Heat recovery in a production process

The belt dryer of OSB wood chips has been retrofitted in a plant which manufactures wood-based products. A low-temperature pre-drying machine has been implemented. Waste heat recovered from a production process has been used to cover energy needs of the new unit.

The waste heat energy is used in the belt pre-drying machine. It is generated while producing formalin. This process requires the technological line to be cooled at many stages of the process. In order to maintain a stable process flow, it is necessary to decrease the formalin temperature from 70°C to approx. 50°C.

The technological line and formalin are cooled in the plate heat exchangers. Previously, the heat was irreversibly lost to the atmosphere through the open cooling towers.

Currently, it is directed first to the newly-built drying unit where it is cooled when input material is pre-dried. Finally, it is led towards the cooling towers. 

Since the waste heat has been applied in the production process, natural gas consumption has been substantially decreased. This energy source is used for the drying process in the currently operating installation. 

Thanks to the retrofit the consumption of final energy has been reduced by more than 106,000 MWh which provides for EUR 2.2 million. With investment outlays of EUR 8.7 million, the simple payback period comes to 4 years. The investment is accountable for the CO2 emission reduced by approx. 40 tones.