Making heat eco-effective in Stockstadt Mill, Germany

For 10 years the wastewater had been running hot from the bleachery at our Stockstadt Pulp Mill in Bavaria, Germany. Where others just saw heat, however, Kai von Groddeck saw opportunity. As a mechanical engineer, he knew he could transform this wasted heat into a new energy source for the mill. 

The power of a heat exchanger 

Kai learned that the water pressed out of pulp during production was yielding an average temperature of 58°C / 140°F before entering the wastewater system for treatment. The water contained fibres and other wood residues that made harnessing its potential difficult. How could Sappi make the water system more eco-effective?  

“With a spiral plate heat exchanger,” Kai explained. “I discovered that the technology could transform the heat from the water into energy to save the plant an incredible 70,000 tons of steam each year!” This equals the energy needed to heat 1.900 households for one year. 

Even more, the process could reduce the water temperature by almost 15°C / 59 °F before entering the wastewater treatment system. This would further reduce the amount of excess heat entering the river Main. 

A one Sappi team 

While spiral plate heat exchangers are not new technology, it was certainly a novel device for Stockstadt given this particular wastewater challenge. And with this novelty came a bold approach to implementation.  

Kai went far beyond the confines of the paper production department. With a One Sappi approach, he assembled a team with a variety of experts from across the mill. Together, they installed and tested the heat exchanger to deliver on its energy-saving potential for Stockstadt. 

Today, the exchanger is meeting its targets by turning excess heat into a new energy resource for the mill. Along the way, Stockstadt has reached a new milestone on its journey to become more eco-effective.  

Eco-effective in action 

As for Kai, he’s still on the eco-effective mission, searching for more heat streams to reuse and waste to turn into resource. Except now, he has a team of supporters up and down the mill with a big win at their back. 

“Anytime anyone discovers a hot water stream, we’re now all thinking about the recovery opportunities”, explains Kai. “And how we can work together as one Sappi to deliver on the energy-saving potential.”