Waste heat from baking ovens keeps buffer tank temperature stable

The cleaning cycle at this industrial bakery was being disrupted by an undersized buffer tank. A larger stratified buffer tank, combined with waste heat from the baking ovens, now provides the stability the process needs. Hot water is always available without driving up energy consumption.

The first challenge? Not enough high-pressure hot water. On top of that, the hot water had to be available at all times so the machines could be cleaned on schedule. 

The small buffer tank soon turned out to be the culprit. It lacked the capacity to absorb peak demand and was regularly drained. Refilling it with hot water every time took far more energy than necessary. 

The second challenge was the layout. The buffer system stood in the middle of the production hall, where it got in the way of daily operations. So we moved the entire system to an outdoor unit. 

Stratified buffer tank makes the most of available energy 

Callens engineered and installed an 80 m³ stratified buffer tank. Cold water, at approximately 15 °C, enters at the bottom. The condensers heat the water to 65 °C, after which it is fed back into the top of the buffer tank.

With this design it is possible to store energy efficiently and make it available at the right time, even when demand varies significantly. 

Waste heat from condensers supplies the buffer tank  

Two condensers on the production lines recover heat from the airflows. This heat is used to warm the water, which is then injected into the top of the buffer tank.  

A major advantage: the condensers can run continuously, regardless of the immediate heat demand. That way, the system recovers as much energy as possible, even when production fluctuates.

Compact outdoor container unit

To free up space in the production hall, we moved the entire system into an outdoor container, which we built from scratch. It houses all the technical components:  

• pumps for water supply and circulation
• treatment units for the cleaning water
• hydraulic connections to the buffer tank
• central heating boiler with heat exchanger

Technical refinements make the difference

Maintaining stratification in the buffer tank was a challenge in its own right. That’s why we fitted the tank with four suction lances to draw off water. If the water level drops, there’s always another suction lance that can reach the hot top layer.

This solution is particularly suitable for production environments where:

• large volumes of hot water are required for cleaning or process applications
• waste heat is available from ovens, airflows, or other systems
• heat demand fluctuates significantly over time
• optimizing space in the production environment is important