First, extensive research has been carried out to find an industrial partner willing to take part in the project and with a tunnel furnace adapted for waste heat recovery. Eco-Tech Ceram identified the Valence d'Agen factory of Villeroy & Boch (in France) to be suitable for the project. This is a ceramic factory using a 150-m long tunnel furnace.
The detailed information of the tunnel furnace was collected through on-site measurement campaigns and a technical audit carried out independently by a specialized partner of Eco-Tech Ceram. This work was difficult and slowed down by the sanitary and legislative constraints due to the COVID crisis (reduction of the tunnel furnace activity, travel restrictions...).
Eco-Tech Ceram used the collected information to investigate the best configuration for recovering the waste heat of the tunnel furnace with the Eco-Stock solution. 24 scenarios were studied to define the best technical parameters of the solution (size and number of storage units, durations of charge/discharge, heat storage material, power of the equipment...). The location of the Eco-Stock solution in the factory was defined in agreement with Villeroy & Boch. This is a critical point for the industrial partner since the implementation of the Eco-Stock solution reduces the available space in the factory. 3D diagrams have been made to size the installation and calculate the length of pipes.
The equipment to be implemented have been identified and the cost of the designed solution have been estimated.
Tunnel kilns characteristics are different from those of continuous kilns: the fumes temperature level is lower. ECO-TECH CERAM has chosen to add a POWER TO HEAT system to raise the temperature of the fumes by converting electricity into heat, and decarbonate a part of the heat used.
This storage system optimises the purchase cost of electricity, the price of which fluctuates sharply during the day.
The heat is therefore drawn from the kiln at 400°C, reheated with a PTH at 600 degrees and then re-injected directly both into the kiln and into the storage simultaneously. The storage enables the price of electricity to be smoothed out and, with POWER TO HEAT, ensures that the air is sufficiently hot.
In conclusion, the H2020 project has made it possible to:
- Demonstrate the technical feasibility of recovering this heat by controlling the pressure conditions in the kiln, the ability to increase this heat with the PTH to 600 degrees, and the ability to reinject the decarbonised hot air into the kiln in a controlled manner to reduce natural gas consumption, with or without storage.
- Validate the quality of the air returned to the kiln, which must be very clean in accordance with the high industrial partner's requirements.
- Validate the economic relevance of this solution, with a production capacity of 1.5 GWh/y at an average price €5 lower than that of gas.
- Validate a technological solution that reduces CO2 emissions by a factor 3 compared with fossil fuels.
Lastly, ECO-TECH CERAM wants to develop its business in a future market, namely that of massive electricity storage. This is a market that is essential to the development of rapidly growing renewable energies (climate change mitigation) and to the adaptation of networks that will need to be coupled and reinforced with solutions such as POWER TO HEAR TO POWER, which could be the subject of a future European project (Innovation Fund).
