Wolf Group OÜ is a manufacturer of insulating polyurethane (PU) foams, joint sealants, adhesives and surface treatments. Founded in 1994 and headquartered in Tallinn, Estonia, the company has grown to become one of the leading producers in Europe. Wolf Group has production units in Estonia, Spain and France with additional sales branches in the United Kingdom, Germany, Portugal, Romania, Latvia, Lithuania and Ukraine. Wolf Group employs over 400 people globally. Wolf Groups products originate from the need and aim to enhance energy efficiency of buildings by significantly improving their thermal insulation properties – “We save energy”.
The production of PU foams uses various viscous chemicals, which when cold require more effort, time and energy to be mixed, pumped and dosed accurately. Increasing the temperature of the chemicals enables to decrease viscosity, but this heating process consumes a lot of energy.
As most factories in the world, the processes use compressed air provided by compressors. Most compressors are not very efficient, they convert only ca. 10-20 % into compressed air, while ca. 80-90% of the consumed energy is converted into heat. This is why many productions today use the waste heat already for heating the ambient air of production rooms and warehouses.
On the other side, investing in an industrial oven is costly (75.000€) and with 45kW nominal power also energy demanding. Combining the available waste heat and approach to heat the chemicals before processing seems to bear a lot of energy efficiency potential.
The Energy Scout Raimond Press came up with the idea to create a heat chamber right next to the compressor, directing the outcoming heat into the chamber. Compressors cooling system typically work with air or oil. The installed compressors use air cooling, so the heat energy can be easily directed into the custom designed chamber via a ventilation pipe. After the hot air heats the contents, the slightly cooled air will then be directed out the other side of the chamber and will still additionally be used to heat the warehouse.
Heat Recovery
- Industry sector: Chemicals for construction purposes
- Energy source: Electricity/Waste Heat
- Electricity savings potential: 212 MWh/year
- CO2 emissions savings potential: 132 tonnes CO2/year
- Potential cost reduction: 21,000 €
- Investment costs: 2,500 €
- Amortization Period: 43 days
- Company:
Wolf Group OÜ
Suur-Paala 10,
Tallinn, Estonia, 13619
http://www.wolf-group.com
A simple prototype was created to test the efficiency and prevent overheating by wrapping a storage shelf with plastic film. The tests were successful and no overheating occurred. The prototype has found temporary use in many ways as there is an oven constantly available that uses no additional energy.
To implement the idea, Energy Scout Raimond Press modelled a 3D drawing of the chamber. The design directs the air from the compressors output through the whole chamber. The design has a partition wall to maximise the heat exchange surface, directing the heat flow to the bottom and up again, before leaving and heating the warehouse. Currently the chamber is being constructed from Laminated veneer lumber beams and plywood on a larger scale. The chamber will be holding a storage shelf, which can accommodate four so called „Intermediate Bulk Containers“ (IBCs), each holding 1000 liter of chemicals.
The solution could be possibly adapted in many other ways in different manufacturing units depending on the specific needs of the production, as long as there is a need for heating of some sort and there is residual heat energy available. The output air is about 50°C, which limits the possible uses of such a system. Also, as compressors generate heat only when working, there must be use of compressed air for manufacturing to obtain residual heat energy. Since a longer warm-up time is expected, compared to an electric oven, planning ahead is necessary.
Participating in the Young Energy Europe trainings, the project generated many ideas worth researching, but no other approach had such a short amortisation time. In only 43 days the investment of 2,500 € is paid back by energy savings from not using an electric oven, amounting to 21,000 € per year. The Estonian jury awarded this project first place in the 2024 contest.
