Voith recovers waste heat at Koehler Paper mill

Voith’s SteamBooster technology is helping Koehler Paper reduce natural gas consumption and carbon emissions at its Kehl mill in Germany by converting high-temperature exhaust heat from a coating machine back into usable process steam.

The system forms part of a three-stage heat recovery concept installed on the mill’s SM 8 offline coating machine and has been operating since June 2025.

Exhaust temperatures reach up to 300°C

The coating process uses Voith non-contact MCB dryers and generates exhaust air at temperatures of up to 300°C. Previously, a significant proportion of this thermal energy left the production process without being reused.

The SteamBooster captures this energy through a heat exchanger and transfers it to condensate, producing steam that can be returned directly to other mill processes.

System generates around one tonne of steam per hour

At the Kehl installation, the technology produces approximately one tonne of usable steam every hour.

Returning this energy to the production system reduces the load on the mill’s conventional boilers, helping lower natural gas consumption and the associated operating costs.

Carbon savings reach 1,500 tonnes annually

Voith says the complete three-stage heat recovery configuration can avoid up to 1,500 tonnes of CO₂ emissions per year.

The result demonstrates how energy recovery technologies can contribute to decarbonisation even when mills continue to operate energy-intensive drying and coating processes.

Technology expands beyond tissue applications

SteamBooster was originally developed and patented for recovering thermal energy from tissue machine hoods, but Voith has since adapted the concept for broader paper production applications.

The company says the technology can generally be used on paper machines where exhaust air temperatures exceed approximately 100°C, including hot-air dryers and vacuum blower systems.

Retrofit design supports existing mills

The system can be installed during regular maintenance shutdowns, allowing existing paper mills to incorporate heat recovery without requiring complete production-line replacement.

It can also be integrated into new machines, giving producers the option to include waste-heat recovery from the initial design stage.

Typical mills could recover up to five tonnes of steam

Depending on machine configuration and available exhaust heat, Voith estimates that an average paper mill could recover between one and five tonnes of steam per hour using the technology.

The company also states that typical installations can achieve a payback period of less than two years, making heat recovery potentially attractive from both environmental and financial perspectives.

Energy efficiency becomes critical for paper packaging

Paper and board production remains highly energy-intensive, particularly during drying, coating and finishing. This means improvements in thermal efficiency can have a significant impact on the carbon footprint of fibre-based packaging materials.

As packaging producers and brand owners increasingly examine Scope 3 emissions, energy consumed during paperboard manufacturing is becoming an important part of wider packaging decarbonisation strategies.

Waste heat becomes a production resource

The Koehler Paper installation demonstrates how energy that would traditionally be released into the environment can instead become part of a closed industrial energy loop.

By recovering high-temperature exhaust heat and converting it into process steam, technologies such as SteamBooster can help paper producers reduce fuel demand while improving the efficiency of existing production assets.