Retrofit with a sense of proportion

Retrofit with a sense of proportion

When the industry talks about sustainability, the focus is often on new technologies or entirely new plants. Yet there is often enormous potential to be found in existing infrastructure. This is precisely where retrofit comes in: existing plants are modernised, technically optimised and made more energy-efficient – in a way that conserves resources and is usually significantly cheaper than purchasing new equipment. For Venjakob Maschinenbau in Rheda-Wiedenbrück, this is business as usual.

The topic is becoming increasingly important, particularly in industrial finishing technology. Paint and coating systems are among the most energy-intensive processes in industry. Dry coating technology, air handling and exhaust air purification, in particular, result in high energy consumption. Large volumes of air must be heated, circulated, filtered and discharged. At the same time, energy costs and regulatory requirements are on the rise.

“The issues and reasons that bring customers to us vary,” reports Sören Steegmann, Head of Service and Sales at Venjakob Maschinenbau. “These range from technical adjustments to make production more cost-effective to modernisation or retrofitting measures aimed at saving energy.”

The advantage over a new installation is that production downtime usually remains manageable and the investment costs are significantly lower. “Whether I invest between 100,000 and 600,000 euros or two million for a brand-new plant – that’s a huge difference,” says Steegmann. Retrofit projects often pay for themselves within three to five years.

Heat recovery saves energy

A recent example is the retrofitting of heat exchangers on an existing drying line. The customer’s aim was to reduce energy costs and meet sustainability targets.
The challenge: In drying processes, warm exhaust air is continuously extracted, whilst at the same time cold fresh air from outside has to be reheated. This results in significant energy losses, particularly in winter.

The solution was to utilise the existing exhaust air to generate energy. Heat exchangers installed on the roof return part of the thermal energy back into the process. Venjakob fully integrated the technology into the existing plant control system, including sensors, visualisation and process monitoring.

“This means you no longer have to heat the air from 20 to 60 degrees, but instead get pre-heated air back,” explains Steegmann. Initial analyses indicate potential savings of around 30 per cent. Notably, production was able to continue throughout the retrofit, with only a few hours’ interruption.

Retrofitting UV technology

At Venjakob, however, retrofit means not only energy savings but also adaptation to new production requirements.
For example, an existing system at one customer’s site was upgraded with a UV curing module to enable the use of UV coatings in future. In another project, UV technology was already in place, but it was operated by a robot that was reaching its limits in terms of throughput. The result: reduced production speeds and quality issues.

The solution was a standardised UV module that was integrated directly into the existing drying system. “This involved about a week’s downtime. We then monitored production alongside the customer to ensure the quality was right afterwards,” reports Steegmann.

Less overspray, lower consumption

There is also considerable potential for optimisation in spray application technology. With the ‘Kante Plus’ system, Venjakob has developed a retrofit solution for improved finishing results in the timber and furniture industries.

Additional spray guns, more precise sensor technology and expanded software parameters enable precise control right up to the edge of the workpiece. This reduces overspray – that is, the coat that was previously sprayed beyond the edge.

This saves material, reduces cleaning effort and improves process stability.

Small changes with a big impact

Not every retrofit project is so clearly visible. Often, benefits can be achieved simply through targeted optimisations of small details.

For example, Venjakob replaces friction wheels – which are prone to wear – in older high-temperature dryers with more durable claw couplings that have only recently been developed. This improves process stability and reduces maintenance requirements.

Another example is the retrofitting of flow meters directly onto individual paint spray guns. Blockages or variations in material are detected at an early stage, before rejects are produced or production batches need to be reworked.

Where retrofit reaches its limits

Despite all its advantages, retrofit is not always the best solution. Limitations arise particularly when production concepts undergo fundamental changes or significantly higher output is required, which cannot be achieved with much older coating lines.

“If the conveyor is designed for a specific speed, there’s only so much you can achieve,” explains Steegmann. A retrofit can quickly become complex, particularly with older systems.

For Venjakob, therefore, retrofit is not an end in itself, but a strategic middle ground between continued operation and new investment – modernising where it makes sense, and rethinking where it becomes necessary.