A leaky or badly insulated vapor hood in the dryer section prevents the hood air system from operating with a high waste air dewpoint, so that it is not energy efficient. The result: higher power and steam consumption in the air systems and lower output of the heat recovery unit. The hall climate is also impaired by hood leaks. By optimizing or renewing the extractor hood the exhaust air dewpoint can be increased and power and steam saved. 

Frequently the air system in the dryer section is operated with constant air input and extraction, regardless of the type of production run that has just taken place. In the case of paper grades with low water evaporation the system is then operated inefficiently in energy terms with too low a dewpoint. The air flow and thus the power and steam requirement of the hood air system is then unnecessarily high and the output of any heat recovery systems is reduced. A Voith dewpoint control system can eliminate these energy drawbacks and the system can adapt ideally to grade changes. 

In the case of a one-stage heat recovery system for machine supply air heating generally only around 5-8% of the energy content of the hood exhaust air of the dryer section is used. The rest just disappears through the roof. Voith retrofittable multi-stage heat recovery systems allow the energy from the hood exhaust air, but also that of other waste heat flows e.g. vacuum pump waste air, to be used efficiently. As well as the machine supply air the water for the process (fresh water, spray water, white water) and/or for heating the machine hall ventilation can therefore also be heated. 

Combining the air system and steam/condensate system of the dryer section of the paper machine is absolutely essential to run the paper machine in an energy-efficient way.

Vapors and condensate from the dryer section can be used to reduce the steam requirement in the hood supply air system. Using this energy to heat the process water is often not energy efficient, because this can be done using alternative means.

Depending on your system we develop intelligent solutions that allow good energy savings in existing facilities in particular. 

In the case of machine hall ventilation systems with hot water supply and integrated heat recovery units Voith EOS™ allows further reduction of the power and steam requirement. It can be used in new systems and is particularly suited to existing facilities.

Depending on the system the ROI can be less than one year.

An energy audit of the air system and/or steam and condensate system can identify potential savings in the process air system, heating system for dryer section, hall ventilation and air cooling and air conditioning systems. It also allows for overarching considerations, e.g. integrating the process water system of the paper machine. The results often indicate potentials previously unidentified by the operator. Specific optimization and rebuild solutions can be derived as a result.