeding the limit is reduced.

However, for many applications, solvent-based products remain the best or only option.

The solution

Several technologies are used to reduce VOC emissions, with thermal oxidation being the default choice for many producers. This involves burning emissions to turn the VOCs into carbon dioxide or water, which can then be released harmlessly into the atmosphere.

However, this can be expensive and inefficient if production is discontinuous, as energy is required to burn emissions even when VOC concentrations are low or non-existent.

DESOTECs’s mobile filtration system can be a more cost-effective solution as emissions simply pass through the filters, with the activated carbon adsorbing pollutants if they are present.

Therefore, activated carbon filters are particularly suited to scenarios where production is discontinuous, or where there are high flow rates with low concentrations of VOCs.

DESOTEC's qualified engineers can give potential clients an honest appraisal of the suitability of activated carbon in particular scenarios. If they believe thermal or other technologies would work better, they will say so.

The results

If mobile activated carbon filters are a viable option, DESOTEC engineers will be able to advise on the model needed. With correct installation, it will reduce VOC concentrations to below legal limits.

There are several other benefits to the DESOTEC mobile filtration system:

Unlike thermal oxidation or bio-filters, DESOTEC filters are a flexible plug-and-play system. As DESOTEC rents out its units, clients do not need to make a major upfront investment: if their production rate drops, they can get the filter removed. If their production rate increases, DESOTEC’s modular system makes it straightforward to exchange the filter for a larger one or install extra units in series or in parallel.

Even when thermal or bio-filter solutions are fitted as the primary method for removing VOCs, DESOTEC filters can be a back-up.

DESOTEC filters are also very user friendly. Flame-ionisation detectors (FID) monitor VOC concentrations so it is clear when the filter needs to be exchanged. DESOTEC personnel will then organize transport of the spent carbon filter to a DESOTEC facility for reactivation or disposal.